Investigation of Wüstite (FeO) Dissolution : Implications for Reductive Dissolution of Ferric Oxides

The pH-dependent dissolution flux of FeO (wüstite, a ferrous oxide) was measured in this study; flux = k{H+}n (moV/m2/s), where k = 10(-4.95) and n = 0.64. This flux was consistent with theoretical predictions based on the rate of water exchange of hexaaquo Fe2+. Interestingly, when compared to publ...

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Bibliographic Details
Published in:Environmental science & technology 2009-02, Vol.43 (4), p.1086-1090
Main Authors: JANG, Je-Hun, BRANTLEY, Susan L
Format: Article
Language:English
Subjects:
Applied sciences
Bacteria
Chemical engineering
Dissolution
Exact sciences and technology
Ferric Compounds - chemistry
Ferrous Compounds - chemistry
Hydrogen-Ion Concentration
Iron
Models, Chemical
Oxidation-Reduction
Pollution
Reproducibility of Results
Solubility
Spectroscopy, Mossbauer
Studies
Surface Properties
X-Ray Diffraction
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Summary:The pH-dependent dissolution flux of FeO (wüstite, a ferrous oxide) was measured in this study; flux = k{H+}n (moV/m2/s), where k = 10(-4.95) and n = 0.64. This flux was consistent with theoretical predictions based on the rate of water exchange of hexaaquo Fe2+. Interestingly, when compared to published data, the pH-dependent dissolution flux of FeO defined an upper limit for the reductive dissolution fluxes of iron(III) (oxyhydr)oxides, including bacterial dissimilatory iron reduction (DIR). A wide range of dissolution fluxes across several orders of magnitude has been reported for iron(III) (oxyhydr)oxides in the literature and the fluxes were affected by various experimental variables, e.g., pH, ligands, chemical reductants, and bacteria. We concluded that (i) the reductive dissolution fluxes of iron(III) (oxyhydr)oxides, including bacterial DIR, are ultimately bracketed by the detachment rate of reduced Fe(II) from the surface and (ii) the maximum flux can be approached when the mole fraction of reduced Fe(II) at the surface is close to unity.
ISSN:0013-936X
1520-5851
DOI:10.1021/es8010139