Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Capture of Iodine from Nuclear-Fuel-Reprocessing Off-Gas: Influence of Aging on a Reduced Silver Mordenite Adsorbent after Exposure to NO/NO2

Journal Article · · ACS Applied Materials and Interfaces

Iodine radioisotopes released during nuclear fuel reprocessing must be removed from the off-gas stream before discharge. One promising material for iodine capture is reduced silver mordenite (Ag0Z). Nevertheless, the adsorbent’s capacity will degrade, or age, over time when the material is exposed to other off-gas constituents. Though the overall impact of aging is known, the underlying physical and chemical processes are not. To examine these processes, Ag0Z samples were prepared and aged in 2% NO2 in dry air and in 1% NO in N2 gas streams at 150 °C for up to six months. Aged samples were then characterized using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and X-ray absorption spectroscopy. These techniques show that aging involves two overarching processes: (i) oxidation of the silver nanoparticles present in Ag0Z and (ii) migration of oxidized silver into the mordenite’s inner network. Silver on the nanoparticle’s surface is oxidized through adsorption of O2, NO, and NO2. Additionally, Raman spectroscopy and X-ray absorption spectroscopy indicate that nitrates are the primary products of this adsorption. Most of these nitrates migrate into the interior of the mordenite and exchange at framework binding sites, returning silver to its unreduced state (AgZ). The remaining nitrates exist at a persistent concentration without aggregating into bulk-phase AgNO3. X-ray absorption spectroscopy results further indicate that iodine adsorption occurs on not just Ag0Z but also on AgZ and a portion of the nitrates in the system. AgZ adsorbs a sizable quantity of iodine early in the aging process, but its capacity drops rapidly over time. For well-aged samples, nitrates are responsible for up to 95% of mordenite’s iodine capacity. Overall, these results have enhanced our understanding of the aging process in silver mordenite and are expected to guide the development of superior adsorbents for the capture of radioactive iodine from reprocessing off-gas.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1684654
Alternate ID(s):
OSTI ID: 1768925
OSTI ID: 1770417
Journal Information:
ACS Applied Materials and Interfaces, Journal Name: ACS Applied Materials and Interfaces Journal Issue: 44 Vol. 12; ISSN 1944-8244
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English

References (40)

Nitric Acid, Nitrous Acid, and Nitrogen Oxides book June 2000
Adsorption of iodine on hydrogen-reduced silver-exchanged mordenite: Experiments and modeling journal August 2016
Investigations of the State of Fe in H–ZSM-5 journal September 1999
Infrared and M�ssbauer spectroscopic studies of the interaction of nitric oxide with Fe$z.sbnd;Y zeolite journal July 1982
Chemisorption and surface reactivity of nitric oxide on clean and sodium-dosed Ag(110) journal December 1976
Adsorption, coadsorption, and reactivity of sodium and nitric oxide on Ag(111) journal February 1978
Adsorption of oxygen on Ag(110) studied by high resolution ELS and TPD journal March 1981
Atomic and molecular oxygen adsorption on Ag(111) journal July 1985
The adsorption of nitrogen dioxide on the Ag(110) surface and formation of a surface nitrate journal January 1987
Generation of atomic oxygen on Ag(111) and Ag(110) using NO2: a TPD, LEED, HREELS, XPS and NRA study journal November 1995
Effect of oxygen on NO adsorption on the Ag() surface: evidence for a NO3,ads species journal December 2000
Coadsorption of carbon monoxide and nitric oxide at Ag(111): evidence for a CO–NO surface complex journal May 1998
Coadsorption of nitric oxide and oxygen on the Ag(110) surface journal April 1999
Location of Brønsted sites in mordenite journal November 1997
IR study of CO and NOx sorption on Ag-ZSM-5 journal October 1998
Location of Brønsted sites in D-mordenites by neutron powder diffraction journal April 2000
Adsorption of volatile organic and iodine compounds over silver-exchanged mordenites: A comparative periodic DFT study for several silver loadings journal August 2019
Adsorbents and adsorption models for capture of Kr and Xe gas mixtures in fixed-bed columns journal November 2019
Materials and processes for the effective capture and immobilization of radioiodine: A review journal March 2016
Silver-mordenite for radiologic gas capture from complex streams: Dual catalytic CH3I decomposition and I confinement journal December 2014
MOOSE: A parallel computational framework for coupled systems of nonlinear equations journal October 2009
X-ray Absorption Spectroscopy Investigation of Iodine Capture by Silver-Exchanged Mordenite journal April 2017
A Combined DRIFTS and DR-UV–Vis Spectroscopic In Situ Study on the Trapping of CH 3 I by Silver-Exchanged Faujasite Zeolite journal August 2016
Control of Morphology in Polymer Blends through Light Self-Trapping: An in Situ Study of Structure Evolution, Reaction Kinetics, and Phase Separation journal April 2017
Evaluation of Silver Zeolites Sorbents Toward Their Ability to Promote Stable CH 3 I Storage as AgI Precipitates journal July 2017
From Isolated Ag + Ions to Aggregated Ag 0 Nanoclusters in Silver-Exchanged Engelhard Titanosilicate (ETS-10) Molecular Sieve: Reversible Behavior journal April 2009
Gas phase reaction of nitric oxide with nitric acid journal April 1979
Selective Recovery of Dynamic Guest Structure in a Nanoporous Prussian Blue through in Situ X-ray Diffraction:  A Differential Pair Distribution Function Analysis journal August 2005
Radioactive Iodine Capture in Silver-Containing Mordenites through Nanoscale Silver Iodide Formation journal July 2010
Coordination Chemistry of Fe 2+ Ions in Fe,H-ZSM-5 Zeolite as Revealed by the IR Spectra of Adsorbed CO and NO journal December 2009
Determining Quantitative Kinetics and the Structural Mechanism for Particle Growth in Porous Templates journal October 2011
Interaction of Silver with a NO/O 2 Mixture:  A Combined X-ray Photoelectron Spectroscopy and Scanning Electron Microscopy Study journal June 1998
Impact of the Si/Al ratio on the selective capture of iodine compounds in silver-mordenite: a periodic DFT study journal January 2016
Dissociative iodomethane adsorption on Ag-MOR and the formation of AgI clusters: an ab initio molecular dynamics study journal January 2017
Porous sorbents for the capture of radioactive iodine compounds: a review journal January 2018
The New MRCAT (Sector 10) Bending Magnet Beamline at the Advanced Photon Source
  • Kropf, A. J.; Katsoudas, J.; Chattopadhyay, S.
  • SRI 2009, 10TH INTERNATIONAL CONFERENCE ON RADIATION INSTRUMENTATION, AIP Conference Proceedings https://doi.org/10.1063/1.3463194
conference January 2010
Oxygen adsorption on Ag(111): X-ray photoelectron spectroscopy (XPS), angular dependent x-ray photoelectron spectroscopy (ADXPS) and temperature-programmed desorption (TPD) studies journal August 1999
ATHENA , ARTEMIS , HEPHAESTUS : data analysis for X-ray absorption spectroscopy using IFEFFIT journal June 2005
Iodine Loading of NO Aged Silver Exchanged Mordenite report September 2014
Methods of Gas Phase Capture of Iodine from Fuel Reprocessing Off-Gas: A Literature Survey report February 2007

Similar Records

Adsorption Equilibrium and Modeling of Water Vapor on Reduced and Unreduced Silver-Exchanged Mordenite
Journal Article · Mon Jun 26 00:00:00 EDT 2017 · Industrial and Engineering Chemistry Research · OSTI ID:1399935

Adsorption of iodine on hydrogen-reduced silver-exchanged mordenite: Experiments and modeling
Journal Article · Wed Aug 03 00:00:00 EDT 2016 · AIChE Journal · OSTI ID:1324201

Complete NO and NO2 Aging Study for AgZ (Milestone Report)
Technical Report · Tue Mar 31 00:00:00 EDT 2015 · OSTI ID:1210142