1,Reporter:ChenYuehaoMajor:EnvironmentalEngineeringResearchsupervisor:OuyangTong,Fabricationofnovelmagneticchitosangraftedwithgrapheneoxidetoenhanceadsorptionpropertiesformethylblue,2,Contents,Introduction,MaterialsandMethods,ResultsandDiscussion,Conclusions,3,FirstPart,4,MethylBlue（1/4）,DyeWastewater,MethylBlue,5,Chitosan（2/5）,Chitosan,Chitosanisalinearpolysaccharide,whichismadebydeacetylationofchitin.Andithasanumberofcommercialandpossiblebiomedicalapplicationsduetoitsbiodegradability,biocompatibilityandrenewability.,6,MagneticChitosan（3/5）,Itisdifculttobeseparatedandrecoveredexceptbyhighspeedcentrifugationandlter.,powderychitosan,MagneticChitosan(MC):attacheschitosantothesurfaceofmagneticparticles.,7,Grapheneoxide（4/5）,Grapheneoxidehastheadvantagesoflargetheoreticalsurfacearea,highmechanicalstrength,richfunctionalgroups,non-toxicandinexpensive.,grapheneoxide,8,Experimentalobjectives（5/5）,（1）Exploreandpreparemagneticchitosan-grapheneoxide(MCGO)compositebio-adsorbentwithhigheradsorptioncapacityandexcellentseparationproperties.（2）Methylblue(MB)withlargeandcomplicatedstructureswasselectedasmodelpollutanttoevaluatedtheadsorptioncharacteristicsofMCGOunderlaboratoryconditions.,9,SecondPart,10,PreparationofMCandMCGO（1/3）,FeCl24H2OandFeCl36H2Oareusedtomakemagneticparticles.,Addmagneticparticlesandglutaraldehydetochitosanaceticacidsolution.,WashtheprecipitateuntilpHwasabout7,anddryit.,UsethemodiedHummersmethodtoprepareGO,andactivatethecarboxylgroupsofGO,MC,Add0.1gMCtotheactivatedGOsolution.Afterultrasonicdispersionfor10min,themixedsolutionwasstirredfor2h.,MCGO,WashtheprecipitateuntilpHwasabout7,anddryit,11,Adsorptionexperiments（2/3）,（1）AllbatchadsorptionexperimentswereperformedonaSHA-Cshakerwithashakerspeedof150rpmuntilthesystemreachedequilibrium.,（2）Typically,a25mLsolutionofknownMBconcentrationand0.015gofMCGOwereaddedinto100mLglassasksandthenshookunder300.2.,（3）Atthecompletionofpresettimeintervals,thebio-adsorbentswerecollectedbytheaidofamagnet.,12,Adsorptionexperiments（3/3）,ResidualMBconcentrationinsupernatantwasmeasuredbyusingaspectrophotometer.TheAbsorbanceismaxMB=610nm.,Q:adsorptionquantity;E:adsorptionrate;C0:theinitialconcentration;Ce:theequilibriumconcentration;V:thevolumeofMBsolution,inliters;W:theweightoftheMCGOused,ingrams.,13,ThirdPart,14,SEM（1/10）,Fig.1.SEMimagesofGO(A)andMCGO(B).,GO：thesheet-likestructurewithlargethickness,smoothsurface,andwrinklededge.,TheMCGOhasamuchroughersurface,revealingthatmanysmallmagneticchitosanhadbeenassembledonthesurfaceofGOlayerswithahighdensity.,TheBETsurfacearea:392.5m2/g;Theporevolume:0.3852cm3/g;Theaverageoftheporesizedistributionis2.587nm.Theaverageparticlesizeis200nm.,mesoporousmaterial,15,FTIR（2/10）,Fig.2.IRspectraofGO(A)andMCGO(B).,C-O-C,C-OH,C-C,C-O(COOH),O-H,Fe3O4,C-O(NHCO),16,XRD（3/10）,Fig.3.XRDpatternofpureFe3O4(A),magneticchitosan(B)andMCGO(C).,TheXRDanalysisresultsofpureFe3O4,magneticchitosanandMCGOweremostlycoincident.Itindicatestheexistenceofironoxideparticles(Fe3O4),whichhasmagneticpropertiesandcanbeusedforthemagneticseparation.,17,pH（4/10）,Fig.4.EffectofpHontheadsorptioncapacity(initialconcentration,200mg/L;temperature,303K;contacttime,60min).Blackpoints:QeversusinitialpHvalues;redpoints:equilibriumpHvaluesversusinitialpHvalues.,TheoptimumpHrangeforMBadsorptionontoMCGObio-adsorbentsis4.56.5.,18,Adsorptionkinetics（5/10）,Thepseudo-rst-orderkineticmodel,Qe:adsorptionquantityatequilibrium,inmg/g;Qt:adsorptionquantityattimet,inmg/g;K1:therateconstantofadsorption(min1);t:time,inmin.,Thepseudo-second-orderkineticmodel,19,Adsorptionkinetics（6/10）,Fig.5.Pseudo-rst-orderkineticplotsfortheadsorptionofMB(A),andpseudo-second-orderkineticsforadsorptionofMB(B)(pH5.3,temperature:303K).,Table1AdsorptionkineticparametersofMBontoMCGO.,20,Adsorptionisotherm（7/10）,Fig.6.ThelineardependenceofCe/QeonCe(pH,5.3;temperature,303K;contacttime,60min).,Theadsorptionprocessismainlymonolayeradsorptiononthesurface.,TheLangmuiradsorptionisothermmodel,21,Temperature（8/10）,Fig.7.VantHoffplotsfortheadsorptionofMBontoMCGO,ThenegativevalueofHshowsexothermicnatureofadsorptionprocess.TheadsorptionwasfavoredatlowertemperatureandMBmoleculeswereorderlyadsorbedonthesurfaceofMCGO.ThenegativevalueofGindicatesthattheadsorptionreactionwasspontaneousat303,313and323K.,Table2Thermodynamicparametersatdifferenttemperatures.,VantHoffequation,22,Desorptionexperiments（9/10）,Fig.8.EffectofrecyclingadsorbentsonMBadsorption(pH,5.3;initialconcentration,200mg/L;temperature,303K;contacttime,60min).,The0.5mol/LNaOHistheoptimumeluent.,Table3ThedesorptionpercentagesofHCl,NaOHandH2O(Concentration,0.5mol/L).,23,最大吸附量（10/10）,Table4MaximumadsorptioncapacitiesfortheadsorptionofMBontovariousadsorbents.,24,Fourthpart,25,Conclusions（1/1）,（1）PreparetheMCGOcompositebio-adsorbentwithhigheradsorptioncapacityandexcellentseparationpropertiessuccessfully.（2）TheadsorptionofMBonMCGOwasstronglydependonpHandionicstrength,indicatinganionexchangemechanism.（3）Theadsorptionfollowedpseudo-second-o