Biotic Fe(III) reduction of magnetite coupled to H2 oxidation: Implication for radioactive waste geological disposal

Marta K Schütz (1) , Olivier Bildstein (2, 3) , Michel L Schlegel (4, 3) , Marie Libert (2, 3)

1 CINaM - Centre Interdisciplinaire de Nanoscience de Marseille
2 LMTE - Laboratoire de Modélisation des Transferts dans l'Environnement
3 CEA-DES (ex-DEN) - CEA-Direction des Energies (ex-Direction de l'Energie Nucléaire)
4 SEARS - Service d'études analytiques et de réactivité des surfaces

We report the first results on microbial Fe (III) reduction of magnetite in the presence of H2 (4 per cent, 10 per cent, or 60 per cent H2) as the sole electron donor. The H2 concentration is the parameter likely to control both chemical and biological dissolution of magnetite, and a direct correlation between H2 concentration, bacterial activity, and the extent of Fe(III) bioreduction was observed. Vivianite was identified as a secondary mineral phase as a consequence of the increase in dissolved Fe(II) and the presence of phosphate in the experimental solutions. In the context of metal corrosion, Fe(III) bioreduction coupled to H2 oxidation may affect the passivating properties of oxide layers made of magnetite.

Keywords: Iron-reducing bacteria; Magnetite; Hydrogen; Ferrozine assay; Geological disposal

Domains: Nuclear Theory [nucl-th]; Nuclear Experiment [nucl-ex]

Marta K Schütz, Olivier Bildstein, Michel L Schlegel, Marie Libert. Biotic Fe(III) reduction of magnetite coupled to H2 oxidation: Implication for radioactive waste geological disposal. Chemical Geology, 2015, 419, pp.67-74. ⟨10.1016/j.chemgeo.2015.10.039⟩. ⟨cea-02383215⟩