Irregular ionic lattice model for gas solubilities in ionic liquids

The irregular ionic lattice model (IILM) is applied to predict the vapor pressures and solubilities of carbon dioxide dissolved in 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim] [PF6]) and in 1-n-octyl-3-methylimidazolium tetrafluoroborate ([C8mim] [BF4]) ionic liquids at temperatures ranging from 298.15 to 333.15 K. The model contains only two parameters; they are shown to be independent of an arbitrarily chosen reference state. The parameters show a slight dependence on temperature, but this dependence is ignored in computations to demonstrate the rigor of the IILM in predicting CO2 solubility at high and low pressures at various temperatures. Model predictions are compared against the experimental data of Anthony et al. (J. Phys. Chem. B 2002, 106, 7315) and of Blanchard et al. (J. Phys. Chem. B 2001, 105, 2437). The usefulness of the model is in predicting CO2 solubilities at temperatures and pressures where experimental data are unavailable.