秦淮八绝专业外语文献PPT.ppt
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秦淮八绝专业外语文献PPT.ppt
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专业外语文献精读笔记(PPT版)学院:
电子科学与技术学专业:
光学工程学号:
091042姓名:
郭峰指导教师:
崔一平王著元ControlledSynthesisofMagnetite-SilicaNanocompositesviaaSeededSol-GelApproachaSeededSol-GelApproachmagneticnanoparticles,especiallyFe3O4and-Fe2O3,haveattractedincreasinginterestbecauseoftheiroutstandingpropertiesincludingsuperparamagnetismandlowtoxicityand,asaresult,theirpotentialapplicationsinvariousfields,especiallyinbiotechnologyandbiomedicine,suchascellsorting,enzymeimmobilization,biosensingandbioelectrocatalysis,separationandpurification,andsoon.1、IntroductionThesol-gelapproachprovedtobearobustwaytofabricatemagneticnanocomposites,becausethesurfaceofmagnetitehasstrongaffinitytowardsilica.ThesilicacoatingsonmagnetitenanoparticlesnotonlypreventmagneticnanoparticlesfromaggregationinwidepHrangesinaqueoussolutionbutalsoprovidethemwithasilica-likesurface,whichiseasilyfurthermodifiedwithvariousfunctionalitiestomeetvariouspracticalapplications.Thesilicacoatingsprovidemagnetitenanoparticleswithachemicallyinertsurface,whichisespeciallyimportantinbiologicalapplications.Surfacemodificationofmagnetitenanoparticlesisneededtoincreasetheirdispersingstabilityinreactionmediaduringthesilicacoatingprocess.2、ExperimentalsectionMaterials:
FeCl36H2O,FeCl24H2O,NaOH,trisodiumcitrate,TEOS,ethanol,ammoniaaqueous(25wt%),distilledwater.SynthesisandModificationofMagnetiteNanoparticles:
1、0.04molFeCl36H2O,0.02molFeCl24H2Oweredissolvedin150mLofdistilledwaterinathree-neckedbottom(250mL).Argonfor1h.2、Underrapidmechanicalstirring(600rpm),add20mLNaOH(10M)intothesolutionwithin30minusingadroppingfunnel.Stirringfor1h.3、Theresultantblackdispersionwasheatedto90Cfor1h.4、Coolingblackdispersiontotemperature.Sortthemagneticmudwithamagnet.Redispersitin200mltrisodiumcitratesolution(0.3M),heatedat80Cfor1h.5、Inexperiment,Themagneticfluidobtainedbytreatingtheas-mademagnetitewithatrisodiumcitratesolutionof0.1,0.3,and0.5MweredenotedasMF-1,MF-2andMF-3,respectively.CoatingMagnetiteNanoparticleswithSilica.1、Magneticfluid(2.0g)wasdilutedinwater(40mL),ethanol(120mL),andconcentratedaqueousammonia(3.0mL,28wt%).2、TEOSinethanol(20mL)wasdropwiseaddedtothisdispersion.Stirringfor12h.3、theobtainedproductwascollectedbymagneticseparationandwashedwithethanolfor3.Figure1.TEMimagesofmagnetitenanoparticles(a)beforeand(b)aftertreatedwithtrisodiumcitratesolution(0.3M).Theinsetsinpartsaandbshowtheselectiveareaelectrondiffractionpatternofthemagnetitenanoparticlesandthemagneticresponsivenessofthemagneticfluidtotheappliedmagnet(2000Oe),respectively.3、ResultsandDiscussionFigureS1.X-raydiffractionpatternsoftheas-mademagnetitenanoparticles.Twonewabsorptionpeaksat1619and1395cm-1appearin(Figure2b),whicharecharacteristicofthecarboxylate.Itverifiedthecomplexationbetweenthecitrategroupsandironionsonthemagnetitenanoparticlessurface.1、Aftertreatmentwithtrisodiumcitrate,allofthemagnetitenanoparticlesamples,includingMF-1,MF-2,andMF-3,werehighlynegativelychargedintherangeofpH=5-11.2、Astrisodiumcitrateincrease,thepotentialoftheMF-1,MF-2,MF-3samplesprogressivelyincreasesfrom-63.3,to-70.8andto-79.2mVatpH9inthephosphatebuffersolution.Itsuggeststhatcitratetreatmentcancontinuouslyimpartmagnetitenanoparticleswithnegativechargesandthusincreasetheirdispersibilityinaqueoussolution.70nm150nmFigure5.Reactionmechanismsbetweenmagnetitenanoparticlesandcitrategroupsandtheformationofmagneticsilicaparticleswithvariousstructures.1、ThethicknessofsilicashelloftheFe3O4SiO2particlescanbeconvenientlyadjustedbycontrollingtheadditionamountofsilicasource(TEOS).Figure6.TEMimagesofcore-shellmagneticsilicamicrospheresobtainedusingMF-3astheseedanddifferentadditionalamountoftheTEOS(a)0.9g,(b)1.8g,and(c)4.5g.2、Thesilicathicknessdramaticallyincreasefrom24.5to36.0andto56.0nm,respectively.Figure7.SEMimagesofcore-shellmagneticsilicamicrospheresobtainedusingMF-3astheseedanddifferentadditionamountoftheTEOS(a)0.9g,(b)1.8g,(c)4.5g,and(d)plotofthediameterofmagneticsilicamicrospheresusingMF-3astheseedvstheadditionamountofTEOS.Theinsetinpartdshowsphotographicimagesoftheaqueousdispersionofthecore-shellmagneticsilicacompositeparticlesobtainedusingMF-3astheseedsanddifferentadditionalamountsofTEOS.Forcomparison,MF-3aqueousdispersionandcolloidalsilicadispersionarealsodisplayed.FigureS2.X-raydiffractionpatternsofthemagneticsilicacompositeobtainedusingMF-3astheseedsand1.8gofTEOS.FigureS3.ThehysteresisloopsofthemagneticsilicacompositeparticlesobtainedbyusingMF-3astheseeds
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