Properties of Biodiesel Produced by Enzymatic Transesterification of Lipids Extracted from Microalgae in Supercritical Carbon Dioxide Medium

Biodiesel, as an alternative renewable fuel, has been receiving increasing attention due to the limited supply of fossil fuels and the increasing need for energy. Microalgae are promising source for lipids, which can be converted to biodiesel. The biodiesel production from microalgae lipids using lipase catalyzed reaction in supercritical CO2 medium has several advantages over conventional production processes. However, identifying the optimum microalgae lipid extraction and transesterification conditions is still a challenge. In this study, the quality of biodiesel produced from lipids extracted from Scenedesmus sp. and their enzymatic transesterification using supercritical carbon dioxide have been investigated. At the optimum conditions, the highest biodiesel production yield was found to be 82%. The fuel properties of the produced biodiesel, without any separation step, at optimum reaction condition, were determined and compared to ASTM standards. The properties were found to comply with the limits, and showed a low glycerol content, without any separation step.

Authors:

• Hanifa Taher
• Sulaiman Al-Zuhair
• Ali H. Al-Marzouqi
• Yousef Haik
• Mohammed Farid

Keywords:

• Biodiesel
• fuel standards
• lipase
• microalgae
• Supercritical CO2.

References:

[1] S. Al-Zuhair, “Production of biodiesel: possibilities and challenges”.
Biofuels, Bioproducts and Biorefining, Vol. 1, pp. 57-66, 2007.
[2] Z.k. Wimmer and M. Zarevcka, “A review on the effects of supercritical
carbon dioxide on enzyme activity”. International Journal of Molecular
Sciences, Vol. 11, pp. 233-253, 2010.
[3] M. Kondo, K. Rezaei, F. Temelli, and M. Goto, “On-line extractionreaction
of canola oil with ethanol by immobilized lipase in SC-CO2”.
Industrial & Engineering Chemistry Research, Vol. 41, pp. 5770-5774,
2002.
[4] Y. Medina-Gonzalez, T. Tassaing, S. Camy and J.S. Condoret, “Phase
equilibrium of the CO2/glycerol system: Experimental data by in situ
FT-IR spectroscopy and thermodynamic modeling”, The Journal of
Supercritical Fluids, Vol. 73, pp. 97-107, 2014.
[5] H. Taher, S. Al-Zuhair, A. AlMarzoqui, Y. Haik, and M. Farid,
“Enzymatic biodiesel production of microalgae lipids under supercritical
carbon dioxide: process optimization and integration”. Biochemical
Engineering Journal, Vol 15, pp. 103-113, 2014. [6] European Committee for Standardization. “Committee for
Standardization Automotive fuels - fatty acid FAME (FAME) for diesel
engines - requirements and test methods”, 2003.
[7] P. Bondioli, and L. Della Bella, “An alternative spectrophotometric
method for the determination of free glycerol in biodiesel”. European
Journal of Lipid Science and Technology, Vol. 107, pp. 153-157, 2005.
[8] K. Krisnangkura, “A simple method for estimation of cetane index of
vegetable oil methyl esters”. Journal of the American Oil Chemists
Society, Vol. 63, pp. 552-553, 1986.
[9] P. Kalayasiri, N. Jeyashoke, and K. Krisnangkura, “Survey of seed oils
for use as diesel fuels”. Journal of American Oil Chemist's Society, Vol.
73, pp. 471-474, 1996.