Partial molar volumes of selected gases in some ionic liquids

The partial molar volume of a gas that is dissolved at high dilution in a solvent is required to express the influence of pressure on Henry's constant as well as to describe the volume change (expansion) of the liquid caused by the dissolved gas. The correlations of recently published experimental results for the solubility of some selected gases (CO2, Xe, CH4, CF4, H2, CO, O2) in three imidazolium-based ionic liquids (1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]), 1-n-butyl-3-methylimidazolium methyl sulfate ([bmim][CH3SO4]), and 1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([hmim][Tf2N])) determined by the synthetic method were re-evaluated by also considering the experimentally determined volumetric properties. The new evaluation does not change the published results for Henry's constants, but additionally yields reliable information on the partial molar volume of those gases in the mentioned ionic liquids at temperatures from about 293 to 413 K.