Improvement of Biodiesel Transesterification Efficiency by Activated Carbon and Microwave Power*

In this research, the transesterification process to produce biodiesel from waste cooking oil was enhanced by microwave. The positive effect of microwave was even reinforced by the presence of a suitable added amount of activated carbon which helped to increase the microwave absorptivity of the whole reaction system. NaOH was added as the alkaline catalyst for the reaction. The optimum reaction conditions were found as the following: methanol to oil molar ratio 7:1, added NaOH concentration 1.0wt%, added active carbon amount 1.0wt%, microwave power 200W, reaction temperature 65$^{\mathbf{o}}$C and reaction time 120s. The conversion rate of waste cooking oil into biodiesel in these conditions was up to 97.8% which was higher than the Taiwan CNS 15072 standard value of 96.5%.