Facile synthesis of defective Cu/MOF-808 with high Cu utilization for efficient iodide adsorption and mechanistic insights

The rapid expansion of nuclear medicine has led to the accumulation of large volumes of iodine-containing radioactive wastewater, posing significant threats to both aquatic ecosystems and human health. To address this issue, an environmentally benign and structurally robust adsorbent, Cu-loaded MOF-808, was synthesized via a simple one-pot method. In static batch adsorption experiments, 0.2Cu/MOF-808(1.0) exhibited a maximum iodide adsorption capacity of 188.7 mg g −1 , with an improved Cu utilization efficiency of 51.5 %. Notably, the material maintained a considerable adsorption capacity of 38.3 mg g −1 even under strongly alkaline conditions (pH = 11.0). Moreover, it displayed excellent selectivity toward iodide in the presence of competing anions such as NO 3 − and SO 4 2− . Comprehensive spectroscopic characterization, including extended X-ray absorption fine structure (EXAFS) analysis, revealed a redox-mediated adsorption mechanism. Specifically, Cu 0 is oxidized to Cu + through interactions with carboxyl groups, followed by electrostatic attraction between Cu + and I − to form CuI, while additional bonding occurs between I − and Zr-O-Zr units to generate Zr-O-I linkages. Overall, this study demonstrates the successful preparation of 0.2Cu/MOF-808(1.0) and underscores its strong potential for efficient iodide removal from radioactive wastewater in nuclear medicine applications.