用微扰硬球链理论计算超临界CO-2-溶质二元系的密度

溶质在超临界流体中的溶解度与流体的密度密切相关。本文采用微扰硬球链理论对纯CO2及CO2-正戊烷、CO2-正庚烷、CO2-正癸烷体系在不同条件下的密度进行计算，计算值与文献给出的实验值符合很好。     

超临界氮气对聚苯乙烯微观形态的影响——喷泉效应与层状结构的形成

当流体的温度和压力处于它的临界温度和临界压力以上时,称该流体处于超临界状态,为超临界流体.超临界流体表现出许多不同于一般气体和液体的特性,如溶质在超临界流体中的溶解度可较同温常压下溶质在同种气体中的溶解度大很多,超临界流体密度与液体的密度相近,其粘度却比液体小近百倍,导热系数比常压气体大得多等.由于超临界流体具有这些不同寻常的特性,因而以超临界萃取为代表的超临界流体已有广泛的工业应用.近年来超临界流体在聚合物加工中的应用逐渐受到重视,如超临界分级、造粒、气体辅助注塑成型、发泡成型等[1～3].     

分散红60在超临界CO2中的溶解度实验研究

有关分散染料与超临界CO2二元体系的相平衡数据(溶解度)实验测定及模型关联,对超临界流体染色工艺基础研究及工业化至关重要。本文建立了高压溶解度测试实验装置,在温度353～393K、压力15～30MPa条件下,对分散红60在超临界CO2中的溶解度进行了测定。并利用zcan经验公式对实验结果进行关联,关联结果和实验结果吻合较好,最大误差为9.3%。结果表明:体系的压力、温度和混合物密度是影响分散染料在超临界CO2中溶解度的重要因素;可利用zcan经验公式对染料等固体物质在超临界CO2中的溶解度进行关联计算。     

超临界CO_2萃取中草药活性成分溶剂特性研究

针对超临界二氧化碳流体的局限性和中草药中活性成分的特殊性,研究了超临界二氧二化碳流体、改性剂和混合溶液的溶解度参数,提出了改性剂的选择原则。结果表明:萃取温度和压力是影响超临界二氧化碳流体和混合溶剂溶解度参数的主要因素,改性剂的种类和浓度影响萃取体系的溶解特性。     

衍生-超临界流体萃取金属离子的技术与进展

综述了近年来衍生-超临界流体萃取环境样品和环境模拟样品中金属离子的研究报道,结合作者的研究工作,着重评述了超临界流体萃取不同环境样品、环境模拟样品中金属离子的原理、萃取过程的动力学模型、衍生剂的选择原则、金属螫合物在超临界流体中的溶解度理论、影响萃取效率的因素、金属离子超临界流体萃取应用研究现状与进展等。利用流体与基体改性技术实现了金属离子和金属螯合物的超临界流体萃取,且在萃取体系中加入适量的表面活性剂能显著提高萃取效率。     

致密气藏储层干化剂在超临界CO2中的溶解性及增溶研究

以离子型碳化物A_XC_Y作为干化主剂注入致密气藏储层中与地层水发生化学反应能够消耗地层水、降低储层含水饱和度,从而提高气体渗流能力。但由于致密气藏储层孔喉较小,固体A_XC_Y颗粒通常难以直接注入其中,因此需要寻找一种有效的干化剂注入方法。通过实验研究发现,超临界二氧化碳(SCCO_2)能够溶解少量无机化合物A_XC_Y,且降压后A_XC_Y析出。故可采用SCCO_2作为输送剂将A_XC_Y溶解并将其有效带入致密储层孔隙中。以此为基础,本文进一步研究了温度和压力对A_XC_Y在SCCO_2中的溶解度的影响;并对多种物质进行测试,优选出了最佳的夹带剂及其用量对A_XC_Y进行增溶。研究结果表明:A_XC_Y可溶解于SCCO_2,在8MPA、40℃下的溶解度为0. 0005mol·mol;且溶解度随压力的升高而增加,但温度对溶解度的影响随压力的变化呈现出非单一的变化规律;此外,以乙醇作为夹带剂具有明显且优于其他物质的增溶效果,其最佳摩尔浓度为10%。     

超临界流体萃取金属离子在环境分析上的应用

固体和液体中的金属离子能在含有有机螯合剂的超临界二氧化碳(SC-CO2)流体中被有效地萃取出来。超临界流体萃取(SFE)金属离子的效率取决于下列因素：螯合剂在SC-CO2中的稳定性和溶解性、金属络合物在SC-CO2中的溶解度、水、pH值、压力、温度及金属离子的化学形式和基质的性质等。     

超临界CO_2流体萃取金线莲中的腺苷

本文研究了超临界CO_2流体萃取金线莲中腺苷的方法。文中用光度法测定腺苷的含量,分别用单因素和正交设计试验对超临界CO_2流体萃取腺苷的条件进行优化。结果显示萃取腺苷的最佳条件为:温度55℃,压力37 MPa,静态萃取时间45 min,夹带剂为85%甲醇,夹带剂用量4 mL。在最佳萃取条件下,金线莲中腺苷的提取量为425.85μg·g~(-1)。     

醌类化合物的超临界流体萃取研究进展

综述了国内近20年来超临界流体萃取技术应用于醌类化合物分离的研究进展,重点介绍了超临界流体萃取技术在中草药中醌类化合物的分析测定方面的应用,分析了影响醌类成分提取效果的主要因素,优化萃取温度和萃取压力能够改善琨类化合物的分离效果,夹带剂的使用则有效地提高了超临界流体的萃取能力。     

水杨酸在二氧化碳－正丁醇混合超临界流体中的溶解度

水杨酸在二氧化碳－正丁醇混合超临界流体中的溶解度柯杰，韩布兴，闫海科，赵扬（中国科学院化学研究所，北京１０００８０）超临界流体（ＳＣＦ）是对比温度和对比压力同时大于１的流体。这种流体具有许多特性，如各种性质随温度和压力的变化十分敏感（特别在临界点附近...     

Entrainer effect in supercritical mixtures

The objective of this paper is to propose a predictive method for the estimation of the change in the solubility of a solid in a supercritical solvent when another solute (entrainer) or a cosolvent is added to the system. To achieve this goal, the solubility equations were coupled with the Kirkwood–Buff (KB) theory of dilute ternary solutions. In this manner, the solubility of a solid in a supercritical fluid (SCF) in the presence of an entrainer or a cosolvent could be expressed in terms of only binary data. The obtained predictive method was applied to six ternary SCF–solute–cosolute and two SCF–solute–cosolvent systems. In the former case, the agreement with experiment was very good, whereas in the latter, the agreement was only satisfactory, because the data were not for the very dilute systems for which the present approach is valid.     

Solubility of solid mixtures in supercritical fluids

Kurnik, R.T. and Reid, R.C., 1982. Solubility of solid mixtures in supercritical fluids. Fluid Phase Equilibria, 8: 93-105Supercritical fluids are receiving widespread attention as possible extraction agents for relatively non-volatile solids and liquids. Previous studies of the solubility of solids in supercritical fluids have been limited to pure solids. These pure-component data are interesting and indicate novel properties of supercritical fluids in this respect. The more general problem, however, lies in determining the solubility of multicomponent solids in supercritical fluids. Experimental data have now been obtained on the solubilities of binary, solid hydrocarbon mixtures in both supercritical carbon dioxide and supercritical ethylene. Most of the behavior exhibited by pure solids in supercritical fluids still exists for multicomponent solid solute systems (e.g., retrograde solidification, solubility extrema), but new phenomena were also found. The most interesting finding is that the solubility of a solid component when in a multicomponent solute system can be as much as 300% higher than the component solubility in a pure solid system at the same operating conditions. The multicomponent-solid-fluid data usually correlate well with thermodynamic theory.     

Use of supercritical fluids in inorganic analysis

The possibilities, advantages, shortcomings, and prospects of using supercritical fluids for separating and extracting metal complexes with organic reagents are considered. The theoretical bases of supercritical fluid chromatography and factors influencing the separation of metal complexes (nature of the organic reagent, solubility of reagents and complexes in a supercritical fluid, type of column, motionless phase, addition of a modifier into the mobile phase, and the test solvent) are discussed. The processes occurring in complexes during chromatography are discussed. The bases of supercritical fluid extraction and factors influencing extraction of metals (nature and solubility in a supercritical fluid of an organic reagent and complexes; concentration and ways of introducing the reagent into the system; addition of the modifier, water, and surfactants; the collector; and the matrix) are considered. The possibilities of methods for determining metals in various objects are shown.     

On the suitability of the virial equation for modeling the solubility of solids in supercritical fluids

Five model systems, the van der Waals fluid, the Soave-Redlich-Kwong fluid, the Peng-Robinson fluid, the hard-sphere fluid, and the square-well fluid, are used to examine the performance of the truncated virial expansion in describing the fugacity of a solute at infinite dilution in a solvent. It is demonstrated that the virial fugacity results deteriorate at significantly lower densities as the solute becomes larger. This has consequences for attempts to describe the solubility of solids in supercritical fluids, where the virial expansion, truncated after the third virial coefficient, has been considered as a modeling option. The results of this work suggest that, for the densities and solute-to-solvent size ratios commonly encountered in supercritical extraction, the truncated virial expansion should not be expected to describe correctly the solute fugacity, and therefore any success it has in fitting solubility data should be viewed with caution.     

基于Hansen溶度参数的煤直接液化残渣超临界萃取

以丙酮、 异丙醇和苯为溶剂在超临界状态下对煤直接液化残渣进行萃取, 应用溶度参数分析了超临界萃取环境中溶剂和萃取原料的变化; 基于Hansen拓展方法建立了关联Hansen溶度参数和萃取收率的理论方程. 结果表明, 临界温度较高. 以色散力溶度参数为主的苯的萃取收率明显高于其它2种溶剂; 液化残渣中可萃出组分的理想溶解度随温度的升高而增大, 该效应也是超临界溶剂萃取重质组分时萃取收率提高的重要原因; 萃取收率与Hansen溶度参数之间的回归模型与实验结果具有较好的一致性, 证明Hansen溶度参数理论和Hansen拓展方法适用于描述煤直接液化残渣的超临界萃取过程.     

Models to predict solubility in ternary solvents based on sub-binary experimental data

The capability of the extended forms, of two well established cosolvency models, i.e. the combined nearly ideal binary solvent/Redlich-Kister equation and the modified Wilson model, used to predict the solute solubility in non-aqueous ternary solvent mixtures is presented. These predictions are based on the measured solubilities of anthracene in binary solvent mixtures. As a result the values of average percent deviations were less than 2% for the anthracene solubility in ternary mixtures. This work was also extended to other cosolvency models, ie. the extended Hildebrand solubility approach and the mixture response surface method, which are also commonly used for correlating solubility data in ternary solvents. The accuracy of the models is compared with each other and also with a published solubility model for ternary mixtures. The results illustrate that all models produced comparable accuracy.     

Supercritical fluid extraction of organic and inorganic mercury from solid materials

Mercuric ions (Hg(2+)) can be extracted from solid samples (cellulose matrix) using methanol modified supercritical CO(2) containing the fluorinated chelating agent lithium bis(trifluoroethyl)dithiocarbamate (LiFDDC). Methylmercuric chloride (CH(3)HgCl) and dimethylmercury [(CH(3))(2)Hg] can be extracted by supercritical CO(2) without chelating agent and modifier. The solubility of Hg(FDDC)(2) in supercritical CO(2) has been determined to be 5 x 10(-3)M at 5O degrees C and 150 atm, which is about 3 orders of magnitude greater than that of the non-fluorinated analogue Hg(DDC)(2). Use of methanol (5%)-modified CO(2) further enhances the solubility of Hg(FDDC)(2) by a factor of 2.4. A small amount of water added to the sample matrix tends to facilitate the extraction of Hg(FDDC)(2) and CH(3)HgCl. Potential applications of this in situ chelation-supercritical fluid extraction method for the preconcentration of mercury species and treatment of mercury contaminated wastes are discussed.     

Solubilities of benzoin,propyl 4-hydroxybenzoate and mandelic acid in supercritical carbon dioxide

A semi-flow type apparatus was used to measure the equilibrium solubilities of benzoin , propyl 4-hydroxybenzoate, and mandelic acid in supercritical carbon dioxide at 308.15, 318.15, and 328.15 K over the pressure range from 9 to 24 MPa. New equilibrium data of solid solubility in supercritical carbon dioxide are presented. The approach to solid–fluid phase equilibrium is examined based on a plug flow fluid–solid mass transfer model. The Soave–Redlich–Kwong and the Peng–Robinson equations of state (EOS), with the van der Waals and the Huron–Vidal type mixing rules were used to correlate the experimental data. The solid solubility data were also correlated with density based semi-empirical equations of Chrastil, and Santiago–Teja. It is shown that these solid solubility data are correlated with reasonably good accuracy using optimally fitted parameters.     

Packed column supercritical fluid chromatography with light-scattering detection. II. Retention behaviour of squalane and glucose with mixed mobile phases

Summary Evaporative light scattering detectors can be used to detect organic substances without chromophoric groups in packed column supercritical fluid chromatography (SFC). A detector of this type has been used to detect squalane and glucose after SFC with various packed columns and binary mobile phases. In this study, the amount of organic modifier in carbon dioxide/modifier mixtures was varied. The results give further insight into the mechanisms that influence retention behaviour in packed column separations with super- and subcritical mobile phases. Squalane is an ideal non-polar test solute which shows long retention times on non-polar columns while its elution can be accelerated by non-polar modifiers in carbon dioxide. Glucose is an extremely polar solute containing hydroxyl groups. Elution of this sugar can be improved with polar modifiers. Column packings with polar end groups lead to high capacity ratios and long retention times for glucose. Most columns used in this study contained silica-based packing materials. For purposes of comparison, a polymeric packing (HEMA RP-18) was also employed.