Fenton试剂降解除草剂溴嘧草醚的反应动力学研究

Kinetics study on degradation of herbicide ZJ0777 by Fenton reagent

探讨了Fenton试剂对超高效除草剂溴嘧草醚（ ZJ0777）的降解反应。考察了溴嘧草醚、过氧化氢、硫酸亚铁的初始浓度和反应温度等因素对溴嘧草醚降解反应的影响，建立了Fenton试剂降解溴嘧草醚的动力学方程。结果表明：在溴嘧草醚初始浓度分别为0.12和0.24 mmol/L时，达到其降解率90％以上所需的时间分别为32和48 h，而在溴嘧草醚为0.48 mmol/L时，反应84 h只有87％的溴嘧草醚降解；过氧化氢初始浓度在150~300 mmol/L范围内，浓度增加有利于降解反应进行；溴嘧草醚降解反应随亚铁离子浓度的增加而加快（5~20 mmol/L ），但过高的亚铁离子浓度对降解反应无效。温度在25~45℃范围内，反应的表观活化能Ea为75.34 kJ/mol。溴嘧草醚的氧化降解符合假一级反应动力学模型。

To establish an efficient oxidation process for ZJ0777 degradation, the effects of operating parameters such as initial concentrations of ZJ0777, H2 O2 and FeSO4？？7H2 O were examined during treatment with Fenton reagent. Firstly, the effect of initial ZJ0777 concentration was tested between 0. 12 mmol/L and 0. 48 mmol/L. More than 90% of ZJ0777 was degraded after 32 h with an initial concentration of 0. 12 mmol/L and in 48 h with an initial concentration of 0. 24 mmol/L. At an initial concentration of 0. 48 mmol/L, only 87% conversion of ZJ0777 could be obtained in 84 h. And the influence of initial amount of H2 O2 between 150 and 300 mmol/L was analyzed. The effective degradation of ZJ0777 was reached. The degradation rate was found to increase with increasing dosages of H2 O2 . Further, the effect of initial FeSO4？？7H2 O concentrations on the homogeneous degradation of＆nbsp;ZJ0777 was also investigated. The increase of Fe2＋ doses accelerated the degradation of ZJ0777 in the range of 5 -20 mmol/L. Addition of Fe2＋ became inefficient and unnecessary. Kinetic analysis indicated that ZJ0777 degradation by the homogeneous Fenton reaction could be described by a pseudo-first-order reaction model and the apparent activation energy was 75. 34 kJ/mol.