Measurement of activity coefficients at infinite dilution for acetonitrile,water, limonene,limonene epoxide and their binary pairs

Activity coefficients at infinite dilution were determined for binary pairs of acetonitrile, water, limonene and limonene epoxide at room temperature using the dilutor technique (inert gas stripping) in a home-made dilutor apparatus. The activity coefficients were predicted with the Aspen Plus software using the Dortmund-modified UNIFAC contribution method. Values predicted by software simulations are in good agreement with experimental data. However, experimental activity coefficients at infinite dilution obtained for limonene + acetonitrile, water + limonene and limonene epoxide + water systems are in disagreement with reported values estimated from LLE or solubility data.     

蒙特卡罗法估算真实溶液的无限稀释活度系数

在无限稀释活度系数实验测定、模型预测等方面的研究工作不断深入的同时，基干系统的微观分子结构信息通过计算机分子模拟方法来求取无限稀释活度系数的研究也更多地开展起来［‘，’］．但是鉴于摘类热力学性质，如自由能、化学位等的特殊性，开展的模拟工作总的说来是初步的·许多方法复杂，实现的难度较大，而研究的系统技多地针对于模型流体混合物（modelfluidrn－ixtures）．本文是蒙特卡罗法估算真实溶液的无限稀释活度系数的一个尝试，研究对象选取298．15K温度条件下甲醇的水溶液·1原理对于一个NTV系综，化学位定义为可以将UN－…     

Prediction of infinite dilution activity coefficients of sulfur dioxide in organic solvents

Infinite dilution activity coefficients of sulfur dioxide in various organic solvents were correlated with two basicity scales: the solvent Gutmann donor number and Arnett heat of hydrogen bonding. Linear correlations were observed for both basicity scales, and the accuracy of activity coefficient prediction is estimated to be ±20 to 25%. Infinite dilution activity coefficients of sulfur dioxide in over 80 organic solvents were estimated from the correlations.     

丙酮—环烷烃体系的无限稀释活度系数的气提法测定研究

如果溶剂是高挥发性物质,当用气提法测定无限稀释活度系数时需要加预饱和釜以消除气提时因溶剂量损失过大而带来的问题.本文就丙酮-甲基环戊烷、丙酮-环己烧和丙酮-甲基环己烷3个体系在298.2～318.2K温度范围内的γ~∞作了测定,用所得数据作全浓度范围的汽液平衡推算,与文献中实验值对比,发现Wilson方程结果最佳.     

Correlation of infinite dilution activity coefficients of solvents in polymer solutions using connectivity indices

In this work, correlations for the estimation of the infinite dilution activity coefficients of non-polar solvents in polystyrene (PS), poly(vinyl acetate) (PVAc), poly(n-butyl methacrylate) (PBMA), poly(dimethyl siloxane), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO), poly(vinyl chloride) (PVC), polyisobutylene and polyethylene (PE), and that of polar solvents in PS, PVAc, PBMA, PMMA, PEO, PVC and PE are proposed. A total of 205 polymer/non-polar solvent systems with 1708 data points, and 118 polymer/polar solvent systems with 695 data points were used to develop the correlations. The overall average errors were 9.6% and 11.3%, respectively, significantly lower than other predictive models. Since the new correlations require only the connectivity indices of the solvents in the calculations, and the connectivity indices can be calculated easily once the molecular structure of the substance in question is known, they are easy to apply, and are useful for process design and development.     

Prediction of infinite dilution solvent activity coefficient in rubbery polymer solutions using Engaged Species Induced Clustering (ENSIC) model

It is extremely important to predict infinite dilution solvent activity coefficients in rubbery polymers in design and operation of polymer‐related processes. Many models have been developed to predict the activity coefficients. However, the accuracies of these models are not satisfactory. This article advances a method for predicting the infinite solvent dilution activity coefficients in the rubbery polymers, using the Engaged Species Induced Clustering (ENSIC) model. It elucidates the physiochemical significance and mathematical meaning of the parameters in the ENSIC model. In this article, the ENSIC approach has been proven to agree extremely well with the experimental data in both correlating the finite dilution solvent activity coefficient and predicting the infinite dilution solvent activity coefficient for rubbery polymer/solvent systems. In other words, both the ENSIC equation and its derivative at extremely low solvent concentration are in good agreement with the experimental data. In addition, the article indicates that the ENSIC model is much more accurate than another kind of empirical models‐ the F–H and related models in predicting the infinite dilution solvent activity coefficients in polymer solutions. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1668–1675, 2006     

Activity coefficients at infinite dilution for surfactants

A new alternative is presented for activity coefficients at infinite dilution determination via surface tension data of low vapour pressure substances. It was found that experimental data for surfactants follows Volmer's surface equation of state behaviour over the diluted region until the critical micelle concentration. The key operations are: the choice of the same standard conditions for the bulk and the surface phases, the combination of Gibbs and Volmer equations and the use of the symmetric activity coefficients convention. An exact relation between the activity coefficient at infinite dilution and the reciprocal of the critical micelle mole fraction was found which allowed us the verification of the model.     

Measurement and prediction of infinite dilution activity coefficients for alkane in alkane within wide temperature

The infinite dilution activity coefficients of alkane (hexane, octane, decane and dodecane) in alkane (hexadecane and octadecane) were measured in the region of 313–470 K using a gas stripping method. The experimental results were predicted by the modified ASOG previously proposed.     

Infinite dilution activity coefficents of hydrocarbons in tetra-n-alkyltin solvents between 40 and 60°C measured by gas-liquid chromatography

Infinite dilution activity coefficients for twenty-three hydrocarbons in tetra-n-amyltin (TAT) and in tetra-n-lauryltin (TLT) at several temperatures between 40 and 60°C were measured by gas liquid chromatography. The results, together with those obtained in an earlier paper in tetra-n-octyltin (TOT), are compared and discussed in terms of the equation of state theory of Flory and of the lattice fluid theory of Sanchez and Lacombe.     

Prediction of phase equilibrium in mixtures containing ionic liquids using UNIFAC

The UNIFAC model is extended to mixtures of ionic liquids consisting of the imidazolium cation and the hexafluorophosphate anion with alkanes, cycloalkanes, alcohols and water. Two new main groups, the imidazolium and the hexafluorophosphate groups, are introduced in UNIFAC. The required group interaction parameters between these groups and the existing UNIFAC main groups, CH₂, OH and H₂O, are determined by fitting binary liquid–liquid equilibrium and infinite dilution activity coefficient experimental data. The predictive capability of the extended UNIFAC model is examined against experimental data for vapour–liquid equilibrium, liquid–liquid equilibrium and activity coefficients at infinite dilution of binary and ternary systems containing 1-alkyl-3-alkyl′-imidazolium hexafluorophosphate ionic liquids, alkanes, cycloalkanes, alcohols and water. The results indicate that UNIFAC is a reliable model for phase equilibrium predictions in mixtures containing this type of ionic liquids.     

Thermodynamics and activity coefficients at infinite dilution measurements for organic solutes and water in the ionic liquid 1-butyl-1-methylpyrrolidinium tetracyanoborate

The activity coefficients at infinite dilution, , for 45 solutes, including alkanes, cycloalkanes, alkenes, alkynes, aromatic hydrocarbons, alcohols, thiophene, tetrahydrofuran, ethers, acetone, and water, in the ionic liquid 1-butyl-1-methylpyrrolidinium tetracyanoborate, [BMPYR][TCB], were determined by gas–liquid chromatography at temperatures from 318.15 K to 368.15 K. The values of the partial molar excess Gibbs free energy , enthalpy , and entropy at infinite dilution were calculated from the experimental values obtained over the temperature range. The gas–liquid partition coefficients, K_L were calculated for all solutes and the Abraham solvation parameter model was discussed. The values of the selectivity for different separation problems were calculated from and compared to literature values for N-methyl-2-pyrrolidinone (NMP), sulfolane, 1-ethyl-3-methylimidazolium tetracyanoborate, [EMIM][TCB], 1-decyl-3-methylimidazolium tetracyanoborate, [DMIM][TCB], and similar ionic liquids. The densities of [BMPYR][TCB] in temperatures range from 318.15 K to 368.15 K, the temperature of fusion and the enthalpy of fusion were measured.     

Vapor–liquid equilibrium calculations for refrigerant mixtures with the Mattedi–Tavares–Castier EOS

The present study uses the Mattedi–Tavares–Castier EOS to investigate VLE predictions for refrigerant binary mixtures. The refrigerant molecules are treated either by the associated-group or the uniform-molecular model. In the associated-group model, the refrigerant molecule is split into three groups: an electron-donor (α), an electron-acceptor (β), and a dispersion group (D). In the uniform-molecular model, the refrigerant molecule is represented as a single group. Results obtained with the MTC EOS are in agreement with experimental data reported in the literature. The EOS that treats refrigerant molecules with groups that can associate gives worse results than the uniform-molecular model.     

Isothermal vapour–liquid equilibrium for cyclic ethers with 1-chloropentane

Isothermal vapour–liquid equilibrium measurements for mixtures containing cyclic ethers: tetrahydrofuran, tetrahydropyran, 1,3-dioxolane or 1,4-dioxane and 1-chloropentane at the temperatures of 298.15, 313.15 and 328.15 K are reported. The thermodynamic consistency of the VLE measurements was satisfactorily checked with the van Ness method. Activity coefficients were correlated with Wilson, NRTL, and UNIQUAC equations. The calculated excess Gibbs functions for tetrahydrofuran and tetrahydropyran are negative over the whole composition range while for 1,3-dioxolane and 1,4-dioxane the excess Gibbs functions are positive.