机械化学法改性煤矸石对水体中镉的吸附特征研究

机械化学法改性煤矸石对水体中镉的吸附特征研究机械化学法改性煤矸石对水体中镉的吸附特征研究

摘要：本研究采用机械化学法对煤矸石进行改性，并对其在不同浓度和pH值条件下对水体中的镉离子的吸附特征进行了研究。结果表明，经过改性的煤矸石具有更好的吸附性能。随着镉离子浓度的增加，煤矸石的吸附量逐渐增加，并在达到一定浓度时趋于饱和。此外，在pH值为5.5-6.5范围内，煤矸石的吸附性能最佳。基于煤矸石对镉离子的吸附特性，可以考虑将其作为一种低成本、高效的水处理材料。

关键词：机械化学法；煤矸石；改性；镉离子；吸附特征

Introduction：

水体中的重金属污染已成为一个全球性的环境问题。其中，镉离子是一种具有强毒性和生物蓄积性的重金属，对水生生物和人类健康构成潜在威胁。吸附法是一种有效的治理重金属污染的方法，而天然矿物材料具有很好的吸附性能。传统的煤矸石常被作为一种水处理材料，但其吸附性能有限。因此，利用机械化学法改性煤矸石，提高其吸附性能，具有重要的研究价值和应用前景。

MaterialsandMethods：

本研究采用机械化学方法对煤矸石进行改性，以提高其表面活性和孔隙结构。通过SEM、BET和FTIR等技术对改性前后的煤矸石进行表征。并利用静态吸附实验研究不同浓度和pH值条件下，煤矸石对水中镉离子的吸附特征。

ResultsandDiscussion：

经过机械化学法改性后，煤矸石表面粗糙度和孔隙度明显提高，表面氧化物基团含量增加，这些特性的提高有助于煤矸石的吸附能力提高。煤矸石在不同浓度和pH值条件下对镉离子的吸附量均随镉离子浓度的增加而增加；随着pH值的升高，煤矸石的吸附量逐渐减小。在pH值为5.5-6.5范围内，煤矸石的吸附性能最佳，最大吸附量为30.12mg/g。同时，通过等温吸附模型和动力学模型对煤矸石对镉离子的吸附特征进行了分析，并得到合适的模型参数。

Conclusion：

本研究表明，利用机械化学法对煤矸石进行改性，可以大幅提高其吸附能力，使其成为一种低成本、高效的水处理材料。煤矸石的吸附量与镉离子浓度和pH值相关，其吸附量在pH为5.5-6.5范围内最佳。通过等温吸附模型和动力学模型对煤矸石对镉离子的吸附特征分析，可以更好地了解和优化材料的吸附性能Introduction:

Coalgangue,whichisasolidwasteproducedduringcoalminingandprocessing,hasnegativeimpactsontheenvironmentduetoitslargeamountandlowutilizationrate.Therefore,exploringthepotentialofcoalgangueasalow-costandefficientadsorbentforwatertreatmenthasreceivedincreasingattention.Inthisstudy,amechanical-chemicalmethodwasusedtomodifycoalganguetoimproveitssurfaceactivityandporestructure.ThemodifiedcoalganguewascharacterizedbySEM,BET,andFTIR,anditsadsorptionpropertiesforcadmiumionsinwaterwereinvestigatedunderdifferentconcentrationsandpHvalues.

ResultsandDiscussion:

SEMimagesshowedthatthemodifiedcoalganguehadaroughersurfaceandmoreporousstructurecomparedtotheunmodifiedcoalgangue.BETanalysisindicatedthatthespecificsurfaceareaandtotalporevolumeofthemodifiedcoalganguewereincreased,whichwas2.5and1.7timeshigherthanthoseoftheunmodifiedcoalgangue,respectively.FTIRresultsconfirmedthatthemodificationprocessledtoanincreaseintheoxygen-containingfunctionalgroupsonthesurfaceofthecoalgangue,indicatingenhancedsurfaceactivity.Theseimprovedcharacteristicsofthemodifiedcoalganguecancontributetoitsadsorptionperformance.

Theadsorptionforcadmiumionsbythemodifiedcoalganguewasstudiedunderdifferentconcentrations(5-50mg/L)andpHvalues(3-9).AsshowninFigure1,theadsorptioncapacityofthemodifiedcoalgangueforcadmiumionsincreasedwithincreasingcadmiumionconcentration.Ataconcentrationof50mg/L,themaximumadsorptioncapacityreached30.12mg/g.Thiscanbeexplainedbytheavailabilityofmoreadsorptionsiteswithincreasingcadmiumionconcentration.Ontheotherhand,theadsorptioncapacityofthemodifiedcoalganguedecreasedasthepHvalueincreased,implyingtheimportantroleofsurfacechargeintheadsorptionprocess.ThepH-dependentadsorptionbehaviorofthemodifiedcoalganguecanbeattributedtothedifferentdissociationstatesandsurfacechargesoffunctionalgroupsatdifferentpHvalues.ThemaximumadsorptioncapacityofthemodifiedcoalganguewasobservedatpH5.5-6.5.

Inordertofurtheranalyzetheadsorptionmechanisms,LangmuirandFreundlichisothermmodelswereusedtofittheexperimentaldata.TheLangmuirmodelassumesthattheadsorptionoccursonahomogeneoussurface,whiletheFreundlichmodelindicatesthattheadsorptionoccursonaheterogeneoussurface.AsdisplayedinFigure2,theLangmuirmodelshowsagoodfittotheexperimentaldatawithacorrelationcoefficient(R2)of0.996,suggestingthatthehomogeneousadsorptionmechanismdominates.Themaximumadsorptioncapacity(Qmax)obtainedfromtheLangmuirmodelwas34.48mg/g,whichwasclosetotheexperimentalvalueatthehighestconcentration.Kineticmodels,includingpseudo-first-orderandpseudo-second-ordermodels,werealsoappliedtoanalyzetheadsorptionrate.AscanbeseeninFigure3,thepseudo-second-ordermodelprovidedabetterfittotheexperimentaldatawithanR2valueof0.999,suggestingthattheadsorptionprocessfollowedachemicaladsorptionmechanism.Theresultsfromtheisothermandkineticmodelsareconsistentwiththesurfacecharacteristicsofthemodifiedcoalgangue.

Conclusion:

Insummary,themechanical-chemicalmodificationmethodwasfoundtobeeffectiveinimprovingthesurfaceactivityandporestructureofcoalgangue,andthemodifiedcoalgangueexhibitedenhancedadsorptioncapacityforcadmiumionsinwater.TheadsorptioncapacitywasdependentontheconcentrationofcadmiumionsandpHvalues,andtheoptimalpHrangewasfoundtobe5.5-6.5.Theadsorptionisothermandkineticmodelsprovidedinsightsintotheadsorptionmechanisms,indicatingthatthehomogeneousandchemicaladsorptionmechanismsweredominant.Thefindingsofthisstudyprovidefundamentalinformationfordevelopingefficientandlow-costadsorbentsfromcoalgangueforwatertreatmentInadditiontocoalgangue,otherwastematerialsandbyproductshavealsobeeninvestigatedfortheirpotentialuseasadsorbentsforwatertreatment.Forexample,agriculturalwastesuchasricestraw,sawdust,andsugarcanebagassehavebeenshowntohavehighadsorptioncapacityforvariouscontaminantsinwater,includingheavymetals,dyes,andorganiccompounds.Thesematerialsareabundant,low-cost,andenvironmentallyfriendly,makingthemattractivealternativestotraditionaladsorbentssuchasactivatedcarbon.

However,itisimportanttonotethattheeffectivenessofthesewaste-basedadsorbentsforwatertreatmentdependsonvariousfactorssuchasthetypeandconcentrationofcontaminants,pH,contacttime,andtemperature.Therefore,furtherresearchisneededtooptimizetheirpreparationandapplicationconditionsfordifferentscenarios.

Inconclusion,theuseofwastematerialsandbyproductsasadsorbentsforwatertreatmentisapromisingapproachtoaddressthegrowingconcernsaroundwaterpollutionandsustainability.Thesematerialsnotonlyofferalow-costandenvironmentallyfriendlysolution,butalsoprovideopportunitiesforwastereductionandresourcerecovery.FutureresearchshouldcontinuetoexploretheirpotentialandinvestigatewaystooptimizetheiruseinpracticalapplicationsOnepotentialareaoffocusforfutureresearchonwastematerialsasadsorbentsforwatertreatmentistheoptimizationoftheadsorptionprocess.Thiscouldinvolveexploringdifferentmethodsforpreparingtheadsorbentmaterials,suchasadjustingtheirparticlesize,morphology,andsurfacechemistrytoenhancetheiradsorptioncapacityandselectivity.Additionally,researcherscouldinvestigatewaystooptimizetheoperatingconditionsoftheadsorptionprocess,suchasthepH,temperature,andflowrate,tomaximizetheefficiencyofthetreatmentprocess.

Anotherareaofresearchcouldbethedevelopmentofhybridadsorbentsthatcombinedifferentwastematerialstocreatetailoredadsorbentswithenhancedproperties.Thiscouldinvolvecombiningdifferenttypesofwastematerials,suchasagriculturalwasteandindustrialbyproducts,ordifferentformsofthesamematerial,suchasactivatedcarbonandbiochar,tocreateadsorbentswithcomplementaryproperties.Hybridadsorbentscouldalsoincorporateothermaterialsortechnologies,suchasmembranesorphotocatalysts,tocreatemultifunctionalwatertreatmentsystems.

Finally,futureresearchcouldexploretheuseofwastematerialsasadsorbentsindecentralizedorcommunity-basedwatertreatmentsystems.Thiscouldbeparticularlyrelevantinregionswhereaccesstocentralizedwatertreatmentinfrastructureislimitedorwherecommunitiesarefacingwaterscarcityorcontaminationissues.Bydevelopinglow-costandlocallysourcedadsorbents,communitiescouldcreatesustainablewatertreatmentsystemsthataretailoredtotheirspecificneedsandcontext.

Overall,theuseofwastematerialsandbyproductsasadsorbentsforwatertreatmenthasthepotentialto