Free fatty acid
Formation of soap
Formation of soap inhibits the separation process and also deactivate the catalyst.
Type of alcohol
Methanol Vs. ethanol
-ethanol is more expensive than methanol.
-lower ethyl ester conversion.
Ethanol is difficult to recycle
Viscosity of the ethyl ester is slightly higher than that of methyl ester
Cloud and pour points are slightly lower than that of methyl ester