TY - JOUR
T1 - X-ray Absorption Spectroscopy Investigation of Iodine Capture by Silver-Exchanged Mordenite
AU - Abney, Carter W.
AU - Nan, Yue
AU - Tavlarides, Lawrence L.
N1 - Funding Information:
This invited contribution is part of the I&EC Research special issue for the 2017 Class of Influential Researchers. This research was conducted at Oak Ridge National Laboratory (ORNL) and Syracuse University (SU). Funding for work at ORNL was provided by ORNL's Laboratory Directed Research and Development program. Work at SU was sponsored by the U.S. Department of Energy (DOE), Nuclear Energy University Program (NEUP), Project: 14-6423 and Grant NE0008275. CWA would like to thank Dr. Radu Custelcean for helpful conversations regarding the crystal structure of α-AgI and Dr. Mark Antonio for equally helpful conversations regarding the theory of XAFS and limitations of principal component analysis. XAFS data were collected at the Advanced Photon Source at Argonne National Laboratory on Beamline 10ID-B, supported by the Materials Research Collaborative Access Team (MRCAT). MRCAT operations are supported by the DOE and the MRCAT member institutions. The Advanced Photon Source is a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. The United States Government retains, and by accepting the article for publication the publisher acknowledges that the United States Government retains, a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for the United States Government Purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).
Publisher Copyright:
© 2017 American Chemical Society.
PY - 2017/4/26
Y1 - 2017/4/26
N2 - Capture of radioactive iodine is a significant consideration during reprocessing of spent nuclear fuel and disposal of legacy wastes. While silver-exchanged mordenite (AgZ) is widely regarded as a benchmark material for assessing iodine adsorption performance, previous research efforts have largely focused on bulk material properties rather than the underpinning molecular interactions that achieve effective iodine capture. As a result, the fundamental understanding necessary to identify and mitigate deactivation pathways for the recycle of AgZ is not available. We applied X-ray Absorption Fine Structure (XAFS) spectroscopy to investigate AgZ following activation, adsorption of iodine, regeneration, and recycle, observing no appreciable degradation in performance due to the highly controlled conditions under which the AgZ was maintained. Fits of the extended XAFS (EXAFS) data reveal complete formation of Ag0 nanoparticles upon treatment with H2, and confirm the formation of α-AgI within the mordenite channels in addition to surface γ/β-AgI nanoparticles following iodine exposure. Analysis of the nanoparticle size and fractional composition of α-AgI to γ/β-AgI supports ripening of surface nanoparticles as a function of recycle. This work provides a foundation for future investigation of AgZ deactivation under conditions relevant to spent nuclear fuel reprocessing.
AB - Capture of radioactive iodine is a significant consideration during reprocessing of spent nuclear fuel and disposal of legacy wastes. While silver-exchanged mordenite (AgZ) is widely regarded as a benchmark material for assessing iodine adsorption performance, previous research efforts have largely focused on bulk material properties rather than the underpinning molecular interactions that achieve effective iodine capture. As a result, the fundamental understanding necessary to identify and mitigate deactivation pathways for the recycle of AgZ is not available. We applied X-ray Absorption Fine Structure (XAFS) spectroscopy to investigate AgZ following activation, adsorption of iodine, regeneration, and recycle, observing no appreciable degradation in performance due to the highly controlled conditions under which the AgZ was maintained. Fits of the extended XAFS (EXAFS) data reveal complete formation of Ag0 nanoparticles upon treatment with H2, and confirm the formation of α-AgI within the mordenite channels in addition to surface γ/β-AgI nanoparticles following iodine exposure. Analysis of the nanoparticle size and fractional composition of α-AgI to γ/β-AgI supports ripening of surface nanoparticles as a function of recycle. This work provides a foundation for future investigation of AgZ deactivation under conditions relevant to spent nuclear fuel reprocessing.
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U2 - 10.1021/acs.iecr.7b00233
DO - 10.1021/acs.iecr.7b00233
M3 - Article
AN - SCOPUS:85020191403
SN - 0888-5885
VL - 56
SP - 4837
EP - 4846
JO - Industrial and Engineering Chemistry Research
JF - Industrial and Engineering Chemistry Research
IS - 16
ER -