Thesis Archive
Supercritical Carbon Dioxide Extraction of Scenedesmus obliquus Algal Oil for Biodiesel Production
DE JESUS, Richard R.
JOSE, John Vincent M.
MARFA, Mark Gabriel O.
Abstract:
Oil from microalgae is a potential large-scale feedstock for biodiesel production due to advantages over the common crop oil feedstock, especially in terms of land area use. The extraction of oil from microalgae using supercritical carbon dioxide (SCCO2) is gaining increased popularity due to its advantages over conventional solvent extraction, such as high yield of fatty acid methyl ester, or biodiesel, from the oil extracted. This research focused on optimizing extraction parameters in relation to oil yield from the microalga . The fatty acid profile of the oil was also obtained by transesterification of the oil extracted with SCCO2 and compared to the fatty acid profile obtained from in situ transesterification of the biomass. For the study, was cultivated and subjected to centrifugation and drying before the SCCO2 extraction, while a portion was used for in situ transesterification. The temperature, pressure and flow rate of CO2 and the amount of biomass was modified for the different runs using Taguchi design at 45-65°C, 15-25 MPa, and 10-20 mL/min., and the oil yield for each run was measured. The data was analyzed statistically to determine the optimum conditions for highest oil yield. The oils extracts were transesterified and analyzed using GC-FID for their fatty acid profiles and compared with established standards to determine the suitability of the microalga. The study found positive effects in relation to oil yield by increasing the temperature, pressure, and flow rate. The optimum conditions were found by the Taguchi method at 65 °C, 25 MPa, and 20 mL/min. resulting to an oil yield of 5.13%, but lower than the best yield obtained of 5.62% at 55 °C, 25 MPa, and 15 mL/min., suggesting interaction effects. Fatty acid profiles of SCCO2 extracts were mostly similar, with abundance of saturated fatty acids, with exception to a few runs, suggesting little effect of parameters on fatty acid profile, while in situ displayed more unsaturated fatty acids comparatively. Estimation of biodiesel properties showed favorable properties for the oil extracted except for its poor cold flow properties.
Adviser:
AURESENIA, Joseph L.