Embedding silver-based MOFs into amino-functionalized sodium alginate aerogels: Enabling the efficient adsorption and sequestration of radioactive iodine

Effective capture and sequestration of radioactive iodine from nuclear waste are crucial for environmental protection and human health. However, most existing iodine adsorbents are powder-based, which are unfavorable for post-reaction treatment and thus limit their widespread applicability. In this study, a silver-based metal-organic framework (Ag-MOF) was incorporated into amino-functionalized sodium alginate aerogel (SA-PEI) to form a novel moldable, size-tunable, and porous composite aerogel (Ag-MOF/SA-PEI). This integration introduces multiple iodine adsorption sites, including amino groups, carboxyl groups, imidazole nitrogen, and silver-oxo moieties. The synergistic interactions among these sites significantly enhance the binding affinity between the adsorbent and iodine species. Experimental results demonstrate that the Ag-MOF/SA-PEI aerogel can be applied for the capture and sequestration of radioactive iodine in both gaseous and liquid phases, with a saturated adsorption capacity of 6820 mg/g for gaseous iodine and 2400 mg/g for aqueous iodine. These capacities are substantially higher than those of pristine powdered Ag-MOF and SA-PEI with fewer adsorption sites. Notably, the composite exhibits excellent stability after gaseous iodine adsorption, with negligible iodine loss observed during a continuous 9-day monitoring period. Comprehensive structural characterizations and theoretical calculations have elucidated the underlying mechanism of iodine adsorption by Ag-MOF/SA-PEI. Therefore, this study presents a novel design of MOF-based composite aerogel adsorbents and demonstrates an effective approach for the capture and sequestration of iodine in multiphase environments, holding promising potential for practical applications.