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

Abstract

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 °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.