Application of a group contribution equation of state to model the phase behavior of mixtures containing alkanes and ionic liquids

In this work, the group contribution equation of state (GC-EoS) of Skjold-Jørgensen was used to model the phase behavior of mixtures of alkanes with different members of the homologous family 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [x-Mpyr][NTf2] ionic liquids. Pure group parameters for the ionic liquid functional group (MpyrNTf2) and interaction parameters between this group and the paraffin main group (sub-groups CH3 and CH2) were obtained from activity coefficients at infinite dilution found in literature for binary mixture {alkane + [x-Mpyr][NTf2] ionic liquid}. The GC-EoS of Skjold-Jørgensen, extended with these new parameters, was applied to predict with satisfactory results the phase behavior of binary mixtures {alkane + [x-Mpyr][NTf2]}. In order to evaluate the GC-EoS performance in the prediction of liquid–liquid equilibria (LLE), experimental LLE data for binary mixtures {hexane, or heptane, or octane, or nonane, or decane +1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [BMpyr][NTf2]} were determined from T = (293.15 to 333.15) K