Study of the pseudo-ternary aqueous two-phase systems of deep eutectic solvent (choline chloride:sugars) + K2HPO4 + water

Abstract

Deep eutectic solvents (DES) are a new type of solvents that share some characteristics with Ionic Liquids while being cheaper, easier to prepare and, in some case, more readily biodegradable. This work reports a study on the Liquid-liquid Equilibria (LLE) of aqueous two-phase systems composed by DES + K2HPO4 + water at 298.15 K. Various DES using choline chloride as hydrogen bond acceptor (HBA), and sugars as hydrogen bond donor (HBD), were prepared at several different proportions. An approach based on thermogravimetric analysis is here proposed to quantify the phase's components. The results show that the hydrogen bonds of DES are disrupted in aqueous solutions, leading to a differential partition of the HBA and HBD between the two phases, and to be coherent a quaternary ATPS must be considered. The NRTL model was used to describe the experimental LLE data with a low mean deviation. These systems were applied to Gallic Acid partition showing good extraction levels.