Reoxidation of Reduced Uranium with Iron(III) (Hydr)Oxides under Sulfate-Reducing Conditions

Journal Article · Fri Mar 04 00:00:00 EST 2005 · Environmental Science and Technology, 39(7):2059-2066

DOI:https://doi.org/10.1021/es0494297· OSTI ID:15020662

Sani, Rajesh K; Peyton, Brent M; Dohnalkova, Alice; Amonette, James E

In cultures of Desulfovibrio desulfuricansG20 the effects of iron(III) (hydr)oxides (hematite, goethite, and ferrihydrite) on microbial reduction and reoxidation of uranium (U) were evaluated under lactate-limited sulfate-reducing conditions. With lactate present, G20 reduced U(VI) in both 1,4-piperazinediethanesulfonate (PIPES) and bicarbonate buffer. Once lactate was depleted, however, microbially reduced U served as an electron donor to reduce Fe(III) present in iron(III) (hydr)oxides. With the same initial amount of Fe(III) (10 mmol/L) for each iron(III) (hydr)oxide,reoxidation of U(IV) was greater with hematite than with goethite or ferrihydrite. As the initial mass loading of hematite increased from 0 to 20 mmol of Fe(III)/L, the rate and extent of U(IV) reoxidation increased. Subsequent addition of hematite [15 mmol of Fe(III)/L] to stationary-phase cultures containing microbially reduced U(IV) also resulted in rapid reoxidation to U(VI). Analysis by U L3-edge X-ray absorption near-edge spectroscopy (XANES) of microbially reduced U particles yielded spectra similar to that of natural uraninite. Observations by high-resolution transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray spectroscopic analysis confirmed that precipitated U associated with cells was uraninite with particle diameters of 3-5 nm. By the same techniques, iron sulfide precipitates were found to have a variable Fe and S stoichiometry and were not associated with cells.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 15020662
• Report Number(s): PNNL-SA-45281; KP1704020; KP1301010; KP1301010; TRN: US200625%%154
• Journal Information: Environmental Science and Technology, 39(7):2059-2066, Journal Name: Environmental Science and Technology, 39(7):2059-2066
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
ABSORPTION
ACID CARBONATES
BINDING ENERGY
DESULFOVIBRIO
ELECTRON DIFFRACTION
ELECTRONS
GOETHITE
HEMATITE
IRON SULFIDES
LACTATES
SPECTRA
SPECTROSCOPY
STOICHIOMETRY
TRANSMISSION ELECTRON MICROSCOPY
URANINITES
URANIUM
VALENCE
uranium reduction
bacterial reduction
remediation
sulfate-reducing bacteria
iron oxide
hematite
X-ray absorption spectroscopy
electron microscopy
XANES
TEM