不同电催化工艺下苯酚的降解特性

Characteristic of Phenol Degradation Under Various Electrocatalysis Processes

比较了苯酚在电催化阳极氧化(AE)、阴阳两极协同降解(ACE)及亚铁离子存在下阴阳两极协同催化降解(FeACE)3种工艺下的降解及产物变化。在电流0.25 A下处理2 h,废水中COD的去除率在AE下仅30％,在ACE下为60％,而在FeACE下高达90％。苯酚降解的中间产物主要为对苯二酚、邻苯二酚、间苯二酚、对苯醌、顺丁烯二酸、反丁烯二酸和草酸等。在FeACE工艺下,中间产物还有甲酸.最终产物为CO_2。FeACE不仅提高了COD的去除速率,而且还有助于有毒中间产物的迅速消除,并使有机物彻底氧化,因而在环境保护中更具有应用前景。采用水杨酸作捕获剂证实了3种电催化工艺降解有机物的羟基自由基作用机理,其进攻苯环的活性顺序为:对位>邻位>间位,根据产物变化提出了苯酚降解路径。

Phenol degradation with three electrocatalysis processes; anodic electrocatalysis(AE), anodic-cathodic electrocatalysis (ACE) and ferrous ion catalyzed anodic-cathodic electrocatlysis (FeACE) were compared. At current of 0. 25 A, the removal rate of COD in wastewater is only 30% by using AE, while it is 60% by using ACE, and 90% by using FeACE. The main intermediates during the phenol degradation are hydroquinone, catechol, resorcinol, benzoquinone, maleic acid, fumaric acid and oxalic acid. When FeACE was used, formic acid was also observed and the final product is carbon dioxide. FeACE can increase the removal rate of COD, and benefit the rapid elimination of toxic intermediates as well. Furthermore , the process could reach the mineralization of organic compound, showing much more optimistic potential for the environmental protection. The mechanism of organic degradation was confirmed to be the role of hydroxyl radical by using salicylic acid as the radical trapping, which are more likely to attack benzene ring in the sequence of p-, m-, o-. A degradation mechanism for phenol was also proposed.