Separation of binary mixtures based on gamma infinity data using [EMIM][TCM] ionic liquid and modelling of thermodynamic functions

Abstract

The measurements of activity coefficients γ13∞ at infinite dilution for 64 solutes including water is presented for 1-ethyl-3-methylimidazolium tricyanomethanide, [EMIM][TCM] ionic liquid (IL). The data obtained by gas-liquid chromatography at six temperatures at 10K intervals in range of (318.15 to 368.15) K are presented for non-polar and polar solutes as alkanes, alkenes and alkynes as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters. The comparison of γ13∞ at one temperature, T=328.15K for selected solutes in ionic liquids (ILs) with [EMIM]+ cation and [TCM]−, [DCA]−, [TCB]− and [SCN]− -anions is presented. The gas-liquid partition coefficients, KL at infinite dilution and the fundamental thermodynamic functions, the partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution are calculated for all solutes. The values of selectivity and capacity for three separation problems such as hexane/hex-1-ene, cyclohexane/cyclohexene and methylbenzene/styrene are calculated from γ13∞ and compared to literature values for [EMIM]-based or [TCM]-based ILs for the same separation problems. The data presented here shows that [EMIM][TCM] reveals large selectivity 2.35, 2.24, and 2.01 in three of discussed separation problems, hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene. The comparison to the measured earlier [TCM]-based ILs shows the lowest capacity for the hexane/hex-1-ene separation problem. The Abraham solvation parameter model is also discussed. Present study discusses the intermolecular interactions of the chosen IL and solutes and may be of considerable importance for selection of optimum entrainer for the desired three separation processes.