COSMO-descriptor based computer-aided ionic liquid design for separation processes. Part I: Modified group contribution methodology for predicting surface charge density profile of ionic liquids

When applying COSMO-based models in Computer-Aided Ionic Liquid Design (CAILD), the generation of surface charge density profiles (sigma-profiles) and cavity volumes (V-COSMO) of ILs is particularly important but too computationally expensive with quantum chemical calculations. In this work, a modified group contribution methodology, the COSMO-GC-IL method, is proposed for quick prediction of IL sigma-profiles and V-COSMO based on sigma-profiles of IL groups in their reference states (COSMO descriptors), together with two modification parameters (stretch and translation parameters). The influence of molecular environment on target groups can be well described and IL isomers are thereby distinguishable. To verify the method, a profiles and V-COSMO generated from the present method and from the DMol(3) database are employed to calculate activity coefficients of 28,644 binary systems and 3410 liquid-liquid equilibria of ternary mixtures. Their close results in most cases demonstrate the reliability of the COSMO-GC-IL method. (C) 2016 Elsevier Ltd. All rights reserved.