In this study was developed a new methodology to produce fatty acid ethyl esters from castor oil. The
base-catalyzed transesterification step was followed by on pot addition of sulfuric acid. That addition
implicated the successful separation of FAEEs/glycerin phases due to soap breaking. The study was carried
out through an experimental design where the variables studied in the first step were the molar ratio
alcohol:oil and the catalyst amount in the transesterification process. As expected, the on pot addition of
concentrated sulfuric acid yields FFAs that increase the acid value in the FAEEs phase. A second step esterification
of these free fatty acids from FAEE raw mixture was investigated. The esterification of FFA was
carried out in 60:1 and 80:1 M ratios (alcohol:free fatty acids) and concentrated sulfuric acid 5% and
10% w/w (based on free fatty acids). Consequently, these two steps yielded more fatty ethyl esters and
assure that the following important requirements in the FAEEs production process from castor oil are satisfied:
complete reaction, best separation of FAEEs/glycerin phases, removal of catalyst, limpid glycerin,
and absence of free fatty acids.