Green tea (Camellia assamica) extract as an antioxidant additive to enhance the oxidation stability of biodiesel synthesized from waste cooking oil

Green tea (Camellia assamica) leaves extract as an antioxidant additive and its influence on the oxidation stability of biodiesel produced from waste cooking oil (WCO) has been studied. Camellia assamica extract can be used as an eco-friendly and non-toxic alternative of synthetic antioxidants used to enhance the oxidation stability of biodiesel. The extraction of antioxidants was performed in an oil bath at 60 degrees C for 4 h using ethanol as a solvent. Folin-Ciocalteu assay was used to determine the total phenolic content (TPC) of green tea extract spectrophotometrically. Calibration was done using Gallic acid at a concentration of 10-50 ppm in methanol. The calibration curve was used to obtain the concentration of phenolic compounds present in green tea extract. The extract yield was found to be 0.3 g g(-1) dry green tea leaves. The TPC in the extract was found to be 173.16 mg GAE g(-1) biomass. A 1000 ppm concentration of green tea extract in biodiesel was capable of enhancing the induction period (IP) of biodiesel from 2.88 h to 7.11 h, which met the American (ASTM D67451) and European (EN 14214) standard specification for oxidation stability of biodiesel. Hence, Camellia assamica can be used as a natural antioxidant for enhancing biodiesel stability in place of synthetic antioxidants derived from non-renewable resources.