Application of Ionic Liquids for the Separation of Rare Earth Metals

Abstract

Liquid-liquid extraction is one of the most important techniques for the separation of rare earth metals in hydrometallurgy. Recently, ionic liquids (ILs) have attracted much attention as green alternatives to conventional organic solvents. Due to the additional advantage of good radiation stability, their application to the separation of fission products in nuclear fuel reprocessing has been promoted. In this article, we summarize the IL-based extraction of rare earth metals and advanced techniques are described.

Highly Selective Synergism for the Extraction of Lanthanoid(III) Ions with β-Diketones and Trioctylphosphine Oxide in an Ionic Liquid

“…[7][8][9] Because ILs can also act as liquid ion exchangers, not only neutral but also charged complexes are extractable into the IL phase by ion exchange with the cationic or anionic constituent of the ILs. [10][11][12][13] Thus, the extractability and separability of metal ions in the IL extraction system are expected to differ from those of the usual organic solvent systems.…”

Surfactant Gel Extraction of Metal Ammine Complexes using SDS and KCl at Room Temperature, and a Small-angle X-ray Diffraction Study of the Surfactant Phase

“…The MDS formed a water-insoluble gel and was deposited from the aqueous solutions below the -48 - 2 ; however, the melting temperatures of these zinc ion pairs are unknown. The horizontal axis in Figure 5 is the Krafft temperature of RSO 3 Na [27], which parallels the melting temperature of the gels of the zinc ion pairs.…”

“…Despite their advantages, extraction methods have a number of shortcomings, the greatest of which is the need for organic solvents, which tend to be flammable and/or toxic substances. The problem of making extraction safer can be solved by finding less toxic extracting agents and interest has been shown in the separation of metal ions via extraction methods using ionic liquids [2] and surfactants [3,4] as the extraction medium.…”

Extraction and Separation of Pt and Pd by an Imidazolium-Based Ionic Liquid Combined with Phosphonium Chloride

“…Since a marked improvement in the extraction ability of metal ions using ILs as a diluent in liquid-liquid extraction was reported in 1999, researchers have focused on the application of ILs to improve solvent extraction methods [11]. Commercial extractants such as crown ethers and octyl(phenyl)-N,N-diisobutylcarbamoylmethyl phosphine oxide (CMPO) and newly synthesized extractants have been used to extract cationic metal ions [10,12]. Furthermore, ILs have been used for extraction both dissolved in organic solvents [13][14][15] and as an undiluted extraction phase [16][17][18][19][20][21][22].…”