物理药剂学ppt

ColloidaldispersionsystemClassificationofdispersedsystembasedonparticlesizeclassParticlesizeCharacteristicsofsystemexampleMoleculardispersionLessthan1nmInvisibleinelectronmicroscopePassthroughultrafilterandsemipermeablemembraneundergorapiddiffusionOxygenmolecules,ordinaryions,glucoseColloidaldispersionFrom1nmtoo.5μmNotresolvedbyordinarymicroscope(althoughmaybedetectedunderultramicroscope)VisibleinelectronmicroscopePassthoughfilterpaperDonotpasssemipermeablemembraneDiffusionveryslowlyColloidalsilversols,naturalandsyntheticpolymers,cheese,butter,jelly,milk,etc.CoarsedispersionGreaterthano.5μmVisibleundermicroscopeDonotpassthoughnormalfilterpaperDonotdialyzethoughsemipermeablemenmbraneDonotdiffusionGrainsofsand,mostpharmaceuticalemulsionsandsuspension,redbloodcellsTypesofColloidaldispersionLyophiliccolloidsLyophobiccolloidsAssociationcolloidsLyophiliccolloidsSystemscontainingcolloidalparticlesthatinteracttoanappreiableextentwiththedispersionmediumarereferredtoaslyophilic(solvent-loving)colloids.hydrophilicsols:gelatin,acacia,insulin,albuminLipophiliccolloids:rubber,polystyrene.Amaterialthatformsalyophiliccolloidalsysteminoneliquid(e.g.water)maynotdosoinanotherliquid(e.g.benzene).LyophobiccolloidsLyophobiccolloidsiscomposedofmaterialsthathavelittleattraction.e.g.gold,silver,sulfur,arsenoussulfide,andsilveriodide.Themethodstopreparelyophobiccolloids•Dispersionmethods1,grindingmethod2,sonicationdispersionmethod3,arcdischargemethod•Condensationmethods1,physicalmethods2,chemicalmethodsgrindingmethodsonicationdispersionmethodarcdischargemethod•Owingtotheintenseheatgeneratedbythearc,someofthemetaloftheelectrodesisdispersedasvapor,whichcondensestoformcolloidalparticles.Physicalcondensationmethods1,replacementofsolventPhysicalcondensationmethods2,Steamquenchmethodchemicalcondensationmethods•2H3AsO3（w）+3H2S→As2S3（sol）+6H2O•FeCl3（w）+3H2O（H）→Fe(OH)3（sol）+3HCl•2H2S(w）+SO2(g)→2H2O+3S(sol）•Na2S2O3+2HCl→2NaCl+H2O+SO2+S(sol)•2HAuCl4+3HCHO+11KOH→2Au(sol）+3HCOOK+8KCl+8H2OSolpurification•1,dialysismethod•2,ultrafiltrationdialysismethod•Semipermeablemembranedialysismethod•Electrodialysisultrafiltration•Semipermeablemembraneultrafiltration•ElectroultrafiltrationAssociationcolloidsCMCthecriticalmicelleconcentration(CMC)isdefinedastheconcentrationofsurfactantsabovewhichmicellesformandalladditionalsurfactantsaddedtothesystemgotomicelles.Typeofmicelle•Cylindricalmicelle•Bilayer•Bilayervesicle•Invertedmicelle•MicrotubuleClassificationandtypicalexamplesofassociationcolloidsExampleTypeCompoundAmphiphileGegenionsAnionicSodiumlaurylsulfateCH3(CH2)11OSO3-Na+CationicCetyltrimethyl-ammoniumbromideCH3(CH2)15N+(CH3)3Br-NonionicPolyoxyethylenelauryetherCH3(CH2)10CH2O(CH2OCH2)23H—AmpholyticDimenthyldodecylammonio-propanesulfonateCH3(CH2)11N+(CH3)2(CH2)3OSO2-—Propertiesofsurface-activeagentsshowingchangesthatoccursharplyattheCMCPredicttheCMCofthemixture•1𝐶𝑀𝐶=𝑥1𝐶𝑀𝐶1+𝑥2𝐶𝑀𝐶2TodeterminetheminimumamountofsurfactantOpticalpropertiesofcolloidsscatteringoflightLightscatteringisaformofscatteringinwhichlightistheformofpropagatingenergywhichisscattered.Lightscatteringcanbethoughtofasthedeflectionofarayfromastraightpath,forexamplebyirregularitiesinthepropagationmedium,particles,orintheinterfacebetweentwomedia.TheFaraday-TyndallEffect•Whenastrongbeamoflightispassedthroughacolloidalsol,avisiblecone,resultingfromthescatteringoflightbythecolloidalparticles,isformed.ThisistheFaraday-tyndalleffect.Ultramicroscope•Anultramicroscopeisamicroscopewithasystemofilluminationthatallowsviewingoftinyparticles.Whenthediameterofaparticleisbelowornearthewavelengthofvisiblelight(around500nanometers),theparticlecannotbeseeninalightmicroscopewiththeusualmethodofillumination.Theultramicroscopesystemisbasedonlightscattering,notlightreflection.UltramicroscopeElectronmicroscopeElectronmicroscope,capableofyieldingpicturesoftheactualparticles,eventhoseapproachingmoleculardimensions,isnowwidelyusedtoobservethesize,shape,andstructureofcolloidalparticles.Kineticpropertiesofcolloids1,Thermallyinduced:Brownianmovement,diffusion,osmosis.2,gravitationallyinduced:sedimentation3,appliedexternally:viscosityBrownianMotion—therandommovementofcolloidalpartoclesThefirstsatisfactorytheoreticaltreatmentofBrownianmotionwasmadebyAlbertEinsteinin1905.DiffusionDeducedbyEinsteinandStrokes•WhereNAisAvogadro'snumber,Risthegasconstant,ηisthecoefficientofviscosityofthesurroundingmedium,ristheradiusofthesphericalparticle,Tistheabsolutetemperature•Diffusionisanentropyincreasingprocess.DiffusionOsmoticpressure𝜋=cRT𝜋=cg𝑀RT𝜋cg=𝑅𝑇𝑀𝜋cg=𝑅𝑇(1𝑀+𝐵cg)Sedimentation•Inagravitationalfield,heavyparticlessettletowardsthefootofacolumnofsolutionbytheprocesscalledsedimentation.•Whenasolutionisallowedtostand,astateofequilibriumisfinallyreachedwhensedimentationanddiffusionbalanceeachother,thatis,wheninagivenintervaloftimetheamountofmaterialwhichfallsinthedownwarddirectionthroughaunitareaisthesameasthatwhichdiffusesupwardbecauseofthegreaterconcentrationatthelowerlevel.sedimentationdiffusionultracentrifugationSed