The influence of ozone on ligand-assisted extraction of Pu-239 and Am-241 from Rocky Flats soil

摘要

Chemical extraction of Pu-239 and Am-241 from a Rocky Flats soil matrix was studied at 50degreesC using four ligands; citric acid and ascorbic acid at pH 2, EDTA and carbonate at pH 10. The soil was treated for a 12-hour reaction period with ozone gas prior to the addition of ligands. With the carbonate ligand, the ozone treatment continued during the entire extraction. High Pu removal was found at pH 2 with ascorbic acid and pH 10 with carbonate. Both maintained redox conditions during the extraction. For the carbonate system, a trend of increased extraction with increasing E-h and carbonate concentration was observed. Ozone treatment of soil prior to addition of EDTA at pH 10 and citric acid at pH 2 was shown to dramatically increase extraction of Am. Since no oxidation of Am occurred, the increased removal from ozone is mainly due to the oxidation of the soil phase containing the Am. [References: 18]