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Photochemical Formation and Transformation of Birnessite: Effects

  • [设施]:北京正负电子对撞机
  • [期刊/会议名称]:Environmental Science & Technology
  • [摘要]:As important components with excellent oxidation and adsorption activity in soils and sediments, manganese oxides affect the transportation and fate of nutrients and pollutants in natural environments. In this work, birnessite was formed by photocatalytic oxidation of Mn2+ aq in the presence of nitrate under solar irradiation. The effects of concentrations and species of interlayer cations (Na+, Mg2+, and K+) on birnessite crystal structure and micromorphology were investigated. The roles of adsorbed Mn2+ and pH in the transformation of the photosynthetic birnessite were further studied. The results indicated that Mn2+ aq was oxidized to birnessite by superoxide radicals (O2 •−) generated from the photolysis of NO3 − under UV irradiation. The particle size and thickness of birnessite decreased with increasing cation concentration. The birnessite showed a plate-like morphology in the presence of K+, while exhibited a rumpled sheet-like morphology when Na+ or Mg2+ was used. The different micromorphologies of birnessites could be ascribed to the position of cations in the interlayer. The adsorbed Mn2+ and high pH facilitated the reduction of birnessite to low-valence manganese oxides including hausmannite, feitknechtite, and manganite. This study suggests that interlayer cations and Mn2+ play essential roles in the photochemical formation and transformation of birnessite in aqueous environments.
  • [发表日期]:2018
  • [第一作者]:张腾飞
  • [第一作者单位]:华中农业大学
  • [通讯作者]:邱国红
  • [通讯作者单位]:华中农业大学
  • [论文类型]:0
  • [期刊分类]:SCI1区
  • [学科分类]:环境科学_ 生态学
  • [影响因子]:6.653
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