Protection of apricot Biodiesel from Thermal Degradation by using natural antioxidants of Fagopyrum tataricum (L.) Gaertn

Abstract

The present study aims to improve the oxidation stability of wild apricot kernel oil biodiesel (WAKOB) by using natural antioxidants of Tartary buckwheat (Fagopyrum tataricum (L.) Gaertn). Biodiesel was synthesized at different catalyst (NaOH) concentrations, reaction temperatures, reaction time intervals and methanol-to-oil molar ratios. Thermal oxidative stability measurements were carried out according to EN14112 using a Rancimet instrument. Our results showed a high yield of biodiesel (97±1.092) at 65oC in the presence of 1% NaOH (%w/w oil) and methanol/oil molar ratio of 9:1 and for the time duration of 60 min. Proton nuclear magnetic resonance (1H NMR) confirmed the conversion percentage of kernel oil into biodiesel, which was further evidenced by Fourier transform infrared spectroscopy (FT-IR) and refractometer analyses. Methanolic fraction of Tartary buckwheat leaves (MTBWLF) was standardized to contain the highest amount of phenolics (209 mg gallic acid/100 g). In this study, the mixture of synthetic antioxidant butylated hydroxyl toluene (BHT) (0.25%) and methanolic extract of Tartary buckwheat leaves (0.5%) ensured high oxidation stability of biodiesel samples, leading to stabilizing factor of 4.86.