## Abstract The enhanced dissolution of uranium oxides by the application of ultrasound in supercritical fluid carbon dioxide containing dissolved 4,4‐trifluoro‐1‐(2‐thienyl)‐1,3‐butanedione and tributyl phosphate is demonstrated. Under conditions of 60 °C and 150 atm the steady state dissolution o
Kinetics of corrosion and dissolution of uranium dioxide as a function of pH
✍ Scribed by M. E. Torrero; E. Baraj; J. de Pablo; J. Giménez; I. Casas
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 120 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
A continuous flow-through reactor with a thin layer of solid particles (size ranging from 100 to 300 m) was used to obtain a deeper knowledge on the mechanism of dissolution of UO 2 under oxidizing conditions. Using this methodology the dissolution rate of uranium dioxide was determined at three different oxygen partial pressures (5, 21, and 100% in nitrogen) and as a function of pH (between 3 and 12) in a noncomplexing medium.
From the results of these experiments the following rate equation was derived:
In addition, XPS characterizations were performed to determine the U(IV)/U(VI) ratio on the solid surface at different experimental times and conditions. These results showed that at acidic conditions (pH below 6.7) the final solid surface presents a stoichiometry close to UO 2 , while at alkaline conditions the final solid surface average composition is close to UO 2.25 . This information was integrated with the results of the leaching experiments to present a model for the mechanism of dissolution of uranium dioxide under the experimental conditions.
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