PRODUCTION AND CHARACTERIZATION OF BIODIESEL FROM LUFFA CYLINDRICA SEED OIL

ABSTRACT

Biodiesel was produced from the seed oil of Luffa cylindrica. The oil obtained was transesterified to produce methyl-esters and glycerol. The percentage oil yield of 36.32% was obtained from Luffa cylindrica seed. Biodiesel properties of methyl-esters were determined using American Society for Testing and Materials (ASTM) Standards and compared with that of petrodiesel. The methyl-ester yield of 92.06 % was obtained from Luffa cylindrica seed oil. Higher viscosity at 40^oC (15.50 mm²/s) was obtained for the seed oil whereas it was reduced to 3.80 mm²/s after transesterification which is comparable with that of biodiesel standards. Lower heating value (29.39 MJ/kg) was obtained for methyl-ester of Luffa cylindrica compared to 42.85 MJ/kg obtained for petro diesel. Higher pour, cloud and flash points of 4 ^oC, 8 ^oC and 150 ^oC respectively were obtained for Luffa cylindrica seed methyl-ester, compared to -12 ^oC, -16 ^oC and 74 ^oC respectively obtained for petrodiesel. Biodiesel produced from Luffa cylindrica seed oil had cetane number (71.93), refractive index (1.465 nm) and relative density (0.88 kg/m²) which is comparable to biodiesel standard. The chemical properties acid value (0.52 mgKOH/g) and iodine value (57.87 mgI₂/g) also compared well with most standard biodiesel. The seed oil of Luffa cylindrica could be a good source of biodiesel.

TABLE OF CONTENTS

Title Page       –           –           –           –           –           –           –           –           i

Certification    –    –           –           –           –           –           –           –           –           ii

Dedication      –              –           –           –           –           –           –           –           iii

Acknowledgements    –           –           –           –           –           –           –           iv

Abstract          – –           –           –           –           –           –           –           –           v

Table of Contents       –           –           –           –           –           –           –           vi

ListofTables  –            –           –           –           –           –           –           –           xi

List of Figures –               –           –           –           –           –           –           –           xii

List of Abbreviations  –  –           –           –           –           –           –           –           xiii

CHAPTER ONE: INTRODUCTION

1.1                   Luffa cylindrica plant –            –           –           –           –           2

1.2                   Biodiesel         –           –           –           –           –           –           3

1.2.1                Advantages and disadvantages of biodiesel  –       –               6

1.2.2                Alcohols used in the production of biodiesel       –           –           7

1.2.3                Methods of biodiesel production            –           –           –           8

1.2.3.1             Single step alkali based transesterification     –           –           8

1.2.3.2             Two step acid-base catalyzed transesterification 9

1.2.3.2.1          Acid-catalyzed esterification      –           –           –           –           9

1.2.3.2.2          Alkaline-catalyzed transesterification –         –           –           10

1.2.4                Catalysts for biodiesel production         –           –           –           11

1.2.5                Influence of free fatty acids on biodiesel production   –          13

1.2.6                Influence of biodiesel composition on fuel properties   13

1.2.6.1             Low temperature operability   –           –                –           –           14

1.2.6.2             Kinematic viscosity     –           –                 –           –           –           16

1.2.6.3             Cetane number            –                 –           –           –           –           17

1.2.6.4             Heat of combustion    –            –           –           –           –           18

1.2.6.5             Lubricity         –           –           –           –           –           –           19

1.2.6.6             Oxidative stability        –           –           –           –           –           20

1.2.6.7             Contaminants and minor components found in biodiesel      –   23

1.2.7                Alternative feedstock for biodiesel production        26

1.2.8                Effects of blending biodiesel with other fuels   –           –           27

1.2.8.1             Biodiesel-petrodiesel blends   –           –           –           –           27

1.2.8.2             biodiesel-alcohol blends          –   –           –           –           –           29

1.2.8.3             Multi-feedstock biodiesel blends        –  –           –           30

1.2.9                Other uses of biodiesel           –      –           –           –           –           31

1.3                   Important by-product of biodiesel production     –           –           32

1.4                   Aim and objectives of the study             –           –           –           32

1.4.1                Aim of the study                 –           –           –           –           –           32

1.4.2                Objectives of the study           –        –           –           –           33

CHAPTER TWO: MATERIALS AND METHODS

2.1                   Materials                  –           –           –           –           –           34

2.1.1                Plant material  –              –           –           –           –           –           34

2.1.2                Instrument/Equipment           –           –           –           –           –           34

2.1.3                Chemicals              –           –           –           –           –           –           35

2.2                   Methods          –           –           –           –           –           –           36

2.2.1                Preparation of seeds    –   –           –           –           –           –           36

2.2.2                Extraction of oil from Luffa cylindrica seeds   –           36

2.2.3                Recovery of oil from solvent  –         –           –           –           36

2.2.4                Physico-chemical properties of the oil extract         36

2.2.4.1             Colour –           –         –           –           –           –           –           36

2.2.4.2             Determination of relative density of the oil extracts-           36

2.2.4.3             Determination of viscosity of the oil extracts —           –           37

2.2.4.4             Determination of iodine value of the oils     –           –           37

2.2.4.5             Determination of peroxide value of the oils   —           –           38

2.2.4.6             Determination of acid value of the oil     –           –           38

2.2.4.7             Determination of saponification value of the oil          38

2.2.4.8             Determination of percentage free fatty acids –           –           39

2.2.5                Biodiesel production by two step acid-base transesterification         –           39

2.2.5.1             Acid pretreatment       –         –           –           –           –           39

2.2.5.2             Alkaline transesterification       –           –           –           40

2.2.6                Determination of Fatty acid profile of biodiesel        40

2.2.7                Physico-chemical properties of the biodiesel  –           –           41

2.2.7.1             Colour –        –           –           –           –           –           –           41

2.2.7.2             Determination of the relative density of the biodiesel    41

2.2.7.3             Determination of the kinematic viscosity of the biodiesel     41

2.2.7.4             Determination of flash point of the biodiesel —           –           42

2.2.7.5             Determination of the heat of combustion of the biodiesel        42

2.2.7.6             Determination of refractive index of the biodiesel  –           43

2.2.7.7             Determination of cloud point of the biodiesel  –           –           43

2.2.7.8             Determination of pour point of the biodiesel – –           –           43

2.2.7.9             Determination of Ash content            of the biodiesel          –           –           –           44

2.2.7.10           Determination of cetane number of the biodiesel   –           44

2.2.7.11           Determination of the acid value of the biodiesel        –             44

2.2.7.12           Determination of the iodine value of the biodiesel    –           45

2.2.7.13           Determination of the peroxide value of the biodiesel                 45

CHAPTER THREE: RESULTS

3.1                   Percentage yield of Luffa cylindrica seed oil extract –           46

3.2                   Physicochemical properties of Luffa cylindrica seed oil          46

3.2.1                Physical properties of Luffa cylindrica seed oil         –             46

3.2.2                Chemical properties of Luffa cylindrica seed oil        –           47

3.2.3                The Gas chromatographic test of Luffa cylindrica seed oil      48

3.3                   Percentage yield of Luffa cylindrica seed oil biodiesel          –  49

3.4                   Fatty acid methyl ester composition of Luffa cylindrica seed biodiesel        49

3.5.0                Physicochemical properties of Luffa cylindrica seed biodiesel          –           50

3.5.1                Physical properties of Luffa cylindrica seed biodiesel           50

3.5.2                Chemical properties of Luffa cylindrica seed biodiesel         52

CHAPTER FOUR: DISCUSSION

4.1                   Discussion               –           –           –           –           –           53

4.2                   Conclusion           –           –           –           –           –           61

4.3                   Suggestions for Further Studies       –           –           –           62

REFERENCES              –           –           –           –           –           –           63

APPENDICES             –           –           –           –           –           –           80

LIST OF FIGURES

Fig.1.1: Luffa cylindrical seed      –           –           –           –           –           3

Fig. 1.2: Luffa cylindrical Fruit        –           –           –           –           –           3

Fig. 1.3: Production of biodiesel        –           –           –           –           –           4

Fig.1.4: Transesterification of triacylglycerols to yield fatty acid alkyl esters (biodiesel)     11

Fig. 3.1: Fatty acids composition of Luffa cylindrica seed oil   –           –   48

Fig. 3.2: Fatty acid methyl ester composition of Luffa cylindrica seed biodiesel      –           49

LIST OF TABLES

Table 3.1: Physical properties of Luffa cylindrica seed oil        –           46

Table 3.2: Chemical properties of Luffa cylindricaseed oil –           –           47

Table 3.3: Physical properties of Luffacylindricaseed biodiesel with the international    biodiesel and petro diesel standards        –           –           51

Table 3.4: Chemical properties of Luffacylindrica seed oil biodiesel with the international   standard biodiesel and petro diesel    –   –           –           52

LIST OF ABBREVIATIONS

AOAC                        American Oil Chemists’ Society

API                 American Petroleum Institute

ASTM             American Society for Testing and Material

AV                  Acid Value

CFPP               Cold Filter Plugging Point

CFR                Code of Federal Regulations

CI                    Compression Ignition

CN                  Cetane Number

CP                   Cloud Point

DAG               Diacylglycerol

EGR                Exhaust Gas Recirculation

EN                   European biodiesel standard

FAAE             Fatty acid alkyl ester(s)

FAEE              Fatty Acid Ethyl Esters

FAME             Fatty acid methyl ester(s)

FFA                 Free Fatty Acids

GC                  Gas Chromatography

IV                    Iodine Value

KOH               Potassium hydroxide

LTFT               Low Temperature Flow Test

MAG               Monoacylglycerol

OSI                 Oil Stability Index

PME                Palm Oil Methyl Ester

PP                    Pour Point

RFS                 Renewable Fuel Standard

RSM                Response Surface Methodology

SCR                Selective Catalytic Reduction

SME                Soybean Methyl Ester

SV                   Saponification Value

TAG                Triacylglycerol

ULSD             Ultra Low Sulphur Diesel

CHAPTER ONE

INTRODUCTION

Biodiesel is an alternative fuel made from renewable biological sources such as vegetable oil and animal fats (Raja et al., 2011). Due to the depleting world’s petroleum reserves, threatening to run out in the foreseeable future and the increasing environmental concerns, there is a great demand for alternative sources of petroleum-based fuel including diesel and gasoline (Sambo, 1981; Munack et al., 2001). Indiscriminate extraction and increased consumption of fossil fuels have led to the reduction of the underground-based carbon resources (Ramadhas et al., 2004). Biofuels are produced from renewable sources; they do not add to the stock of total carbon-dioxide in the atmosphere. These plant forms remove carbon-dioxide from the atmosphere and give up the same amount when burnt within a few years. Hence, biofuels are considered to be “CO₂ neutral” (Ramadhas et al., 2004). The primary goals of National Energy Policy are to increase the energy supplies using mixtures of domestic resources and to reduce our dependency on imported oil or petroleum. As a domestic renewable energy source, biomass offers an alternative to conventional energy sources and supplements national energy security, economic growth and environmental benefits (Ma and Marcus, 1999). Currently, biodiesel is considered a promising  alternative   due  to  its  renewability,  better  gas  emission,  non  toxicity  and  its biodegradability (Hossain et al., 2010). Plant oil and animal fats contain three ester linkages between fatty acids and glycerol which makes them more viscous. Among the techniques applied to overcome the difficulties encountered in using vegetable or animal oil in engines, transesterification of oil to biodiesel seems the most promising (Zhang et al., 2003). The high viscosities of vegetable oils are reduced through the process of transesterification (Alamu et al., 2008). The production of biodiesel from edible and non edible oil has progressively affected food uses, price, production and availability (Rashid et al., 2008). Vegetable oil seeds that do not compete with traditional food crops are needed to meet existing energy demands (Xu and Marcus, 2009). Reducing the cost of the feedstock is necessary for biodiesel’s long-term commercial viability. In order to achieve production cost reduction and make biodiesel more competitive with petroleum diesel, low cost feedstocks, such as non-edible oils, waste vegetable oils could be used as raw material (Xiaohu and Geg, 2009). In this research therefore, attempt is being made to explore the oil of Luffa cylindrica seed from Nigeria in an industrial process for the production of biodiesel.

1. Luffa cylindrica plant.

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