活性炭电催化氧化技术降解废水中氯苯机理研究

Study on Degradation of Chlorobenzene in Wastewater by Activated Carbon Electro-catalytic Oxidation Technology

采用活性炭电催化氧化技术,研究氯苯降解机理。配制质量浓度100 mg/L的氯苯水溶液,在活性炭电催化反应器槽电流1.0 A,降解时间为10～120 min条件下,采用高效液相色谱仪和气-质联用仪定性分析氯苯降解产物,研究氯苯降解过程;控制降解时间30min,在槽电流分别为0.5,1.0,2.0A条件下,分析水样中强氧化剂.OH含量。研究结果表明,不同的时间,废水中氯苯降解生成的中间产物不同,中间产物主要有对氯苯酚、对苯二酚、对苯醌、丁烯二酸和草酸等;氯苯废水在电催化作用下,产生具有强氧化能力的·OH,其降解过程为:·OH先攻击苯环Cl基团的对位,在亲电加成作用下生成对氯苯酚,Cl基团再被·OH取代生成对苯二酚和对苯醌,接着被氧化开环形成有机酸类物质,最终被矿化为CO_2和H_2O,但有机酸矿化的过程比较缓慢。

The aim was to discuss the degradation mechanism of chlorobenzene by activated carbon electro-catalytic oxidation technology. The study prepared the water solution of 100 mg/L chlorobenzene, and used high performance liquid chromatography and gas chromatography-mass spectrometry to qualitatively analyze chlorobenzene degradation products, in the activated carbon electro-catalytic reactor, with 1.0 A current and 10 - 120 min degradation time, and analyze the content of the hydroxyl radicals in the sample of water, with 0.5, 1.0, 2.0 A and 30 min degradation time. Results showed that the intermediate products of degradation in wastewater were diverse in different time, mainly including chlorophenol, hydroquinone, benzoquinone, maleic-acid and oxalic-acid. Under the electro-catalytic action, hydroxyl radicals were formed in the chlorobenzene-containing wastewater. During the degradation process, hydroxyl radicals attacked the para-position of Cl groups on the benzene ring, and then 4-Chlorophenol was formed under the electrophilic addition. After that, Cl groups were substituted by hydroxyl radicals, and formed hydroquinone and benzoquinone, then formed organic substances, finally formed carbon dioxide and water. The mineralization of organic acids was a slow process.