Highly efficient capture of iodine in spent fuel reprocessing off-gas by novelly porous copper-doped silica zeolites

Spent fuel reprocessing is the main part of the closed recycling of nuclear fuel. The efficient capture of radioactive iodine in spent fuel reprocessing remains a major issue for the safe utilization of nuclear energy. To possibly substitute the silver-containing zeolites of high cost, copper-doped porous silica including microporous silicalite-1 zeolite (denoted as Cu-S-1) and mesoporous SBA-15 (denoted as Cu-SBA-15) different from those of copper-exchanged ones previously reported were investigated for iodine adsorption at moderate temperature. The influence of pore diameter on iodine adsorption was emphatically discussed. Because of the nanosized pore structure, Cu-S-1 and Cu-SBA-15 exhibited high iodine adsorption capacities of 501 mg g −1 and 59 mg g −1 , respectively. The iodine adsorption capacity of Cu-S-1 was higher than those of the silver-containing ones reported up to now. Moreover, it was revealed that the microporous structure was more beneficial to adsorb iodine than the mesoporous structure. These copper-doped silica zeolites provide the possibility for the application of iodine adsorption in practical post-processing conditions.