Bismuth-embedded SBA-15 mesoporous silica for radioactive iodine capture and stable storage

Abstract Efficient capture and stable storage of the long-lived iodine-129 ( 129 I), released as off-gas from nuclear fuel reprocessing, have been of significant concern in the waste management field. In this study, bismuth-embedded SBA-15 mesoporous silica was firstly applied for iodine capture and storage. SBA-15 was functionalized with thiol (-SH) groups, followed by bismuth adsorption with Bi–S bonding, which was thermally treated to form Bi 2 S 3 within SBA-15. The bismuth-embedded SBA-15s demonstrated high iodine loading capacities (up to 540 mg-I/g-sorbent), which benefitted from high surface area and porosity of SBA-15 as well as the formation of thermodynamically stable BiI 3 compound. Iodine physisorption was effectively suppressed due to the large pores present in SBA-15, resulting in chemisorption as a main mechanism for iodine confinement. Furthermore, a chemically durable iodine-bearing material was made with a facile post-sorption process, during which the iodine-incorporated phase was changed from BiI 3 to chemically durable Bi 5 O 7 I. Thus, our results showed that both efficient capture and stabilization of 129 I would be possible with the bismuth-embedded SBA-15, in contrast to other sorbents mainly focused on iodine capture.