Advancing towards technology readiness: Continuous-flow electrosorption for thorium separation from rare earth processing by-products

This study focuses on the development of a curated separation system aimed at separating thorium ions as part of a recovery plan for managing the thorium radionuclide in the rare earth element (REE) processing industry. As a step towards advancing technology readiness, the separation system employs the electrosorption technique, which involves the migration and storage of thorium ions in the electrical double layers on the porous surface of a carbon-based electrode. Using a prototype electrosorption cell operated at an applied voltage of 1.0 V, the system successfully achieved a thorium ion recovery rate of 84.5 ± 0.29 %, with an impressive electrosorption capacity of 105.26 mg-Th/1 g-carbon. Notably, despite the presence of higher concentrations of REE as competing ions, greater selectivity towards thorium was observed which likely attributable to its larger ionic radius, higher electron affinity, and greater distribution coefficient. These findings highlight the efficacy of the curated separation system and its potential to balance between REE economic significance as well as a protection to the environment.