Hollow Core-Shell Bismuth Based Al-Doped Silica Materials for Powerful Co-Sequestration of Radioactive I<sub>2</sub> and CH<sub>3</sub>I

Abstract

Developing pure inorganic materials capable of efficiently co-removing radioactive I-2 and CH3I has always been a major challenge. Bismuth-based materials (BBMs) have garnered considerable attention due to their impressive I-2 sorption capacity at high-temperature and cost-effectiveness. However, solely relying on bismuth components falls short in effectively removing CH3I and has not been systematically studied. Herein, a series of hollow mesoporous core-shell bifunctional materials with adjustable shell thickness and Si/Al ratio by using silica-coated Bi2O3 as a hard template and through simple alkaline-etching and CTAB-assisted surface coassembly methods (Bi@Al/SiO2) is successfully synthesized. By meticulously controlling the thickness of the shell layer and precisely tuning of the Si/Al ratio composition, the synthesis of BBMs capable of co-removing radioactive I-2 and CH3I for the first time, demonstrating remarkable sorption capacities of 533.1 and 421.5 mg g(-1), respectively is achieved. Both experimental and theoretical calculations indicate that the incorporation of acid sites within the shell layer is a key factor in achieving effective CH3I sorption. This innovative structural design of sorbent enables exceptional co-removal capabilities for both I-2 and CH3I. Furthermore, the core-shell structure enhances the retention of captured iodine within the sorbents, which may further prevent potential leakage.