research article influence of alkali treatment on the surface area of aluminium...

Research ArticleInfluence of Alkali Treatment on the Surface Area ofAluminium Dross

N S Ahmad Zauzi1 M Z H Zakaria1 R Baini1 M R Rahman1

N Mohamed Sutan2 and S Hamdan3

1Department of Chemical Engineering and Sustainability Energy Faculty of Engineering Universiti Malaysia Sarawak94300 Kota Samarahan Sarawak Malaysia2Department of Civil Engineering Faculty of Engineering Universiti Malaysia Sarawak 94300 Kota SamarahanSarawak Malaysia3Department of Mechanical Engineering and Manufacturing Faculty of Engineering Universiti Malaysia Sarawak94300 Kota Samarahan Sarawak Malaysia

Correspondence should be addressed to N S Ahmad Zauzi aznsyuhadaunimasmy

Received 18 March 2016 Accepted 25 May 2016

Academic Editor Guocheng Lv

Copyright copy 2016 N S Ahmad Zauzi 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

Aluminium dross is an industrial waste from aluminium refining industry and classified as toxic substances However the disposalof dross as a waste is a burden to aluminium manufacturer industries due to its negative effects to the ecosystem surface andground waterTherefore the purpose of this study is to evaluate the influence of sodium hydroxide (NaOH) on the surface area andpore size of aluminium dross There were 3 stages in the treatment activities which were leaching precipitation and calcinationprocess The optimum result from this study was the surface area of aluminium dross increases from 101m2g up to 800m2g at40∘C 1NaOH and 15-minute reaction timeThus aluminiumdross has a potential to be converted into other usefulmaterial suchas catalyst and absorbent The benefit of this research is that the hazardous industrial waste can be turned into wealth to be used inother applications such as in catalytic activities and absorber inwaste water treatment Further investigation on the physicochemicalof aluminium dross with different acid or alkali should be conducted to get deeper understanding on the aluminium dross as acatalyst-type material

1 Introduction

Aluminium dross is one type of the industrial wastes whichare generated in a recycle of an aluminium recycle processThere are three types of aluminium dross which are blackdross white dross and salt cake White dross is gener-ated in aluminium smelting industries while black drossand salt cake are generated in the aluminium recyclingindustries Amount and the formation of these substancesdepend on several factors such as the type and quality ofinput materials operating conditions the type of technologyand furnace applied The overall chemistry depends on thealloying elements present in the molten aluminium and themetallurgical process [1] Generally this dross may containAl2O3 AlN Al

4C3 SiO2 MgO Al and minor quantities of

Si [2] According to Sultana et al [3] it was estimated that15ndash25 kg of dross is produced per metric tonne of moltenaluminium and [4] stated that throughout the world it wasestimated that 5 million tonnes of an aluminium dross wasgenerated every year

Aluminium dross is classified as a toxic industrial wasteand it requires a proper treatment before it can be dischargedMajority of aluminiumdross is disposed in open landfill sitesand this activity can cause harm to the environment due to thetoxic ions there is possibility of toxin ions leached out fromthe disposed aluminium dross into the ground water whichcan cause pollution [4ndash6] This substance is usually treatedas a landfilled solid waste [6] The disposal cost of this wastecan be expensive RM 200000 per tonne will be charged bythe approved local disposal waste company for the disposal in

Hindawi Publishing CorporationAdvances in Materials Science and EngineeringVolume 2016 Article ID 6306304 4 pageshttpdxdoiorg10115520166306304

2 Advances in Materials Science and Engineering

Table 1 Chemical composition of raw aluminium dross

Composition SiO2Al2O3Fe2O3MgO SO

3CaO TiO

2Na2O

wt 12 898 054 084 015 041 0022 031

Malaysia [7] A large amount of aluminium dross has neverbeen treated properly prior to discharge due to the high costof treatment and transportation

Although aluminium dross is a type of waste severaluseful usages have been discovered such as filler in compos-ite being used in refractories industry and also being usedas adsorbent Aluminium dross can be leached with copperchloride water solution to obtain aluminium oxychlorideAl(OH)Cl

2 and then can be further treated with aluminium

hydroxide to obtain aluminium chloride Al2(OH)5Cl which

can be used as a coagulant in water treatment process [8]Other than that aluminium dross can be used as a deoxidizerto remove oxygen in the steel-manufacturing process andused as aggregate in cement processing [4]

More studies on treatment process for aluminium drossare necessary to increase the possibility of recycling thisdangerous waste into useful products Therefore the aim ofthis work is to study the possibility of producing commercialcatalyst from aluminium dross In this work aluminiumdross has been treated using different concentration ofsodium hydroxide for different temperatures and reactiontime

2 Experimental

Aluminiumdross in this studywas obtained from aluminiumsmelting industry Press Metal Company which is located inSamalaju Industrial Park Bintulu Sarawak Three process-ing stages were applied to aluminium dross leaching withsodium hydroxide precipitation with hydrogen peroxideand calcination The first process was carried out by adding10 g of aluminium dross with size lt 300120583m to a 250mLof sodium hydroxide (NaOH) with concentrations of 15 10 and 20 stirring time of 15 minutes 30 minutes45 minutes and 60 minutes and temperatures of 25∘C40∘C 55∘C and 70∘C The next process was the precipitationwith hydrogen peroxide by adding 250mL of 30 hydrogenperoxide (H

2O2) to samples The mixtures were stirred for

30 minutes at room temperature filtered and washed withdistilled water In the final stage the samples were calcined attemperature of 600∘C for 3 hours

The chemical composition of raw and treated aluminiumdross was analysed using X-Ray Fluorescence Spectroscopy(XRF) equipment (Bruker S4 EXPLORER X-Ray Fluores-cence) The surface area and pore size of aluminium drosswere determined using BET surface analysis (QuantachromeInstruments Co Ltd)

3 Results and Discussion

The chemical composition of aluminium dross (wt)obtained from XRF is given in Table 1 It was found thatalmost 90 of the raw material consists of Al

2O3and the

Table 2 Effect of time on the surface area of aluminium dross attemperature of 25∘C and concentration of NaOH at 1

Time (mins) 15 30 45 60Surface area (m2g) 79 49 28 28

Table 3 Effect of temperature on the surface area of aluminiumdross at reaction time of 15 minutes and concentration of NaOH at1

Temperature (∘C) 25 40 55 70Surface area (m2g) 79 80 51 47

Table 4 Effect of NaOH concentration on the surface area ofaluminium dross at reaction time of 15 minutes and temperature at25∘C

NaOH () 1 5 10 20Surface area (m2g) 79 38 74 21

remaining 10 consists of SiO2 Fe2O3 MgO SO

3 CaO

TiO2 and Na

2O

In the first stage of treatment hydrogen gas was formedduring the leaching process with sodium hydroxide Thedetails of reactions in the first and second stages are given by(1)ndash(3) and (4) respectively

Al + 3H2O +NaOH 997888rarr NaAl (OH)4 +

3

2

H2

(1)

NaAl (OH)4997888rarr Al (OH)

3+

3

2

H2

(2)

The overall reaction can be summarized as follows

Al + 3H2O 997888rarr Al (OH)

3+

3

2

H2

(3)

NaAlO2+ 2H2O2997888rarr Al (OH)

3+NaOH +O

2 (4)

31 BET Surface Area The surface area of the raw aluminiumdross analysed using BET surface analysis was found to be10061m2g while the surface area for treated samples isgiven in Tables 2ndash4 Table 2 represents the effect of timeon the surface area of aluminium dross with temperature of25∘C and concentration of NaOH at 1 Table 3 representsthe effect of temperature on the surface area of aluminiumdross with time at 15 minutes and temperature at 25∘Cconcentration of NaOH at 1 Table 4 represents the effectof NaOH concentration on the surface area of aluminiumdross with time of 15 minutes at 25∘C Based on Tables 2ndash4it was found that all the treated samples have larger surfacearea up to 700 compared to untreated oneThis occurrencecan be explained due to the process of dealumination and itwill cause the disintegration surface of aluminium dross [9]Besides the increases of BET surface area with the presenceof alkali are due to the production of finely dispersed siliconoxides from destruction of mineral structures and removal

Advances in Materials Science and Engineering 3

BET surface area isotherm

0

1

2

3

4

5

6

Volu

me

STP

(cc

g)

02 04 06 08 1 120Relative pressure PPo

Figure 1 Isotherms of raw aluminium dross

of amorphous of Al or silica components and thus increasethe surface pores [10] A large value of BET surface area willreflect the catalytic activity of the material

On the effect of time it shows that the surface area ofaluminium dross increases when aluminium dross stirred for15 minutes but as the time increases until 60 minutes it maybe seen that the surface area of aluminium dross decreasesThe catalytic activity may reach a maximum at 15 minutes ofreaction time whereas the effectiveness of catalysts could bereducing as the time increases [11]

This experiment was carried out with different tempera-tures which are 25∘C 40∘C 55∘C and 70∘C respectively InTable 3 at 25∘C it shows the surface area of aluminium drossincreases from 10m2g to 79m2g But as the temperatureincreases up to 70∘C the pattern of the surface area decreasesAt higher temperature aluminium dross was found to beagglomerated thus the surface of aluminium dross may beruptured due to high temperature [11 12]

Table 4 shows the effect of concentration of sodiumhydroxide on the surface area of aluminium dross In thisexperiment the concentrations of sodiumhydroxide used are1 5 10 and 20 respectively With the concentrationof 1 of sodium hydroxide the surface area of aluminiumdross increases from 10m2g to 79m2g From the tablethe surface area of aluminium dross decreases as the con-centration of sodium hydroxide increases Other than thatthe maximum concentration for leaching process is at 1whereas the surface area of aluminium dross decreases whenthe concentration increases due to saturation of aluminiumdross at higher NaOH concentration [11]

Figures 1 2 3 and 4 are the nitrogen adsorption anddesorption isotherms for raw aluminium dross and treatedwith 1 concentration of sodium hydroxide stirring timeof 30 minutes and leaching temperatures of 25∘C 40∘Cand 55∘C respectively Figures show that the amount of N

2

absorbed increases with the relative pressure The slope ofthe curve decreases as the relative pressure decreases whichmay indicate that the amount of N

2absorbed is reaching the

equilibrium state According to International Union of Pureand Applied Chemistry (IUPAC) those isotherms can beclassified as type I which indicates adsorption and desorptionon a microporous solid with pore size below 2 nm Thistype of isotherms showed high uptakes of nitrogen gas at


05

10152025303540

Volu

me

STP

(cc

g)


Figure 2 Isotherms of aluminium dross treated with 1 of NaOHat 30 minutes and temperature of 25∘C


05

101520253035

Volu

me

STP

(cc

g)




02 04 06 08 1 1200

10

20

30

40

50

60

Volu

me

STP

(cc

g)

Relative pressure PPo


relatively low pressure due to the narrow pore width and highadsorption potential

4 Conclusion

The characteristics of aluminium dross after being treatedwith different concentrations of NaOH at different reactiontime and temperatures were studied It shows that at 15minutes the surface area of aluminium dross increases butas the time increases the surface area decreases It alsoshows that at 1 concentration of NaOH the surface areaof aluminium dross increases but it seems to decrease as theconcentration of NaOH increases Surface area of aluminium


dross also reaches a maximum catalytic activity when thetemperature is at 25∘C but when the temperature increasesit shows decreasing of the surface area of aluminium drossdue to the rupture of pores N

2adsorption-desorption shows

that aluminiumdross was type I which ismicroporous solidsTherefore based on the BET surface analysis aluminiumdross has a potential to be a catalyst-type material andreduce the waste of aluminium dross For further study it isrecommended to focus on other physicochemical propertiesof treated aluminium dross

Competing Interests

The authors declare that the grant scholarship andorfunding mentioned in Acknowledgments do not lead to anyconflict of interests Additionally the authors declare thatthere is no conflict of interests regarding the publication ofthis paper

Acknowledgments

The authors are thankful to theMinistry of Higher Educationfor funding under FRGS12015SG06UNIMAS031 andUniversiti Malaysia Sarawak

References

[1] HN Yoshimura A P Abreu A LMolisani A CDeCamargoJ C S Portela and N E Narita ldquoEvaluation of aluminum drosswaste as raw material for refractoriesrdquo Ceramics Internationalvol 34 no 3 pp 581ndash591 2008

[2] J C E Bocardo and J T Torres ldquoDevelopment of mul-litezirconia composites from amixture of aluminum dross andzirconrdquoCeramics International vol 35 no 2 pp 921ndash924 2009

[3] U K Sultana F Gulshan M A Gafur and A S W KurnyldquoKinetics of recovery of alumina from aluminium casting wastethrough fusion with sodium hydroxiderdquo American Journal ofMaterials Engineering and Technology vol 1 no 3 pp 30ndash342013

[4] NMurayama IMaekawaHUshiro TMiyoshi J Shibata andM Valix ldquoSynthesis of various layered double hydroxides usingaluminum dross generated in aluminum recycling processrdquoInternational Journal of Mineral Processing vol 110-111 pp 46ndash52 2012

[5] B R Das B Dash B C Tripathy I N Bhattacharya and S CDas ldquoProduction of 120578-alumina from waste aluminium drossrdquoMinerals Engineering vol 20 no 3 pp 252ndash258 2007

[6] S-J Yoo D-H Kwak S-I Lee et al ldquoKinetics of aluminumdross dissolution in sec-butyl alcohol for aluminum sec-butoxiderdquo Advanced Powder Technology vol 22 no 5 pp 617ndash622 2011

[7] M S Meor Yusoff and W P Masliana Muslim ldquoA waste towealth study on converting aluminium dross schedule wasteinto 120574 and 120572 aluminardquo in Recent Advances in EnvironmentEcosystems and Development pp 17ndash21 2009

[8] B Lucheva T Tsonev and R Petkov ldquoNon-waste aluminumdross recyclingrdquo Journal of the University of Chemical Technol-ogy and Metallurgy vol 40 no 4 pp 335ndash338 2005

[9] S Kumar A K Panda and R K Singh ldquoPreparation andcharacterization of acids and alkali treated kaolin clayrdquo Bulletin

of Chemical Reaction Engineering amp Catalysis vol 8 no 1 pp61ndash69 2013

[10] V Lakevics V Stepanova I Skuja I Dusenkova and A RuplisldquoInfluence of alkali and acidic treatment on sorption propertiesof latvian illite claysrdquo Key Engineering Materials vol 604 pp71ndash74 2014

[11] V R Choudhary and M G Sane ldquoEffect of preparation condi-tions of Raney Nickel on its catalytic properties for slurry phasehydrogenation of o-nitrophenol to o-aminophenolrdquo IndianJournal of Chemical Technology vol 5 no 4 pp 199ndash208 1998

[12] Q Liu R Xin C Li C Xu and J Yang ldquoApplication of redmud as a basic catalyst for biodiesel productionrdquo Journal ofEnvironmental Sciences vol 25 no 4 pp 823ndash829 2013

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NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

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Nano

materials


Journal ofNanomaterials


Table 1 Chemical composition of raw aluminium dross

Composition SiO2Al2O3Fe2O3MgO SO

3CaO TiO

2Na2O

wt 12 898 054 084 015 041 0022 031

Malaysia [7] A large amount of aluminium dross has neverbeen treated properly prior to discharge due to the high costof treatment and transportation

Although aluminium dross is a type of waste severaluseful usages have been discovered such as filler in compos-ite being used in refractories industry and also being usedas adsorbent Aluminium dross can be leached with copperchloride water solution to obtain aluminium oxychlorideAl(OH)Cl

2 and then can be further treated with aluminium

hydroxide to obtain aluminium chloride Al2(OH)5Cl which

can be used as a coagulant in water treatment process [8]Other than that aluminium dross can be used as a deoxidizerto remove oxygen in the steel-manufacturing process andused as aggregate in cement processing [4]

More studies on treatment process for aluminium drossare necessary to increase the possibility of recycling thisdangerous waste into useful products Therefore the aim ofthis work is to study the possibility of producing commercialcatalyst from aluminium dross In this work aluminiumdross has been treated using different concentration ofsodium hydroxide for different temperatures and reactiontime

2 Experimental

Aluminiumdross in this studywas obtained from aluminiumsmelting industry Press Metal Company which is located inSamalaju Industrial Park Bintulu Sarawak Three process-ing stages were applied to aluminium dross leaching withsodium hydroxide precipitation with hydrogen peroxideand calcination The first process was carried out by adding10 g of aluminium dross with size lt 300120583m to a 250mLof sodium hydroxide (NaOH) with concentrations of 15 10 and 20 stirring time of 15 minutes 30 minutes45 minutes and 60 minutes and temperatures of 25∘C40∘C 55∘C and 70∘C The next process was the precipitationwith hydrogen peroxide by adding 250mL of 30 hydrogenperoxide (H

2O2) to samples The mixtures were stirred for

30 minutes at room temperature filtered and washed withdistilled water In the final stage the samples were calcined attemperature of 600∘C for 3 hours

The chemical composition of raw and treated aluminiumdross was analysed using X-Ray Fluorescence Spectroscopy(XRF) equipment (Bruker S4 EXPLORER X-Ray Fluores-cence) The surface area and pore size of aluminium drosswere determined using BET surface analysis (QuantachromeInstruments Co Ltd)

3 Results and Discussion

The chemical composition of aluminium dross (wt)obtained from XRF is given in Table 1 It was found thatalmost 90 of the raw material consists of Al

2O3and the

Table 2 Effect of time on the surface area of aluminium dross attemperature of 25∘C and concentration of NaOH at 1

Time (mins) 15 30 45 60Surface area (m2g) 79 49 28 28

Table 3 Effect of temperature on the surface area of aluminiumdross at reaction time of 15 minutes and concentration of NaOH at1

Temperature (∘C) 25 40 55 70Surface area (m2g) 79 80 51 47

Table 4 Effect of NaOH concentration on the surface area ofaluminium dross at reaction time of 15 minutes and temperature at25∘C

NaOH () 1 5 10 20Surface area (m2g) 79 38 74 21

remaining 10 consists of SiO2 Fe2O3 MgO SO

3 CaO

TiO2 and Na

2O

In the first stage of treatment hydrogen gas was formedduring the leaching process with sodium hydroxide Thedetails of reactions in the first and second stages are given by(1)ndash(3) and (4) respectively

Al + 3H2O +NaOH 997888rarr NaAl (OH)4 +

3

2

H2

(1)

NaAl (OH)4997888rarr Al (OH)

3+

3

2

H2

(2)

The overall reaction can be summarized as follows

Al + 3H2O 997888rarr Al (OH)

3+

3

2

H2

(3)

NaAlO2+ 2H2O2997888rarr Al (OH)

3+NaOH +O

2 (4)

31 BET Surface Area The surface area of the raw aluminiumdross analysed using BET surface analysis was found to be10061m2g while the surface area for treated samples isgiven in Tables 2ndash4 Table 2 represents the effect of timeon the surface area of aluminium dross with temperature of25∘C and concentration of NaOH at 1 Table 3 representsthe effect of temperature on the surface area of aluminiumdross with time at 15 minutes and temperature at 25∘Cconcentration of NaOH at 1 Table 4 represents the effectof NaOH concentration on the surface area of aluminiumdross with time of 15 minutes at 25∘C Based on Tables 2ndash4it was found that all the treated samples have larger surfacearea up to 700 compared to untreated oneThis occurrencecan be explained due to the process of dealumination and itwill cause the disintegration surface of aluminium dross [9]Besides the increases of BET surface area with the presenceof alkali are due to the production of finely dispersed siliconoxides from destruction of mineral structures and removal



0

1

2

3

4

5

6

Volu

me

STP

(cc

g)








2





05

10152025303540

Volu

me

STP

(cc

g)




05

101520253035

Volu

me

STP

(cc

g)




02 04 06 08 1 1200

10

20

30

40

50

60

Volu

me

STP

(cc

g)




4 Conclusion






Competing Interests


Acknowledgments


References





















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





0

1

2

3

4

5

6

Volu

me

STP

(cc

g)








2





05

10152025303540

Volu

me

STP

(cc

g)




05

101520253035

Volu

me

STP

(cc

g)




02 04 06 08 1 1200

10

20

30

40

50

60

Volu

me

STP

(cc

g)




4 Conclusion






Competing Interests


Acknowledgments


References





















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







Competing Interests


Acknowledgments


References





















CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article influence of alkali treatment on the surface area of aluminium...

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