Separation of binary mixtures hexane/hex-1-ene, cyclohexane/cyclohexene and ethylbenzene/styrene based on gamma infinity data measurements

Abstract The activity coefficients γ 13 ∞ at infinite dilution for 64 solutes were determined in the 1-(3-hydroxypropyl)-3-methylimidazolium dicyanamide, [N-C3OHMIM][DCA] and 58 solutes in (3-hydroxypropyl)-1-methylmorpholinium dicyanamide, [N-C3OHMMor][DCA] using the gas-liquid chromatography technique. Measurements were undertaken at six temperatures, in 10 K intervals, in the range of (298.15–368.15) K. The solutes studied included both non-polar and polar compounds, as alkanes, alkenes, and alkynes, as well as aromatic hydrocarbons, alcohols, water, ethers, ketones, acetonitrile, pyridine, 1-nitropropane, thiophene, and esters. Density, ρ, measurements for a range of temperatures (298.15–368.15) K for the synthesized, new ionic liquids (ILs) were also undertaken at pressure, p = 101 kPa. The gas-liquid partition coefficients, K L at infinite dilution, and the fundamental thermodynamic functions, partial molar excess Gibbs energy, enthalpy and entropy at infinite dilution were calculated from the experimental data measurements. The values of selectivity and capacity for three separation cases, viz. hexane/hex-1-ene, cyclohexane/cyclohexene, and ethylbenzene/styrene were calculated from γ 13 ∞ values and compared to literature for imidazolium-based, morfolinium-based, or dicyanamide-based, ILs. The results from the study indicate that [N-C3OHMIM][DCA] has large selectivity values for all three of the separation cases studied and that [N-C3OHMMor][DCA] has the largest selectivity ever noted for cyclohexane/cyclohexene, and ethylbenzene/styrene separation processes.