Analysis of a novel high-speed homogenizer technique for methyl ester production using waste cooking oil: Multi-objective optimization and energy analysis

While fossil fuels continue to be the predominant energy source, the use of renewable energy is consistently growing. Biodiesel, with its various advantages over traditional fossil fuels, stands out as a promising alternative fuel that is produced from a sustainable and abundant waste cooking oil (WCO) via a transesterification reaction (due to the low acid value of WCO) with alcohol (MeOH) and homogeneous catalyst (KOH) in a high-speed homogenizer. Biodiesel is produced in the industry using conventional mechanical stirring techniques, which are time-consuming and less efficient. It has been recently reported that high-speed homogenizers have the scale-up potential as per industrial requirements and can significantly reduce the transesterification/esterification reaction time. In the present investigation, the Taguchi technique has been applied for the design of experiments and multi-response process optimization using a composite desirability approach. The optimized values observed for yield, yield efficiency, and pour point were 99.18 +/- 0.2%, 5.4 x 10-3 g/J, and - 14.9 +/- 0.5 degrees C, respectively, at alcohol to oil molar proportion of 7:1, KOH amount of 0.5 wt%, rotor speed of 14000 rpm and 10 min of process time. The physicochemical properties of produced biodiesel were found within EN 14214 and ASTM D6751 standards limits.