Biodiesel production from canola oil using ultrasonic reactor in small scale circulation process

Currently, most of the biodiesel is produced from vegetable oils and methanol in the presence of base catalysts using mechanical stirring method at temperature 50-65C. This method consumes much energy because oils and methanol must be heated up to desired temperature, and also requires rather long reaction time. Ultrasound-assisted reaction can reduce the reaction time much shorter than mechanical stirring and the reaction can be carried out at room temperature, so energy can be saved. In the pilot scale the trans-esterification was performed by circulation process under low frequency ultrasound (20 kHz) with the input capacity of 1 kW. Effect of various process parameters such as the amount of KOH, molar ratio of oil to methanol and also reaction time were investigated. The optimal conditions for the process were: oil/methanol molar ratio 1:5, the amount of KOH to oil 0.7 % w/w. Under these conditions, conversion of triglycerides to fatty acid methyl esters (FAMEs) was 96.3% within the reaction time 60 minutes . Glycerin, catalyst and excess methanol were separated easily from FAMEs phase. Crude biodiesel was purified by washing with tap water and drying at 65C under reduced pressure at 520torr.