Author:

Keywords:

rare earths, lanthanides, magnetic nanoparticles

Abstract:

To address the shortage of certain critical rare earths, researchers are looking at new ways to efficiently retrieve these elements from user products like magnets, energy‐saving light bulbs and batteries.1 Magnetic nanoparticles have shown great potential as re‐usable and green extractants in diluted waste streams because they can be retrieved with a magnet.2,3 These “nanosponges” can adsorb rareearth ions and remove them from solution. Fe3O4, SiO2 and TiO2 nanoparticles were decorated with EDTA‐silane groups that have a large affinity for rare‐earth ions. The adsorption and separation ability of the different nanoparticles was compared and significant differences were observed based on the density of ligands on the various surfaces. Functionalized SiO2 nanoparticles showed the highest adsorption capacity and selectivity, but did not have the advantage of magnetic retrieval. Therefore, the next logical step was to make nanoparticles with a magnetic Fe3O4 core and a SiO2 shell, and functionalize this shell with EDTA‐silane. These coreshell nanoparticles combine the advantage of magnetic retrieval with the increased selectivity of SiO2 nanoparticles.