In-situ growth nanoscale zero-valent bismuth 3D honeycomb-like material for highly efficient selective capture of iodine vapor in complex environments

During the spent fuel reprocessing, large quantities of radioactive iodine vapor are generated. The complex conditions of high temperature, strong acidity, and high humidity are critical factors to consider when designing iodine vapor adsorbents. This paper reports on the synthesis of an in-situ grown nanoscale zero-valent bismuth-doped polyvinylpyrrolidone (PVP) 3D honeycomb-like porous carbon material (Bi0@PVP-C) for the efficient capture and immobilization of iodine vapor under high temperature, strong acidic, and high humidity conditions. Bi0@PVP-C exhibits a 3D porous honeycomb morphology with abundant layered structures. At 200 °C, its iodine vapor capture capacity reaches an astonishing 1252.16 mg/g, significantly higher than other bismuth-containing adsorbents. Characterization techniques such as XRD, HRTEM, XPS, and density functional theory calculations using the Dmol3 module in Materials Studio software, demonstrate that the primary mechanism involves a chemical reaction between abundant nanoscale zero-valent bismuth particles within the pores of Bi0@PVP-C and iodine vapor. The unique affinity of elemental bismuth for iodine enables the material to selectively capture iodine vapor, forming stable BiI3. Furthermore, due to the excellent acid resistance and hydrophobicity of Bi0@PVP-C, the iodine vapor capture capacities under conditions of pH = 2 and 75 % humidity remain high at 1003.56 mg/g and 1135.27 mg/g, respectively. Compared to the optimal capture capacity, there is only a slight decrease of 19.8 % and 9.3 %. Therefore, Bi0@PVP-C exhibits excellent application potential for iodine vapor capture under complex conditions of high-temperature, high-humidity, and strong acidity.