Imidazole and Bismuth Co-Modified Silicalite-1 Zeolite for Immobilization of Radioactive Iodine Gaseous Species

The efficient capture of both I2 and CH3I is of critical importance for environmental remediation due to their high toxicity and environmental mobility. In this study, an imidazole and bismuth co-loaded silicalite-1 zeolite (Im@Bi-TSL-1) was synthesized by a combined hydrothermal reduction and solid-phase adsorption method. Based on the dual function strategy, Im@Bi-TSL-1 exhibited a maximum adsorption capacity of 2494.5 mg/g for I2 and 568.6 mg/g for CH3I, with BiI3 and BiOI identified as the final adsorption products resulting from the synergistic methylation reaction and metal-based reaction. Moreover, the Im@Bi-TSL-1 after CH3I adsorption (Im@Bi-TSL-1-CH3I) exhibited a maximum iodide leaching rate of 39.2% in pure water at 72 h, surpassing that of commercial Ag-loaded zeolite (AgZ). The TSL-1-based composite delivered superior performance across multiple evaluation metrics, underscoring its potential for iodine capture. This study provides a design reference for the development of high-performance radioactive iodine adsorbents, aiming to achieve efficient removal and immobilization of iodine gaseous species.