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

Area of Science:

• Materials Science
• Environmental Chemistry
• Nuclear Engineering

Background:

• Radioactive iodine poses significant environmental and health risks.
• Efficient management of radionuclides from nuclear processes is crucial.
• Development of effective iodine adsorbents is needed.

Purpose of the Study:

• To synthesize and evaluate a novel silver-thione-functionalized zeolitic imidazole framework (ZIF) for radioactive iodine uptake.
• To compare the iodine adsorption performance of the functionalized ZIF with the parent ZIF-8 and intermediate materials.
• To understand the mechanism behind enhanced iodine capture.

Main Methods:

• Post-synthetic modification of ZIF-8 using solvent-assisted ligand exchange.
• Functionalization with 2-mercaptoimidazole to form ZIF-8 = S.
• Reaction with silver nitrate to create the Ag-functionalized composite (ZIF-8 = S-Ag+).
• Assessment of iodine (I2) adsorption capacity and kinetics.

Main Results:

• The Ag-functionalized ZIF (ZIF-8 = S-Ag+) exhibited superior I2 adsorption capacity (550 g I2/mol) compared to pristine ZIF-8 (450 g I2/mol).
• The functionalized material demonstrated significantly faster adsorption kinetics, reaching 50% loading in 5 hours and saturation in 50 hours.
• Despite having a lower BET surface area, the Ag-functionalized ZIF showed enhanced performance due to strong Ag-I interactions.

Conclusions:

• Silver-thione functionalization of ZIFs is an effective strategy for enhancing radioactive iodine capture.
• The engineered adsorbent offers a promising solution for managing radioactive iodine in nuclear fuel cycle applications.
• This study advances the understanding of adsorbent design for robust iodine uptake behavior.