常压/低压湿空气催化氧化氯乙酸降解机理

Catalytic oxidation and degradation mechanism of chloroacetic acid by wet air under normal pressure/low pressure

利用无机熔盐水合物的温升效应,考察了氯乙酸废水在常压/低压下湿空气催化氧化降解效果,分别探讨了催化剂种类、反应温度、反应时间对氯乙酸和COD(化学需氧量)去除率的影响,并对反应机理进行了初步探讨。结果表明,在CaCl_(2)·2H_(2)O熔盐水合物中CuCl_(2)对氯乙酸的降解效果最佳,在200℃和0.35MPa条件下氯乙酸去除率可达97.2%,COD去除率可达90.7%。通过自由基抑制实验和中间产物分析推测反应机理为:在羟基自由基的协同催化下,氯乙酸依次降解为羟基乙酸、二羟基乙酸、甲酸、CO_(2)和水。

The catalytic oxidation and degradation of chloroacetic acid(CAA)wastewater in wet air under normal pressure/low pressure were investigated using the temperature rise effect of inorganic molten salt hydrate.The effects of catalyst type,reaction temperature and reaction time on the removal rates of CAA and COD(chemical oxygen demand)were investigated,and the reaction mechanism was discussed.It was found that CuCl_(2) had the highest catalytic performance for CAA in Ca Cl_(2)·2 H_(2)O molten salt hydrate medium among the tested catalysts.The removal rate of CAA and COD could reach 97.2% and 90.7% under the conditions of 200℃ and 0.35 MPa.The free radical inhibition experiments and intermediate products analysis revealed that CAA degraded into hydroxyacetic acid,dihydroxyphenylacetic acid,formic acid,CO_(2) and water in turns under the synergistic catalysis of hydroxyl free radicals.