(洗涤作用).ppt

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1、Chapter9.DetergencyofSurfactants2006.6.6.§1.IntroductionCleaningprocessisaverycomplexprocess;Nosurfactantsbyselfcancleanasurface;Detergency(洗涤作用)–thisterm,whenappliedtoasurfactants,meansthespecialpropertyithasofenhancingthecleaningpowerofaliquid.Detergency–acombinationofeffectsinvolvingadsor

2、ptionatinterface,alterationofinterfacialtension,solubilization,emulsification,andtheformationanddissipationofsurfacecharges;Detergency–involvingmechanicalaction,biochemicalaction,andfabricsoftening.§2.MechanismsofthecleaningprocessThreeelementsincleaningprocessThesubstrate(thesurfacethatistob

3、ecleaned)Hardsurface–glass,metals,andetcSoftsurface–fabric,fiberThesoil(thematerialthatistoberemovedfromthesubstrateinthecleaningprocess)Liquidsoils–oilorfatSolidsoils–blackcarbon,dust,andetc(3)Thebathorcleaningsolution.2.ForcebetweensubstratesandsoilsMechanicalforce–soft&poroussubstrates,par

4、ticlediameterroftheparticles,thenforce,r<100nm,thendifficulttowashoff(2)Electrostaticforce–surfacepotentailwool/water=-48mVcotton/water=-38mVsilk/water=-1mVcationbridge(阳离子桥)-polyvalencyionsSoil---++----------------2.ForcebetweensubstratesandsoilsMechanicalforce–soft&poroussubstrates,par

5、ticlediameterroftheparticles,thenforce,r<100nm,thendifficulttowashoff(2)Electrostaticforce–surfacepotentailwool/water=-48mVcotton/water=-38mVsilk/water=-1mVcationbridge(阳离子桥)-polyvalencyionsElectrostaticforce>MechanicalforceSoil------------------++++(3)Chemicalforce–polarsoilsproteins,fa

6、ts,oxidesetcHydrogenbondandelectrovalentbond(4)VanDerWaalsforce–interactionsbetweenpolar&polarorpolar&non-polarornon-polar&non-polarTwocleaningprocess:removalofthesoilfromthesubstratessuspensionofthesoilinthebathandpreventionofitsredeposition(再沉淀)3.RemovalofthesoilfromthesubstratesItnotcovert

7、heremovalofsoilbymechanicalwork,orchemicalreagents(e.g.bleaches,reducingagents)orenzymesRemovalofliquidsoil–roll-backorroll-upYoungequation:SO=SB-BOCosCos=(SB-SO)/BOSO,Cos,,thenroll-upSB,Cos,,thenspreading(b)Roll-upforceR: