Alkaline catalyzed esterification process uses the
experimental setup of acid catalyzed pretreatment process.
The products of first step are preheated to the required
reaction temperature of 45G5 8C in the flask. Meanwhile,
5 gm of NaOH is dissolved in 300 ml methanol and is
poured into the flask. The mixture is heated and stirred for
30 min. The reaction is stopped, and the products are
allowed to separate into two layers. The lower layer, which
contained impurities and glycerol, is drawn off. The ester
remains in the upper layer. Methyl esters are washed to
remove the entrained impurities and glycerol. Hot distilled
water (10% by volume) is sprayed over the surface of the
ester and stirred gently. Lower layer is discarded and yellow
color layer (known as biodiesel) is separated.