Síntese e aplicação de fotocatalisadores núcleo-casca de FexOy@C na descoloração do índigo carmim em meio aquoso

• Ano de defesa: 2024
• Autor(a) principal: Panzembock, Marcos Vinicio Medeiros
• Outros Autores: [e-mail]
• Orientador(a): Henriques, Cristiane Assumpção
• Banca de defesa: Zotin, Fátima Maria Zanon , Silveira, Erika Batista , Costa, Lidia Oazem de Oliveira da
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso embargado
• Idioma: por
• Instituição de defesa: Universidade do Estado do Rio de Janeiro
• Programa de Pós-Graduação: Programa de Pós-Graduação em Engenharia Química
• Departamento: Centro de Tecnologia e Ciências::Instituto de Química
• País: Brasil
• Palavras-chave em Português: Fotocatálise; Catalisadores; Fe3O4@C; αFe2O3@C; Índigo carmim
• Palavras-chave em Inglês: Photocatalysis; Catalysis; Indigo carmine
• Área do conhecimento CNPq: ENGENHARIAS::ENGENHARIA QUIMICA::PROCESSOS INDUSTRIAIS DE ENGENHARIA QUIMICA
• Link de acesso: http://www.bdtd.uerj.br/handle/1/25963

The textile sector is one of the Brazilian economy’s most traditional and important segments, generating more than 1 million formal jobs and 8 million indirect jobs. In 2022, it represented more than 18% of the total number of workers allocated to industrial production, with the clothing sector being the second largest employer in the manufacturing industry. On the other hand, this sector is one of the biggest polluters, responsible for releasing about 54% of the waste generated by the entire industry into the environment. When released untreated into the aquatic environment, these wastes hinder the penetration of sunlight into the deepest layers of seas and rivers, reducing the solubility of oxygen in the water and causing worrying toxic effects on aquatic flora and fauna. Indigo carmine is one of the most widely used dyes in the industry, especially in the textile segment for coloring and dyeing garments. The increase in the application of this dye in the industry consequently generates the growth of effluent production. Core-shell nanostructures have been used in photocatalytic reactions and are considered promising due to their versatility, low cost and their differentiated physicochemical properties. In this work, nucleus-shell nanoparticles of FexOy@C were synthesized by hydrothermal process from two different methodologies for application in photocatalytic reactions in the discoloration of indigo carmine (IC). The X-ray diffraction analysis (XRD) identified the formation of Fe3O4@C and αFe2O3@C. In Fourier transform infrared spectroscopy (FTIR) bands around 1600 cm-1 and 1700 cm-1 appeared relative to the C=C and C=O bonds. This hypothesis was corroborated with the aid of Electron Scattering Spectroscopy (EDS). Magnetic analysis (VSM) showed that Fe3O4@C presents a superparamagnetic behavior, with saturation magnetization of 55 emug-1, while α Fe2O3@C presented practically zero magnetism. In the textural analysis, the specific areas were determined by N2 adsorption/desorption. The results showed values of 103 m² g-1 and 29 m² g-1 for Fe3O4@C and α Fe2O3@C, respectively. Whereas, for pure magnetite (Fe3O4) and hematite (αFe2O3), the values were less than 10 m² g-1. The performances of the nanoparticles were evaluated in the photocatalytic reactions for discoloration of the IC solution (20 mg L-1). The photolysis test with the presence of H2O2 (10%) showed that the solution presented total discoloration at the end of the process, while in the absence of this reagent the values were practically null. In the experiments, different catalyst masses were used, 5 mg, 10 mg and 20 mg. In the adsorption tests, with the highest mass tested, of 20 mg, the adsorption equilibrium was reached from 30 min with maximum discoloration of 85% for the Fe3O4@C and 80% for the α Fe2O3@C. In the Photo-Fenton tests, with a mass of 5mg, the Fe3O4@C achieved total discoloration in 60 min, while the α Fe2O3@C reached a maximum degree of discoloration of 85% in 120 min. In the Fenton reactions, with the same mass of 5 mg, both core-shell nanoparticles were able to completely discolor the dye in the times at the end of 120 min.