Improved Prediction of Phase Behaviors of Ionic Liquid Solutions with the Consideration of Directional Hydrogen Bonding Interactions

2020-02-13T22:44:57Z (GMT) by Chun-Kai Chang Shiang-Tai Lin
The consideration of directional hydrogen bonding in the COSMO-SAC model based on the minima in the molecular electrostatic potential has been shown to significantly improve the description of solvation properties of a wide variety of associating fluids containing nonionic species. In this work, we report the use of this method for the prediction of thermodynamic properties and phase equilibria of ionic liquid solutions, including infinite dilution activity coefficients (IDAC), osmotic coefficients (ϕ), liquid–liquid equilibria (LLE), and vapor–liquid equilibria (VLE). When compared to the previous version of the COSMO-SAC model without the consideration of directional hydrogen bonding, the new method, which has a tendency giving more polar σ-profiles, improves the prediction of osmotic coefficients and VLE by 10% (26% AARD, 1372 data points) and 5% (32% AARD, 1645 data points), respectively. Comparable results are observed from the two methods in LLE [0.2 and 0.1 root mean square (rms) error for ionic liquid-rich and solvent-rich regions, respectively, with 2876 data points] and IDAC (0.71 rms error with 3555 data points) predictions.