Banca de QUALIFICAÇÃO: ELLEN CRISTINA PEREIRA SANTOS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE: ELLEN CRISTINA PEREIRA SANTOS
DATA: 06/10/2025
HORA: 09:00
LOCAL: Auditório do Departamento de Química "Professor José Roberto de Oliveira Torres"
TÍTULO: Estudo da aplicação dos extratos de capim-limão, erva-cidreira, malva-do-reino e TBHQ como antioxidantes em biodiesel de soja
PALAVRAS-CHAVES: antioxidants; biodiesel; oxidative stability
PÁGINAS: 37
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Química
RESUMO:

Study of the application of lemongrass, lemon balm, mallow extracts and TBHQ as antioxidants in soybean biodiesel. Oxidative stability of biodiesel is a crucial factor for its commercial and environmental viability, as it directly influences its durability, performance, and safety during storage and use. In this context, there has been growing interest in natural alternatives to synthetic antioxidants, especially plant extracts rich in secondary metabolites such as flavonoids, tannins, and phenols. In this study, we present an investigation on the application of plant extracts and the synthetic antioxidant TBHQ in soybean biodiesel. The experiment was conducted at three concentrations (500 ppm, 1500ppm and 3000 ppm) at 110 °C using the Rancimat® accelerated oxidation technique. Among the extracts evaluated, the highest total phenolic content was observed in mallow extract (EMR) with 74.24 ± 1.9 mg EAG/g, followed by lemon balm extract (EEC) which presented 41.77 ± 2.8 mg EAG/g and lemongrass extract (ECL) with 25.93 ± 0.8 mg EAG/g. Regarding the antioxidant activity against the ABTS•+ radical, the same decreasing order was observed: EMR (991.62 ± 11.18 mM Trolox/g) > EEC (428.30 ± 27.0 mM Trolox/g) > ECL (414.01 ± 24.4 mM Trolox/g). Thermal analysis indicated that TBHQ and mallow extract were the most stable, followed by lemongrass extract and lemon balm extract. At a concentration of 3000 ppm, an increase in the induction period of 68.18%, 62.65%, and 50.0% was observed in comparison to the control sample for lemongrass, lemon balm, and mallow extracts, respectively. The antioxidants increased the induction period in the following decreasing order: TBHQ > lemongrass extract (LCE) > lemon balm extract (LCE) > mallow extract (MCE). However, only TBHQ extended the biodiesel induction period beyond 13 hours. The studies highlighted the importance of using plant extracts and synthetic antioxidants in controlling the oxidative degradation of soybean biodiesel, significantly increasing its stability.

MEMBROS DA BANCA:
Presidente - 2363808 - EDMILSON MIRANDA DE MOURA
Interno - 1998602 - EVERSON THIAGO SANTOS GERONCIO DA SILVA
Interno - 1614544 - JURANDY DO NASCIMENTO SILVA
Externo ao Programa - 1731422 - JOAO SAMMY NERY DE SOUZA