秦淮八绝专业外语文献PPT.ppt

秦淮八绝专业外语文献PPT.ppt

《秦淮八绝专业外语文献PPT.ppt》由会员分享，可在线阅读，更多相关《秦淮八绝专业外语文献PPT.ppt（31页珍藏版）》请在冰豆网上搜索。

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