OPTIMIZATION OF BIODIESEL FROM COCONUT (Cocos nucifera) SEED OIL
Coconut seeds was investigated for its use as biodiesel feedstock. Oil was extracted from coconut seeds using soxhlet extraction method where 67.2% yield of oil was obtained. Biodiesel synthesis was developed and optimized using Box-Behnken design in Response Surface Methodology to study the effect of experimental variables such as methanol to oil ratio, catalyst concentration, reaction temperature and reaction time on the extracted oil from coconut seeds. The model shows optimum conditions of biodiesel yield of 79% were found at 6:1 alcohol/oil ratio, 1% catalyst concentration (KOH), reaction temperature of 650C and reaction time of 40 min. respectively. At the end of experimental design it was found that the catalyst concentration and reaction time significantly affect the biodiesel yield than the molar ratio among others under the range of values studied. The produced biodiesel was analyzed for its physicochemical and characterized for its fatty acid methyl ester (FAME) profile using GC-MS. The fuel properties of biodiesel obtained showed that except cetane number, diesel index and sulphur content that were higher than the recommended ASTM values all other determined properties were within the ASTM specification indicating that its quite suitable as an alternative source of fuel.
TABLE OF CONTENTS
Table of Contents… v-vi
List of Tables… vii
List of Figures… viii
Introduction and Literature Review 1
Vegetable Oils 3
Literature Review 4
Coconut (Cocos-Nucifera) 4
Biodiesel Production 5
Factors Affecting Biodiesel Production 8
Fuel Properties of Biodiesel 12
Environmental Consideration on use of Biodiesel 15
By-products of Biodiesel 16
Aim and Objectives 17
Scope of Work 18
Justification of study 18
Materials and Methods 20
Apparatus/Instrument and Reagents 20
Preparation of Reagents 20
2.2.1 Sampling 21
2..2.3 Sample Preparation 21
Oil Extraction 21
Determination of Percentage Yield 22
Determination of Moisture Content 22
Determination of Acid Value 23
Determination of Saponification Value 23
Determination of Ester Value 24
Determination of Iodine Value 25
Transesterification of Oil 25
Determination of Fatty Acid Methyl Ester (Fame) of Coconut Oil Using Gas Chromatography (GC-MS) Method 26
Fuel Properties of Biodiesel (COME) 27
Experimental Optimization of Biodiesel 31
Results and Discussion 33
Conclusion and Recommendations 44
INTRODUCTION AND LITERATURE REVIEW
The replacement of mineral fuel by biodiesel is one of the effective ways of solving the problem of saving and effective usage of energetic resources. Biodiesel is becoming an increasingly acceptable alternative to fossil diesel because of narrowing gap between worldwide oil production and consumption. Also Nigeria’s vegetation and rainfall regime support agrarian activities that can produce feedstock for biofuel production. Sustainable biofuel production will create more jobs and stimulate related industries thus improving the socio- economic industries of the country (Itodo et al., 2010).
The surge of interest in biodiesel has highlighted a number of positive environmental effects associated with its use. These potentialities include reduction in greenhouse gas emission, deforestation, pollution and the rate of biodegradation (US department of energy, 2003).
Biodiesel is a non-petroleum based fuel made from virgin or used vegetable oil (both edible and non-edible) and animal fat. The main sources or biodiesel can be non-edible oils obtained from plants species available in different countries. Direct application of vegetable oils as fuel for diesel engine is not possible due to its higher viscosity, hence reduction of vegetable oil viscosity
is an urgent need. The viscosity of vegetable oils can be reduced by using different methods, namely blending, pyrolysis, micro-emulsification and transesterification (Peterson et al., 1991; Ma and Hanna, 1999; Muniyappa et al., 1996). However transesterification methods have been widely used to reduce the viscosity and improved the fuel property of vegetable oil. Transesterifiction is the process of biodiesel production which involves the reaction of fat/oil with alcohol in the presence of acidic, basic or enzymatic catalyst to form esters and glycerol (Agarwal, 2007).
Biodiesel generally is an ester produced from transeseterification by reacting vegetable oil with alcohol. It is biodegradable, non-inflammable, non- toxic and free of sulfur and aromatics. It shows favorable combustion emission profile producing less carbonmonoxide, sulfur oxides and unburned hydrocarbons than petroleum based diesel. These properties make diesel a good alternative fuel to petroleum based diesel oil (Zheng et al., 2006; Song et al., 2000).
The properties of biodiesel can be influenced by several factors such as fatty acid composition of the parent vegetable oil or animals fat, the quality of the feedstock in the production process and other materials used in the process as well as post-production materials. Biodiesel is a mixture of fatty acids with each contributing to the properties of the fuel (Knothe, 2005). The nature of fuel component ultimately determine the fuel properties in a particular biodiesel. The properties of biodiesel fuel that are determined by the structure of its component fatty esters include the following: density, viscosity, lubricity, cold flow properties
cloud and pour point (Knothe, 2005). Other properties that affect biodiesel fuel properties include: flash point, specific gravity, acid number, moisture content (Weiksner et al, 2006).
Vegetable oil also known as triglycerides consist of glycerides, an ester formed from glycerol molecules and fatty acids, involves straight vegetable oil comprised of 98 percent triglycerides and small amount of mono and diglycerol. Triglycerides are ester of three molecules of fatty acid and the glycerol which contain substantial amount of oxygen in their structure. The fatty acids vary in their carbon chain length and the number of double bond. A different type of oil has different fatty acids; The empirical formula and structure of various fatty acids present in vegetable oil are given in Table 1.1 below (Barnwal and Sharma, 2005).
Table 1.1 Fatty Acid Composition of Triglycerides
xx- indicates number of carbon and y indicates number of double bounds in fatty acid chain. Source – Barnwal and Sharma (2005)
Chemical name of Fatty Acid
COCONUT (Cocos nucifera)
Fig 1. Coconut palm (Cocos nucifera).