NEAR-CRITICAL PHASE-BEHAVIOR OF DILUTE MIXTURES

Predictions of the limiting phase behaviour of dilute mixtures of n-decane, n-tetradecane, n-octadecane, and n-docosane with n-hexane in the highly compressible region close to the critical point of n-hexane are presented. The predictions are based on a classical Taylor expansion of the Helmholtz energy about the critical point of the solvent [1, 2] and make use of the measured critical properties of the dilute mixtures. The importance of the Krichevskii parameter as a key factor influencing the limiting phase behaviour of dilute mixtures is demonstrated in the case of infinite dilution partition coefficients as well as solute partial molar volumes, and the link to a statistical mechanical description is made.