Semenov Semen N, Schimpf Martin E
Institute of Biochemical Physics RAS, Kosygin Street 4, Moscow 119334, Russia.
Department of Chemistry, Boise State University, Boise, ID, USA.
Phys Chem Chem Phys. 2022 Nov 18;24(44):27432-27440. doi: 10.1039/d2cp03914a.
We extend our nonequilibrium thermodynamic model of thermodiffusion in binary systems to multi-component mixtures. The fundamental parameter is the difference in molecular entropy of the components, which can be obtained in one of three ways; (i) derived as temperature derivatives of the respective equilibrium chemical potentials at constant pressure using equilibrium statistical mechanics; (ii) obtained in the literature from computer simulations; or (iii) obtained as empirical values in the literature. The model is used to relate thermodiffusion in multicomponent mixtures of related isomers or isotopes to isomer/isotope effects in binary mixtures that are commonly enumerated in one of two ways: (i) as a difference in the Soret coefficients measured on two binary mixtures, each containing one of two related isomers/isotope in a common solvent; or (ii) as this difference from two binary mixtures, each consisting of a common solute dissolved in one of the two related isomers/isotopes as the solvent. The model is used to estimate the concentration profiles established in neat multicomponent mixtures of hexane isomers, and for the prediction and optimization of separating isotopes of cyclohexane in various organic solvents by thermodifusion.
我们将二元体系中热扩散的非平衡热力学模型扩展到多组分混合物。基本参数是各组分分子熵的差异，它可以通过三种方式之一获得：(i) 使用平衡统计力学，在恒压下作为各自平衡化学势的温度导数推导得出；(ii) 从文献中的计算机模拟获得；或(iii) 作为文献中的经验值获得。该模型用于将相关异构体或同位素的多组分混合物中的热扩散与二元混合物中的异构体/同位素效应联系起来，二元混合物中的异构体/同位素效应通常通过两种方式之一列举：(i) 作为在两种二元混合物上测量的索雷特系数的差异，每种二元混合物在共同溶剂中包含两种相关异构体/同位素之一；或(ii) 作为来自两种二元混合物的这种差异，每种二元混合物由溶解在两种相关异构体/同位素之一作为溶剂中的共同溶质组成。该模型用于估计己烷异构体纯多组分混合物中建立的浓度分布，并用于通过热扩散预测和优化在各种有机溶剂中分离环己烷同位素。
