A CUBIC EQUATION OF STATE - RELATION BETWEEN BINARY INTERACTION PARAMETERS AND INFINITE DILUTION ACTIVITY-COEFFICIENTS

A modified Redlich-Kwong cubic equation of state (CEOS) is applied to the calculation of phase equilibria for highly non-ideal systems. Owin g to the new mixing rule used in the CEOS, the physical meaning of the binary interaction parameters in the CEOS can be explained in terms o f infinite dilution activity coefficients. Equations relating the bina ry interaction parameters in the equation of state to the infinite dil ution activity coefficients are presented. A robust technique is propo sed for obtaining the interaction parameters without regressing PTxy d ata. The equation of state with the binary interaction parameters deri ved from the infinite dilution activity coefficients is suitable for t he process design of separation processes, especially for environmenta l concerns, which require prediction of high purity products. The resu lts of calculations are compared with experimental PTxy data.