Síntese da ferrita de cobre e sua aplicação na degradação fotoquímica do 2,4-D

Abstract

The increase in the consumption of pesticides, including herbicides, has been causing a series of discussions about its application and its consequences for humans and the environment. One of the most widely used herbicides in the world is 2,4- dichlorophenoxyacetic acid (2,4-D), however, its presence has been observed in water bodies, causing impacts on the health of animals and humans. As an alternative for the degradation of this contaminant, copper ferrite (CuFe2O4) synthesized by the coprecipitation method was used in this work. The samples were synthesized using the ratio 0.1 and 0.5 metal / base, employing two types of salts, one with the Fe2+ ion and the other with the Fe3+ ion. The catalysts were subjected to a thermogravimetric test and calcined at 600 °C. X-ray diffractograms were performed to determine the formation of the copper ferrite phase. The catalyst was studied in photodegradation reactions of the herbicide 2,4-D in aqueous solution, through heterogeneous photocatalysis with and without the addition of oxidizing agents. A preliminary photocatalytic test was carried out to choose the catalyst with the best performance, the best sample being 0.1_Fe3+Cu, with the oxidizing agent H2O2. The parameters of the photocatalytic experiments were studied, such as: pH, concentration of catalyst, concentration of herbicide, concentration of oxidizing agent. The catalyst degraded 100% of the herbicide in 60 min of reaction. With the experimental data, following the law of initial velocities, a law of velocity was created to represent the system model. The law of speed followed a Langmuir-Hinshelwood type kinetics and the reaction mechanism was studied, being possible to conclude that the catalyst completely degraded 2,4-D together with H2O2.