CoMnAl层状双氢氧化物催化臭氧氧化水中有机污染物的活性英文

2012ChineseJournalofCatalysisVol.33No.8文章编号:0253-9837(2012)08-1284-06国际版DOI:10.1016/S1872-2067(11)60392-6研究论文:1284~1289Co-Mn-Al层状双氢氧化物催化臭氧氧化水中有机污染物的活性隋铭皓*,段标标,盛力,黄书杭,佘磊同济大学环境科学与工程学院污染控制与资源化国家重点实验室,上海200092摘要:采用共沉淀法制备了Co-Mn-Al层状双氢氧化物,并将其用于以硝基苯为目标污染物的催化臭氧降解反应中.结果表明,Co-Mn-Al层状双氢氧化物存在时,硝基苯的降解和矿化效率较单独臭氧氧化系统显著提高.采用加入羟基自由基捕获剂(叔丁醇)和电子顺磁共振检测(5,5-二甲基-1-吡咯啉-N-氧化物为捕获剂)的间接、直接方法,探讨了Co-Mn-Al层状双氢氧化物是否强化了羟基自由基的生成.结果表明,加入叔丁醇降低了硝基苯的降解效率;电子顺磁共振检出了更强的羟基自由基加成物生成信号.Co-Mn-Al层状双氢氧化物的存在促进了羟基自由基的生成.关键词:层状双氢氧化物;催化臭氧;硝基苯;叔丁醇,电子顺磁共振;羟基自由基中图分类号:O643文献标识码:A收稿日期:2012-03-14.接受日期:2012-04-09.*通讯联系人.电话:[phone];传真:[phone];电子信箱:[e-mail]基金来源:国家自然科学基金(50708067,51078281);百篇优秀博士论文(2007B48);中央高校基本科研业务费专项资金(0400219192).本文的英文电子版(国际版)由Elsevier出版社在ScienceDirect上出版().CatalyticPerformanceofLayeredDoubleHydroxidesCo-Mn-AlforOzonationofOrganicPollutantsinWaterSUIMinghao*,DUANBiaobiao,SHENGLi,HUANGShuhang,SHELeiStateKeyLaboratoryofPollutionControlandResourceReuse,SchoolofEnvironmentalScienceandEngineering,TongjiUniversity,Shanghai200092,ChinaAbstract:ThecatalyticactivityoflayereddoublehydroxidescontainingCo,Mn,andAlfortheozonationoforganicpollutantsinwaterwasinvestigated.TheCo-Mn-Allayereddoublehydroxideswerepreparedbycoprecipitation.Nitrobenzenewasusedasamodelcompound,anditwasshownthatthedegradationandmineralizationofnitrobenzenewasincreasedbythepresenceofCo-Mn-Allayereddoublehydroxidesascomparedtoozonationalone.Bothanindirectmethodofaddingascavenger(tert-butanol)ofthehydroxylradicalchainreactionanddirectelectronspinresonanceusing5,5-dimethyl-1-pyrroline-N-oxideasaspintrappingagentwereusedtoinvestigatethegenerationofhydroxylradicalsintheozonationbytheCo-Mn-Allayereddoublehydroxides.Theinhibitingeffectoftert-butanolonthedegradationofnitrobenzeneandthedetectionofthestronger5,5-dimethyl-1-pyrroline-N-oxide/hydroxylradicaladductshowedthattheCo-Mn-Allayereddoublehydroxidescatalyzedthegenerationofhydroxylradicals.Keywords:layereddoublehydroxide;catalyticozonation;nitrobenzene;tert-butanol;electronspinresonance;hydroxylradicalReceived14March2012.Accepted9April2012.*Correspondingauthor.Tel:[phone];Fax:[phone];E-mail:[e-mail]ytheNationalNaturalScienceFoundationofChina(50708067,51078281),FoundationfortheAuthoroftheNationalExcellentDoctoralDissertationofChina(2007B48),andFundamentalResearchFundsfortheCentralUniversities(0400219192).EnglisheditionavailableonlineatElsevierScienceDirect().Heterogeneouscatalyticozonationisanefficienttech-nologytoremoveorganicpollutantsinaqueoussolutions[1,2].Thekeytohighdegradationeffectivenessistohavehighlyactivecatalysts.Transitionmetalsarecommonlyappliedascatalystsinozonationbecausetheyhavevariableoxidationstates[3–5].Theeffectivenessoftheheterogene-隋铭皓等:Co-Mn-Al层状双氢氧化物催化臭氧氧化水中有机污染物的活性1285ouscatalyticozonationprocessisoftenascribedtothegen-erationofhydroxylradicals(•OH),whicharestrongoxida-tivespeciesthatreactnon-selectivelywithcompounds[6].Layereddoublehydroxides(LDHs)havereceivedin-creasingattentioninrecentyears.Theyhavebeenusedinenvironmentalremediationasadsorbents,catalysts,andcatalystsupports[7–9].ThegeneralformulaoftheLDHsis[MⅡ1-xMⅢx(OH)2]x+[An–x/n]·H2O,whereMⅡrepresentsadivalentmetal,MⅢatrivalentmetal,andAn–ananion.ThemanychoicesforMⅡandMⅢ,especiallyfromthetransitionmetals,andthehydroxylgroupsinthelayerstructuregivetheLDHmaterialshighcatalyticactivitytowardsozone[1].Furthermore,theOH–groupsbehaveasaweakbasethatcanalsoactivateozonetodecomposeintohydroxylradicals[10].However,therehasbeennoinvestigationofthecata-lyticactivityofLDHsinozonation.Inthepresentstudy,thecatalyticactivityofLDHscon-tainingcobaltandmanganesecationsonozonationwasinvestigatedusingnitrobenzene(NB)asamodelorganicpollutant.NBisresistanttooxidationbyozonealonebe-causeofthestrongelectron-withdrawingpropertyofthenitrogroup[11].Bothcobaltandmanganesehaveshowncatalyticactivitywithozonefortheremovaloforganicpol-lutantsinaqueoussolution[12–14].Thusacatalystthatcombinescobaltandmanganeseinacompositematerialisalsoexpectedtohavegoodcatalyticactivitywithozone.1Experimental1.1CatalystpreparationandcharacterizationThecatalystswerepreparedbythecoprecipitationmethod[15].Thesamplesaredenotedbytheirelementalcompositionsandmolarratiosoftheconstituents.Thefol-lowingsampleswereprepared:Co4Al2,Co4MnAl,andCo4Mn2.Forexample,Co4MnAlisasamplecontainingCo,Mn,andAlinthemolarratioof4:1:1.Thedetailedpreparationprocedureisasfollows.Nitratesolution(250ml)comprisingCo(NO3)2·6H2O,Mn(NO3)2·4H2O,andAl(NO3)3·9H2OwiththeCo/(Mn+Al)molarratioequalto2andatotalmetalionconcentrationof1.0mol/Lwasaddedwithaflowrateof5.0ml/minintoamixedflowre-actor.Simultaneously,alkalinesolutionsof0.5mol/LNa2CO3and3.0mol/LNaOHwereaddedatavariableflowratetokeepthereactionpHat10.0±0.1.Thecoprecipita-tionwascarriedoutat25°Cundervigorousstirringfor2h.Theresultingsuspensionwascentrifugedandtheproductwasfilteredoffandrepeatedlywashed,a