Evaluation of Biodiesel Production in a Hydrodynamic Cavitation Reactor from Waste Cooking Oil

The production of biodiesel from waste cooking oil (WCO) has been studied by transesterification reaction in an agitated reactor. An alternative to decrease heating and reaction time is to use a hydrodynamic cavitation reactor. The objective of this work was to evaluate biodiesel production in a hydrodynamic cavitation reactor using WCO. A response surface methodology (RSM) was used to find the best experimental conditions. Yield and energy consumed per kilogram of biodiesel produced (ECPKB) surfaces were adjusted. The independent variables were: the methanol-oil molar ratio (6:1 - 5:1 - 4:1) and the percentage of potassium hydroxide catalyst (1% and 0.5%). The flow rate, temperature, electrical energy consumed, and reactor inlet and outlet pressures were monitored. According to the RSM, the optimum production parameters were: molar ratio (MR) 4:1 and 0.5% potassium hydroxide catalyst percentage (KOH). The biodiesel produced was analyzed by a gas chromatography, a cetane index and heat value laboratory tests according to ASTM D6751 standard. Due to high content of methyl esters (above 98%) for 5:1 MR and 0.5% KOH these conditions were selected as the best for production. These conditions led to the highest yield of 1.07 and 74.07 kJ/kg of ECPKB. The reaction time was less than 10 minutes for all conditions, indicating a breakthrough for biodiesel production.