Abstract
The separation of hexavalent americium from the lanthanides in simulated PUREX raffinate solution using 1 M diamylamylphosphonate in dodecane extraction was investigated. Hexavalent americium was prepared using room-temperature sodium bismuthate oxidation. Under these conditions the majority of the lanthanides were not oxidized and remained inextractable. A separation factor of ~50 was provided for americium from europium over the nitric acid concentration range 6-7 M. Cerium was the exception with oxidation to Ce IV resulting in its co-extraction with Am VI. However, since americium is readily reduced to Am III it was easily stripped with a dilute acidic solution of hydrogen peroxide. Although hydrogen peroxide also reduces cerium, it does so slowly, and a selective americium strip was achieved, with a separation factor of as high as 35. Alternatively, since americium spontaneously reduced in the loaded organic phase, samples allowed to stand for 2 hours could be selectively stripped of americium by contact with 1 M HNO 3 containing no additional reagents. Further, the separation was demonstrated using solutions containing macro-amounts of cerium and americium. The implications for use in fuel cycle separations are discussed.
Original language | English |
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Pages (from-to) | 445-456 |
Number of pages | 12 |
Journal | Solvent Extraction and Ion Exchange |
Volume | 30 |
Issue number | 5 |
DOIs | |
State | Published - Aug 2012 |
Externally published | Yes |
Funding
Work supported by the U.S. Department of Energy, Assistant Secretary for Nuclear Energy, under the Fuel Cycle Research and Development Minor Actinide Separations σ -team; DOE Idaho Operations Office Contract DE-AC07-05ID14517. The authors thank E.P. Horwitz, for initially suggesting the use of DAAP as an AmVI extraction ligand.
Keywords
- Americium
- americium extraction
- americium oxidation
- minor actinides
- phosphonate
- separation
- sodium bismuthate