Transformation of ferric hydroxide into spinel by iron(II) adsorption

Tronc, E.; Belleville, Philippe; Jolivet, Jean‐Pierre; Livage, Jacques

doi:10.1021/la00037a057

Cited by 259 publications

(268 citation statements)

References 6 publications

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“…Operating conditions effectively avoided oxidation. The addition of Fe(II) after the precipitation of Fe(III) yielded the same features as coprecipitation, as reported earlier (Tronc et al, 1992).…”

Section: Resultssupporting

confidence: 82%

“…Ferrihydrite dissolves quasi-instantaneously at the pH conditions used, while magnetite dissolves more slowly regardless of the particle size and the Fe(II)/Fe(III) ratio (Tronc et aL, 1992).…”

Section: Influence Of the Level Of Fe(ii)mentioning

confidence: 94%

“…We recently reported (Tronc et al, 1992) that Fe(II) ions in alkaline medium (pH ~ 11) can also make ferrihydrite convert to a spinel phase by a reaction in the solid state. Fe(II) adsorption induces an interfacial electron transfer and the mobility of the extra electrons within the whole Fe(II)-ferrihydrite particle drives the transformation.…”

Section: Introductionmentioning

confidence: 99%

“…A similar effect also occurs at pH 5-7 (Fischer, 1973). At x > 0.1 (Tronc et al, 1992), goethite formation is totally suppressed and both Copyright 9 1992, The Clay Minerals Society reactions, in the solid state and via the solution, lead to stable (nonstoichiometric) magnetites which can be morphologically very distinct.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Fe(II) on the Formation of the Spinel Iron Oxide in Alkaline Medium

Jolivet

Belleville

Tronc

et al. 1992

Clays and clay miner.

132

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Fe(II) and Fe(III) in various proportions were coprecipitated by NH3 at pH ≈ 11. The Fe(II)/Fe(III) ratio (x) was varied from 0.10 to 0.50. After stabilization by aging at pH ≃ 8 in anaerobic conditions, hydrous precipitates were characterized by electron microscopy, Mössbauer spectroscopy, and kinetics of dissolution in acidic medium. At any x value, all stable products exhibited the structure of (oxidized) magnetite. For x ≤ 0.30, two distinct species were coexisting: the one (“m”) was made up of ca. 4nm-sized particles with a low Fe(II) content (Fe(II)/Fe(III) ≈ 0.07), and the other (“M”) consisted of particles of larger, more or less distributed sizes, and composition Fe(II)/Fe(III) ≈ 0.33; “M” increased relative amount with increasing x. For x ≥ 0.35, “M” was the only constituent and its Fe(II)/Fe(III) ratio was equal to x. “M” is identified with (nonstoichiometric) magnetite, whereas “m” is likely to be an oxyhydroxide. Mechanisms of formation are discussed, and a phase diagram is proposed which schematizes the evolution of the coprecipitation products with x and with time. Addition of Fe(II) after the precipitation of Fe(III), instead of coprecipitation, yielded very similar results.

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Section: Resultssupporting

confidence: 82%

Section: Influence Of the Level Of Fe(ii)mentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Influence of Fe(II) on the Formation of the Spinel Iron Oxide in Alkaline Medium

Jolivet

Belleville

Tronc

et al. 1992

Clays and clay miner.

132

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“…For the magnetite formation observed in this study, another possible reaction mechanism is through oxidation and precipitation of the adsorbed ferrous ions on ferrihydrite particle surfaces via interfacial electron transfer reactions as suggested by Tronc et al (5). The existence of such interfacial electron transfer reactions between adsorbed Fe(II) and iron oxides has been experimentally confirmed by Williams and Scherer (16) and Larese-Casanova et al (17) with Mossbauer spectroscopy.…”

Section: Evaluation Of Dissolution-precipitation and Surface Adsorptisupporting

confidence: 75%

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Yang

Steefel

Marcus

et al. 2010

Environ. Sci. Technol.

137

138

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The readsorption of ferrous ions produced by the abiotic and microbially-mediated reductive dissolution of iron oxy-hydroxides drives a series of transformations of the host minerals. To further understand the mechanisms by which these transformations occur and their kinetics within a microporous flow environment, flow-through experiments were conducted in which capillary tubes packed with ferrihydrite-coated glass spheres were injected with inorganic Fe(II) solutions under circumneutral pH conditions at 25ºC. Synchrotron X-ray diffraction was used to identify the secondary phase(s) formed and to provide data for quantitative kinetic analysis. At concentrations at and above 1.8 mM Fe(II) in the injection solution, magnetite was the only secondary phase formed (no intermediates were detected), with complete transformation following a nonlinear rate law requiring 28 hours and 150 hours of reaction at 18 and 1.8 mM Fe(II), respectively. However, when the injection solution consisted of 0.36 mM Fe(II), goethite was the predominant reaction product and formed much more slowly according to a linear rate law, while only minor magnetite was formed. When the rates are normalized based on the time to react half of the ferrihydrite on a reduced time plot, it is apparent that the 1.8 mM and 18 mM input Fe(II) experiments can be described by the same reaction mechanism, while the 0.36 input Fe(II) experiment is distinct. The analysis of the transformation kinetics suggest that the transformations involved an electron transfer reaction between the aqueous as well as sorbed Fe(II) and ferrihydrite acting as a semiconductor, rather than a simple dissolution and recrystallization mechanism. A transformation mechanism involving sorbed inner sphere Fe(II) alone is not supported, since the essentially equal coverage of sorption sites in the 18 mM and 1.8 mM Fe(II) injections cannot explain the difference in the transformation rates observed.

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Palladium Catalyst Systems for Cross-Coupling Reactions of Aryl Chlorides and Olefins

Zapf¹,

Beller²

2001

Chem. Eur. J.

135

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A detailed investigation into the influence of phosphines, additives, bases and solvents on the Heck coupling reaction of 4-trifluoromethyl-1-chlorobenzene (2) is presented. It is shown that a number of catalyst systems exist for efficient cross coupling of electron-deficient aryl chlorides with various olefins. Basicity and steric demand of the ligand are two factors which determine the success of the reaction. In addition the phosphine/palladium ratio, the correct type and amount of additive, and finally the use of an appropriate base and solvent are also important. The optimised reaction conditions are applied for the arylation of styrene, 2-ethylhexyl acrylate and N,N-dimethyl acrylic amide with various aryl chlorides.

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Transformation of ferric hydroxide into spinel by iron(II) adsorption

Cited by 259 publications

References 6 publications

Influence of Fe(II) on the Formation of the Spinel Iron Oxide in Alkaline Medium

Influence of Fe(II) on the Formation of the Spinel Iron Oxide in Alkaline Medium

Kinetics of Fe(II)-Catalyzed Transformation of 6-line Ferrihydrite under Anaerobic Flow Conditions

Palladium Catalyst Systems for Cross-Coupling Reactions of Aryl Chlorides and Olefins

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