Ternary mixtures of phosphonium ionic liquids plus organic solvents plus water

Ionic liquids (ILs) and water are both potentially green solvents that are useful in a variety of extraction processes. This report presents the ternary phase diagrams and tie-line data of trihexyl(tetradecyl)phosphonium dicyanamide [P-6,P-6,P-6,P-14][DCA], phosphonium bis(2,4,4-trimethylpentyl)phosphinate [P-6,P-6,P-6,P-14][((CH3)(3)C5H8)(2)PO2], and 1-ethyl-3-methylimidazolium ethylsulfate [emim][C2H5SO4] ILs in organic solvents (ethanol, acetonitrile, toluene) and water. [P-6,P-6,P-6,P-14][DCA] and [P-6,P-6,P-6,P-14][((CH3)(3)C5H8)(2)PO2] tended to yield emulsions when combined with water and ethanol, while [emim][C2H5SO4] combined with toluene and water provided two clear phases of reasonable viscosity. The compositions of the ternary mixtures were determined to obtain the tie-lines. A noticeable difference was observed for the tie-lines of the same IL (e.g., [P-6,P-6,P-6,P-14][DCA]) with different organic solvents (ethanol and acetonitrile) and water mixtures. In all cases, the addition of ethanol eventually produced a single phase.