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Influence of the extracts of senna leaves, blackberries and hibiscus flowers in the oxidation reaction of commercial biodiesel

Romagnoli, Érica Signori, Borsato, Dionísio, Silva, Lívia Ramazzoti Chanan, Tashima, Daniele Lumi Mateus, Canesin, Edmilson Antônio
Biofuels 2020 v.11 no.7 pp. 839-845
Hibiscus, antioxidants, assays, biodiesel, blackberries, design, equations, flower extracts, flowers, free radicals, leaf extracts, leaves, oxidation, petroleum, phenolic compounds, raw materials, temperature, testing
Biodiesel is being increasingly used as an alternative energy source to reduce the dependence on derived petroleum fuels. However, sources of raw material for its production may contain substances susceptible to oxidation that are incorporated into biodiesel. As an alternative to minimize and even inhibit the oxidation reaction, antioxidant extracts from senna leaves, blackberries and hibiscus flowers were added to biodiesel, which present in their composition (structures) phenolic compounds capable of inhibiting the formation of free radicals in the reaction medium. The efficiency of the extracts was evaluated by the induction period determined using the Rancimat® method at temperatures of 110, 115, 120 and 125°C. The best results were obtained in the tests with large proportions of hibiscus flower extract. The mixture design provides predictive equations for all temperatures. Furthermore, in all the assays the values of the induction period were higher than in the control sample, thus demonstrating that the extracts of leaves of senna, blackberries and hibiscus flowers were efficient in protecting the biodiesel against the oxidation reaction. The multiresponse optimization proposed an optimal mixture containing 80% hibiscus flower and 20% senna leaves extract.