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Title: Silver-Mordenite for Radiologic Gas Capture from Complex Streams: Dual Catalytic CH3I Decomposition and I Confinement

The effective capture and storage of radiological iodine (129I) remains a strong concern for safe nuclear waste storage and safe nuclear energy. Silver-containing mordenite (MOR) is a longstanding benchmark for iodine capture. In nuclear fuel reprocessing scenarios, complex gas streams will be present and the need for high selectivity of all iodine containing compounds is of the utmost importance for safety and the environment. In particular, a molecular level understanding of the sorption of organic iodine compounds is not well understood. Here we probe the structure and distribution of methyl iodide sorbed by silver-containing MOR using a combination of crystallographic and materials characterization techniques including: infrared spectroscopy, thermogravimetric analysis with mass spectrometry, Micro-X-ray Fluorescence, powder X-ray diffraction analysis, and pair distribution function analysis. The iodine is captured inside the MOR pore in the form of AgI nanoparticles, that is consistent with the pores sizes of the MOR, indicating that the molecule is both physically and chemically captured in the Ag-MOR. The organic component is surface catalyzed by the zeolite via the formation of Surface Methoxy Species (SMS) that result in downstream organics of dimethyl ether and methanol formation.
Authors:
; ; ;
Publication Date:
OSTI Identifier:
1162208
Report Number(s):
INL/JOU-14-31276
Journal ID: ISSN 1387-1811
DOE Contract Number:
DE-AC07-05ID14517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Microporous and Mesoporous Materials; Journal Volume: 200
Research Org:
Idaho National Laboratory (INL)
Sponsoring Org:
DOE - NE
Country of Publication:
United States
Language:
English
Subject:
12 MGMT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES Ag°-Mordenite zeolite; CH3I adsorption and waste form