Fe(II)介导的亚硝酸盐还原耦合砷氧化研究

Fe(II)-mediated nitrite reduction coupled with arsenic oxidation

中文关键词: 铁  砷  亚硝酸盐  氧化还原

英文关键词: iron  arsenic  nitrite  redox

中文摘要:

      地下水等还原环境中亚硝酸盐与铁的生物地球化学循环对砷的迁移转化行为有重要影响，然而，现有的研究对其反应过程及机理的认识仍非常缺乏。本研究以二价铁（Fe(II)）作为还原剂，研究了不同pH、亚硝酸盐浓度及Fe(II)浓度下，Fe(II)与亚硝酸盐的氧化还原反应对三价砷氧化及固液分配的影响。结果表明，在pH 为6.0-7.5范围内，砷氧化速率随着pH升高而加快；在Fe(II)为2-8 mmol/L浓度范围、NO2-为0.6-2 mmol/L浓度范围内，增加亚铁及亚硝酸盐的投加量均会加快反应速率。反应66小时内，在pH为7.0时砷氧化率达到91.96%，在pH为7.5时砷氧化率达到99.39%，已去除绝大部分砷，同时亚硝酸盐的去除率也达到73%以上。研究成果对地下水砷污染与亚硝酸盐同步去除具有重要借鉴意义。

英文摘要:

      Biogeochemical cycling of nitrite and iron in reducing environments, such as groundwater, has an important influence on the transport and transformation behaviour of arsenic, however, the understanding of the reaction processes and mechanisms in existing studies is still very lacking. In this study, the effect of the redox reaction between Fe(II) and nitrite on the oxidation and solid-liquid partitioning of trivalent arsenic was investigated at different pH, nitrite concentration and Fe(II) concentration using divalent iron (Fe(II)) as the reducing agent. The results showed that the arsenic oxidation rate was accelerated with the increase of pH in the range of 6.0-7.5, and the reaction rate was accelerated with the increase of Fe(II) in the range of 2-8 mmol/L and NO2- in the range of 0.6-2 mmol/L. The reaction rate was also accelerated with the increase of Fe(II) and nitrite dosage. Within 66 hours of reaction, the arsenic oxidation rate reached 91.96% at pH 7.0, and 99.39% at pH 7.5, removing most of the arsenic, while the removal rate of nitrite reached more than 73%. The research results have important reference significance for the synchronous removal of arsenic pollution and nitrite in groundwater.