Glycerol esterification of free fatty acids catalyzed by zinc glycerolate for biodiesel production from acidified palm oil: Optimization, kinetic study, and process evaluation

Abstract Biodiesel is an important alternative renewable liquid fuel due to its eco‐friendly, non‐toxic, and lower emissions. In this work, glycerol esterification catalyzed by zinc glycerolate was employed as a pretreatment to prepare biodiesel from acidified palm oil. The effects of stirring rate, catalyst amount, glycerol to free fatty acids (FFAs) molar ratio, and reaction temperature on the conversion of FFAs and concentration of monoglycerides, diglycerides, and triglycerides were investigated and optimized. The results show that the conversion of FFAs could reach 99.16% under the optimized conditions. Moreover, the kinetics of glycerol esterification catalyzed by zinc glycerolate at 160–200°C was obtained. Additionally, a comprehensive evaluation of the new biodiesel production process was also conducted. As a result, higher biodiesel content in the crude biodiesel phase was obtained after transesterification and separation using this new process. Overall, the study contributes to the utilization of waste oils to produce renewable energy and to minimize the waste management problem.