Enhanced Iodine Capture Using a Postsynthetically Modified Thione–Silver Zeolitic Imidazole Framework

Abstract

Efficient management of radionuclides that are released from various processes in the nuclear fuel cycle is of significant importance. Among these nuclides, radioactive iodine (mainly 129I and 131I) is a major concern due to the risk it poses to the environment and to human health; thus, the development of materials that can capture and safely store radioactive iodine is crucial. Herein, a novel silver–thione-functionalized zeolitic imidazole framework (ZIF) was synthesized via postsynthetic modification and assessed for its iodine uptake capabilities alongside the parent ZIF-8 and intermediate materials. A solvent-assisted ligand exchange procedure was used to replace the 2-methylimidazole linkers in ZIF-8 with 2-mercaptoimidazole, forming intermediate compound ZIF-8 = S, which was reacted with AgNO3 to yield the ZIF-8 = S–Ag+ composite for iodine uptake. Despite possessing the lowest BET surface area of the derivatives, the Ag-functionalized material demonstrated superior I2 adsorption in terms of both maximum capacity (550 g I2/mol) and rapid kinetics (50% loading achieved in 5 h, saturation in 50 h) compared to that of our pristine ZIF-8, which reached 450 g I2/mol after 150 h and 50% loading in 25 h. This improvement is attributed to the presence of the Ag+ ions, which provide a strong chemical driving force to form a stable Ag–I species. The results of this study contribute to a broader understanding of the strategies that can be employed to engineer adsorbents with robust iodine uptake behavior.

Silver Nanoparticle-Functionalized Postsynthetically Modified Thiol MOF UiO-66-NH-SH for Efficient CO2 Fixation

“…The successful condensation reaction between the NH 2 groups of UiO-66-NH 2 and the COOH groups of thioglycolic acid is confirmed by the presence of the thiol group at 2555 cm –1 in the FT-IR spectra of UiO-66-NH-SH (1) (Figure S1a). − The observation is further supported by the transformation of the sharp NH 2 bending FT-IR peak (1649 cm –1 ) of UiO-66-NH 2 to a low-intensity broad peak, indicating the formation of an amide bond (Figure S1b). Also, in the case of UiO-66-NH-SH (1), the intensity of the NH–CO peak at 1568 cm –1 increases, while the intensity of the C–N peak at 1255 cm –1 weakened in comparison to UiO-66-NH 2 .…”