Natural manganese oxide: Combined analytical approach for solid characterization and arsenic retention

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• 作者：Ouvrard ; S. ; de Donato ; Ph. ; Simonnot ; M.O. ; Begin ; S. ; Ghanbaja ; J. ; Alnot ; M. ; Duval ; Y.B. ; Lhote ; F. ; et. al.
• 刊名：Geochimica et Cosmochimica Acta
• 出版年：2005
• 期刊代码：27_00167037
• 类别：ear
• 出版时间：June 1, 2005
• 卷：69
• 期：11
• 页码：2715-2724
• 文件大小：610 K

摘要

To understand the retention of As on a natural manganese sand, the structural, textural and chemical properties of the solid were first investigated by combining scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron-energy-loss spectroscopy (EELS), X-ray diffraction (XRD), BET N₂ gas adsorption, diffuse reflectance Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. Manganese sand could be mainly described as a mixture of a phyllomanganate, lithiophorite [(Al,Li)MnO₂(OH)₂], and pyrolusite (MnO₂). Iron particle, kaolinite and gibbsite type-phases were also observed. Particles organization led to the presence of a mesoporosity with pore diameters ranging from 100 to 200 Å and a specific surface area of 23 m² g⁻¹. Contact with an As(V) solution (0.67 mmol L⁻¹) led to an average fractional surface coverage of 0.4. Both As (V) and (III) were present on the surface of the sand in a 1:1 ratio. As(V) was sorbed on lithiophorite-type particles through surface complexation type reaction. As(III) was thought to result from As(V) reduction mechanism on iron particles.