Research on ultra-efficient removal of thorium ions by Fe3O4/Al-MOF composite material

Thorium ions, known for their elevated toxicity and radioactivity, pose substantial ecological hazards, highlighting the need for efficient technologies to selectively eliminate them from water. The solid adsorption approach has gained widespread use in removing thorium ions because of its notable effectiveness, convenience, and straightforward operation. The key to this method’s success is the solid-phase adsorbent, underscoring the pressing need to develop exceptionally efficient adsorbents for thorium ion removal. Here, we present a novel in situ synthesis approach for enhancing an aluminum-based Metal-Organic Framework (Al-MOF) through the incorporation of iron oxide (Fe 3 O 4 ). The resulting Fe 3 O 4 /Al-MOF composite adsorbent demonstrates exceptional performance: (a) unparalleled adsorption capacity, achieving a remarkable Th(IV) uptake of 3058.0 mg g −1 , significantly outperforming the unmodified Al-MOF (1324.6 mg g −1 ); (b) outstanding selectivity, exhibiting high specificity for Th(IV) adsorption (SF Th/metals  > 1000); (c) superb reusability, with excellent regeneration capabilities (85 % retention after 6 cycles). Through combined FT-IR and XPS analyses, we confirm that carboxylate oxygen atoms and Fe-O adsorption sites are key contributors to the Th(IV) adsorption mechanism. This work advances the design of efficient MOF-based composite adsorbents through valuable insights.