Core-shell nanoparticles bearing Schiff base ligand for the selective extraction of uranium from REE leach liquors

Abstract The synthesis of core-shell (Fe3O4@SiO2) magnetic nanoparticles (MNP) functionalized using a Schiff base ligand (bis(3-methoxysalicylaldehyde)-o-phenylenediimine; MeOSalophen) for uranium extraction is reported. Extractive performances with respect to pH, adsorption kinetics, chemical nature of the equilibration phase, and elemental selectivity were evaluated and a maximal adsorption capacity of 92 mg g−1 at pH 6 in presence of sulfate ions for an equilibration time of 4 h was determined. The functionalized MNP offer very high affinity for uranyl ion (Kd > 11,000 mL g−1) as well as a high degree of selectivity for this element over several metal ions present in leach liquors containing rare earth elements . While Th was also extracted with the functionalized MNP, equivalent extractive performances were achieved with the non-functionalized counterpart, suggesting that this element is most likely adsorbed on the surface of the silica coating layer. The Schiff base-functionalized core-shell nanoparticles also exhibited a high degree of reusability in the conditions tested.