資源描述：
《Supercritical-fluid-extraction-超臨界流體提取課件.ppt》由會員上傳分享，免費(fèi)在線閱讀，更多相關(guān)內(nèi)容在教育資源-天天文庫。
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
