Estudo do potencial do tratamento de corantes têxteis por catálise heterogênea utilizando catalisador ZnMn2O4 sintetizado de pilhas exauridas

Abstract

In the midst of technological advances, environmental waste management is a major global challenge. Batteries are an example of solid waste rich in metals that are discarded without reusing their components. Looking at it from another angle, in the class of liquid waste, effluents from the textile industry also have great polluting potential and need to be managed correctly. In view of this, the present work sought an alternative for managing both wastes, by studying the potential of treating effluents contaminated with the textile dyes reactive blue 5G and reactive red 4B through the action of the zinc manganite (ZnMn2O4) catalyst synthesized from waste zinc-carbon batteries. For this, in addition to the synthesis and characterization of the catalyst, preliminary tests were carried out to adjust the pH of the dyes solution studied, with the subsequent study of the conditions that maximize its degradation through an experimental design DCCR 22. In addition, the adjustment was carried out from mathematical models to catalysis kinetic data, catalyst reuse tests and the analysis of costs and yield of its production. The characterization analysis results indicated that the methodology applied in this study successfully synthesizes the compound ZnMn2O4. From kinetic tests, the potential of the treatment by catalysis was verified, being favored in an acid place. Analyzing the data obtained in the experimental design, the dependence of pH on the catalytic process was verified. The optimal point obtained by the experimental design resulted in a degradation percentage of approximately 94 % for the 5G reactive blue dye and 98% for the 4B reactive red dye from an initial concentration of 100 mg L-1. In the dye degradation kinetics analysis, both mathematical models evaluated, pseudo-first order and proposed by the Langmuir-Hinshelwood mechanism, obtained a good fit to the experimental data (R2 > 0.9). However, the second model presents the distinction of having a greater theoretical basis in relation to the catalysis steps. In addition, the synthesized material showed catalytic activity for 15 reaction cycles, decreasing its efficiency by less than 10%. In the economic analysis, the estimated production costs of the catalyst presented a low value, and the yield of its recovery evidenced the potential of this waste management methodology In summary, the link between the efficiency of the treatment of reactive blue 5G and reactive red 4B textile dyes by heterogeneous catalysis by the compound ZnMn2O4 and the feasibility of their synthesis from depleted zinc-carbon batteries, represents a promising strategy for the management of both waste in question.