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Experimental data on the binary solubilities of a large number of low-volatile liquids in supercritical solvents (carbon dioxide and propane) are generalized by the entropy method of the similarity theory over wide temperature and pressure ranges. Two groups of similar systems are revealed which correspond to different entropy ranges of the pure solvent. The mechanism of the dissolution of liquids in supercritical fluids was found to be mainly physical. 相似文献
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《分离科学与技术》2012,47(6):1557-1576
Abstract The use of solvents at conditions above their critical points is increasing because of their increased dissolving power and enhanced transport properties, as in caffeine extraction, etc. This research sought an improved method for correlating the solubility of materials in light solvents from conditions below the critical point of the solvents to those above it, especially to facilitate prediction, interpolation, and extrapolation of solubility data better than existing equations. Solvent density was recognized early as a factor in solvent dissolving power but not used as a correlating parameter. A density approach based on mass-action equilibrium law employing the solvation concept was used to correlate the data on selected binary mixtures with excellent results. For high pressures the relationship yields a plot of log solute solubility (g/L solution) versus log solvent density (g/L solution) which is sectionwise linear. A simplification of the relationship applies well at lower pressures. For both regions, experimental data are represented more easily and better than by conventional equations of state. 相似文献
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超临界流体色谱法测定固体在二氧化碳中的溶解度 总被引:2,自引:0,他引:2
开发了一种测定超临界二氧化碳中大分子溶质的溶解度的方法。这一方法将微型超微界流体萃取直接与超临界色谱相耦合,超临界流体色谱采用FID作为检测器。实验中两者具有同一压力、温度及同样的CO2流速度。 相似文献
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A dynamic experimental set-up was utilized to measure ibuprofen solubility in supercritical CO2 at the pressure range of 8-13 MPa and the temperatures of 308, 313 and 318 K. Mole fraction values varied from 0.015×10^-3 to 3.261×10^-3 and correlated by using seven different semi empirical equations of state (Bartle, Modi-fied Bartle, Mendez-Teja, Modified Mendez-Teja, Kumar-Johnson, Sung-shim and Gordillo) as well as seven cubic equations of state (van der Waals, Redlich-Kwong, Soave-Redlich-Kwong, Peng-Robinson, Stryjek-Vera, Patel-Teja-Valderana and Pazuki). Single and twin-parametric van der Walls mixing rules (vdW1, vdW2) were ap-plied in order to estimate the supercritical solution properties. The physicochemical properties were also obtained using Joback, Lydersen and Ambrose methods. Absolute average relatives deviation (AARD) were calculated and compared for all the correlating systems. Results showed that among the cubic equations of state (EOSs) the Pazuki equation (AARD=19.85% using vdW1 and AARD=8.79% using vdW2) and SRK equation (AARD=19.20%using vdW1 and AARD=10.03%using vdW2) predicted the ibuprofen solubility in supercritical CO2 with the least error in comparison to the others. Among the semi-empirical EOSs the most desirable deviation (AARD〈10%) was obtained by using Modified Bartle and Modified Mendez-Teja equations in all the studied temperatures. 相似文献
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《分离科学与技术》2012,47(7-9):1901-1915
Abstract Several supercritical fluid extraction (SCFE) processes have been proposed for removing toxic and intractable organic compounds from a range of contaminated solids. These include soil remediation and the regeneration of adsorbents used to treat wastewater streams such as granular activated carbon (GAC). As a separation technique for environmental control, SCFE has several distinct advantages over conventional liquid extraction methods and incineration. Most notably, the contaminant is removed from the solvent in a concentrated form via a change in pressure or temperature and can be completely separated upon expansion to atmospheric pressure. The viability of SCFE hinges on process conditions such as solvent-feed ratio and solvent recycle ratio. The necessity of recycling solvent complicates the contaminant separation step since a complete reduction to atmospheric pressure would create large recompression costs. Because of this, the pressure and temperature dependence of contaminant solubility must be understood so that operating conditions for the separation step can be defined. Fortunately, this is the most developed aspect of SCF technology. However. the mass transfer limitations to removing contaminants from solids change with solvent flow rate. This paper discusses the use of SCFE for environmental control and presents results for the removal of DDT and 2-chlorophenol from GAC. 2-chlorophenol is almost completely removed with pure CO2 at 40°C and 101 bar while only 55% of the DDT is removed at 40°C and 200 bar. These differences in regeneration efficiency cannot be understood solely in terms of solubility but point to a need for detailed studies of adsorption equilibrium and mass transfer resistances in supercritical fluid systems. 相似文献
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测定了2-羟基苯甲酸在308.15K和328.15K,10.0-25.0MPa条件下,在含和不含夹带剂的超临界CO2中的溶解度数据;分析了夹带剂对超临界流体中固体溶质溶解度的作用机理,得到选择夹带剂的一般原则。 相似文献
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A system for oxidation of organic impurities in supercritical water is proposed. Models are formulated and calculations are performed to determine the characteristics of the main apparatuses of the system, namely, heat exchangers, a chemical reactor, and a separator. The models take into account specific features of processes under supercritical conditions, specifically, the changes in the thermodynamic properties (enthalpy, specific heat, critical parameters) of the reaction mixtures with changes in pressure and temperature, and also the variations of the compositions of the mixtures along the lengths of the apparatuses. The thermodynamic properties are calculated by methods of nonequilibrium thermodynamics. A numerical analysis is performed of one of the variants of a system for acetic acid oxidation by oxygen in supercritical water, which can be a prototype of a pilot plant. The fuel is chosen to be an aqueous methanol solution, and the oxidant is taken to be hydrogen peroxide. Replacement of the reactant, the fuel, or the oxidant does not fundamentally change the methods for calculating the characteristics of the apparatuses and the entire system. 相似文献
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文章阐述了超临界流体分离技术的原理、流程与特点.综述了该技术在分离工程领域的应用方向、存在的问题及未来的发展前景.指出了该技术兼具精馏和萃取两种分离作用效果,在天然资源成份的分离提取、脱除有害成份或杂质、清洗、色谱分析等诸多领域部有着其独特的开发应用优势. 相似文献
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