Applications of Near-Critical Dilute-Solution Thermodynamics

Abstract

Much of the thermodynamics of dilute solutions near the solvent's critical point is governed by a single thermodynamic derivative known as the Krichevskii parameter. This parameter manifests itself in some linear asymptotic relationships that describe the behavior of solute Henry's constants and infinite-dilution K-factors in the vicinity of the solvent's critical point. This paper reviews the application of these asymptotic relationships to practical thermodynamic calculations. Successful correlations have been produced for Henry's constants and K-factors. Application to apparent molar properties is discussed, and an explanation is given for its quantitative inadequacy. The Henry's constant relationship has been extended to describe the solubility of solids in supercritical fluids; current limitations and future prospects are discussed for this application. Finally, a new linear relationship is derived for the capacity factor in supercritical fluid chromatography and applied to some data from the literature.