Comprehensive comparison of bismuth and silver functionalized nickel foam composites in capturing radioactive gaseous iodine.

Developing an efficient and cheap iodine sorbent is of great practical significance in the modern nuclear industry. In this work, novel bismuth and silver functionalized Ni foam composites as iodine sorption materials (Bi-Ni foam and Ag-Ni foam) were successfully prepared via a simple solvothermal method. Through a series of iodine sorption experiments and characterization methods, iodine capture properties and corresponding sorption mechanism were comprehensively compared and thoroughly revealed. The results show that the core-sheath structure formed by the solvothermal reaction can supply more active sites (Bi0 or Ag0 particles) for the contact of radioactive iodine gas, thereby improving the sorption capacity of sorbents. Compared with Ag-Ni foam (456 mg/g), Bi-Ni foam exhibits a higher iodine capture capacity (658 mg/g), whereas silver-based material has a faster sorption kinetics. Such excellent sorption performances were attributed to the chemical reaction between Bi0/Ag0 particles and iodine gas, generating stable BiI3/AgI. In addition, this type of sorbents inherits the external structure of the Ni foam skeleton, decreasing the physically sorbed iodine, and can be prepared in different shapes and sizes, which is of great practical significance.