常低压湿空气催化氧化氯乙酸降解机理

Catalytic Wet Air Oxidation Degradation Mechanism of Chloroacetic Acid under Low Pressure

摘要:

利用无机熔盐水合物的温升效应，研究了氯乙酸废水在常低压下湿空气催化氧化降解效果，分别考察了催化剂种类、反应温度、反应时间对氯乙酸和COD去除率的影响，并对反应机理进行了初步探讨。研究表明，在CaCl2·2H2O熔盐水合物中CuCl2对氯乙酸的降解效果最佳，温和压力条件下氯乙酸去除率可达95%，COD去除率可达90%。自由基抑制实验和中间产物分析发现，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、CO2和水。

Abstract:

Taking advantage of the temperature-increasing effect of inorganic molten salt hydrates, catalytic wet air oxidation of chloroacetic acid (CAA) wastewater under low pressures was conducted. The effects of catalyst type, reaction temperature and reaction time on the removal of CAA and COD were investigated. It was found that CuCl2 has the highest catalytic performance in dihydrate of CaCl2 among the tested catalysts. The removal rates of CAA and COD can reach up to 95% and 90% respectively. The free radical inhibition experiments and intermediate products analysis revealed that the catalytic oxidation mechanism is that CAA degrades to glycolic acid, formic acid and finally to CO2 and water in turns under the synergistic catalysis of hydroxyl free radicals that is generated by the interaction of oxygen with the catalyst cycle of Cu(Ⅱ)-Cu(Ⅰ)-Cu(Ⅱ).