南农生物分离工程超临界.pptx

書式設定,書式設定,第,2,第,3,第,4,第,5,#,超临界流体萃取,(,Supercritical Fluid,Extraction),超临界流体的发展,1822年,Cagniard,首次报道物质的临界现象,1869年,Andrew,测定,CO,2,的临界参数,1879年,Hannay,Hogarth,超临界流体对固体有溶解力,1970年,Zosel,采用,sc-CO,2,萃取技术提取咖啡因,1992年,Desimone,sc-CO,2,为溶剂，超临界聚合反应,Michel Perrut,国际超临界流体发展委员会的奠基人,80年代是超临界萃取发展的10年，,90年代已经集中在超临界条件下进行材料合成了，,目前致力于超临界反应的进展。,超临界流体的定义,临界状态是物质的气、液两态能平衡共存的一个边缘状态,在这状态下,液体和它的饱和蒸汽密度相同,因而它们的分界面消失,这状态只能在一定温度和压强下实现,此时的温度和压强分别称为,“,临界温度,”,和,“,临界压强,”,。,SOLID,GAS,LIQUID,SUPERCRITICAL,FLUID,Triple,point,Critical,point,Pressure(bar),Temperature(C),74,31.1,C,-56.3,C,5.1,Phase diagram for pure CO,2,Monterey Bay Aquarium Research Institute,-78,C,1,SOLID,GAS,LIQUID,SUPERCRITICAL,FLUID,Triple,point,Critical,point,Pressure(bar),Temperature(K),303,74,SOLID,GAS,LIQUID,SUPERCRITICAL,FLUID,Triple,point,Critical,point,Pressure(bar),Temperature(K),303,74,SOLID,GAS,LIQUID,SUPERCRITICAL,FLUID,Triple,point,Critical,point,Pressure(bar),Temperature(K),303,74,SOLID,GAS,LIQUID,SUPERCRITICAL,FLUID,Triple,point,Critical,point,Pressure(bar),Temperature(K),303,74,Supercritical Fluid,Both Gas and liquid phases have the same densities in this range.,Carbon Dioxide is normally used since it,s critical point is,at,73.8 bar,and,31.1 degree Celsius,a very easily reached condition,Two Separate phases of,Carbon Dioxide,One Supercritical Phase,Of Carbon Dioxide,SCFs are intermediate between liquids and gases,纯二氧化碳密度随压力与温度的变化,特点:,在临界点附近,密度有很宽的变化范围;,温度,压力微调,可使密度显著变化,g/L,纯二氧化碳在40下的密度,粘度,自扩散系数密度值随压力的变化关系,Variation of solvent power of CO,2,with pressure,Density(gml,-1,),Hildebrand parameter(cal cm,-3,),0.5,310,K=37C,320K=47 C,330K=57 C,超临界流体的性质,物理特征,密度 （,g/cm,3,）,粘度（,g/cm/s）,扩散系数 （,cm,2,/s）,气体,（0.6-2）*10,-3,（1-4）*10,-4,0.1-0.4,液体,0.6-1.6,（0.2-3）*10,-2,（0.2-2)*10,-5,SCF,0.2-0.9,（1-9）*10,-4,（0.2-0.7)*10,-3,SCF,传递特性与气体，液体的特征比较,超临界流体的主要特性,密度类似液体，因而溶剂化能力很强，压力和温度微小变化可导致其密度显著变化,压力和温度的变化均可改变相变,粘度,扩散系数接近于气体，具有很强传递性能和运动速度,SCF,的介电常数，极化率和分子行为与气液两相均有着明显的差别,Common supercritical fluids,Supercritical fluids are substances above their critical temperatures and pressures,whose properties are intermediate between those of gases and liquids,and which can be controlled by both temperature and pressure.,Carbon dioxideT,c,=31.1 C P,c,=73.8 bar,FluoroformT,c,=25.9 C P,c,=48.2 bar,三氟甲烷,WaterT,c,=374.0 C P,c,=220.6 bar,AmmoniaT,c,=132.4 C P,c,=113.2 bar,氨,EthaneT,c,=32.2 C P,c,=48.7 bar,乙烷,为什么选,用,二氧化碳？,温和的临界条件,无毒对设备无腐蚀,阻燃,价廉易得,超临界,CO,2,溶解能力强,适用于化工、医药、食品等工业,超临界流体萃取原理：,将超临界流体与待分离的物质接触，使其有选择性地把极性大小、沸点高低和分子量大小的成分依次萃取出来。对应各压力范围所得到的萃取物不可能是单一的，但可以控制条件得到最佳比例的混合成分，然后借助减压、升温的方法使超临界流体变成普通气体，被萃取物质则完全或基本析出。,Very soluble Sparingly solubleInsoluble,Non-polar andChlorophyll,waxes,Sugars,proteins,moderately polar molecules and carotenoids Tannins,amino,500 MW,叶绿素,蜡,acids and most,类胡萝卜素,pesticides,杀虫剂,Examples,Triterpenoids,三萜类,Alkaloids,生物碱,lipids 95%.No d.e.is observed in conventional solvent.,No diastereoselectivity observed in conventional solvent!,Optimum density is ca.0.7g/ml,R.S.Oakes,A.A.Clifford,K.D.Bartle,M.Thornton Pett,and C.M.Rayner,Chem.Commun,.,1999,247,;,M.Ali,R.S.Oakes,A.A.Clifford and C.M Rayner,unpublished results.,Stereochemistry confirmed by X-ray Crystallography,Other substrates,Replacing the Cbz group with Boc has a significant effect on selectivty,No diastereoselectivity observed in conventional solvent,Major isomer is now syn!,R.S.Oakes,A.A.Clifford,K.D.Bartle,M.Thornton Pett,and C.M.Rayner,Chem.Commun,.,1999,247,;,M.Ali,R.S.Oakes,A.A.Clifford and C.M Rayner,unpublished results.,Solvent Stabilisation in a Supercritical Fluid,In a SCF we can change the solvent density and hence the number of stabilising solvent molecules.,Therefore,as density changes so does stabilisation:,Low density-low stabilisation.,Medium density-high stabilisation.,High density-repulsion comes in to effect hence reduced stabilisation.,EVIDENCE:Variation of solubility with density(e.g.naphthalene),Low density,Small number of interactions,Medium density,Many interactions,High density,Significant,repulsive,forces,超临界水中的氧化反应,超临界水氧化是一种对有机废料处理的新技术。优点是被处理的有机物和氧在超临界水(,P218atm,T374),中完全互溶,可使,有机物,迅速,地分解成二氧化碳、水、氮气以及盐类等无害成份。可处理酚类化合物,卤代烃化合物等.与传统湿式空气氧化法,焚烧法和生化处理法相比,具有明显的优势。,Supercritical fluid,chromatography(SFC),a.,mobile phase is a supercritical fluid.,b.,first proposed in 1958 by J.Lovelock.,first report use was in 1962 by Klesper et al,who used it,to separate thermally-labile porphyrins(,卟啉,).,c.permits the separation and determination of,a group of compounds that are not conveniently handled by either GC or LC,.,non-volatile or thermally labile so that the GC are in-applicable,contain no functional groups for detection by spectroscopic or electrochemical techniques employed in LC.,Theory of SFC,a.One of advantages is that supercritical fluid have lower densities and viscosities than liquids.This results in,larger diffusion coefficients for solutes in SFC,than LC.This results in Better efficiencies,and higher optimum linear Velocities,in SFC than LC.,b.SFC have higher densities than gas,so that mobile phase has a greater chance of interacting with the solute than that in GC(i.e.,carrier gas).This makes the mobile phase important in determining the retention of solutes on the system and give more flexibility in optimizing the separation.For example,retention of solutes in SFC can be changed by using a different column(i.e.different stationary phases)as in GC,or by changing the mobile phase strength as in LC.,cOne major advantage of SFC is its ability to use detector available for either GC or LC,such as FID,UV-Vis,and Fluorescence detectors.This gives it a wide range of both universal and selective detections for use in either analytical or preparative-scale work.,d.Depending on which supercritical fluid is used,it is also possible to use SFC at lower T than GC.This makes it more useful in the separation of thermally unstable compounds.,e.The stationary phases used in SFC can be similar to those in LC as well as GC.Either packed or open-tubular columns may be used.,Because of these advantages,SFC is commonly viewed as a technique which is complementary to both LC and GC.,Instrumentation,a.Instrumentation for SFC can be obtained commercially or adapting system used for either LC and GC.,b.The main difference of a SFC than a LC or GC system is the,need to control both temperature and pressure of mobile phase.This must be done to keep the mobile phase as a supercritical fluid.Control of the pressure(density)of the,supercritical fluid can also used to vary strength of mobile phase during the gradient elution in SFC.,isobaric,Pressure programming,Flow-rate programming,Supercritical fluid chromatography,Applications,By now,SFC has been applied to a wide variety of materials,including natural products,drug,foods,pesticides and herbicides,surfactants polymers,and polymer additives,fossil fuels,and explosives and Propellants.,超临界流体技术展望,虽然超临界流体技术在许多方面已得到应用,但还远没有发挥其应有的作用.这主要是因为目前对超临界流体性质的认识还远远不够。从目前发展趋势看,超临界技术将在以下方面发挥重要作用:,超临界萃取方面,虽然其发展历史较长,但仍保持其强劲的发展势头,在食品、医药等工业领域将发挥越来越重要的作用.,化学反应工程方面,环境友好的超临界流体将取代一些有害的有机溶剂,并且使 反应效率更高,甚至有可能得到通常条件下难以得到的产品.,材料科学方面,超临界技术应用前景十分广阔,其中包括聚合物材料加工、不同 微粒的制备、药物的包封、多孔材料的制备、喷涂、印染等等.,环境科学方面,超临界水为有害物质和有害材料的处理提供了特殊的介质.随着 腐蚀等问题的解决,超临界水氧化处理污水、超临界水中销毁毒性及危险性物质 等可能很快实现商业化.另外,超临界流体技术在土壤中污染物的清除与分析等方面也具有一定的应用前景.,生物技术方面,超临界技术在蛋白质的提取和加工、细胞破碎中的应用等已引起重视.,洗涤工业中,超临界流体清洗纺织品、金属零部件等具有许多优点。,