Reductive Transformation of Birnessite by Aqueous Mn(II)
- 30 June 2011
- journal article
- research article
- Published by American Chemical Society (ACS) in Environmental Science & Technology
- Vol. 45 (15), 6366-6372
- https://doi.org/10.1021/es2013038
Abstract
Reaction of aqueous Mn(II) with hexagonal birnessite at pH 7.5 causes reductive transformation of birnessite into feitknechtite (β-Mn(III)OOH) and manganite (γ-Mn(III)OOH) through interfacial electron transfer from adsorbed Mn(II) to structural Mn(IV) atoms and arrangement of product Mn(III) into MnOOH, summarized by Mn(II) + Mn(IV)O(2) + 2 H(2)O → 2 Mn(III)OOH + 2 H(+). Feitknechtite is the initial transformation product, and subsequently converted into the more stable manganite polymorph during ongoing reaction with Mn(II). Feitknechtite production is observed at Mn(II) concentrations 2 orders of magnitude below thermodynamic thresholds, reflecting uncertainty in thermodynamic data of Mn-oxide minerals and/or specific interactions between Mn(II) and birnessite surface sites facilitating electron exchange. Under oxic conditions, feitknechtite formation through surface-catalyzed oxidation of Mn(II) by O(2) leads to additional Mn(II) removal from solution relative to anoxic systems. These results indicate that Mn(II) may be an important moderator of the reductive arm of Mn-oxide redox cycling, and suggest a controlling role of Mn(II) in regulating the solubility and speciation of phyllomanganate-reactive metal pollutants including Co, Ni, As, and Cr in geochemical environments.This publication has 34 references indexed in Scilit:
- Nanophase Transition Metal Oxides Show Large Thermodynamically Driven Shifts in Oxidation-Reduction EquilibriaScience, 2010
- Cation Effects on the Layer Structure of Biogenic Mn-OxidesEnvironmental Science & Technology, 2010
- Physiochemical controls on the crystal-chemistry of Ni in birnessite: Genetic implications for ferromanganese precipitatesGeochimica et Cosmochimica Acta, 2009
- Manganese Oxides: Parallels between Abiotic and Biotic StructuresJournal of the American Chemical Society, 2006
- Structural model for the biogenic Mn oxide produced by Pseudomonas putidaAmerican Mineralogist: Journal of Earth and Planetary Materials, 2006
- Reduction of Colloidal Manganese Dioxide by Manganese(II)Journal of Colloid and Interface Science, 2002
- Reactivity of Pb(II) at the Mn(III,IV) (Oxyhydr)Oxide−Water InterfaceEnvironmental Science & Technology, 2001
- Manganese mineral formation by bacterial spores of the marine Bacillus, strain SG-1: Evidence for the direct oxidation of Mn(II) to Mn(IV)Geochimica et Cosmochimica Acta, 1995
- Transformations of Synthetic Birnessite as Affected by pH and Manganese ConcentrationClays and Clay Minerals, 1994
- Mechanism of autoxidation of manganese in aqueous solutionEnvironmental Science & Technology, 1975