An ionic liquid extractant dissolved in an ionic liquid diluent for selective extraction of Li(I) from salt lakes

An efficient recovery of lithium (Li(I)) from salt lakes is currently a challenging issue. Herein, we report a feasible extraction of Li(I) from a simulated salt lake solution using a novel extraction system, in which a functionalized ionic liquid (FIL) is dissolved in a different ionic liquid diluent. As a functional extractant, 3-methyl-1-octylimidazolium thenoyltrifluoroacetone [Omim][TTA] was successfully prepared in a simple way and its extraction performance for Li(I) was evaluated. The effects of pH and metal concentration on extraction, as well as the stripping property, were systematically investigated. It was found that the FIL could effectively act as the extractant of Li(I) over a wide range of pH, and even under acidic conditions. The extraction ability of the FIL was markedly enhanced by its use in an ionic liquid diluent. The obtained results demonstrated that Li(I) was extracted from the aqueous solution into the ionic liquids with a high extraction efficiency even in a five-cycle reusability test. Furthermore, using a simulated salt lake solution, Li(I) was selectively extracted with a high separation factor of 227 over Na(I), whereas Na(I) and K(I) remained in the aqueous feed solution. [Display omitted] •Li(I) is extracted by [Omim][TTA] even under acidic conditions.•The extraction ability of [Omim][TTA] is enhanced in an ionic liquid diluent.•The extraction mechanism of [Omim][TTA] with Li(I) is elucidated.•Li(I) is selectively extracted from high concentrations of interfering ions.•Li(I) is selectively extracted with a high separation factor of 227 over Na(I).