Date of Award
Program or Major
Master of Science
Biodiesel was produced by transesterification of waste olive oil with methanol and NovozymRTM435.
Studies were also performed to evaluate the effect at different acyl acceptors and/or solvents on biodiesel yield. Among the selections, tert-butanol with methanol as the solvent and acyl acceptor gave relatively high yield, while tert-butanol without methanol gave a very low yield. Hexane as the solvent and methanol as the acyl acceptor also gave good yield. While using methyl acetate as both the solvent and the acyl acceptor, the yield was a little low, but still much higher than in tert-butanol without methanol. However, compared to the above selection, the yield of biodiesel with hexane as the solvent and ethanol as the acyl acceptor was as high as 0.63 g biodiesel/g used oil, while the highest yield in the other cases was about 0.43 g biodiesel/g used oil.
Finally, studies on enzyme efficacy were carried out. The efficacy of NovozymRTM435 was determined by reusing the enzyme after washing it with solvent hexane. When methanol was added in one shot (at a ratio of 9:1 with respect to triolein), a slight increase in yield was observed in the second run after the initial first run. The yield then started to decrease progressively for each run beyond the second run, but the activity was still high for the first 6 runs. When methanol was added stepwise at 3:1 * 3, the enzyme underwent slow irreversible inactivation.
For sugar catalyst, feasibility studies were done on its preparation and the activity testing. The conversion of triolein by sugar catalyst was lower than 1%, which indicated that the sugar catalyst activity was very low.
Shen, Xiangping, "Transesterification of waste olive oil by Candida lipase" (2007). Master's Theses and Capstones. 348.