Solvent pre-selection for binary mixtures based on the infinite dilution at activity coefficients in deep eutectic solvent: Tetraethylammonium chloride + Ethylene glycol

Abstract The values of activity coefficient at infinite dilution () were reported of 27 solutes in the tetraethylammonium chloride + ethylene glycol deep eutectic solvent at a certain molar ratio 1:2 by inverse gas chromatography (IGC) method at intervals of 10 K from 303.15 to 333.15 K. Then the measured values were used to determine the thermodynamic functions ( and ). The values of selectivity () and capacity () for five extraction problems (e.g. heptane/toluene, benzene/methanol, heptane/thiophene, acetone/ethanol, cyclohexane/benzene, and cyclohexane/ethanol.) were calculated from experimental values as well as compared to literature values of other solvents for the same separation problems. The results indicated that the studied DES is a potential extractant for separation cyclohexane/ethanol and heptane/thiophene problems. The Flory-Huggins interaction parameters () and the gas-to-liquid partition coefficients () were used to evaluate the miscibility between DES and organic probes, and the results showed that alcohols have the best solubility in tested DES. Additionally, the Hildebrand solubility parameters () for tested DES were calculated, and the values of decreased with the increase of temperature.