ABSTRACT
Renewable oils from biomaterials are now acknowledged as having the potential to provide for alternative fuels (biodiesel) and interest in the use of biofuels worldwide has grown strongly in recent years due to the limited oil reserves, concerns about climate change from greenhouse gas emissions and the desire to promote domestic rural economies. At present, biodiesel is mainly produced from conventionally grown edible oils such as soybean, rapeseed, sunflower, and palm. On the other hand, extensive use of edible oils for biodiesel production may lead to food crisis. The cost of biodiesel is the main obstacle to commercialization of the product. Biodiesel produced from edible oils is currently not economically feasible which calls for more exploration for under utilized edible seeds the African oil bean seed. This work is on the effect of pre-treatment method technique (drying) on oil recovery from oil bean seeds (Pentaclethra macrophylla Benth) for biodiesel production which was investigated. Samples were drawn from the different stages during the treatment (namely; oven dry at 500C, 600C and 700C at an hour interval, solar drying and Open sun drying). Solvent extraction process using normal hexane was used to extract oil from the various product and there physiochemical properties: saponification value, Peroxide value, Acid value , Iodine value , Specific gravity, color were analyzed and compared to CODEX standard. The oil was further used in acid-catalyzed esterification and alkaline transeterification for biodiesel production and the effects of temperature, catalyst concentration,feedstock to methanol molar ratio, and reaction time on biodiesel conversion were investigated. By using a feedstock to methanol molar ratio of 1:6 and a sulfuric acid concentration of 0.8%, a biodiesel conversion of 81% was obtained after 6 h of reaction at 500C. The biodiesel produced by this process met the American Society for Testing and Materials (ASTM) standard
TABLE OF CONTENTS
Title Page i
Declaration ii
Certification iii
Dedication iv
Acknowledgements v
Table of Contents vi
List of Tables xi
List of Figures xii
Abstract xiii
CHAPTER 1: INTRODUCTION 1
1.1 Background of the Study 1
1.2 Problem Statement 2
1.3 Objectives of the Study 2
1.4 Justification 3
1.5 Scope of the Study 4
CHAPTER 2: LITERATURE REVIEW
2.1 Drying 5
2.2 Drying Methods 6
2.2.1 Sun drying 6
2.2.2 Solar drying 6
2.2.3 Freeze drying 7
2.2.4 Oven drying 7
2.2.5 Refractance window drying 7
2.3 Feedstock Used in Biodiesel Production 8
2.4 Properties of Biodiesel 9
2.4.1 Kinematic viscosity 11
2.4.2 Cetane number 11
2.4.3 Flash point 12
2.4.4 Heating value 12
2.4.5 Lubricity 12
2.4.6 Oxidative stability 13
2.4.7 Cold flow properties 13
2.4.8 Iodine value (IV) 15
2.5 Oil Seeds Used as Feed Stock for Bio Diesel Production 15
2.5.1 Water-melon (citrullus vulgaris) 16
2.5.1.1 Physio-chemical properties of watermelon seed oil 17
2.5.2 Soyabean (glycine max) 18
2.5.2.1 Physio-chemical properties of soyabean seed oil 19
2.6 Extraction Methods of Oil from Various Oil Seeds 20
2.6.1 Mechanical extraction 21
2.6.2 Solvent extraction (chemical extraction) 23
2.6.3 Enzymatic oil extraction 23
2.7 Physio-Chemical Properties 26
2.7.1 Viscosity 26
2.7.2 Refractive index 26
2.7.3 Acid values 26
2.7.4 Specific gravity 26
2.7.5 Saponification 26
2.7.6 Iodine values 27
2.7.7 Peroxide values 27
2.7.8 Yield 27
2.8 Proximate Composition 27
2.8.1 Moisture content 27
2.8.2 Volatile matter 28
2.8.3 Ash content 28
2.8.4 Fixed carbon 28
2.9 Technologies of Biodiesel Production from Oils 29
2.9.1 Transesterification or alcoholysis 29
2.9.2 Biodiesel production process 32
2.9.3 Stages of biodiesel production process 33
2.9.3.1 Treatment of raw materials 33
2.9.3.2 Alcohol-catalyst mixing 33
2.9.3.3 Chemical reaction 34
2.9.3.4 Separation of the reaction product 34
2.9.3.5 Purification of the reaction products 34
2.9.4 Factors affecting the production of biodiesel 35
2.9.4.1 Effect of molar ratio of alcohol 35
2.9.4.2 Effect of water and FFA contents 36
2.9.4.3 Reaction time 37
2.9.4.4 Reaction temperature 37
2.9.4.5 Catalyst concentration 37
2.9.4.6 Agitation speed 38
CHAPTER 3: METHODOLOGY
3.1 Materials 39
3.1.1 Reagents 39
3.1.2 Apparatus 40
3.2 Methods 41
3.2.1 Seed preparation 41
3.2.2 Oil extraction 43
3.2.3 Pretreatment of the extracted oil from the African oil bean seed
degumming process 45
3.2.4 Acid pretreatment: acid catalyzed esterification 45
3.2.5 Alkaline transesterification 45
3.2.6 Separation of glycerin from the biodiesel 47
3.3 Characterization of biodiesel 49
3.3.1 Determination of acid value (AV): 49
3.3.2 Determination of saponification number (SN): 50
3.3.3 Determination of iodine value (IV) 51
3.3.4 Moisture content determination 51
3.3.5 Determination of specific gravity (SG): 52
3.3.6 Determination of peroxide value: 52
3.3.7 Determination of heating value (calorific value): 53
3.3.8 Determination of cetane number (CN), astm d613 53
3.3.9 Determination of flash point, astm d93: 53
3.3.10 Cloud point 53
3.3.11 Pour point 54
CHAPTER 4: RESULT AND DISCUSSION
4.1 Physiochemical Properties of Oil Extracted 55
4.2 Characterization of African Oil Bean Biodiesel 58
4.3 Biodiesel Production and Process Effects 61
CHAPTER 5: CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 64
5.2 Recommendation 65
References
Appendix
LIST OF TABLES
2.1: ASTM D6751 Biodiesel (B100) specifications (Denver, 2006) 10
2.2: Low temperature performance tests for biodiesel. 14
2.3: Average value of physcio-chemical properties of watermelon seed oil. 17
2.4: Average value of physcio-chemical properties of soyabean seed oil. 19
2.5: Calculated oil yields (% of contained oil) of mechanical extraction Methods 22
2.6: Reported oil yields for different chemical and enzymatic extraction methods and different reaction parameters 56
4.1 Physiochemical properties of oil extract from African oil bean seed 59
4.2 Characterization of bio diesel 62
4.3 Biodiesel production and process effects 64
LIST OF FIGURES
2.1: Transesterification reaction of triglycerides 21
2.2: Process flowchart of non-edible crops seed to biodiesel 21
3.1 African oil beans seed 31
3.2 Dehulled African oil bean seed 31
3.3 Soxhlet Apparatus 32
3.4 Trans-esterification set up 34
3.5 Separation of biodiesel and glycerol using a separatory funnel
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE STUDY
The African oil bean seed (pentaclethra macrophylla Benth) is a legume with no known variation characterization (Keay, 1989). Majorly found in the Southern and Eastern regions of Nigeria. It develops to a height of approximately 21 m in height and 6 m in girth forming a branched canopy. It brings forth flowers between March and April, there after the pods (brown and woody at maturity) open by means of explosive mechanism, there by dispersing the seeds and curls up. The seeds are dorsa-ventrally flattered, hard, brown in color and about 6 cm long and 3 cm wide (Achinewhu et al., 1998).African oil bean seed are obtained locally from the wild and has been found to contain 27 to 40% edible oil.
The African oil bean seed can be categorized as an under-utilized crop because locally its uses is channeled mainly for consumption purposes only for the seeds. Value addition to the product like oil extraction and conversion of oil to other products that can yield higher financial turnover is neglected. However with its high oil yielding potential it can be adopted in producing bio-oil and biodiesel with its potential of solving technological problems in the area of renewable energy production. Biodiesel is considered as an immediate alternative to conventional fossil based energy, with environmental impact of decreasing the effects of harmful global greenhouse gases also causing a fall in the reliance on fossil fuel (Demirbas, 2008). In literature similar seeds have been used for production of lubrication oil and have been found to be biodegradable and non-toxic (Thames and Yu 1999). Various researches have been carried out on physio-chemical properties and biodiesel characterization of vegetables seed oils in addition to physical characteristics of seeds. Gabriel et al (2014) studied bio-diesel production with seed soybean and supercritical ethanol by a non-catalytic process. The non-catalytic trans-esterification with an alcohol in super critical circumstances has been emphasized as an alternative technique for bio-diesel production (Demirbas, 2003).
Bio-diesel from palm oil has important prospective as an alternative source of fuel in compression ignition (CI) engine (Rafsan 2016). Palm oil is converted into ester through trans-esterification method and performance test carried out with diesel in compression internal engines. Wei-Jia et al (2008) studied the acid catalyzed/enzymatic hybrid procedure for the production of bio-diesel using soybean oil as feedstock. In this process the oil underwent hydrolysis by binary immobilized lipase after 5 hours in optimal conditions.
The above studied oil seeds has similar oil characteristics like oil bean seed but little or no research has been carried out to study its bio-oil and biodiesel potential. Locally it seems oil bean seed have little or no relevance in industrial sector except in local preparation for consumption for local delicacies hence studies that will add value to the product has become necessary. Again oil recovery from biomaterials involves initial operations, such as shelling, cleaning, drying and milling. Generally, the overall quantity of recovered oil depends mainly on the duration of the extraction period, product moisture content, temperature and the structure of oil-bearing cells. However, moisture content reduction and the preservation of the oil-bearing cells is a function of the drying techniques. Therefore there it is essential to investigate drying techniques on drying oil bearing biomaterials to test their efficacy in improving oil extraction rate and quality for crops like oil bean seed.
1.2 PROBLEM STATEMENT
Climatic change a global situation is on the rise due to the effects and hazards of fossil fuel (global warming). The search for renewable energy resources which is biodegradable and safe for human health is on the increase. The seed of African oil bean with high oil yield currently is underutilized with little or less cultivation processes. Farmers are not getting good value from it because it is only serves for local delicacies with little or no known industrial application. This seed with its high oil yield can serve as a feedstock in bio-oil and biodiesel production for higher financial turnover.
1.3 OBJECTIVES OF THE STUDY
The main objectives of the study will be the investigation of the effects of heat treatment method, as a pretreatment operation to oil recovery, extraction yields and quality features from the seeds of oil bean. However, the research specific objective will include:
i. Extraction and quantification of bio-oil from different drying treatments
ii. Evaluate the physic-chemical properties of the bio-oil produced by different drying treatment.
iii. Bio-diesel production from the best bio-oil
iv. Characterization of bio-diesel produced.
1.4 JUSTIFICATION
Oil recovery from biomaterials involves initial operations, such as shelling, cleaning, drying and milling. Convective drying stands as the most commonly used method of drying to reduce moisture from vegetables, fruits and medicinal plants. In convective drying biomaterials are dried with heat supplied at an air flow rate in an enclosed chamber over a period time. Generally, the overall quantity of recovered oil depends mainly on the duration of the extraction period, product moisture content, temperature and the structure of oil-bearing cells. However, moisture content reduction and the preservation of the oil-bearing cells is a function of the drying techniques. Therefore there it is essential to investigate other novel drying techniques on drying oil bearing biomaterials to test their efficacy in improving oil extraction rate and quality. The introduction and the use of hybrid drying techniques are essential to overcome the disadvantages of orthodox methods of drying while putting into consideration the sensitivity of bioactive components in medicinal herbs to thermal oxidation and degradation. Combined methods of drying are observed as more flexible since the benefits of two or more methods of drying may proffer superior drying results than an single approach (Chan et al. ,2015)
1.5 SCOPE OF THE STUDY
The scope of this study will be limited to sun drying, solar drying and convective oven drying methods.
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