ABSTRACT
Waste frying oils (WFO) sourced from ten different locations using random sampling method were used for biodiesel production in this research. During the esterification process, the time required for mixing the catalyst and methanol mixture was varied between 15 – 30 mins. Hence, 31.5 cm3 of methanol (analytical grade) was added to 150 cm3 of the filtered WFO using 0.75 cm3 of H2SO4 (98%, v/v) as catalyst at 60 oC to reduce the free fatty acid contents of the oils. During the transesterification process, 20 cm3 of methanol was added to 100 cm3 of the WFO using 0.35 g of NaOH as catalyst at a temperature of 60 oC and a reaction time of 40 mins. Biodiesel yield of 17.543 % (lowest yield) and 83.074 % (highest yield) was obtained. The physical and chemical characteristics of the waste frying oil biodiesel were analysed and evaluated. Specific gravity at 20 oC (0.862 + 0.077 to 0.876 + 0.084), kinematic viscosity at 25 oC (18.275 + 1.095 to 82.124 + 5.729), moisture contents (0.246 + 0.060 to 1.333 + 0.049), iodine value (0.381 + 0.062 to 9.644 + 0.763), saponification value (175.311 + 11.130 to 221.605 + 6.240), acid value (0.137 + 0.016 to 1.641 + 0.182), flash point (131.283 + 8.145 to 207.340 + 15.614), cloud point (7.000 + 0.000 to 26.000 + 0.000),pour point (5.000 + 0.000 to 21.000 + 0.000). The conversion of WFO of the ten different WFO samples into valuable fatty acid methyl ester (biodiesel) was successfully conducted. The result obtained showed that the biodiesel from WFOs meets the required specifications if complete pre-treatment process is carried out.
TABLE OF CONTENTS
Title page i
Déclaration
page ii
Certification
page iii
Dedication iv
Acknowledgements v
Table of contents vi
List of Tables xi
List of Figures xii
List of Plates xiii
Abstract xiv
CHAPTER
1 INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the Problem 3
1.3 Aim and Objectives 3
1.4 Justification 4
1.5 Scope and Limitations 4
CHAPTER
2 LITERATURE REVIEW
2.1 Feedstock for Biodiesel Production 6
2.2 Historical Review of Biodiesel Production
from Various Feed stocks 9
2.2.1 Waste frying oils
as feedstock 10
2.2.2 Plant seed oils as feedstock 12
2.2.3 Algae oil as feedstock 15
2.2.4 Other feedstock 16
2.3 Changes in the Physical and Chemical
Properties of Vegetable Oil during Frying 17
2.3.1.Thermolytic reactions 18
2.3.2 Hydrolytic reactions 18
2.4 The Chemistry of Transesterification
Process 20
2.5 Factors Affecting the Production of Biodiesel
from Waste Frying Oil 20
2.5.1
Water content 20
2.5.2 Free fatty acid 21
2.5.3 Type of alcohol 22
2.5.4. The ratio of alcohol to oil 22
2.5.5. Catalyst type 23
2.5.6. Catalyst concentration 24
2.5.7. Stirrer speed 25
2.5.8. Temperature 26
2.5.9. Reaction time 27
2.5.10 pH 27
2.5.11 Purity of reactants 28
2.6 Properties of Biodiesel 28
2.6.1 Viscosity 28
2.6.2 Density 29
2.6.3 Moisture content 31
2.6.4 Flash point 31
2.6.5 Cloud
point and pour point 32
2.6.6 Lubricity
and cold flow 32
2.6.7 Cetane
number 33
2.6.8 Acid number and free fatty acid value 33
2.6.9 Iodine number 34
2.6.10.
Saponification value 35
CHAPTER
3 MATERIALS AND METHODS
3.1 Materials 36
3.1.1 Chemicals and reagents 36
3.1.2 Equipment and apparatus 36
3.2 Methods 38
3.2.1
Study area 38
3.2.2 Sample collection 38
3.2.3 Sample pre-treatment 40
3.2.4 Preparation of stock solution 41
3.2.4 Physico-chemical analyses of samples 46
3.2.4.1
Determination of specific gravity 46
3.2.4.2 Determination of
moisture content 47
3.2.4.3 Determination of
pH 47
3.2.4.4 Determination of
viscosity 48
3.2.4.5 Saponification
value determination 49
3.2.4.6 Determination of
acid value 50
3.2.4.7 Free fatty acid
determination 51
3.2.4.8 Iodine value
determination 52
3.2.4.9 Peroxide value
determination 53
3.2.5 Esterification reaction 54
3.2.5.1 Acid catalysis of
the waste frying oil 54
3.2.5.2
Determination of the free fatty acid value of the esterified oil samples 55
3.2.6 Transesterification reaction 55
3.2.6.1 Calculation of
the molecular weight of the oil 55
3.2.6.2
Calculation of the required volume of methanol and the amount of NaOH 56
3.2.7 Biodiesel production 57
3.2.8 Physico-chemical analyses of the biodiesel 58
3.2.8.1
Determination of flash, cloud and pour points of biodiesel 58
CHAPTER
4 RESULTS AND DISCUSSION
4.1 Results of Physicochemical Parameters of
Waste Frying Oil 61
4.2 Results of the Esterification Reaction 63
4.3 Results of the Transesterification
Reaction 63
4.3.1
Result of the percentage yield of
biodiesel 64
4.4 Results of Physicochemical Parameters of
Biodiesel 64
4.4.1 Specific gravity 64
4.4.2 Kinematic viscosity 66
4.4.3 Moisture content 68
4.4.4 Iodine value 68
4.4.5
Saponification value 69
4.4.6
Acid value 70
4.4.7 Flash point, cloud point and pour point of
the biodiesel 73
4.4.8
Biodiesel storage 75
CHAPTER
5 CONCLUSION AND RECOMMENDATIONS
5.1 Conclusion 77
5.2 Recommendations 78
References 80
Appendices 94
LIST OF TABLES
3.2.2 Description of the Ten Waste Frying Oils 39
4.1 Mean Physico-chemical Parameters of Waste
Frying Oil 62
4.4 Mean Physico-chemical Parameters of Biodiesel
Produced from the WFO 65
LIST OF FIGURES
3.2.1 Aba North Map 38
3.2.4.4 Oswald Viscometer 48
3.2.6.1 General Structure of a Triglyceride 55
LIST OF PLATES
3.2.2 The Waste Frying Oil Samples 40
3.2.9 The Flash Point Tester 59
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND TO THE STUDY
During
the past decades, worldwide petroleum consumption has permanently increased due
to the growth of human population and industrialization which has led to a
drastic reduction in the fossil fuel reserves and fluctuation of the petroleum
price. On the other hand, combustion of fossil fuel contributes to the emission
of greenhouse gases and air contaminants such as CO2, NOx, SOx, CO,
particulate matter and volatile organic compounds which lead to the pollution
of the atmosphere and global warming (Balat and Balat, 2010).
The
fluctuation of petroleum prices and the associated environmental problems have
triggered the need for alternative fuels obtained especially from renewable
sources (Kannahi et al., 2013). Renewable
energy can be considered an alternative to fossil energy. Globally, 15% of
primary energy supply comes from renewable sources (Lund, 2007). Biomass is the
main source of renewable energy resource (McKendry, 2002). Renewable resources
account for about ten percent of the world’s energy consumption and biofuels
and other forms of energy are obtained from the conversion of these renewable
resources (Filho, 2004). Among biofuels, biodiesel is one of the possible
alternatives in the transport sector (Costa Neto, 2000). Many potential raw materials
for biodiesel production abound but currently, edible oils are used for world
biodiesel production (Ahmia et al.,
2014). However, their use for biodiesel production is of great concern because
it competes with their use as food materials (Arjun, et al., 2008).
Waste
frying oil refers to the vegetable oil that has been used for frying food.
Repeated frying for the preparation of food renders the edible vegetable oil unsuitable
for human consumption as a result of the increase in the free fatty acid
content. Waste frying oil is accepted as a suitable material for the production
of biodiesel because it is readily available and cost effective. Biodiesel obtained
from transesterification of vegetable oil with alcohol is one of the forms of
energy which has been given adequate attention by many researchers because of
the advantages associated with its use in the transport sector (Hossain et al., 2010). Biodiesel is a biodegradable,
non toxic and renewable fuel that can be produced from a renewable raw material
including waste and fresh vegetable oils, oils seed plants and animal fats. The
combustion of biodiesel has lower emissions than petroleum based diesel,
whether blended with petroleum diesel or used in its pure form. Biodiesel does
not increase the level of carbon dioxide in the atmosphere and the use of
biodiesel leads to minimization of the intensity of greenhouse effect (Vincente
et al., 2004; Antolin et al., 2002). Also, biodiesel is better
than diesel fuel in terms of biodegradability, sulphur content, aromatic
content and flash point (Martini and Schell, 1997).
The
main purpose of this research is to investigate the production of biodiesel
from ten different waste vegetable oils. Special attention is paid to the
optimization of the production of biodiesel from the ten different waste frying
oils by two step reaction mechanisms which are esterification and
transesterification reactions.
1.2 STATEMENT OF THE PROBLEM
Petroleum is a non-renewable energy source
which implies that the resources of this kind are finite and would run out with
time. The depletion of petroleum reserves, fluctuation of petroleum prices and
the serious environmental damage arising from the use of fossil fuels have led
to the discovery of alternative and renewable energy sources. The combustion of
fossil fuels like petroleum causes various environmental problems including
global warming, air pollution, acid precipitation, ozone layer depletion,
forest destruction (Dincer, 2000). It is important that low cost and
eco-friendly alternatives to petroleum are used and one of such alternatives is
waste frying oil which is not only a much cheaper raw material but can be used
to produce diesel which generates far less green house gases than petroleum
based diesel. However, biodiesel production with WFO is hampered by the increase
in the free fatty acid (FFA) content of such oils and it is important that
optimum condition for this process is determined so as to make the process
reproducible.
1.3 AIM AND OBJECTIVES
The
aim of this research is to investigate the production of biodiesel from ten
different waste frying oils obtained from nine different sources using a 2-step
reaction mechanism which are esterification and transesterification and this
will be achieved through the following objectives:
1
Esterification reaction of the waste
vegetable oil by acid catalyzed reaction with varying mixing time of the
methanol and the acid catalyst.
2
Transesterification of the esterified oil
using methanol and base catalyzed reaction.
3
Determination of the optimum conditions
for transesterification reaction of WFO such as alcohol: oil ratio, mixing
intensity, catalyst type and concentration, reaction temperature and purity of
reactants.
4
Determination of the physico-chemical
parameters of the different oils and their biodiesel derivatives.
1.4
JUSTIFICATION
Energy
is one of the most fundamental requirements for human activities and existence (Izah
and Ohimain, 2013). Unfortunately, there is depletion in the non- renewable energy sources that
contribute over eighty six percent of the global energy supply (Atadashi et al., 2011) since the consumption of
energy increases with the increasing world population. Though, Nigeria is a country
that produces and exports crude oil, it still depends on foreign nations for
the supply of petroleum products like petrol and kerosene. So it becomes
pertinent that Nigeria explores other potential and more eco-friendly means of
energy supply. This research is important because it will determine the
feasibility of small scale production of biodiesel from WFO. Secondly, it will
address the problem of environmental pollution caused by improper disposal of
waste frying oil on land and water.
1.5 SCOPE AND LIMITATIONS
This
research covered the method of producing biodiesel from waste frying oil,
ranging from the esterification reaction to the transesterification reaction of
the esterified oil. It also entailed the detailed analytical methods and
procedures of physico-chemical parameter determination of the oil and biodiesel.
The
limitations involved in this research include the insufficient quantity of raw
materials from different sources for some analyses, unsteady power supply, unavailability
of appropriate equipments such as biodiesel kit which has in-built provision
for a thermometer to ensure that the temperature was maintained at 60 oC.
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