Biodiesel fuel production from soybean oil waste as agricultural bio-resource

The study was conducted to investigate the optimum conditions for biodiesel formation from pure (virgin) soybean cooking oil (PSCO) and waste soybean cooking oil (WSCO) coming after alkaline transesterification process in combination with methanol, ethanol and 1-butanol. Some important variables such as volumetric ratio, types of reactants and catalytic activities were selected to obtain a high quality biodiesel fuel with the specification of American Society for Testing and Materials (ASTM D 6751) and European Norm (EN 14214). The highest biodiesel yield (99.6%) was obtained under optimum conditions of 1:6 volumetric oil-to-methanol weight ratio, 1% KOH catalyst at 40o C reaction temperature and 320 rpm stirring speed. The results showed that biodiesel yield from PSCO and WSCO exhibited no considerable differences. But there was a considerable difference of biodiesel yield produced by methanol, ethanol and 1-butanol. The biodiesel yield increased in the order of 1-butanol < ethanol <methanol. There was a bit difference in viscosity, acid value and chemical elements (Ca, Na, P, Fe, Cu, Pb, Mg etc.) between PSCO and WSCO. The research investigated that biodiesel obtained under optimum conditions from PSCO and WSCO was of good quality and could be used as a diesel fuel which considered as potential use of waste cooking oil.