Estudo do efeito sinérgico de antioxidantes comerciais no biodiesel

Abstract

Antioxidants are substances that play a fundamental role in protecting various materials against the adverse effects of oxidation, such as biocombustibles. The application of antioxidants in biocombustibles is widely done through the use of petroleum-derived compounds due to their low cost and high solubility in the matrix. However, the combined use of different antioxidants, both synthetic and natural, becomes interesting as it allows combining the best properties of each class, resulting in more satisfactory effects than the individual application of these components. Therefore, it is necessary to study the synergistic effects of these different classes of antioxidants to promote advancements in the application of antioxidant additives in biocombustibles. Thus, the aim of this study was to investigate the synergistic effect of three antioxidants (hydroquinone, quercetin, and vanillic acid) in a biodiesel matrix containing TBHQ, in order to understand the positive and negative interactions between these substances at the sample's induction point. The biodiesel used in the study was synthesized from soybean oil. To analyze the oxidative stability of the biodiesel, a prior aditivation of the biodiesel with the chosen antioxidants was necessary for this study. Tests were carried out with the intention of evaluating the individual performance of each antioxidant. The analyzes were conducted using the Rancimat and PetroXY methods. To investigate the oxidative stability and synergistic effect of the combination of antioxidants in the biodiesel, a factorial design was previously performed. This approach was used to optimize the results. The results demonstrated the synergistic effect between the species, especially for the combination of TBHQ and quercetin, whose performance in oxidative stability increased significantly, with an average induction point of 26.8 hours. The evaluations of oxidative stability showed the importance of combining antioxidants, as this strategy was able to potentiate the antioxidant action, providing greater protection against biodiesel oxidation. From the data of this research, new approaches can be developed, aiming to improve the oxidative stability and quality of the biocombustible over time.