Bioreduction of U(VI)-Phthalate to a Polymeric U(IV)-Phthalate Colloid
Phthalic acid, a ubiquitous organic ligand, formed soluble mono- and biligand complexes with a uranyl ion that was then reduced to a U(IV)-phthalate by a Clostridium species under anaerobic conditions. We confirmed the reduction of the hexavalent uranium to the tetravalent oxidation state by UV-vis absorption and X-ray absorption near edge structure spectroscopy. Sequential micro- and ultrafiltration of the solution revealed that the bioreduced uranium was present as a colloid with particles between 0.03 and 0.45 {mu}m. Analysis with extended X-ray absorption fine structure revealed the association of the reduced uranium with the phthalic acid as a repeating biligand 1:2 U(IV):phthalic acid polymer. This is the first report of the formation of a U(IV) complexed to two phthalic acid molecules in the form of a polymeric colloid. Although it was proposed that the bioreduction and the precipitation of uranium might be an invaluable strategy to immobilize uranium in contaminated environments, our results suggest that the organic ligands present there might hinder the precipitation of the bioreduced uranium under anaerobic conditions and, thereby, enhance its environmental mobility as uranium organic complexes or colloids.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 980044
- Report Number(s):
- BNL-92962-2010-JA; INOCAJ; TRN: US1005402
- Journal Information:
- Inorganic Chemistry, Vol. 48, Issue 19; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ABSORPTION
ANAEROBIC CONDITIONS
CLOSTRIDIUM
COLLOIDS
COMPLEXES
FINE STRUCTURE
IONS
LIGANDS
MOBILITY
MOLECULES
PARTICLES
PHTHALIC ACID
PRECIPITATION
REDUCTION
SOLUTIONS
SPECTROSCOPY
ULTRAFILTRATION
URANIUM
VALENCE
national synchrotron light source