Abstract

The popular equation of state of Peng and Robinson has been applied to correlate the liquid+vapor equilibrium in binary mixtures containing supercritical carbon dioxide. The classical van der Waals mixing rules and a general mixing rule proposed by the authors (Valderrama et al., 2000), have been used Experimental data obtained from the literature for four mixtures have been selected for analysis. The necessary interaction parameters have been determined by minimizing the deviations between the experimental concentration and that predicted by the model for the solute concentration in the gas phase. This work allows concluding on the advantages, disadvantages and the expected accuracy when cubic equations of state such as that of Peng and Robinson are used The results also allow to clarify some misleading arguments usually found in the literature with respect to the accuracy of these cubic equations when are applied to highly asymmetric mixtures such as those found in supercritical extraction processes.