A Redox-Active Metal-Sulfide Framework for Selective and Synergistic Removal of Iodate

Efficient removal of iodate (IO3-) from radioactive liquid waste is highly desirable for radioactive waste management and environmental protection but remains a formidable challenge due to the low adsorption capacity or insufficient removal depth resulting from the weak affinity of conventional single-function adsorbents. Here, we report a redox-active metal-sulfide framework (SCU-SnS) that enables the highly efficient decontamination of IO3- through a synergistic effect: efficient reduction of IO3- to I- by S2- sites, combined with an extremely high binding affinity between Sn4+ sites and the resulting I-. Benefiting from this synergistic effect of redox and iodination reactions, SCU-SnS features both an exceptionally high distribution coefficient (Kd = 1.58 × 106 mL/g) and a remarkable adsorption capacity of 1022.8 mg/g for IO3- removal. Notably, SCU-SnS demonstrates an unparalleled selectivity, capable of nearly quantitative removal of IO3- in the coexistence of a 100-fold excess of various competing anions, including Cl-, NO3-, CO32-, and SO42-. This synergistic strategy not only delivers a promising adsorbent for IO3- decontamination under highly competitive environments but also inspires an alternative approach to designing advanced adsorbents for nuclear waste management.