A modified Wilson model for the calculation of vapour + liquid equilibrium of aqueous polymer + salt solutions

The Wilson model for non-electrolytes is extended to represent the excess Gibbs free energy of aqueous (polymer + electrolyte) solutions. The proposed extension is an integration of the electrolyte Wilson model [E. Zhao, M. Yu, R.E. Sauvé, M. Khoshkbarchi, Fluid Phase equilibr. 173 (2000) 161-175] and the polymer Wilson model [R. Sadeghi, J. Chem. Thermodyn. 37 (2005) 55-60]. The model provides a versatile and flexible thermodynamic framework for both correlating and predicting the phase equilibrium of electrolyte solutions, polymer solutions and complex systems containing both electrolytes and polymers. The utility of the model is demonstrated with successful representation of (vapour + liquid) equilibrium of several PEG or PPG-salt-H2O systems at different polymer molar masses.