Process intensification in the refinery effluent treatment using a photocatalytic membrane reactor

• Ano de defesa: 2019
• Autor(a) principal: Caique Prado Machado de Oliveira
• Orientador(a): Míriam Cristina Santos Amaral
• Banca de defesa: Lucilaine Valéria de Souza Santos, Guilherme Oliveira Siqueira, Ana Cláudia Figueiras Pedreira de Cerqueira
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Minas Gerais
• Programa de Pós-Graduação: Programa de Pós-Graduação em Saneamento, Meio Ambiente e Recursos Hídricos
• Departamento: ENG - DEPARTAMENTO DE ENGENHARIA SANITÁRIA E AMBIENTAL
• País: Brasil
• Palavras-chave em Português: Titanium dioxide; Refinery effluent; Microwave synthesis; Recycled membrane; Photocatalytic membrane reactor; Recalcitrant compounds
• Link de acesso: http://hdl.handle.net/1843/30726

The first part of the present paper presents an environmentally friendly synthesis of TiO2 nanoparticles assisted by microwave from titanium tetrachloride and water with potential for oil refinery wastewater treatment. Anatase nanocrystalline particles with a mean crystallite size of 14 nm were obtained according to XRD, TEM and EELS characterization. The photocatalytic activity of the catalyst was tested first by degradation of the standard methylene blue molecule and 95% degradation was verified after 300 minutes of reaction. Kinetic tests with the dye indicated adjustment to first order kinetics. The UF permeate of a Membrane Bioreactor treating real refinery wastewater composed largely of biologically recalcitrant compounds was subjected to photodegradation in the presence of the catalyst synthesized under UV-C irradiation. The highest percentages of TOC and TN removal were 32% and 67%, respectively, under pH conditions equal to 10 and catalyst concentration of 100 mg L-1 in 90 minutes of reaction. For this condition, the Electric Energy per Order (EE0) calculated was 356.29 KWh m-3 order-1. The catalyst exhibited stability in photoactivity for 4 cycles. In the second part of the study, a hybrid system called Photocatalytic Membrane Reactor (PMR) was constructed and tested for treatment of the previously mentioned effluent. The PMR configuration was based on the use of the cleaner synthesized titanium dioxide catalyst and reverse osmosis membranes recycled by chemical oxidation with sodium hypochlorite. The system proved to be efficient in the removal of UF permeate recalcitrant compounds with values up to 60% of COD removal. It was verified that photocatalysis exerts the greatest impact on the removal of organic matter (21%) when compared to photolysis with UV light (15%) and membrane separation only (9%). The permeate fluxes of the recycled membrane remained practically constant in the tests with the presence of the catalyst in the PMR, showing that it reduces the fouling, also confirmed by the fouling resistance 7.3 times lower in the tests performed with the presence of the oxide. No evidence was detected that the catalyst damaged the membrane structure. In contrast, stabilities in fluxes and photocatalysis were verified by reuse tests. SEM analyzes of the membrane prior to permeation revealed a non-rough structure. Morphological changes were not observed on the membrane surface after permeations. However, TiO2 deposits were visualized and confirmed by EDS. Analysis of EDS in various fields of the PMR permeate did not identify the titanium element showing that the recycled membrane is able of retaining the catalyst. The compounds present in the effluent are mainly associated with microbial products such as SMPs and EPS that had their concentrations reduced based on the disappearance of the bands 3300 cm-1, 1620 cm-1 and 609 cm-1 of the infrared spectrum. The obtained data showed that the system is a promising technology for the removal of residual recalcitrant organic matter of the UF-MBR permeate before the polishing process of the petroleum refinery wastewater with a view to reuse.