Pertechnetate/perrhenate–capped Zr/Hf–Dihydroxide Dimers: Elucidating Zr–TcO4 Co–Mobility in the Nuclear Fuel Cycle
Journal Article
·
· Chemistry - A European Journal
- Oregon State University, Corvallis, OR (United States); University of Notre Dame
- Oregon State University, Corvallis, OR (United States)
Spent nuclear fuel contains heavy element fission products that must be separated for effective reprocessing for a safe and sustainable nuclear fuel cycle. 93Zr and 99Tc are high-yield fission products that co-transport in liquid-liquid extraction processes. Here we seek atomic-level information of this co-extraction process, as well as fundamental knowledge about ZrIV (and HfIV) aqueous speciation in the presence of topology-directing ligands such as pertechnetate (TcO4–) and non-radioactive surrogate perrhenate (ReO4–). In this context, we show that the flat tetrameric oxyhydroxyl-cluster [MIV4(OH)8(H2O)16]8+ (and related polymers) is dissociated by perrhenate/pertechnetate to yield isostructural dimers, M2(OH)2(XO4–)6(H2O)6 • 3H2O (M=Zr/HfIV; X=Re/TcVII), elucidated by single-crystal X-ray diffraction. We used these model compounds to understand the pervasive 93Zr-99Tc coextraction with further speciation studies in water, nitric acid, and tetrabutylphosphate (TBP) -kerosene; where the latter two media are relevant to nuclear fuel reprocessing. SAXS (small angle X-ray scattering), compositional evaluation, and where experimentally feasible, ESI-MS (electrospray ionization mass spectrometry) showed that perrhenate/pertechnetate influence Zr/HfIV-speciation in water. Here, in Zr-XO4 solvent extraction studies to simulate fuel reprocessing, we provide evidence that TcO4– enhances extraction of ZrIV, and compositional analysis of the extracted metal-complexes (Zr-ReO4 study) is consistent with the crystallized ZrIV2(OH)2(ReVIIO4–)6(H2O)6•dimer.
- Research Organization:
- University of Notre Dame, IN (United States)
- Sponsoring Organization:
- Murdock Charitable Trust; USDOE; USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- NA0003763
- OSTI ID:
- 2279027
- Alternate ID(s):
- OSTI ID: 2274837
- Journal Information:
- Chemistry - A European Journal, Journal Name: Chemistry - A European Journal Journal Issue: 10 Vol. 30; ISSN 0947-6539
- Publisher:
- WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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