Ionic Liquids: How Far Do they Extend the Potential of Solvent Extraction of f-Elements?

Applicability of room temperature liquids (RTILs) as diluents in the solvent extraction of f-elements is reviewed. Characteristics of selected RTILs, important for such an application, are gathered. Properties tabulated are the melting and freezing points, density, mutual solubility with water, viscosity, surface tension, specific conductivity, and radiation stability. Properties such as environmental compatibility, toxicity, chemical and thermal stability, biodegradability, and chemical degradability imply that RTILs are not harmless to the environment or to work safety. The extraction efficiency and mechanism in systems involving RTILs is described, discussed, and compared with systems involving molecular diluents. Particularly assessed is the extraction of nitric acid by RTILs alone and TBP, the extraction of U(VI), Ce(IV), Pu(IV), Am(III), and lanthanides(III) by RTILs alone, the extraction of U(VI), Ce(IV), actinides(III,IV), and lanthanides(III) by solvating O-donors, the extraction of Eu(III) by a solvating N-donor, the extraction of lanthanides(III) and Am(III) by acidic extractants, and the extraction of actinides(III,IV) and lanthanides(III) by task specific ionic liquids.