Produção de catalisador a partir das pilhas zinco-carbono exauridas e avaliação na degradação fotocatalítica do corante vermelho reativo 4B

Abstract

In the present work, the recovery of zinc from depleted zinc-carbon cells for application in the degradation of the reactive red dye 4B was studied. The synthesized catalyst (C-Zn) was also submitted to FTIR, MEV and DRX characterizations, to obtain information about the structure and morphology of the material. C-Zn was used as a catalyst in degradation tests of the reactive red dye 4B with an initial concentration of 100 mg L-1 using photolysis, catalysis and photocatalysis techniques. In order to verify the best operational conditions, kinetic degradation tests were carried out, changing the initial pH value of the solution, time for the adsorption step and dosage of the catalyst used. The indicated operating conditions were for pH 7, catalyst dosage of 1 g L-1 and time for adsorption step of 15 minutes. The photocatalysis process presented itself as the best degradation proposal, verifying approximately 80% degradation with 180 minutes of operation. Analyzing the degradation kinetics with the pseudo-first order mathematical model, an R2 value of up to 0.972 for pH 11 was found. Similar reaction speed was observed for pH values of 2, 3, 5, 7 and 9, reaching 0.012 min-1. For catalyst reuse tests, it was observed that there were no significant losses in the catalytic efficiency of C-Zn, allowing the use in more than one degradation cycle of the reactive red dye 4B. In a test carried out in batch using sunlight as a source of photoactivation of the ZnO catalyst, it was possible to observe a degradation rate higher than 60%. In this context, the work presented the potential for the recovery of metals from batteries, the use of reverse logistics and the possibility of applying recovered products in the treatment of effluents, preserving water resources and the ecosystem.