The conversion of soybean oil to biodiesel was performed in a
250 ml flat-bottomed flask, equipped with a reflux condenser and a
magnetic stirrer. The reactor was initially filled with 12.5 g of
soybean oil, which was heated to 65 8C for 3 h while stirring at
300 rpm. The reactant was stirred evenly to avoid splashing in the
flask at the stirring speed. The timing of the reaction was initiated
as soon as the mixture of methanol and the catalyst was added into
the reactor. The effects of molar ratio of methanol to oil (3:1–24:1),
and catalyst/oil weight ratio (1–5 wt.%), on the conversion of
triglycerides to biodiesel were investigated. All of the experiments
were performed at atmospheric pressure. After the transesterification
reaction, DI water was added into the reaction mixture to
stop the reaction. The biodiesel and glycerol layers were easily
separated due to differing densities, of 0.86 and 1.126 g/cm3,
respectively. A supernatant was filtered through a common filter
paper, and then excess methanol and water were evaporated prior
to fatty acid methyl ester (FAME) analysis.