Influence of antioxidants from pequi leaves on the thermal and oxidative stability of biodiesel

Abstract

In this study, the efficacy of antioxidants found in pequi leaves was examined for safeguarding pequi biodiesel (EBP) against oxidation. The results reveal notable achievements. The antioxidant activity of AFP (a pequi leaf antioxidant additive) was assessed at various concentrations, demonstrating that as the concentration of AFP increases, the inhibition percentage significantly rises, reaching a remarkable inhibition of 99.12% at 100 mg L⁻¹, with a calculated IC₅₀ of 25.4 mg L⁻¹. Additionally, the analysis of the AFP composition revealed the presence of terpenes and oxygenated compounds, which are well known for their antioxidant properties. Furthermore, the research emphasized the significance of thermogravimetric analysis in evaluating the thermal stability of additives, identifying critical temperatures at which AFP begins to protect biodiesel against oxidation (247.18°C) and the point at which its effectiveness may diminish (469.19°C). The EBP met quality standards regarding acidity, water content and density, but exhibited slightly lower oxidative stability compared with established standards. The correlation between the thermal degradation of biodiesel and the induction period highlighted the efficacy of AFP in mitigating thermal degradation. Nevertheless, it also indicated that maintaining biodiesel quality requires complementary approaches to minimize degradation over time.