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Functionalized ionic liquids enhance L-L extraction of Ga and Ge

| By Scott Jenkins

Gallium and germanium are considered critical materials due to their multiple uses in semiconductors, optics, healthcare and pharmaceuticals, and other high-technology applications. Current solvent-based extraction methods for recovering these elements suffer from significant drawbacks, such as low separation efficiency, poor selectivity and the generation of large amounts of waste solvents.

Research at the Missouri University of Science and Technology (MST; Rolla, Mo.; www.mst.edu) is aimed at addressing those drawbacks. Lana Alagha, associate professor of mining engineering at MST, and colleagues were recently awarded a grant of $875,000 from Rio Tinto (London, U.K.; www.riotinto.com) for a two-year project to develop technology that uses functionalized ionic liquids (ILs) for extraction of Ga and Ge from aqueous waste products resulting from copper mining.

“Functionalized ILs have task-specific ligands that facilitate the metal extraction by a solvation mechanism, rather than by an ion-exchange mechanism, thus extending the lifetime of the extractant and eliminating the need for a costly saponification process,” explains Alagha in a patent covering the technology. Complexing functionalities are incorporated into both anionic and cationic parts of the ILs, and researchers can change the anion and cation of the IL to tailor the structure and target specific metals, Alagha says.

“The inner synergistic effect provided by both cation and anion helps to improve the loading capacity and kinetics of the extraction process,” allowing enhanced recovery and separation of Ga and Ge, Alagha notes. “There is currently little-to-no production of these two elements in the U.S., and we rely to an alarming extent on importing them.”