title: Cation effects on the layer structure of biogenic Mn-oxides.
abstract: Biologically catalyzed Mn(II) oxidation produces biogenic Mn-oxides (BioMnO(x)) and may serve as one of the major formation pathways for layered Mn-oxides in soils and sediments. The structure of Mn octahedral layers in layered Mn-oxides controls its metal sequestration properties, photochemistry, oxidizing ability, and topotactic transformation to tunneled structures. This study investigates the impacts of cations (H(+), Ni(II), Na(+), and Ca(2+)) during biotic Mn(II) oxidation on the structure of Mn octahedral layers of BioMnO(x) using solution chemistry and synchrotron X-ray techniques. Results demonstrate that Mn octahedral layer symmetry and composition are sensitive to previous cations during BioMnO(x) formation. Specifically, H(+) and Ni(II) enhance vacant site formation, whereas Na(+) and Ca(2+) favor formation of Mn(III) and its ordered distribution in Mn octahedral layers. This study emphasizes the importance of the abiotic reaction between Mn(II) and BioMnO(x) and dependence of the crystal structure of BioMnO(x) on solution chemistry.
authors.affiliation: Department of Plant and Soil Sciences, Delaware Environmental Institute, University of Delaware, 152 Townsend Hall, Newark, Delaware 19716, USA. mzhu@udel.edu
authors.forename: Mengqiang
authors.initials: M
authors.lastname: Zhu
authors.forename: Matthew
authors.initials: M
authors.lastname: Ginder-Vogel
authors.forename: Sanjai J
authors.initials: SJ
authors.lastname: Parikh
authors.forename: Xiong-Han
authors.initials: XH
authors.lastname: Feng
authors.forename: Donald L
authors.initials: DL
authors.lastname: Sparks
mesh_terms: D001673:Biodegradation, Environmental; D002412:Cations / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017895:Manganese Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D016958:Pseudomonas putida / Q000378:metabolism*; D012965:Sodium Chloride / Q000737:chemistry; D013329:Structure-Activity Relationship; D017356:Synchrotrons; D056928:X-Ray Absorption Spectroscopy; D014961:X-Ray Diffraction
chemical_list: D002412:Cations; D017895:Manganese Compounds; D010087:Oxides; D012965:Sodium Chloride; C027424:manganese oxide