Selective Single-Step Separation of a Mixture of Three Metal Ions by a Triphasic Ionic-Liquid–Water–Ionic-Liquid Solvent Extraction System

In ac onventional solven te xtraction system, metal ions are distributed between two immiscible phases ,t ypical- ly an aqueous and an organic phase. In this paper ,t he proof-of-principle is given fo rt he distribution of metal ions between three immiscible phases, two ionic liquid phases with an aqueous phas ei nb etween them. Three-liquid-phase solven te xtraction allows separation of am ixture of three metal ions in as ingl es tep, whereas at least two steps are re- quire dt os eparate three metals in the case of two-liquid- phas es olvent extraction. In the triphasic system, the lower organic phas ei sc omprised of the ionic liquid betainium- or cholin eb is(trifluoromethylsulfonyl)imide, whereas the upper organic phas ei sc omprised of the ionic liquid trihexyl(tetra- decyl)phosphonium bis(trifluoromethylsulfonyl)imide. The triphasic system was used for the separation of am ixture of tin(II) ,y ttrium(III), and scandium(III) ions.