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Plutonium(IV) Sorption during Ferrihydrite Nanoparticle Formation
Kurt F Smith1, Katherine Morris1, Gareth T W Law2,3
1Research Centre for Radwaste Disposal and Williamson Research Centre for Molecular Environmental Science, School of Earth and Environmental Sciences, The University of Manchester, Manchester, M13 9PL, United Kingdom.
ACS Earth & Space Chemistry
|February 18, 2020
Summary
Plutonium strongly binds to iron oxyhydroxide nanoparticles during ferrihydrite precipitation. This suggests long-term retention of plutonium in contaminated environments and waste disposal scenarios.
Area of Science:
- Environmental Science
- Radiochemistry
- Materials Science
Background:
- Understanding iron (oxyhydr)oxide nanoparticle interactions with plutonium is crucial for radioactive waste management and environmental remediation.
- Plutonium sequestration involves adsorption, precipitation, and incorporation processes.
Purpose of the Study:
- To investigate the mechanisms of plutonium sequestration during ferrihydrite precipitation.
- To analyze the structural complexation of plutonium on ferrihydrite surfaces.
Main Methods:
- Controlled hydrolysis of acidic solutions containing Fe(III) and Pu(IV) to induce ferrihydrite precipitation.
- Extended X-ray absorption fine structure (EXAFS) spectroscopy to analyze plutonium speciation and surface complexation.
Main Results:
- Plutonium sequestration occurred concurrently with ferrihydrite formation between pH 2 and 3.
- EXAFS analysis revealed Pu(IV) forms an inner-sphere tetradentate complex on the ferrihydrite surface.
- The Pu(IV)-Fe oxyhydroxide complex remained stable despite ferrihydrite recrystallization to hematite over 6 months.
Conclusions:
- Plutonium is strongly sorbed to iron oxyhydroxide surfaces, indicating potential for long-term retention.
- These findings support the use of iron-based materials for treating radioactive waste and contaminated sites.
