Superoxide Radicals in Uranyl Peroxide Solids: Lasting Signatures Identified by Electron Paramagnetic Resonance
Sarah K Scherrer1, Cassandra Gates2, Harindu Rajapaksha1
1Department of Chemistry, University of Iowa, Chemistry Building W374, Iowa City, IA 52242, United States.
Angewandte Chemie (International Ed. in English)
|March 26, 2024
Summary
Reactive oxygen species, like superoxide, are present in uranium peroxide phases such as studtite. Their concentration correlates with the uranium
Area of Science:
- Nuclear Chemistry
- Materials Science
- Radiochemistry
Background:
- Uranium(VI) peroxide phases, including studtite and meta-studtite, are prevalent in nuclear fuel cycles.
- These phases can form as corrosion products under high radiation conditions.
- Reactive oxygen species (ROS) are produced during alpha radiolysis of water.
Purpose of the Study:
- To validate the incorporation and stability of ROS within studtite.
- To identify free radicals in U(VI) peroxide samples using electron paramagnetic resonance (EPR) spectroscopy.
- To investigate the relationship between ROS presence and sample characteristics.
Main Methods:
- Electron paramagnetic resonance (EPR) spectroscopy was employed to detect free radicals.
- Density functional theory (DFT) calculations were performed to interpret EPR signals.
- Analysis included uranium peroxide samples with varying isotopic compositions and ages.
Main Results:
- EPR spectroscopy confirmed the presence of free radicals in U(VI) peroxide samples.
- DFT calculations indicated that a superoxide (O2⁻⋅) species is incorporated into the studtite structure.
- A correlation was found between the radical signal intensity and the product of specific activity multiplied by sample age.
Conclusions:
- The study confirms the incorporation of superoxide radicals within the studtite structure.
- The findings validate the presence and potential stability of ROS in U(VI) peroxide materials.
- The observed correlation suggests that radiolysis contributes to ROS formation and accumulation over time.
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