Projeto de reator fotocatalítico e produção de catalisador à base de cobalto recuperado de baterias íon-lítio exauridas: aplicação na degradação de corante têxtil

Abstract

In the present work, the objective was to recover cobalt from exhausted lithium-ion batteries for application in the degradation of reactive blue 5G dye and the design of a solar photocatalytic reactor. The cathodic material taken from cell phone batteries and the catalyst produced were characterized by the techniques TXRF, FTIR, Raman, DRX, MEV and N2 Physisorption, indicating the formation of a compound based on cobalt oxide. The produced catalyst (Co-Ox) was applied in the photocatalysis process for the degradation of the reactive blue 5G dye. The photocatalysis tests were conducted in a batch reactor with UV light, where the potential for degradation of the Co-Ox catalyst was evaluated. An experimental DCCR 22 planning was employed to evaluate the operational conditions of catalyst dosage and adsorption time that maximize the degradation of the dye. The kinetic tests of photocatalysis, photolysis and catalysis were performed under the best conditions indicated by the experimental planning, with an adsorption time of 19 min and catalyst dosage of 1.53 g L-1 for the degradation of 200 mL of a reactive blue 5G dye solution, with pH 2,0 and initial concentration of 100 mg L-1. Dye degradation was determined from the concentration evaluated by absorbance readings on a UV-Vis spectrophotometer (614 nm) in the range of 0 to 240 min of reaction. An evaluation of the influence of pH on the dye degradation rate was also carried out. For this, the Co-Ox catalyst was used and the pH values used in the tests were: 2,0, 2,5 and 3,0. It was found that the acid medium (pH 2,0) is the condition that most favors the hotocatalysis process in the degradation of the reactive blue 5G dye. To describe the experimental data of the catalysis and photocatalysis, the Langmuir-Hinshelwood model was suggested, which presented a good fit to the experimental data, indicating kinetic constant values of 0.042 ± 0.008 min-1 and 0.065 ± 0.008 min-1 for the catalysis and photocatalysis processes, respectively. The solar photocatalytic reactor showed a good performance in the degradation of the reactive blue 5G dye. With this, this study highlights the application of a material from the recycling of a solid waste containing toxic materials and attributes it to the possibility of use in industrial liquid effluent treatment processes.