Synthesis of an Ag-based metal-organic framework for effective capture of iodine pollutants

The effective capture of radioiodine exhausted from nuclear power plants, is of paramount importance for the radioactivity control and remediation tasks. Herein, a robust metal-organic framework Ag-Tipe integrating with open Ag+ metal sites and imidazole groups is designed for efficient capture of I-2 and CH3I. The dense imidazolium groups are expected to interact with the I-2 through charge transfer, enhancing the binding affinity and trapping CH3I as a reactant in the methylation reaction. In addition, the fully open silver metal center in Ag-Tipe can coordinate with iodine species to form AgI. Therefore, the Ag-Tipe exhibits high I-2 and CH3I uptake capacities of 3.31 and 0.55 g/g at 75 degrees C, respectively. The density functional theory (DFT) calculations reveal that the I-2 and CH3I binding energy at different sites in Ag-Tipe follows the order Ag > imidazole > benzene ring. This work demonstrates the important role of the binding site of the adsorbent in achieving high I-2/CH3I trapping performance.