Predicting Ionic Liquids’ Second-Order Derivative Properties based on a Combination of SAFT-γ EoS and a GC Technique

Considering the high number of ionic liquids (ILs) and the impracticability of laboratory measurements for all properties of ILs, applying theoretical methods to predict the properties of this large family of ILs can be very helpful. In the present research, the thermophysical properties of ILs are predicted by a combination of statistical associating fluid theory and the group contribution concept (SAFT-γ GC EoS). The studied ionic liquids are 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([emim][CF3SO3]), 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([bmim][CF3SO3]), 1,3-dimethylimidazolium methylsulfate ([mmim][MeSO4]), 1-ethyl-3-methylimidazolium methylsulfate ([emim][MeSO4]), 1-butyl-3-methylimidazolium methylsulfate ([bmim][MeSO4]), 1-ethyl-3-methylimidazolium methanesulfonate ([emim][MeSO3]) and 1-ethyl-3-methylimidazolium ethylsulfate ([emim][EtSO4]). The thermophysical properties including the coefficient of thermal expansion, coefficient of thermal pressure, coefficient of isentropic compressibility, coefficient of isothermal compressibility, speed of sound, isochoric and isobaric heat capacities are estimated within broad ranges of pressure and temperature (0.1-60 MPa and 273-413 K). The comparison among the SAFT-γ predictions and some available experimental data shows good ability of SAFT-γ EoS to estimate the second-order derivative thermophysical properties of ILs.