Utilizationofgroundeggshellwasteasanadsorbentforth

Assessmentoftheadsorptionkinetics,equilibriumandthermodynamicforthepotentialremovalofreactivereddyeusingeggshellbiocompositebeadsM.F.Elkadya,AmalM.Ibrahimb,M.M.AbdEl-Latifa,⁎aFabricationTechnologyDepartment,AdvancedTechnologyandNewMaterialsResearchInstitute(ATNMRI),CityforScientificResearchandTechnologyApplications(CSAT),Previously“MubarakCityforScientificResearchandTechnologyApplications(MuCSAT)”Alexandria,EgyptbSurfaceChemistryandCatalysisLaboratory,PhysicalChemistryDepartment,NationalResearchCenter,AlBuhouthSt.,Cairo,EgyptabstractarticleinfoArticlehistory:Received6February2011Receivedinrevisedform21May2011Accepted25May2011Availableonline15June2011Keywords:C.I.RemazolReactiveRed198EggshellbiocompositeImmobilizationAdsorptionkineticsEquilibriumisothermsBiosorptionWastewatertreatmentImmobilizedeggshellwithapolymermixtureofalginateandpolyvinylalcoholwasappliedasabiocompositeadsorbent(ESC)fortheadsorptionofC.I.RemazolReactiveRed198fromaqueoussolution.ESCwascharacterizedusingXRD,TGA,FTIRandSEM.TheReddyeadsorptionontotheESCwasinvestigatedinabatchsystemwithrespecttoinitialdyeconcentration,pH,contacttime,agitationspeed,solutiontemperatureandbiocompositedosage.Thepreparedbiocompositeexhibitshighefficiencyforreddyeadsorptionandtheequilibriumstatescouldbeachievedin3hforthedifferentstudiedinitialdyeconcentrations.TheequilibriumisothermstudyindicatedthatsorptiondatawereanalyzedandfittedwellbybothLangmuirandTemkinmodelscomparedtoFreundlichmodel.Themaximummonolayerdyeadsorptioncapacity(attheoptimumpH1.0)wasestimatedtobe46.9mg/gat22°C.Thekineticstudyrevealedthatpseudo-secondordermodelfittedwellthekineticdata,whileboththeintraparticlediffusionandBoydkineticmodelindicatedthatintraparticlediffusionwasthemainratedeterminingstepinthebiosorptionprocess.Thenegativevaluesofboththeenthalpy(ΔH°)andGibbsfreeenergy(ΔG°)changesindicateexothermicaswellasfeasibleandspontaneousnatureofthebiosorptionprocessrespectively.©2011ElsevierB.V.Allrightsreserved.1.IntroductionSyntheticdyesexhibitconsiderablestructuraldiversity,whichincludingarylringsthathavedelocalizedelectronsystem.Dyesareorganiccompoundsconsistingoftwomaingroupsofcompounds,chromophores(responsibleforcolorofthedye)andauxochromes(responsibleforintensityofthecolor)[1].Thechromophoregroupisaradicalconfigurationconsistingofconjugateddoublebondscontain-ingdelocalizedelectrons.Thechromogen,whichisthearomaticstructurenormallycontainingbenzene,naphthaleneoranthracenerings,isapartofchromogen–chromophorestructurealongwithanauxachrome.Thepresenceofionizinggroupsknownasauxochromesresultsinamuchstrongeralternationofthemaximumabsorptionofthecompoundandprovidesabondingaffinity[2].Somecommonauxochromegroupsinclude―NH3,―COOH,―HSO3,―OH[3].Coloreddyewastewaterarisesasadirectresultoftheproductionofdyeandalsoasaconsequenceofitsuseindifferentindustries.AccordingtotheColorIndex(C.I.),whichismanagedbytheSocietyofDyersandColoristsandtheAmericanAssociationofTextileChemistsandColorists,currentlymorethan10,000varioustypesofdyesaresynthesizedandavailableintheworld.Althoughnorecentdataisavailableonworldwidedyeproduction,annualproductionofover700,000toneshasbeenoftenreportedintheliterature[4–6].Syntheticdyesareextensivelyusedinmanyfieldsofupto-datetechnology,e.g.,invariousbranchesofthetextileindustry[7,8],oftheleathertanningindustry[9]inpaperproduction[10],infoodtechnology[11],inagriculturalresearch[12],inlight-harvestingarrays[13],inphotoelectrochemicalcells[14]andinhaircolorings[15].Moreover,syntheticdyeshavebeenemployedforthecontroloftheefficiencyofsewage[16]andwastewatertreatment[17],forthedeterminationofspecificsurfaceareaofactivatedsludge[18]forgroundwatertracing[19],etc.Duetothegoodsolubilityofthesyntheticdyes,theyarecommonwaterpollutantsandtheymayfrequentlybefoundintracequantitiesinindustrialwastewater.Anindicationofthescaleoftheproblemisgivenbythefactthat2%ofdyesproducedannuallyaredischargedineffluentfrommanufacturingoperations,while10%wasdischargedfromtextileandassociatedindustries[20].Largequantitiesofreactivedyesareutilizedbythetextileindustry.Therapidgrowthrateintheuseofreactivedyesisduetotheincreasinguseofcellulosicfibersandthetechnicalandeconomicallimitationsofotherdyesusedforthesefibers[21,22].Sincedyesarestable,recalcitrant,colorant,andevenpotentiallycarcinogenicandtoxic[23,24],theirreleaseintotheenvironmentposesseriousenvironmental,aestheticalandhealthproblems.Thus,industrialdye-ladeneffluentsareanincreasinglymajorconcernandDesalination278(2011)412–423⁎Correspondingauthor.Tel./fax:[phone].E-mailaddresses:[e-mail](M.F.Elkady),[e-mail](A.M.Ibrahim),[e-mail](M.M.A.El-Latif).0011-9164/$–seefrontmatter©2011ElsevierB.V.Allrightsreserved.doi:10.1016/j.desal.2011.05.063ContentslistsavailableatScienceDirectDesalinationjournalhomepage: