Prediction of miscibility gaps in water/ether mixtures using COSMO-SAC model

The various versions of COSMO-SAC model are used to examine the liquid-liquid equilibrium of 9 ether/water binary mixtures. It is found that the original COSMO-SAC (2002) model is more accurate in describing the composition of the water-rich phase, while the recently revised COSMO-SAC (2010) model is more accurate in the ether-rich phase. The absolute average error in the predicted ether composition is found to be 85% in the water-rich phase and 17% in the ether-rich phase using COSMO-SAC (2002). The corresponding errors are 218% and 1.5% when COSMO-SAC (2010) is used. When the hydrogen bonding interactions are re-parameterized against the ether/water LLE data, the errors can be reduced significantly in both phases to 44% and 1.4%. This new parameterization, referred to as COSMO-SAC (2010f), also provides accurate predictions of the mutual solubility of the PROGLYDE DMM/water mixture at temperatures from 283. K to 353. K.