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AdvancesinScienceandEngineeringfor BrackishWaterandSeawaterDesalination

May 8-12,2010GrandHotel Michele,Cetraro(Calabria);Italy

Conference Chairs

Prof. Enrico DrioliInstituteonMembraneTechnology(ITM-CNR)

UniversityofCalabria,Italy

Dr.NormanLiNLChemicalTeehnology,Ine.,USA

EXTENDEDASSTRACTS

fCI~EngineeringConferencesInternational32Broadway,Suite314-NewYork, NY 10004,USAPhone:1-212 -514-6760,Fax: 1-212 -514-6030

www.engeonfintl.org-info@engconfintl.org

(Sorption kinetics and equilibrium of nickel ions from water on bone

char

Didilia 1.Mendoza-Castillo 1,Karolina Castro-Chávez 2,Juan Jáuregui-Rincón 1,Adrián Bonilla-Petriciolet 2'

1Departamento de Ingeniería Bioquímica, Universidad Autónoma de Aguascalienles, Av. Universidad 940,Ciudad Universitaria, c.P. 20131, Aguascalientes. México

2Departamento de Ingeniería Química y Bioquímica, InstitUtoTecnológico de Aguascalientes, Av. Tecnológico1801, Fracc. Bona Gens Ote., C.P. 20256, Aguascaliemes, México I

l2etriciolet!i!ll101nliliLj;~11I1

Introduction

Water polIution by heavy metals is an imp0l1ant topie in the eontext of the environment'proteetion andhumanhealth due to their bioaccumulation, non biodegradableproperties,al1dtoxicity even at low concentrations. Several metallic species have a potentially damagingeffect on human physiology and other biological systems when the tolerance levels areexeeeded.For example,the ehronic exposureto nickel (Ni+2) may causecancerof lungs andbone. Hence,the removal ofNi+2 ions frolh industrial efflOents before its disehargeinto theenvironment hasbecomean important andnecessarytask to reduceenvironmentalimpact andto prevent humanhealth problems. The eonventional methodsfor heavy metal removal fromwastewaters involve physieal, chemical, 01' biological processes~In particular, sorptionprocessis consideredas an e!Tective and economical method for heavy metal removal fromwastewaters.Severalstudies have shown that different synthetie and naturalsorbentscan beusedfor thispurpose(1]. Bone char (BC) is a promising and low-cost sorbentthat canbe usedfor wastewaterstreatmentinc1uding the removal of heavy metals (2-4]. However, to the bestof our knowledge,theuseof BC for theremovalof Ni+2 ions hasnot beenreported.Thispapel'reportsthesorption study of Ni+2ions fram aqueoussolutions onto acid-pretreatedbonechal' (A-BC). Kinetic and equilibrium sorption experiments were performed by varyingexperimental parameters such as pH, contact time, ¡nitial metal concentration, andtemperature.The experimental data were analyzedusing c1assicalsorption models. Finally,ourresultsshowthatA-BCis analternativesorbentto removeNi+2 ionsfromwastewaters.

MethodologyA commercialBC derived fram bovine boneswas used in this study. Raw BC was washcdwith deionized water and treated with HNO) 1 N. This pretreatment was perfOlmed toincreasethesurfacearea and to remove impurities.Subsequently,the sorbentwas dried al 110°C during5 handit wassievedto obtaina40-50meshparticlesize.To studythe uptake 01'Ni+2onto A-BC, batch sorption experimentswerecaniedoutat 200rpmusinga sorbentratíoof 4 gIL. Kinetic experiments were performedto establish the equilibriumtime and lo studythe uptakerateat different conditions of pH, temperatllre,and metal concentration.The effectof pH was studiedin the range2.0- 5.0at30°Cand using metal concentrationsof 50, 80 and100 mg/L, respectively. On the other hand, the effeet of temperalllre was also investigaled at25, 30 and 40°C employingsolutions with ¡nilíal concentrationsin the range \O- 100mglLand pH 5. At describedconditions, the sorption isotherms were obtained to detellTline thesorption capacily of A-BC and to identify [he optimum conditions for Ni+2 removal. Thesorption experimentaldata were con'elated using several kinetic and isotherm equations.Specifically,the pseudo-firstorder, pseudo-secondorder and Elovich equationswere usedtofit the kinetic data, while the equilibrium data were adjusted to the Langmuir, Freundlich and

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'SiPSmOdr Jr data correlation, a non-linearregressionanalysiswasused.Finally, the pointof zero charge(pHpzc).textural properties,surface morphology andchemical composition ofA~BC weredetelmined.

Results and discussionThe characterizationresults indicate that A-BC has a meso-porousstructure and a mono-

modal poredistribution with an averagepartide size of 34.5 Á, 810m2/gof surface area,andits pH~zcis 4.0. With respect to the morphology, A-BC appearsto havea homogeneousporestructure (seeFigure 1). According to the EDS analysis. this materialis mainly composedofC, O andCa.

00.....('<)E()

O-E;j"O>'O

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'O<1;

"O ¡a)260

130

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o0.00 0.25 0.50

Relative pressure.PIPo,

0.75 1.00

I

Figure 1. (a) N2 sorption-desorption isotherms (at 77.35 K) and pore size distribution'ofA-BC. (b) Scanningelectron micrographsof A-BC before sorption of Ni+2ions.

With illustrative purposes.Figure 2 showsth,ekinetic data obtainedfor the Ni+2uptake ontoA-BC where the effect of contact time. initial metal concentration.and pH are considered.These results indicated that the sorption rate of metal ions is fast within the first hourS ofcontact time. Thereafter, the sorption rates decrea~egradually and kinetics tend toward

equilibrium at 24 h'for all testedconditions. The kinetic data suggestthat most of the metal

106

t

( removal takes place on external sUI'fi¡ce of A-Be. As expected, the metal So( .1is stronglyinfluenced by the initial concentration where an increasein the initial metal content resultedin an increaseof Ni+2uptake (see Figure 2a). Additionally, the metal uptake is cIearly pHdependentand the greatestsorption occurredat high pH. The metal uptakesranged from 2.0to 6.0 mg/g whenpH increasedfram 2 to 5 units, respective1y.The decreaseof metal uptakeat pH < 5 canbe attributed to the pratonation of the active graups and the competition of H+with the metal ions for the bincling sites in A-BC surface. In all expelÍments, the removal ofNi+2 ions rangedfrom 8 to 90% where the maximum sorption capacity occUlTedatpH 5. Onthe other hand,theeffect of temperatureon the Ni+2 sorption is shown in Figure 3. It appearsthat the sorption capacity is essentially ¡ndependent of temperature at the saturationconditions. Wíth respectto the mocleling of sOlvtiondata, the statistical analysisindicates thatthe pseudo-secondorder kinetic satisfactorily describes the rate of metal uptake, while theSips model is proper for correlation of the equilibrium data.

figure 2. Effect of inítial metal concentratíon,contact time, and temperatureon Ni+2 uptakeby A-BC in aqueoussolution. Experimental conditions: sorbent ratio of 4 giL. 30°C and 200rpm. (a) Initial concentratian(mg/L): (O)50, (o) 80, and (6.) 100; pH: 5. (b) pH: ()IC)2, (M 3,(o) 4 and (0)-5.andinitíal Ni+1concentrationof 50 mg/L.

107

100 ). 75 6 1\ 6 6 6

O O O

50

O O O O O O...¡ 25bJ¡E¿ O.8e o 6 12 18 24ddJ

b)()eo 48 ¡(;+: :1: :K :K :Ku :K] 666 6. 6 6.u

8 e gz 32 8 8 e

16

O

O 6 12 18 24Time,h

( (6.0

4.5~o

~ ~ 4!1 ID

~fJel,EJ

..>::oso..:::

3.0

o ~¡g

Q3..>::ui

1.5

0.0o 15 30 45

Equiíibriumco~centration,mg/L

60

Figure3. Effectof temperatureon Ni+2uptakeby A-BC in aqueoussolution.Experimentalconditions:sorbentratioof4 giL, 200rpmandpH5.Temperature(OC):(o) 25,(O)30and(8)40.

Conclusions

The maximum sorption capacities obtained in this study are higher than those reported fol'other sorbentssuch aschitosan (2.04 mg/g), zeolites(0.48 mg/g) and c1ays(3.90 mg/g) [6].Theseresultssuggestthat A-BC can be consideredasanalternative sorbentfor Iheremoval ofNi+2ions I'rom industrialeffluents.

References

[1] 1.M. Días,M.C.M.Alvim-Ferraza,M.F. Almeida,J. Rivera.Utrilla,M. Sánchez.Polo,.Wastematerialsfor activatedcarbonpreparationandits usein aqueous-phasetreatmen!:Areview,Journalof EnvironmentalManagement85(2007)833-846.[2] S.Dahbi,M. Azzí,M. DelaGuardia,Removalof hexavalentchromiumfromwastewatersbybonecharcoal,Fresenius'Journalof Ana!yticalChemistry363(1999)404-407.[3] K.K.H. Choy,G. McKay,Sorption01'cadmium,copper,andzinc ionsantabonecharusingCrankdiffusionmodel,Chemosphere60(2005)1141-1150.[4] C.w. Cheung,K.K.H. Choy, J.F. Porter,G. Mckay, Empirical MulticomponentEquilibriumandFilm-PareModelrol' theSorption01'Copper,CadmiumandZincantaBoneChal',Adsorptionl1(2005)15-29. .[5] R.R.Sheha,Sorptionbehavior01'Zn(lI) ionson synthesizedhydroxyapatiles,JournalofColloidandInterfaceScience310(2007)18-26.[6] S. Babel, T.A. Kurniawan,Low-cost adsorbentsrol' heavy metals uptake fromcontaminatedwater:areview,JournalofHazardousMaterialsB97(2003)219-243.

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