A GROUP-CONTRIBUTION EQUATION OF STATE FOR ASSOCIATING MIXTURES

In the present work a group contribution-associating-equation of state (GCA-EOS) is developed for the modeling of phase equilibria found in the near critical fluid extraction and dehydration of oxygenated compo unds from aqueous solutions. The new equation of state is obtained by the inclusion of a 'group' contribution associating term to the GC-EOS model. The definition of a unique hydroxyl group to represent the ass ociation effect of hydrogen bonding in water and alcohols, greatly sim plifies the extension of the model to multicomponent mixtures. This ap proach has been applied to determine the parameters for a common hydro xyl group for water, primary and secondary alcohols. On this basis, re vised group and binary interaction dispersive parameters for water, pr imary and secondary alcohols, alkane groups, light hydrocarbons and CO 2 have been determined. Model predictions for binary and ternary data are presented.