含乐果废水的循环电-Fenton氧化过程及其影响因素

为克服传统Fenton(Conventional Fenton,简称CF)法中存在着Fe2 在反应初始时即被氧化且反应过程中产生大量铁泥(Fe的复杂络合物)的不足,研究了循环电-Fenton(Circulating Electro Fenton,简称CEF-FeRe)法氧化降解自配乐果废水的过程及其各影响因子的作用机制.CEF-FeRe反应所需的H2O2通过蠕动泵缓慢加入到电解池中,而被氧化了的Fe2 又在阴极被还原,使得Fenton反应能持续进行.在乐果浓度为200mg·L-1时,通过多个单因素试验确定最佳CEF-FeRe反应条件为:常温、pH值为3.0、H2O2/Fe2 的摩尔比为10、H2O2的加入量为理论剂量、恒流0.5A.结果表明,在此条件下反应120min后COD去除率为81.67%,乐果在25min内去除率为99.4%.通过测定CEF-FeRe以及CF反应过程中Fe2 和H2O2的变化情况验证了CEF-FeRe反应的机理.动力学研究结果表明.乐果废水的CEF-FeRe反应符合一级动力学反应规律.CEF-FeRe法处理实际乐果废水也可以得到91.16%的乐果去除及68.53%的COD去除,这表明CEF-FeRe法处理乐果废水效率高且运行费用较低的特点.

Oxidation treatment of dimethoate-containing wastewater by a circulating electro fenton method

The main disadvantage of Conventional Fenton (CF) treatment is the lack of Fe2+ due to the rapid oxidation of Fe2+ to Fe3+.To solve this problem, a Circulating Electro-Fenton reactor (CEF-FeRe) was employed to degrade dimethoate, during which H2O2 was added to the electrolytic cell continuously by a peristaltic pump and Fe2+ could be regenerated to Fe3+ on the cathode. The operating conditions for this CEF-FeRe, such as pH value, electric current, Fenton reagent dosage, and the molar ratio of Fe2+ to H2O2, were optimized by individual factor experiments. The research results showed that the optimal conditions for dimethoate (200 mg·L-1) degradation are: pH=3.0, n(Fe2+)/n(H2O2)=0.1, electric current=0.5 A and Fenton's reagent dosage at its theoretical dosage. Under these conditions, COD removal rates reached 81.67% within 120 min, while 99.4% of dimethoate was degraded within 25 min. The mechanism of the CEF-FeRe reaction was investigated by monitoring the changes of H2O2 and Fe2+concentration during the process. Kinetics results revealed that dimethoate oxidation follows the pseudo-first-order kinetic model at different pH values. Treatment of actual dimethoate wastewater by the CEF-FeRe showed that the removal rates of dimethoate and COD were about 91.16% and 68.53%, respectively, which indicated that the CEF-FeRe could be a cost-efficient method for dimethoate degradation.