Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

Eitel, Eryn M.; Taillefert, Martial

doi:10.1016/j.gca.2017.07.016

Cited by 16 publications

(20 citation statements)

References 55 publications

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“…The formation kinetics of the disulfide product followed the order of disappearance of their corresponding thiol: Cystamine reached equilibrium concentrations after 2.5 min, followed by cystine (4 min), homocystine (12.5 min), and oxidized glutathione (16 min). In general, the reaction rates of thiols with Mn oxides were significantly higher than the previously reported reaction rates of thiols with ferrihydrite under identical conditions . Reactions between cysteamine and 1.5-year-old δ-MnO 2 resulted in a half-life 33 times shorter than that of cysteamine reaction with ferrihydrite.…”

Section: Resultscontrasting

confidence: 56%

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Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Eitel

Zhao

Tang

et al. 2018

Environ. Sci. Technol.

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The kinetics and mechanism of thiol oxidation by Mn oxides undergoing dynamic structural transformation under environmentally relevant conditions remain poorly understood. In this study, thiol/disulfide pair concentrations were simultaneously determined in situ using voltammetric microelectrodes during the interaction of four common thiols (cysteine, homocysteine, cysteamine, and glutathione) with fresh and aged δ-MnO 2 at pH 7.0. The reaction kinetics was first order with respect to thiol and zero order with respect to Mn oxides. A transient intermediate sulfur surface species observed during the reaction provides evidence for a mechanism involving two successive one-electron transfer steps. The reaction kinetics of fresh and aged δ-MnO 2 was investigated with cysteine and compared to that of manganite, a Mn(III) oxyhydroxide phase. The reactivity of aged δ-MnO 2 decreased as a result of structural transformation to cryptomelane but remained higher than that of manganite, suggesting the potential roles of transient Mn(III) surface intermediate in promoting the reduction of Mn(IV) in δ-MnO 2 and cryptomelane (compared to Mn(III) in manganite). This study demonstrates the importance of correlating Mn oxide mineral structure and redox reactivity and extends the potential for thiols commonly found in sedimentary environments to be utilized as electron shuttles during dissimilatory Mn reduction.

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Section: Resultscontrasting

confidence: 56%

“…Although the kinetics of Fe oxide reduction by different thiols has been extensively studied, , investigations of the reaction of thiols with solid Mn oxides have been limited and require analytical techniques that are capable of probing the fast reaction kinetics and related structural changes during the reaction. − …”

Section: Introductionmentioning

confidence: 99%

Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Eitel

Zhao

Tang

et al. 2018

Environ. Sci. Technol.

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“…Mn and Fe oxides are closely related regarding their chemical properties and often occur together in natural environments . Similar to Mn oxides, Fe oxides are susceptible to reduction by reduced sulfur. , Although the oxidizing capacities of Fe oxides are lower than those of Mn oxides, the abundance of Fe oxides in the environment is considerably higher. Therefore, Fe oxides might hinder the reactions of Cd-loaded Mn oxides with reduced sulfur.…”

Section: Resultsmentioning

confidence: 99%

“…S 2– , primarily derived from the activity of sulfate-reducing bacteria, and thiols, formed as a result of assimilatory SO 4 2– reduction or organic matter sulfurization, are two common reduced sulfur species found in natural waters. − They participate in the reduction process of Mn oxides, either abiotically or biotically, a common scenario in the redox-clines of lake water columns and stratified marine systems. ,, High concentrations of Mn oxides are usual above the oxic–anoxic (O 2 /H 2 S) interface in the aquatic environment, , where Mn oxides are reduced to Mn(II/III) species by H 2 S. − Thiols commonly function as excellent electron shuttles for the dissimilatory reduction of Fe and Mn oxides . The reaction between Mn oxides and thiols would convert thiols to their disulfide product and accordingly generate Mn(II/III) species .…”

Section: Introductionmentioning

confidence: 99%

Role of Reduced Sulfur in the Transformation of Cd(II) Immobilized by δ-MnO₂

Sun

Cui

et al. 2020

Environ. Sci. Technol.

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Mn oxides are the major sinks for Cd(II) in the aquatic environment. At the redox interface, reduced sulfur might affect the fate of sorbed Cd(II) by either reducing Mn oxides or forming strong complexes with Cd(II). Here, we investigated the fate of Cd(II) immobilized on δ-MnO 2 affected by reduced sulfur (S 2− and cysteine). A low concentration of S 2− led to Cd(II) migration from vacant sites to edge sites, while a high concentration of S 2− largely converted Cd(II) adsorbed on the surface of δ-MnO 2 to CdS. At low pH, the cysteine addition led to the release of Cd(II) initially adsorbed at the δ-MnO 2 vacant sites into the solution and caused the migration of a small portion of Cd(II) to the δ-MnO 2 edge sites. At high pH, a high concentration of cysteine led to the detachment of Cd(II) from δ-MnO 2 , Cd(II) readsorption by Mn(III)-bearing minerals, and Cd−cysteine formation. Changes of Cd(II) speciation were caused by δ-MnO 2 dissolution induced by reduced sulfur, the competition of generated Mn(II/III) for the adsorption sites, and the precipitation of Cd(II) with reduced sulfur. This study indicates that reduced sulfur is a critical factor controlling the fate of Cd(II) immobilized on Mn oxides in the aquatic environment.

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“…In this preliminary work, the 3-MPA is used as a representative of LMW reduced organosulfur compounds that can be usually found in natural aqueous environment, as detected by chromatographic methods [60][61][62]. Thus, we do not intend to declare exactly the presence of 3-MPA in the studied samples, but the presence of similar RSS organic compounds should be considered with regard to the electrochemical response.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical Evidence of non-Volatile Reduced Sulfur Species in Water-Soluble Fraction of Fine Marine Aerosols

Kušan¹,

Frka

Ciglenečki³

2019

Atmosphere

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The traditional voltammetric method at the mercury electrode, and an acidification step developed for the determination of reduced sulfur species (RSS) in natural waters, was for the first time used for the quantification of RSS in the water-soluble fraction of fine marine aerosols collected at the Middle Adriatic location (Rogoznica Lake). The evidence of two types of non-volatile RSS that have different interaction with the Hg electrode was confirmed: mercapto-type which complexes Hg as RS–Hg and sulfide/S0-like compounds which deposits HgS. The analytical protocol that was used for RSS determination in aerosol samples is based on separate voltammetric studies of a methyl 3-mercaptopropionate (3-MPA) as a representative of mercapto-type compounds and sulfide as a representative of inorganic RSS. Our preliminary study indicates the presence of mainly RS–Hg compounds in spring samples, ranging from 2.60–15.40 ng m−3, while both, the mercapto-type (0.48–2.23 ng m−3) and sulfide and/or S0-like compounds (0.02–0.26 ng m−3) were detected in early autumn samples. More expressed and defined RS–Hg peaks recorded in the spring potentially indicate their association with biological activity in the area. Those samples were also characterized by a higher water-soluble organic carbon content and a more abundant surface-active fraction, pointing to enhanced solubility and stabilization of RSS in the aqueous atmospheric phase.

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Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

Cited by 16 publications

References 55 publications

Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Role of Reduced Sulfur in the Transformation of Cd(II) Immobilized by δ-MnO₂

Electrochemical Evidence of non-Volatile Reduced Sulfur Species in Water-Soluble Fraction of Fine Marine Aerosols

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Mechanistic investigation of Fe(III) oxide reduction by low molecular weight organic sulfur species

Cited by 16 publications

References 55 publications

Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Effect of Manganese Oxide Aging and Structure Transformation on the Kinetics of Thiol Oxidation

Role of Reduced Sulfur in the Transformation of Cd(II) Immobilized by δ-MnO2

Electrochemical Evidence of non-Volatile Reduced Sulfur Species in Water-Soluble Fraction of Fine Marine Aerosols

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Role of Reduced Sulfur in the Transformation of Cd(II) Immobilized by δ-MnO₂