Ferrita de cobalto reciclada de baterias de íon-Li exauridas e de rejeitos da mineração de ferro: síntese, caracterização e suas aplicações

• Autor(a) principal: Almeida, Jenifer Rigo
• Data de Publicação: 2023
• 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/10/17058
• topic: Química; Química ambiental; Reciclagem de lixo eletrônico; Compostos de ferro; Corantes; Catálise heterogênea; Análise eletroquímica; subject.br-rjbn

The objective of this work is to develop solutions for two possible environmental impacts associated with spent Li-ion batteries (LiBs) and reject from iron ore tailing (IOT) from the Mariana environmental accident (Minas Gerais, Brazil). The chemical characterization of starting materials (waste from active cathode material and reject) by inductively coupled plasma optical emission spectrometry (ICP OES) and flame atomic absorption spectrometry (FAAS) showed a recyclable potential of 45.22 ± 0.22 % (w/w) cobalt in LiB and 14.9 ± 1.5 % (w/w) iron in the raw reject from mining. Cobalt ferrites (CoFe2O4−recycled) were produced from recycled Co and Fe by the sol-gel method, which was characterized by X-ray diffraction (XRD). The average crystallite size determined by the Scherrer Equation was 54.4 nm. Scanning electron microscopy (SEM) analysis showed the formation of almost homogeneous large crystalline agglomerates. Energy-dispersive spectroscopy (EDS) performed elemental mapping and showed a mass percentage of 5.65 ± 0.18% (w/w) Co and 13.46 ± 0.38% (w/w) Fe. Co ferrites were applied as catalysts in heterogeneous photo Fenton-type reactions using solar radiation for methylene blue (MB) dye discoloration and as an electrochemical sensor for ascorbic acid. For solar photoFenton heterogeneous reactions, 20.0 mg of catalyst, 0.03 mol.L-1 H2O2, and 50.0 mL of 30.0 mg.L-1 MB dye solution at pH 3.0 were used under solar radiation. CoFe2O4−recycled proved to be an efficient catalyst for methylene blue dye discoloration, with a discoloration efficiency of 95.04 % in just 75 minutes. The pseudo-first-order reaction kinetics were adjusted with a velocity constant of 4.0560 10-2 min -1 and a correlation coefficient of 0.9909. The final disposal solution after catalysis was appropriate for disposal regarding the evaluated inorganic parameters. Since the elements of Al, Co, and Li pose no risks and iron remained below the limit of quantification, Mn, Ni, and Zn, which are regulated elements, were not detected in the final solution. The use of solar radiation during the experimental procedure promoted energy savings. CoFe2O4−recycled presented excellent electrochemical performance. Its use as an electrochemical sensor with a modified working electrode showed an anodic peak at 0.509 V for the oxidation of ascorbic acid (AA) to dehydroascorbic acid, showing an excellent linear correlation between the AA concentration and the current, with a coefficient of 0.9987. This recycled material demonstrated efficiency in two different applications: in the remediation of environmental problems, such as the disposal of textile effluents, and in the use as an electrochemical sensor.