Supercritical-fluid-extraction-超临界流体提取课件.ppt

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1、Supercriticalfluidextraction(SFE)/Supercriticalfluidchromatography(SFC)SupercriticalFluid(SCF)AttemperaturesaboveTcandpressuresbeyondPc,substanceexistsassupercriticalfluid,andnotasgasorliquid.TheSCFexpandsandcontractslikegasandhassolventpropertieslikeliq

2、uid.PhasediagramforsupercriticalfluidComparisonofthepropertiesofgas,SupercriticalfluidandliquidMobilephaseDensity(g／ml)Viscosity(m2／s)Diffusioncoefficient(cm2／s)Gas0.6～2.0×10-3(0.01)0.5～3.5×10-4(0.01)0.01～1.0(10,000)Supercriticalfluid0.2～0.9(~0.5)2.0～9.9

3、×10-4(0.01)0.5～3.3×10-4(10-100)Liquid0.8～1.0(1)0.3～2.4×10-2(1)0.5～2.0×10-5(1)SCFsareusedasextractionsolvents(e.g.extractingcaffeinefromcoffeebeans,fatsfrompotatochips),carriermediumforchromatography,andsolventsfordisposaloforganichazardouswastesAdvantage

4、sofSupercriticalFluidsloweroperatingtemperaturesimprovedyieldimprovedproductpropertiesfavorablecombinationofprocessstepseasierregenerationoftheSCsolventlowerproductioncostsolventpowercomparabletoliquidsolventsveryhighvolatilitycomparedtothedissolvedsubst

5、ancescompleteseparationofsolventfromextractandraffinateDisadvantagesofSupercriticalFluidselevatedpressuresrequiredrelativehighcostsofinvestmentunusualoperatingconditionscomplicatedphasebehavioraDatatakenfromRefs.62and63.BThedensityat400atm(p,,,,)endT,=1.

6、03wascalculatedfromcompressibilitydata.”Cmeasurementsweremadeundersaturatedconditionsifnopressureisspecifiedorwereperformedat25°Cifnotemperatureisspecified.PhysicalParametersofSelectedSupercriticalFluidsBenefitsofsupercriticalcarbondioxideModeratecritica

7、lpressure(73.8bar)Lowcriticaltemperature(31.1℃)LowtoxicityandreactivityHighpurityatlowcostUsefulforextractionsattemperature<150℃BenefitsofsupercriticalcarbondioxideCtd.IdealforextractionofthermallylabilecompoundsIdealextractantfornon-polarspecies,e.g.alk

8、anesReasonablygoodformoderatelypolarspecies,e.g.PAHsCandirectlyventtoatmosphereLittleopportunityforchemicalchangeinabsenceoflightandoxygenGasatroomtemperature,allowsforcouplingtogaschromatographyandSFCPhasediagramsforCO2an