Direct transesterification of lipids from Microalgae by acid catalyst

Transcription

1 Direct transesterification of lipids from Microalgae by acid catalyst Chemistry Concepts: Acid catalysis; direct transesterification Green Chemistry Topics Alternate energy sources; renewable feedstocks; safer reagents; reduced solvent use Introduction In chem 251 you carried out the Biodiesel synthesis from various oils. This involved the transesterification of oil (triacylglycerides/ lipids) to a less viscous methyl ester product know as biodiesel. A problem with producing large quantities of biodiesel cheaply and quickly is that the oil itself must first be extracted from the plant and this process itself is energy intensive. In this procedure, we will try combine, in one step, the oil extraction from the plant matter and the subsequent transesterification into biodiesel. The source material for the oil will be algae. Algae can contain up to 40% oil and with it fast growth rate may make it a viable renewable energy source. By developing a procedure to extract oil from algae and then to immediately convert in to biodiesel in one pot may make this an economically viable alternative energy. Prelab Copy the reagent table provided into your lab notebook. Reagent Table: Name MW MP BP Density Amt. Used/ Exp. Freeze-dried Algae 100 mg Hexane C 69 C ml g/ml 3 ml Methanol C 65 C Acetyl Chloride Biodiesel g/ml C 51 C g/ml Moles Used/ Exp moles 5 ml moles ml mmoles 30 mg Notes Lipid Content 30% Irritant Toxic Reacts violently with water Corrosive

2 Chemicals and Equipment 50mL beaker, thermometer, round bottom flask, air condenser, drying tube, stir bar, calcium chloride desiccant, 5 ml and 10 ml graduated cylinders, 2-10 ml Erlenmeyer flasks, 15 ml plastic centrifuge tube, glass pipettes with rubber bulb, DI water, amber tubing. Experimental Procedure Prepare a 70 to 80 C hot water bath in a 50mL beaker on a hot plate. Set up a 25 ml round bottom flask equipped with a spin bar, air condenser, and drying tube containing calcium chloride desiccant. Add 100 mg freeze dried Chlorella zofingiensis algae to the flask with 5.0 ml of hexane. Then add 5 ml of methanol and 0.25 ml of acetyl chloride. Be sure to promptly replace the air condenser and drying tube after the addition of the reagents. Lower the apparatus into the prepared hot water bath. Let the reaction proceed at this temperature for 15 to 25 minutes. At the end of this time, transfer the reaction solution to a 15 ml plastic centrifuge tube with cap. Up to 1 ml of additional hexane can be used to wash the flask and complete the transfer. Add 3 ml od DI water to the centrifuge tube and shake the tube gently. Centrifuge for 3 minutes on a setting of 3. To isolate your product extract the upper hexane layer and place in a 25 ml Erlenmeyer flast. Extract the remaining methanol water layer one additional time with 3 ml of hexane. Be sure to mix well and to centrifuge before extracting the upper hexane layer from the tube. Combine the two hexane extracts in the 25 ml Erlenmeyer flask. At this point you may stop and leave this solution to evaporate in your drawer. If time permits, you may evaporate your solution in the hood using a stream of air and a warm water bath below 70 C. Once the hexane has evaporated, weigh the product obtained. Perform IR, NMR and GC/Mass Spec on the product. Cleanup All solids and solutions from above can be placed in the aqueous waste jug.

3 References: Anastas, P. T.; Warner, J. C. (1998) Green Chemistry: Theory and Practice, New York, New York: Oxford University Press. Eroglu, E.; Melis, A. (2010) Extracellular terpenoid hydrocarbon extraction and quantification from the microalgae Botryococcus braunii var. Showa. Bioresource Technology, 101 (7): Lepage, G. and Roy, C.C. (1984) Improved recovery of fatty acid through direct transesterification without prior extraction or purification. Journal of lipid research, 25: Lepage, G. and Roy, C.C. (1986) Direct transesterification of all classes of lipids in a one-step reaction. Journal of lipid research, 27: Li, Yian and Qin, Jian. (2005) Comparison of growth and lipid content in three Botryococcus braunii strains. Journal of Applied Phycology, 17 (6): Mata, T. M.; Martins, A. A.; Caetano, N. S. (2010) Microalgae for biodiesel production and other applications: A review. Renewable and Sustainable Energy Reviews, 14: Metzger, P. ; Largeau, C. (2005) Botryococcus braunii: A rich source for hydrocarbons and related ether lipids. Applied Microbiology and Biotechnology, 66 (5): Samori, C.; Torri, C.; Samori, G.; Fabbri, D.; Galletti, P.; Guerrini, F.; Pistocchi, R.; Tagliavini, E. (2010) Extraction of hydrocarbon from microalga Botryococcus braunii with switchable solvents. Bioresource Technology, 101 (7): Tran, H-L.; Hong, S-J. ; Lee, C-G. (2009) Evaluation of Extraction Methods for Recovery of Fatty Acids from Botryococcus braunii LB 572 and Synechocystis sp. PCC Biotechnology and Bioprocess Engineering, 14:

4 Chemistry 252 Biodiesel from Algae Lab Spring 2012 REPORT GUIDE report due: Weds June 6th, This will not be a formal report.. For the report: 1) Complete the form below and attach NMR, IR and mass spec data. Name Which species of algae did you make your biodiesel from? Mass of freeze dried algal starting material Mass of biodiesel product Color of oil residue Analysis of the NMR spectrum: Analyze the NMR of your biodiesel with the appropriate interpretation. You can write this on the NMR spectrum itself. Comment below if the NMR spectrum indicates that you produced biodiesel. Are there any indications of impurities such as unreacted lipid material or pigments?

5 3. Analysis of the IR spectrum: Analyze the IR of your biodiesel by listing the major absorptions observed and to which functional groups they correspond. You can write this on the IR spectrum itself. Do not report on absorptions found in the fingerprint region. Comment below if the IR spectrum indicates that you produced biodiesel. Are there any indications of impurities such as unreacted methanol? 4. Analysis of the GC/Mass spectrum: On another sheet of paper, list the names and draw the structures of the components in your biodiesel. List only the names of the largest 2 to 4 peaks.