Improved COSMO-SAC for Polar Nonhydrogen Bonding Species

The activity coefficient model, COSMO-SAC, using the information from molecular solvation has been proven to provide reliable thermodynamic properties and phase behavior of mixture fluids. The accuracy of the method depend strongly on the description of interactions between surface segments. Many efforts have been made to improve such descriptions, including the temperature dependence on electronic interactions and differentiating the different types of hydrogen bonding interactions. In this work we propose a new interaction term between non-hydrogen bonding but highly polarized surfaces. The prediction accuracy in describing the vapor–liquid equilibrium of 1222 binary mixtures (15491 points, temperature range from 207.92K to 553.15K) is improved to 5.26% (AARD-P%) and 2.19% (AAD-y%) in pressure and vapor composition respectively, compared to 5.78% and 2.26% from original model. With only one additional parameter, such improvement in describing the fluid phase behavior shows the possibility in further refining COSMO-SAC model.