Bacterial siderophores promote dissolution of UO2 under reducing conditions
- Autor(en)
- Scot Frazier, Ruben Kretzschmar, Stephan Krämer
- Abstrakt
Tetravalentactinides are often considered environmentally immobile due to their strong hydrolysis and formation of sparingly soluble oxide phases. However, biogenic ligands commonly found in the soil environment may increase their solubility and mobility. We studied the adsorption and dissolution kinetics of UO2 in the presence of a microbial siderophore, desferrioxamine-B (DFO-B), under reducing conditions. Using batch and continuous flow stirred tank reactors (CFSTR), we found that OFO-B increases the solubility of UIV and accelerates UO2 dissolution rates through a ligand-promoted dissolution mechanism. OFO-B adsorption to UO 2 followed a Langmuir-type isotherm. The maximum adsorbed DFO-B concentrations were 3.3 ?mol-2 between pH 3 and 8 and declined above pH 8. OFO-B dissolved UO2 at a OFO-B surface-saturated net rate of 64 nmol h-1 m-2 (pH 7.5, I = 0.01 M) according to the first-order rate equation R = kL[Lads], with a rate coefficient kL of 0.019 h-1. Even at very low siderophore concentrations (e.g. 1 ?M), net dissolution rates (16 nmol h-1 m-2, pH 7.5, I = 0.01 M) were substantially greaterthan net proton-promoted dissolution rates (3 nmol h-1 m-2, pH 7-7.5, I = 0.01 M). Interestingly, adding dissolved FeIII had negligible effects on DFO-B-promoted UO2 dissolution rates, despite its potential as a competitor for DFO-B and as an oxidant of UIV. Our results suggest that strong organic ligands could influence the environmental mobility of tetravalent actinides and should be considered in predictions for nuclear waste storage and remediation strategies. © 2005 American Chemical Society.
- Organisation(en)
- Externe Organisation(en)
- Eidgenössische Technische Hochschule Zürich
- Journal
- Environmental Science & Technology
- Band
- 39
- Seiten
- 5709-5715
- Anzahl der Seiten
- 6
- ISSN
- 0013-936X
- DOI
- https://doi.org/10.1021/es050270n
- Publikationsdatum
- 2005
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105105 Geochemie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/9748336f-458c-44a0-a0c0-369b297fa64f