Department of Environmental Engineering, Peking University, The Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing, China.
Chemosphere. 2010 Feb;78(9):1093-9. doi: 10.1016/j.chemosphere.2009.12.036. Epub 2010 Jan 12.
In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes.
为了研究硝基取代基对硼掺杂金刚石（BDD）阳极上酚类降解的影响，我们研究了三种硝基苯酚异构体（2-硝基苯酚（2NP）、3-硝基苯酚（3NP）和 4-硝基苯酚（4NP））的循环伏安法，并将其在碱性条件下的整体电解结果与苯酚（Ph）进行了比较。伏安法研究表明，硝基苯酚可被羟基自由基攻击，硝基基团从芳环中释放出来。整体电解结果表明，所有酚类的降解都符合准一级反应动力学，降解顺序为：2NP>4NP>3NP>Ph。分子结构，特别是碳原子电荷，显著影响这些异构体的电化学氧化。在电解过程中分析了中间产物，主要为儿茶酚、间苯二酚、对苯二酚和羧酸，如乙酸和草酸。提出了一个简单的降解途径。此外，还观察到研究中酚类的降解速率与哈米特常数之间存在线性增加关系，这表明这些酚类的电化学氧化主要是由羟基自由基在 BDD 阳极上的亲电攻击引发的。
