A group contribution model for activity coefficients in associating solutions

A group contribution model is presented for the prediction of activity coefficients in associating mixtures. The new model adds an association term to the traditional UNIFAC residual and combinatorial contributions to the activity coefficients. The association term is based on Wertheim’s theory for fluids with highly directed attractive forces, as applied in the SAFT equation, and it follows the group contribution approach proposed by Gros et al. in the GCA-EOS model. Good predictions of both, vaporliquid and liquid-liquid equilibria are achieved in the whole concentration range, with a single set of group interaction parameters