The upper layer containing
crude grease and biodiesel was further transferred into a
new reactor for alkaline-catalyzed transesterification at the following
conditions: methanol to grease ratio of 6:1, 0.8% NaOH (w/w)
as the catalyst, 65 C, and reaction time of 30 min. After separation
with a funnel, the biodiesel layer was distilled at 80 C to remove
residual methanol.