Optimization of biodiesel production in a hydrodynamic cavitation reactor using used frying oil

Abstract

The present work demonstrates the application of a hydrodynamic cavitation reactor for the synthesis of biodiesel with used frying oil as a feedstock. The synthesis involved the transesterification of used frying oil (UFO) with methanol in the presence of potassium hydroxide as a catalyst. The effect of geometry and upstream pressure of a cavitating orifice plate on the rate of transesterification reaction has been studied. It is observed that the micro level turbulence created by hydrodynamic cavitation somewhat overcomes the mass transfer limitations for triphasic transesterification reaction. The significant effects of upstream pressure on the rate of formation of methyl esters have been seen. It has been observed that flow geometry of orifice plate plays a crucial role in process intensification. With an optimized plate geometry of 2mm hole diameter and 25holes, more than 95% of triglycerides have been converted to methyl esters in 10min of reaction time with cavitational yield of 1.28×10−3 (Grams of methyl esters produced per Joule of energy supplied). The potential of UFO to produce good quality methyl esters has been demonstrated.