Effect of Fulvic Acid Surface Coatings on Plutonium Sorption and Desorption Kinetics on Goethite

The rates and extent of plutonium (Pu) sorption and desorption onto mineral surfaces are important parameters for predicting Pu mobility in subsurface environments. The presence of natural organic matter, such as fulvic acid (FA), may influence these parameters. We investigated the effects of FA on...

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Bibliographic Details
Published in:Environmental science & technology 2015-03, Vol.49 (5), p.2776-2785
Main Authors: Tinnacher, Ruth M, Begg, James D, Mason, Harris, Ranville, James, Powell, Brian A, Wong, Jennifer C, Kersting, Annie B, Zavarin, Mavrik
Format: Article
Language:English
Subjects:
Adsorption
Benzopyrans - chemistry
Desorption
Ecology
Effects
fulvic acid
Iron Compounds - chemistry
Kinetics
Minerals
Minerals - chemistry
natural organic matter
Plutonium
Plutonium - chemistry
RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
Sorption
surface coating
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Summary:The rates and extent of plutonium (Pu) sorption and desorption onto mineral surfaces are important parameters for predicting Pu mobility in subsurface environments. The presence of natural organic matter, such as fulvic acid (FA), may influence these parameters. We investigated the effects of FA on Pu­(IV) sorption/desorption onto goethite in two scenarios: when FA was (1) initially present in solution or (2) found as organic coatings on the mineral surface. A low pH was used to maximize FA coatings on goethite. Experiments were combined with kinetic modeling and speciation calculations to interpret variations in Pu sorption rates in the presence of FA. Our results indicate that FA can change the rates and extent of Pu sorption onto goethite at pH 4. Differences in the kinetics of Pu sorption were observed as a function of the concentration and initial form of FA. The fraction of desorbed Pu decreased in the presence of FA, indicating that organic matter can stabilize sorbed Pu on goethite. These results suggest that ternary Pu–FA–mineral complexes could enhance colloid-facilitated Pu transport. However, more representative natural conditions need to be investigated to quantify the relevance of these findings.
ISSN:0013-936X
1520-5851
DOI:10.1021/es505120s