钛基RuO_x-PdO电极电催化氧化降解苯胺研究

Electro-catalytic Oxidative Degradation of Aniline with RuO_x-PdO/Ti Electrode

电化学氧化法是难降解有机物降解处理的1种有效方法,高效电极材料是该技术得以实现的关键,近年来,金属氧化物电极的研究倍受重视。作者制备了钛基RuOx-PdO电极,并以其为阳极进行了苯胺的电催化氧化降解研究。发现该电极对苯胺有较好的电催化氧化性能:在以NaCl(1g/L)为支持电解质、初始pH=5.0、电流密度=20mA?cm-2的条件下,对浓度为640mg/L的苯胺溶液电催化氧化降解1h,苯胺去除率可达99.4%,溶液COD(化学需氧量)去除率达84.0%,电极具有较长使用寿命。苯胺的去除主要是活性氯的间接氧化作用实现的,苯胺降解中间产物的去除则是活性氯间接氧化和电极直接氧化协同作用的结果。用GC-MS检测到苯胺电催化氧化过程中有对氯苯胺、2,4-二氯苯胺、2,4,5-三氯苯胺和苯醌等中间产物生成,据此探讨了苯胺的降解途径。

Electro-chemical oxidation is an effective method for organic compound degradation, the high-efficiency electrode is the key component to realize this technology. In the present paper, the titanium supported ruthenium-palladium binary oxides electrode was prepared by coat of the corresponding metal chlorides on titanium substrates and thermal decomposition. The electrode was used for the electro-catalytic oxidative degradation of aniline in aqueous solution. The bulk electro- lysis was performed under the constant current operation. It was observed that the removal rates of aniline and chemical oxygen demand(COD) were 99.4% and 84.0% respectively at the electrode after 1h electrolysis under the following conditions: NaCl=1g/L; pH=5; current density, 20mA·cm-2; initial aniline concentration 640mg/L. The final degradation product was found to be carbon dioxide. The electro-catalytic oxidation degradation activity of the RuOx-PdO/Ti electrode in terms of the removal rate of aniline and COD kept nearly constant until it was used for 100 times. The removal of aniline was found to be related intimately to indirect oxidation by active chlorine species, and the removal of COD could be attributed to the synergic effect of direct oxidation by electrolysis and indirect oxidation. The main intermediate species during the aniline degradation, such as p-chloroaniline, 2,4-dichloroaniline, 2,4,5-trichloroaniline and benzoquinone etc, were detected with GC-MS. A pathway of aniline degradation was proposed.