Journal ArticleDOI
Spectroscopic Evidence for Fe(II)−Fe(III) Electron Transfer at the Iron Oxide−Water Interface
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TLDR
Spectroscopic observations of Fe(II) reacted with oxide surfaces under conditions typical of natural environments suggest a novel pathway for the biogeochemical cycling of Fe and also raises important questions regarding the mechanism of contaminant reduction by Fe (II) in the presence of oxide surfaces.Abstract:
Using the isotope specificity of 57Fe Mossbauer spectroscopy, we report spectroscopic observations of Fe(II) reacted with oxide surfaces under conditions typical of natural environments (i.e., wet, anoxic, circumneutral pH, and about 1% Fe(II)). Mossbauer spectra of Fe(II) adsorbed to rutile (TiO2) and aluminum oxide (Al2O3) show only Fe(II) species, whereas spectra of Fe(II) reacted with goethite (α-FeOOH), hematite (α-Fe2O3), and ferrihydrite (Fe5HO8) demonstrate electron transfer between the adsorbed Fe(II) and the underlying iron(III) oxide. Electron-transfer induces growth of an Fe(III) layer on the oxide surface that is similar to the bulk oxide. The resulting oxide is capable of reducing nitrobenzene (as expected based on previous studies), but interestingly, the oxide is only reactive when aqueous Fe(II) is present. This finding suggests a novel pathway for the biogeochemical cycling of Fe and also raises important questions regarding the mechanism of contaminant reduction by Fe(II) in the presenc...read more
Citations
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Journal ArticleDOI
Biogeochemical Redox Processes and their Impact on Contaminant Dynamics
Thomas Borch,Ruben Kretzschmar,Andreas Kappler,Philippe Van Cappellen,Matthew Ginder-Vogel,Andreas Voegelin,Kate M. Campbell +6 more
TL;DR: Recent advances in the understanding of biogeochemical redox processes are highlighted and their impact on contaminant fate and transport, including future research needs are highlighted.
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Relation between the redox state of iron-based nanoparticles and their cytotoxicity toward Escherichia coli.
Mélanie Auffan,Wafa Achouak,Jérôme Rose,Marie-Anne Roncato,Corinne Chanéac,David T. Waite,Armand Masion,Joseph C. Woicik,Mark R. Wiesner,Jean-Yves Bottero +9 more
TL;DR: The aim of this study was to understand the relationship between the redox state of iron-based nanoparticles and their cytotoxicity toward a Gram-negative bacterium, Escherichia coli.
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Fast transformation of iron oxyhydroxides by the catalytic action of aqueous Fe(II)
TL;DR: In this paper, the isotopic exchange between aqueous Fe(II) and iron oxides was investigated using isotope exchange experiments with 55Fe-labeled IR oxides.
Journal ArticleDOI
The Iron Isotope Fingerprints of Redox and Biogeochemical Cycling in Modern and Ancient Earth
TL;DR: The largest Fe isotope fractionations occur during redox changes, as well as differences in bonding, but these are expressed only in natural environments in which significant quantities of Fe may be mobilized and separated as discussed by the authors.
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Geomicrobiological cycling of iron
TL;DR: The active metabolic processes outlined above have to be distinguished from indirect biologically induced iron mineral formation in which prokaryotic cell surfaces simply act as passive templates (“passive iron biomineralization”) (e.g., Konhauser 1997).
References
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BookDOI
Mössbauer spectroscopy applied to inorganic chemistry
Gary J. Long,Fernande Grandjean +1 more
TL;DR: The early days of the effect of Mossbauer spectroscopy on hard magnetic materials are described in this paper... and the potential of using it in the field of biological mineralization is discussed.
Journal ArticleDOI
Surface catalysis of uranium(VI) reduction by iron(II)
TL;DR: In this article, the authors investigated the kinetic effect of specific adsorption interactions on the chemical reduction of uranyl (UVIO22+) by ferrous iron, and derived a rate law for surface-catalyzed U(VI) reduction by Fe(II), d[U(VI)] dt =−k[≡ Fe III OFe II OH 0 ][U( VI)] ads where the bimolecular rate constant k has a value of 399 ± 25 M−1 min−1 at 25°C.
Journal ArticleDOI
The cycling of iron in natural environments : considerations based on laboratory studies of heterogeneous redox processes
Werner Stumm,Barbara Sulzberger +1 more
TL;DR: The various pathways for the oxygenation of ferrous iron and for the dissolution of Fe(III) (hydr) oxides, especially by reducing ligands with oxygen donor atoms in thermal and photochemical processes, are assessed on the basis of laboratory experiments for application to natural systems.
Journal ArticleDOI
Voigt-based methods for arbitrary-shape static hyperfine parameter distributions in Mössbauer spectroscopy
Denis G. Rancourt,J.Y. Ping +1 more
TL;DR: In this article, the authors introduce a powerful approach for obtaining arbitrary-shape static hyperfine parameter distributions from thickness corrected Mossbauer spectra. The distributions are taken as sums of Gaussian components and the corresponding spectra are shown analytically to be sums of Voigt lines.
Journal ArticleDOI
Reduction of Substituted Nitrobenzenes by Fe(II) in Aqueous Mineral Suspensions.
TL;DR: The results of this study demonstrate that Fe(ll) adsorbed on iron (hydr)oxide surfaces or surface coatings may play an important role in the reductive transformation of organic pollutants in subsurface environments.
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