Reduction of Nitrate, Bromate, and Chlorate by Zero Valent Iron (Fe0)
Reduction of Nitrate, Bromate, and Chlorate by Zero Valent Iron (Fe0)
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DOI：
10.1061/(asce)0733-9372(2003)129:1(10
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发表时间：
2003
影响因子：
2.2
通讯作者：
P. Westerhoff
中科院分区：
文献类型：
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作者：
P. Westerhoff
氧阴离子存在于饮用水中，构成潜在的健康风险，应加以控制。在水处理过程中加入零价铁（Fe\u0）以去除氧阴离子是可能的。在接近中性pH值（~7）和好氧条件下，用Fe\u0电化学还原了所研究的3种氧阴离子(NO\d3（\u-）、BrO\d3（\u-）、ClO\d3（\u-）。质量平衡提供了强有力的证据，证明氨是硝酸盐还原的主要副产物，氯酸盐还原的氯化物，溴酸盐还原的溴化物。质子在反应过程中被消耗，导致pH值增加（即产生氢氧化物）。氧阴离子去除率依次下降：BrO\d3(\u-)>ClO\d3(\u-)>NO\d3（\u-）。间歇式和连续流柱试验中氧阴离子去除率的差异表明，较高的固液比增加了氧阴离子电化学还原，将间歇式动力学数据扩大到更大的规模必须考虑固液比。氧阴离子中氮、氯和溴元素的原子结构（原子半径、电子轨道构型、电子亲和力）以及这些元素与氧之间的键解离能是表征Fe\u0相对还原速率的良好指标。
Oxo-anions occur in drinking waters, pose potential health risks, and should be controlled. It may be possible to incorporate zero-valent iron (Fe\u0) into water treatment processes to remove oxo-anions. Under near neutral pH (~7) and aerobic conditions, the three oxo-anions studied (NO\d3(\u-), BrO\d3(\u-), ClO\d3(\u-)) were electrochemically reduced by Fe\u0 in batch and continuous-flow packed column experiments. Mass balances provided strong evidence that ammonia is the primary reduction by-product from nitrate, chloride from chlorate, and bromide from bromate. Protons were consumed during the reaction, resulting in an increase in pH (i.e., production of hydroxide). Oxo-anion removal rates decreased as follows: BrO\d3(\u-)>ClO\d3(\u-)>NO\d3(\u-). Differing rates of oxo-anion removal between batch and continuous flow column tests suggested that higher solid (Fe\u0) to liquid ratios increase oxo-anion electrochemical reduction, and scaling up of batch kinetic data to larger scale must consider the solid–liquid ratios. The atomic structure (atomic radii, electron orbital configuration, electron affinity) of nitrogen, chlorine, and bromine elements of the oxo-anions, and the bond dissociation energy between these elements and oxygen, were good indicators for the relative rates of reduction by Fe\u0.