Gas–liquid equilibrium modeling of mixtures containing supercritical carbon dioxide and an ionic liquid

Gas–liquid equilibrium in mixtures containing supercritical carbon dioxide and an ionic liquid has been modeled using the Peng–Robinson equation of state and the interesting modification proposed by Kwak and Mansoori. The proposal is based on statistical–mechanical arguments and on the fact that mixing rules are for constants of an equation of state and not for functions such as the alpha expression that makes the attractive term temperature dependent. Experimental data for mixtures containing carbon dioxide and ionic liquids were obtained from literature sources and the adjustable parameters of the mixing rules were found by minimizing the errors between predicted and experimental bubble pressure. Results were compared with experimental data and with results of other classical mixing rules, such as the proposal of Wong and Sandler. The deviations in correlating gas–liquid equilibrium found with the model Peng–Robinson/Kwak–Mansoori are lower in general than the results obtained with other models.

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► GLE in supercritical CO2 + ionic liquid mixtures are modeled using modern mixing rules.
► The Kwak–Mansoori and the Wong–Sandler the mixing rules provide good correlation.
► The three interaction parameters of the mixing rules give the models good flexibility.
► For the systems studied the Kwak–Mansoori model gave better correlation.
► Deviations with Kwak–Mansoori are lower that other models used in the literature.