waste cooking oil (WCO). Compared with acid catalyzed esterification, the cost of alkali catalyst (NaOH) is low. The process does not
demand expensive anti-corrosion equipment to perform. After the
esterification, no separation of catalyst and excess of glycerol is needed,
and the crude glycerol byproduct and soap as the catalyst can be
recycled. The energy consumption of methanol recovery is reduced by
replacing methanolysis with glycerolysis in the pretreatment. Recycling
test proved that soap maintained its catalyzing activity after being
reused for 13 times. More than 99% of the FFA in the WCO was converted to acylglycerols under optimal conditions (4 h, catalyst loading
0.5 wt.% (based on the WCO weight), 1.4:1 molar ratio of glycerol to
FFA, and 210 °C). After transesterification, the yield of thefinal FAME
product was 93.1 wt.% with a FAME content of 98.6 wt.%. This novel
two-step process for FAME production is a low cost method that can
be used for biodiesel production using oil feedstock with high acid
value (e.g. WCO