Rare earth elements (REEs) are critical raw materials with a wide range of industrial applications. As a result, the recovery of REEs via adsorption from REE-rich matrices, such as water streams from processed electronic waste, has gained increased attention for its simplicity, cost-effectiveness and high efficacy. In this work, the potential of nanometric cerium oxide-based materials as adsorbent for selected REEs is investigated. Ultra -small cerium oxide nanoparticles (CNPs, mean size diameter ≈ 3 nm) were produced via a precipitation-hydrothermal procedure and incorporated into woven non-woven polyvinyl alcohol (PVA) nanofibres (d ≈ 280 nm) via electrospinning, to a final loading of ≈34 wt%. CNPs, CNP-PVA and the benchmark material CeO2 NM-212 (JRCNM02102, mean size diameter ≈ 28 nm) were tested as adsorbents for aqueous solutions of the REEs Eu3+, Gd3+ and Yb3+ at pH 5.8. Equilibrium adsorption data were interpreted by means of Langmuir and Freundlich data models. The maximum adsorption capacities ranged between 16 and 322 mgREE gCeO2-1, with the larger value found for the adsorption of Yb3+ by CNP. The trend of maximum adsorption capacity was CNPs > NM-212 > CNP-PVA, which was ascribed to different agglomeration and surface area available for adsorption. Langmuir equilibrium constant KL were substantially larger for CNP-PVA, suggesting a potential higher affinity of REEs for CNPs due to a synergistic effect of PVA on adsorption. CNP-PVA were effectively used in repeated adsorption cycles under static and dynamic configurations, and retained the vast majority of adsorptive material (> 98% of CeO2 retained after 10 adsorption cycles). The minimal loss was attributed to partial solubilisation of fibre components with change in membrane morphology.

JRC.F.2 - Consumer Products Safety