工业结晶学第一讲

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1、工业结晶学第一讲主讲人：孙擎擎outline•Introduction•Drivingforce---supersaturationandchemicalpotentials•Basicconceptsofnucleation•Metastablezone---theoryandexperimentalmethods1.Introduction•Basicprocessinchemicalindustry.•Thefirsttheoreticalworkspublishedattheendof19thcentury.•Data:notall

2、reliable;greatdiscrepancy;oversimplificationofmodelconcepts.•Mullin:1972,semiquantitative•Fewbooksdealwithsecondarynucleationindetail•Symbols:P13~P16.（依据欧洲化工联合会结晶分会）2.Drivingforce•2.1supersaturation•2.2concentrationunits•2.3thermodynamicdrivingforce•2.4activitycoefficients

3、---calculationandexperimentalmethods2.1supersaturation•thenumericalvalueofΔC,Sandσisdependentonthechoiceofunits.2.2concentrationunitsmolefractionconcentrationintechnicalpracticemolarconcentrationnumberofgramsofthecomponentper100gofsolventmolality2.2concentrationunitsmassfr

4、actionAttention!weightpercentsanhydroushydratesdifferent!!!2.3thermodynamicdrivingforce•differenceinthechemicalpotentialwhereSaisthermodynamicsupersaturationratio2.3thermodynamicdrivingforce2.3thermodynamicdrivingforcedrivingforceofcrystallizationforsomeinorganichydratesin

5、25℃2.4activitycoeffici---calculation2.4activitycoefficients---experimentalmethods•蒸气压法•德拜-休克尔极限公式法•图解积分法•测量电动势法•常由实验及理论计算得出3.Basicconceptsofnucleation•asolidphaseis•methods:precipitatedfromcooling;evaporating;solutioniftheadiabaticevaporation;chemicalpotentialofaddingaless

6、efficientthesolidphaseislessthanthatofthesolvent;dissovledcomponentsalting-out;tobeprecipitatedchemicalreaction;fromsolution.electrochemically.3.Basicconceptsofnucleation•twostages:nucleationandcrystalgrowth.•nucleation:primaryandsecondary;takeplaceinmetastablezone.3.Basic

7、conceptsofnucleation•左图是平均晶体大小与成核速度及长大速度的关系•左式是析出晶体质量与晶体大小及晶体数量的关系，可见：若N1>N2，则L

8、lledtothesolutioncurve.•consideredtobetheresultofkineticsofpartofthephasenucleationofthes