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Poulain A, Fernandez-Martinez A, Greneche JM, Prieur D, Scheinost AC, Menguy N, Bureau S, Magnin V, Findling N, Drnec J, Martens I, Mirolo M, Charlet L. Selenium Nanowire Formation by Reacting Selenate with Magnetite. Environ Sci Technol 2022; 56:14817-14827. [PMID: 36184803 DOI: 10.1021/acs.est.1c08377] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The mobility of 79Se, a fission product of 235U and long-lived radioisotope, is an important parameter in the safety assessment of radioactive nuclear waste disposal systems. Nonradioactive selenium is also an important contaminant of drainage waters from black shale mountains and coal mines. Highly mobile and soluble in its high oxidation states, selenate (Se(VI)O42-) and selenite (Se(IV)O32-) oxyanions can interact with magnetite, a mineral present in anoxic natural environments and in steel corrosion products, thereby being reduced and consequently immobilized by forming low-solubility solids. Here, we investigated the sorption and reduction capacity of synthetic nanomagnetite toward Se(VI) at neutral and acidic pH, under reducing, oxygen-free conditions. The additional presence of Fe(II)aq, released during magnetite dissolution at pH 5, has an effect on the reduction kinetics. X-ray absorption spectroscopy analyses revealed that, at pH 5, trigonal gray Se(0) formed and that sorbed Se(IV) complexes remained on the nanoparticle surface during longer reaction times. The Se(0) nanowires grew during the reaction, which points to a complex transport mechanism of reduced species or to active reduction sites at the tip of the Se(0) nanowires. The concomitant uptake of aqueous Fe(II) and Se(VI) ions is interpreted as a consequence of small pH oscillations that result from the Se(VI) reduction, leading to a re-adsorption of aqueous Fe(II) onto the magnetite, renewing its reducing capacity. This effect is not observed at pH 7, where we observed only the formation of Se(0) with slow kinetics due to the formation of an oxidized maghemite layer. This indicates that the presence of aqueous Fe(II) may be an important factor to be considered when examining the environmental reactivity of magnetite.
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Affiliation(s)
- Agnieszka Poulain
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000Grenoble, France
| | | | - Jean-Marc Greneche
- Institut des Molécules et Matériaux du Mans, CNRS UMR-6283, Le Mans Université, F-72085Le Mans, France
| | - Damien Prieur
- The Rossendorf Beamline at ESRF, 71 avenue des Martyrs, 38043 Grenoble, France and HZDR Institute of Resource Ecology, Bautzener Landstrasse 400, 01328Dresden, Germany
| | - Andreas C Scheinost
- The Rossendorf Beamline at ESRF, 71 avenue des Martyrs, 38043 Grenoble, France and HZDR Institute of Resource Ecology, Bautzener Landstrasse 400, 01328Dresden, Germany
| | - Nicolas Menguy
- Sorbonne Université, Muséum National d'Histoire Naturelle, UMR CNRS 7590, IRD. Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 Place Jussieu, 75005Paris, France
| | - Sarah Bureau
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000Grenoble, France
| | - Valérie Magnin
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000Grenoble, France
| | - Nathaniel Findling
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000Grenoble, France
| | - Jakub Drnec
- ESRF, 71 avenue des Martyrs, 38043Grenoble, France
| | | | - Marta Mirolo
- ESRF, 71 avenue des Martyrs, 38043Grenoble, France
| | - Laurent Charlet
- Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000Grenoble, France
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