Degradação do herbicida diuron pelo processo oxidativoavançado de UV-C/NaOCl

Abstract

Environmental contamination by herbicides is a matter of concern due to their impact on ecosystems and high toxicity to humans. Diuron is a widely used herbicide that exhibits persistence in the environment and can reach water bodies, requiring effective methods for its degradation. Among the alternatives, advanced oxidation processes (AOPs) have been widely studied for the degradation of organic compounds. In this study, the degradation of Diuron by the UV-C/NaOCl advanced oxidation process was evaluated, using central composite design to optimize the experimental conditions. The effects of NaOCl concentration and pH on process efficiency were investigated. The best results were obtained at pH 7 and a concentration of 80 mg·L⁻¹, achieving 100% degradation in 90 minutes. Although the statistical analysis did not identify significant effects at the 10% level, a quadratic influence of pH was observed. Isolated photolysis resulted in 69.95% degradation, demonstrating the photosensitivity of Diuron. The initial reaction rates varied according to experimental conditions, with the highest rate observed at pH 4.17 (1.95 mg·L⁻¹·min⁻¹), probably due to greater generation of oxidizing species.The combination of UV-C and NaOCl proved to be promising for Diuron degradation. However, it is recommended to investigate the byproducts formed and to carry out tests using UV-B radiation (290–320 nm) under alkaline conditions, in order to take advantage of the high availability and molar absorptivity of the OCl⁻ ion in this wavelength range and pH condition, which may result in greater process efficiency.