Tetramethylammonium chloride + glycerol deep eutectic solvent as separation agent for organic liquid mixtures: Assessment from experimental limiting activity coefficients

Solute retention data acquired by gas-liquid chromatography were used to determine the activity coefficients at infinite dilution for 24 organic solutes in the deep eutectic solvent (DES) consisting of tetramethylammonium chloride and glycerol in a molar ratio of 1.001:2. The organic solutes included alk-1-anes, alk-1-enes, alk-1-ynes, cycloalkanes, alkanols, alkylbenzenes, ketones, esters and heterocyclics. The measurements were undertaken at four different temperatures, viz T = (313.15, 323.15, 333.15 and 343.15) K with an estimated uncertainty of ±3.8%. From the experimental infinite dilution activity coefficient data, the values of partial molar excess enthalpy at infinite dilution were calculated using Gibbs Helmholtz relationship. Limiting selectivity and capacity values were also calculated from experimental limiting activity coefficients and compared to those of other separation agents, including other deep eutectic solvents, ionic liquids and industrial molecular agents. Results obtained in this study indicate that tetramethylammonium chloride + glycerol DES can potentially be used as an alternative solvent for nitrogen and sulphur removal from transportation fuels as well as the separation of cycloalkanes, aromatics and esters from light alkanols.