Abstract ▼ AI-Helper

Currently, almost all commercial biodiesel production is done exclusively through homogeneous alkaline catalyst technology. The effectiveness of this technology is reduced by the inability to process low cost feedstock and the need for complex purification operations. There, a more effective and sim...

Currently, almost all commercial biodiesel production is done exclusively through homogeneous alkaline catalyst technology. The effectiveness of this technology is reduced by the inability to process low cost feedstock and the need for complex purification operations. There, a more effective and simplified technology is required to overcome these drawbacks. In this study, we attempted to evaluate the feasibility of a supercritical methanol process for direct production of biodiesel from microalgae. the effects of various factors such as temperature (230-310oC), reaction time (5-50 min), water content(0-300%) and pretreatment (homogenizer, grinding, ultrasonication) on the biodiesel conversion were investigated in detail. The conversion efficiency increased with both temperature and extraction/conversion time. The supercritical methanol process produced a fatty acid methyl ester (FAME) yield of around 88% with 20 minutes. Optimal conditions for this process were found to be a microalgae methanol ratio of around 1:9, a reaction temperature of about 270°C, and a reaction time of approximately 20 minutes. As the temperature increased, the FAME yield gradually increased, and attained a maximum at 270oC. At all reaction temperatures, the percent conversion of C. vulgaris to FAME increased with extraction/conversion time. The optimal extraction/conversion reaction time was found to be twenty minutes in this study. The effect of water content in microalgae samples on the FAME conversion was also evaluated. The supercritical methanol process was not affected by the water content up to 250wt%. It was confirmed that the supercritical process can be applied to oilseeds such as canola and soybean. In situ transesterification of microalgae was also performed to conpare was with the supercritical methanol method. Our experiments demonstrated that the supercritical methanol process is more effective than in situ transesterification. When a mixed supercritical fluid of CO2 and methanol was employed as an extraction/reaction medium, the FAME conversion was observed to decrease as the molar ratio of CO2/methanol increased.