Transesterification of castor oil for biodiesel production: Process optimization and characterization

In the present study, batch scale biodiesel production was carried out using castor oil by alkali-catalyzed transesterification process was reported. Initially, the transesterification parameters like reaction time, catalyst concentration, reaction temperature and oil: methanol molar ratio on biodiesel production was optimized by conventional method followed by statistical based central composite design method. According to the optimized experimental results, the maximum of 94.9% FAME yield was obtained at 60 degrees C with 1.25% (w/v) KOH catalyst and 1:12 oil: methanol molar ratio for 60 min of reaction, which was in agreement with the predicted yield (93.7%). The purification of crude biodiesel was performed by simple evaporation and silica gel adsorption. The quality of fatty acid methyl ester was examined by Fourier Transform Infrared spectroscopy (FT-IR), Thin layer chromatography (TLC) and Gas Chromatography-Mass Spectrometry (GC-MS). The analytical results showed that significant quantity of methyl ester groups like ricinoleic, linolenic, palmitic acid and oleic acid were present in the biodiesel.