The effect of BHA on oxidative stability of biodiesel from different sources

Abstract

The use of biodiesel is important, as it is a more sustainable energy source, obtained in many cases from vegetable oils and wastes such as fried used oils. In that way, there are plenty of advantages derived from its use, such as higher flash and combustion points. On the other hand, the oxidative stability of these samples is shorter, not complying with the European standards. That is the reason why the use of antioxidants, such as butylated hydroxyanisole (BHA), is vital to comply with the standards and make biodiesel marketable. The aim of this research work was to study the effect of BHA at different concentrations (up to 2000 ppm, depending on the kind of sample) on several biodiesel samples derived from several vegetable oils (rapeseed, seed and fried used oils). The results obtained pointed out the improvement of the induction point for all the samples as BHA concentration increased. Moreover, there was an influence of the raw material composition (concerning fatty acid profile) on the induction point of the biodiesel obtained and the subsequent optimum concentration of BHA. Thus, the fatty acid profile was different depending on the sample, being important the higher amount of methyl linoleate of seed and fried used biodiesel, which implied shorter induction points in these samples. As a consequence, for the latter, higher amounts of BHA (around 1400 ppm) were needed. As a conclusion, all the samples studied showed suitable oxidative stability values (over 8 hours) with the use of BHA (at variable optimum concentrations).