Sulfur Vacancy-Rich Bismuth Sulfide Nanowire Derived from CAU-17 for Radioactive Iodine Capture in Complex Environments: Performance and Intrinsic Mechanisms

Effective capture and immobilization of volatile radioiodine from the off-gas of post-treatment plants is crucial for nuclear safety and public health, considering its long half-life, high toxicity, and environmental mobility. Herein, sulfur vacancy-rich Vs-Bi2S3@C nanocomposites were systematically synthesized via a one-step solvothermal vulcanization of CAU-17 precursor. Batch adsorption experiments demonstrated that the as- synthesized materials exhibited superior iodine adsorption capacity (1505.8 mg g(-1) at 200 degrees C), fast equilibrium time (60 min), and high chemisorption ratio (91.7%), which might benefit from the nanowire structure and abundant sulfur vacancies of Bi2S3. Furthermore, Vs-Bi2S3@C composites exhibited excellent iodine capture performance in complex environments (high temperatures, high humidity and radiation exposure). Mechanistic investigations revealed that the I-2 capture by fabricated materials primarily involved the chemical adsorption between Bi2S3 and I-2 to form BiI3, and the interaction of I-2 with electrons provided by sulfur vacancies to form polyiodide anions (I-3(-)). The post-adsorbed iodine samples were successfully immobilized into commercial glass fractions in a stable form (BixOyI), exhibiting a normalized iodine leaching rate of 3.81 x 10(-5) g m(-2) d(-1). Overall, our work offers a novel strategy for the design of adsorbent materials tailed for efficient capture and immobilization of volatile radioiodine.