Thermodynamics of gas solubility in mixed solvents

Abstract

This work considers the thermodynamic description of a liquid solution containing one gaseous solute and two or more miscible liquid solvents. For the solvents, the reference fugacity is that of the pure components but for the solute, the reference state fugacity is set equal to Henry's constant in one of the solvents; thus, the unsymmetric convention for activity coefficients is employed. A transformation of Wohl's method is used to predict the properties of a multicomponent solution from information on the binary pairs formed by the solution's components. Equations are derived for the case where the properties of each binary pair can be described by a one-term Margules equation; therefore, the results presented here are applicable only to simple, nonpolar solutions. However, the method can be extended to higher-order equations, if sufficient experimental information is available to justify the use of additional parameters. In nonpolar systems, the logarithm of the gas solubility at low pressures is, to a good approximation, a linear function of the solvent composition. © 1964, American Chemical Society. All rights reserved.