Advantages of Ion-Based Mole fractions for describing Phase Equilibria in Ionic Liquids: Application to Gas Solubility

M. PAULA LONGINOTTI; JORGE L. ALVAREZ; M. LAURA JAPAS

JOURNAL OF PHYSICAL CHEMISTRY B

American Chemical Society

Lugar: Washington; Año: 2009 vol. 113 p. 3461 - 3468

1089-5647

Despite the obvious ionic character of Ionic Liquids (ILs), previous studies of phase equilibria in these media were formulated implicitely assuming a ?molecular? behavior of the ionic solvent. In this work, a more appropriate thermodynamic treatment is applied to describe the solubility of gases in ILs. According to our results, if the concentration is expressed on an ionic basis, solutions of simple gases in ILs display rather small deviations from ideal behavior in wide composition ranges, whereas  deviations are larger when the solvent is considered as a pair anion-cation. The present thermodynamic formulation also accounts for the observed solid-liquid phase equilibria of molecular and Ionic Liquids binary mixtures.