Aplicação de processo fenton-heterogêneo no tratamento de águas contaminandas por ácido 2, 4 – diclorofenoxiacético

Abstract

Brazil is today the largest consumer of pesticides in the world, and, as agricultural production advances, consumption has also advanced. The herbicides are used as a tool for effective management of weeds, among them 2,4-Dichlorophenoxyacetic acid (2,4-D). Among the various techniques used in the treatment of contaminated water and effluents has been highlighted the Advanced Oxidative Processes (POAs). Thus, the present study aimed to evaluate the performance of the Fenton-Heterogeneous process applied in the chemical degradation of the 2,4-D contaminant in synthetic contaminated water using iron oxide pellets and as the primary oxidizing agent hydrogen peroxide (H2O2). To evaluate the degradation of the contaminant, tests were performed to determine the amount of catalyst to be used in batch tests, after which tests were performed with variation of H2O2 concentration, as well as kinetic tests to follow the reaction time. The results were obtained through High Performance Liquid Chromatography (HPLC). The results of the catalyst mass study showed that it does not have a significant effect on the degradation of the 2,4-dichlorophenoxyacetic acid molecule. The pelitic iron oxide catalyst also had no adsorptive effect on the contaminant in the study range evaluated. In the experiments of Fenton-Heterogene using different concentrations of H2O2 (400, 600, 800 and 1000 mg/L) it was possible to observe that for all the tests contaminant degradation occurs practically instantaneously with high average rates of degradation at the beginning the process. In all the catalytic oxidation tests the contaminant was removed, the highest removal being obtained with a concentration of 1000 mg/L H2O2, reaching approximately 48% at the end of 4 minutes of reaction, with average degradation rate at the beginning of the reaction time of 3.34x104 mgL-1.min-1, reducing in the course of it. In this way it can be concluded that the Fenton-Heterogeneous process presents potential for the treatment of contaminated water and/or effluents containing pesticides.