Phase Behavior of Ionic Liquid-Based Aqueous Two-Phase Systems

Abstract

As an environmentally friendly separation medium, the ionic liquid (IL)-based aqueous two-phase system (ATPS) is attracting long-term attention from a growing number of scientists and engineers. Phase equilibrium data of IL-based ATPSs are an important basis for the design and optimization of chemical reactions and separation processes involving ILs. This article provides the recent significant progress that has been made in the field and highlights the possible directions of future developments. The effects of each component (such as salting-out agents and ILs) on the phase behavior of IL-based ATPSs are summarized and discussed in detail. We mainly focus on the phase behavior of ATPSs by using ILs, expecting to provide meaningful and valuable information that may promote further research and application.

What Can Be Learned from the Partitioning Behavior of Proteins in Aqueous Two-Phase Systems?

“…It is important to emphasize here that a defining feature that allows the classification of a given system as an ATPS is the fact that although the phases are immiscible and differ in their solvent properties, each of the phases contains well over 80% water on a molal basis. Therefore, although two-phase systems can be formed by water, (hydrophobic) ionic liquids, and aqueous solutions of inorganic salts [ 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 ], or by ionic liquids and polymers [ 74 , 75 , 76 , 77 ], ionic liquids and surfactants [ 78 , 79 ], and water and water-miscible organic solvent (e.g., ethanol) with inorganic salt additives [ 80 , 81 , 82 , 83 , 84 ], such two-phase systems cannot be classified as ATPSs, as, strictly speaking, in these cases, both resulting phases cannot be considered aqueous.…”