几种难生化芳香化合物的电催化降解研究——结构对降解活性的影响

Study on electrocatalytic degradation of biorefractory aromatic compounds: Effect of structure on degradation reactivity

研究了环境治理中难生化降解的典型芳香污染物苯胺、氯苯、对氯酚和对硝基酚的电催化降解.实验发现,在3h内这些化合物能完全去除,COD去除40%以上,电化学氧化指数在16%～43%.有机物和COD的去除符合表观一级反应动力学.其去除速率大小为:苯胺>氯苯>对氯酚>对硝基酚.苯环上取代基对有机物电催化降解活性有很大的影响,从易到难为:氨基>氯>硝基;苯环上羟基的加入降低了电催化活性.通过Hammett常数定性描述了上述结构与电催化性能的关系.证实了有机物的电催化降解主要基于羟基自由基与有机物的亲电反应机理.

This study on the electrocatalytic degradation of four typical aromatic compounds, aniline, chlorobenzene, pchlorophenol and pnitrophenol, showed that within 3 h the aromatic compounds could be completely removed; and that the COD removal rate could be more than 40%. During degradation, the electrochemical oxidation index (EOI) were in range from 16% to 43%. The removal of aromatic compounds and COD were found to follow well an apparent firstorder kinetic reaction; and were in the order aniline>chlorobenzene>pchlorophenol>pnitrophenol. The ring substituents influenced the electrocatalytic reactivity of the aromatic compounds significantly in sequence: group of NH2, Cl and NO2. The addition of the hydroxyl group on the benzene ring would lead to the decrease of electrocatalytic reactivity. The relationship between structure and electrocatalytic reactivity was interrupted by Hammett constant. The mechanism of aromatic compounds electrocatalytic degradation was verified mainly by the electrophilic addition reaction between hydroxyl radicals and organic compounds.