ABSTRACT
This chapter describes the limitations of Task-specific” ionic liquids (TSILs) that may impede further progress and outlines promising areas for future work. It shows while much has been accomplished, significant additional effort will be required if TSILs are to achieve their full potential as media for metal ion extraction. TSILs represent an increasingly important subclass of ionic liquids consisting of a conventional IL to which is appended a functional group chosen to impart the solvent with specific physicochemical, catalytic, or solute-binding properties. The separation of metal ions using TSILs commonly involves liquid–liquid extraction, in which an aqueous solution containing the ion of interest and one or more other metal ions is contacted with an immiscible liquid in which is contained a metal ion-selective organic extractant. A variety of other extractant fragments have also been incorporated into TSILs. The anion of any of several organophosphorus acids has also served as the basis for a TSIL.
