Study on the photocatalytic degradation of insecticide methomyl in water

Photo-Fenton degradation of the insecticide methomyl in water using Fe-ZSM-5 zeolite and AlFe-pillared montmorillonite catalysts under halogen lamp light was studied. The study was performed at room temperature in a glass batch reactor under constant airflow. Both catalysts exhibited activity in the wet oxidative degradation of methomyl. The rate of photodecomposition of methomyl was measured using UV spectrometry and HPLC, while its mineralization was followed using ion chromatography (IC) and total organic carbon (TOC) analyzer. IC results showed that mineralization led to formation of sulfate, nitrate and ammonium ions during the process. Under our conditions, complete disappearance of 16.22 mg/L of pure pesticide and 100% or 80% TOC removal occurred within 4 h using 5 g/L or 1 g/L of Fe-ZSM-5 zeolite, respectively. The Fe-ZSM-5 was found to be a better catalyst. Pseudo-first-order rate constants were calculated, and the performed treatments compared.