Fenton试剂降解除草剂溴嘧草醚的反应动力学研究

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。

Kinetics study on degradation of herbicide ZJ0777 by Fenton reagent

To establish an efficient oxidation process for ZJ0777 degradation, the effects of operating parameters such as initial concentrations of ZJ0777, H₂O₂ and FeSO₄·7H₂O 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 H₂O₂ 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 H₂O₂. Further, the effect of initial FeSO₄·7H₂O concentrations on the homogeneous degradation of 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.