Graduate Research and Discovery Symposium (GRADS)

Advisor

Brian A. Powell

Document Type

Poster

Department

Environmental Engineering and Science

Publication Date

Spring 2013

Abstract

While it has been noted previously that the reversibility of actinide sorption decreases over time, this study demonstrates the aging effects on 32-year versus 3-day-old plutonium complexes simultaneously using dual isotopes on Savannah River Site sediment exposed to plutonium 32 years ago [Kaplan, et al., 2006]. These experiments demonstrate the aging effects through batch sorption and desorption experiments (for 3, 7 and 28 days) and selective iron extractions in the presence of a variety of inorganic and organic ligands including: NaCl, CaCl2, Na2PO4, NaF, Citric Acid, Fulvic Acid, DFOB, H2O2, or NH2OH.HCl. The resulting average desorption Kd at pH 6.4±0.4 is 51000±40000 mL/g. Despite the variability of the Kd values measured in this study, it is remarkable that the desorption Kd is not more variable with the diverse ligands investigated. The selective iron extractions illustrate an aging effect of the plutonium complexes with 22±2% versus 91±14% of the plutonium removed for the 32-year and 3-day exposures, respectively. While the plutonium isotopes are most likely mobilized by the specific conditions of the extractions rather than being associated with the iron fraction, it shows that the 3-day-old complex is not nearly as strong as that after 32 years of aging.

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