Solubility near the solvent's critical point

Abstract

The thermodynamic properties of dilute solutions near the critical point of the solvent — such as phase equilibria, critical lines, partial molar properties, Henry constants, K factors, and solubility — are all shown to be determined by the critical value of one thermodynamic derivative, ( ϖP/ ϖχ) V, T c , which we call the Krichevskii parameter. This parameter also governs the linear increase of In χx with density in supercritical solvents. We relate the derivative to direct correlation function integrals. We make some remarks about the nature of the divergence of total correlation function integrals. Contrary to statements we made in the literature, the divergence of the partial molar volume of the solute does not lead to an additional increase of solubility in dilute supercritical solutions, as we will show here.