Measurement of Activity Coefficients at Infinite Dilution for Various Organic Solutes in Deep Eutectic Solvent (1-Butyl-2,3-dimethylimidazolium Chloride plus Ethylene Glycol) at Different Temperatures

Activity coefficients at infinite dilution (gamma 13 infinity) for organic solutes in deep eutectic solvent (DES) prepared by {1-butyl-2,3-dimethylimidazolium chloride (BDMIM Cl) + ethylene glycol (EG)} at a molar ratio of 1:3 have been measured using the gas-liquid chromatographic method (GLC). The thermal stability of the entrainer was determined by the thermogravimetric analyzer. The measurements were carried out in the temperature range of T = (313.15 to 343.15) K and at atmospheric pressure. The values of the partial molar excess enthalpies at infinite dilution (H1E,infinity) were derived from the temperature dependence of the gamma 13 infinity infinity values. The entropies (Tref Delta S1E,infinity) and Gibbs energies (Delta G1E,infinity) of organic solutes at a reference temperature Tref = 323.15 K were also calculated from the gamma 13 infinity values. These excess thermodynamic functions were calculated to further explain the intermolecular interactions occurring between the volatile organic solvents and the prepared deep eutectic solvent. Important separation parameters such as selectivities (Sij infinity) and capacities (Kj infinity) at infinite dilution were computed from the activity coefficients at infinite dilution data at T = 313.15 K. Selectivity and capacity data were calculated for the industrial mixtures such as cyclohexane/benzene, hexane/thiophene, cyclohexane/ethanol. There results were compared to the literature data comprising deep eutectic solvents and ILs with the cation of 1-butyl-3-methylimidazolium. The investigated solvent was found suitable to separate azeotropes formed by alkanes/alcohols.