Atividade antioxidante de bio-óleo de esterco em mistura de ésteres metílicos de ácidos graxos produzidos a partir de óleo de soja

• Ano de defesa: 2022
• Autor(a) principal: Hilário, Thales César Xavier
• Orientador(a): Wisniewski Júnior, Alberto
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Programa de Pós-Graduação: Pós-Graduação em Química
• Palavras-chave em Português: Química; Biodiesel; Antioxidantes; Oxidação; Fenóis; Bio-óleo; Compostos; Fenólicos; Estabilidade oxidativa
• Palavras-chave em Inglês: Antioxidant; Accelerated oxidation; Bio-oil; Phenolic; Compounds
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://ri.ufs.br/jspui/handle/Ir01405a/15678

Biodiesel is a biofuel composed of a mixture of different fatty acid esters, derived from a certain raw material. Esters with unsaturated carbon chains are susceptible to oxidation, due to the formation and stabilization of radicals in the allylic position, generating oxidation products such as peroxides and hydroperoxides. Biodiesel prepared from soybean oil is main composed by unsaturated fatty acid esters, such as linoleic acid (C18:2) and oleic acid (C18:1). In this work, we evaluated the antioxidant potential of cattle manure bio-oil against a mixture of fatty acid esters produced from soybean oil (FAMES). Initially, a concentrated additive was prepared with bio-oil+FAMES (BOE) and it was characterized using FT-Orbitrap MS. For the evaluation of the antioxidant potential, experiments of accelerated oxidation were carried out with raw FAMES, FAMES with industrial antioxidant (butylated hydroxytoluene-BHT) and FAMES with the additive BOE. The concentrations of the additives used were based on the equivalent phenol contents determined by the Folin-Ciocalteau method, where a concentration ratio of 1000 µg g−1 of BHT to 5700 µg g−1 of BOE additive was obtained. The antioxidant capacity test (DPPH) revealed that the concentration equivalent to 1000 µg g −1 of BHT is only obtained using 6568 µg g −1 of BOE additive. The monitoring of oxidation was carried out through the content of esters by GC-FID. This content was used to evaluate the consumption of C18:2 and C18:1 esters during the oxidation test. The BOE additive showed inhibition of intermediate oxidation between BHT and FAMES control in the first 6 h of oxidation, being ineffective after this time. The monitoring of oxidation products was performed by FT-Orbitrap-MS, where it was possible to identify compounds resulting from the primary and secondary oxidation of the C18:2 and C18:1 esters in the oxidized samples.