Facilitated ultrasonic irradiation in the degradation of diazinon insecticide

In this study, the degradation of diazinon insecticide was investigated using ultrasound facilitated by Fenton's and Fenton-like reagents under various experimental conditions. The effects of oxidant (persulphate ions, S2O82− and hydrogen peroxide (H2O2)), transition metal (including Co2+, Ag+ and Fe2+), Fenton's reagent concentration and temperature on diazinon degradation were examined. A solution with an initial diazinon concentration of 50 mg L−1 was used in this study. Ultrasonic irradiation in combination with Fenton's and Fenton-like reagents not only effectively degraded diazinon but also rapidly reduced its toxicity. The optimal experimental conditions were determined as follows: 20 mg L−1 Fe2+, 150 mg L−1 H2O2, 25 °C and pH 3. After reacting for 60 min, the diazinon removal efficiency reached 98%, with a mineralization efficiency of 30%. Degradation occurred primarily via oxidation and resulted in the substitution of sulphur with oxygen in the diazinon PS bond.