Degradação de Tartrazina via processo letro-fenton: uma proposta de prática experimental para o ensino investigativo de química no ensino médio

Abstract

Research in education proven to be applicable to teaching practice constitutes an important area of ​​study, as it plays a crucial role in updating and improving teaching methodologies. Therefore, this study presents the potential of investigative experimentation as a methodology for the construction of scientific knowledge. Thus, this work aims to develop, reflect on, and present a proposal for an investigative experimental activity for teaching chemistry in high school, based on the decontamination of water containing the yellow dye Tartrazine using the electro-Fenton process, and to evaluate the effectiveness of the treatment regarding residual toxicity. To this end, the Fenton process and the phytotoxicity test were adapted using low-cost materials, thus ensuring reproducibility in the classroom. In this study, the germination rate of lettuce seeds was evaluated in samples of treated, untreated, and control water. Based on the results, the removal of the dye color from the sample at a macroscopic level was attempted. However, the tests revealed significant levels of toxicity, demonstrating that the elimination of the color was not sufficient to reduce it. This result suggests that the toxicity of azo dyes, such as tartrazine, does not necessarily reside in the original molecule, but rather in products of its handling. The main considerations indicate the importance of combining different methods for the removal of these byproducts. Furthermore, it was found that the proposed experimental activity is replicable in schools, even without a laboratory, due to the low cost of the materials and reagents used.