Environmental Science Research Institute, Huazhong University of Science and Technology, Wuhan 430074, PR China.
J Hazard Mater. 2013 Jan 15;244-245:295-302. doi: 10.1016/j.jhazmat.2012.11.038. Epub 2012 Nov 29.
The electrochemical degradation of p-nitrophenol (PNP) at boron-doped diamond (BDD) and platinum (Pt) anodes was studied by varying the parameters such as Cl(-) concentration, pH of aqueous medium and applied current density. The results obtained were explained in terms of in situ concomitant generation of hydroxyl radicals and chloride based oxidant species. The degradation of PNP was highly promoted in low concentration of NaCl electrolyte (less than 0.10 M), on contrary, the mineralization efficiency was poor at both BDD and Pt anodes with the NaCl concentration up to 0.20 M, which was ascribed to the formation of refractory chlorinated organic compounds. A maximum of 100% and 70% of COD removal was achieved in 5h of electrolysis period using both BDD and Pt anodes under similar experimental conditions. Kinetic study indicated that the degradation of PNP at BDD and Pt anodes followed pseudo-first-order reactions, and the reaction rate constant (k(s)) of the former was observed to be higher than that of the latter. Besides COD, conversion of PNP into various intermediate compounds and their degradations were also monitored. The mechanisms for PNP degradation at BDD and Pt anodes were proposed separately by considering the nature of respective intermediate species and their concentrations.
采用改变 Cl(-)浓度、水相介质 pH 值和施加电流密度等参数的方法，研究了在掺硼金刚石（BDD）和铂（Pt）阳极上电催化降解对硝基苯酚（PNP）的情况。根据原位同时生成的羟基自由基和基于氯的氧化剂物种，对所得到的结果进行了解释。在低浓度 NaCl 电解质（小于 0.10 M）中，PNP 的降解得到了极大的促进，而在 BDD 和 Pt 阳极上，NaCl 浓度高达 0.20 M 时，矿化效率很差，这归因于难处理的含氯有机化合物的形成。在类似的实验条件下，使用 BDD 和 Pt 阳极在 5 小时的电解周期内，COD 的去除率最高分别达到 100%和 70%。动力学研究表明，PNP 在 BDD 和 Pt 阳极上的降解遵循假一级反应，并且前者的反应速率常数（k(s)）高于后者。除 COD 外，还监测了 PNP 转化为各种中间化合物及其降解的情况。通过考虑各自中间物种的性质及其浓度，分别提出了 PNP 在 BDD 和 Pt 阳极上的降解机制。
