The separation of gallium from iron by solvent extraction from chloride media is challenging because the anionic chloridometalates, FeCl4- and GaCl4-, display similar chemical properties. However, we report here that the selective separation of gallium from iron in HCl solution can be achieved using the dual-purpose ionic liquid methyltrioctylammonium iodide in a solvent extraction process. In this case, the reduction of Fe3+ to Fe2+ by the iodide counterion was found to inhibit Fe transport, facilitating quantitative Ga extraction by the ionic liquid with minimal Fe extraction from 2 M HCl.
Keywords: NMR spectroscopy; UV-Vis spectrophotometry; ionic liquid; recycling; secondary resources; solvent extraction; sustainability.