Selective Decomposition of Aqueous Nitrate into Nitrogen Using Iron Deposited Bimetals
Selective Decomposition of Aqueous Nitrate into Nitrogen Using Iron Deposited Bimetals
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DOI：
10.1021/es802498k
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发表时间：
2009-04-01
影响因子：
11.4
通讯作者：
Lo, Shang Lien
中科院分区：
文献类型：
--
作者：
Liou, Ya Hsuan;Lin, Chin Jung;Lo, Shang Lien
在地下水中硝酸盐还原的情况下，问题是如何选择性地将硝酸盐[N(+V)]转化为无毒的氮素[N(0)]，而不是完全还原氨[N(-III)]。不幸的是，到目前为止报道的硝酸盐中近100%的总氮被裸露的零价铁(ZVI)还原为氨。在这项研究中，贵金属(铂、钯和金)和铜沉积在铁表面，为硝酸盐还原提供有利的途径，采用完全混合或连续自发氧化还原反应的方法。用X射线衍射仪、X射线光电子能谱、扫描电子显微镜/能谱和电化学分析对所制备的样品进行了表征。结合高真空系统的残气分析仪证实了硝酸盐还原生成N-2。实验结果表明，Pd和Cu的紧密沉积促进了吸附在铜表面的原子氢从NOx中吸走氧，促进了Pd表面N-2的生成。在含硝酸盐的碱性溶液中，使用0.3wt.%Pd-0.5wt%Cu/Fe时，N-2的最佳选择性与30%相近。对于地下水处理，铁沉积的钯和铜可以促进一种既不需要大量添加化学品也不需要复杂设备的工艺的开发。
In the case of the reduction of nitrate in groundwater, the problem is how to convert nitrate [N(+V)] selectively to nontoxic dinitrogen [N(0)] and not to completely reduced ammonia [N(-III)]. Unfortunately, near 100% of the total nitrogen in nitrate is reductively converted to ammonia using naked zerovalent iron (ZVI) thus far reported. In this study, deposition of noble metals (Pt, Pd, and Au) and Cu on iron surface to offer favorable pathways for nitrate reduction was fabricated using either the complete mixing or the successive method with spontaneous redox reactions. The prepared samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy/energy disperse X-ray spectroscopy, and electrochemical analysis. The formation of N-2 from the reduction of nitrate was confirmed by residual gas analyzer coupled to a high vacuum system. Based on the experimental results, the ZVI deposited Pd and Cu closely is suggested to promote the abstraction of oxygen from NOx by adsorbed atomic hydrogen on the Cu surface, and enhance N-2 formation on the Pd surface. An optimum N-2 selectivity of similar to 30% obtained in the alkaline solution containing nitrate using 0.3 wt.% Pd-0.5 wt% Cu/Fe is evident. For groundwater treatment, iron deposited Pd and Cu could facilitate the development of a process requiring neither a massive addition of chemicals nor complex equipment.