Parameterization of COSMO-RS model for ionic liquids

Abstract

The adjustable parameters in the popular conductor-like screening model for real solvents (COSMO-RS) within the Amsterdam density functional (ADF) framework have been re-optimized to fit for the systems containing ionic liquids (ILs). To get the optimal values of misfit energy constant a′, hydrogen bond coefficient chb and effective contact surface area of a segment aeff, 2283 activity coefficient data points at infinite dilution and 1433 CO2 solubility data points exhaustively collected from references were used as training set. The average relative deviations (ARDs) of activity coefficients at infinite dilution and CO2 solubility between experimental data and predicted values are 32.22% and 17.61%, respectively, both of which are significantly lower than the original COSMO-RS versions. Predictions for other activity coefficients of solutes in ILs, solubility data of CO2 in pure ILs and the binary mixtures of ILs at either high or low temperatures, and vapor–liquid equilibrium (VLE) for binary systems involving ILs have also been performed to demonstrate the validity of the parameterization of COSMO-RS model for ILs. The results showed that the predicted results by COSMO-RS model with the new optimized parameters are in much better agreement with experimental data than those by the original versions over a wide temperature and pressure range. The COSMO-RS model for ILs presented in this work improves the prediction accuracy of thermodynamic properties for the systems containing ILs, which is always highly desirable for general chemical engineers.