SAFT-γ Equation of State to Model the High-Pressure Densities of Imidozalium-Based Ionic Liquids with Cyano-Functionalized Anions

A group contribution (GC) procedure, on the basis of SAFT-γ equation, is extended to cover new families of imidazolium-based ionic liquids (ILs), with either the [SCN], [N(CN)۲], [C(CN)۳] or [B(CN)۴] anions. In this GC model, IL system is decomposed into the chemical groups of the cationic head, CH۳, CH۲, and the anion. The anion-cationic head association interactions were taken into consideration by introducing appropriate association sites on the cation head and the anion groups. The IL groups of the SAFT-γ equation were fit to IL density data at temperatures from ۲۶۲ to ۴۱۲ K. Pressures varied up to ۲۰۰ MPa. Sixteen anion group parameters and eight parameters of association amongst the cationic head and the anions were determined. Finally, the strength of SAFT-γ in predictions was investigated by estimating the density of ILs, for some ILs which were not considered in the fitting process. The average absolute relative deviations in density predictions did not exceed ۱.۴%.