Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing, 210095, China; State Key Laboratory of Bioelectronics, Southeast University, Nanjing, 210096, China.
Department of Chemistry, College of Science, Nanjing Agricultural University, Nanjing, 210095, China.
J Hazard Mater. 2019 Jul 5;373:547-557. doi: 10.1016/j.jhazmat.2019.03.118. Epub 2019 Mar 28.
Using boron-doped diamond (BDD) to mineralize recalcitrant organics has been one of the hottest areas of research interest in the field of water treatment. Here we report for the first time that, in the presence of nitrite ions (NO), the anodic oxidation of phenol with BDD electrode will lead to the formation of nitrated by-products of phenol. These by-products include 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, 2,6-dinitrophenol, 2,4,6-trinitrophenol, 2,3,4,6-tetranitrophenol, 2,3,4,5,6-pentanitrophenol, as well as a large number of dimers and trimers of nitrophenols. Increasing the concentration of NO will not only greatly affects the degradation and mineralization of phenol, but also enhances the formation of nitrophenols. The nitrated by-products are mainly generated via electrophilic substitution reactions mediated by nitrogen dioxide radicals and hydroxyl radicals, as well as via coupling reactions of phenol. In addition, it is found that several simple nitrophenols may also be formed in nitrate media. As a whole, formation of nitrated by-products is a novel phenomenon in anodic oxidation processes. Since nitrated aromatics are well known for their persistence in the environment, their formations in BDD anode cells should be carefully scrutinized before such technology is applied to groundwater remediation.
使用掺硼金刚石（BDD）矿化难降解有机物是水处理领域最热门的研究领域之一。在这里，我们首次报道，在亚硝酸根离子（NO）存在的情况下，BDD 电极阳极氧化苯酚会导致苯酚的硝化副产物的形成。这些副产物包括 2-硝基苯酚、4-硝基苯酚、2,4-二硝基苯酚、2,6-二硝基苯酚、2,4,6-三硝基苯酚、2,3,4,6-四硝基苯酚、2,3,4,5,6-五硝基苯酚，以及大量的硝基苯酚二聚体和三聚体。增加 NO 的浓度不仅会极大地影响苯酚的降解和矿化，还会增强硝基苯酚的形成。硝化副产物主要通过二氧化氮自由基和羟基自由基介导的亲电取代反应以及苯酚的偶联反应生成。此外，还发现硝酸盐介质中也可能形成几种简单的硝基苯酚。总的来说，硝化副产物的形成是阳极氧化过程中的一种新现象。由于硝化芳烃在环境中具有很好的持久性，在将该技术应用于地下水修复之前，应该仔细审查 BDD 阳极电池中硝化副产物的形成。
