Nuclear chemistry

Catalysis

Adsorption

Inorganic chemistry

Soil water

Dissolution

Bismuth

Organic chemistry

Mordenite

Iodine

Zeolite

Environmental science

Soil science

Chemistry

Leaching (pedology)

Sorbent

Chemical Engineering Journal

The search for efficient, cheap, and robust sorbent materials which can effectively remove iodine compounds from off-gas streams in used nuclear fuel reprocessing facilities is still challenging. Herein, we report the development of bismuth-doped mordenite zeolite with different loadings for removal of iodine-129 (129I) from nuclear waste off-gas streams. Of the materials investigated, bismuth-mordenite with 5 wt% bismuth content (Bi5@Mordenite) exhibited the highest capture capacity with an iodine uptake capacity up to 538 mg/g after exposure to iodine for 6 h at 200 °C, which was ~2.5 times higher than that of the bare mordenite with relatively fast kinetics. Interestingly, the bismuth-doped mordenite sample exhibited higher surface area and porosity than those of the bare zeolite as a result of mordenite dealumination during bismuth incorporation. Moreover, the leach tests were carried out to determine the degree of iodine leaching from the iodine-loaded Bi5@Mordenite upon coming into contact with DI water and the results revealed a maximum iodine amount of 36% that was released from the adsorbent after 24 h exposure, highlighting the necessity of transforming the iodine-loaded adsorbent into a suitable waste form for permanent geological disposal. Overall, the high uptake capacity and fast uptake rate of iodine reveal the potential utility of bismuth-based zeolites as iodine capture materials when consolidated into a waste form for long-term decay storage.

Development of bismuth-mordenite adsorbents for iodine capture from off-gas streams