In situ esterification and biodiesel purification
A batch reactor, equipped with a magnetic stirrer, a water bath
and a condenser system was employed as described by Shiu et al.
(2010). Ten grams of rice bran was mixed with a solution that was
prepared from methanol and sulfuric acid, the mixture was then
put into a 250mL batch reactor at 60 ◦C and atmospheric pressure.
The condenser was inserted into the top of reactor and tap water
was used as the refrigerant. The condenser ensures that methanol
vapor condenses and drips back into the reactor. The mixture was
magnetically stirred at 600rpm and the reaction was carried out
for a predetermined time. The mixture was then filtered by using
replaceable filter. The solid phasewaswashed with 50mLmethanol
and dried overnight at room temperature.
Methanol was removed from the collected liquid phase with an
evaporator. After that, FAMEs was extracted by hexane (3× 50 mL)
from the liquid phase. The hexane extract was washed with water.
The mixture was separated into an upper organic layer and a lower
aqueous layer. The lower layer was removed and discarded. This
liquid–liquid extraction was repeated three times. Residual water
was removed from the pooled organic phase by using anhydrous
magnesium sulfate. After hexane was removed from the pooled
organic layers by using distillation, the substance left was referred
to as the reaction product. The product was analyzed by gas chromatography
and TLC.