Description of the pVT behavior of ionic liquids and the solubility of gases in ionic liquids using an equation of state

A molecular thermodynamic model developed previously for fluids of chain-like molecules has been extended to correlate the pVT behavior of ionic liquids and the solubilities of gases such as CO2, C3H6, C3H8, C4H10 in various ionic liquids. The relative deviation between the calculated molar volume and experimental data is less than 0.2%. It is shown that this equation of state can be used to correlate the solubility of CO2 in ionic liquids with only one temperature-independent adjustable interaction parameter, and the accuracy of the correlation can be further improved using two temperature-independent adjustable parameters. The water content of ionic liquids has a large influence on the calculated results. For systems with water content lower than 0.1%, the average relative deviations of bubble point pressure are 3.14 and 4.90% using two parameters and one parameter, respectively. For systems containing C3H6, C3H8 and C4H10 two temperature dependent adjustable parameters are needed to obtain a good fit, and the corresponding deviation of the gas solubility is less than 2%, except for C3H8.