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dc.contributor.authorStewart, B. D.
dc.contributor.authorGiradot, Crystal L.
dc.contributor.authorSpycher, Nicolas
dc.contributor.authorSani, Rajesh K.
dc.contributor.authorPeyton, Brent M.
dc.identifier.citationStewart BD, Girardot C, Spycher N, Sani RK, Peyton BM, "Influence of chelating agents on biogenic uraninite reoxidation by Fe(III) (Hydr)oxides," Environmental Science & Technology, January 2013 47(1):364−371.en_US
dc.description.abstractMicrobially mediated reduction of soluble U(VI) to U(IV) with subsequent precipitation of uraninite, UO2(S), has been proposed as a method for limiting uranium (U) migration. However, microbially reduced UO2 may be susceptible to reoxidation by environmental factors, with Fe(III) (hydr)oxides playing a significant role. Little is known about the role that organic compounds such as Fe(III) chelators play in the stability of reduced U. Here, we investigate the impact of citrate, DFB, EDTA, and NTA on biogenic UO2 reoxidation with ferrihydrite, goethite, and hematite. Experiments were conducted in anaerobic batch systems in PIPES buffer (10 mM, pH 7) with bicarbonate for approximately 80 days. Results showed EDTA accelerated UO2 reoxidation the most at an initial rate of 9.5 μM day−1 with ferrihydrite, 8.6 μM day−1 with goethite, and 8.8 μM day−1 with hematite. NTA accelerated UO2 reoxidation with ferrihydrite at a rate of 4.8 μM day−1; rates were less with goethite and hematite (0.66 and 0.71 μM day−1, respectively). Citrate increased UO2 reoxidation with ferrihydrite at a rate of 1.8 μM day−1, but did not increase the extent of reaction with goethite or hematite, with no reoxidation in this case. In all cases, bicarbonate increased the rate and extent of UO2 reoxidation with ferrihydrite in the presence and absence of chelators. The highest rate of UO2 reoxidation occurred when the chelator promoted both UO2 and Fe(III) (hydr)oxide dissolution as demonstrated with EDTA. When UO2 dissolution did not occur, UO2 reoxidation likely proceeded through an aqueous Fe(III) intermediate with lower reoxidation rates observed. Reaction modeling suggests that strong Fe(II) chelators promote reoxidation whereas strong Fe(III) chelators impede it. These results indicate that chelators found in U contaminated sites may play a significant role in mobilizing U, potentially affecting bioremediation efforts.en_US
dc.titleInfluence of chelating agents on biogenic uraninite reoxidation by Fe(III) (Hydr)oxidesen_US
mus.citation.journaltitleEnvironmental Science & Technologyen_US
mus.identifier.categoryChemical & Material Sciencesen_US
mus.identifier.categoryEngineering & Computer Scienceen_US
mus.identifier.categoryLife Sciences & Earth Sciencesen_US
mus.relation.collegeCollege of Agricultureen_US
mus.relation.collegeCollege of Engineeringen_US
mus.relation.collegeCollege of Letters & Scienceen_US
mus.relation.departmentCenter for Biofilm Engineering.en_US
mus.relation.departmentChemical & Biological Engineering.en_US
mus.relation.departmentChemistry & Biochemistry.en_US
mus.relation.departmentMicrobiology & Immunology.en_US
mus.relation.universityMontana State University - Bozemanen_US
mus.relation.researchgroupCenter for Biofilm Engineering.en_US
mus.contributor.orcidPeyton, Brent M.|0000-0003-0033-0651en_US

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