Extension of COSMO-SAC Solvation Model for Electrolytes

COSMO-based activity coefficient models such as COSMO-SAC (Conductor-like screening model-segment activity coefficient) have been shown to be relatively successful predictive models for molecular systems. In this study we present an extension of COSMO-SAC to electrolytes (eCOSMO-SAC) which combines the COSMO-SAC term for short range molecule-molecule, molecule-ion and ion-ion interactions with the extended symmetric Pitzer-Debye-Hückel term for long range ion-ion interactions. The extension recognizes that like-ion repulsion and local electroneutrality govern the surface segment contacts, and introduces a dual sigma profile concept for electrolyte systems. The eCOSMO-SAC formulation predicts activity coefficients of several representative electrolyte systems and the results compare favorably with those generated from the eNRTL model.