Ab initio molecular dynamics investigation of the co-adsorption of iodine species with CO and H2O in silver-exchanged chabazite

Abstract

In the field of nuclear energy, there is particular interest for the trapping of harmful iodine species (I₂ and CH₃I) that could be released during a nuclear accident, due to their dangereous impact on the human metabolic processes and the environment. Here, the adsorption of these iodine molecules versus several inhibitory compounds (CO, H₂O, CH₃Cl and Cl₂) in the silver exchanged chabazite zeolite is studied in detail using ab initio molecular dynamics simulations at a realistic temperature and composition. Interestingly, we found that the iodine molecules remain attached to the cations even when the number of water molecules inside the structure is greater than two times the number of cations per cell at T = 413 K. For CO, we found that CH₃I is more perturbed than I₂ by the presence of this inhibitor. Overall, our results indicate that the silver-exchanged chabazite zeolite is a promising candidate to trap iodine species in the case of a severe nuclear accident.