Selective extraction of lithium over alkali and alkaline earth ions by synergistic solvent extraction.

Direct lithium extraction (DLE) from natural surface and geothermal brines is very challenging due to the low ratio of lithium to other metals, and the lack of suitable materials that bind lithium with sufficiently high selectivity. In this paper, a synergistic solvent extraction system is described that comprises a liquid ion exchanger (saponified bis(2-ethylhexyl)dithiophosphoric acid) and a lithium-selective ligand (2,9-dibutyl-1,10-phenanthroline) in an aliphatic diluent. The extraction mechanism was investigated and was confirmed to involve the binding of lithium to the selective ligand, while the liquid ion exchanger facilitates the transfer of metal ions from the aqueous to the organic phase.

Extraction of gallium from simulated Bayer process liquor by Kelex 100 dissolved in ionic liquids.

Two 1,2,3-triazolium ionic liquid diluents were evaluated for the extraction of gallium from spent Bayer process liquor by Kelex® 100. The first of these is a hydrophobic ionic liquid with a low water content, which allows the extraction of gallium directly from untreated Bayer process liquor. The second is based on a hydrophilic ionic liquid and which forms an aqueous biphasic system with concentrated salt solutions.

Enhancing Metal Separations by Liquid-Liquid Extraction Using Polar Solvents.

The less polar phase of liquid-liquid extraction systems has been studied extensively for improving metal separations; however, the role of the more polar phase has been overlooked for far too long. Herein, we investigate the extraction of metals from a variety of polar solvents and demonstrate that, the influence of polar solvents on metal extraction is so significant that extraction of many metals can be largely tuned, and the metal separations can be significantly enhanced by selecting suitable polar solvents. Furthermore, a mechanism on how the polar solvents affect metal extraction is proposed based on comprehensive characterizations.

Selective alkaline stripping of metal ions after solvent extraction by base-stable 1,2,3-triazolium ionic liquids.

Novel 1,2,3-triazolium ionic liquids with a high base stability were synthesized for use in solvent extraction of first-row transition elements and rare earths from chloride media. The synthesis of these ionic liquids makes use of a recently reported, metal-free multicomponent reaction that allows full substitution of the 1,2,3-triazolium skeleton. The physical and chemical properties of these ionic liquids are compared with those of a trisubstituted analog.

New metal extractants and super-acidic ionic liquids derived from sulfamic acid.

Sulfamic acid (NH3-SO3) is an acidic zwitterion with many applications. N-Alkylated derivatives are introduced, which can be used as a new class of metal extractants R2NH-SO3 and as new super-acidic ionic liquids [R2NH-SO3H][Tf2N]. The synthesis, properties and novel applications of this versatile platform are discussed.

Sulfonic acid functionalized ionic liquids for dissolution of metal oxides and solvent extraction of metal ions.

New sulfonic acid functionalized ionic liquids (SAFILs) with bis(trifluoromethylsulfonyl)imide anions were synthesized. These ionic liquids are strong Brønsted acids and can solubilize metal oxides. Water-immiscible SAFILs were used as organic phases in solvent extraction studies.