Synthesis of Biodiesel from Waste Cooking Oil by One-step Esterification and Its Structural Characterization

The preparation of biodiesel as an alternative to petroleum-based fuels can expand the research and development of renewable energy, and is conducive to environmental protection. In this study, waste cooking oil (WCO) was used as raw material, and then pretreated, and then esterified with methanol under the action of sodium hydroxide catalyst to transformed into fatty acid methyl ester (FAME) to prepare biodiesel. The reaction conditions were optimized by a three factorial Box-Behnken design through response surface methodology, when the reaction temperature was 70.1 °C, the catalyst concentration was 1.013% and the molar ratio of methanol to oil was 6.5:1, the maximum FAME was up to 99.342%. Finally, the conversion of the triglyceride to the methyl ester was confirmed by NMR (1H and 13C), and no unsaturation was present in the methyl ester. The chemical composition of biodiesel was determined by GC-MS analysis. There are mainly 11 FAME ranging from C16 to C24. The potential of WCO to prepare biodiesel was obtained.