Liquid extraction of polyhydric alcohols from water using [A336][SCN] as a solvent

Highlights: • [A336][SCN] was studied as a solvent to extract polyhydric alcohols from water. • LLE data for ternary systems were determined at T = 303.2 K and atmospheric pressure. • The NRTL model was applied to fit the LLE data with a good accuracy. • Selectivity and solute distribution ratio were obtained and compared with literature. • [A336][SCN] was a promising solvent to separate polyhydric alcohols and water. - Abstract: This work demonstrated the possibility of hydrophobic ionic liquid tricaprylmethylammonium thiocyanate ([A336][SCN]) as a solvent in the separation by extraction of polyhydric alcohols from their mixtures with water. The knowledge of (liquid + liquid) equilibrium (LLE) of these mixtures is essential for the design of the extraction process. For this reason, the LLE data of the ternary systems {[A336][SCN] + water + glycerol, or ethylene glycol, or 1,2-propanediol, or 1,3-propanediol} were determined at T = 303.2 K and atmospheric pressure. The reliability of the tie-lines data was ascertained by applying the Othmer–Tobias equation, and the non-random two liquid (NRTL) model used to fit the experimental LLE data. The effectiveness of the extraction of polyhydric alcohols from water was evaluated using the solute distribution ratio and the selectivity. The extraction capability of [A336][SCN] was compared with that of other ILs. The results indicated that the [A336][SCN] was suitable for use as a solvent in (liquid + liquid) extraction of polyhydric alcohols from water