University of Maiduguri Faculty of Engineering Seminar Series Volume 7, July 2016 Extraction of Biodiesel from Microalgae by Direct In Situ Method S. Kiman, B. K. Highina, U. Hamza and F. Hala Department of Chemical Engineering, Faculty of Engineering, University of Maiduguri. silaskeeman1@yahoo.com; +2347033539116 Abstract Microalgae are promising candidate biomass resources as potential feedstocks for renewable energy production. Microalgae have high biomass productivity, high lipid content, with low cultivation cost. The direct in situ transesterification experiments were carried out to produce biodiesel from microalgae using methanol and n-hexane at a temperature of 60 o C. The result obtained shows that the best in situ transesterification parameters were 3.0wt% H 2SO 4, 5g methanol, and 60 0 C temperatures at high mixing. The variation of time (40, 60, 80, 100 and 120 minutes) and catalyst concentration (1.0, 2.0, 3.0, 4.0 and 5.0wt %) results to biodiesel yield of 53.4, 60.8, 83.4, 74.4 and 64.5% and 48.3, 54.6, 74.8, 68.4, and 60.8% respectively. The optimal yield of biodiesel of the in situ transesterification process parameters used was found to be at 80 minutes and 3.0wt% catalyst. Keywords: Biofuel, Extraction, In situ, Microalgae, Transesterification 1.0 Introduction Microalgae are microscopic unicellular organisms that use sunlight as energy source and CO2 as carbon source to produce biomass, with higher yields than photosynthetic plants (Thompson, 2005; Wen and Johnson, 2009). It has the maximum solar energy conversion capacity of about 4.5% and high photosynthetic rate of about 6.9 x 10 4 cells/ml/h with up to 50 algae biomass constituent of carbon (Dragone et al. 2010; Devi et al. 2012; Munir et al. 2013; Bamba et al. 2014). Microalgae is extensively used today in various businesses and industries including those involved in supplementary health products, waste water treatment, cosmetics, medicine, aquaculture and bioenergy as reported by Hee and Hur (2011). Microalgae have received considerable interest as a potential feedstock for producing sustainable transport fuel that is renewable, carbon neutral and necessary for environmental and economic sustainability with their biotechnological potential (Christi, 2007; Slade and Bauen, 2009). Nigeria has about 67 families, 281 genera and 1335 species of algae (Abuja Report, 2010). Ogbonna and Ogbonna (2015) found that diversifying Nigeria s source of income and choosing a cleaner development pathway through low carbon energy alternatives will potentially contributes to poverty reduction, is possible with some states in the Northern Nigeria like Maiduguri, where the quantity of annual rainfall is too low to support conventional agriculture and thereby leaves an expanse of land with no vegetation over a long period of time. Therefore, many community scale microalgae cultures can be established in such places. Microalgae biodiesel production essentially involves two main steps: Seminar Series Volume 7, 2016 Page 7
1. Extraction of oils from the biomass (Martinez-Guerra et al. 2014), and the oil extraction step includes cell disruption by mechanical, chemical, or biological methods and oil collection by solvent (Park et al. 2014). 2. Conversion (transesterification) of oils (fatty acids) to biodiesel (alkyl esters) (Martinez-Guerra et al. 2014). To date, biodiesel production from algae biomass is generally performed by one of the following methods: -A two-step protocol in which algae oil is extracted and then converted to biodiesel using a catalyst, such as an acid, a base, or an enzyme. -Direct single step in situ production of biodiesel from algae biomass using catalyst The objective of this study is to dry microalgae and use it for the production of biodiesel in a single step in situ method and the determination of optimum catalyst concentration and reaction time. 2.0 Methodology 2.1 Experimental Materials The feedstock used in this research work is microalgae to produce single step transesterification. Materials used during this experiment include the following; - Magnetic stirrer- Model 78-1MHS, Pec medical company, China - Thermometer- Shanghai rex investment factory, China - Measuring cylinder- Simax glass wares laboratory, Czech Republic - Electronic sensitive weighing balance- Model PHS-3C, B-Bran scientific and instrument company, England - 500ml separation funnel- Jaytec company, China - Cotton wood, foil paper and Masking tape - Funnel (glass)- Jaytec company, China - Water bath- Jaytec company, China, Model HH-W21 CR42II - 3 set of 25ml beaker- Simax glass wares laboratory, Czech Republic - 10ml injection syringe - Spatula- B-Bran scientific and instrument company, England - Hexane (extraction solvent)- BDH company limited, England - Sulphuric acid(h2so4)- JHD Guandgua chemical factory limited, China - Methanol- BDH company limited, England 2.2 Experimental Procedure 2.2.1 Drying of algae (biomass) The wet algal biomass was collected from fish pond at the Department of Fishery, University of Maiduguri and was initially air dried then dried in an oven at 55-60 o C for 60 minutes. The dried algae biomass was then subjected to pulverization in mortar for cell disruption followed by mesh sieving. 2.2.2 Biodiesel Extraction The resultant powdered biomass (20g) was pour in to a conical flask along with the measured quantity of n-hexane (100ml) 0.2g of H2SO4 as catalyst and 5g of methanol. The Seminar Series, Volume 7, 2016 Page 8
solution was place on a 78-1 magnetic heat stirrer for agitation and heated for a period of 60 minutes at 60 0 C. This procedure was repeated four more times with variation in the catalyst concentration set at 2.0, 3.0, 4.0 and 5.0wt%. At this point, the simultaneous extraction and transesterification reaction has been initiated; where the catalyst/alcohol solution attacked the triglyceride (oil) in the microalgae strain and cleaved off a fatty acid chain. After the experiment the solution was poured into a separation funnel and was allowed to stand for 30 minutes for separation of the ester (biodiesel) and the glycerol. The denser glycerol was drained followed by draining the ester (biodiesel) in a clean conical flask. The resulting biodiesel was washed with warm water to remove traces of unreacted methanol, catalyst and glycerol till the drained water become clean and it was further purified by heating it at 100-110 0 C for 30 minutes for the removal of any moisture, excess methanol and hexane. Using a constant catalyst concentration of 3wt%, the reaction time was varied at an interval of 20 minutes starting from 40 minutes to 120 minutes. 3.0 Results and Discussion Transesterification reactions were carried out with algae biomass with different reaction conditions, shown in Tables 3.1 and 3.2. The effects of the different process variable, catalyst concentration and reaction time were analyzed experimentally, and optimum transesterification conditions were obtained. 3.1 Effect of Catalyst Concentration One of the most important variables affecting the yield of FAME is the concentration of the acid catalyst. From Table 1, it can be seen that different catalyst concentration yields different amount of biodiesel with the highest yield obtained at a catalyst concentration of 3.0wt%. Further analysis indicates that increasing the amount of catalyst above 3.0wt% reduce the yield of biodiesel because at high catalyst concentration, side reaction are reported to occur which favor the formation of triglyceride instead of biodiesel. Therefore, a catalyst concentration of 3.0wt% can be regarded to be the optimum concentration required for a maximum yield during the single stage transesterification process in this work. Table 1 Effect of catalyst concentration on biodiesel yield at constant time (60 minutes) Run Catalyst Concentrate (%wt) Mass of biodiesel %Yield produced(g) 1 1.0 9.66 48.3 2 2.0 10.92 54.6 3 3.0 14.96 74.8 4 4.0 13.68 68.4 5 5.0 12.16 60.8 3.1 Effect of Reaction Time Another important variable affecting the yield of FAME is the reaction time. Table 2 shows the effect of reaction time on the biodiesel yield. Increasing the reaction time at Seminar Series, Volume 7, 2016 Page 9
constant 3wt% of the catalyst from 40 minutes at interval of 20 minutes resulted to an increasing yield up to the time of 80 minutes, where the peak yield was recorded. Further increment above 80 minutes is seen to reduce the yield of biodiesel; this may be as a result of catalyst deactivation with increasing reaction time. Table 2 Effect of reaction time on biodiesel yield at constant catalyst concentration (3wt%) Run Time (min) Mass of biodiesel produced (g) % yield 1 40 10.68 53.4 2 60 12.16 60.8 3 80 16.68 83.4 4 100 14.56 74.4 5 120 12.9 64.5 4.0 Conclusion In this study, a single step in situ method of transesterification reaction of microalgae was used to produce biodiesel. The effect of reaction time on the biodiesel yield was studied and the various biodiesel yields obtained were 53.40, 60.80, 83.40, 74.40 and 64.50% at variable reaction time of 40, 60, 80, 100, and 120 minutes respectively. The effect of the variation in the amount of catalyst was also studied. The catalyst concentration was varied from 1.0, 2.0, 3.0, 4.0 and 5.0wt%, the biodiesel yield obtained were 48.30, 54.60, 74.80, 68.40 and 60.80% respectively. The catalyst concentration of 3.0%wt and a reaction time of 80 minutes were the optimum operating conditions for this study. References Abuja Report (2010). Fourth National Biodiversity. Available online at https://www.cbd.int/doc/world/ng/ng-nr-04-en.doc. Bamba B., Xiaoxi Y., Paul L., Allassane Q., Maryline A. and Yves L. (2014). Photobioreactor-Based Procedures for Reproducible Small-scale Production of Microalgal Biomasses. J. Algal Biomass Utln., 5(1): 1 14. Christi Y. (2007). Biodiesel from Microalgae. Biotechnology Advances. 25:294 306. Dragone G., Bruno F., António A. V., and José A. T. (2010). Third Generation Biofuels from Microalgae, IBB-Institute for Biotechnology and Engineering, Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga. Devi S., Santhanam A., Rekha V., A Ananth S.,Balaji B., Prasath R., Nandakumar S. and Dinesh K. (2012). Culture and Biofuel Producing Efficacy of Marine Microalgae Dunaliellasalina and Nannochloropsissp. J. Algal Biomass Utln. 3(4):38 44. Hee B. J. and Hur B. S. (2011). Development of Economical Fertilizer-Based Media for Mass Culturing of NannochloropsisOceanica. Fish AquatSci, 14(4):317-322. Martinez-Guerra E., Gnaneswar G. V., Mondala A., William H. and Hernandez R. (2014). Extractive-Transesterification of Algal Lipids Under Microwave Irradiation with Hexane as Solvent, Bioresource Technology 156, 240 247. Seminar Series, Volume 7, 2016 Page 10
Munir N., Sharif I., Shagufta N., Faiza S. and Farkhanda M. (2013). Harvesting and Processing of Microalgae Biomass Fractions for Biodiesel Production (A Review). Science Technology and Development, 32(3):235-243. Ogbonna I. O. and Ogbonna J. C. (2015). Isolation of Microalgae Species from Arid Environments and Evaluation of their Potentials for Biodiesel Production. African Journal of Biotechnology, 14(18):1596-1604. Park, J-Y., Park, M.S., Lee, Y-C. and Yang, J-W. (2014). Advances in Direct Transesterification of Algal Oils from Wet Biomass, Bioresource Technology, doi:http:// dx.doi.org/10.1016/j.biortech.2014.10.089 Slade R. and Bauen A. (2009). Micro-algae cultivation for Biofuels: Cost, Energy Balance, Environmental Impacts and Future Prospects, Imperial Centre for Energy Policy and Technology, Centre for Environmental Policy, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. Thompson P. (2005) Algal Cell Culture, Biotechnology, 1:1 Wen Z. and Johnson M. B. (2009). Microalgae as Feedstock for Biofuel Production. Available online @ www.ext.vt.edu. Seminar Series, Volume 7, 2016 Page 11