Chemical Extraction of Plutonium and Americium from Contaminated Rocky Flats Soil
Article
Kung, KS, Lu, N, Triay, IR et al. (1998). Chemical Extraction of Plutonium and Americium from Contaminated Rocky Flats Soil
. RADIOCHIMICA ACTA, 80(1), 13-21.
Kung, KS, Lu, N, Triay, IR et al. (1998). Chemical Extraction of Plutonium and Americium from Contaminated Rocky Flats Soil
. RADIOCHIMICA ACTA, 80(1), 13-21.
Chemical batch extraction and column leaching processes were conducted to evaluate the removal of plutonium and americium from contaminated Rocky Flats soil. Citrate solutions in conjunction with ascorbate or dithionite were used as extractants. Effects of extractant concentration, solid to solution ratio, solution pH, extraction time, and temperature on radionuclide removal were investigated. Results demonstrate that the removal of radioactivities using a citrate-dithionite system is generally higher than that using a citrate-ascorbate system. In the citrate-dithionite system, results show that (1) total radioactivity could be removed with more than 90% efficiency, (2) radionuclide removal is strongly correlated to extractant concentration and the solid-to-solution ratio, and (3) there is no effect of extraction time and initial solution pH on radionuclide removal. In the citrate-ascorbate system, conversely, better correlation between removal efficiency and extraction time is identified, which is possibly attributed to the relatively stable reducing condition in the system. The removal of plutonium is sensitive to extractant concentration, which suggests that reduced plutonium is favorably removed from soil. Americium, however, does not require a strong reducing environment to be removed from soil. Column leaching results confirm that reducing agents can significantly enhance the removal of radioactivity and batch extraction data is generally applicable to column leaching process. With a reducing agent, the temperature is found to have little effect on removal. However, using a citrate solution alone and increasing the temperature can double the efficiency of radionuclide removal. Radioanalytical results demonstrate no difference in extracting efficiency for plutonium isotopes during the removal processes.
