Thermodynamics and activity coefficients at infinite dilution for organic compounds in the ionic liquid 1-hexyl-3-methylimidazolium chloride

The activity coefficients at infinite dilution,gamma(infinity)(i), for 33 solutes, including alkanes, cycloalkanes, alkenes, aromatic hydrocarbons, acetonitrile, acetone, tetrahydrofuran, ethyl acetate, 1,4-dioxane, chloromethanes, alcohols in the ionic liquid 1-hexyl-3-methylimidazolium chloride, [HMIM][Cl], were determined by gas-liquid chromatography at temperatures range of (313.15-363.15) K. The gas-liquid partition coefficients, K-L were calculated for all solutes. The densities of [HMIM][Cl] were measured at the temperature range from 313.15 K to 363.15 K. The values of the partial molar excess enthalpies at infinite dilution (H-i(-E,infinity)) were derived fromthe temperature dependence of the gamma(infinity)(i) values. The entropies (TrefSi-E,infinity) and Gibbs energies (G(i)(-E,infinity)) of organic solutes in [HMIM][Cl] at a reference temperatureT(ref) = 298.15 K were also calculated from the gamma(infinity)(i) values. The Hildebrand's solubility parameters of the IL [HMIM][Cl] were also determined by the regular solution theory (RST) combined with Flory "combinatorial'' equation. The values of selectivity and capacity for n-hexane(i)/benzene(j), cyclohexane(i)/benzene(j) were calculated from gamma(infinity)(i) and compared to literature values for [HMIM]-based or [Cl]-based ILs for the same separation problems. (C) 2018 Elsevier Ltd.