Choline chloride based deep eutectic solvents as extraction media for separation of n-hexane-ethanol mixture

Two different choline chloride based deep eutectic solvents (DES) were tested for the separation of azeotropic mixture of n-hexane and ethanol via liquid-liquid extraction. The simplest mixtures of choline chloride with dibasic acids: oxalic (DES1) or malonic (DES2) with molar ratio 1:1 were used. The selected DESs were characterized by differential scanning calorimetry (DSC). Extraction experiments were conducted with pseudo-ternary mixtures n-hexane-ethanol-DES. Tie-lines were obtained at temperatures 293.15 K, 313.15 K and atmospheric pressure. The extraction performance of DES was characterized with solute distribution coefficients and values of selectively for ethanol. It has been shown that the most successful component for the separation of a mixture of n-hexane-ethanol is water. It was found that DES1 is more effective then DES2 for extraction of ethanol. The higher efficiency of separation of DES as compared to conventional ionic liquids (IL) makes it possible to consider them as an alternative promising solution in the separation of multicomponent mixtures. Experimental data was fitted using the nonrandom two liquids (NRTL) model.