溶解度参数法计算超临界流体的溶解度

溶质在超临界流体中的溶解度计算方法有热力学模型和经验公式2种,其中经验公式法形式简单,精度接近甚至高于热力学模型,应用广泛。以往的经验公式多用超临界流体密度来关联溶解度,文中选择以溶解度参数为变量,用3个与温度无关的可调参数,建立了超临界流体溶解度计算的经验公式。计算的11种固体在超临界CO2、乙烷和乙烯中溶解度与实验数据的平均相对误差在10%左右。与密度相比,溶剂与溶质的溶解度参数差更能直观地反映出超临界流体对物质的溶解能力,且具有明确的理论基础,应该引起足够的重视和推广。     

乙醇-水溶剂中5'-尿苷酸二钠溶解度测定与关联

采用内置双光路激光检测器,在293.2-318.2 K温度范围内,测定了5'-尿苷酸二钠在纯水及不同乙醇-水混合溶剂中的溶解度.分别用R-K方程、λh方程和Wilson方程3种溶解度模型,采用最小二乘法关联实验数据,并对比不同溶解度模型.结果表明,在乙醇质量分数为0-0.65区间内,5'-尿苷酸二钠溶解度随着温度的升高而增大,随乙醇质量分数的增大而显著减小,λh方程对5'-尿苷酸二钠溶解度关联效果最好.将λ,h表达为乙醇质量分数的函数,并用于内插计算,精度满足工程要求.     

Solubility of supercritical gases in polymers—a review

Processing of polymers is greatly affected by the presence of dissolved gases. Analysis of the effect of dissolved gases requires two types of information: equilibrium thermodynamic data and predictive correlations as well as diffusion rate data and analyses. We review here the state-of-the-art knowledge of the equilibrium thermodynamics of gases dissolved in polymers. The published data are presented and analyzed. Also, we review the latcst theories and predictive correlations for gas solubility in polymers.     

Solubility of cyproheptadine in supercritical carbon dioxide; experimental and modeling approaches

Solubility of solute in supercritical fluids at different pressures and temperatures is one of the most important parameters necessary for design of any supercritical fluid-based processes. Among different supercritical fluids, carbon dioxide is one of the most widely used solvents due to its useful and green characteristics. In this work, with the assist of supercritical carbon dioxide as the solvent, solubility of cyproheptadine in different temperatures (308–338 K) and pressures (160–400 bar) are measured using static method. The obtained results demonstrated that solubility of cyproheptadine ranged between 3.35 × 10⁻⁵ and 3.09 × 10⁻³ based on mole fraction. A closer examination of measured solubility data show that not only solubility of cyproheptadine increases by increasing pressure but also experiences a cross over pressure about 200 bar. At last, the measured solubility data are correlated using four widely used density based correlations namely Mendez Santiago–Teja (MST), Kumar and Johnston (KJ), Bartle et al., and Chrastil models. The obtained results demonstrated that the best correlative capability was observed for KJ model leads to the average absolute relative deviation percent (AARD %) of 6.3%.     

对乙酰氨基苯甲酸在甲醇+乙醇混合溶剂中溶解度测定及关联计算

溶解度的实验和计算是固-液相平衡热力学研究的基础, 为工业结晶分离过程优化提供重要参数。本文以对乙酰氨基苯甲酸为目标溶质, 在标准压力下, 通过激光动态法在277.95~323.35K温度范围内, 测量其在甲 醇+乙醇混合溶剂中(乙醇质量分数0、20%、40%、60%、80%、100%)的溶解度, 分析了溶解过程中的热力学现象。实验数据用Modified Apelblat、修正的Jouyban-Acree两种热力学模型进行了关联计算。结果表明, 两种模型对对乙酰氨基苯甲酸的关联效果都很好, 其中Modified Apelblat、修正的Jouyban-Acree方程的计算值与实验值的平均相对偏差分别为0.702%和1.105%。通过热力学理论分析, 计算得到对乙酰氨基苯甲酸在混合溶液中溶解焓Δ_dH_m和溶解熵Δ_dS_m, 结果发现该溶解过程为放热过程, 焓变对溶解过程影响较大。     

Solubility of supercritical gases in organic liquids

Chrastil (1982) [6] demonstrated that the solubility of a substance in a supercritical fluid (SCF) can be correlated with the density of the pure supercritical gas. Therefore, Chrastil's equation permits calculation of the supercritical phase composition of binary SCF + substance mixture based on the knowledge of the supercritical gas density and avoiding the use of equation of state based models.In this work, it is demonstrated that the supercritical fluid density also defines the liquid phase composition of binary systems; a density-dependent relationship is presented to calculate the solubility of supercritical gases in organic liquids. The isothermal solubility of several gases commonly employed in supercritical processing, such as carbon dioxide, methane, and ethane, in different organic liquids, including alkanes, alkenes, alcohols, acids, ketones, esters, terpenes and aromatic compounds, was successfully correlated as a function solely of the pure supercritical fluid density. As an application, pressure vs. composition phase diagrams of binary SCF + substance mixtures were obtained circumventing the use of equation of state models.     

水在超临界二氧化碳中的溶解度

生物柴油副品油酸的高值化利用是降低生物柴油成本的有效途径之一,为了充分利用生物柴油副品油酸中的壬二酸,用基于超临界流体技术(SCCO2)的固相缩聚方法可制得超高相对分子质量的尼龙69等高分子材料。SCCO2不仅可以作为增强SSP过程的介质使用,还可以有效地将缩聚物(如水等小分子缩聚物)脱除,促进反应的进行,因此测定水在超临界二氧化碳中的溶解度对研究SCCO2增强的SSP过程具有重要意义。文中采用静态法测定了水在超临界二氧化碳中的溶解度,温度为313.15,333.15,353.15,373.15 K,压力为8.0—18.0 MPa,溶解度(摩尔分数)为0.254%—1.414%;探究了温度、压力对溶解度的影响,结果表明:溶解度随温度、压力的升高而升高;利用PR状态方程和Chrastil修正模型对溶解度进行了计算,结果表明溶解度的计算值和实验值吻合良好,平均相对误差分别为4.63%和5.89%。     

Solubility of gabapentin in supercritical carbon dioxide

The purpose of this study was to measure the solubility of gabapentin in supercritical carbon dioxide at different pressures and temperatures of 16–40 MPa and 308–338 K, respectively. The measured solubility data revealed that solubility of gabapentin was 8.97 × 10⁻⁵–7.36 × 10⁻³ based on the mole fraction in supercritical carbon dioxide at the aforementioned operational conditions. At last, the obtained results were correlated using four density based semi-empirical correlations namely Bartle et al., Mendez-Santiago and Teja (MST), Chrastil and Kumar and Johnston (K–J). The results revealed that according to the obtained average absolute relative deviations (AARD) for the used density based correlations of MST (AARD % = 9.88%), Chrastil (AARD % = 9.47%), K–J (AARD % = 11.5%) and Bartle et al. (AARD % = 9.29%), none of the correlations can be considered as the most accurate one. In other words, all the examined semi-empirical correlations are in the same level of accuracy.     

Solubility of astaxanthin in supercritical carbon dioxide

The solubility of astaxanthin in carbon dioxide was measured under supercritical conditions of a pressure range from 80 to 300 bar, and temperature range from 303 to 333 K, by using a dynamic flow-type. The solubility of astaxanthin increasing from 0.42×10⁻⁵ to 4.89×10⁻⁵ with higher temperature and pressure maintains certain density of supercritical carbon dioxide. The solubility data obtained were applied to the Chrastil model, based on the density of carbon dioxide. The data fitted well with the Chrastil model at most experimental conditions.     

One-fluid mixing rules for cubic equations of state: I. Solubility of pure solids in supercritical fluids

Three cubic equations of state are carefully examined to evaluate their capability for correlating the supercritical solubility data of solid solutes in compressed gases. The overall average absolute deviatons between experimental and predicted values for 35 binary systems are 17.33% (Redlich-Kwong), 22.92% (Soave), and 22.93% (Peng-Robinson) using one binary parameter and 12.55% (Redlich-Kwong), 15.57% (Soave), and 13.71% (Peng-Robinson) using two binary parameters.     

One-fluid mixing rules for cubic equations of state: II. Solubility of solid mixtures in supercritical fluids

Three cubic equations of state are carefully examined to evaluate their capability for correlating the solubility of solid mixtures in supercritical fluids. After obtaining the pure solute-solvent interaction parameters, the solute-solute interaction parameters were directly calculated from the experimental ternary solubility data. The Redlich-Kwong, Soave, and Peng-Robinson equations of state correlate well the ternary data. However, the Redlich-Kwong equation of state gives the best result among them.     

Homogeneously-catalyzed syntheses in supercritical fluids

Supercritical fluids (SCFs) differ from liquid solvents in a number of important properties, any of which could potentially alter the performance of a chemical reaction performed in a supercritical medium. Although rate, yield and selectivity improvements as well as environmental, health and engineering benefits are all possible, little research has been reported on homogeneously-catalyzed syntheses in SCFs. Several notable successes plus new techniques for solubilizing hydrophilic reagents in SCFs are encouraging further research in this growing field. This revised version was published online in June 2006 with corrections to the Cover Date.     

超临界流体中的化学反应

超临界流体中的化学反应可分为两大类 ,即超临界流体作为反应介质的反应和超临界流体作为反应原料的反应 ,分别介绍了其研究进展 ,着重介绍了第一类反应中的酶催化反应、超临界水氧化、高分子合成     

Solubilities of solids in supercritical fluids

The solubilities of several low-volatility compounds in supercritical fluids were measured. The fluids used were pure carbon dioxide or carbon dioxide modified with small amounts of organic liquids. Some enthalpies of solution of solids in carbon dioxide at a density of 0.80 g/mL are presented. The enthalpy of solution of fluoranthene in carbon dioxide was found to be less endothermic at higher CO₂ density. The order of solubilities in the modified fluids was the same as that in the pure liquid modifiers. The same apparatus was used to measure vapor pressures of some substances as well as solubilities.     

Solubility of fatty acids in supercritical carbon dioxide

The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC-CO₂) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at 313, 323 and 333°K (40, 50 and 60°C) as a function of SC-CO₂ density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids from triglycerides might be possible by using SC-CO₂ at densities less than 700 kg/m³. From the effect of temperature on fatty-acid and vegetable-oil solubility, it seems that the extraction yield could be increased without sacrificing the selectivity of SC-CO₂ for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature of SC-CO₂ on solute solubility.     

Solubility of chlorpheniramine maleate in supercritical carbon dioxide

Solubility of chlorpheniramine maleate in supercritical carbon dioxide at different temperatures (308–338 K) and pressures (160–400 bar) is measured using static method coupled with gravimetric method. The measured solubility data demonstrated that the solubility of chlorpheniramine maleate was changed between 1.54 × 10⁻⁵ and 4.26 × 10⁻⁴ based on the mole fraction as the temperature and pressure are changed. The general trend of measured solubility data shows a direct effect of pressure and temperature on the solubility of chlorpheniramine maleate. Finally, the obtained solubilities correlated using four semi-empirical density-based correlations including Mendez Santiago–Teja (MST), Kumar and Johnston (KJ), Bartle et al., and Chrastil models. Although the results of modeling showed that the KJ model leads to the average absolute relative deviation percent (AARD %) of 8.1% which is the lowest AARD %, deviation of other utilized correlations are rather the same.     

Extraction and processing with supercritical fluids

OVERVIEW: Extraction and processing with supercritical fluids (SCF) is increasingly gaining importance in the food, pharmaceutical and chemical industries. Supercritical fluid extraction (SCFE) using carbon dioxide (CO₂) as a solvent has emerged as a highly popular technology today over the conventional techniques for extraction of natural products for rapid, contamination‐free, tailor‐made extracts having superior quality and shelf‐life and high potency of active ingredients. IMPACT: The importance of SCFE is on the rise due to consumers' preferences for ‘natural’ as opposed to synthetic substances and, impending regulations for environmental protection, safety, nutritive and toxicity levels. APPLICATIONS: Newer applications of SCFs include separation and purification of chemicals, cleaning, coating, particle formation, textile dyeing, aerogel drying, reactions with separation and food preservation. Some fundamental aspects of SCFs, various processing technologies with SCFs, and a few newer potential applications are presented in this article. Copyright © 2008 Society of Chemical Industry     

铬盐液相氧化工艺分离过程中多元体系溶解度的测定及关联

采用平衡分析法,测定了常压下铬铁矿液相氧化生产铬盐工艺分离过程涉及的NaOH-H₂O-Na₂CrO₄、NaOH-H₂O-NaAlO₂、NaOH-H₂O-Na₂SiO₃三元体系,NaOH-H₂O-Na₂CrO₄-Na₂SiO₃、NaOH-H₂O-Na₂CrO₄-NaAlO₂、NaOH-H₂O-Na₂SiO₃-NaAlO₂ 四元体系及NaOH-H₂O-Na₂CrO₄-Na₂SiO₃-NaAlO₂五元体系中Na₂CrO₄、NaAlO₂、Na₂SiO₃的溶解度,并使用Apelblat方程对实验数据进行了回归。实验的温度范围为353.15～403.15 K,除测量Na₂CrO₄在NaOH-H₂O-Na₂CrO₄三元体系中的溶解度时NaOH的浓度从100 g·L^-1改变到 800 g·L^-1,其他体系中都固定NaOH浓度为500 g·L^-1。研究结果表明铝酸钠、硅酸钠无论单独存在还是同时存在均会降低铬酸钠的溶解度,其中铝酸钠对铬酸钠的溶解度影响最大,而硅铝共存反而对铬酸钠溶解度影响最小。     

Solubility of simple and mixed triacylglycerols in supercritical CO2

A simple mixture of triacylglycerols (TAGs) was synthesized enzymatically from palmitic acid and oleic acid. The mixture contained tripalmitoylglycerol (PPP), trioleoylglycerol (OOO), and various isomers of palmitoyl-dioleoylglycerol (POO) and oleoyl-dipalmitoylglycerol (PPO). The behavior of this TAG mixture in equilibrium with supercritical carbon dioxide (SF-CO₂) was studied at 40 and 60°C between 172 and 310 bar. Generally, the partition coefficients varied inversely with species molecular weight. The solubilities of PPP and OOO in SF-CO₂ were determined at the same conditions. PPP was markedly more soluble in SF-CO₂ when present in the TAG mixture than as a pure compound.     

超临界流体在制膜过程中的应用

介绍了超临界流体诱导相分离过程制备有机膜的工艺流程、原理及特点,并与传统的沉浸凝胶相转化制膜方法进行了比较。同时介绍了超临界流体过程在有机膜的制备和改性方面的研究现状及其研究前景,并对其进一步的研究提出了一些建议。