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1、1,Reporter:ChenYuehaoMajor:EnvironmentalEngineeringResearchsupervisor:OuyangTong,Fabricationofnovelmagneticchitosangraftedwithgrapheneoxidetoenhanceadsorptionpropertiesformethylblue,2,Contents,Introduction,MaterialsandMethods,ResultsandDiscussion,Conclusions,3,FirstPart,4,MethylBlue(1/4),DyeWastewat
2、er,MethylBlue,5,Chitosan(2/5),Chitosan,Chitosanisalinearpolysaccharide,whichismadebydeacetylationofchitin.Andithasanumberofcommercialandpossiblebiomedicalapplicationsduetoitsbiodegradability,biocompatibilityandrenewability.,6,MagneticChitosan(3/5),Itisdifculttobeseparatedandrecoveredexceptbyhighspee
3、dcentrifugationandlter.,powderychitosan,MagneticChitosan(MC):attacheschitosantothesurfaceofmagneticparticles.,7,Grapheneoxide(4/5),Grapheneoxidehastheadvantagesoflargetheoreticalsurfacearea,highmechanicalstrength,richfunctionalgroups,non-toxicandinexpensive.,grapheneoxide,8,Experimentalobjectives(5/
4、5),(1)Exploreandpreparemagneticchitosan-grapheneoxide(MCGO)compositebio-adsorbentwithhigheradsorptioncapacityandexcellentseparationproperties.(2)Methylblue(MB)withlargeandcomplicatedstructureswasselectedasmodelpollutanttoevaluatedtheadsorptioncharacteristicsofMCGOunderlaboratoryconditions.,9,SecondP
5、art,10,PreparationofMCandMCGO(1/3),FeCl24H2OandFeCl36H2Oareusedtomakemagneticparticles.,Addmagneticparticlesandglutaraldehydetochitosanaceticacidsolution.,WashtheprecipitateuntilpHwasabout7,anddryit.,UsethemodiedHummersmethodtoprepareGO,andactivatethecarboxylgroupsofGO,MC,Add0.1gMCtotheactivatedGOso
6、lution.Afterultrasonicdispersionfor10min,themixedsolutionwasstirredfor2h.,MCGO,WashtheprecipitateuntilpHwasabout7,anddryit,11,Adsorptionexperiments(2/3),(1)AllbatchadsorptionexperimentswereperformedonaSHA-Cshakerwithashakerspeedof150rpmuntilthesystemreachedequilibrium.,(2)Typically,a25mLsolutionofkn
7、ownMBconcentrationand0.015gofMCGOwereaddedinto100mLglassasksandthenshookunder300.2.,(3)Atthecompletionofpresettimeintervals,thebio-adsorbentswerecollectedbytheaidofamagnet.,12,Adsorptionexperiments(3/3),ResidualMBconcentrationinsupernatantwasmeasuredbyusingaspectrophotometer.TheAbsorbanceismaxMB=610
8、nm.,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
9、.,TheMCGOhasamuchroughersurface,revealingthatmanysmallmagneticchitosanhadbeenassembledonthesurfaceofGOlayerswithahighdensity.,TheBETsurfacearea:392.5m2/g;Theporevolume:0.3852cm3/g;Theaverageoftheporesizedistributionis2.587nm.Theaverageparticlesizeis200nm.,mesoporousmaterial,15,FTIR(2/10),Fig.2.IRspe
10、ctraofGO(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),whichhasmagneticpropertiesand
11、canbeusedforthemagneticseparation.,17,pH(4/10),Fig.4.EffectofpHontheadsorptioncapacity(initialconcentration,200mg/L;temperature,303K;contacttime,60min).Blackpoints:QeversusinitialpHvalues;redpoints:equilibriumpHvaluesversusinitialpHvalues.,TheoptimumpHrangeforMBadsorptionontoMCGObio-adsorbentsis4.56
12、.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-orderkineticplotsfortheadso
13、rptionofMB(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).,Theadsorptionprocessismainlymonolayeradsorptiononthesu
14、rface.,TheLangmuiradsorptionisothermmodel,21,Temperature(8/10),Fig.7.VantHoffplotsfortheadsorptionofMBontoMCGO,ThenegativevalueofHshowsexothermicnatureofadsorptionprocess.TheadsorptionwasfavoredatlowertemperatureandMBmoleculeswereorderlyadsorbedonthesurfaceofMCGO.ThenegativevalueofGindicatesthatthea
15、dsorptionreactionwasspontaneousat303,313and323K.,Table2Thermodynamicparametersatdifferenttemperatures.,VantHoffequation,22,Desorptionexperiments(9/10),Fig.8.EffectofrecyclingadsorbentsonMBadsorption(pH,5.3;initialconcentration,200mg/L;temperature,303K;contacttime,60min).,The0.5mol/LNaOHistheoptimume
16、luent.,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