Biodiesel production from sunflower oil using a combined atmospheric cold plasma jet-hydrodynamic reactor

Abstract Conventional transesterification processes are time-consuming and costly. New methods, such as non-thermal plasma technology, reduce the reaction time and temperature. Therefore, this study aims to evaluate the use of a combined plasma jet–hydrodynamic reactor for transesterification. The plasma jet used in this research comprised a ceramic tube with a central high-voltage electrode and a ring outer electrode, into which argon gas was fed. The hydrodynamic reactor consisted of a rotor with holes in its environment that rotated in a fixed stator. In this study, the operating parameters for plasma jet evaluation include the molar ratio of methanol to oil (4:1, 6:1, 8:1), catalyst concentration (0.75, 1, 1.25 wt.%), and reaction time (30, 60, and 90 s). The operating parameters for evaluating the hydrodynamic reactor included reaction time (30, 60, and 90 s), reaction temperature (40, 50, and 60 °C), and rotor–stator distance (10, 20, and 30 mm). The response surface method (RSM) and Box–Behnken design were used to analyze and optimize the results. According to the results, using a plasma jet alone produces a conversion percentage of 83%. Finally, the product’s physical and chemical characteristics were evaluated, and it was found to be insufficiently compliant with international standards.