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
(Rk and Qk) of IL groups; the experimental phase
equilibrium data of the systems containing ILs were used to get the
unknown group binary interaction parameters (anm and amn). 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.