Transesterification by basic catalysis,using vegetable oils and animal fats that have appreciable amounts of free fatty acids,is disadvantaged by soap formation,which prevents the separation of biodiesel from the glycerin phase
In order to reduce the amount of free fatty acids,Canak ci and Van Gerpen [2] proposed a method for the production of biodiesel from oils and fats with high levels of free acidity through a pre-treatment,based on an esterification reaction using acid catalyst,followed by the us ual transesterification.