Tailoring the coordination microenvironment of electrospun nanofibers for the separation of thorium ions from ore wastewater

Abstract

Confronted with the intricate presence of multiple metal ions in thorium mineral wastewater, electrospun nanofibers characterized by high porosity and easy functionalization are anticipated to emerge as distinctive adsorbents for the efficient and selective removal of thorium ions from water. Herein, the coordination microenvironment of electrospun nanofibers was tailored by the hyperbranched grafting and introduction of salicylaldehyde based groups, which displayed high affinity and selectivity toward Th(IV) ions. The obtained electrospun nanofibers showed fast adsorption kinetics of 60 min and high uptake capacity of 781.3 mg g⁻¹, which were superior to most of shapeable adsorbents and comparable to many powder adsorbents. The nanofiber adsorbent also exhibited a high distribution coefficient (K_d) of 3.1 × 10⁵ mL g⁻¹ and good anti-interference ability against rare earth ions and uranyl ion. Based on the experimental characterizations and theoretical calculations, the grafted plenty of hydroxyl and Schiff base groups played the major role in achieving strong and selective Th(IV) ion binding. In addition, the macroscopical membrane morphology could effectively separate Th(IV) ions from water via dynamic filtration with a treatment volume 996 times its own membrane volume. This study not only offers new materials as efficient Th(IV) adsorbents but also provides a potential strategy for the recovery of nuclear fuel from wastewater.