催化湿式氧化法处理吡虫啉农药废水的优化工艺条件

Catalytic wet air oxidation for treatment of pesticide wastewater from imidacloprid production

采用催化湿式氧化技术在2L高压反应釜中处理吡虫啉农药废水，分别以复合金属氧化物Cu／Mn、Cu／Ce、Ce／Mn及Ce／Ag为催化剂来考察对废水COD去除率的影响。发现Cu／Ce、Ce／Mn、Cu／Mn催化剂有较高的催化活性；Ce／Mn催化剂最稳定；Ce／Ag催化剂的Ag溶出量很大。选用性能良好的Ce／Mn催化剂，考察了反应温度、反应压力和废水的初始pH对催化湿式氧化效果的影响。结果表明，催化剂的加入可使COD去除率提高37％左右，同时处理后废水的BOD5／COD从0．19提高到0．65以上；当反应温度为150～230℃时，处理效率随温度升高明显增加；总压4．8MPa、氧分压1．2～2．4MPa时，适当增加氧分压亦能提高氧化效率；废水初始pH对氧化效果影响不大，但对催化剂的稳定性有影响。优化工艺条件最终为：催化剂为Ce／Mm温度190℃；氧分压1．6MPa；进水pH为6.211反应时间120min。

Many catalytic wet air oxidation（CWAO） runs were performed in a 2 L autoclave. Four bi-metal catalysts （Cu/Mn, Cu/Ce, Ce/Mn and Ce/Ag） were prepared and compared in the treatment of a pesticide wastewater from imidacloprid production. Ce/Mn was selected for the CWAO treatability study because of its high activity and low metal release, which increased as pH became more acidic. The CWAO treatment was conducted under a wide variety of temperature （150-210℃）, oxygen partial pressure （1.2-2.4 MPa）, and pH （3.52-11.54）. COD reduction, while not pH sensitive, increased with increasing temperature and oxygen partial pressure. The optimal CWAO conditions for treating the imidacloprid wastewater were identified. Using the Ce/Mn catalyst, the CWAO treatment, at 190 ℃ for 120 min under 1.6 MPa of oxygen partial pressure and a neutral pH, achieved 93% in COD reduction and increased BOD5/COD ratio from 0.19 to more than 0.65.