Application of MOSCED To Predict Limiting Activity Coefficients, Hydration Free Energies, Henry’s Constants, Octanol/Water Partition Coefficients, and Isobaric Azeotropic Vapor–Liquid Equilibrium

Modified Separation of Cohesive Energy Density (MOSCED) is a solubility parameter-based method to predict limiting activity coefficients. In addition to making quantitative predictions, MOSCED may additionally be used to understand the underlying molecular-level driving forces for intuitive solvent selection and formulation. A major improvement of MOSCED over similar solubility parameter methods is that it splits the association term. We show by example how this change allows MOSCED to better model the molecular interactions of associating fluids. While parametrized to predict limiting activity coefficients, we demonstrate the ability to predict hydration-free energies, Henry’s constants in water, and octanol/water partition coefficients. We focus on water as MOSCED was previously found to perform substantially worse when water was the solvent. Comparison is made to molecular simulation and mod-UNIFAC, and we find for the studied reference set that predictions with MOSCED were in better agreement with experimental data. Comparison to mod-UNIFAC was additionally made to model binary isobaric azeotropic vapor–liquid equilibrium. Overall, for these nonideal systems, the quantitative agreement with experiment is better with mod-UNIFAC, although the difference with MOSCED is relatively small. An interactive software suite (MOSCED-CAD) has also been developed to calculate the properties described in the present study, in addition to binary interaction parameters for the Wilson and the nonrandom two-liquid (NRTL) equations for use in a process simulator.