Study of Photochemical and Sonochemical Processes Efficiency for Degradation of Acibenzolar-S-Methyl Fungicide in Aqueous Solution

In this study, the catalytic performance of photo-Fenton and sono-Fenton processes were tested on Acibenzolar-S-methyl fungicide. UV light source and ultrasound irradiation source (20 kHz of the frequency with a maximum of 125 W power output) were used for Fenton-based processes. The sono-Fenton process revealed the higher efficiency in ASM degradation with a 100% degradation rate within 20 min compared to photo-Fenton, Fenton, photolysis, and sonolysis processes that achieved only 90%, 52%, 43% and 19%, respectively. The investigation shows that ultrasound irradiation has accelerated the efficiency of the Fenton process by increasing the hydroxyl radicals ∙OH generation. The kinetic study was carried out under different pH conditions, ferrous ions concentration and hydrogen peroxide dosages. The result showed that the optimum condition for acibenzolar-s-methyl degradation was the acidic medium, low concentration of hydrogen peroxide and low concentration of ferrous ions. The contaminant was monitored and analysed in duplicate with high-performance liquid chromatography. A transformation mechanism pathway of the sonochemical oxidation was suggested based on gas chromatography/mass spectra analysis.