chapter 5 liquid-liquid extraction：5章液液萃取

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1、Chapter5Liquid-LiquidExtractionSubject:1304332UnitOperationinHeattransferInstructor:ChakkritUmpuchDepartmentofChemicalEngineeringFacultyofEngineeringUbonRatchathaniUniversityHereiswhatyouwilllearninthischapter.5.1IntroductiontoExtractionProcesses5.2EquilibriumRe

2、lationsinExtraction5.3Single-StageEquilibriumExtraction5.4EquipmentforLiquid-LiquidExtraction5.5ContinuousMultistageCountercurrentExtraction25.1IntroductiontoExtractionProcesses“Whenseparationbydistillationisineffectiveorverydifficulte.g.close-boilingmixture,liq

3、uidextractionisoneofthemainalternativetoconsider.”WhatisLiquid-liquidextraction(orsolventextraction)?Liquid-Liquidextractionisamasstransferoperationinwhichaliquidsolution(feed)iscontactedwithanimmiscibleornearlyimmiscibleliquid(solvent)thatexhibitspreferentialaf

4、finityorselectivitytowardsoneormoreofthecomponentsinthefeed.Twostreamsresultfromthiscontact:a)Extractisthesolventrichsolutioncontainingthedesiredextractedsolute.b)Raffinateistheresidualfeedsolutioncontaininglittlesolute.3Liquid-liquidextractionprincipleWhenLiqui

5、d-liquidextractioniscarriedoutinatesttubeorflaskthetwoimmisciblephasesareshakentogethertoallowmoleculestopartition(dissolve)intothepreferredsolventphase.5.1IntroductiontoExtractionProcesses4Anexampleofextraction:5.1IntroductiontoExtractionprocessesAceticacidinH2

6、O+EthylacetateExtractOrganiclayercontainsmostofaceticacidinethylacetatewithasmallamountofwater.RaffinateAqueouslayercontainsaweakaceticacidsolutionwithasmallamountofethylacetate.Theamountofwaterintheextractandethylacetateintheraffinatedependsupontheirsolubilites

7、inoneanother.5Equilateraltriangulardiagram(AandBarepartiallymiscible.)TriangularcoordinatesandequilibriumdataEachofthethreecornersrepresentsapurecomponentA,B,orC.PointMrepresentsamixtureofA,B,andC.TheperpendiculardistancefromthepointMtothebaseABrepresentsthemass

8、fractionxC.ThedistancetothebaseCBrepresentsxA,andthedistancetobaseACrepresentsxB.xA+xB+xC=0.4+0.2+0.4=1xB=1.0-xA-xCyB=1.0-yA-yC5.2Single-stageliquid-liquidextractionp