characterizingthedeacidificationadsorptionmodelof...

Research ArticleCharacterizing the Deacidification Adsorption Model ofOrganic Acids and Phenolic Compounds of Noni ExtractUsing Weak Base Ion Exchanger

Haslaniza Hashim Saiful Irwan Zubairi Wan Aida Wan Mustaphaand Mohamad Yusof Maskat

School of Chemical Sciences amp Food Technology Faculty of Science amp Technology Universiti Kebangsaan Malaysia (UKM)43600 Bangi Selangor Malaysia

Correspondence should be addressed to Haslaniza Hashim haslanizaukmedumy

Received 1 February 2018 Accepted 19 April 2018 Published 5 June 2018

Academic Editor Branca Silva

Copyright copy 2018 Haslaniza Hashim et al (is 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 isproperly cited

Although noni (Morinda citrifolia L) has been used to treat a broad range of diseases many people avoid consuming the fruitsbecause of its unpleasant odor caused by organic acids Even though ion exchange resins were able to reduce the odor it alsoreduced beneficial antioxidant compounds (us to preserve antioxidants (phenolic compounds) during deacidification it isimportant to characterize the interaction of ion exchange resin with both organic acids and phenolic compounds Adsorptioncapacities of organic acids and phenolic compounds commonly found in the noni fruit were conducted onto Amberlite IRA 67resin (e phase contact time to reach equilibrium for octanoic acid and hexanoic acid compounds was 32686 and 16072minrespectively (e values of initial adsorption rate 1K1 and adsorption extent 1K2 decreased with the increase of initialconcentration for all compounds studied Results for all the compounds studied fitted well to the Langmuir model (e effect ofpH in adsorption capacity of the actual system (noni juice) has been applied based on the model system studied

1 Introduction

Morinda citrifolia L or noni is one of the traditional folkmedicinal plants that has been used for over 2000 years inPolynesia According to the European Commision [1] it hasbeen accepted in the European Union as a novel foodHowever noni extracts exude a strong unpleasant odor (eunpleasant odor of noni extract contributed bymedium-chainfatty acids such as caproic (hexanoic) and caprylic (octanoic)acid [2] decreases the level of consumersrsquo acceptance

Deacidification is a process that is used to reduce thelevel of acid in food systems Ion exchange and adsorbentresins have shown promising results in the modification ofacids in fruit juice Several studies to deacidify fruit juicesusing ion exchange resin have also been performed onpassion fruit [3] However although the unpleasant odorwas reduced antioxidant activities were also reduced

Haslaniza et al [4] reported that noni juice treated with weakbase anion exchange resin (Amberlite IRA 67) showedpromising potential in reduction of octanoic and hexanoicacids while it also gave minimal reduction on antioxidantcontent Increased attention has been given on the role ofnatural antioxidants in particular phenolic compoundswhich may act both by reducing the content of toxiccompounds in foods and by supplying the human body withexogenous antioxidants [5] Due to the beneficial role ofantioxidants it is important that deacidification did notreduce the antioxidant activity in the noni juice

To characterize the adsorption process Pelegrsquos modelcan be used to determine the equilibrium phase contact timeand maximum adsorption yield throughout the process Asreported by previous researchers the model has been used todescribe sorption processes in various food systems [6ndash8]Poojary and Passamonti [9] also applied this model to

HindawiJournal of ChemistryVolume 2018 Article ID 6376929 10 pageshttpsdoiorg10115520186376929

predict the kinetics and modelling in the extraction of ly-copene in tomato waste using organic solvents Pelegrsquosmodel adequately describes the rate of the adsorptionprocess adsorption extent and exhaustive time of thecompounds studied Meanwhile the Langmuir andFreundlich models can be used to predict the adsorptionisotherm for the compounds studied

In order to reduce the unpleasant odor of noni juice butat the same time conserve the antioxidants during the de-acidification process it is important to understand the in-teraction of both unpleasant odor compounds of organicacids and antioxidants with ion exchange resins (us thisstudy was carried out to determine the adsorption charac-teristics between organic acids (octanoic acid and hexanoicacid) and phenolic compounds (rutin scopoletin andquercetin) onto a weakly basic ion exchange resin usinga model system

2 Materials and Methods

21 Materials Weak base anion exchanger Amberlite IRA67 and standards of octanoic acid hexanoic acid rutinscopoletin and quercetin were purchased from Sigma-Aldrich Corporation (St Louis MO USA) AmberliteIRA 67 was used due to its higher performance for theadsorption of some organic acid compounds as reported byHaslaniza et al [4] Rutin scopoletin and quercetin wereused due to its existence in all noni fruits and commercialnoni juices from different countries all over the world al-though at different ranges of concentration [10] Methanol(HPLC grade purity gt999) was purchased from FisherScientific (New Jersey USA)

22 Adsorption Studies of Organic Acids and PhenolicCompounds (e adsorption studies of organic acids andphenolic compounds onto weakly basic ion exchanger resinwere carried out in Erlenmeyer flasks where 01 g of the dryanion exchanger and 002 L of each sample which wereoctanoic acid (250 500 750 and 1000mgL) hexanoic acid(100 200 300 and 400mgL) rutin (25 50 75 and100mgL) scopoletin (25 50 75 and 100mgL) andquercetin (25 50 75 and 100mgL) were added without pHadjustment (e flasks were agitated in an orbital shaker(WiseCube Daihan Scientific Korea) at a constant speed of120 rpm for 180min at room temperature (25degC) to achieveequilibrium [11] Each of the organic acid after equilibriumwas measured using a gas chromatographer (Agilent ModelHP6890 USA) equipped with a flame ion detector (FID)Each of the phenolic compounds was measured using high-performance liquid chromatography (HPLC) (e amountof organic acids and phenolic compounds adsorbed atequilibrium qe (mgg) were calculated using the followingequation

qe Co minusCe

wtimes V (1)

where Co and Ce were the concentrations (mgL) of eachorganic acid and phenolic compound at the beginning

and after equilibrium respectively V was the volume ofthe solution (L) and w was the mass of the dry anionexchanger (g)

23 Kinetics of Liquid-Liquid Adsorption (e Peleg modelhas been used to describe adsorption processes in variousfoods [12ndash14] (e adsorption curves (concentration of eachorganic acidphenolic compound versus time) could bedescribed by a model proposed by Peleg [15] which in case ofadsorption would assume the form as stated below

C(t) Co +t

K1 + K2 middot t (2)

where C(t) is the concentration of each organicacidphenolic compound at time t (mgg) t is the adsorptiontime (min) Co is the initial concentration of each organicacidphenolic compound at time t 0 (mgg) K1 is Pelegrsquosrate constant (minmiddotgmg) and K2 is Pelegrsquos capacity constant(gmg) Equation (2) was used in the final form while Co 0in all experiments

C(t) t


K1 is Pelegrsquos rate constant which is related to adsorptionrate (B0) at the very beginning (t t0)

B0 1

K1

mgg

middot min1113888 1113889 (4)

K2 is Pelegrsquos capacity constant which is related tomaximum adsorption yield or equilibrium concentration ofadsorbed compounds (Ce) When trarrinfin

C(trarrinfin) Ce 1

K2

mgg

1113888 1113889 (5)

24Determination ofOrganicAcids Organic acids (octanoicacid and hexanoic acid) were extracted using Gas Chro-matography Solid Phase Microextraction (GC-SPME) (eSPME inlet used was 075mm (Supelco) SPME needlecontained divinylbenzene-carboxen-polydimethylsiloxane(DVB-CAR-PDMS) fiber (StableFlex Supelco) (e sam-ple (1mL) was added into a headspace vial sealed withsilicone septum and layered with Teflon-faced silicone septa(Supelco USA) (en it was heated in a waterbath(Memmert Germany) at 53degC for 12min [16] After heatingSPME needle was directly injected through the septum intothe vial for 10min After extraction the needle was removedfrom the vial and injected to the gas chromatographer

Gas chromatography was performed using a gas chro-matographer mass spectrometry (Agilent Model HP6890USA) equipped with a flame ion detector (FID) and splitlessinjector Separation of the organic compounds was doneusing a capillary column HP-5 (30mtimes 025 id 025 μm filmthickness JampW Scientific Pte Ltd USA) Oven temperaturewas programmed according to the method of Zamboninet al [17] with the following parameters initial temperaturewas 50degC for 2min before it raised to 80degC at 20degCmin for

2 Journal of Chemistry

1min and then heated to 100degC at 20degCmin for 1minWhenit reached 100degC the temperature finally rose to 250degC at30degCmin and was held for 2min (e gas flow rate wasmaintained at 40 cm3s with nitrogen (N2) used as carriergas (e total separation time for each samples were135min Volatile compounds were identified by comparingthe peak retention time to those of pure standard with thepeak retention time for deacidified samples(e analysis wasexpressed as concentration (mgL) obtained from thesoftware

25Determinationof PhenolicCompounds Determination ofphenolic compounds was carried out using high-performanceliquid chromatography (HPLC) as reported byHaslaniza et al[4] (e standards (scopoletin rutin and quercetin) wereweighed and dissolved in appropriate volume of methanolicsolution using deionized water to produce stock standardsolutions To construct calibration curves for each standardthe working standard was prepared by diluting stock standardsolutions with methanolic solution at different concentra-tions Before injected into HPLC instrumentation sampleswere filtered through a 022 μm membrane filter (IwakiGlass)

(e determination of selected phenolic compounds wasdetermined by the modified Analytical HPLC Application031481 Merck USA (2008) method for an HPLC systemBriefly the samplesstandard solutions (20 μL) were in-jected into a Shimadzu chromatographer 20A coupled withphotodiode array detector (PDA) equipped with Chro-molith Performance RP-18 endcapped Merck UK (Catnumber 102129) (e pump was connected to two mobilephases A methanoldeionized water (25 975 vv) and Bmethanoldeionized water (50 50 vv) (e elution flowrate was 21mLmin at 25min with a column temperaturemaintained at 30degC (e mobile phase was set as a lineargradient as it afforded a good separation and symmetricalpeak shape of target analytes in the chromatograms (enit was programmed as follows 0ndash10min 100 A 0 B10ndash15min 65 A 35 B 15ndash20min 0 A 100 B20ndash22min 100 A 0 B and 22ndash25min 100 A 0 B(e PDA spectra was monitored in the range of 210 to450 nm and quantified at 365 nm Data analyses were doneusing Shimadzu Lab Solution software

26Adsorption Isotherm (e adsorption isotherm indicatedhow the adsorption molecules distribute between the liquidphase and the solid phase when the equilibrium state wasreached [18] (e data of the adsorption process for theorganic acids and three phenolic compounds were analyzedusing the Langmuir isotherm linear model according to thefollowing equation [19]

Ce

qe

1qm

Ce +1

KLqm (6)

where qe is the adsorption capacity of each compound atequilibrium (mgg) Ce is the equilibrium concentration ofeach compound (mgL) KL is a Langmuir adsorptionconstant which is related to the affinity of the adsorption

(Lmg) and qm is a maximum capacity or the amount oforganic acids adsorbed at complete monolayer coverage(mgg) (e values of KL and qm are obtained from theintercept and slope respectively of the straight line plot ofCeqe versus Ce Another model Freundlich adsorptionisotherm and its linearized form are given in the followingequations [18]

qe KF + C1ne (7)

log qe log KF +1nlog Ce (8)

whereKF and 1n are the Freundlich equilibrium coefficientsrelated to the adsorption capacity and adsorption intensityrespectively [20] A plot of log qe versus log Ce givesa straight line with a slope (1n) and an intercept at log KF

(e favorability of the sorption system in the batchprocess was estimated from the shape of the isotherm whichmay be indicated by essential characteristics of the Langmuirisotherm expressed in terms of a dimensionless constantseparation factor RL given by the following equation [21]

RL 1

1 + KLCo (9)

where KL is the Langmuir constant (Lmg) and Co is theinitial organic acid concentration (mgL) (e value of RLindicates whether the isotherm is unfavourable (RL gt 1)linear (RL 1) favourable (0ltRL lt 1) or irreversible(RL 0) [22 23]

27 StatisticalMethods Data were analyzed using StatisticalAnalytical System (SAS) version 913 for T-test All ex-periments were done using three replications (e param-eters of modified Pelegrsquos model (constants K1 and K2) weredetermined from experimental data Validation between theexperimental data and predicted value was established byroot mean squared deviation (RMSD) as described byPineiro et al [24] using the following equation

RMSD

1n

1113944(experimentalminus predicted)2

1113970

(10)

3 Results and Discussion

31 Adsorption Capacity and Exhaustive Time Characteristicsas Influenced by Initial Concentration (e influence ofdifferent concentrations of octanoic and hexanoic acids onadsorption capacity at 303K and 120 rpm agitation speedcan be seen in Figure 1 (e concentrations of adsorbedcompounds were calculated according to (1)(e adsorptioncurves indicate the exponential adsorption rate for allconcentration ranges studied

From Figure 1 the plot reveals rapid uptake at the initialstages followed by a gradual increase as equilibrium wasreached (e adsorption capacity was higher initially due togreater availability of vacant sites for adsorption Aftera period of time the number of vacant sites became less andeventually all available sites became saturated [25] As

Journal of Chemistry 3

mentioned by Amin [26] and Kannan and Sundaram [27]the rate of organic acids removal was controlled by the rateof organic acids transported to the exterior sites of theadsorbent until all available surface sites were fully occupiedafter the initial adsorption As other variables such as resinmass temperature and agitation speed were the same fordierent experimental runs the organic acids concentrationaected the diusion of organic acids molecules through thesolution to the surface of the Amberlite IRA 67 Higherconcentration resulted in a higher driving force of theconcentration gradient [22] is driving force acceleratedthe diusion of organic acids from the solution onto theadsorbent [28] is phenomenon of adsorption is welldescribed by Pelegrsquos model [15] e experimental adsorp-tion extent calculated parameters of modied Pelegrsquos model(constants K1 and K2) regression coecient (R2) andRMSD are shown in Tables 1 and 2e R2 was high for bothoctanoic and hexanoic acids (R2gt 075) with the p values lessthan 005 which showed adequate presentation of the ex-perimental and data by Pelegrsquos model

e initial adsorption rate and the maximum adsorptionextent in experimental conditions were calculated fromconstantK1 andK2 using (4) and (5)K1 decreased as initialconcentrations of both octanoic acid and hexanoic acidincreased indicating increased adsorption rates with in-creasing initial concentration of octanoic acid and hexanoicacid K2 is a constant inversely related to maximum ad-sorption capacity WhenK2 is lower the adsorption capacityis higher [12] K2 for octanoic acid and hexanoic acid de-creased linearly with increasing concentration as presentedin Tables 1 and 2 When the octanoic acid and hexanoic acidconcentrations did not vary with the phase contact time theadsorption equilibrium is accomplished According to dataobtained from the Peleg model extrapolation (data notshown) equilibrium time was found to be 32686min foroctanoic acid and 16072min for hexanoic acid which werestatistically dierent (plt 005)

Figure 2 displays the inuence of dierent concentra-tions of rutin scopoletin and quercetin on adsorption ca-pacity at 303K and 120 rpm agitation speed e three

20 40 60 80 100 120 140 160 180Phase contact time t (min)

0

20

40

60

80

100

120

Adso

rptio

n ca

paci

ty q

(mg

g)

250 mgL500 mgL

750 mgL1000 mgL

(a)

0

10

20

30

40

50

Adso

rptio

n ca

paci

ty q

(mg

g)

40 60 80 100 120 140 160 18020Phase contact time t (min)

100 mgL200 mgL

300 mgL400 mgL

(b)

Figure 1 Kinetic of (a) octanoic acid and (b) hexanoic acid adsorption onto a weak base ion exchange resin (Amberlite IRA 67) at dierentorganic acid concentrations Graph represents the mean of three replicate samples with error bars

Table 1 Values of adsorption extent Pelegrsquos constants (K1 andK2) for adsorption of octanoic acid with regression coecient (R2) and theroot mean squared deviation (RMSD) at dierent initial concentrations

Initial concentration(mgL)

Adsorption extent(mgg)

K1(minmiddotgmg) K2 (gmg) R2 RMSD

(adsorption extent)Exhaustivetime (Peleg)

RMSD(exhaustive time)

250 3704plusmn 226 1086plusmn 0082 0027plusmn 0004 0920 079 31309plusmn 417 551500 4167plusmn 220 0497plusmn 0025 0024plusmn 0000 0966 063 32601plusmn 412 465750 7143plusmn 346 0132plusmn 0068 0014plusmn 0005 0993 016 33085plusmn 353 2331000 11111plusmn 469 0196plusmn 0041 0009plusmn 0001 0942 077 33747plusmn 480 266

Table 2 Values of adsorption extent Pelegrsquos constants (K1 andK2) for adsorption of hexanoic acid with regression coecient (R2) and theroot mean squared deviation (RMSD) at dierent initial concentrations








curves show the exponential increase of adsorption rate foreach individual antioxidant at given contact time (180min)for four dierent initial concentrations from 25 to 100mgLAs can be seen in Figure 2 the three curves gave similaradsorption proles Similar to organic acids the adsorptioncapacities of phenolic compounds increased as time in-creased due to the higher amount of phenolic compoundsadsorbed onto the weakly basic anion exchanger Aftera certain period of time the adsorption rate decreased as itreached the equilibrium point e equilibrium point wasreached when all of the antioxidant compounds adsorbedto the resin (at lower antioxidant concentration) or the vacantsites of Amberlite IRA 67 were fully occupied (at higherantioxidant concentration) e decreased adsorption rateafter equilibriummight happen due to the physical adsorption(physisorption) of the phenolic compounds and AmberliteIRA 67 In physical adsorption the weak van der Waalsforces act It involves the weak force attraction between theadsorbate and adsorbent and therefore this type of ad-sorption can be easily reversed Similar phenomenon hap-pened in this study where the phenolic compounds are notxed to the Amberlite IRA 67 and canmove freely within theinterfacial surfaces [29]

According to Pelegrsquos value for the individual antioxi-dant compounds as shown in Tables 3ndash5 K1 values

decreased suggesting a corresponding increase in the initialadsorption rates of the phenolic compounds with in-creasing concentration Zin et al [5] and Hasnain et al [22]reported that most phenolic compounds found in the nonifruit are nonpolar in nature including the phenolic com-pounds studied High porosity and hydrophobic nature ofresins has been reported to allow the adsorption of non-polar phenolic compounds through hydrophobic in-teractions [30] and van der Waals forces [31] us it ishighly probable that dierent from organic acids ad-sorption of antioxidant compounds from noni juice is alsodue to the hydrophobic interactioneK2 values for rutinscopoletin and quercetin also decreased as concentrationincreased e adsorption extent was inuenced by theinitial concentration of phenolic compounds R2 for thesethree phenolic compounds were acceptable (R2gt 075) eRMSD had relatively a low value for the compounds

Increasing adsorption rate namely decreasing K1 withincreasing initial concentration is expected adsorption be-haviour e same phenomenon happened in water ab-sorption in chickpea during soaking [12] Table 6 showstting of Pelegrsquos rate constant and K1 for organic acids andphenolic compounds at dierent initial concentrations Asdiscussed earlier K1 decreased as initial concentration oforganic acids and antioxidants increased As summarized in

0

1

1

2

2

3Ad

sorp

tion

capa

city

q (m

gg)


25 mgL50 mgL

75 mgL100 mgL

(a)

0

1

1

2

2

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(b)

0

1

1

2

2

3

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(c)

Figure 2 Kinetic of (a) rutin (b) scopoletin and (c) quercetin adsorption onto a weak-base ion exchange resin (Amberlite IRA 67) atdierent phenolic compound concentrations Graph represents the mean of three replicate samples with error bars


Table 6 octanoic acid hexanoic acid and scopoletin fittedthe linear regression model while rutin and quercetin fittedthe nonlinear regression model It can be clearly observedthat the rate of adsorption with increasing concentration forthe antioxidant compounds were higher compared to theorganic acids (is further explained the reduction of an-tioxidant activity during deacidification

K2 is a constant related to adsorption capacity(e lowerthe K2 the higher the adsorption capacity [12] Table 8shows fitting of Pelegrsquos capacity constant and K2 for organicacids and phenolic compounds at different initial concen-trations According to Table 7 octanoic acid hexanoic acidand scopoletin fitted the linear regression model while rutinand quercetin fitted the nonlinear regression model similarto the trend in K1 However based on the R2 value data forscopoletin were not adequately represented by the model(e p values for scopoletin also were slightly higher than005 indicated that the compound was not significantSimilar to K1 rate of increase for K2 of rutin and quercetinwas higher than octanoic and hexanoic acids

32 Equilibrium Isotherm (e Langmuir isotherm modelhas been used to describe the adsorption isotherm ofcompounds studied (organic acids and phenolic com-pounds) which involved the relation between adsorptioncapacity and solution concentration as mentioned byParsaei and Goodarzi [32] (e adsorption isotherm in-dicated how the adsorption molecules distribute betweenthe liquid phase and the solid phase when the equilibrium

state was reached [18] (e Langmuir isotherm modelassumes that intermolecular forces between adsorbingmolecules are negligible and that once available sites onadsorbent are fully occupied no further adsorption takesplace [25] Meanwhile the Freundlich isotherm describes

Table 3 Values of adsorption extent Pelegrsquos constants (K1 and K2) for adsorption of rutin with regression coefficient (R2) and the rootmean squared deviation (RMSD) at different initial concentrations


Adsorptionextent (mgg)

K1(minmiddotgmg)

K2(gmg) R2 RMSD




Table 4 Values of adsorption extent Pelegrsquos constants (K1 andK2) for adsorption of scopoletin with regression coefficient (R2) and the rootmean squared deviation (RMSD) at different initial concentrations



K1(minmiddotgmg)

K2(gmg) R2 RMSD




Table 5 Values of adsorption extent Pelegrsquos constants (K1 and K2) for adsorption of quercetin with regression coefficient (R2) and the rootmean squared deviation (RMSD) at different initial concentrations



K1(minmiddotgmg)

K2(gmg) R2 RMSD




Table 6 Equation and regression coefficient of Pelegrsquos rate con-stant for organic acids (octanoic acid and hexanoic acid) andphenolic compounds (scopoletin quercetin and rutin) at differentinitial concentrations

Compound Equation Regression coefficient R2

Octanoic acid yminus0001x+ 1236 0809Hexanoic acid yminus0012x+ 5965 0848

Rutin yminus138 ln(x) + 7644 0616

Scopoletin yminus0555x+ 7175 0953

Quercetin yminus207 ln(x) + 1058 0692

Table 7 Equation and regression coefficient of Pelegrsquos capacityconstant for organic acids (octanoic acid and hexanoic acid) andphenolic compounds (scopoletin quercetin and rutin) at differentinitial concentrations


Octanoic acid yminus3Eminus 05x+ 0034 0961Hexanoic acid yminus0000x+ 0247 0775





heterogeneous systems and reversible adsorption and isnot limited to the formation of a complete monolayer [22]

33 Organic Acids For organic acids (octanoic and hex-anoic acids) the adsorption data were applied to bothlinearized form of Langmuir and Freundlich equationsAccording to Table 8 for octanoic acid the values of R2086 for Langmuir and 099 for Freundlich suggest thatboth homogeneous and heterogeneous monolayer mecha-nism in the adsorption process were at play (e values of theLangmuir dimensionless separation factor RL lie between0 and 1 (Table 9) Hence the sorption system may be con-sidered favourable by the Langmuir model Similar to the RLvalue from the Langmuir isotherm the n value from theFreundlich isotherm is related to the adsorption intensitywhere ngt 1 indicates good adsorption over different equi-librium concentrations [33 34] If n valuelt 1 adsorptionintensity is only good at high concentration [34] As shown inTable 8 the n value found to be 08244 for octanoic acidadsorption by Amberlite IRA 67 suggested that it is moresuitable at high concentration only(emaximummonolayercapacities qm for sorption of octanoic acid were 25000mgg

Table 8 also shows the Langmuir and Freundlich iso-therm models of hexanoic acid sorption on Amberlite IRA67 (e values of R2 were found to be 078 for Langmuir and092 for Freundlich (e value of the Langmuir di-mensionless separation factor RL for hexanoic acid wasbetween 0 and 1 indicating that the sorption process isfavourable for this adsorbent [25] (e n value of 0346 fromthe Freundlich isotherm also indicates that hexanoic acidadsorption which is only suitable at high concentration (emaximummonolayer capacities qm for sorption of hexanoicacid were 719mgg For both organic acids studied theobserved data (Table 9) show that RL values decrease withincreasing concentration suggesting that the organic acidsuptake process is more favourable with higher concentrationof organic acids as reported by [35] in the biosorption ofmetal dyes onto Agave americana (L) fibres

34 PhenolicCompounds (e data of adsorption process forthe three phenolic compounds (rutin scopoletin andquercetin) were analyzed using the Langmuir isothermlinear model (e linearized form of the Langmuir isothermof each phenolic compound on Amberlite IRA 67 resin wasfound to be linear over the whole concentration rangestudied and the correlation coefficients were high (gt08)while the correlation coefficients for the Freundlich isothermwere low (lt03) (e high degree of correlation for the

linearized Langmuir relationship suggested that a singlesurface reaction with constant activation energy was thepredominant rate-controlling step [36]

As observed in Table 8 the results shows that the ad-sorption capacity (qm) of rutin scopoletin and quercetinwas found to be 270 180 and 222mgg respectively usingthe linearized Langmuir isotherm model (e adsorptionmechanism seems to obey the homogeneous monolayermodel better than the heterogeneous model (e favorabilityof the adsorption process for the phenolic compounds isreflected by the Langmuir dimensionless separation factor(0ltRL lt 1) [25] as shown in Table 9 Similar to organicacids the RL values decrease with increasing initial con-centration suggesting that the phenolic compounds uptakeprocess is more favourable at higher concentration (egood correlation coefficients and the values of RL confirmedthat the Langmuir isotherm is a suitable isotherm for ad-sorption of each phenolic compound onto Amberlite IRA 67resin compared to the Freundlich isotherm

Adsorption capacity (qm) of all phenolic compounds waslower than both organic acids showing lower adsorptioncapacities However all three phenolic compounds showedhigher KL values than both organic acids (is suggest thatthe phenolic compounds have higher adsorption affinitytowards organic acids which may contribute to the higher

Table 8 Langmuir and Freundlich isotherm constants and correlation coefficients for octanoic acid adsorption by Amberlite IRA 67

CompoundLangmuir isotherm coefficients Freundlich isotherm coefficients

Equation qm (mgg) KL (Lmg) R2 Equation n (mgg) KF (Lmg) R2

Octanoic acid yminus0004x+ 734 25000 545times10minus4 086 y 1213xminus 1286 08244 028 099Hexanoic acid yminus0139x+ 2665 719 522times10minus3 078 y 2890xminus 4805 0346 00082 092Rutin y 0371xminus 0583 270 06364 081 y 0308xminus 0057 3247 1059 028Scopoletin yminus0556xminus 4207 180 01322 094 y 0013x+ 0318 7692 1374 000Quercetin yminus0451xminus 2849 222 01583 094 yminus0022x+ 0456 4545 1578 002

Table 9 RL values for Amberlite IRA 67 on the adsorption oforganic acids and phenolic compounds

Compound Initial concentration Co (mgL) RL

Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350


rate of Pelegrsquos K1 constant as shown in Table 6 e resultsindicate that in its present characteristics it would bedicult to reduce the adsorption of phenolic compounds

35 Actual System pH plays an important role in the ad-sorption process particularly on the adsorption capacity[22] In order to determine the actual interaction of studiedcompounds the inuence of pH on adsorption of organicacids (octanoic and hexanoic acid) and phenolic compounds(rutin scopoletin and quercetin) has been applied in nonijuice based on the model system

e eect of pH in the solution on the adsorption capacityqe (mgg) of organic acids in noni juice on Amberlite IRA 67was studied at a pH range of 2ndash11 as shown in Figure 3 eexperiment was performed with initial octanoic and hexanoicacid concentrations of 24903 and 10421mgL respectively at303K with a contact time of 327min As can be seen inFigure 3 there was a similar trend in adsorption capacity ofboth organic acids onto weak base ion exchange resinAmberlite IRA 67 Control samples A (noni juice withoutresin and agitation) and B (noni juice without resin withagitation) show no signicant dierence for both organicacids Agitation rate and time did not inuence much to theconcentration of organic acids However adsorption ca-pacity of organic acids in noni juice is signicantly(plt 005) increased when treated at dierent pH comparedto control samples For both organic acids noni juicetreated at pH 2 showed the lowest (plt 005) adsorptioncapacity As the pH increased adsorption capacity alsoincreases up to pH 5 No signicant dierence was observedbetween samples of pH 5 to 11 It explained that themaximum removal of organic acids (octanoic and hexanoicacid) by Amberlite IRA 67 was achieved at pH 4

From the observation adsorption capacity of organicacids increases with increasing pH values It might be due tothe rate of protonation of the compounds in aqueous solutionAs reported by Berbar et al [37] during the adsorption of

polyethyleneimine using anion exchange resin adsorption ismore favoured at low acidic solution but not at strong acidiccondition It happened due to the reduction of the positiverepulsive interactions between functional groups at high pHis explained the eect of pH of solution on the adsorptionof organic acids (octanoic and hexanoic acids) onto resinsurface

Figure 4 indicates the eect of pH on the adsorptioncapacity qe (mgg) of phenolic compounds (scopoletinrutin and quercetin) in noni juice using Amberlite IRA 67 ata pH range of 2ndash11 e experiment was conducted withinitial scopoletin rutin and quercetin concentration of 52348623 and 1246mgL respectively at 303K with a contact

d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a

e e d c c c c c b a a a

020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values

ScopoletinRutinQuercetin

Figure 4 Eect of pH of phenolic compounds (scopoletin rutinand quercetin) adsorption in noni juice onto a weak base ionexchange resin (Amberlite IRA 67) at dierent pH Graph rep-resents the mean of three replicate samples with error barslowastDierent letters in the same phenolic compounds indicate sig-nicant dierence (plt 005)

d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)

FIGURE 3 Eect of pH of (a) octanoic acid and (b) hexanoic acid adsorption in noni juice onto a weak base ion exchange resin (AmberliteIRA 67) at dierent pH Graph represents the mean of three replicate samples with error bar Dierent letters on the bars indicatesignicant dierences (plt 005)


time of 327min As expected no significant difference wasobserved in control samples A (noni juice without resin andagitation) and B (noni juice without resin and with agitation)It means that agitation time and rate also did not affect boththe control samples According to Figure 4 adsorption ca-pacity of these three phenolic compounds in noni juice waslow at highly acidic medium and gradually increased withincreasing pH values up to pH 11 except quercetin (ehighest (plt 005) adsorption capacity of scopoletin was foundat pH 5 and remained constant until pH 11 whereas thehighest (plt 005) adsorption capacity of rutin was reached atpH 6 (ere was no significant difference observed betweenpH 6 and 11 However quercetin gave the highest (plt 005)adsorption capacity at pH 9 to 11

Although there was a similar trend of adsorption ca-pacity for these three phenolic compounds the pH wheremaximum adsorption capacity achieved was different fromeach of them According to Altiok et al [38] the resultsmight be different from other phenolic compounds asphenolic profile varies in their molecular sizes and formswhich influence their solubility and adsorption As the valueof pH increase adsorption capacities of phenolic com-pounds also increase It might happen due to the decrease incompetition between the charged ions for the same func-tional group of the resin used A change of the H3O+

concentration in the solution resulted changes in the ratio ofprotonatedunprotonated polyphenolic compounds Pro-tonation of these polyphenolic compounds significantlychange their charges as well as the affinity to negativelycharged adsorption resin Amberlite IRA 67 [39]

Based on the results noni juice treated with weak baseanion exchange resin (Amberlite IRA 67) showed prom-ising potential in octanoic and hexanoic acid removal whileit also minimize the loss of antioxidants at specific pHHaslaniza et al [4 11] also reported that noni juice treatedwith the same resin is good to be used for deodorizationdue to lower reduction on antioxidant content compared toother resins

4 Conclusion

Based on the model system it shows adsorption ontoAmberlite IRA 67 was influenced by the initial concentrationof each compound (e removal of both organic acids andphenolic compounds was shown to be dependent on phasecontact time and initial concentration (e initial concen-tration influences the adsorption kinetics of each compoundstudied Also the values of initial adsorption rate 1K1 andadsorption extent 1K2 decreased with the increase of initialconcentration for both organic acids and phenolic com-pounds As for the isotherm model the results for all thecompounds studied fitted well to the Langmuir model asa monolayer sorption (e Langmuir model suggestsa higher adsorption affinity of the phenolic compoundscompared to both organic acids Based on the adsorptioncharacteristics no differences were observed that coulddifferentiate the adsorption between organic acids andphenolic compounds (us further studies are needed tobe able to differentiate and subsequently maximize organic

acids adsorption while minimizing phenolic compoundsreduction Based on the results noni juice treated withweak base anion exchange resin (Amberlite IRA 67)showed promising potential in octanoic and hexanoic acidremoval while it also minimizes the loss of antioxidants atspecific pH

Data Availability

(e data used to support the findings of this study areavailable from the corresponding author upon request

Conflicts of Interest

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

Acknowledgments

(e authors would like to thank the Ministry of Education(MOE) for the scholarship Ministry of Science Technologyand Innovation (MOSTI) for financing the project underGrant ERGS12013STWN03UKM021 and UniversitiKebangsaan Malaysia Bangi Selangor Malaysia

References

[1] European Commission Scientific Committee of FoodOpinion of the Scientific Committee on Food of Tahitian NonisJuice SCFCSDOS18 ADD 2 European CommissionBrussels Belgium 2002

[2] H Norma A Normah A W Ahmad M Y RohaniM Muhammad Gawas and A Sharizan ldquoReducing the smellycompounds (caproic caprylic and capric acids) in noni bytreating the juice with activated charcoal powderrdquo in Pro-ceedings of the National Food Technology Seminar Malaysia2004

[3] E Vera M Dornier J Ruales F Vaillant and M ReynesldquoComparison between different ion exchange resins for thedeacidification of passion fruit juicerdquo Journal of Food Engi-neering vol 57 no 2 pp 89ndash96 2003

[4] H Haslaniza W A Wan Yaacob H Osman andM Y Maskat ldquoInteraction of antioxidants and organic acidfrom noni (Morinda citrifolia L) juice with ion exchangeresins during deodorization via deacidificationrdquo Der PharmaChemica vol 7 no 9 pp 9ndash21 2015

[5] Z M Zin A A Hamid A Osman and N Saari ldquoAnti-oxidative activities of chromatographic fractions obtainedfrom root fruit and leaf of Mengkudu (Morinda citrifolia L)rdquoFood Chemistry vol 94 no 2 pp 169ndash178 2006

[6] VMaharaj and C K Sankat ldquoRehydration characteristics andquality of dehydrated dasheen leavesrdquo Canadian AgriculturalEngineering vol 42 pp 81ndash85 2000

[7] P A Sopade and K Kaimur ldquoApplication of Pelegrsquos equationin desorption studies of food systems a case study with sago(Metroxylon Sagu rottb) starchrdquo Drying Technology vol 17no 4-5 pp 975ndash989 1999

[8] E Palou A Lopez-Malo A Argaiz and J Welti ldquoUse ofPelegrsquos equation to osmotic concentration of papayardquo DryingTechnology vol 12 no 4 pp 965ndash978 1994

[9] M M Poojary and P Passamonti ldquoExtraction of lycopenefrom tomato processing waste kinetics and modellingrdquo FoodChemistry vol 173 pp 943ndash950 2015


[10] S Deng B J West and C J Jensen ldquoA quantitative com-parison of phytochemical components in global noni fruitsand their commercial productsrdquo Food Chemistry vol 122no 1 pp 267ndash270 2010

[11] H Haslaniza W A Wan Yaacob S I Zubairi andM Y Maskat ldquoPotential of Amberlite IRA 67 resin for de-acidification of organic acids in noni juicerdquo Der PharmaChemica vol 7 no 12 pp 62ndash69 2015

[12] M Turhan S Sayar and S Gunasekaran ldquoApplication ofPeleg model to study water absorption in chickpea duringsoakingrdquo Journal of Food Engineering vol 53 no 2pp 153ndash159 2002

[13] F N M Fazil N S M Azzimia B H YahayaN A Kamalaldin and S I Zubairi ldquoKinetics extractionmodelling and antiproliferative activity of Clinacanthusnutans water extractrdquo lte Scientific World Journal vol 2016Article ID 7370536 7 pages 2016

[14] Z S Othman N S Hasan and S I Zubairi ldquoResponse surfaceoptimization of rotenone using natural alcohol-based deepeutectic solvent as additive in the extraction medium cock-tailrdquo Journal of Chemistry vol 2017 Article ID 9434168 10pages 2017

[15] M Peleg ldquoAn empirical model for the description of moisturesorption curvesrdquo Journal of Food Sciences vol 53 no 4pp 1216ndash1219 1988

[16] Y Noor Hafizah Kesan Penyahasidan Terhadap Ciri-CiriEkstrak Mengkudu (Morinda citrifolia L) MS thesis Uni-versiti Kebangsaan Malaysia Bangi Selangor Malaysia 2011

[17] C G Zambonin M Quinto N De Vietro and F PalmisanoldquoSolid-phase microextractionndashgas chromatography massspectrometry a fast and simple screening method for theassessment of organophosphorus pesticides residues in wineand fruit juicesrdquo Food Chemistry vol 86 no 2 pp 269ndash2742004

[18] M Wawrzkiewicz and Z Hubicki ldquoEquilibrium and kineticstudies on the adsorption of acidic dye by the gel anion ex-changerrdquo Journal of Hazardous Materials vol 172 no 2-3pp 868ndash874 2009

[19] H Yuh-Shan ldquoIsotherms for the sorption of lead onto peatcomparison of linear and non-linear methodsrdquo Polish Journalof Environmental Studies vol 15 no 1 pp 81ndash86 2006

[20] A Mittal D Kaur and J Mittal ldquoBatch and bulk removal ofa triarylmethane dye Fast Green FCF from wastewater byadsorption over waste materialsrdquo Journal of HazardousMaterials vol 163 no 2-3 pp 568ndash577 2009

[21] R L Johnson and B V Chandler ldquoReduction of bitternessand acidity in grape fruit juice by adsorption processesrdquoJournal of Science and Food Agricultural vol 33 no 3pp 287ndash293 1982

[22] M Hasnain Isa L S Lang F A H Asaari H A AzizN Azam Ramli and J P A Dhas ldquoLow cost removal ofdisperse dyes from aqueous solution using palm ashrdquo Dyesand Pigments vol 74 pp 446ndash453 2007

[23] Y S Yien O Hassan and S I Zubairi ldquoDeodorizingmechanism of β-cyclodextrin-organic acids inclusion againststrong odor of Morinda Citrifolia (Mengkudu) juicerdquo JurnalTeknologi vol 79 no 10 pp 67ndash75 2016

[24] G Pineiro S Perelman J P Guerschman and J M ParueloldquoHow to evaluate models observed vs predicted or predictedvs observedrdquo Ecological Modelling vol 216 no 3-4pp 316ndash322 2008

[25] S S Mariam Y Yamin and H Zaini ldquoAdsorption of anionicamido black dye by layered double hydroxide ZnAlCO3-

LDHrdquo lte Malaysian Journal of Analytical Sciences vol 13no 1 pp 120ndash128 2009

[26] N K Amin ldquoRemoval of reactive dye from aqueous solutionsby adsorption onto activated carbons prepared from sugar-cane bagasse pithrdquo Desalination vol 223 no 1ndash3pp 152ndash161 2008

[27] N Kannan andMM Sundaram ldquoKinetics andmechanism ofremoval of methylene blue by adsorption on various carbons-a comparative studyrdquo Dyes and Pigments vol 51 no 1pp 25ndash40 2001

[28] M Ozacar and A I Sengil ldquoAdsorption of metal complexdyes from aqueous solutions by pine sawdustrdquo BioresourceTechnology vol 96 no 7 pp 791ndash795 2005

[29] K J Gauraj J A Farhan and K K Rooplteory and Practiceof Physical Pharmacy Elsevier Haryana India 2012

[30] M Carmona A Lucas J Valverde B Velasco andJ Rodriguez ldquoCombined adsorption and ion exchangeequilibrium of phenol on Amberlite IRA-420rdquo ChemicalEngineering Journal vol 117 no 2 pp 155ndash160 2006

[31] X Geng P Ren G Pi R Shi Z Yuan and C Wang ldquoHighselective purification of flavonoids from natural plants basedon polymeric adsorbent with hydrogen-bonding interactionrdquoJournal of Chromatography A vol 1216 no 47 pp 8331ndash83382009

[32] M Parsaei andM S Goodarzi ldquoAdsorption study for removalof boron using ion exchange resin in batch systemrdquo In-ternational Conference on Environmental Sciences and Tech-nology IPCBEE vol 6 pp 398ndash402 Singapore February 2011

[33] O S Amuda and A O Ibrahim ldquoIndustrial wastewatertreatment using natural material as adsorbentrdquo AfricanJournal of Biotechnology vol 5 no 16 pp 1483ndash1487 2006

[34] S Ghorai and K K Pant ldquoInvestigations on the columnperformance of fluoride adsorption by activated alumina ina fixed-bedrdquo Chemical Engineering Journal vol 98 no 1-2pp 165ndash173 2004

[35] A M B Hamissa M C Ncibi B Mahjoub and M SeffenldquoBiosorption of metal dye from aqueous solution onto AgaveAmericana (L) fibresrdquo International Journal of Environ-mental Science and Technology vol 5 no 4 pp 501ndash508 2008

[36] M Greluk and Z Hubicki ldquoComparison of the gel anionexchangers for removal of acid orange 7 from aqueous so-lutionrdquo Chemical Engineering Journal vol 170 no 1pp 184ndash193 2011

[37] Y Berbar M Amara and H Kerdjoudj ldquoEffect of adsorptionof polyethyleneimine on the behaviour of anion exchangeresinrdquo Procedia Engineering vol 33 pp 126ndash133 2012

[38] E Altiok D Baycin O Bayraktar and S Ulku ldquoIsolation ofpolyphenols from the extracts of olive leaves by adsorption onsilk fibroinrdquo Separation and Purification Technology vol 62no 2 pp 342ndash348 2008

[39] D R Kammerer Z H Saleh R Carle and R A StanleyldquoAdsorptive recovery of phenolic compounds from applejuicerdquo European Food Research amp Technology vol 224 no 5pp 605ndash613 2007


TribologyAdvances in

Hindawiwwwhindawicom Volume 2018


International Journal ofInternational Journal ofPhotoenergy


Journal of

Chemistry


Advances inPhysical Chemistry

Hindawiwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2018

Bioinorganic Chemistry and ApplicationsHindawiwwwhindawicom Volume 2018

SpectroscopyInternational Journal of


Hindawi Publishing Corporation httpwwwhindawicom Volume 2013Hindawiwwwhindawicom

The Scientific World Journal

Volume 2018

Medicinal ChemistryInternational Journal of


NanotechnologyHindawiwwwhindawicom Volume 2018

Journal of

Applied ChemistryJournal of



Biochemistry Research International


Enzyme Research


Journal of

SpectroscopyAnalytical ChemistryInternational Journal of


MaterialsJournal of



BioMed Research International Electrochemistry

International Journal of


Na

nom

ate

ria

ls


Journal ofNanomaterials

Submit your manuscripts atwwwhindawicom

predict the kinetics and modelling in the extraction of ly-copene in tomato waste using organic solvents Pelegrsquosmodel adequately describes the rate of the adsorptionprocess adsorption extent and exhaustive time of thecompounds studied Meanwhile the Langmuir andFreundlich models can be used to predict the adsorptionisotherm for the compounds studied

In order to reduce the unpleasant odor of noni juice butat the same time conserve the antioxidants during the de-acidification process it is important to understand the in-teraction of both unpleasant odor compounds of organicacids and antioxidants with ion exchange resins (us thisstudy was carried out to determine the adsorption charac-teristics between organic acids (octanoic acid and hexanoicacid) and phenolic compounds (rutin scopoletin andquercetin) onto a weakly basic ion exchange resin usinga model system

2 Materials and Methods

21 Materials Weak base anion exchanger Amberlite IRA67 and standards of octanoic acid hexanoic acid rutinscopoletin and quercetin were purchased from Sigma-Aldrich Corporation (St Louis MO USA) AmberliteIRA 67 was used due to its higher performance for theadsorption of some organic acid compounds as reported byHaslaniza et al [4] Rutin scopoletin and quercetin wereused due to its existence in all noni fruits and commercialnoni juices from different countries all over the world al-though at different ranges of concentration [10] Methanol(HPLC grade purity gt999) was purchased from FisherScientific (New Jersey USA)

22 Adsorption Studies of Organic Acids and PhenolicCompounds (e adsorption studies of organic acids andphenolic compounds onto weakly basic ion exchanger resinwere carried out in Erlenmeyer flasks where 01 g of the dryanion exchanger and 002 L of each sample which wereoctanoic acid (250 500 750 and 1000mgL) hexanoic acid(100 200 300 and 400mgL) rutin (25 50 75 and100mgL) scopoletin (25 50 75 and 100mgL) andquercetin (25 50 75 and 100mgL) were added without pHadjustment (e flasks were agitated in an orbital shaker(WiseCube Daihan Scientific Korea) at a constant speed of120 rpm for 180min at room temperature (25degC) to achieveequilibrium [11] Each of the organic acid after equilibriumwas measured using a gas chromatographer (Agilent ModelHP6890 USA) equipped with a flame ion detector (FID)Each of the phenolic compounds was measured using high-performance liquid chromatography (HPLC) (e amountof organic acids and phenolic compounds adsorbed atequilibrium qe (mgg) were calculated using the followingequation

qe Co minusCe

wtimes V (1)

where Co and Ce were the concentrations (mgL) of eachorganic acid and phenolic compound at the beginning

and after equilibrium respectively V was the volume ofthe solution (L) and w was the mass of the dry anionexchanger (g)

23 Kinetics of Liquid-Liquid Adsorption (e Peleg modelhas been used to describe adsorption processes in variousfoods [12ndash14] (e adsorption curves (concentration of eachorganic acidphenolic compound versus time) could bedescribed by a model proposed by Peleg [15] which in case ofadsorption would assume the form as stated below

C(t) Co +t


where C(t) is the concentration of each organicacidphenolic compound at time t (mgg) t is the adsorptiontime (min) Co is the initial concentration of each organicacidphenolic compound at time t 0 (mgg) K1 is Pelegrsquosrate constant (minmiddotgmg) and K2 is Pelegrsquos capacity constant(gmg) Equation (2) was used in the final form while Co 0in all experiments

C(t) t


K1 is Pelegrsquos rate constant which is related to adsorptionrate (B0) at the very beginning (t t0)

B0 1

K1

mgg

middot min1113888 1113889 (4)

K2 is Pelegrsquos capacity constant which is related tomaximum adsorption yield or equilibrium concentration ofadsorbed compounds (Ce) When trarrinfin

C(trarrinfin) Ce 1

K2

mgg

1113888 1113889 (5)

24Determination ofOrganicAcids Organic acids (octanoicacid and hexanoic acid) were extracted using Gas Chro-matography Solid Phase Microextraction (GC-SPME) (eSPME inlet used was 075mm (Supelco) SPME needlecontained divinylbenzene-carboxen-polydimethylsiloxane(DVB-CAR-PDMS) fiber (StableFlex Supelco) (e sam-ple (1mL) was added into a headspace vial sealed withsilicone septum and layered with Teflon-faced silicone septa(Supelco USA) (en it was heated in a waterbath(Memmert Germany) at 53degC for 12min [16] After heatingSPME needle was directly injected through the septum intothe vial for 10min After extraction the needle was removedfrom the vial and injected to the gas chromatographer

Gas chromatography was performed using a gas chro-matographer mass spectrometry (Agilent Model HP6890USA) equipped with a flame ion detector (FID) and splitlessinjector Separation of the organic compounds was doneusing a capillary column HP-5 (30mtimes 025 id 025 μm filmthickness JampW Scientific Pte Ltd USA) Oven temperaturewas programmed according to the method of Zamboninet al [17] with the following parameters initial temperaturewas 50degC for 2min before it raised to 80degC at 20degCmin for






Ce

qe

1qm

Ce +1

KLqm (6)



qe KF + C1ne (7)




RL 1

1 + KLCo (9)



RMSD

1n


1113970

(10)









0

20

40

60

80

100

120

Adso

rptio

n ca

paci

ty q

(mg

g)

250 mgL500 mgL

750 mgL1000 mgL

(a)

0

10

20

30

40

50

Adso

rptio

n ca

paci

ty q

(mg

g)


100 mgL200 mgL

300 mgL400 mgL

(b)





















0

1

1

2

2

3Ad

sorp

tion

capa

city

q (m

gg)


25 mgL50 mgL

75 mgL100 mgL

(a)

0

1

1

2

2

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(b)

0

1

1

2

2

3

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(c)










K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD






























Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








Ce

qe

1qm

Ce +1

KLqm (6)



qe KF + C1ne (7)




RL 1

1 + KLCo (9)



RMSD

1n


1113970

(10)









0

20

40

60

80

100

120

Adso

rptio

n ca

paci

ty q

(mg

g)

250 mgL500 mgL

750 mgL1000 mgL

(a)

0

10

20

30

40

50

Adso

rptio

n ca

paci

ty q

(mg

g)


100 mgL200 mgL

300 mgL400 mgL

(b)





















0

1

1

2

2

3Ad

sorp

tion

capa

city

q (m

gg)


25 mgL50 mgL

75 mgL100 mgL

(a)

0

1

1

2

2

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(b)

0

1

1

2

2

3

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(c)










K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD






























Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








0

20

40

60

80

100

120

Adso

rptio

n ca

paci

ty q

(mg

g)

250 mgL500 mgL

750 mgL1000 mgL

(a)

0

10

20

30

40

50

Adso

rptio

n ca

paci

ty q

(mg

g)


100 mgL200 mgL

300 mgL400 mgL

(b)





















0

1

1

2

2

3Ad

sorp

tion

capa

city

q (m

gg)


25 mgL50 mgL

75 mgL100 mgL

(a)

0

1

1

2

2

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(b)

0

1

1

2

2

3

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(c)










K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD






























Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








0

1

1

2

2

3Ad

sorp

tion

capa

city

q (m

gg)


25 mgL50 mgL

75 mgL100 mgL

(a)

0

1

1

2

2

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(b)

0

1

1

2

2

3

Adso

rptio

n ca

paci

ty q

(mg

g)


25 mgL50 mgL

75 mgL100 mgL

(c)










K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD






























Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls











K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD







K1(minmiddotgmg)

K2(gmg) R2 RMSD






























Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls

















Octanoic acid

250 07672500 06223750 052341000 04517

Hexanoic acid

100 07074200 05472300 04462400 03767

Rutin

25 0064250 0033275 00224100 00169

Scopoletin

25 0009450 0007075 00047100 00035

Quercetin

25 00138550 00069775 000466100 000350








d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls










d dc

b b a a aa

a a a

dd c f b

b a

a

a

a a a


020406080

100120140160180200

Adso

rptio

n ca

paci

ty q

(mg

g)

3 4 5

Con

trol B 2 8 10

Con

trol A

96 117pH values



d d

c

b a a a a a a a a

0

100

200

300

400

500

600Ad

sorp

tion

capa

city

qe (

mg

g)

102 4

Con

trol B

Con

trol A

6 7 9 1153 8pH values

(a)

d d

c

ba a a a a a a a

Con

trol B 2 4

Con

trol A

76 9 115 1083

pH values

0

50

100

150

200

250

300

Adso

rptio

n ca

paci

ty q

(mg

g)

(b)







4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls








4 Conclusion



Data Availability




Acknowledgments


References
















































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls









































Journal of

Chemistry





Journal of

Volume 2018






Volume 2018




Journal of






Enzyme Research


Journal of



MaterialsJournal of






Na

nom

ate

ria

ls




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