UNIFAC Model for Ionic Liquids. 2. Revision and Extension

Ionic liquids (ILs) as separating agents have been extensively studied in chemical separation processes. For IL-containing systems, the UNIFAC model for ILs (i.e., UNIFAC-Lei model) has become a popular group contribution approach to predict phase equilibrium behavior. Since the UNIFAC-Lei model was established in 2009, our group has continued to extend and revise this model because the accurate prediction and application scope of this model depend on the quality and size of the parameter matrix besides the statements and hypothesis assumed for the model. Thus, this work is focused on revising and extending the UNIFAC-Lei parameter matrix through plentiful and accurate experimental data. In this work, four new groups ([MIM]­[DBP], [MIM]­[TCM], [MIM]­[DCA], and [PYM]­[TCM]) were added, 63 pairs of new parameters were extended, and eight pairs of old parameters were revised. The COSMO calculation was used to get the unknown group surface area and volume parameters (R_k and Q_k) of IL groups; the experimental phase equilibrium data of the systems containing ILs were used to get the unknown group binary interaction parameters (a_nm and a_mn). The comparison of the UNIFAC-Lei predicted vapor–liquid equilibrium values with experimental data indicates that the UNIFAC-Lei model can provide relatively satisfactory phase equilibrium prediction for IL-containing systems.