Intensification of biodiesel synthesis from waste cooking oil (Palm Olein) in a Hydrodynamic Cavitation Reactor: Effect of operating parameters on methyl ester conversion

Abstract

ABSTRACT This paper investigates a new route for intensification of methyl ester synthesis in Malaysia via alkali-catalysed transesterification of waste cooking oil derived from palm olein using a hydrodynamic cavitation reactor. The effects of the oil to methanol molar ratio (1:4–1:7), catalyst loading concentration (0.5–1.25 wt%) and reaction temperature (50–65 °C) have been investigated using an optimised plate with 21 holes of 1 mm diameter and an inlet pressure of 2 bar in a 50 L of hydrodynamic cavitation reactor assisted by a double diaphragm pump. Optimal conversion of 98.1% was achieved in 15 min in a hydrodynamic cavitation reactor with 1:6 molar ratio of oil to methanol, 1 wt% of catalyst and 60 °C of reaction temperature. It has been observed that a significant reduction in the optimum reaction time (about 6 fold) for transesterification from 90 min for mechanical stirring approach to 15 min for the hydrodynamic cavitation approach. Optimal yield efficiency of 12.50 × 10 −4 g/J was found using hydrodynamic cavitation and it was 8 fold higher than 1.5 × 10 −4 g/J when mechanical stirring was used.