Óxidos Mistos (ZnO/Fe2O3/ZnFe2O4@SiO2) Reciclados a Partir de Baterias de Zn-MnO2 e Rejeitos de Mineração de Ferro Aplicados como Fotocatalisadores, Pseudocapacitores e Sensores Eletroquímicos

• Autor(a) principal: Magnago, Luma Barbosa
• Data de Publicação: 2024
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/17431
• topic: Área(s) do conhecimento do documento (Tabela CNPq); Baterias alcalinas; rejeitos de mineração de ferro; reciclagem; fotocatalisador; pseudocapacitor; sensor eletroquímico; subject.br-rjbn

In this study, mixed oxides were prepared using spent alkaline battery anodes, silt fraction (FS), and raw iron mining reject (RB), and applied as photocatalysts, pseudocapacitors, and electrochemical sensors. Characterization analyses revealed that the mixed oxides (FS) and (RB) are composed of SiO2, ZnO, Fe2O3, ZnFe2O4, and are formed by agglomerates of nanoscale particles with a diameter < 200 nm and cubic shapes. For the photocatalytic study, a complete 23 factorial design was conducted to determine the optimal conditions of pH, H2O2 quantity, and the mass of mixed oxide (FS) or (RB) required for the decolorization of 1.56 x 10-6 mol of methylene blue dye (AM) under solar irradiation. The maximum decolorization efficiency was 96 % after 30 min using mixed oxide (FS) and 90 % after 45 min using mixed oxide (RB) with 2.35 x 10-5 mol of H2O2 and 20 mg of the material at pH 3. The efficiencies remained unchanged even after four successive decolorization cycles, and no solution after treatment showed toxicity in the Allium cepa (onion seed) test. In electrochemical studies, mixed oxide (FS) exhibited favorable characteristics for pseudocapacitor application due to its high capacitance (87.16 F g -1 ), energy density (27.24 Wh kg-1 ), power density (524.41 W kg -1 ), and reversibility (93 %). On the other hand, mixed oxide (RB) showed better sensitivity for use as an ascorbic acid (AA) sensor, with a value of 0.23 A mol-1 L cm-2 . This study encompasses recycling of waste and rejects to prepare new materials with multifunctional applications, contributing to environmental sustainability, preservation of raw materials, and the generation of a circular economy.