Ferrihydrite dissolution by pyridine-2,6-bis(monothiocarboxylic acid) and hydrolysis products

Dhungana, Suraj; Anthony, Charles R.; Hersman, Larry E.

doi:10.1016/j.gca.2007.07.022

Cited by 14 publications

(13 citation statements)

References 42 publications

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“…From the time scale of the transformation reactions observed, the total Fe present in the capillary tube system and assuming a surface area of 600 m 2 /g, the minimum dissolution rate of 6-line ferrihydrite is estimated to be 1.310 -10 and 2.510 -11 mol/m 2 /s for transformation taking place at 18 and 1.8 mM Fe(II) injections respectively. These rates would be comparable to the reported values of ferrihydrite dissolution by strong reducing agents (such as 10 mM ascorbic acid) or microbially-produced chelators (14,15), and are too rapid for a system lacking such chelating agents at circumneutral pH and 25ºC. Furthermore, there was no statistically distinguishable difference between input and effluent solution Fe chemistry by ICP-MS analysis.…”

Section: Evaluation Of Dissolution-precipitation and Surface Adsorptisupporting

confidence: 70%

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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Section: Evaluation Of Dissolution-precipitation and Surface Adsorptisupporting

confidence: 70%

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 ymp strain was also shown to have endogenous Fe(III)-reducing activity, which Hersman et al suggested could be involved in solubilizing ferric minerals (24). Likewise, closely related strains of Pseudomonas stutzeri have been shown to produce pyridine-2,6-bis(thiocarboxylic acid) (PDTC), which they can use in the reduction, transport, and detoxification of metals and metalloids (11,16,51). However, control experiments showed that P. mendocina did not secrete molecules that exhibited a significant amount of reducing activity under the conditions used in this study (see the supplemental material).…”

Section: Is 10mentioning

confidence: 83%

Roles of Siderophores, Oxalate, and Ascorbate in Mobilization of Iron from Hematite by the Aerobic Bacterium Pseudomonas mendocina

Dehner

Awaya

Maurice

et al. 2010

Appl Environ Microbiol

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“…Reduction of iron can serve to facilitate the solubilization of the metal in the environment, as iron(II) has higher solubility and lower Brønsted acidity than iron(III), as well as more rapid ligand exchange rates (Dhungana et al 2007). Siderophores also have a reasonable affinity for iron(II), and stabilization of the iron in the 3?…”

Section: Redox Control By Chelationmentioning

confidence: 99%

The redox hypothesis in siderophore-mediated iron uptake

Harrington

Crumbliss

2009

Biometals

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Ferrihydrite dissolution by pyridine-2,6-bis(monothiocarboxylic acid) and hydrolysis products

Cited by 14 publications

References 42 publications

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

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

Roles of Siderophores, Oxalate, and Ascorbate in Mobilization of Iron from Hematite by the Aerobic Bacterium Pseudomonas mendocina

The redox hypothesis in siderophore-mediated iron uptake

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