Research ArticleFatty Amides from Crude Rice Bran Oil as GreenCorrosion Inhibitors

E Reyes-Dorantes12 J Zuntildeiga-Diacuteaz12 A Quinto-Hernandez1 J Porcayo-Calderon23

J G Gonzalez-Rodriguez3 and L Martinez-Gomez24

1Tecnologico Nacional de Mexico Instituto Tecnologico de Zacatepec Calzada Instituto Tecnologico 2762780 Zacatepec MOR Mexico2Instituto de Ciencias Fısicas Universidad Nacional Autonoma de Mexico Avenida Universidad sn62210 Cuernavaca MOR Mexico3CIICAp Universidad Autonoma del Estado de Morelos Avenida Universidad 1001 62209 Cuernavaca MOR Mexico4Corrosion y Proteccion (CyP) Buffon 46 11590 Mexico City Mexico

Correspondence should be addressed to J Porcayo-Calderon jporcayocgmailcom

Received 1 February 2017 Revised 27 March 2017 Accepted 5 April 2017 Published 18 May 2017

Academic Editor Hassan Arida

Copyright copy 2017 E Reyes-Dorantes et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

Due to its high oil content this research proposes the use of an agroindustrial byproduct (rice bran) as a sustainable option for thesynthesis of corrosion inhibitors From the crude rice bran oil the synthesis of fatty amide-type corrosion inhibitors was carried outThe corrosion inhibitory capacity of the fatty amides was evaluated on an API X-70 steel using electrochemical techniques such asreal-time corrosion monitoring and potentiodynamic polarization curves As a corrosive medium a CO

2-saturated solution (35NaCl) was used at three temperatures (30 50 and 70∘C) and different concentrations of inhibitor (0 5 10 25 50 and 100 ppm)Theresults demonstrate that the sustainable use of agroindustrial byproducts is a good alternative to the synthesis of environmentallyfriendly inhibitors with high corrosion inhibition efficiencies

1 Introduction

Corrosion is the degradation process of a material due toits exposure to the environment and is one of the majorproblems affecting its performance safety and integrityDespite the continuous advances in the field of materialswith corrosion resistance the use of corrosion inhibitors isone of the most practical and economical ways to control it[1 2] An inhibitor is defined as any chemical which whenadded in small concentrations to an aggressive environmentsignificantly reduces the corrosion rate of the material incontact with the corrosive environment A wide variety oforganic and inorganic compounds have been used to controlcorrosion It has been demonstrated that many organicmolecules can act as corrosion inhibitors because of theiraffinity with the metal surfaces replacing the adsorbed watermolecules and thereby forming amolecular film that prevents

the metal dissolution In the particular case of environ-ments where the presence of hydrocarbons predominates theinhibitors based on amide- or imidazolines-type compoundsare widely used [3ndash9] The excellent performance of this typeof corrosion inhibitors is associated with the fact that itsmolecules are constituted by two essential parts an electron-rich polar part capable of adhering onto a metal surfacethrough coordination bonds and a hydrophobic part whichcan effectively prevent the diffusion of contaminants presentin the aggressive environment [2 5 9ndash12] In addition tothe above it has also been reported that the presence ofunsaturation or other functional groups of the alkyl chainsalso influences their inhibition efficacy [7 9 13] Thesecharacteristics are provided by the nature of the vegetable oilused for the synthesis of this type of inhibitors

From the point of view of sustainable development itis imperative to search for new alternative nonconventional

HindawiJournal of ChemistryVolume 2017 Article ID 2871034 14 pageshttpsdoiorg10115520172871034

2 Journal of Chemistry

sources of vegetable oils These new sources of vegetable oilscan be used for applications as diverse as biofuels synthesisbiopolymers corrosion inhibitors and so forth [6 9 14 15]In this sense rice bran is a byproduct of the rice grain millingprocess In general the overall yield of the ricemilling processis about 60 white rice 10 broken grains 10 bran and20 husks [16] The rice bran is the main oil source ofthe rice grain in addition to a good content of proteinstocopherols and bioactive compounds Its oil content variesfrom 10 to 23 and its fatty acids are 47monounsaturated33 polyunsaturated and 20 saturated in addition to asignificant fraction of unsaponifiable components (43) [1718] However only 10 of the worldrsquos rice bran production isused for oil extraction and the remainder is used as a low-cost feed for cattle and poultry The high oil content of therice bran combined with the presence of the lipase enzymecauses that this byproduct has a short shelf life due to thedegradation of its oil [16ndash18]

Therefore the aim of this work is to explore the use of asustainable source for the synthesis of corrosion inhibitorswhere the source of vegetable oil is environmentally friendlyby not affecting the food chain does not replace cropsand does not use new crop fields for their production Theamide-type inhibitors synthesized were evaluated by twotypes of experimental measurements real-time corrosionmonitoring and potentiodynamic polarization curves Thecorrosivemediumusedwas aCO2-saturated sodiumchloridesolution at different temperatures

2 Experimental Procedure

21 Synthesis of Fatty Amides from Crude Rice Bran OilThe rice bran was obtained from a local mill (Puente deIxtla Morelos Mexico) Rice bran was collected a few hoursafter its production Crude rice bran oil (CRBO) contentwas determined by the Soxhlet method where the solventused was hexane The extraction of the CRBO used for thesynthesis process was carried out in a stirred batch system atroom temperature using a rice bran to solvent ratio of 1 10Chemical and physicochemical characterization of theCRBOwas made

The method used for the synthesis of the fatty amides is amodification to the procedure suggested by Kumar et al [19]In general the procedure consists of introducing one mole ofcrude oil with 3 moles of aminoethylethanolamine (AEEA)into the reactor (1 3 CRBO-AEEA ratio) The mixture isheated to 140∘C with stirring at atmospheric pressure Oncethe temperature is reached the course of the reaction ismonitored by thin-film chromatography (TLC) until thetriglycerides disappear completely

22 Electrochemical Evaluation of Fatty Amides as CorrosionInhibitors The evaluation of the electrochemical perfor-mance of the synthesized compounds was performed onan API X-70 steel commonly used in the manufactureof pipelines for the transportation of hydrocarbons Theperformance of the inhibitors was evaluated by two typesof electrochemical techniques namely real-time corrosionmeasurements and potentiodynamic polarization curves

Real-time corrosion measurements were performedusing an identical three-electrode probe Steel samples withdimensions of 03 lowast 10 lowast 10 cm were cut and a conductivewire was spot-welded on one of its narrow sides For theelectrochemical tests three steel samples were encapsulatedin acrylic resin with a separation between them of 1mmEach encapsulation was abraded with silicon carbide abrasivepaper from 120 to 600 grids then the encapsulations werewashed with alcohol and distilled water dried and imme-diately employed in the electrochemical tests A solutionof NaCl (35 by weight) saturated with CO2 was usedas the corrosive medium The solution was saturated withCO2 two hours prior to the tests and the CO2 bubblingwas maintained during the corrosion tests Corrosion testswere for 24 hours at a test temperature of 30 50 and70∘C with light stirring Encapsulations were kept insidethe electrolyte for one hour before any inhibitor was addedThe concentrations of inhibitor evaluated were 0 5 10 2550 and 100 ppm For each electrochemical test a volumeof 400mL of electrolyte was used The multitechnique elec-trochemical monitoring equipment (SmartCET) is basedon a combination of electrochemical techniques such aselectrochemical noise (EN) linear polarization resistance(LPR) and harmonic distortion analysis (HDA) and as aresult of this interrelationship both the corrosion rate andthe pitting corrosion behavior of the material under studyare obtained The measurement cycle is carried out for aperiod of 430 seconds as follows measurements of EN incurrent and potential second to second for 300 secondsLPRHDA measurements for 100 seconds and electrolyteresistance measurement for 30 seconds The details of thisreal-timemonitoring technique are described in the scientificliterature [20 21]

For potentiodynamic polarization curves a typical three-electrode arrangement was used where the reference elec-trode was a Pt wire and as counterelectrode a high-puritygraphite rod was used From this type of tests it is possible todetermine the electrochemical parameters such as corrosionpotential and corrosion rate in addition to the anodic andcathodic slopes from the extrapolation of the Tafel slopesof the obtained curves In this case steel samples with areaction area of 1 cm2 were encapsulated in acrylic resinEncapsulations were abraded with silicon carbide abrasivepaper from 120 to 600 grids after that they were washedwith alcohol and distilled water dried and immediatelyemployed in the electrochemical test Corrosive conditionswere the same as those of real-time corrosion measurementsIn order to ensure that the inhibitor achieved the maximumsurface coverage of the working electrode before starting theassay samples were allowed to stabilize for 24 hours intoelectrolyte prior to performing the assay Potentiodynamicpolarization tests were performed from minus400mV to 600mVwith respect to open circuit potential (119864corr) at a sweep rateof 1mVs Electrochemical parameters were calculated usingthe extrapolation Tafel method considering an extrapolationpotential of plusmn250mV around the value of the corrosionpotential Potentiodynamic polarization curves were carriedout using an ACM Instruments zero-resistance ammeter(ZRA) coupled to a personal computer

Journal of Chemistry 3

100

90

80

70

60

4000 3500 3000 2500 2000 1500 1000 500

Wavenumber (cmminus1)

Tran

smitt

ance

()

2851

69

3254

13

3079

52

3008

36

1740

78

1649

32

1624

07

1558

89

1461

19

1375

92

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72

1270

11

1233

46

1054

49

1121

46

1171

16

921

6184

162 773

8371

876

555

28

2921

12

(a)

3298

66

3009

10

2851

95

2921

17

1640

30 1557

64 1462

75

1374

83 13

056

912

072

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547

211

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010

617

9

883

22

718

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921

8495

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834

500

5541

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1265

02

3272

90

100

90

80

70

60

4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

Wavenumber (cmminus1)

(b)

Figure 1 FT-IR spectra of the synthesis of the fatty amides from CRBO and AEEA (a) initial mixture (119905 = 0 minutes reaction) and (b) finalmixture (80 minutes reaction)

3 Results and Discussion

31 Synthesis of Fatty Amides Rice bran analysis indicated acrude oil content of 21 (dry basis) which is in agreementwith data reported in the literature [16ndash18] Its molecularweight calculated from its saponification index was 92336and its chemical characterization showed an oleic acid con-tent of 4848 3526 of linoleic acid and 1454 of palmiticacid similar values to those reported in the literature forthis type of oil [16 17] Knowledge of the type of fatty acidspresent in the oil is important given that both the lengthand unsaturation of the hydrocarbon chain contribute to themode of adsorption and inhibition efficiency of the inhibitormolecule [7]

Figure 1 shows the FT-IR spectra of the fatty amidessynthesized from CRBO and AEEA From Figure 1 it can beseen that the signal at 1740 cmminus1 corresponding to the C=Ostretching of the triglycerides disappears and a new signalis observed at 1640 cmminus1 It is known that the presence of

this signal is characteristic of the peaks corresponding to theamidation product (fatty amides) [10ndash19] Evolution of theFT-IR spectra at different times (spectra not shown) indicatedthat after 80minutes of reaction the complete disappearanceof the triglycerides was achieved suggesting formation offatty amides

32 Real-Time Corrosion Measurements of Synthesized FattyAmides Figure 2 shows the effect of the inhibitor addition(fatty amide) on the corrosion rate (based on RPL mea-surements) of API X-70 steel immersed in CO2-saturatedsaline solution at different test temperatures In all cases theinhibitor was added 60 minutes after the measurements werestarted RPL measurement involves measuring the polariza-tion resistance (Rp) using a sinusoidal polarization of smallamplitude (plusmn20mV) of the working electrode (steel understudy) In this case the slope of the potential-current sweep isRp which is inversely proportional to the corrosion currentdensity and it is subsequently transformed to corrosion rate

4 Journal of Chemistry

Addition of inhibitor

1

10

100

Cor

rosio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(a)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Cor

rosio

n ra

te (m

py)

(b)

1

10

100

1000

0 2 4 6 8 10 12 14 16 18 20 22 24

Cor

rosio

n ra

te (m

py)

Time (hours)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)Figure 2 Variation of corrosion rate determined by RPL (real-timemonitoring) versus time for API X-70 steel exposed to 35NaCl solutionsaturated with CO2 at different concentrations of fatty amide (a) 30∘C (b) 50∘C and (c) 70∘C

It is observed that in the absence of inhibitor the corrosionrate of API X-70 steel is higher regardless of temperatureOnly at 70∘C it is observed that this tends to decreasemarkedly as a function of time This may be due to pre-cipitation of FeCO3 crystals onto steel surface In generalthis behavior is due to the electrochemical nature of thecorrosion process of carbon steel where both the anodic irondissolution and the cathodic evolution of hydrogen take place[22] The protection process (iron carbonate precipitation)is due to the CO2 hydration which causes the formation ofcarbonic acid

CO2 +H2O 997888rarr H2CO3 (1)Since the electrolyte is deaerated the possible dominantcathodic reactions can beH+ ions reduction water reduction

and the carbonic acid dissociation

2H+ + 2eminus 997888rarr H2 (2)

2H2O + 2eminus 997888rarr 2OHminus +H2 (3)

H2CO2 + eminus 997888rarr H+ +HCO3minus (4)

HCO3minus + eminus 997888rarr H+ + CO3minus2 (5)

And the primary anodic reaction is the dissolution of iron

Fe 997888rarr Fe+2 + 2eminus (6)

Journal of Chemistry 5

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

100 ppm50 ppm

(b)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

0 2 4 6 8 10 12 14 16 18 20 22 24Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

Addition of inhibitor

(c)

Figure 3 Variation of the inhibition efficiency determined from RPLmeasurements (real-timemonitoring) (a) 30∘C (b) 50∘C and (c) 70∘C

During the steel corrosion process the iron carbonate precip-itation onto steel surface is possible according to

Fe+2 + CO3minus2 997888rarr FeCO3 (7)

FeCO3 precipitation modifies the corrosion process kinet-ics because a physical porous barrier is formed betweenthe electrolyte and metal surface This barrier influencesthe transport of the corrosive species of the electrolyteHowever the protection of this porous layer depends onseveral environmental conditions such as iron concentrationpH solution temperature CO2 partial pressure mechanicalforces due to flow conditions and steel microstructure [23]Due to the imperfect nature of this protective scale (cracksand porosity) the electrolyte can permeate to the metal

surface and corrode the steel causing the detachment of theprotective scale [24] Therefore the protection provided bythe precipitation of iron carbonate is limited

On the other hand in the inhibitorrsquos presence the corro-sion rate decreases as its concentration increases regardlessof the test temperature At the maximum concentration ofinhibitor a reduction of one order of magnitude in thecorrosion rate is observed In all cases a drastic drop in thecorrosion rate values is observed in the first 3-4 hours afterthe inhibitor has been added subsequently the corrosionrate tends to decrease slowly without reaching a definedsteady state This reduction in the corrosion rate is due tothe adsorption of an inhibitor film onto steel surface whichacts as a more effective barrier to permeation of the corrosiveelectrolyte towards the metal surface The effectiveness of an

6 Journal of Chemistry

Addition of inhibitor

01

1

10

100

1000Co

rros

ion

rate

(mpy

)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Corr

osio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

1

10

100

1000

Corr

osio

n ra

te (m

py)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(c)Figure 4 Variation of corrosion rate as determined by HDA (real-timemonitoring) versus time for API X-70 steel exposed to CO2-saturatedsaline solution at different inhibitor concentration (a) 30∘C (b) 50∘C and (c) 70∘C

inhibitor of organic nature is the result of the physicochemicalproperties of themolecule the nature of its functional groupspossible steric effects and the electron density of the donoratoms [9] Inhibitor adsorption depends on the interaction ofthe120587 orbitals of the inhibitormolecule with the orbitals of theatoms of the metal surface [9]

Figure 3 shows the variation of the inhibition efficiencyof fatty amides as a function of time (from the RPL measure-ments of Figure 2) The inhibition efficiency was determinedaccording to the following relation

119864 () = CR119894 minus CR119887CR119894

lowast 100 (8)

where CR119887 is the corrosion rate in inhibitor absence andCR119894 when the inhibitor is present In all cases the inhibitionefficiency increased with the added inhibitor concentrationregardless of test temperature The inhibition efficiency wasgreater than 95 at the maximum inhibitor concentrationevaluated and in all cases the steady state was not reachedThis implies that in longer periods of exposure the inhibitionefficiency would tend to increase

Figure 4 shows the variation in the corrosion rate deter-mined from the HDA measurements as a function of timefor the API X-70 steel exposed in CO2-saturated salinesolution at 30 50 and 70∘C at different concentrationsof inhibitor The analysis of harmonics and the nonlinearresponse are based on the disturbance of anAC signal and the

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 3

100

90

80

70

60

4000 3500 3000 2500 2000 1500 1000 500

Wavenumber (cmminus1)

Tran

smitt

ance

()

2851

69

3254

13

3079

52

3008

36

1740

78

1649

32

1624

07

1558

89

1461

19

1375

92

1398

72

1270

11

1233

46

1054

49

1121

46

1171

16

921

6184

162 773

8371

876

555

28

2921

12

(a)

3298

66

3009

10

2851

95

2921

17

1640

30 1557

64 1462

75

1374

83 13

056

912

072

311

547

211

218

111

057

010

617

9

883

22

718

20

921

8495

786

625

8056

834

500

5541

460

1265

02

3272

90

100

90

80

70

60

4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

Wavenumber (cmminus1)

(b)

Figure 1 FT-IR spectra of the synthesis of the fatty amides from CRBO and AEEA (a) initial mixture (119905 = 0 minutes reaction) and (b) finalmixture (80 minutes reaction)

3 Results and Discussion

31 Synthesis of Fatty Amides Rice bran analysis indicated acrude oil content of 21 (dry basis) which is in agreementwith data reported in the literature [16ndash18] Its molecularweight calculated from its saponification index was 92336and its chemical characterization showed an oleic acid con-tent of 4848 3526 of linoleic acid and 1454 of palmiticacid similar values to those reported in the literature forthis type of oil [16 17] Knowledge of the type of fatty acidspresent in the oil is important given that both the lengthand unsaturation of the hydrocarbon chain contribute to themode of adsorption and inhibition efficiency of the inhibitormolecule [7]

Figure 1 shows the FT-IR spectra of the fatty amidessynthesized from CRBO and AEEA From Figure 1 it can beseen that the signal at 1740 cmminus1 corresponding to the C=Ostretching of the triglycerides disappears and a new signalis observed at 1640 cmminus1 It is known that the presence of

this signal is characteristic of the peaks corresponding to theamidation product (fatty amides) [10ndash19] Evolution of theFT-IR spectra at different times (spectra not shown) indicatedthat after 80minutes of reaction the complete disappearanceof the triglycerides was achieved suggesting formation offatty amides

32 Real-Time Corrosion Measurements of Synthesized FattyAmides Figure 2 shows the effect of the inhibitor addition(fatty amide) on the corrosion rate (based on RPL mea-surements) of API X-70 steel immersed in CO2-saturatedsaline solution at different test temperatures In all cases theinhibitor was added 60 minutes after the measurements werestarted RPL measurement involves measuring the polariza-tion resistance (Rp) using a sinusoidal polarization of smallamplitude (plusmn20mV) of the working electrode (steel understudy) In this case the slope of the potential-current sweep isRp which is inversely proportional to the corrosion currentdensity and it is subsequently transformed to corrosion rate

4 Journal of Chemistry

Addition of inhibitor

1

10

100

Cor

rosio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(a)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Cor

rosio

n ra

te (m

py)

(b)

1

10

100

1000

0 2 4 6 8 10 12 14 16 18 20 22 24

Cor

rosio

n ra

te (m

py)

Time (hours)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)Figure 2 Variation of corrosion rate determined by RPL (real-timemonitoring) versus time for API X-70 steel exposed to 35NaCl solutionsaturated with CO2 at different concentrations of fatty amide (a) 30∘C (b) 50∘C and (c) 70∘C

It is observed that in the absence of inhibitor the corrosionrate of API X-70 steel is higher regardless of temperatureOnly at 70∘C it is observed that this tends to decreasemarkedly as a function of time This may be due to pre-cipitation of FeCO3 crystals onto steel surface In generalthis behavior is due to the electrochemical nature of thecorrosion process of carbon steel where both the anodic irondissolution and the cathodic evolution of hydrogen take place[22] The protection process (iron carbonate precipitation)is due to the CO2 hydration which causes the formation ofcarbonic acid

CO2 +H2O 997888rarr H2CO3 (1)Since the electrolyte is deaerated the possible dominantcathodic reactions can beH+ ions reduction water reduction

and the carbonic acid dissociation

2H+ + 2eminus 997888rarr H2 (2)

2H2O + 2eminus 997888rarr 2OHminus +H2 (3)

H2CO2 + eminus 997888rarr H+ +HCO3minus (4)

HCO3minus + eminus 997888rarr H+ + CO3minus2 (5)

And the primary anodic reaction is the dissolution of iron

Fe 997888rarr Fe+2 + 2eminus (6)

Journal of Chemistry 5

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

100 ppm50 ppm

(b)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

0 2 4 6 8 10 12 14 16 18 20 22 24Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

Addition of inhibitor

(c)

Figure 3 Variation of the inhibition efficiency determined from RPLmeasurements (real-timemonitoring) (a) 30∘C (b) 50∘C and (c) 70∘C

During the steel corrosion process the iron carbonate precip-itation onto steel surface is possible according to

Fe+2 + CO3minus2 997888rarr FeCO3 (7)

FeCO3 precipitation modifies the corrosion process kinet-ics because a physical porous barrier is formed betweenthe electrolyte and metal surface This barrier influencesthe transport of the corrosive species of the electrolyteHowever the protection of this porous layer depends onseveral environmental conditions such as iron concentrationpH solution temperature CO2 partial pressure mechanicalforces due to flow conditions and steel microstructure [23]Due to the imperfect nature of this protective scale (cracksand porosity) the electrolyte can permeate to the metal

surface and corrode the steel causing the detachment of theprotective scale [24] Therefore the protection provided bythe precipitation of iron carbonate is limited

On the other hand in the inhibitorrsquos presence the corro-sion rate decreases as its concentration increases regardlessof the test temperature At the maximum concentration ofinhibitor a reduction of one order of magnitude in thecorrosion rate is observed In all cases a drastic drop in thecorrosion rate values is observed in the first 3-4 hours afterthe inhibitor has been added subsequently the corrosionrate tends to decrease slowly without reaching a definedsteady state This reduction in the corrosion rate is due tothe adsorption of an inhibitor film onto steel surface whichacts as a more effective barrier to permeation of the corrosiveelectrolyte towards the metal surface The effectiveness of an

6 Journal of Chemistry

Addition of inhibitor

01

1

10

100

1000Co

rros

ion

rate

(mpy

)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Corr

osio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

1

10

100

1000

Corr

osio

n ra

te (m

py)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(c)Figure 4 Variation of corrosion rate as determined by HDA (real-timemonitoring) versus time for API X-70 steel exposed to CO2-saturatedsaline solution at different inhibitor concentration (a) 30∘C (b) 50∘C and (c) 70∘C

inhibitor of organic nature is the result of the physicochemicalproperties of themolecule the nature of its functional groupspossible steric effects and the electron density of the donoratoms [9] Inhibitor adsorption depends on the interaction ofthe120587 orbitals of the inhibitormolecule with the orbitals of theatoms of the metal surface [9]

Figure 3 shows the variation of the inhibition efficiencyof fatty amides as a function of time (from the RPL measure-ments of Figure 2) The inhibition efficiency was determinedaccording to the following relation

119864 () = CR119894 minus CR119887CR119894

lowast 100 (8)

where CR119887 is the corrosion rate in inhibitor absence andCR119894 when the inhibitor is present In all cases the inhibitionefficiency increased with the added inhibitor concentrationregardless of test temperature The inhibition efficiency wasgreater than 95 at the maximum inhibitor concentrationevaluated and in all cases the steady state was not reachedThis implies that in longer periods of exposure the inhibitionefficiency would tend to increase

Figure 4 shows the variation in the corrosion rate deter-mined from the HDA measurements as a function of timefor the API X-70 steel exposed in CO2-saturated salinesolution at 30 50 and 70∘C at different concentrationsof inhibitor The analysis of harmonics and the nonlinearresponse are based on the disturbance of anAC signal and the

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

4 Journal of Chemistry

Addition of inhibitor

1

10

100

Cor

rosio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(a)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Cor

rosio

n ra

te (m

py)

(b)

1

10

100

1000

0 2 4 6 8 10 12 14 16 18 20 22 24

Cor

rosio

n ra

te (m

py)

Time (hours)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)Figure 2 Variation of corrosion rate determined by RPL (real-timemonitoring) versus time for API X-70 steel exposed to 35NaCl solutionsaturated with CO2 at different concentrations of fatty amide (a) 30∘C (b) 50∘C and (c) 70∘C

It is observed that in the absence of inhibitor the corrosionrate of API X-70 steel is higher regardless of temperatureOnly at 70∘C it is observed that this tends to decreasemarkedly as a function of time This may be due to pre-cipitation of FeCO3 crystals onto steel surface In generalthis behavior is due to the electrochemical nature of thecorrosion process of carbon steel where both the anodic irondissolution and the cathodic evolution of hydrogen take place[22] The protection process (iron carbonate precipitation)is due to the CO2 hydration which causes the formation ofcarbonic acid

CO2 +H2O 997888rarr H2CO3 (1)Since the electrolyte is deaerated the possible dominantcathodic reactions can beH+ ions reduction water reduction

and the carbonic acid dissociation

2H+ + 2eminus 997888rarr H2 (2)

2H2O + 2eminus 997888rarr 2OHminus +H2 (3)

H2CO2 + eminus 997888rarr H+ +HCO3minus (4)

HCO3minus + eminus 997888rarr H+ + CO3minus2 (5)

And the primary anodic reaction is the dissolution of iron

Fe 997888rarr Fe+2 + 2eminus (6)

Journal of Chemistry 5

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

100 ppm50 ppm

(b)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

0 2 4 6 8 10 12 14 16 18 20 22 24Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

Addition of inhibitor

(c)

Figure 3 Variation of the inhibition efficiency determined from RPLmeasurements (real-timemonitoring) (a) 30∘C (b) 50∘C and (c) 70∘C

During the steel corrosion process the iron carbonate precip-itation onto steel surface is possible according to

Fe+2 + CO3minus2 997888rarr FeCO3 (7)

FeCO3 precipitation modifies the corrosion process kinet-ics because a physical porous barrier is formed betweenthe electrolyte and metal surface This barrier influencesthe transport of the corrosive species of the electrolyteHowever the protection of this porous layer depends onseveral environmental conditions such as iron concentrationpH solution temperature CO2 partial pressure mechanicalforces due to flow conditions and steel microstructure [23]Due to the imperfect nature of this protective scale (cracksand porosity) the electrolyte can permeate to the metal

surface and corrode the steel causing the detachment of theprotective scale [24] Therefore the protection provided bythe precipitation of iron carbonate is limited

On the other hand in the inhibitorrsquos presence the corro-sion rate decreases as its concentration increases regardlessof the test temperature At the maximum concentration ofinhibitor a reduction of one order of magnitude in thecorrosion rate is observed In all cases a drastic drop in thecorrosion rate values is observed in the first 3-4 hours afterthe inhibitor has been added subsequently the corrosionrate tends to decrease slowly without reaching a definedsteady state This reduction in the corrosion rate is due tothe adsorption of an inhibitor film onto steel surface whichacts as a more effective barrier to permeation of the corrosiveelectrolyte towards the metal surface The effectiveness of an

6 Journal of Chemistry

Addition of inhibitor

01

1

10

100

1000Co

rros

ion

rate

(mpy

)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Corr

osio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

1

10

100

1000

Corr

osio

n ra

te (m

py)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(c)Figure 4 Variation of corrosion rate as determined by HDA (real-timemonitoring) versus time for API X-70 steel exposed to CO2-saturatedsaline solution at different inhibitor concentration (a) 30∘C (b) 50∘C and (c) 70∘C

inhibitor of organic nature is the result of the physicochemicalproperties of themolecule the nature of its functional groupspossible steric effects and the electron density of the donoratoms [9] Inhibitor adsorption depends on the interaction ofthe120587 orbitals of the inhibitormolecule with the orbitals of theatoms of the metal surface [9]

Figure 3 shows the variation of the inhibition efficiencyof fatty amides as a function of time (from the RPL measure-ments of Figure 2) The inhibition efficiency was determinedaccording to the following relation

119864 () = CR119894 minus CR119887CR119894

lowast 100 (8)

where CR119887 is the corrosion rate in inhibitor absence andCR119894 when the inhibitor is present In all cases the inhibitionefficiency increased with the added inhibitor concentrationregardless of test temperature The inhibition efficiency wasgreater than 95 at the maximum inhibitor concentrationevaluated and in all cases the steady state was not reachedThis implies that in longer periods of exposure the inhibitionefficiency would tend to increase

Figure 4 shows the variation in the corrosion rate deter-mined from the HDA measurements as a function of timefor the API X-70 steel exposed in CO2-saturated salinesolution at 30 50 and 70∘C at different concentrationsof inhibitor The analysis of harmonics and the nonlinearresponse are based on the disturbance of anAC signal and the

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 5

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

100 ppm50 ppm

(b)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

0 2 4 6 8 10 12 14 16 18 20 22 24Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

Addition of inhibitor

(c)

Figure 3 Variation of the inhibition efficiency determined from RPLmeasurements (real-timemonitoring) (a) 30∘C (b) 50∘C and (c) 70∘C

During the steel corrosion process the iron carbonate precip-itation onto steel surface is possible according to

Fe+2 + CO3minus2 997888rarr FeCO3 (7)

FeCO3 precipitation modifies the corrosion process kinet-ics because a physical porous barrier is formed betweenthe electrolyte and metal surface This barrier influencesthe transport of the corrosive species of the electrolyteHowever the protection of this porous layer depends onseveral environmental conditions such as iron concentrationpH solution temperature CO2 partial pressure mechanicalforces due to flow conditions and steel microstructure [23]Due to the imperfect nature of this protective scale (cracksand porosity) the electrolyte can permeate to the metal

surface and corrode the steel causing the detachment of theprotective scale [24] Therefore the protection provided bythe precipitation of iron carbonate is limited

On the other hand in the inhibitorrsquos presence the corro-sion rate decreases as its concentration increases regardlessof the test temperature At the maximum concentration ofinhibitor a reduction of one order of magnitude in thecorrosion rate is observed In all cases a drastic drop in thecorrosion rate values is observed in the first 3-4 hours afterthe inhibitor has been added subsequently the corrosionrate tends to decrease slowly without reaching a definedsteady state This reduction in the corrosion rate is due tothe adsorption of an inhibitor film onto steel surface whichacts as a more effective barrier to permeation of the corrosiveelectrolyte towards the metal surface The effectiveness of an

6 Journal of Chemistry

Addition of inhibitor

01

1

10

100

1000Co

rros

ion

rate

(mpy

)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Corr

osio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

1

10

100

1000

Corr

osio

n ra

te (m

py)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(c)Figure 4 Variation of corrosion rate as determined by HDA (real-timemonitoring) versus time for API X-70 steel exposed to CO2-saturatedsaline solution at different inhibitor concentration (a) 30∘C (b) 50∘C and (c) 70∘C

inhibitor of organic nature is the result of the physicochemicalproperties of themolecule the nature of its functional groupspossible steric effects and the electron density of the donoratoms [9] Inhibitor adsorption depends on the interaction ofthe120587 orbitals of the inhibitormolecule with the orbitals of theatoms of the metal surface [9]

Figure 3 shows the variation of the inhibition efficiencyof fatty amides as a function of time (from the RPL measure-ments of Figure 2) The inhibition efficiency was determinedaccording to the following relation

119864 () = CR119894 minus CR119887CR119894

lowast 100 (8)

where CR119887 is the corrosion rate in inhibitor absence andCR119894 when the inhibitor is present In all cases the inhibitionefficiency increased with the added inhibitor concentrationregardless of test temperature The inhibition efficiency wasgreater than 95 at the maximum inhibitor concentrationevaluated and in all cases the steady state was not reachedThis implies that in longer periods of exposure the inhibitionefficiency would tend to increase

Figure 4 shows the variation in the corrosion rate deter-mined from the HDA measurements as a function of timefor the API X-70 steel exposed in CO2-saturated salinesolution at 30 50 and 70∘C at different concentrationsof inhibitor The analysis of harmonics and the nonlinearresponse are based on the disturbance of anAC signal and the

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

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Analytical Methods in Chemistry

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Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

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Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

6 Journal of Chemistry

Addition of inhibitor

01

1

10

100

1000Co

rros

ion

rate

(mpy

)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

1

10

100

1000

Corr

osio

n ra

te (m

py)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

1

10

100

1000

Corr

osio

n ra

te (m

py)

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

(c)Figure 4 Variation of corrosion rate as determined by HDA (real-timemonitoring) versus time for API X-70 steel exposed to CO2-saturatedsaline solution at different inhibitor concentration (a) 30∘C (b) 50∘C and (c) 70∘C

inhibitor of organic nature is the result of the physicochemicalproperties of themolecule the nature of its functional groupspossible steric effects and the electron density of the donoratoms [9] Inhibitor adsorption depends on the interaction ofthe120587 orbitals of the inhibitormolecule with the orbitals of theatoms of the metal surface [9]

Figure 3 shows the variation of the inhibition efficiencyof fatty amides as a function of time (from the RPL measure-ments of Figure 2) The inhibition efficiency was determinedaccording to the following relation

119864 () = CR119894 minus CR119887CR119894

lowast 100 (8)

where CR119887 is the corrosion rate in inhibitor absence andCR119894 when the inhibitor is present In all cases the inhibitionefficiency increased with the added inhibitor concentrationregardless of test temperature The inhibition efficiency wasgreater than 95 at the maximum inhibitor concentrationevaluated and in all cases the steady state was not reachedThis implies that in longer periods of exposure the inhibitionefficiency would tend to increase

Figure 4 shows the variation in the corrosion rate deter-mined from the HDA measurements as a function of timefor the API X-70 steel exposed in CO2-saturated salinesolution at 30 50 and 70∘C at different concentrationsof inhibitor The analysis of harmonics and the nonlinearresponse are based on the disturbance of anAC signal and the

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

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Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

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Quantum Chemistry

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Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 7

Addition of inhibitor

minus100

102030405060708090

100In

hibi

tion

effici

ency

()

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(b)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

minus100

102030405060708090

100

Inhi

bitio

n effi

cien

cy (

)

5 ppm10 ppm25 ppm

50 ppm100 ppm

(c)

Figure 5 Variation of inhibition efficiency determined from HDA-based measurements (real-time monitoring) (a) 30∘C (b) 50∘C and (c)70∘C

frequency domain correspondingly The latter is a measureof the nonlinear current distortion originated during theRPL measurement using a 10mHz sine wave (50mV peak-to-peak) and analyzes current signals at 10 20 and 30mHzThis allows obtaining the kinetic parameters of the corrosionprocessTheharmonics analysis in the current response offersthe possibility of obtaining the corrosion rate and the anodicand cathodic parameters of Tafel

In general the corrosion rates obtained from the HDA-basedmeasurements suggest a similar trend to those obtainedfrom the RPL measurements The possible differencesobserved are due to the fact that for the calculation of thecorrosion rate the HDA technique uses instantaneous valuesof the anodic and cathodic Tafel slopes and in RPL-based

measurements (Figure 2) the technique uses fixed values(120mV) Observation of disturbances in the measurementsis notorious and their magnitude increases with the temper-ature and evenmore when the inhibitor is present Since suchperturbations can be interpreted as adsorption-desorptionprocesses of the inhibitor molecules and these processespromote the presence of active sites onto metal surface bothcorrosion potential values (119864corr) andTafel kinetic parameterscan be affected [7]

Thus the calculation of the corrosion rate to use instan-taneous Tafel values is advisable Employing constant valueswill show a smoothed trend which suppresses the transientprocesses In this sense it can be observed that the amplitudeof the transients increases with the temperature and for

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

8 Journal of Chemistry

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(a)

Addition of inhibitor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

0001

001

01

1

Pitti

ng fa

ctor

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

Addition of inhibitor

0001

001

01

1

Pitti

ng fa

ctor

2 4 6 8 10 12 14 16 18 20 22 240Time (hours)

Blank5 ppm10 ppm

25 ppm50 ppm100 ppm

(c)

Figure 6 Variation in PF values as a function of time for API X-70 steel exposed to CO2-saturated saline solution at different inhibitor

concentrations (a) 30∘C (b) 50∘C and (c) 70∘C

a given temperature decreases with the inhibitor concen-tration This suggests two facts (1) the inhibitor moleculesadsorption can be compromised by increasing temperatureand (2) when the inhibitor concentration is increased thereare a greater number of molecules occupying the active sitesleft by the desorption of the inhibitor molecules

Similarly the evolution of the inhibition efficiency fromthe HDA-based corrosion rate measurements (Figure 4) isshown in Figure 5 As indicated the observed transients canbe interpreted as a measure of the adsorption stability of theinhibitor molecules onto metal surface Mainly increasingthe inhibitor concentration decreases both the amplitude andfrequency of the instabilities

Figure 6 shows the variation of pitting factor (PF) asa function of time for API X-70 steel exposed to CO2-saturated saline solution at different test temperatures withand without inhibitor addition This parameter is obtainedfromENandHDAmeasurements where EN refers to currentand potential fluctuations that occur onto steel surface with-out disturbance of its potential EN measurements provideinformation on the activity level of the corrosion processand the dominant corrosion mechanism The pitting factoris defined as follows [25]

PF = 120590119868EN119860WE119868HA (9)

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 9

minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

0001000020000

Pote

ntia

l (m

V v

s Pt)

000001 00001 0001 001 01 1 10 100

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(a)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

000001 00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

Current density (mAcm2)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

(b)

minus90000minus80000minus70000minus60000minus50000minus40000minus30000minus20000minus10000

00010000

00001 0001 001 01 1 10 100

Pote

ntia

l (m

V v

s Pt)

0 ppm5 ppm10 ppm

25 ppm50 ppm100 ppm

Current density (mAcm2)

(c)Figure 7 Potentiodynamic polarization curves for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor(a) 30∘C (b) 50∘C and (c) 70∘C after 24 hours of stabilization

where 120590119868EN is the standard deviation of the current (deter-mined by electrochemical noise) 119860WE is the steel reactionarea cm2 and 119868HA is the corrosion current density obtainedfrom harmonic analysis in Acm2 The PF is an index whichvaries within 0-1 and is an estimate of the localized attackPF values are interpreted as follows PF values lt 001 suggestgeneralized corrosion in the range of 001ndash010 generalizedcorrosion dominates in an intermediate zone and values gt01 imply localized corrosion

According to Figure 6 in the absence of inhibitors thePF values decrease as the temperature increases whereasat a given temperature the PF values tendency decreases asthe immersion time increases In all cases PF values movefrom the region of generalized corrosion with pitting attackto the region of uniform corrosion This is expected becausethe FeCO3 precipitation onto steel surface gives it someprotection and this precipitation is favored by increasing

the temperature However in the inhibitorrsquos presence weobserved that the PF values are lower as the inhibitorconcentration increases in every case (lower values than thoseobserved without presence of inhibitor) reaching values ofuniform corrosion In addition it was observed that thefluctuations in PF values were higher if the temperatureincreased This is possible due to the adsorption-desorptionprocesses of the inhibitor molecules

33 Polarization Curves Figure 7 shows the polarizationcurves of API X-70 steel in CO2-saturated saline solution anddifferent inhibitor concentrations at 30∘C 50∘C and 70∘Crespectively These tests show whether the material understudy shows active passive or transpassive behavior [26] Inthe absence of inhibitor the tendency of the anodic branchshows that the steel undergoes a continuous dissolutionprocess and that the steel dissolution increases with the test

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

10 Journal of Chemistry

minus600

minus550

minus500

minus450

minus400

minus350

minus300

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

Eco

rr(m

V v

s Pt)

(a)

0

50

100

150

200

250

Ba (m

VD

ec)

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(b)

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

Bc (m

VD

ec)

Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

(c)

0

002

004

006

008

01

012

014

016

0 10 20 30 40 50 60 70 80 90 100Inhibitor concentration (ppm)

30∘C

50∘C

70∘C

I corr

(mA

cm

2)

(d)

Figure 8 Electrochemical parameters for API X-70 steel in CO2-saturated saline solution as a function of inhibitor concentration andtemperature (a) corrosion potential (b) anodic slope (c) cathodic slope and (d) corrosion current density

temperature It has been suggested that the Fe dissolution canoccur according to the following reactions [27 28]

Fe +H2Olarrrarr FeOHads +H+ + eFeOHads 997888rarr FeOH+ + e

FeOH+ +H+ larrrarr Fe2+ +H2O(10)

where the global reaction of anodic dissolution is thatrepresented by (6) [29 30]

The observed behavior shows that the steel does not havethe ability to form a passive layer that protects it from theaggressive environment that is its corrosion products arenot protective At temperatures higher than 50∘C and longestexposure times the precipitation of an iron carbonate layer

onto steel surface is possible according to (7) However theFeCO3 layer offers limited protection due to the presence ofimperfections (porosity and cracks) whereby the electrolytecan penetrate and corrode the steel surface causing itsdetachment [24]

However when the inhibitor is added there is an increasein the slope of the anodic branch indicating a decrease in theactive behavior and 119864corr values move towards nobler valuesexcept at 30∘C where with 10 ppm and 25 ppm of inhibitora shift towards more active values was observed This maybe due to the low test temperature which did not facilitatethe optimal dispersion of the inhibitor The dispersion of theinhibitor is favored by increasing the temperature facilitatingits transport towards the metal surface Similarly in the pres-ence of the inhibitor the polarization curves moved towards

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 11

minus6

minus55

minus5

minus45

minus4

minus35

minus3

minus25

minus2

minus15

minus1

000034 000035 000036 000037 000038 000039 000041RT

100 ppm50 ppm25 ppm

10 ppm5 ppm0 ppm

lnI c

orr

Figure 9 ln(119868corr) - 1119877119879 relationship for the API X-70 steel evaluated in CO2-saturated saline solution as a function of the inhibitorconcentration

the lower current density region indicating a decrease inthe corrosion rate of the steel On the other hand it isobserved that the cathodic branch shows the same shape andtrend at all temperatures This indicates that the reductionreaction is the same and it is activated thermally since byincreasing the temperature the cathodic branch moves tohigher current densities Because the solution is deaerated(continuous bubbling of CO2 CO2 + H2O = H2CO3) themain possible cathodic reactions are the H+ ions reductionthe carbonic acid dissociation and the water reduction [2229 30] according to (2)ndash(5)

Figure 8 shows the evolution of the electrochemicalparameters obtained from Figure 7 It is observed thatthe tendency of the 119864corr values (Figure 8(a)) is identicalregardless of the test temperature In general in presenceof the inhibitor the 119864corr values are nobler and they tendto increase as a function of the inhibitor concentration Atthe same time 119864corr values are more active by increasingthe temperature this is because the corrosion phenomenonis a thermally activated process The tendency in the 119864corrvalues allows assuming that the inhibitor evaluated is ofthe anodic type and that its main action is to suppress theanodic reaction (Fe dissolution) This is supported by theevolution of the anodic slope values (Figure 8(b)) where itis observed that these values are higher than those observedin the absence of inhibitor Figure 8(c) shows a similar trendin the cathodic slope values that is the values increase byincreasing temperature This is congruent with the dissolvedCO2 content The content of dissolved CO2 is a functionof temperature solutes concentration and pressure that isincreasing the temperature decreases the amount of dissolvedCO2 and therefore increases the cathodic slope This is afeature of processes controlled by mass transfer [31 32] Thesame occurs with the dissolved O2 in the solution In generalat 30∘C the values tend to increase with the inhibitor con-centration and at higher temperatures the opposite occurs

Figure 8(d) shows that the steel corrosion rate decreases asthe inhibitor concentration increases This is congruent withthe observed from the real-time measurements discussedpreviously

The dependence of the metal dissolution rate on temper-ature can be explained using the Arrhenius equation wherethe activation energy of the metal dissolution process can becalculated according to [27]

119868corr = 119896 exp (minusΔ119864119877119879)

ln (119868corr) = ln 119896 minus Δ119864119877119879(11)

whereΔ119864 (Jmolminus1) is the activation energy which is obtainedfrom the slope of the ln(119868corr) versus 1119877119879 relationship119896 is a constant and 119877 is the gas constant (8314472 JK-mol) Figure 9 shows the ln(119868corr) versus 1119877119879 relationshipas a function of inhibitor concentration The calculatedactivation energies were 445 4535 4831 5155 5230 and5231 kJmolminus1 for 0 5 10 25 50 and 100 ppm respectivelyThis indicates that the anodic reaction is affected by thepresence of the inhibitor and that the Fe dissolution ratedecreases by increasing the concentration of the inhibitorIn the absence of inhibitor activation energy values of theorder of 14ndash30 kJmolminus1 are reported [27 33] Such values arelower than those determined in this study nevertheless thefundamental difference is the type of steel evaluated and theNaCl content of the electrolyte

In order to verify the decrease in Fe dissolution rateadditional experiments based on electrochemical impedancespectroscopy (EIS) measurements were performed Figure 10shows the evolution of the EIS spectra as a function ofinhibitor concentration after 24 hours of immersion in theelectrolyte From the figure it is clear that in the presenceof the inhibitor the magnitude of the capacitive semicircle

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

12 Journal of Chemistry

minus9000

minus8000

minus7000

minus6000

minus5000

minus4000

minus3000

minus2000

minus1000

00 1000 2000 3000 4000 5000 6000 7000 8000 9000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(a)

minus3000

minus2500

minus2000

minus1500

minus1000

minus500

00 500 1000 1500 2000 2500 3000

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(b)minus1800

minus1600

minus1400

minus1200

minus1000

minus800

minus600

minus400

minus200

00 200 400 600 800 1000 1200 1400 1600 1800

Z㰀㰀 (Ohm-cm2

)

Z㰀㰀

(Ohm

-cm

2)

100 ppm50 ppm25 ppmBlank

10 ppm5 ppm

(c)

Figure 10 EIS spectra for API X-70 steel in CO2-saturated saline solution at different concentrations of inhibitor (a) 30∘C (b) 50∘C and (c)70∘C after 24 hours of immersion

increases and likewise its diameter also increases by increas-ing the inhibitor concentration This shows that the chargetransfer resistance of the steel increases and consequentlydecreases its dissolution rate [6 7]

The fatty amides synthesized from the crude rice branoil act as corrosion inhibitors due to the high unsaturationcontent of their alkyl chains In short the inhibitory efficacywas excellent This allows the adsorption of the inhibitormolecule ontometal surface thereby decreasing its corrosionrate independently of the test temperature The above resultsdemonstrate that the use of agroindustrial byproducts (ricebran) is a sustainable source for the synthesis of corrosioninhibitors Notwithstanding the foregoing in the scientificliterature there are few studies that take into account the

byproducts of the rice milling process as an important sourcefor the synthesis of green corrosion inhibitors for examplethe use of the rice husk as raw material for obtainingnanosilicate [34] tannins [35] and momilactone A [36] andthe use of rice bran for the extraction of phytic acid have beenreported [37ndash39] and only one study reported the use of ricebran oil for synthesis of fatty acid triazoles [40]

4 Conclusions

Crude rice bran oil is a promising source for the synthesis ofbioproducts such as fatty acid amides The unsaturated fattyacid content of crude rice bran oil makes it an ideal candidatefor the synthesis of corrosion inhibitors The electrochemical

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Journal of Chemistry 13

evaluations performed showed that the fatty amides actedas corrosion inhibitors at all test temperatures In all casesthe inhibition efficiency was at least 95 for the optimuminhibitor concentration From the real-timemeasurements itwas observed that in the presence of the inhibitor the pittingfactor valueswere lower than those observed in the absence ofinhibitor This is attributed to the adsorption of the inhibitormolecule onto metal surface which prevented the diffusionof the aggressive ions of the electrolyte Calculation of theactivation energy of the corrosion process showed that theinhibitor suppresses the anodic reaction and that this effectincreases with the concentration of added inhibitor

Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

Financial support from Consejo Nacional de Ciencia y Tec-nologıa (CONACYT Mexico) (Project 159898) is gratefullyacknowledged E Reyes-Dorantes and J Zuniga-Dıaz thankCONACYTMexico for the financial support given to realizetheir postgraduate studies

References

[1] MHeydari andM Javidi ldquoCorrosion inhibition and adsorptionbehaviour of an amido-imidazoline derivative on API 5L X52steel in CO2-saturated solution and synergistic effect of iodideionsrdquo Corrosion Science vol 61 pp 148ndash155 2012

[2] M P Desimone G Gordillo and S N Simison ldquoThe effectof temperature and concentration on the corrosion inhibitionmechanism of an amphiphilic amido-amine in CO

2 saturatedsolutionrdquo Corrosion Science vol 53 no 12 pp 4033ndash4043 2011

[3] HMAbdEl-Lateef VMAbbasov L I Aliyeva E EQasimovand I T Ismayilov ldquoInhibition of carbon steel corrosion inCO2-saturated brine using some newly surfactants based on

palmoil experimental and theoretical investigationsrdquoMaterialsChemistry and Physics vol 142 no 2-3 pp 502ndash512 2013

[4] P B Raja andMG Sethuraman ldquoNatural products as corrosioninhibitor for metals in corrosive mediamdasha reviewrdquo MaterialsLetters vol 62 no 1 pp 113ndash116 2008

[5] V Jovancicevic S Ramachandran and P Prince ldquoInhibition ofcarbon dioxide corrosion ofmild steel by imidazolines and theirprecursorsrdquo Corrosion vol 55 pp 449ndash455 1999

[6] J Porcayo-Calderon L M Martınez De La Escalera J Cantoand M Casales-Diaz ldquoImidazoline derivatives based on coffeeoil as CO

2 corrosion inhibitorrdquo International Journal of Electro-chemical Science vol 10 pp 3160ndash3176 2015

[7] J Porcayo-Calderon I Regla E Vazquez-Velez et al ldquoEffectof the unsaturation of the hydrocarbon chain of fatty-amideson the CO

2-corrosion of carbon steel using EIS and real-time corrosionmeasurementrdquo Journal of Spectroscopy vol 2015Article ID 184140 10 pages 2015

[8] M Lopez J Porcayo-Calderon M Casales-Diaz et al ldquoInter-nal corrosion solution for gathering production gas pipelines

involving palm oil amide based corrosion inhibitorsrdquo Interna-tional Journal of Electrochemical Science vol 10 pp 7166ndash71792015

[9] S Godavarthi J Porcayo-Calderon M Casales-Diaz EVazquez-Velez A Neri and L Martinez-Gomez ldquoElectro-chemical analysis and quantum chemistry of castor oil-basedcorrosion inhibitorsrdquo Current Analytical Chemistry vol 12 pp476ndash488 2016

[10] S H Yoo Y W Kim K Chung S Y Baik and J S KimldquoSynthesis and corrosion inhibition behavior of imidazolinederivatives based on vegetable oilrdquo Corrosion Science vol 59pp 42ndash54 2012

[11] E E Ebenso U J Ekpe B I Ita O E Offiong and U J IbokldquoEffect of molecular structure on the efficiency of amides andthiosemicarbazones used for corrosion inhibition of mild steelin hydrochloric acidrdquoMaterials Chemistry and Physics vol 60no 1 pp 79ndash90 1999

[12] S Ramachandran B-L Tsai M Blanco H Chen Y TangandW A Goddard ldquoSelf-assembledmonolayer mechanism forcorrosion inhibition of iron by imidazolinesrdquo Langmuir vol 12no 26 pp 6419ndash6428 1996

[13] S Vyas and S Soni ldquoCastor oil as corrosion inhibitor for ironin hydrochloric acidrdquo Oriental Journal of Chemistry vol 27 pp1743ndash1746 2011

[14] M Alam D Akram E Sharmin F Zafar and S AhmadldquoVegetable oil based eco-friendly coating materials a reviewarticlerdquo Arabian Journal of Chemistry vol 7 no 4 pp 469ndash4792014

[15] L Canoira J Garcıa Galean R Alcantara M Lapuerta andR Garcıa-Contreras ldquoFatty acid methyl esters (FAMEs) fromcastor oil production process assessment and synergistic effectsin its propertiesrdquo Renewable Energy vol 35 no 1 pp 208ndash2172010

[16] L A Rigo A R Pohlmann S S Guterres and R C RBeck ldquoRice bran oil benefits to health and applications inpharmaceutical formulationsrdquo in Wheat and Rice in DiseasePrevention and Health Benefits Risks andMechanisms ofWholeGrains in Health Promotion R R Watson V Preedy and SZibadi Eds pp 311ndash322 Academic Press 2014

[17] K Gul B Yousuf A K Singh P Singh and A A Wani ldquoRicebran nutritional values and its emerging potential for devel-opment of functional foodmdasha reviewrdquo Bioactive Carbohydratesand Dietary Fibre vol 6 no 1 pp 24ndash30 2015

[18] S Bhosale and D Vijayakshmi ldquoProcessing and nutritionalcomposition of rice branrdquo Current Research in Nutrition andFood Science vol 3 pp 74ndash80 2015

[19] D Kumar S M Kim and A Ali ldquoOne step synthesis offatty acid diethanolamides and methyl esters from triglyceridesusing sodium doped calcium hydroxide as a nanocrystallineheterogeneous catalystrdquo New Journal of Chemistry vol 39 pp7097ndash7104 2015

[20] R D Kane and S Campbell ldquoReal-time corrosion monitoringof steel influenced by microbial activity (SRB) in simulatedseawater injection environmentsrdquo Corrosion2004 TX NACEInternational Houston Texas

[21] D C Eden D A Eden I G Winning and D Fell ldquoOn-line real-time optimization of corrosion inhibitors in thefieldrdquo Corrosion2006 TX NACE International San DiegoCalifornia 12ndash16 March 2006

[22] X Liu Y G Zheng and P COkafor ldquoCarbon dioxide corrosioninhibition of N80 carbon steel in single liquid phase and

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

14 Journal of Chemistry

liquidparticle two-phase flow by hydroxyethyl imidazolinederivativesrdquoMaterials and Corrosion vol 60 no 7 pp 507ndash5132009

[23] F Farelas M Galicia B Brown S Nesic and H CastanedaldquoEvolution of dissolution processes at the interface of carbonsteel corroding in aCO

2 environment studied by EISrdquoCorrosionScience vol 52 no 2 pp 509ndash517 2010

[24] S L Wu Z D Cui F He Z Q Bai S L Zhu and X JYang ldquoCharacterization of the surface film formed from carbondioxide corrosion on N80 steelrdquoMaterials Letters vol 58 no 6pp 1076ndash1081 2004

[25] J Tinnea B S Covino S J Bullard et al ldquoElectrochemicaltechniques investigation of corrosion in a major metropolitanwastewater treatment facilityrdquo Corrosion2004 NACE Interna-tional Houston Texas March 2004

[26] B G Ateya F M Al Kharafi and R M Abdalla ldquoElectro-chemical behavior of low carbon steel in slightly acidic brinesrdquoMaterials Chemistry and Physics vol 78 no 2 pp 534ndash5412002

[27] G Zhang C Chen M Lu C Chai and Y Wu ldquoEvaluationof inhibition efficiency of an imidazoline derivative in CO

2-containing aqueous solutionrdquoMaterials Chemistry and Physicsvol 105 no 2-3 pp 331ndash340 2007

[28] J O Bockris and D Drazic ldquoThe kinetics of deposition anddissolution of iron effect of alloying impuritiesrdquo ElectrochimicaActa vol 7 no 3 pp 293ndash313 1962

[29] D A Lopez T Perez and S N Simison ldquoThe influence ofmicrostructure and chemical composition of carbon and lowalloy steels in CO

2 corrosion A state-of-the-art appraisalrdquoMaterials and Design vol 24 no 8 pp 561ndash575 2003

[30] H M Ezuber ldquoInfluence of temperature and thiosulfate on thecorrosion behavior of steel in chloride solutions saturated inCO2rdquoMaterials and Design vol 30 no 9 pp 3420ndash3427 2009

[31] X Liu P C Okafor and Y G Zheng ldquoThe inhibition ofCO2 corrosion of N80 mild steel in single liquid phaseand liquidparticle two-phase flow by aminoethyl imidazolinederivativesrdquo Corrosion Science vol 51 no 4 pp 744ndash751 2009

[32] L M Rivera-Grau M Casales I Regla et al ldquoEffect of organiccorrosion inhibitors on the corrosion performance of 1018carbon steel in 3 NaCl solutionrdquo International Journal ofElectrochemical Science vol 8 pp 2491ndash2503 2013

[33] J Porcayo-Calderon L M Martınez de la Escalera J CantoM Casales-Diaz and V M Salinas-Bravo ldquoEffect of theTemperature on the CO

2-Corrosion of Ni3Alrdquo in Proceedingsof International Journal of Electrochemical Science vol 10 pp3136ndash3151 2015

[34] D A Awizar N K Othman A Jalar A R Daud I ARahman and N H Al-Hardan ldquoNanosilicate extraction fromrice husk ash as green corrosion inhibitorrdquo International Journalof Electrochemical Science vol 8 pp 1759ndash1769 2013

[35] K K Alaneme Y S Daramola S J Olusegun andA S AfolabildquoCorrosion inhibition and adsorption characteristics of ricehusk extracts on mild steel immersed in 1M H

2SO4 and HClsolutionsrdquo International Journal of Electrochemical Science vol10 no 4 pp 3553ndash3567 2015

[36] M Prabakaran S H Kim Y T Oh V Raj and I M ChungldquoAnticorrosion properties of momilactone a isolated from ricehullsrdquoThe Journal of Industrial and Engineering Chemistry vol45 pp 380ndash386 2017

[37] H Sheng K Xiaoyang and F Chaoyang ldquoRice bran extractionused as pickling inhibitor in hydrogen chloride acidrdquo Journal of

the Chinese Society of Corrosion and Protection vol 29 pp 149ndash153 2009

[38] W Zhang H Gu L Xi Y Zhang Y Hu and T ZhangldquoPreparation of phytic acid and its characteristics as copperinhibitorrdquo Energy Procedia vol 17 pp 1641ndash1647 2012

[39] L Dong L Yuanhua D Yigang and Z Dezhi ldquoCorrosioninhibition of carbon steel in hydrochloric acid solution by ricebran extractsrdquo Anti-Corrosion Methods and Materials vol 58no 4 pp 205ndash210 2011

[40] S D Toliwal and K Jadav ldquoFatty acid triazolcs derived fromneem rice bran and karanja oils as corrosion inhibitors formildsteelrdquo Indian Journal of Chemical Technology vol 16 pp 32ndash372009

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Submit your manuscripts athttpswwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 201

International Journal ofInternational Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal ofInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of