UV-light-induced photocatalytic degradation of organic pesticides in agricultural soils with Fe2O3 and H2O2

Abstract

Organic pesticides pose significant concerns as primary sources of soil contamination in agricultural areas, and their potential to bioaccumulate in humans through the consumption of contaminated crops adds to the urgency of addressing this issue. This study looks at 18 different types of pesticides found in natural soil samples from farming areas. The pesticides are divided into four groups: organochlorines (OCP), organophosphorus (OPP), carbamates (Carb), and pyrethroids (Pyrth). The study investigates how the five most common pesticides (Atrazine, Chlorpyrifos methyl, Dimethoate, Heptachlor, and Methomyl) degrade when exposed to UV radiation at a wavelength of 306 nm, with or without 0.5 % Fe₂O₃ and 0.5 % H₂O₂ photocatalysts. The results demonstrate complete photolysis of all pesticides over irradiation periods ranging from 26 to 96 h under UV radiation. It is notable that by incorporating Fe₂O₃ and H₂O₂, the degradation of pesticides was enhanced significantly compared to photolysis alone, achieving complete photocatalytic degradation within 8–11 h of irradiation. It is worth mentioning that Fe₂O₃ + H₂O₂ exhibits superior photocatalytic efficiency compared to Fe₂O₃. Furthermore, the highly toxic and persistent organochlorine heptachlor was successfully degraded in soil within 5 h using the Fe₂O₃ + H₂O₂ photocatalyst. The research provides a comprehensive understanding of the intricate mechanisms underlying the photocatalytic deterioration of these pesticides. This study offers valuable insights for designing effective UV-light-driven photocatalysts for environmental remediation.