Degradação do herbicida ácido 2,4-diclorofenoxiacético por fotocatálise heterogênea

Abstract

2,4-Dichlorophenoxyacetic acid (2,4-D) is one of the most widely used herbicides in Brazil and worldwide due to its low cost, strong solubility in water and effectiveness in controlling weeds. The presence of 2,4-D in aquatic environments causes damage to human and animal health. In this context, Advanced Oxidative Processes (AOPs) have been shown to be a viable alternative for removing such contaminants from water. Thus, this study evaluated the degradation of 2,4- D through the process of heterogeneous photocatalysis, using TiO2 as a semiconductor and UV radiation. The process was carried out in a chimney reactor with a capacity of approximately 1 litre. In addition, the phytotoxicity of 2,4-D was studied through bioassays with Lactuca sativa seeds. The influence of the variables pH, catalyst concentration and reaction time was analysed using the complete factorial experimental design23. The best result was obtained under the conditions of pH 5, TiO2 (0.5 g/L) for 40 minutes of reaction, resulting in a degradation percentage of 90.2 %. The experimental kinetic data showed that the experiment best fitted the pseudo-first order model. The seeds used in the phytotoxicity bioassays proved to be totally sensitive to the powder samples. Keywords: