ABSTRACT
Studies of biodiesels from Thevetia peruviana (yellow oleander) seeds oil (YO) and Sus domesticus (pig lard) (PL) were carried out. Oil was extracted from YO and PL rendered from pig fat, which yielded 64.7% and 85.4% oil respectively. Some physicochemical parameters: flash points of 192oC and 165oC, calorific values of 13.79MJ/Kg and 12.02MJ/kg were obtained for YO and PL respectively. The FTIR analyses of the YO, PL and biodiesel showed the carbonyl functional group at 1739 cm-1 to 1745cm-1 as the most intense and prominent bands. The carbonyl (-C=O vibration) group of esters showed strong absorption bands at 1740cm-1 in the IR spectra of the biodiesels, indicating the presence of fatty acid methyl esters. The GC-MS analysis of the oils and biodiesels showed about 80% saturated/ monounsaturated fatty acids in both YO and PL, signifying high potential for biodiesel production. Biodiesels were prepared from the YO and PL using the base- catalyzed transesterification method. Biodiesel yields increased with increase in temperature and reaction time with minimal effect of catalyst concentration. The condition adjudged to be optimal for transeterification of YO and PL was at a temperature of 60oC, reaction time of 60 min and catalyst concentration of 1% w/w. Under this condition biodiesel yields were found to be 97.41% for yellow oleander methyl ester (YOME) and 95.12% for pig lard methyl ester (PLME) respectively. There was similarity in fatty acid composition in both YOME and PLME, with high oleic acid (57.84%), palmitic acid (15.56% to18.07%), stearic acid was in the range of 15.98% to 15. 65%, which placed them as better substitutes for fossil diesel. Fuel properties of blends (B10 to B50) of YOME and PLME with fossil diesel (FD) agreed with the ASTM specifications for biodiesels. The Kinematic viscosities of PLME-blends (from 3.76mm2/s in B10 to 4.84 mm2/s in B90) fall within the allowable limits of 3.5 – 5.0 mm2/s specified by ASTM D6751. The kinematic viscosities of YOME blends B60
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(5.04 mm2/s) and B90 (6.53 mm2/s) were above the ASTM limit. The specific gravity of the blended fuels of PLME-FD was not affected by the increasing biodiesel portion in the blend. All the blends show low cloud points above the ASTM limit of 4oC (except for B10 and B20 blends of YOME which are 3oC and 4oC respectively). At elevated temperatures of 100oC – 250oC specific gravities of all blends decreased while kinematic viscosity decreased with increase in treatment temperature. Long time storage of biodiesel fuels showed a steady increase in flash point, density, kinematic viscosity and acid value, with a decrease in peroxide and calorific value over the storage period of 120 days. As fraction of B100 increase in blends, the calorific value decreased by 1.10% in B20, 2.43% in B40 and 2.63% in B80 in YOME blends. Rate of decrease in calorific values also gets higher with storage time. Biodiesels from mixtures of YO and PL (ratio of 1:1, 1:2, and 2:1) gave high cloud point and low cetane numbers, however, their flash points, specific gravity and viscosity were all within the ASTM limits for biodiesel. Flash points of PL:YO (1:1) FAME and PL:YO (1:2) FAME were higher than that of FD (88oC). Biodiesel from yellow oleander seed oil was found to be a better substitute for conventional diesel than biodiesel from pig lard.
TABLE OF CONTENTS
Title Page i Declaration ii Dedication iii Certification iv Acknowledgement v Abstract vi Table of Content viii List of Figures xvi List of Tables xix List of Plates xxi List of Appendices xxii Abbreviations xxiv 1.0 INTRODUCTION 1 1.1 Renewable Energy 2 1.2 Statement of the Problem 3 1.3 Justification of the Research 5 1.4 Research Aim and Objectives 6 1.4.1 Aim 6
1.4.2 Objectives 7
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2.0 LITERATURE REVIEW 8 2.1 Triglycerides 8 2.2 Fatty Acid Composition of Some Oils 10 2.3 Biodiesel 11 2.4 Historical Development of Biodiesel 12 2.5 Biodiesel Feedstocks 13 2.5.1 Jatropha curcas 14 2.5.2 Yellow oleander 14 2.5.3 Lard 17 2.6 Methods of Oil Extraction 18 2.6.1 Traditional methods 19 2.6.2 Manual methods 19 2.6.3 Mechanised extraction 19 2.6.4 Solvent extraction method 20 2.6.5 Soxhlet extraction method 21 2.6.6 Ultrasonic-assisted extraction 21 2.7 Production of Biodiesel 22 2.7.1 Transesterification process 22 2.7.2 Base- catalysed transesterification 24 2.7.3 Acid- catalysed transesterification 26
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2.7.4 Two-step acid-base catalyzed transesterification 28 2.7.5 Transesterification using lipase- catalyst 29 2.7.6 Transesterification using heterogeneous catalyst 29 2.7.7 Non-catalytic conversion techniques 30 2.7.8 Non-ionic base- catalyzed processes 32 2.8 Factors Affecting Transesterification Process 33 2.8.1 Effects of moisture and free fatty acids 33 2.8.2 Effect of molar ratio of methanol to oil 33 2.8.3 Effect of catalyst type 34 2.8.4 Effect of catalyst concentration 35 2.8.5 Effect of reaction time 36 2.8.6 Effect of reaction temperature 37 2.8.7 Effect of agitation speed 37 2.9 Biodiesel Blends 38 2.10 Fuel Properties of Oils and Biodiesels 39 2.10.1 Cetane number 39 2.10.2 Acid value 41 2.10.3 Cold flow properties 42 2.10.4 Kinematic viscosity 43 2.10.5 Heat of combustion 44 2.10.6 Flash point 45 2.10.7 Specific gravity and density 45
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2.10.8 Iodine value 46 2.11 Oxidative Stability of Biodiesels 46 2.12 Gas Chromatography – Mass Spectrometry 48 3.0 MATERIALS AND METHODS 50 3.1 Chemicals 50 3.2 Sample Collection and Preparation 50 3.3 Pig Lard Preparation 51 3.4 Determination of Fatty Acid Composition 51 3.5 Transesterification of the Oils 52 3.5.1 Preparation of reagents 52 3.5.2 Base- catalysed transesterification of the yellow oleander seed oil and pig lard 53 3.5.3 Biodiesel blending 55 3.5.4 Temperature treatment of biodiesels 55 3.5.5 Storage of biodiesel 55 3.6 Determination of Physicochemical Properties of Yellow Oleander Seed Oil and Pig lard 56 3.6.1 Preparation of reagents 56 3.6.2 Determination of saponification value 56 3.6.3 Acid value determination of free fatty acid 57 3.6.4 Reduction of free fatty acid (%FFA) 58
3.6.5 Determination of specific gravity 58
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3.6.6 Determination of iodine value 59 3.6.7 Determination of refractive index 60 3.6.8 Determination of peroxide value 60 3.7 Determination of Fuel Properties 61 3.7.1 Determination of kinematic viscosity 61 3.7.2 Flash point determination 62 3.7.3 Cloud point analysis 62 3.7.4 Determination of pour point 63
3.7.6 Sulphur content determination 63
3.7.7 Test for cetane number 63
3.7.8 Calorific value determination 64
3.8 Fourier Transform Infrared Spectroscopy Analysis 64
4.0 RESULTS 66 4.1 Extraction and Physicochemical Properties of Yellow Oleander Seed Oil and Pig Lard 66 4.2 The Fuel Properties of Yellow Oleander Seed Oil and Pig Lard 66 4.3 Fatty Acid Profile of Yellow Oleander Seed Oil and Pig Lard 69 4.4 FTIR Spectra of Yellow Oleander Seed Oil and Pig Lard 69 4.5 Effect of Variation of Reaction Time, Temperature and Catalyst Concentration on Yellow Oleander Methyl Ester and Pig Lard Methyl Ester Yield 78 4.6 FTIR Analysis of Yellow Oleander Methyl Ester and Pig Lard Methyl Ester 87
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4.7 Fatty Acid Compositions of Yellow Oleander Methyl Ester and Pig Lard Methyl Ester 93 4.8 Fuel Properties of Yellow Oleander Methyl Ester and Pig Lard Methyl Ester in Comparison with FD 101 4.9 Effects of Blending on Biodiesel Properties 101 4.10 Correlation Coefficient Analysis of Blends from Yellow Oleander Methyl Ester and Pig Lard Methyl Ester 112 4.11 Effect of Temperature on Kinematic Viscosity, Acid Value and Peroxide Value of Biodiesels 115 4.12 Effect of Storage Period on Methyl Ester and Methyl Ester Blends 119 4.13 Effect of Elevated Temperatures on the Properties of Methyl Ester Blends 127 4.14 Biodiesel from Mixed Yellow Oleander Seed Oil and Pig Lard 137 4.14.1 Properties of FAMEs of mixed yellow oleander seed oil and pig lard 137 4.14.2 Effect of elevated temperature on biodiesels from mixed yellow oleander seed oil and pig lard 137 5.0 DISCUSSION 143 5.1 Oil Yield of Yellow Oleander Seed Oil and Pig Lard 143 5.2 Physicochemical Properties of Yellow Oleander Seed Oil and Pig Lard 143 5.2.1 Specific gravity and density 143 5.2.2 Acid value 144 5.2.3 Peroxide value 145 5.2.4 Saponification value 145 5.2.5 Iodine value 146 5.2.6 Refractive index 146 5.2.7 Kinematic viscosity 147
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5.2.8 The calorific value 147 5.3 The FTIR Spectra Peaks of Yellow Oleander Seed Oil, Pig Lard, Yellow Oleander Methyl Ester and Pig Lard Methyl Ester 148 5.4 Biodiesel Production from Yellow Oleander Seed Oil and Pig Lard 149 5. 4.1 Effect of variation of reaction time on biodiesel yield 149
5.4.2 Effect of reaction temperature on biodiesel yield 149
5.4.3 Effect of catalyst concentration on biodiesel yield 150 5.5 Fatty Acid Profile of Yellow Oleander Seed Oil, Pig Lard, Yellow Oleander Methyl Ester and Pig Lard Methyl Ester 150 5.6 Comparison of Fuel Properties of Biodiesels of Yellow Oleander Seed Oil and Pig Lard 152 5.6.1 Specific gravity 152 5.6.2 Flash point 152 5.6.3 Cloud point 152 5.6.4 Acid number 153 5.6.5 Kinematic viscosity 153 5.6.6 Cetane number 154 5.6.7 Sulphur content in the fatty acid methyl esters 154 5.7 Effect of Blending on Biodiesel Properties 155 5.8 Effect of Elevated Temperatures on Biodiesel Properties 157 5.9 Effect of Storage Period on Properties of Biodiesel Blends 159 5.10 Effect of Elevated Temperatures on Biodiesel Blends 162
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5.11 Fuel Properties of Biodiesels Obtained from Mixed Yellow Oleander Seed Oil and Pig Lard 163 5.12 Effect of Temperature on Fuel Properties of Biodiesels Derived from mixtures of Yellow Oleander Seed Oil and Pig Lard 163 6.0 SUMMARY, CONCLUSION AND RECOMMENDATION 165 6.1 Summary 165 6.2 Conclusion 167 6.3 Recommendations 168 REFERENCES 170 APPENDICES 192
CHAPTER ONE
1.0 INTRODUCTION
The world‘s population has relied heavily on fossil fuels for energy generation and transportation for over two centuries (Devanesan et al., 2007). The rapid growth of the world‘s population over the past one hundred years and rapid industrialisation among nations have resulted in high energy demand in the industries as well as in the domestic sector. This has led to increase in the depletion of petroleum products and pollution problems due to the widespread use of fossil fuels. Hence, the world‘s reserves of fossil fuels are continually being depleted and new discoveries are smaller with lower quality (Munack et al., 2001; Agbo and Oparaku, 2006). Energy demand is growing and has been projected to increase by more than 50% in 2025 (Adams, 2002), with much of this increase in demand emerging from several rapidly developing nations like Nigeria. Fossil fuels are non-renewable and once consumed cannot be replenished. This is pointing to the fact that the supply may well run out one day. The depletion of world petroleum reserves and increased environmental concerns have led to increase in energy insecurity and hence stimulated the search for alternative renewable fuels that are capable of fulfilling an increasing energy demand.
Going by the present rate of global fossil fuel consumption, crude oil reserves could be depleted in less than the next 50 years (Devanesan et al., 2007). It has been widely reported that not less than ten major oil fields from the 20 largest world oil producers are already experiencing decline in oil reserves (Alamu et al., 2007a). According to the U.S. Energy Information Administration, the global supply of crude oil, other liquid hydrocarbons, and biodiesels are expected to be adequate to meet the world’s demand for liquid fuels for at least the next 25 years.
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There is substantial uncertainty about the levels of future fossil fuels supply and demand, a clear indication that in some few years to come these oil reserves will be expended (EIA, 2014). This has stimulated interest in alternative sources for fossil fuels. An alternative fuel must be technically feasible, sustainable, economically acceptable and readily available (Meher et al., 2006). Biodiesel is therefore gaining attention worldwide as an alternative automobile fuel. An important factor in the search for alternative sources of fuel is the concern over greenhouse gas emission from fossil fuels. Fossil fuels such as petroleum, coal and natural gas, which have been used to meet the energy needs of man, are associated with negative environmental impacts such as global warming resulting from green house gases (Munack et al., 2001; Saravanan et al., 2007). These emissions such as CO2, CO, NO2, NO, SO2 and SO3 are responsible for some of the major environmental problems of urban and industrial areas and their surroundings by depleting the ozone layer and causing global warming (Turner, 2005). Also, the environmental concerns regarding greenhouse gas emissions and commitment of the International Community to significantly reduce emissions as formalised by the Kyoto Protocol (UNFCCC, 1998) adopted in December, 1997 triggered the need to find more sustainable alternatives to fossil fuels. 1.1 Renewable Energy
Biodiesel consists of the simple alkyl esters of fatty acids and is oxygenated, sulphur free, biodegradable, non-toxic and environmentally friendly alternative automotive fuel. It can be produced from renewable sources such as vegetable oils, animal fats, restaurant waste oil and frying oil. Its use does not require any major modification in the existing diesel engine. Biodiesel has been reported (Batidzirai et al., 2012) to be a promising long-term renewable energy source which has potential to address both environmental impacts and security concerns posed by
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current dependence on fossil fuels. The advantages of bio-fuel over the conventional diesel fuel include low smoke and particulates, low carbon monoxide and hydrocarbon emissions; improved biodegradability, reduced toxicity and higher cetane number which can improve engine performance and clean emission (Encinar et al., 2007). A typical biodiesel produces about 65% less net carbon monoxide, 78% less carbon dioxide, 90% less sulphur dioxide and 50% less unburnt hydrocarbon emission (Knothe and Steidley, 2005). The major constraint in the wide spread use of biodiesel is the production cost which includes the costs of raw materials and the process operation. The feedstocks for biodiesels are also used for food, making their prices high and may even get higher in future (USDA, 2008), hence the main hurdle to its commercialization. The cost of raw materials represents approximately 60- 75% of the total cost of biodiesel production (Jeong et al., 2009; Ma and Hanna, 1999). As a future prospective, biodiesel has to compete economically with petroleum diesel fuels. One way of reducing the biodiesel production cost is to use the less expensive/low cost feed stock containing fatty acids such as animal fats, inedible oils, restaurant waste oil, frying oil, products of refining of vegetable oil instead of edible vegetable oil which could lead to food crisis (Veljkovic et al., 2006; Cankci et al., 2001; Mittelbatch et al., 1992). These low cost feed stocks are more challenging to process because they contain high amount of free fatty acids (FFA) but could be overcome by improving on the production process through the use of two stage transesterification processes at optimum reaction conditions for maximum biodiesel yield (Kombe et al. 2013). 1.2 Statement of the Problem
Fossil fuel is non-biodegradable; therefore, its usage for energy generation has attracted global concern in recent times, because of its high emission of green house gases during
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combustion. These emissions are the principal causes of environmental degradation, global warming and green house effects (Bells and Davis, 2006), ozone layer depletion and some incurable diseases across the globe (UCS, 2002). The fossil fuels take million of years to form and are depleting without an immediate replacement (IEA, 2009). The ever-increasing competing demand for energy sources, coupled with the fact that fossil fuel is non-renewable, has led to the prediction that world‘s reserves of fossil fuel would be expended before the end of the 21st century (Shahriar and Erkan, 2009). Petroleum crises, which includes uncertainties concerning petroleum fuels availability, environment issues due to increase in Green House Gas (GHG) emission, ozone layer depletion and increasing concern over global warming pose a great risk. Also the high production cost of biodiesel emanating mainly from the feed stock and the use of edible oils could lead to food crisis. All these contending issues are worldwide concerns and have led to the global shift in reliance on fossil fuel to more environmentally friendly and sustainable source of energy in order to fulfill an increasing energy demand. It has become also imperative to direct focus on mitigating the production cost which is primarily due to the cost of raw material by the use of low cost feed stock (animal fat) and determination of the optimum reaction conditions at which increase in the yield of the methyl ester (biodiesel) could be achieved in order to supplement the conventional petrol diesel. Research in this area has been centred on discovering and improving feedstock for biodiesel production. Several articles have been published with the aim of improving on the yield and fuel properties of biodiesel produced from different vegetable oils (Odeigah et al., 2012; Knothe et al., 2009; Knothe, 2008; Voca et al., 2008).
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1.3 Justification of the Research Nigeria depends on imports for its supply in fossil fuels and for the past few years it has faced a crisis of oil supply and unpredictable prices. Use of fossil fuels leads to increase in greenhouse gases (SO2, NO2, CO2 etc.) that lead to destruction of ozone layer and contribute to climate change. These problems provide adequate reasons and incentives to focus on renewable energy alternatives to fossil fuels. Nigeria ought to diversify its energy supply sources by developing alternative renewable sources of energy from non-edible oils to mitigate the impact of fossil fuel on its economy and the environment. Biodiesel, among the alternative sources of energy, appears to offer the best opportunities. Biodiesel production from conventional sources such as soybean, rapeseed, sunflower and palm oil, has increasingly placed strain on food production, price and availability. High cost of edible vegetable oils is a major challenge for economic viability of biodiesel industries and can hardly be afforded by poor and underdeveloped countries. It is therefore inevitable to look for non-edible but economically viable feedstocks as an alternative to edible vegetable oils.
Several feedstocks such as karanja (Pongamia glabra) (Raheman and Phadatare, 2004, Sarma et al., 2005), field pennycress (Thlaspi arvense L.) (Moser et al., 2009), rubber (Hevea brasiliensis) (Ramadhas et al., 2005), Jatropha curcas (Shah et al.,2004; Prueksakorn and Gheewala, 2008), microalgae (Chlorella vulgaris) (Scragg et al., 2003), terminalia (Terminalia belerica Robx.) (Chakraborty et al., 2009), mahua (Madhuca indica) (Puhan et al., 2005 and Raheman and Ghadge, 2007) and others are already under consideration by the world community. In Nigeria, the preferred oils for biodiesel production are the non-edible oils in appreciable quantity. Some recent studies show the utilization of non-edible oils for biodiesel
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production from Jatropha curcas L. (Liu et al., 2012) and neem seed oils (Aransiola et al., 2012). Oluwaniyi and Ibiyemi (2007) reported the high oil yield of Thevetia peruviana seed, which could be an excellent feedstock for the biodiesel industry. Lard is prohibited by dietary law that forbids the consumption of pork, such as ‗kashrut’ and ‗halal’. Some religions like Islam, Judaism and Hinduism do not allow their followers to consume any foods containing lard in its formulation (Regenstein et al., 2003). Where the pig flesh is being processed and isolated for commercial purpose, the fatty tissues are less valued and can be obtained from the butchers at a give away price. The diminishing use of lard as food in northern Nigeria has rendered it available as feedstock for production of biodiesel in Nigeria. The utilisation of Thevetia peruviana (yellow oleander) seed oil and Sus domesticus (pig) lard as renewable raw materials for biodiesel production in Nigeria will not affect food security. It will reduce biodiesel production cost and ensure its sustainability and availability. It will also give rise to availability of alternative fuel that meets ASTM standard which is renewable, environmentally friendly and affordable, hence mitigating green house effect and redeeming our climate. 1.4 Research Aim and Objectives 1.4.1 Aim The aim of this work is to continue the search for sustainable renewable feedstock in biodiesel production in Nigeria by assessing the viability of using a less popular non-edible seed oil- Thevetia peruviana and animal fat- Sus domesticus for biodiesel production and to evaluate their quality as compared to ASTM standards.
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1.4.2 Objectives :
i. To determine the oil content of Thevetia peruviana (yellow oleander seeds) and Sus domesticus (pig lard);
ii. To determine the physicochemical and fuel properties of yellow oleander seed oil and pig lard;
iii. To determine the fatty acid composition of the yellow oleander (Thevetia peruviana) seed oil and the pig (Sus domesticus) lard and of their methyl esters;
iv. To determine the functional groups in the yellow oleander (Thevetia peruviana) seed oil and the pig (Sus domesticus) lard and in their methyl esters (YOME and PLME);
v. To study the effect of process variables (such as reaction temperature, time and KOH catalyst loading) in the transesterification process for biodiesel production of yellow oleander methyl ester and pig lard methyl ester using methanol and the production of biodiesel from the mixtures of the oils at optimum conditions;
vi. To determine the physicochemical and fuel properties of the YOME, PLME, their blends and biodiesels of the mixed oils at room temperature and compare with ASTM standards;
vii. To investigate the effect of high temperature and storage period on the stability and shelf-life of YOME, PLME and their blends.
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