Porous Copper-Loaded Zeolites for High-Efficiency Capture of Iodine from Spent Fuel Reprocessing Off-Gas

Capturing volatile radionuclide iodine produced in the nuclear industry is a crucial environmental issue. In previous studies, the principal efficient adsorbent for iodine capture was silver-containing zeolite. As silver-containing zeolites are expensive, alternate copper-loaded porous zeolites, including CuCl loaded NaY reduced by H₂ (denoted as H₂CuY) and CO (denoted as COCuY), were studied for iodine adsorption at moderate temperatures. The current work also discusses the influence of copper valency on iodine adsorption. Due to the copper sites and nanosized pore structure, H₂CuY and COCuY showed high iodine adsorption capacities of 450 and 219 mg/g, respectively. The iodine adsorption capacity of H₂CuY was higher than that of silver-loaded zeolites. Moreover, H₂CuY and COCuY adsorbed volatile iodine through a chemical mechanism involving the copper sites of different valencies, and the Cu⁰ was more effective in adsorbing iodine than Cu⁺. These copper-loaded zeolites with strong chemical interactions with iodine and high iodine adsorption capacities provided the possibility for iodine adsorption application in the nuclear industry.