(742a) Liquid-Liquid Phase Separation of Ionic Liquids By Water Addition (Experiment and Simulation)

Ionic liquids have attracted significant interest in the fields of separation and catalysis as a potential replacement for organic solvents. A common practice is to utilize ionic liquids as a co-solvent, and recent research has explored using aqueous biphasic ionic liquid systems as a green approach. It is, therefore, of interest to investigate the phase behavior of ionic liquid and water ternary mixtures.

This work probes the mutual miscibility of 1-ethy-3-methylimidazolum [C₂mim]-based ionic liquids possessing different anions including: bis(trifluoromethylsulfonyl)imide [Tf₂N], acetate [OAc], and chloride [Cl]. Over a wide range of concentrations, ionic liquid mixtures were observed to form a homogeneous liquid phase or a solid-liquid solution. Molecular dynamic (MD) simulations predicted the phase separation of miscible ionic liquids binary mixtures containing [C₂mim][Tf₂N] + [C₂mim][OAc] and [C₂mim][Tf₂N] + [C₂mim][Cl] by addition of water at room temperature. Experimental measurements verified the MD predictions and, additionally, determined the concentrations in each liquid phase.