Structure and Thermochemistry of Perrhenate Sodalite and Mixed Guest Perrhenate/Pertechnetate Sodalite
- Environmental Sciences Division, Oak Ridge National Laboratory, P.O. Box 2008, MS: 6038, Oak Ridge, Tennessee 37831, United States
- Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, California 95616, United States
- Analytical Development Center, Savannah River National Laboratory, Aiken, South Carolina 29808, United States
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
- Department of Civil &, Environmental Engineering, Princeton University, Princeton, New Jersey 08544, United States
- Department of Materials Science &, Engineering, University of Tennessee, Knoxville, Tennessee 37996, United States
- Chemical &, Engineering Materials Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States
- Chemistry &, Biochemistry, Brigham Young University, Provo, Utah 84602, United States
- Environmental Technology Center, Savannah River National Laboratory, Aiken, South Carolina 29808, United States
Treatment and immobilization of technetium-99 (99Tc) contained in reprocessed nuclear waste and present in contaminated subsurface systems represents a major environmental challenge. One potential approach to managing this highly mobile and long-lived radionuclide is immobilization into micro- and meso-porous crystalline solids, specifically sodalite. We synthesized and characterized the structure of perrhenate sodalite, Na8[AlSiO4]6(ReO4)2, and the structure of a mixed guest perrhenate/pertechnetate sodalite, Na8[AlSiO4]6(ReO4)2-x(TcO4)x. Perrhenate was used as a chemical analogue for pertechnetate. Bulk analyses of each solid confirm a cubic sodalite-type structure (P$$\overline{43}$$n, No. 218 space group) with rhenium and technetium in the 7+ oxidation state. High-resolution nanometer scale characterization measurements provide first-of-a-kind evidence that the ReO4– anions are distributed in a periodic array in the sample, nanoscale clustering is not observed, and the ReO4– anion occupies the center of the sodalite β-cage in Na8[AlSiO4]6(ReO4)2. We also demonstrate, for the first time, that the TcO4– anion can be incorporated into the sodalite structure. Lastly, thermochemistry measurements for the perrhenate sodalite were used to estimate the thermochemistry of pertechnetate sodalite based on a relationship between ionic potential and the enthalpy and Gibbs free energy of formation for previously measured oxyanion-bearing feldspathoid phases. The results collected in this study suggest that micro- and mesoporous crystalline solids maybe viable candidates for the treatment and immobilization of 99Tc present in reprocessed nuclear waste streams and contaminated subsurface environments.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Environmental Management (EM)
- DOE Contract Number:
- SC0012704
- OSTI ID:
- 1409615
- Report Number(s):
- BNL--114667-2017-JA
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 2 Vol. 51; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)
- Country of Publication:
- United States
- Language:
- English
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