Análise da estabilidade oxidativa de biodiesel de soja com aditivos naturais antioxidantes.

Abstract

The soybean biodiesel is a fuel susceptible to oxidation due to its chemical composition. To reduce or inhibit this oxidation, synthetic antioxidants are added to the industrial production. In the present study, we propose as an alternative the use of natural antioxidants composed by Plinia cauliflora leaves and peels of Ipomoea batatas skin peel and purple pulp and Beauregard cultivar with ethyl, methyl and isopropyl alcohols in 500 and 1000 ppm concentrations. The extracts were characterized by the determination of total phenols by the Folin-Ciocalteau method, antioxidant activity by the free radical scavenging method DPPH• and accelerated oxidative stability of biodiesel with the addition of natural extracts. In relation to the content of total phenols, the extract with the greatest prominence was the methyl extract of Plínia cauliflora with 52,15 ± 1,64mgAGE, whereas the extract that showed greater inhibitory activity of the free radical DPPH• was the ethyl extract of barks of Ipomoea batatas cultivar Beauregard with 59,36 ± 1,70% and 8,23 ± 0,25mgAAEg-1. The best result regarding the oxidative stability of biodiesel in the presence of the natural antioxidant extract was that with Plínia cauliflora 1000 ppm iso-propyl alcohol, with 13,13 ± 0,28h of induction time, resulting above the stipulated by the current Brazilian resolution.