TABLE OF CONTENTS
Title Page……………………………………………………………………………i.
Certification Page…………………………….……………………………………..ii.
Dedication……………………………………………………………………….….iii.
Acknowledgement…………………………………………………………………..iv.
Abstract………………………………………………………………………………v.
Table of contents………………………………………………………………..……vi.
List of Tables……………………………………………………………………..…ix.
List of graphs………………………………………………………………..……….x
List of Figures……………………………………………………………………….x
List of Abbreviations………………………………………………………………..xi
CHAPTER ONE: INTRODUCTION………………………………………………1.
1.1. Avocado fruit…………………………………..………………………..………27.
1.1.1 Cultivars and Varieties………………………..……………………………….36.
1.1.2. Taxonomy of Avocado……………………………………………………….30.
1.1.3. Description of the avocado fruit pulp oil…………………………………….31
1.2. Biodiesel and other fuels………………………………………………………31.
1.2. Biodiesel production…………………………………………………………………..32.
1.2.1. Transesterification process……………………………………………………33.
1.2.2. Catalysts for biodiesel production………………………………..……………36.
1.2.3. Types of Biofuels……………………………………………………………37.
1.2.4. Alcohols used in biodiesel production………………………………………..39.
1.2.5 Biodiesel standard fuel properties………….….………….………………….40
1.2.6 Uses of biodiesel co-product: glycerol………………..………………………42
1.6. Aim and Specific Objectives of the Study………………………………………42
1.6.1. Aim of the Study………………………………………………………………42
1.6.2. Specific Research Objectives……..……………..……………………………42
CHAPTER TWO: MATERIALS AND METHODS
2.1. Materials………………….………………………………..…………………….44
2.1.1. Instruments/Equipment………….………………………….………………….44
2.1.2. Chemicals…………………………………….…………………………….…45
2.1.3. Samples……………………………………….………..……………………..46
2.2. Methods…………………………………….…………………………………..46
2.2.1. Preparation of reagents……………….……………………………..……….46
2.2.2. Preparation of avocado fruit for oil extraction…….……..…………………..47
2.2.3. Extraction of the avocado pulp oil………..…….…..…………………..……47
2.2.4. Characterization of the samples…………………..………………….….……..48
2.2.4.1. Determination of the Physical properties of the samples……….…….48
2.2.4.2.Determination of Chemical properties ………………………………………54.
2.2.5.5 Production of biodiesel from the avocado pulp oil……………58
CHAPTER THREE: RESULTS
3.1. Estimation of percentage yield of avocado pulp oil (APO)……..60
3.2. Characterization of avocado pulp oil (APO)………………………………60
3.2.1. Physical properties …………………………………………………………..60
3.2.2. Chemical properties……………………………………………………………61
3.3. Gas chromatography analysis of APO………………….……………………….63
3.4. The APO biodiesel production……………………….……………………….64
3.5. Characterization of the APO biodiesels…………………………………………64.
3.5.1. Physical properties…………………………………………………………65
3.5.2. Chemical properties…………………………………………………………….65
3.6. Gas chromatography analysis of methyl ester…………….…………………….66
3.7. Gas chromatography analysis of ethyl ester……………………………………..67
3.8. Comparative analysis of the fuel properties……………………………………70
CHAPTER FOUR: DISCUSSION
4.1. Discussion………………………………………………………………………72
4.2 Conclusion……………………………………………………………………
REFERENCES……………………………………………….………………….….80
LIST OF TABLES
Table 1: Average weight percentage (%) yield of avocado pulp oil….…58.
Table 2: Physical properties of the avocado pulp oil (APO) in average values….59.
Table 3: Chemical properties of the APO in average values………….………….60.
Table 4: Components of the avocado pulp oil analysed…………………………61.
Table 5: Average percentage (%) yield of the methyl and ethyl esters………….63.
Table 6: Physical properties of the methyl and ethyl esters……………………..64.
Table 7: Chemical properties of the methyl and ethyl esters……………………65.
Table 8: Components of the APO methyl esters………………………………..66.
Table 9: Components of the APO ethyl esters………………………………….67.
Table 10: Comparison of fuel properties of the APO methyl and ethyl
esters with petrodiesel and biodiesel standards………………………………………………70.
LIST OF FIGURES
Figure 1: Pictorial view of avocado fruit………………………………….29.
Figure 2: Biodiesel processing flow diagram…………………………….33.
Figure 3: Transesterification of TAG to yield FAAE…………………….35.
Figure 4: Saponification taking place as a side reaction when a basic
catalyst is used for feedstocks high in FFA………………………………37.
Figure5: Hydrolysis of biodiesel to yield FFA and methanol…….……….37.
Figure6: Chromatogram of avocado pulp’s oil (APO)……………..……..62.
Figure 7: Chromatogram of the methyl ester………………………….….68.
Figure 8: Chromatogram of the ethyl ester… .…………..…..69.                            Â
CHAPTER ONE
INTRODUCTION
There is a need for alternative energy sources to petroleum-based fuels due to the depletion of the worlds’ petroleum reserves,global warming and environmental concerns. American standard testing and materials defined biodiesel as a fuel composed of monoalkyl esters of long-chain fatty acids derived from renewable vegetable oils or animal fats and meets the requirements of ASTM 6751(ASTM, 2008). Ozone depletion,global warming,greenhouse gases concerns have promoted biodiesel as an alternative renewable and eco-friendly fuel.The concept of biofuel is notnew. Rudolph Diesel was the first to use a vegetable oil(peanut oil) in a diesel engine in 1911(Akoh et al ., 2007 ; Antczak et al., 2009). The use of biofuels in place of conventional fuels would slow the progression of global warming by reducing sulphur,carbon oxides and hydrocarbon emissions (Fjerbaek et al., 2009). Because of its high viscosity and low volatility, the direct use of vegetable oil in diesel engines can cause problems including;high carbon deposits,scuffing of engine liner,injection nozzle failure,gum formation,lubricating oil thickening,high cloud and pour point (Fukuda et al., 2001; Murugesan et al.,2009). In order to avoid these problems, the feedstock is chemically modified to its derivatives which have properties more similar to conventional diesel (Fukuda et al., 2001).Transesterification is the process by which biodiesel is produced,in this process vegetable oil reacts with an alcohol(methanol) to form methyl ester (biodiesel) and another alcohol (glycerol) with NaOH as catalyst (Pinto et al., 2005). Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
In 2010, worldwide biofuel production reached 105 billion liters (28 billion gallons US), up 17% from 2009, and biofuels provided 2.7% of the world’s fuels for road transport, a contribution largely made up of ethanol and biodiesel. Global ethanol fuel production reached 86 billion liters (23 billion gallons US) in 2010, with the United States and Brazil as the world’s top producers, accounting together for 90% of global production. The world’s largest biodiesel producer is the European Union, accounting for 53% of all biodiesel production in 2010. As of 2011, mandates for blending biofuels exist in 31 countries at the national level and in 29 states or provinces. The International Energy Agency has a goal for biofuels to meet more than a quarter of world demand for transportation fuels by 2050 to reduce dependence on petroleum and coal.There are various social, economic, environmental and technical issues relating to biofuels production and use, which have been debated in the popular media and scientific journals. These include: the effect of moderating oil prices the “food vs fuel debate, poverty reduction potential, carbon emissions levels, sustainable biofuel production, deforestation and soil erosion loss of biodiversity and impact on water resources (Mc Carthy et al., 2011).
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuelconsisting of long-chain alkyl (methyl, ethyl, or propyl) esters. Biodiesel is typically made by chemically reacting lipids(e.g., vegetable oil, animal fat (tallow) with an alcohol producing fatty acid esters (Fletcher et al., 2011). Biodiesel is meant to be used in standard diesel engines and is thus distinct from the vegetable and waste oils used to fuel converted diesel engines. Biodiesel can be used alone, or blended with petrodiesel in any proportions. Biodiesel can also be used as a low carbon alternative to heating oil (Monyem and Van Gerpen, 2001).
