Degradação de pesticidas presentes em água por processos de oxidação avançada

Abstract

2,4-Dichlorophenacacetic acid (2,4-D) is a selective herbicide with application in weed control, whereas glyphosate herbicide is classified as non-selective, systemic and post-emergent, and are commonly found in effluents 2,4-D is considered a pollutant of high toxicity and with moderate persistence in the environment, while glyphosate is considered a pollutant oflow toxicity to those who handle it and to the environment. The objective of this work was to study the removal of 2,4-D and glyphosate from the synthetic efluente using the advanced oxidative processes (POAS) H2O2/UV, Fenton, photo-Fenton, as well as UV light (photolysis) and adsorption activated charcoal. The Fenton process-based oxidation was catalyzed by ferrous (Fe2+), ferric (Fe3+) and copper (CuO) ions in acid médium, the hydrogen peroxide (H2O2) was used as the oxidizing agente. Photooxidation was performed by combining the Fenton process with ultravioleta (UV) radiation. The results of the experiments in the H2O2/UV and adsorption process showed better results on the removal of the 2,4-D herbicide when compared to the others, with the glyphosate herbicide the best results were with the photo-Fenton process made with the oxide of copper at pH 5 reaching 94.7% removal in 180 minutes at the concentration of 200 mg L-1 of H2O2. In the experiments with the herbicide glyphosate in the absence of light and in the photo-Fenton process with ferrous ions there was no degradation of the herbicide.