PC-SAFT predictions on mixtures of 1-alkyl-3methylimidazolium-bis(trifluroromethanesulphonyl)amide with hydrocarbons, alcohols and aqueous systems using a correlative based binary interaction parameter

Abstract

The current work proposes a PC-SAFT (perturbed chain-statistical associated fluid theory) based temperature independent binary interaction parameter (kij) expressed as a function of carbon atoms in a solute molecule and chain length of cation for the ionic liquid (IL), 1-alkyl-3methylimidazaolium bis(trifluroromethanesulphonyl)amide ([Cnmim][Tf2N]). A total of nine binary mixtures comprising of mixtures of ILs with hydrocarbons, alcohol and water were investigated in this study. Initially the PC-SAFT parameters from liquid densities and vapor pressures along with the correlated binary interaction parameter were used to predict the vapor liquid equilibria (VLE) for nine systems. The absolute average deviation (AAD) for the three systems was found to be 3%, 4% and 3% respectively. Further the effect of alkyl chain length of cation, alcohol, hydrocarbon and temperature were also studied and compared using the correlated binary interaction parameter. In comparison with the results obtained from COSMO-RS, UNIFAC and PC-SAFT–UNIFAC methods, the PC-SAFT parameters with the correlated interaction parameter gave an average AAD of 4%.This is lesser as compared to the COSMO-RS model (∼9%) and the PC-SAFT version (∼5%) which uses liquid density to regress the parameters. The transferability of the correlated binary interaction parameters have also been demonstrated on another system namely [C4mim][BF4]–alcohol system albeit with limited success.