title: Formation of iron (hydr)oxides during the abiotic oxidation of Fe(II) in the presence of arsenate.
abstract: Abiotic oxidation of Fe(II) is a common pathway in the formation of Fe (hydr)oxides under natural conditions, however, little is known regarding the presence of arsenate on this process. In hence, the effect of arsenate on the precipitation of Fe (hydr)oxides during the oxidation of Fe(II) is investigated. Formation of arsenic-containing Fe (hydr)oxides is constrained by pH and molar ratios of As:Fe during the oxidation Fe(II). At pH 6.0, arsenate inhibits the formation of lepidocrocite and goethite, while favors the formation of ferric arsenate with the increasing As:Fe ratio. At pH 7.0, arsenate promotes the formation of hollow-structured Fe (hydr)oxides containing arsenate, as the As:Fe ratio reaches 0.07. Arsenate effectively inhibits the formation of magnetite at pH 8.0 even at As:Fe ratio of 0.01, while favors the formation of lepidocrocite and green rust, which can be latterly degenerated and replaced by ferric arsenate with the increasing As:Fe ratio. This study indicates that arsenate and low pH value favor the slow growth of dense-structured Fe (hydr)oxides like spherical ferric arsenate. With the rapid oxidation rate of Fe(II) at high pH, ferric (hydr)oxides prefer to precipitate in the formation of loose-structured Fe (hydr)oxides like lepidocrocite and green rust.
authors: School of Chemical Engineering and Technology, Tianjin University, Tianjin, PR China.
authors: Jia
authors: J
authors: Song
authors: School of Chemical Engineering and Technology, Tianjin University, Tianjin, PR China.
authors: Shao-Yi
authors: SY
authors: Jia
authors: School of Chemical Engineering and Technology, Tianjin University, Tianjin, PR China.
authors: Bo
authors: B
authors: Yu
authors: School of Chemical Engineering and Technology, Tianjin University, Tianjin, PR China.
authors: Song-Hai
authors: SH
authors: Wu
authors: School of Environmental Science and Engineering, Tianjin University, Tianjin, PR China; China Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Tianjin, PR China. Electronic address: xuhan@tju.edu.cn.
authors: Xu
authors: X
authors: Han
mesh_terms: D001149:Arsenates / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D001149:Arsenates; D006878:Hydroxides; D010087:Oxides; D007501:Iron; C025657:arsenic acid
keywords: Abiotic oxidation; Arsenate; Ferrous; Iron (hydr)oxides