REDUCTION OF URANIUM(VI) UNDER SULFATE-REDUCING CONDITIONS IN THE PRESENCE OF FE(III)-(HYDR)OXIDES
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dc.contributor.author | Sani R.K. | |
dc.contributor.author | Peyton B.M. | |
dc.contributor.author | Amonette J.E. | |
dc.contributor.author | Geesey G.G. | |
dc.date.accessioned | 2022-03-21T07:44:17Z | |
dc.date.available | 2022-03-21T07:44:17Z | |
dc.date.issued | 2004 | |
dc.identifier | https://www.elibrary.ru/item.asp?id=12090555 | |
dc.identifier.citation | Geochimica et Cosmochimica Acta, 2004, 68, 12, 2639-2648 | |
dc.identifier.issn | 0016-7037 | |
dc.identifier.uri | https://repository.geologyscience.ru/handle/123456789/36514 | |
dc.description.abstract | Hexavalent uranium [U(VI)] dissolved in a modified lactate-C medium was treated under anoxic conditions with a mixture of an Fe(III)-(hydr)oxide mineral (hematite, goethite, or ferrihydrite) and quartz. The mass of Fe(III)-(hydr)oxide mineral was varied to give equivalent Fe(III)-mineral surface areas. After equilibration, the U(VI)-mineral suspensions were inoculated with sulfate-reducing bacteria, Desulfovibrio desulfuricans G20. Inoculation of the suspensions containing sulfate-limited medium yielded significant G20 growth, along with concomitant reduction of sulfate and U(VI) from solution. With lactate-limited medium, however, some of the uranium that had been removed from solution was resolubilized in the hematite treatments and, to a lesser extent, in the goethite treatments, once the lactate was depleted. No resolubilization was observed in the lactate-limited ferrihydrite treatment even after a prolonged incubation of 4 months. Uranium resolubilization was attributed to reoxidation of the uraninite by Fe(III) present in the (hydr)oxide phases. Analysis by U L3-edge XANES spectroscopy of mineral specimens sampled at the end of the experiments yielded spectra similar to that of uraninite, but having distinct features, notably a much more intense and slightly broader white line consistent with precipitation of nanometer-sized particles. The XANES spectra thus provided strong evidence for SRB-promoted removal of U(VI) from solution by reductive precipitation of uraninite. Consequently, our results suggest that SRB mediate reduction of soluble U(VI) to an insoluble U(IV) oxide, so long as a suitable electron donor is available. Depletion of the electron donor may result in partial reoxidation of the U(IV) to soluble U(VI) species when the surfaces of crystalline Fe(III)-(hydr)oxides are incompletely reduced. | |
dc.title | REDUCTION OF URANIUM(VI) UNDER SULFATE-REDUCING CONDITIONS IN THE PRESENCE OF FE(III)-(HYDR)OXIDES | |
dc.type | Статья |
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