Vegetable tannins-based additive as antioxidant for biodiesel

Abstract The development of more sustainable antioxidants alternatives for the improvement of biodiesel oxidation stability is gaining importance. Vegetable tannins are known for their antioxidant properties. In this work, acacia (Acacia mearnsii), chestnut (Castanea sativa) and quebracho (Schinopsis lorentzii) tannins extracts were used in mixture with triethanolamine as antioxidants for soybean biodiesel. Tannins were characterized by Folin-Ciocalteau method for the determination of total phenolic content (TPC) and against DPPH (1,1-diphenyl-2-picryl-hydracyl) radical for scavenging capacity. When applied to the biodiesel at a concentration of 350 mg L−1 in mixture with 1.59 %wt of triethanolamine, tannins were highly effective in enhancing oxidative stability with superior performance than synthetic antioxidant tert-Butylhydroquinone (TBHQ). These findings indicate that vegetal tannins can be used as a renewable alternative to enhance biodiesel oxidation stability.