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Determination of physico chemical properties of castor biodiesel  a potential
 

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    Determination of physico chemical properties of castor biodiesel  a potential Determination of physico chemical properties of castor biodiesel a potential Document Transcript

    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME101DETERMINATION OF PHYSICO-CHEMICAL PROPERTIES OFCASTOR BIODIESEL: A POTENTIAL ALTERNATE TOCONVENTIONAL DIESELR.SRUTHI*1, K. RAVI KUMAR2, G. SHIRISHA31Asst Prof., Department of Petroleum Engineering, AHCET, Chevella,Ranga Reddy – 515002(A.P.), India.2Asst Prof., Department of Mechanical Engineering, AHCET, Chevella,Ranga Reddy – 515002(A.P.), India.3Asst Prof., Department of Mechanical Engineering, AHCET, Chevella,Ranga Reddy – 515002(A.P.), IndiaABSTRACT:Depletion of world’s crude oil reserves, increasing crude oil prices, negative effects ofmineral and synthetic oils on man. Biodiesel is receiving increased attention as an alternative, non-toxic, biodegradable and renewable diesel fuel and contributes a minimum amount of net green housegases, such as CO2, SO2 and NO emissions to the atmosphere. Exploring new energy resources, suchas biofuel is of growing importance in recent years. The possibility of obtaining oil from plantresources has created a great importance in several countries. Vegetable oil after tansesterificationbeing used as bio diesel. Considering the cost and demand of the edible oil is bearable, so it may bepreferred for the preparation of bio diesel in India.In the present study castor oil was exctracted from seeds through soxhlet extraction, fatty acidmethylesters was synthesized with methanol, KOH as a base catalyst. Product was confirmed with1HNMR spectra, physico-chemical properties were determined for oil and its methylesters to comparethe properties. Physico-chemical properties demonstrate that methylesters are exhibiting improvedand excellent properties than its oil for bio-diesel purpose. Thermo-oxidative stability and cold flowproperties were also found, which is showing satisfactory results. From this study it was concludedthat castor oil can be used as a potential alternate to conventional diesel...1. INTRODUCTIONGradual depletion of world fossil reserves and emissions of green house gasses are leading toenergy insecurity and ecological imbalance in future. Biodiesel derived from renewable resources i.evegetable oils seems to be a resolution as it is ecofriendly in nature.INTERNATIONAL JOURNAL OF ADVANCED RESEARCH INENGINEERING AND TECHNOLOGY (IJARET)ISSN 0976 - 6480 (Print)ISSN 0976 - 6499 (Online)Volume 4, Issue 3, April 2013, pp. 101-107© IAEME: www.iaeme.com/ijaret.aspJournal Impact Factor (2013): 5.8376 (Calculated by GISI)www.jifactor.comIJARET© I A E M E
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME102Biodiesel can be defined as basically monoalkyl esters of fatty acids produced from animal fats orvegetable oils by transesterification or other methods with small chain alcohols, using different kindsof catalysts [1]. Currently, more than 95% biodiesel are produced from edible oil feedstock, due tothis there is a huge imbalance in the human nutrition chain versus fuel [2]. This will make biodieseleconomically unfeasible as compared to petroleum-derived fuels [3,4]. To avoid these situations, non-edible oil seeds need to be used for commercial production of biodiesel. Many researchers haveinitiated work on the use of low cost non-edible oils as alternative feedstock for biodiesel production[5,6,7]. Among non-edible oil feedstock, seeds of castor proved to be a one of the highly promisingreliable source having high seed oil content. Castor oil is non-edible due to presence of toxic phorbolesters and curcin [9].Therefore, in the present paper efforts has been made to extract the oil from castor seeds,synthesis of its fatty acid methylesters, determination of physico-chemical properties (fuel properties)and thermo-oxidative stability analysis of castor for exploration of potential biodiesel sources.2. MATERIALS AND METHODS2.1. MaterialsCastor seeds were separated from the fruit mechanically and cleaned manually to remove allforeign material. The cleaned seeds were dried at 60OC temperature. Pure standards of FAME waspurchased from M/s Sigma Aldrich. All other chemicals and reagents (methanol, ethanol, n- hexane,potassium hydroxide, and phenolphthalein indicator were analytical reagent grade and purchased fromM/s Merck.2.2. Extraction procedure of Castor oilCastor oil was extracted in soxhlet apparatus using n-hexane as per the standard AOCS(American Oil Chemical Society) procedure for 8 h. The extract was concentrated in rota vapor, theresidual oil was cooled and weighed. The physico-chemical properties of the oil were determined.2.3. Transesterification of Castor oilDue to low acid value of the oil direct transesterification procedure was followed.Transesterification reaction was carried out in 250 ml three necked glass vessels (3 mm thick) sealedtightly and fitted with condenser at the top. The reaction glass vessel was placed on the hot platemagnetic stirrer. Methyl esters of Castor seed oil were prepared by refluxing the oil at 60OCemploying a 1:6 molar ratio of oil to methanol for one and half hour with 1 wt% KOH as catalyst andthe mixture was stirred using a magnetic stirrer at 400 rpm [10]. After completion of the reaction, themixture was cooled to room temperature and poured in a separating funnel, leading to separation oftwo phases. The bottom glycerol layer was discarded and the top ester layer was washed gentlyseveral times with warmed water to remove the catalyst, glycerol, and soap. A pH meter was used tocheck the complete removal of the catalyst. The washed methyl ester was further purified undervacuum on a rotary evaporator.2.4. 1H NMR spectroscopy1H NMR spectrum of Castor oil and the fatty acid methyl esters was obtained on 500 MHzNMR spectrometer. Samples were dissolved in 400 ml deuterated chloroform (CdCl3) and transferredto the 5-mm NMR tube. The deuterated chloroform chemical shift peak at 7.26 ppm was taken asinternal reference. Typical parameters used were: spectral width: 4800 Hz; time domain data points:32 K; flip angle: 90O; relaxation delay: 5 s; spectrum size: 32 K points; and line broadening forexponential window function: 0.3 Hz.
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME1032.5. Thermogravimetric analysis (TGA)The thermogravimetric profile of castor oil and its methyl esters was obtained usingThermogravimetric Analyzer at the heating rate of 10 OC/min in both nitrogen and air atmosphere.The sample size was kept almost same 5 to 6 mg throughout the study.3. RESULTS AND DISCUSSION3.1. Physiochemical characterization of castor oilThe physico-chemical characteristics of oil was estimated as per the ASTM standard methods.Initially, the specific gravity of the oil sample was determined using the standard method mentionedabove. Specific gravity of castor oil was found to be 0.875, which is within acceptable range ofstandard ASTM specifications. Similarly, viscosity of oil sample was measured using a standardprotocol. Viscosity of the oil increases with increase in molecular weight and decreases with increasein unsaturation level and temperature [19]. The kinematic viscosity of the oil at (40 OC) was found tobe 75.40 cst respectively, which is much higher as compared to conventional diesel . These highviscosity oils cannot be used directly in engine. High viscosity causes injector fouling and otherengine operational problems. Therefore, before application in diesel engine, processing is required toreduce the viscosity of the oil. The flash point of the oil was found to be 314. The result shows thatthe flash point of oil sample is much higher as compared to conventional diesel. Similarly, the firepoint of oil was found at 333 OC which is much higher than diesel. Refractive index is the degree ofthe deflection of a beam light that occurs when it passes from one medium to the other. The refractiveindex value increases with the degree of unsaturation. Refractive index was found to be 1.46.Moisture content of oils was determined using Karl fisher titrator. Moisture content is a qualitativeparameter of oil, which influences the storage life of fuel. High moisture content may serve as amedium for microbial growth. Microbial growth in the oil may leads to damage of tank and emulsionformation [20]. Besides this, it initiates oxidation of oil which effects longetivity of engines andreduced shelf life of the oil. The moisture content of the oil was found to be 0.33 which are withinacceptable range of standard values. The flow characteristic of oil was observed under lowtemperature. The pour point of 7 OC was observed. The calorific value for the oil was measured in anoxygen bomb colorimeter. The data obtained from experiment for castor oil showed high calorificvalue in the range of 35.46 MJ/Kg. The acid value of the oil determines the process oftransesterfication i.e. either one step or two step process [21]. The acid value of the castor oil wasmeasured to check the free fatty acid content in the oil sample, and it was found to be 3.23 mg/KOH.As per the values reported in the literature FFA content of castor oil varies in the range of 4 to40 which is far beyond the capacity of conversion to biodiesel via single step alkali catalyzedtransesterification. But in the present study FFA content of oil was found to be very less. So, singlestep alkali catalyzed reaction was performed for conversion of oil in to biodiesel. This single steptransesterification yields substantially higher conversion rate and decreased the reagent use andreaction time as compared to two step transesterification process. The high FFA content increases theformation of fatty acids salts (soap) and conversion rate decreased which cause problem in separationof glycerol at washing step.3.2. Characterization and evaluation of synthesized methyl estersThe fuel properties of methyl esters of castor oil was determined using the standard protocol.During the study it was observed that the specific gravity which influences the fuel atomization [21]was reduced after methanolysis. The obtained values for methyl esters castor oil was within theacceptable range of ASTM standards . As described above the viscosity which is the major problem inthe oil samples for engine operation was substantially decreased after transesterification. Thedecreased value of the viscosity was found to be 12 cst. The values are almost within the acceptablerange of ASTM standards . Similarly, flash and fire point values were also found to be reduced aftertransesterification and the obtained Values are in the range of 185 and 190 OC respectively.
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME104Fig.1 1H NMR spectrum of castor oil and methyl esterSince, flash point and fire point values are depends on viscosity, therefore, decrease in theviscosity values after transesterification might be one of the cause for reduction. Acid value is anothermeasure of qualitative character of biodiesel. As per the ASTM standard, acid value of transesterifiedproduct should not be more than 0.5 mg KOH/g. The acid values of the methyl esters of the castor oilsample in the present study was found to be 0.46 mg KOH/g, which is below the maximum limits ofthe standards . Similarly, the moisture content of the prepared methyl esters samples was determinedusing Karl fisher titrator. After transesterification the moisture content of methyl esters was found tobe 0.25% , which is well below the maximum acceptable limits. Cold flow properties such pour pointof methyl ester was found to be improved after transesterification. Pour point of methyl esters wasmeasured as 2 OC. But these values are still much higher than the conventional diesel. The heatingvalue is one of the essential properties for evaluation of biodiesel, which provides the suitability offuels as alternative to diesel fuels [25]. Calorific value for methyl esters was obtained as 41.36 MJ/Kg.The result shows that calorific value of methyl esters is higher than the corresponding oils . All theseproperties combined together have shown that castor oil could act as the potential candidates forbiodiesel production.3.3. 1H NMR spectroscopyNuclear magnetic resonance (NMR) spectroscopy was employed to monitor thetransesterification reaction. In case of 1H NMR spectra of methyl esters, signal appears in the regionat 3.7 ppm which indicates the presence methylic esters group [27]. The characteristic peak ofmethoxy protons was observed as a singlet at 3.65 ppm and this signal was attributed to methyl esters,which was absent in the oil. In case of 1H NMR spectra of oil, multiple peaks were observed in theregion 4.11-4.115, 4.266-4.306 ppm and 5.30-5.34 ppm, due to oxymethylic hydrogen that arecharacteristic of triglycerides. 1H NMR spectrum of castor methyl esters, the strong singlet peak at3.659 ppm is indicative of conversion of parent oil to methyl esters. So, from the NMR spectrum ofoil and methyl esters, it could be verified that castor oil conversion into biodiesel was successfullycompleted.3.4. Thermal stability of castor oil and methyl estersThermal stability of castor oil and its methyl esters was determined from onset temperature ofthermal decomposition under nitrogen atmosphere. The curve shows three consecutive stages ofthermal decomposition of the oil samples. The first phase of decomposition start at 310-315 OC andsecond phase extended up to 470 OC which leads to rapid weight loss. The final stage ofdecomposition, where pyrolyzed product of second phase fully decomposed extended from 470 to 700OC. In the first stage evaporation starts at 240-280 OC, extended up to 540 OC where rapid weight loss
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME105was occurred. Final decomposition occurred between 540 and 700 OC. TGA analysis of methyl esterssamples was carried out under similar condition.Fig.2- TGA profile of castor oil and methyl esters under nitrogen environmentFrom the TGA curves of the oil samples and methyl esters it was observed that, the process ofdegradation of castor methyl esters initiates and completed within a temperature range inferior to therespective oil sample. Molecular tension produced by bulky triglycerides molecule in the oil samplewhich could be the reason for thermal stability of oil [28]. Besides this, high viscosity might be thereason for slow degradation process [15]. The poor volatility and high viscosity of the oils are themajor challenges to run modern diesel engines with plant oils. The onset temperature for volatilizationand distillation was calculated from respective TGA curves of castor oil and methyl esters. The resultshows that onset temperature of thermal degradation of methyl esters was lower as compared to oilsample. In case of oil sample weight loss was negligible below 300 OC. But after that rapiddegradation was observed at 310 OC compared to its methyl esters at 120 OC. During this study it wasobserved that for oil sample 50% weight loss was occurred at around 420 OC , while in case of methylesters it was around at 280 OC. All the volatile components of the oil which accounted for almost 90%weight were decomposed at around 440 OC, whereas in case of respective methyl ester 90% weightloss was observed at 295 OC. The remaining 10% was pyrolysis product which is highly viscousliquids, under goes secondary decomposition. The temperature for secondary decomposition extendedup to 470-530OC for oil and 320-380 OC for methyl esters. The residue was completely burnt out afterheating up to 700 OC for both oil and methyl esters. The above data confirms that oil is more thermallystable and less volatile as compared to methyl esters. Further it is also confirmed that methyl estersshows close proximity with conventional diesel.3.5. Oxidative stability of Castor oil and methyl estersOxidative stability is the quality indicative parameter for methyl esters. It is defined as theresistance of the oil against oxidation.Fig.3- TGA profile of castor oil and methyl esters under oxygen environment
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME106The consequence of lipid oxidation results in decreasing the shelf life of the oil. The oxidationof long chain methyl esters initially results in accumulation of hydro peroxides. Then gradually itpolymerizes forming insoluble sediments that plugged filters, fouled injectors and interfered withengine operation [15]. To measure the oxidative stability of the oil as well as methyl esters TGAanalysis was performed in air atmosphere under same conditions. During the analysis it was observedthat the onset temperature of oxidative degradation for oil sample was 230 OC, whereas, in case ofmethyl esters it was 120 OC. That is mainly because methyl esters are less viscous than oil. This lowviscosity increases the contact between oxygen and ester molecules resulting higher oxygen diffusion[29]. The vegetable oil contains naturally occurring antioxidants such as tocopherols, sterols andtocotrienols, but the purification process destroys these natural antioxidants and hence becomes proneto oxidation [30]. The oxidative stability of methyl ester can be improved either by using syntheticantioxidants which are available in market or vegetable oil based antioxidant additives. So, furtherresearch and development on castor oil based biodiesel will make it more attractive to replace fossilfuels.4. CONCLUSIONSCurrent investigation on the oil content and fuel properties of castor oil provides valuableinformation on potential resources for biodiesel production. Physicochemical characterization of oiland methyl esters established the suitability of the biodiesel to use in diesel engine. The castor oilused in the present study showed low level of FFA, therefore single step alkali catalyzedtransesterification was found to be sufficient for biodiesel production. From the study it can beconcluded that castor oil can be used for large scale propagation and cost-effective biodieselproduction. However, more extensive and experimental study needs to be carried out to investigatecombustion, emission characteristics and its performance on Engine. Therefore, we still need to focuson the process design, and kinetics of castor oil transesterification in a batch reactor and analysis inbiodiesel- fueled engine to establish castor biodiesel as successful alternative fuel.REFERENCES[1]Knothe G. Analyzing biodiesel: standards and other methods. J Am Oil Chem Soc2006;83:823e33.[2] Gui MM, Lee KT, Bhatia S. Feasibility of edible oil vs. nonedible oil vs. waste edible oil asbiodiesel feedstock. Energy 2008;33:1646e53.[3] Wang Y, Ou SY, Liu PZ, Tang SZ. Comparison of two different processes to synthesize biodieselby waste cooking oil. J Mol Catal A Chem 2006;252:107e12.[4] Zhang Y, Dube MA, Mclean DD, Kates M. Biodiesel production from waste cooking oil: 2.Economic assessment and sensitivity analysis. Bioresour Technol 2003;90:229e40.[5] Akbar E, Yaakob Z, Kamarudin SK, Ismail M, Salimon J. Characteristic and composition ofJatropha curcas oil seed from Malaysia and its potential as biodiesel feedstock. Eur J Sci Res2009;29(3):396e403.[6] Karmee SK, Chadha A. Preparation of biodiesel fromcrude oil of Pongamia pinnata. BioresourTechnol 2005;96(13):1425e9.[7] Bora DK, Nath R. Use of Nahar oil methyl ester (NOME) in CI engines. J Sci Ind Res2007;6:256e8.[8] Chitra P, Venkatachalam P, Sampathrajan A. Optimisation of experimental conditions forbiodiesel production from alkali-catalysed transesterification of Jatropha curcus oil. Energy Sust Dev2005;9:13e8.[9] Ahmed WA, Salimon J. Phorbol ester as toxic constituents of tropical Jatropha curcas seed oil. EurJ Sci Res 2009;31(3):429e36.
    • International Journal of Advanced Research in Engineering and Technology (IJARET), ISSN0976 – 6480(Print), ISSN 0976 – 6499(Online) Volume 4, Issue 3, April (2013), © IAEME107[10] Darnoko D, Cheryan. Kinetics of palm oil transesterification in a batch reactor. J Am Oil ChemSoc 2000;77(12):1263e7.[11] Knothe G, Steidely KR. Kinematic viscosity of biodiesel fuel and related compound. Influence ofcompound structure and comparison to petrodiesel fuel component. Fuel 2005;84: 1059e65.[12] Knothe G, Bagby MO, Ryan TW. Precombustion of fatty acids and esters of biodiesel. Apossible explanation for differing cetane numbers. JAOCS 1998;75(8):1007e13.[13] RamadhasAS, Jayaraj S,MuraleedharanC.Biodieselproduction from high FFA rubber seed oil.Fuel 2005;84:335e40.[14] Cormick MC, Graboski RL, Alleman TL, Herring AM. Impact of biodiesel source materials andchemical structure onemissions of criteria pollutants from heavy e duty engine. Environ Sci Technol2011;35:1741e2.[15] Durrett TP, Benning C, Ohlrogge J. Plant triacylglycerols as feedstocks for the production ofbiofuels. Plant J 2008;54: 593e607.[16] Gunstone FD. Rapeseed and canola oil: production, processing, properties and uses. London:Blackwell Publishing Ltd; 2004.[17] Augustus GD, Jayablan M, Seiler GJ. Evaluation and bioinduction of energy components ofJatropha curcas. Biomass Bioenergy 2002;23:161e4.[18] Rao PV. Experimental investigations on the influence of properties of Jatropha biodiesel onperformance,combustion, and emission characteristics of a DI-CI engine. World Academy of Science,Engineering and Technology; 2011. p. 75.[19] Nourredini H, Teoh BC, Clements LD. Viscosities of vegetable oils and fattyacids. J Am OilChem Soc 1992;69:1184e8.[20] Monteiroa MR, Ambrozina ARP, Morais Liaob LM, Ferreira AG. Critical review on analyticalmethods for biodiesel characterization. Talanta 2008;77:593e605.[21] T. Pushparaj, S. Ramabalan, “Influence Of Cnsl Biodiesel With Ethanol Additive On DieselEngine Performance And Exhaust Emission” International Journal Of Mechanical Engineering &Technology (IJMET) Volume 3, Issue 2, 2012, pp. 665 - 674, ISSN PRINT : 0976 – 6340, ISSNONLINE : 0976 – 6359.[22] S.H. Choi, Y.T. Oh and J. Azjargal, “Lard Biodiesel Engine Performance and EmissionsCharacteristics With Egr Method” International Journal Of Mechanical Engineering & Technology(IJMET) Volume 3, Issue 2, 2012, pp. 397 - 409, ISSN PRINT: 0976 – 6340, ISSN ONLINE: 0976 –6359.