Production of Biodiesel from a Mixture of Microalgae Oil and Sunflower Oil

Transcription

1 Production of Biodiesel from a Mixture of Microalgae Oil and Sunflower Oil Christeena Mathew 1 and Dr. S. Sankar 2 1 Energy Systems, Nehru College of Engineering and Research Centre, Pampady, India 2 Associate Professor, Department of Mechanical Engineering, NCERC, Pampady India ABSTRACT International Journal of Research in Mechanical Engineering Volume 4, Issue 3, May-June, 2016, pp Online: Print: , DOA: IASTER 2016, This paper discusses a detailed study on the production of biodiesel using a mixture consist of spirulina micro algae oil and sunflower oil in three different volume percentage say 5:95ml, 10:90ml and 15:85ml through two-step trans-esterification process. The first step called pre- esterification process was done by using 0.5% of the oil weight of sulphuric acid and 20% of the oil weight of methanol at 60ºC reaction temperature and 120 minutes of reaction time to reduce the FFA level less than 1%. The second step called tras-esterification reaction is carried out using 20% of oil weight of methanol with potassium hydroxide (KOH) by 1% of the oil weight as alkaline catalyst at 60ºC reaction temperature and 120 minutes reaction time to produce the bio-diesel. The lower viscous biodiesel produced in different ratios through trans-esterification process were blended with conventional diesel in 10% ratio. The study also includes examination of physical and chemical properties such as ph value, viscosity, density, flash point, fire point and acid values on the produced biodiesel as well as on the conventional diesel for comparison. The study revealed that the properties of the bio-diesel are very close to the conventional diesel Keywords: Biodiesel, Micro Algae, Pre-Esterification, Sunflower Oil, Trans-Esterification. 1. INTRODUCTION Continued use of petroleum sourced fuels is now widely recognized as unsustainable because of depleting supplies and the contribution of these fuels to the accumulation of carbon dioxide in the environment. Renewable, carbon neutral, transport fuels are necessary for environmental and economic sustainability. Biodiesel derived from oil crops is a potential renewable and carbon neutral alternative to petroleum fuels [5]. Global warming, or climate change, is a subject that shows no sign of cooling down. Since the mid-20th century it has projected continuation. Earth is already showing many signs of worldwide climate change. The major disadvantage of using petroleum based fuels is atmospheric pollution created by the use of petroleum diesel. Petroleum diesel combustion is a major source of greenhouse gases [7].The characteristics of biodiesel reduce the emissions of carbon monoxide (CO), hydrocarbons (HC) and particulate matter (PM) in the exhaust gas as compared with petroleum diesel, so is environmentally beneficial [2]. Biodiesel is a green alternative liquid diesel fuel derived from vegetable oils or lipids by the reaction with alcohol in the presence of a catalyst. Biodiesel is used today as the basis for a clean substitute for petrol-diesel without any modification in diesel engines [10]. GHG contributes not only to global warming (GW) but also to other impacts on the environment and human life. Oceans absorb approximately one-third of the CO2 emitted each year by human activities and as its levels increase in 75

2 the atmosphere, the amount dissolved in oceans will also increase turning the water ph gradually to more acidic. This ph decrease may cause the quick loss of coral reefs and of marine ecosystem biodiversity with huge implications in ocean life and consequently in earth life [8]. Microalgae growth occurs when microalgae use light as energy source, and inorganic carbon as chemical bricks to synthesize chemical compounds through photosynthesis. The light used for the microalgae cultivation may come from sun, conventional lamps or LED lights [6].Biodiesel is produced currently from plant and animal oils, but not from microalgae. This is likely to change as several companies are attempting to commercialize micro algal biodiesel. Biodiesel is a proven fuel. Technology for producing and using biodiesel has been known for more than 50 years [5]. Growing bio-diesel could be a sustainable process, using the energy of the sun and waste carbondioxide to produce useful lipids that can be processed into bio-diesel fuel. This could be a useful natural solar panel transforming sunlight into the chemical energy of oil. Our reliance on fossil fuels has caused carbon dioxide enrichment of the atmosphere, and is the primary contributor to the generally-accepted phenomenon called global warming. Because using coal produces even greater CO 2 emissions than oil, the depletion of oil will be unlikely to improve this pattern of CO 2 enrichment. In order to realize a stable energy alternative that will meet world demand while mitigating climate change, it is necessary to develop renewable clean fuels [7]. In the conventional trans-esterification process, Sunflower oil, micro algae oil methanol and KOH in various concentrations were refluxed together in a 500 ml round bottom flask equipped with magnetic stirrer and water condenser. After the complete conversion of the oil, the reaction was stopped and the mixture was allowed to stand for phase separation: the ester mixture formed the upper layer and glycerine formed the lower layer. The residual catalyst and unreacted alcohol were distributed between the two phases. After phase separation, using a separating funnel, the ester mixture was dried over anhydrous sodium sulfate. 2. MATERIALS AND METHODS 2.1 Collection of Micro Algae Microalgae were got from central marine fisheries and research institute (CMFRI), Ernakulam.The species of micro algae chosen was spirulina. 2.2 Culture Media Preparation for Lab Culture Table 1.Micro Algae Culturing Conditions Parameters Range Optima Temperature (C 0 ) Salinity (g/l) Light Intensity (Lux) ph Aquatic cultures of microalgae were prepared in 5 numbers of 1000 ml conical flasks. The rate of growth of these algal species was measured by compound microscope. Experiments were conducted in the month of january with light intensity of 100 lux and 25 C of average temperature. Algal cultures must therefore be enriched with nutrients to make up for the deficiencies in the water. The following are the paoletti medium was used for microalgal culture. Culture period is 2 weeks which depends on the temperature. 76

3 Table 2.Paoletti Medium Macro nutrients Gm/L NaCl 0.92 Na 2 S KH 2 PO Na 2 CO NaHCO CaCl 2.H KNO MgSO 4.7H Micro nutrients Gm/L H 3 BO MnSO 4.H ZnSO 4.7H NaMoO 4.2H CuSO 4.5H CoCl.6H Fe EDTA Stock solution Gm/L EDTA Na FeS0 4.7H Macro nutrients-1ml Micro nutrients-1 ml Fe EDTA stock-1 ml 2.3 Mass culture of Micro Algae Figure 1.Micro Algae Cultivation under Laboratory Condition Mass cultures of microalgae were prepared in 4 numbers of open tanks with 500 liter capacity. Light supplied by sun. Also needs 400L water, medium, and aerator, net for covering. Mixing is achieved by aerator. 30 gm of sodium bicarbonate and 3 gm of N: P: K and spirulina culture equally added to the open tanks. Mixing is necessary to prevent sedimentation of the algae, to ensure that all cells of the population are equally exposed to the light and nutrients, to avoid thermal stratification (in outdoor cultures) and to improve gas exchange between the culture medium and the air. Figure 2 shows the micro algae cultivation in open tanks. 77

4 2.4 Harvesting Figure 2. Micro Algae Cultivation in Open Tanks Prior to lipids extraction, the microalgae must be separated from the culture media. Filter is used to separate the micro algae from culture medium. The wet micro algae were dried by oven at 60 0 C. 2.5 Lipid Extraction Soxhlet method is used to extract the lipid from micro algae. The organic solvents n-hexane was used. A mass of 20gm of dry microalgae was extracted with 150 ml of solvent. This type of extraction is based on the evaporation, condensation and percolation of the solvent through the microalgae during 4 hours [6].After that, solvent was removed and lipids recovered by water bathing process. Figure 3 shows the soxhlet apparatus for lipid extraction. The total lipid content of Spirulina microalgae was obtained to be g/g biomass. Figure 3. Soxhlet Apparatus 2.5 Mixing of Microalgae Oil and Sunflower Oil Microalgae oil and sunflower oil are mixed thoroughly in different ratios and checked the viscosity using redwood viscometer and density by density meter. The mixing ratios, observed value of viscosity and density are presented in the table Table 3. Viscosity of Oil at Different Mixing Ratio Mixing Ratios Viscosity (at 50 0 C) Density(kg/m 3 ) Micro algae oil 9.18mm 2 /s 930 Sunflower oil 7.77 mm 2 /s 919 5ml micro algae oil +95ml sunflower oil 8.26 mm 2 /s ml micro algae oil +90ml sunflower oil 8.54 mm 2 /s ml micro algae oil +85ml sunflower oil 9.05 mm 2 /s Pre-esterification Process The mixed oil has high free fatty acids (FFA) and requires pre-treatment. In pre -esterification process the mixed oil is react with 20% v/v methanol and 0.5% v/v acid catalyst at 60 0 C. The reactions were carried out using a 500ml round bottom flask equipped with a reflux condenser, and magnetic stirrer. The experiments were performed at methanol temperature reflux. The round bottom flask was filled with algae oil, sunflower oil, acid catalyst and methanol and heated under constant agitation speed of 78

5 1500 rpm for 1.5 hours. The pre- esterification was carried out to reduce algae oil acidity from 29 % to less than 1 %.After completion of the reaction, the mixture was filtrate to remove catalyst and the excess of methanol was recovered by washing. Add sodium sulfate for remove the water content of the oil. The acid value was determined by titration method. Acidity (%) = x 100 (1) Where v = volume (ml) of KOH solution; n= normality, m=sample weight 2.7 Trans-Esterification Process In trans-esterification process measured 0.5 gram of KOH. Measured quickly since the catalyst absorbs water from the atmosphere rapidly and this water can interfere with the trans-esterification reaction. Then, mix the KOH with 20 ml of methanol in a sturdy, heat proof glass bottle with a narrow neck to prevent splashing. Constantly mix or stir the solution to quickly dissipate the heat given off by the reaction. The mixing process takes about 15 minutes, pour 100ml of mixed oil in the container, and heat the container to about 50 o C. The trans-esterification reactions were carried out using a 500 ml round bottom flask equipped with a reflux condenser, and magnetic stirrer. The experiments were performed at methanol temperature reflux. The round bottom flask was filled with algae oil, sunflower oil, KOH and methanol and heated under constant agitation speed of 1500 rpm for 1.5 hours. Keep the temperature below 60 o C since methanol will boil at 65 o C and will be lost. Then allow the mixture to settle overnight. The system should be closed to the atmosphere to prevent loss of methanol during the reaction. The reaction will take about 12 hours to complete. Figure 4 shows the trans-esterification reaction. Figure 4.Experimental Setup Figure 5. Trans-esterification Reaction [5] 2.8 Separation As soon as the reaction is completed, pour the mixture from the round bottom flask into a separating funnel for settling and screw on the lid tightly. Allow the mixture to settle hours. After settling, there will be two phases in the bottle with a clear interface. Darkcolored glycerol byproduct will collect at the bottom, with crude biodiesel on top. The biodiesel varies in color depending on the oil used. Carefully remove the bottom layer. Be sure to not inadvertently mix up the glycerol layer with the biodiesel. Figure 6.Biodiesel and Glycerol after Trans-Esterification 79

6 2.9 Crude Biodiesel Washing and Filtering The crude biodiesel still contains contaminants such as soaps, excess methanol, residual catalyst, and glycerol. It can be purified by washing with warm water to remove residual catalyst or soaps. The Bio-diesel was washed by 5% water until it was become clean. The washing procedure is effective because the residues are more readily dissolved in water. The ester mixture was dried over anhydrous sodium sulfate [4].. In filtration process, it is filtered with the use of a filter paper. 3. RESULT AND DISCUSSION Figure 7. Purified Biodiesel Table 4 shows that the properties of biodiesel and conventional diesel. The study shows that the properties of the bio-diesel are very close to the conventional diesel. Parameters Table 4. Properties of Biodiesel and Conventional Diesel Biodiesel (5ml+95 ml) (algae oil + sunflower oil) Biodiesel (10ml+90ml) (algae oil + sunflower oil) Biodiesel (15ml+85 ml) (algae oil + sunflower oil) Diesel Density(kg/m 3 ) Viscosity (mm 2 /s) (50 0 C) Acid Value (mg/koh gm) Flash point (K) Fire point (K) ph CONCLUSION From the above study, the following conclusions can be deduced: At the very first, micro algae oil which is used for biodiesel production is manufactured successfully. Also, the produced algae oil and readily available sunflower oil were tested individually for their properties. In this study, the importance of continuously investigating the effect of biodiesel blends with pure diesel is investigated experimentally. The combination of both the algae oil and the sunflower oil may be used as resource to obtain biodiesel. In this way micro algae and sunflower oil can be used as renewable energy. The experimental result shows that the trans-esterification is a promising area of research for the production of biodiesel in large scale. The study also revealed that the properties of the bio-diesel are very close to the conventional diesel. Micro algae and other biodiesel feedstock shall be cultivated exclusively for the purpose of biodiesel production, so that the cost of the oils from these feedstock used for other purposes do not change. 80

7 5. ACKNOWLEDGEMENT It is a great pleasure for me to acknowledge all those who have assisted and supported me to lead my project to success. First of all, I would like to thank god almighty for blessing me with his grace and taking my endeavour to a successful culmination. I extend my sincere gratitude towards to Dr.S Sankar, Associate Professor, Department of Mechanical Engineering, Nehru College of Engineering and Research Centre, who gave me immense support and knowledge for completing the project on time. Also, I would like to thank Integrated Rural Technology Centre (IRTC) Mundur, Palakkad- Kerala and NGI Centre for Research in Engineering Design, Green Manufacturing and Computing (CRDGC), Pampady, Thrissur, Kerala for permitting me to use their facility for the completion of this project. I finally thank my parents, family members and friends for their moral support. REFERENCES [1] Harriet Volkmann, Ulisses Imianovsky, Jorge L.B. Oliveira, Ernani S. Sant Anna, Cultivation of Arthrospira (Spirulina) Platensis in Desalinator Wastewater and Salinated Synthetic Medium: Protein Content And Amino-Acid Profile, Brazilian Journal of Microbiology, 39(1), 2008, [2] Soha S.M. Mostafa A, Nour Sh. El-Gendy, Evaluation of Fuel Properties for Microalgae Spirulina Platensis Bio-Diesel and its Blends with Egyptian Petro-Diesel, Arabian Journal of Chemistry, 34(7) 2013, [3] El Shimi, H, Attia, N, El Sheltawy, S, El Diwani, Reactive Extraction of Microalgae for Biodiesel Production; and Optimization Study, Research Journal of Chemical and Environmental Sciences, 2 (4), 2014, [4] M. Thirumarimurugan, V. M. Sivakumar, A. Merly Xavier, D. Prabhakaran, and T. Kannadasan, Preparation of Biodiesel from Sunflower Oil by Transesterification, International Journal of Bioscience, Biochemistry and Bioinformatics, 2(6), 2012, [5] Yusuf C., Biodiesel from Microalgae, Biotechnology Advances, 25(3), 2007, [6] Angel S, Angeles C, Rocío M, Víctor A., Lipids Extraction From Microalgae For Biodiesel Production, IEEE International Renewable and Sustainable Energy Conference, 2014, [7] Annam A, Joshua A, Ananthi P, and Joe k., Production of Biodiesel from Marine Macro algae., IEEE International Conference on Recent Advances in Space Technology Services and Climate Change, 2010, [8] Teresa. M. Mata, Antonio. A. Martins, Nidia S Caetano., Micro Algae for Biodiesel Production and Other Applications: A Review, Renewable and Sustainable Energy Reviews, 14(1), 2010, [9] Farooq Ahmed, Amin U. Khan and Abdullah Yasar., Transesterification of Oil Extracted from Different Species of Algae for Biodiesel Production, African Journal of Science and Technology, 7(6), 2013, [10] H. I. El-Shimi, Nahed. K. Attia, S. T. El-Sheltawy, G. I. El-Diwani., Biodiesel Production from Spirulina-Platensis Microalgae by In-Situ Transesterification Process, Journal of Sustainable Bioenergy Systems, 3(3)2013,