i UNIVERSITY OF GHANA COLLEGE OF BASIC AND APPLIED SCIENCES ASSESSMENT OF GASOLINE QUALITY MARKETED IN ACCRA METROPOLIS, GHANA SAEED KUTIA UBEIDALAH DEPARTMENT OF CHEMISTRY JULY 2015 University of Ghana http://ugspace.ug.edu.gh i UNIVERSITY OF GHANA COLLEGE OF BASIC AND APPLIED SCIENCES ASSESSMENT OF GASOLINE QUALITY MARKETED IN ACCRA METROPOLIS, GHANA BY SAEED KUTIA UBEIDALAH (10442183) A THESIS SUBMITTED TO THE SCHOOL OF GRADUATE STUDIES IN PARTIAL FULFILMENT OF THE AWARD OF DEGREE OF MASTER OF PHILOSOPHY IN CHEMISTRY DEPARTMENT OF CHEMISTRY JULY 2015 University of Ghana http://ugspace.ug.edu.gh ii Declaration I, hereby declare that this submission is my own work towards the award of MPhil Chemistry in the Department of Chemistry, University of Ghana and that, to the best of my knowledge, it contains no material previously published by another person nor material which has been accepted for the award of any other degree of the University, except where due acknowledgement has been made in the text. SAEED KUTIA UBEIDALAH (10442183) ………………………………… ……………………… Student’s Signature Date Certified by: DR. AUGUSTINE K. DONKOR …………………………… ……………………… Principal Supervisor’s Signature Date PROF. ROBERT KINGSFORD-ADABOH ………………………………………… ……………………… Co-supervisor’s Signature Date University of Ghana http://ugspace.ug.edu.gh iii Abstract Premium gasoline is often adulterated with cheaper products (adulterants) like domestic kerosene. Kerosene is more difficult to burn than gasoline and this result in the increase of tailpipe emissions and engine complexities. Having similar physical and chemical properties, the gasoline and kerosene cannot be distinguished easily leading to a complication in identification and quantification of the adulterant. Routine monitoring of gasoline at the pump has been pointed out as essential in the prevention of this adulteration and a number of possible methods have been reviewed as there is no standard method for the detection and quantification of kerosene in gasoline. Most of these methods are not utilized in developing countries like Ghana because they require either specialized laboratory, equipment or chemical hence their implementation involves huge financial budgets. A corollary of this is a need for cheaper and tailored method for monitoring kerosene adulteration in gasoline. This study monitored gasoline adulteration with domestic kerosene in Accra Metropolis by exploring the differences in their acidity levels as a “fingerprint”, determined by using an in-house, simple direct titration (SDT) method. Physicochemical properties of gasoline samples and other petroleum distillate fractions were studied after which simulation of gasoline adulteration with domestic kerosene was carried out and the acidity determined by the SDT method to obtain a calibration plot. The calibration standard was then utilized to estimate the amount of domestic kerosene (adulterant) present in 20 gasoline samples from some retail outlets in Accra Metropolis. Domestic kerosene in the range of 5 - 29% was found in 50% of the stations. This study therefore demonstrated that the method is feasible, cheaper, and does not require specialized laboratory or highly trained personnel to execute. University of Ghana http://ugspace.ug.edu.gh iv Key standard quality parameters of the commercial gasolines were also determined and their compliance with local and international specifications was evaluated. However the gasoline available in Accra Metropolis was found not to conform to standard specifications for Europe, Japan and India. 35% did not conform to specification of Ghana Standard Authority (GSA) as well. University of Ghana http://ugspace.ug.edu.gh v Dedication This work is dedicated to my lovely wife, Mrs. Wasila Ubeidalah and my children for their love, care, and moral encouragement. University of Ghana http://ugspace.ug.edu.gh vi Acknowledgement Glory is to Almighty Allah, the Being above the reach of reason on whom I have depended. My thanks go to Dr. Augustine K. Donkor and Prof. Robert Kingsford-Adaboh for supervising this work. My profound and sincere gratitude goes to Dr. Augustine K. Donkor, my principal supervisor, for his personal commitment and suggestions which were amazing and has immensely contributed to the success of this project. I also wish to express my sincere thanks to the management of TOR, Mr. Augustus Tawiah Wiredu, the quality control manager of Tema Oil Refinery (TOR), who supported this study immensely, Mr Albert Yaw Darko, Mr Amon Nii Quaye, Emmanuel Amarnotey, Mr Solomon Yaboah, Mr Amonoo, Francis Asaare-Amegavi and all staff of the quality control department of TOR, the production department of TOR for their support in spite of their busy schedule. I am very grateful to them also for making available facilities which made this project see the light of day. Many thanks to my colleagues at the department; it’s been wonderful being with you especially Gideon Atinga Akolgo and Linda Addae Fodjour. University of Ghana http://ugspace.ug.edu.gh vii Table of Contents Declaration ............................................................................................................................ ii Abstract................................................................................................................................. iii Dedication.............................................................................................................................. v Acknowledgement ................................................................................................................ vi Table of Contents ................................................................................................................ vii List of Figures........................................................................................................................ x List of Tables ........................................................................................................................ xi List of Abbreviations ........................................................................................................... xii CHAPTER ONE .................................................................................................................. 1 1 INTRODUCTION.......................................................................................................... 1 1.1 BACKGROUND .................................................................................................... 1 1.2 PROBLEM STATEMENT ..................................................................................... 4 1.3 JUSTIFICATION ................................................................................................... 5 1.4 AIM ......................................................................................................................... 6 1.5 OBJECTIVES ......................................................................................................... 7 1.6 ORGANIZATION OF THE RESEARCH ............................................................. 7 CHAPTER TWO ................................................................................................................. 9 2 LITERATURE REVIEW ............................................................................................... 9 2.1 PETROLEUM ........................................................................................................ 9 2.1.1 Significance of petroleum................................................................................ 9 2.1.2 Characterization of petroleum ....................................................................... 11 2.2 PETROLEUM PRODUCTS SUPPLY IN GHANA ............................................ 14 2.3 GASOLINE .......................................................................................................... 17 2.3.1 Gasoline production....................................................................................... 20 2.3.2 Quality of gasoline ........................................................................................ 21 2.4 KEROSENE.......................................................................................................... 27 2.5 METHODS TO CHECK GASOLINE ADULTERATION ................................. 29 University of Ghana http://ugspace.ug.edu.gh viii 2.5.1 Spectroscopic methods .................................................................................. 31 2.5.2 Capacitance change method .......................................................................... 33 2.5.3 Refractive index method................................................................................ 34 2.5.4 Extrinsic marker methods .............................................................................. 35 2.5.5 Electrical conductivity method ...................................................................... 36 2.5.6 Ultrasonic technique ...................................................................................... 37 2.5.7 Titration techniques ....................................................................................... 37 2.6 QUALITY ASSESSMENTS OF GASOLINE AT FUEL STATIONS ............... 38 CHAPTER THREE........................................................................................................... 42 3 METHODOLOGY ....................................................................................................... 42 3.1 MATERIALS........................................................................................................ 42 3.1.1 Chemical reagents ......................................................................................... 42 3.2 SAMPLE COLLECTION..................................................................................... 43 3.3 PHYSICAL AND CHEMICAL PROPERTIES ................................................... 46 3.3.1 Monitoring of acidity levels and pattern of petroleum fractional distillates (Category 1)………. .................................................................................................... 46 3.3.2 Pure gasoline and domestic kerosene (Category 2) ....................................... 47 3.3.3 Gasoline adulterated with domestic kerosene ............................................... 48 3.3.4 Gasoline from retail outlets and reference sites (Category 2) ....................... 49 3.3.5 Data analysis .................................................................................................. 50 CHAPTER FOUR ............................................................................................................. 51 4 RESULTS AND DISCUSSION .................................................................................. 51 4.1 ACIDITY LEVELS AND PATTERN IN PETROLEUM FUEL FRACTIONS . 52 4.2 PHYSICOCHEMICAL PROPERTIES OF GASOLINE AND DOMESTIC KEROSENE..................................................................................................................... 55 4.3 SIMULATION OF GASOLINE ADULTERATION WITH DOMESTIC KEROSENE..................................................................................................................... 57 4.4 IN-HOUSE SIMPLE DIRECT TITRATION (SDT) METHOD OF DETERMINING ACIDITY OF GASOLINE ................................................................. 60 4.5 ESTIMATION OF DOMESTIC KEROSENE ADULTERANT IN GASOLINE IN ACCRA METROPOLIS ............................................................................................ 63 University of Ghana http://ugspace.ug.edu.gh ix 4.6 QUALITY EVALUATION OF GASOLINE SAMPLES FROM ACCRA METROPOLIS ................................................................................................................ 66 4.7 MULTIVARIATE STATISTICAL EVALUATION OF GASOLINE ADULTERATION IN GREATER ACCRA, GHANA .................................................. 87 CHAPTER FIVE ............................................................................................................... 90 5 CONCLUSION AND RECOMMENDATIONS ......................................................... 90 5.1 Conclusion ............................................................................................................ 90 5.2 Recommendations ................................................................................................. 91 References ........................................................................................................................... 92 Appendices .......................................................................................................................... 99 University of Ghana http://ugspace.ug.edu.gh x List of Figures Figure 2.1: Distillation profile of gasoline, kerosene and diesel (Odebunm et al., 2013). .. 18 Figure 2.2: Change of capacitance with the concentration of ethanol at 200 Hz signal frequency (Li et al., 2007) ................................................................................................... 34 Figure 3.1: Map of study area, showing sampling locations (fuel stations) ........................ 44 Figure 4.1: Relationship between % of kerosene in gasoline and total acidity ................... 58 Figure 4.2: Variation of distillation curve of gasoline as a function of kerosene percentage ............................................................................................................................................. 59 Figure 4.3: Calibration plot for acidity and adulterant level by SDT method ..................... 62 Figure 4.4: Calibration plot for acidity and adulterant level by ASTM method ................. 62 Figure 4.5: Distillation curves of Shell samples and GSA limits ........................................ 74 Figure 4.6: Distillation curves of GOIL samples and GSA limits ...................................... 76 Figure 4.7: Distillation curves of Total samples and GSA limits........................................ 79 Figure 4.8: Distillation curves of mixed filling stations samples and GSA limits .............. 81 Figure 4.9: Distillation curves of Ship samples and GSA limits ......................................... 83 Figure 4.10: Distillation curves of TOR samples and GSA limits ...................................... 86 University of Ghana http://ugspace.ug.edu.gh xi List of Tables Table 2.1: Physicochemical properties of some crude oils ................................................. 14 Table 2.2: Gasoline additives and their uses ....................................................................... 20 Table 2.3: Octane model along with their pure-component RONs and MONs .................. 24 Table 2.4: Effect of gasoline volatility on vehicle performance ......................................... 25 Table 2.5: Effects of sulfur on fuel sensitive technologies ................................................. 26 Table 3.1: Gasoline samples from filling stations in Accra Metropolis .............................. 45 Table 4.1: Acidity and other parameters of distillate fractions from Forcados crude oil .... 52 Table 4.2: Acidity and other parameters of distillate fractions from Bonny Light crude oil ............................................................................................................................................. 53 Table 4.3: Acidity and other parameters of distillate fractions from Brass River crude oil 54 Table 4.4: Physicochemical parameters of pure gasoline and kerosene ............................. 56 Table 4.5: Chemical composition of kerosene .................................................................... 57 Table 4.6: Physicochemical parameters of gasoline adulterated with kerosene ................. 59 Table 4.7: Estimated levels of domestic kerosene in gasoline samples .............................. 64 Table 4.8: Gasoline standard specifications for Ghana, Europe, Japan and India .............. 66 Table 4.9: Some quality indicators of the groups ................................................................ 67 Table 4.10: Physicochemical parameters of gasoline samples from Shell filling stations .. 72 Table 4.11: Physicochemical parameters of gasoline samples from GOIL filling stations 75 Table 4.12: Physicochemical parameters of gasoline samples from Total filling stations . 78 Table 4.13: Physicochemical parameters of gasoline samples from Mixed Filling Stations ............................................................................................................................................. 80 Table 4.14: Physicochemical parameters of gasoline from ships ........................................ 82 Table 4.15: Physicochemical parameters of gasoline samples at TOR ............................... 85 Table 4.16: Varimax rotated factor loadings matrix and communalities obtained from principal component analysis for gasoline adulteration. ..................................................... 88 University of Ghana http://ugspace.ug.edu.gh xii List of Abbreviations AAMA American Automobile Manufacturers Association AIAM Association of International Automobile Manufactures AKI Antiknock Index ASTM American Society for Testing and Materials ATK Aviation Turbine Kerosene ATR Attenuated Total Reflectance BOST Bulk Oil Storage and Transportation Company CAP Chemocapacitors CDU Crude Distillation Unit CFR Cooperative Fuel Research CO Carbon Monoxide CP Conducting Polymers CSE Centre for Science and Environment DHA Detail Hydrocarbon Analyzer EEMF Excitation Emission Matrix Fluorescence EPA Environmental Protection Agency ETBE Ethyl Tertiary Butyl Ether EU European Union FBP Final Boiling Point FID Flame Ionization Detector GC Gas Chromatography GHAIP Ghanaian Italian Petroleum Company HACs High Acid Crude Oils HC Hydrocarbons IBP Initial Boiling Point KMO Kaiser-Meyer-Olkin LPG Liquefied Petroleum Gas MON Motor Octane Number University of Ghana http://ugspace.ug.edu.gh xiii MOS Metal Oxide Semiconductors MTBE Methyl Tertiary Butyl Ether NMR Nuclear Magnetic Resonance NOx Nitrogen Oxides OPEC Organization of the Petroleum Exporting Countries ON Octane Number PAHs Polycyclic Aromatic Hydrocarbons PCA Principle Component Analysis PM Particulate Matter RFGs Reformulated Gasolines RON Research Octane Number RVP Reid Vapour Pressure SDT Simple Direct Titration SFC Specific Fuel Consumption SPM Suspended Particulate Matter University of Ghana http://ugspace.ug.edu.gh 1 CHAPTER ONE 1 INTRODUCTION 1.1 BACKGROUND Petroleum, a fossil fuel, supplies more energy to the world today than any other source. For thousands of years, the only sources of petroleum had been surface seeps or tar pits until 1858, when James Miller Williams made the first major commercial oil discovery in North America at Oil Springs, Ontario, he struck oil at a depth of only 18 metres. In the following year (1859), Colonel Edwin L. Drake discovered oil in Titusville, Pennsylvania by drilling to 21 metres. In today's industrialized society, petroleum means power and will hold the centre stage of economies for many years to come (Mather, 1947). Gasoline which had previously been considered a useless by-product of the distillation of crude oil has now taken on a new importance as advancements in technology made possible the mass production of the automobile in early years of the twentieth century (Fagan, 1991). Gasoline is a mixture of several hundred organic volatile compounds, mainly hydrocarbons, ranged from four to twelve carbon atoms with boiling points in the range of 30 – 225 °C (Fialkov et al., 2008). The hydrocarbons present in gasoline are classified as paraffins (normal and branched), naphthalenes (cycloparaffins), olefins and aromatics. The physicochemical properties of gasoline largely depends on the nature of the crude oil from which it originates, the refining process be it distillation, alkylation, hydrocracking, catalytic cracking through which the gasoline is obtained, the end use for which it is University of Ghana http://ugspace.ug.edu.gh 2 produced (automotive competitions, engine performance tests), and the environmental legislation like limits on benzene, aromatics, sulfur, lead, etc in place at the location of production and distribution (Barbeira et al., 2007; Flumignan et al., 2008; Takeshita et al., 2008). Gasoline also contains specified maximum levels of impurities and some minimum level of performance-enhancing additives. For example oxygenates like alcohols (mostly ethanol), ethers are added to gasoline to boost the octane rating (Barbeira et al., 2008). As a result of industrialization and changes in lifestyle the urban metropolis growth is associated with increasing number of automobiles and in most growing cities gasoline or petrol driven vehicles comprise over 80% of the total vehicles registered. In Ghana, the transport sector accounts for over 80 percent of total consumption in 2003 (The World Bank, 2006; Yadav et al., 2013). Transport fuels are often adulterated with other cheaper products or by-product or waste hydrocarbon stream for illegal profits. Adulteration may be as simple as adding regular- grade gasoline to the super-grade gasoline storage tank, which lowers the octane number of the super (Al-Ghouti et al., 2008). Premixed gasoline, a cheaper and lower quality gasoline mixed with lubricating oil is used to adulterate premium gasoline (Victor, 2014). Domestic heating and marine diesel fuels are often used to adulterate more expensive automotive diesel fuel (Kalligeros, et al 2001). Gasohol is adulterated by increasing the fraction of ethanol outside the specified range (Jorge and Barbeira, 2002; Pereira et al., 2006). Diesel is adulterated with kerosene, cyclohexane, crude hexane and turpentine oil (Patra and Mishra, 2002; Roy, 1999). Among the common adulterants for petroleum fuels, kerosene seems to be the most popular while industrial solvents, used lubricants and mixtures of hydrocarbons are the other possible alternatives (Taksande and Hariharan, 2006; University of Ghana http://ugspace.ug.edu.gh 3 Wiedemann et al., 2005). For example, in Nigeria and Tanzania adulteration of gasoline and diesel fuel with kerosene is very common (Gawande and Kaware, 2013; Massawe et al., 2013; Osueke and Ofondu, 2011). Kerosene is a popular adulterant for gasoline because of its similarity in chemical composition due to the overlap in their production. These are mixed with almost no deviation in some specifications of the gasoline (Morello- Frosch et al., 2000). Fuel adulteration has many effects especially on any vehicle that uses it. Adulterants alter the chemistry of the base fuel rendering its quality inferior to the required fuel quality for vehicles, moreover, it affects the combustion dynamics inside the combustion chamber of vehicles increasing the emissions of harmful pollutants significantly (Gawande and Kaware, 2013; Yadav et al., 2013). When kerosene is mixed with gasoline, it does not burn completely and accordingly releases more poisonous emissions like nitrous oxides, carbon II oxide (CO) and particulate matter (PM). This results in pollution, causing acute respiratory infections and other ailments (Roy, 1999). There is also a drastic increase in specific fuel consumption (SFC) and knocking tendency, hence reducing engine efficiency (Obodeh and Akhere, 2010; Usha et al., 2003). The diversion of domestic kerosene for adulteration with higher price fuels like gasoline drastically brings down its availability to the poor households, who turn to biomass for the purpose of cooking. The consequence is indoor air pollution and its attendant health effects (Gupta and Sharma, 2002). Therefore, because of the various problems associated with gasoline adulteration with kerosene as enumerated by several studies, this work seeks to monitor gasoline adulteration University of Ghana http://ugspace.ug.edu.gh 4 with kerosene in Accra Metropolis and offer a cheaper method of detecting the adulteration. 1.2 PROBLEM STATEMENT Adulteration of transport fuel is a widespread issue among oil companies around the globe. In the United States of America biodiesel blends are adulterated with soy oil (Mahamuni and Adewuyi, 2009). In Greece, automotive diesel is adulterated with domestic heating and marine diesel (Kalligeros, et al 2001). The recent suspension by the Brazilian government of the state monopoly of fuel production and distribution, whilst it has created competition for stronger retail business given rise to significant changes in the fuel market in Brazil also opened the road to the criminal practice of adulteration of gasohol (Jorge and Barbeira, 2002; Pereira et al., 2006). In Southeast Asia diesel is adulterated with kerosene, cyclohexane, crude hexane and turpentine oil (Patra and Mishra, 2002; Roy, 1999). Gasoline is widely adulterated with kerosene. In Nigeria, adulteration of gasoline and diesel fuel with kerosene has been very rampant (Gawande and Kaware, 2013; Osueke and Ofondu, 2011). In Sri Lanka kerosene adulteration with diesel was found to be in the range of 0 to 35 % while its adulteration in gasoline in the range of 0 to 48 % in Colombo and its suburbs (Kulathunga and Mahanama, 2013). In Ghana gasoline adulteration with premix fuel and domestic kerosene is a common practice (Victor, 2014). Currently the menace is a very flourishing business in developing countries where prices are usually regulated. Air pollution caused by adulterated fuel emissions, especially nitrogen oxides (NOx), carbon monoxide, hydrocarbons (HC), and suspended particulate University of Ghana http://ugspace.ug.edu.gh 5 matter (SPM) has been a noteworthy matter. Running on gasoline mixed with kerosene leads to a substantive increase in air pollution, because of increased tailpipe emissions of harmful pollutants, as well as deterioration of performance and parts of engines. Some of these adulterations are done with almost no aberration in the analytical properties of automotive fuel hence may not show up in routine analytical tests. Laboratory techniques used in detecting adulteration are very expensive, time-consuming, require specialized personnel and only few are available. While a number of alternative techniques are available for detection and quantification of gasoline adulteration with kerosene, they require specialized equipments or chemicals which still make them not affordable for routine monitoring. In the light of this, monitoring gasoline adulteration on the market and exploring a cheaper, more precise, on-site method of detection and quantification of kerosene in gasoline becomes imperative. 1.3 JUSTIFICATION Clean and green world is the requirement of today, and for this one should think and act as an environmentalist (Krishna et al., 2006). Many governmental regulations have been aimed at minimizing the environmental impact of the automobile. Most regulations initially focused on the automobile and have resulted in automotive technology which significantly reduces vehicle emissions compared to pre-control levels. With this type of progress already achieved via automotive technology, it was apparent that if further gains were to be made, it would be necessary to focus on cleaning up fuels that these vehicles University of Ghana http://ugspace.ug.edu.gh 6 use. One of such change was the wide-scale introduction of unleaded gasoline (Renewable Fuels Foundation, 2009). There are complaints by sections of the general public in Ghana about the increasing rate of fuel adulteration, which is causing damage to vehicle engines in the country and the environment (Attenkah, 2006). Despite the threat posed by kerosene adulterated gasoline and the fact that recent engines demand specific quality, the scrutiny and enforcement of gasoline fuel standards in Ghana cannot be verified. To this end, a study of gasoline quality and its adulteration with kerosene on the market is needed. With the growing drive to deter fuel adulteration and the recognition towards lower vehicular emissions, a cheaper, more precise, on-site method of detecting motor gasoline fuel adulteration with domestic kerosene is needed. It will also prevent subsidized domestic kerosene diversion from the intended targets. 1.4 AIM The objective of this work was to monitor gasoline adulteration with domestic kerosene sold in Accra Metropolis by the use of acidity, determined by using a new method, simple direct titration (SDT) method. University of Ghana http://ugspace.ug.edu.gh 7 1.5 OBJECTIVES The specific objectives are: 1) Monitoring acidity levels and pattern in petroleum fractional distillates from the refining of different crude oils. 2) To study acidity and physicochemical parameters of pure gasoline and kerosene. 3) Simulate adulteration of premium gasoline with domestic kerosene. 4) To develop a simplified in-house titration method (SDT method) for the determination of gasoline acidity and calibration standard. 5) Utilize the calibration standard (Linear regression) from 4 above to estimate amount of domestic kerosene (adulterant) present in gasoline from fuel retail outlets in Accra Metropolis. 6) To compare standard physicochemical properties of gasoline from the fuel stations with local and international specifications. 1.6 ORGANIZATION OF THE RESEARCH The research is organized into five chapters. Chapter one gives the background, the problem statement, justification, aim, objectives, and organization of the research. Related literature is reviewed in chapter two. The review covers petroleum, petroleum products supply in Ghana, gasoline, kerosene, methods to check gasoline adulteration and quality University of Ghana http://ugspace.ug.edu.gh 8 assessments of gasoline at fuel stations. Chapter three is methodology and that covers materials, sample collection, Physical and chemical properties (test methods) and data analysis. Chapter four is results and discussion. Chapter five concludes the thesis, and recommendations are offered. University of Ghana http://ugspace.ug.edu.gh 9 CHAPTER TWO 2 LITERATURE REVIEW 2.1 PETROLEUM The term petroleum, which literally means “rock oil”, is commonly called crude oil. Various theories have been advanced over the years as to the origin of petroleum proposing an animal, vegetable, mineral and even meteoric origin. However, petroleum is believed to be formed from the remains of plants and animals that have been held under tremendous pressure in an aerobic environment for millions of years (Speight, 2002). It is not known exactly when humankind first used petroleum. It is known, however, that ancient people worshipped sacred fires that were fuelled by natural gas seeping to the surface through pores and cracks. It is also known that asphalt, a very viscous form of petroleum, was used to waterproof boats and heat homes as early as 6,000 BC. Asphalt was also used as an embalming agent for mummies and in the construction of the Egyptian pyramids around 3,000 BC. Thus petroleum's usefulness was recognized from the very beginnings of civilization. 2.1.1 Significance of petroleum The reason that oil has such importance is that, it provides the fuel that runs the internal combustion engine. Petroleum's utility to humankind took a giant leap in the late 1800's when it replaced coal as the primary fuel for the machines of the industrial revolution (Fagan, 1991). It is projected by the World Oil Outlook (WOO) that developing countries University of Ghana http://ugspace.ug.edu.gh 10 will experience a more dramatic increase in cars with an extra 800 million over the period 2010–2035 (OPEC, 2013). In today's industrialized society, petroleum means power. It provides the mechanical power to run machines and industries and also the political power that comes from being able to shut down the machines and industries of those who depend on you for their oil supply. As long as we depend on oil to fuel the engines of the world, it will continue to play a major role in our lives. Although oil is primarily an energy source, it is also used as a raw material in manufacturing many other products including; plastics, paints, fertilizers, detergents, cosmetics, insecticides, medicines, solvent for paints, insecticides and even food supplement (Fagan, 1991). As a result of the role that petroleum plays, the organization of the Petroleum Exporting Countries (OPEC), a permanent, intergovernmental organization, was created at the Baghdad Conference on September 10–14, 1960, with the principal aim of safeguarding the collective and individual interests of its members and unifying the petroleum policies of its member countries. OPEC was founded at Iraq’s invitation of Iran, Kuwait, Saudi Arabia and Venezuela. The Organization now comprises 12 Members: Algeria, Angola, Ecuador, the Islamic Republic of Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, the United Arab Emirates and Venezuela. The Organization has its headquarters in Vienna, Austria (Desta, 2003). Ghana has little domestic supply of crude oil; most of its crude oil demand is met by imports from Nigeria, supplements from Europe until the offshore discovery of crude oil in commercial quantities in July 2007 (Oswald and Amoah, 2011). University of Ghana http://ugspace.ug.edu.gh 11 2.1.2 Characterization of petroleum Crude oil is a complex combination of hydrocarbons consisting predominantly of paraffinic (straight and branched-chain alkanes), naphthenic (cycloalkanes or cycloparaffins), and aromatic hydrocarbons. Most commonly found naphthenes are five and six membered rings and occasionally a few rings with seven carbon atoms. Among these, methyl derivatives are the most abundant compounds as compared with the parent bicycle compounds. Crude oils contains up to 50% of such naphthenes. Aromatic compounds rarely amount to more than 15% of the crude oils. These are concentrated in heavy fractions such as gas oil, lubricating oils and the residuum. The alkyl derivatives of the benzene namely toluene and xylene are most common aromatic compounds in petroleum. The other derivatives of benzene include fused compounds, the di-aromatics (naphthalene) and tri-aromatics (Phenentherene or anthracene). Naphtheno-aromatic compounds have also been identified in crude oils. These compounds are abundant in shallow and immature crude oils. Many of these compounds can be related to steroid and triterpennoid structures (Yasin et al., 2013). The hydrocarbons in crude oil have carbon numbers that range from four (C4 or butanes), to large molecules containing more than sixty carbons. Sulfur, oxygen and nitrogen compounds, organometallic complexes notably of nickel and vanadium, and dissolved gases, such as hydrogen sulfide, are also found in crude oil. An “average” crude oil contains 84% carbon, 14% hydrogen, 1-3% sulfur, and approximately 1.0% nitrogen, 1.0% oxygen and 0.1% minerals and salts. Analytical studies indicate that similar hydrocarbons, heterocyclics, metals and other constituents, such as hydrogen sulfide, are present in all crude oils but their proportions vary depending on the crude source (API, 2011). Crude oil varies dramatically in colour, odour and flow University of Ghana http://ugspace.ug.edu.gh 12 properties that reflect the diversity of its origin and the complexity increases with boiling range (Odebunm et al., 2002). With crude oil cost accounting for about 80% of the refinery expenditures, processing cheaper crudes can have a very positive impact on refinery margins and is the single most important determinant for the profitability of an oil company (Hartmann, 2003). A reliable compositional characterization of petroleum is therefore important for the optimization of refining processes, products quality or slate and environmental issues. Crude oils can be fractionated into four different components based on solubility and polarity, namely, Saturates, Aromatics, Resins and Asphaltenes (SARA). Saturates are alkanes and cycloparafins, they are unreactive and therefore constitute stable products. Aromatics do not burn as clean as other hydrocarbons and can cause smoke and carbon deposits, as well as increases the luminosity of the combustion flame. Resins are polar molecules with heteroatoms (N, O, and S); whiles asphaltenes are similar to resin with polyaromatic core and higher molecular weight (Pasadakis et al., 2001). Asphaltenes play an important role in organic deposition during petroleum production and processing. Issues on asphaltenes and solid precipitation have always been highlighted as one of the major fouling precursors. A small change in maltenes component or temperature can initiate asphaltene dropouts (Deshannavar et al., 2010). Crude oil types are typically differentiated by their density (measured as API gravity) and their sulfur content. Crude oil with high sulfur content is called sour crude while sweet crude has low sulfur content. Light (high API) or sweet crude oils are normally more expensive and have larger amount of low and medium fractions (high value products) such as LPG, naphtha and kerosene. Therefore, the lower the API of a crude oil, the lower the University of Ghana http://ugspace.ug.edu.gh 13 value it has to a refiner as it will either require more processing or yield a higher percentage of lower-valued by-products such as heavy fuel oil, which usually sells for less than crude oil. There are basically four groups of crude oil based on API and sulfur. They are light-sweet (30-40° API, <0.5 wt% S), light-sour (30-40° API, 0.5-1.5 wt% S), heavy sour (15-30° API, 1.5-3.1 wt% S) and extra-heavy (<15° API and >3 wt% S) (Stratiev et al., 2010; Wiehe, 2008). The commonly used industry standards of API gravity and sulfur, while important, do not adequately define a crude oil. Another important information of crude oil quality is the organic acid content. Their presence at high concentration may generate a number of problems at equipment operation and especially at crude oil atmospheric-vacuum distillation plants via their acid high corrosion activity. The total acid number of a crude oil is an indicator of the organic acids content in the crude oil. Crude oils with total acid number more than 0.5 mg KOH/g are mostly known to present much problems during processing (Yépez, 2005). High acid crude oils (HACs) represent the fastest-growing segment of global oil production. California, Brazil, North Sea, Russia, China, India and West Africa are known to supply HACs. As a result of lower prices of high acid crude oil feeds (total acid number over 0.5 mg KOH/g crude oil) their processing is one opportunity to increase crude oil processing profit and these types are often termed as opportunity crudes (Ooms et al., 2001; Stratiev et al., 2010). University of Ghana http://ugspace.ug.edu.gh 14 Table 2.1: Physicochemical properties of some crude oils PARAMETER Forcados blend Bonny light Bonny midium Gulf crude Lagomar crude Qua Iboe Specific gravity @ 60/60°F 0.8808 0.8576 0.8845 0.8690 0.8960 0.8706 API gravity @ 60/60°F 29.1 33.4 28.4 31.3 26.4 31.0 Kinematic viscosity (cst) @100°F 7.00 7.16 7.01 5.69 4.49 9.86 Sulfur content (w/w %) 0.11 0.06 0.16 0.09 1.36 0.04 Pour point (°F) +25 +85 +5 +35 -5 +35 Total acid content (mg KOH/g) 0.33 - - - - - Water content (v/v %) 0.08 - - 0.05 - - Source- Odebunm et al., 2013. 2.2 PETROLEUM PRODUCTS SUPPLY IN GHANA Petroleum products marketed in Ghana include; premium gasoline, premix gasoline, liquefied petroleum gas (LPG), diesel, kerosene, aviation turbine kerosene (ATK), and residual fuel oil. Other petroleum products are; refinery gas, ethane, propylene, naphtha, distillate fuel oil, lubricants, white oil, grease, wax and bitumen (Energy Commission, 2006). All the petroleum products needed in Ghana were imported and distributed by the local branches of multinational oil companies like Texaco, Shell, British Petroleum, Mobil and Total until the establishment of Ghanaian Italian Petroleum Company (GHAIP) Ltd, which was licensed as a private limited liability company in 1960 as a fully owned Italian company. GHAIP was renamed as Tema Oil Refinery (TOR) in 1991 after the Government University of Ghana http://ugspace.ug.edu.gh 15 of Ghana became the sole shareholder in 1977. TOR is able to meet only around 70 percent of Ghana‘s demand for petroleum products. In September 1996, the state owned TOR acquired sole responsibility for importing crude oil and refined petroleum products into Ghana. According to the International Bank for Reconstruction and Development and The World Bank (2006), the liberalization of the petroleum sector has allowed private sector participation in the procurement of crude oil as well as the private import of refined products through tenders. Since the beginning of 2004, TOR ceased to have a monopoly on the importation of petroleum products, and from July 2004 it has been prohibited from importing petroleum products. In March 2004, private Oil Marketing Companies (OMCs) participated in the first competitive tender for gasoline with financing provided by a syndicate of banks (The World Bank, 2006). TOR’s maximum production capacity was 28,000 barrels of oil per day in 1990. By 2000 the production capacity had been expanded to 45,000 barrels per day to meet increasing demand. Yet annual diesel, gasoline and kerosene demand growth have been about two to three times the annual real GDP growth, whilst that of LPG has quadrupled. The implications are that gasoline and diesel demand have exceeded the country’s refinery capacity, increasing the risk of supply interruptions. If all the petroleum requirements of the nation are to be met from local refining, the total refinery capacity is projected to reach at least 115,000 barrels of oil per stream day by 2020. This can be achieved by expanding the Tema Oil Refinery to the required size by 2020. TOR was designed to process light and low-sulfur crude oils at a time crude oil prices were very low and tenable in neighbouring Nigeria. As a result of the total dependence on imported oil, the country maintains strategic stocks of petroleum products to minimize disruptions in economic activities in the event of external supply University of Ghana http://ugspace.ug.edu.gh 16 problems (Energy Commission, 2006). Moreover, as the population of the country increases with a corresponding increase in the demand for petroleum products in the midst of bad roads, the government established the Bulk Oil Storage and Transportation Company (BOST) as a state owned company incorporated in 1993 as a limited liability company with the government of Ghana as the sole shareholder. BOST has the mandate to develop a network of Storage tanks and Pipeline infrastructure throughout the country and to keep strategic stocks for Ghana. It has depots across the country, most of which are linked to TOR or the Accra Plains depot by pipeline, to facilitate the transportation and distribution of petroleum products throughout the country. Until May 2001, BOST was responsible for the distribution of petroleum products from its strategically located depots which could be found in the Accra Plains, Mamiwater, Akosombo, Kumasi, Buipe and Bolgatanga. BOST was also made to announce revised petroleum prices on behalf of government (BOST, 2011). Access to petroleum products in Ghana is satisfactory but has to be improved as the population grows. There are presently a total of 1,700 petroleum products retail outlets of which 37% are service stations, 20% are filling stations and 43% are reseller outlets. The total number of retail outlets represents an access ratio of 71 retail outlets per one million people. There are also vendors who sell mainly kerosene, in all rural communities thereby increasing the accessibility of petroleum products in most parts of the country. In addition to the service stations and reseller outlets, the Ministry of Energy, under the Rural Kerosene Distribution Improvement Project (RKDIP), has extended the reach of kerosene retail outlets to 1,540 rural communities by installing 5,000 litre capacity surface tanks for the retailing of kerosene (Energy, 2010). At the peak of high oil prices, nearly all University of Ghana http://ugspace.ug.edu.gh 17 developing countries intervened with price-based policies to mitigate the price increase on the world market for at least one fuel. Policy reversals and postponement of price reform were common, governments that had earlier deregulated fuel prices or adopted automatic price adjustment mechanisms froze and subsidized retail prices, while others that had announced fuel price subsidy removal postponed price reform. Colombia in May 2008 postponed the removal of gasoline and diesel subsidies by a year. Both Jordan and Vietnam were to eliminate subsidies by 2007 but postponed (Kojima, 2013). 2.3 GASOLINE Gasoline is a volatile and inflammable mixture derived from petroleum. Gasoline maybe colourless, pale brown or pink as the colour vary depending on the source (Carson et al., 1995; Ismayyir and Dawood, 2012). Gasoline is used as fuel for vehicles propelled by internal combustion engines in automobiles, planes, buses, boats, and also used as diluents, finishing agent, and industrial solvents (Pohanish, 1984). Other terms for gasoline are petrol and less commonly, motor spirit (Singh et al., 2000). Typically, gasoline contains more than 100 compounds including small amount of benzene, toluene, and xylene (Renewable Fuels Foundation, 2009). However, as many as 1,000 compounds have been identified in some blends (Mehlman, 1990). How the gasoline is made (refinery process) greatly determines which chemicals and how much are present in the mixture and the actual composition varies with the source of the crude petroleum. Generally the composition is made up of Paraffins, Olefins, Naphthenes and Aromatics (PONA). Gasoline also contains specified maximum levels of impurities and some University of Ghana http://ugspace.ug.edu.gh 18 minimum level of performance-enhancing additives (Barbeira et al., 2008; Carson et al., 1995). The hydrocarbons constituents in this range are those that have 4 to 12 carbon atoms in their molecular structure. Some aromatics found in gasoline have high boiling points, they are also unstable, and the source of some residues and gums. Hence the levels of aromatics are often regulated (Wolf, 1995). Gasoline varies widely in their physical and chemical properties, they normally boils between 30ºC -225ºC, Figure 2.1. Figure 2.1: Distillation profile of gasoline, kerosene and diesel (Odebunm et al., 2002). University of Ghana http://ugspace.ug.edu.gh 19 A variety of specially formulated additives are added to gasoline to enhance its quality and performance, and to maintain standards during distribution and storage. These compounds include anti-knock agents, anti-oxidants, metal deactivators, lead scavengers, anti-rust agents, anti-icing agents, upper-cylinder lubricants, detergents, and dyes (IARC, 1989). Many of these additives are also available in diluted forms as over-the-counter products for consumer addition (Renewable Fuels Foundation, 2009). In order to increase the gasoline’s oxygen content the oil industry uses alcohols and ethers, both of which boost the octane rating, which was lowered with lower aromatics limits. Ethanol and Methyl Tertiary Butyl Ether (MTBE) are the primary oxygenates, with Tertiary Amyl Methyl Ether (TAME) and Ethyl Tertiary Butyl Ether (ETBE) used in limited quantities. Recently MTBE are not used as oxygenates due to their effect on the environment. The use of these Reformulated Gasolines (RFGs) is also as a result in limits on benzene, sulfur, and aromatics, and to achieve reductions in Volatile Organic Compounds (VOC), nitrogen oxides (NOx) and other toxics emissions (Wolf, 1995). The composition of gasoline has changed significantly as commercial gasoline is produced by mixing different refinery streams at predefined concentration levels in order to meet quality market standards (Anderson, 2010). Automotive gasoline is graded based on the quality and the key distinctive quality parameter is the octane number, and more recently, the sulfur level (Adnan et al., 2013). Gasoline is a major profit generator for the petroleum industry where it represents about 70 % of refining profit (Singh et al., 2000). Table 2.2 lists the common additives and why they are used. University of Ghana http://ugspace.ug.edu.gh 20 Table 2.2: Gasoline additives and their uses Additive Purpose  Detergents  Eliminate or remove fuel system deposits  Anti-icers  Prevent fuel-line freeze up  Fluidizer oil  Used with detergents to control intake valve deposits  Corrosion inhibitors  To minimize fuel system corrosion  Anti-oxidants  To minimize gum formation of stored gasoline  Metal deactivators  To minimize the effect of metal-based components that may occur in gasoline  Antiknock compounds (mostly organometallic compounds), e.g methyl cyclopentadienyl manganese tricarbonyl (MMT)  To improve octane number Source: Renewable Fuels Foundation, 2009 2.3.1 Gasoline production James Miller Williams who made the first major commercial crude oil discovery refined the oil he produced and sold the product as lamp oil. In the following year, Colonel Edwin L. Drake discovered oil in Titusville, Pennsylvania. This discovery signaled the birth of the modern petroleum industry in the United State and numerous refineries were built to turn crude oil into kerosene for lamps and into lubricating oils for the machines of the industrial revolution. Gasoline was then considered a useless by-product until the invention of the gasoline engine in 1885 (Fagan, 1991). Originally, “straight-run” gasoline was produced by simple distillation of crude oil without the use of chemical conversion processes. Shortly after 1900, motor vehicles began to appear in growing numbers, and gasoline began to have a marketable value as a refinery product. Around 1912, distillation of crude oil alone could not satisfy the rapidly growing University of Ghana http://ugspace.ug.edu.gh 21 demand for gasoline. At this time, gasoline-range hydrocarbons were recovered from “wet” natural gas. However, only a limited amount of natural gasoline could be included in finished gasoline because of its high volatility and its relatively low anti-knock quality. Since then, petroleum refineries have developed several processes to contribute to the production of gasoline. In general, gasolines are blended from several petroleum refinery process streams that are derived by the following methods: direct distillation of crude oil, catalytic and thermal cracking, hydro cracking, catalytic reforming, alkylation, and polymerization. After the various gasoline streams have been blended, foul-smelling, corrosive, sulfur compounds are removed by hydrogenation (Lane, 1980). At present, the only commercial source of gasoline is petroleum, but it has been produced from shale oil, Athabasca tar sands, and by hydrogenation or gasification of coal (Sax and Lewis, 1987). 2.3.2 Quality of gasoline 2.3.2.1 Knock and Octane Number (ON) of gasoline Knock is an abnormal combustion phenomenon that occurs in spark-ignition engines. Under normal operation, combustion of the air-fuel mixture within the engine cylinder is initiated by a spark and a flame front starts to propagate outwards. If the pressure and temperature of the unburned air-fuel mixture (ahead of the propagating flame front) reach high enough levels, spontaneous auto-ignition may occur in certain spots. This auto- ignition causes an extremely rapid release of much of the chemical energy stored in the unburned mixture, resulting in large pressure oscillations in the cylinder. In turn, these oscillations produce an audible metallic “pinging” sound and if severe enough, they can University of Ghana http://ugspace.ug.edu.gh 22 cause major damage to engine components. This high sound which resembles knocking, is referred as “knocking”, the ability of a gasoline to resist knocking is rated as the octane number (Adnan et al., 2013; Heywood, 1988). The ASTM defines two different types of ONs, the Research Octane Number (RON) and the Motor Octane Number (MON). Both methods use the same standard test engine but differ in the operating conditions. RON is measured in an engine running at 600 rpm and a fuel/air mixture at a temperature of 60°F, while MON is measured with the engine running at 900 rpm and a fuel/air mixture at a temperature of 300 °F (ASTM D-2699, 1999; ASTM D-2700, 1989). The average of RON and MON is known as the Antiknock Index (AKI) (Renewable Fuels Foundation, 2009). At octane levels below 100, the octane number of a given gasoline is the percentage by volume of isooctane in a blend with n-heptane that knocks with the same intensity at the same compression ratio as the gasoline when compared by one of the standardized engine test methods (Ghosh et al., 2006). RON values are typically 8 to 10 numbers higher than MON values and the difference between the RON and MON of a gasoline is called the “sensitivity”(Wolf, 1995). Octane number is a direct function of the composition. Aromatics and branched iso- paraffins have higher octane numbers than the corresponding paraffins. Petrol RON and MON can have an important influence on engine performance and durability when the engine’s octane requirement is not satisfied (Barnett, 2001). Vehicles are designed and calibrated for a certain octane rating and when a customer uses gasoline with an octane rating lower than required, knocking may result. Engines equipped with knock sensors can handle lower octane ratings by retarding the spark timing, but this will increase fuel consumption, impair driveability and reduce power, and knock may still occur. Using University of Ghana http://ugspace.ug.edu.gh 23 gasoline with an octane rating higher than recommended will not cause problems (AECC et al., 2014). Increasing the minimum octane rating available in the market place has the potential to help vehicles significantly improve fuel economy and, consequently, reduce vehicle CO2 emissions. While the improvement will vary by power train design, load factor and calibration strategy, among other factors, vehicles currently designed for 91 RON gasolines could improve their efficiency by up to three percent if manufacturers could design them for 95 RON instead. Octane rating is becoming an especially important limiting factor in future efficiency improvements because new, more efficient engine designs, such as smaller displacement turbo-charged engines, are approaching their theoretical knock limits when using lower octane rated gasoline. Raising the minimum market octane to 95 RON will enable manufacturers to optimize power train hardware and calibrations for thermal efficiency and CO2 emissions. All of these technologies and actions will be needed to meet the highly challenging fuel economy and CO2 requirements emerging in many countries (Worldwide Fuel Charter, 2013). University of Ghana http://ugspace.ug.edu.gh 24 Table 2.3: Octane model along with their pure-component RONs and MONs RON MON RON MON Paraffins n-butane isobutane n-pentane i-pentane n-hexane C6 monomethyls 2,2-dimethylbutane 2,3-dimethylbutane n-heptane C7 monomethyls C7 dimethyls 2,2,3-trimethylbutane n-octane C8 monomethyls C8 dimethyls C8 trimethyls n-nonane C9 monomethyls C9 dimethyls C9 trimethyls n-decane C10 monomethyls C10 dimethyls C10 trimethyls n-undecane C11 monomethyl C11 dimethyls C11 trimethyls n-dodecane C12 monomethyl C12 dimethyls C12 trimethyls 94 102 62 92 24.8 76 91.8 105.8 0 52 93.76 112.8 15 25 69 105 20 15 50 100 30 10 40 95 -35 5 35 90 -40 5 30 85 89.6 97.6 62.6 90.3 26 73.9 93.4 94.3 0 52 90 101.32 20 32.3 74.5 98.8 20 22.3 60 93 30 10 40 87 -35 5 35 82 -40 5 30 80 Naphthenes cyclopentane cyclohexane m-cyclopentane C7 naphthenes C8 naphthenes C9 naphthenes Aromatics benzene toluene C8 aromatics C9 aromatics C10 aromatics C11 aromatics C12 aromatics Olefins/Cyclic Olefins n-butenes n-pentenes i-pentenes cyclopentene n-hexenes i-hexenes total C6 cyclic olefins total C7d total C8d Oxygenates MTBE TAME EtOH 100 82.5 91.3 82.0 55 35 102.7 118 112 110 109 105 102 98.7 90 103 93.3 90 100 95 90 90 115.2 115 108 84.9 77.2 80 77 50 30 105 103.5 105 101 98 94 90 82.1 77.2 82 69.7 80 83 80 78 77 97.2 98 92.9 Source: Ghosh et al., 2006 2.3.2.2 Volatility of gasoline The ability of gasoline to change into vapour is very important since gasoline is metered in liquid form, but must atomize before it enters the cylinder of an engine. Gasoline that vaporize too readily (highly volatile) will cause decreased fuel flow to the engine, resulting in rough engine operation or stoppage known as vapour lock. Conversely, gasolines with University of Ghana http://ugspace.ug.edu.gh 25 lower volatility may cause hard starting and poor warm-up and acceleration, as well as unequal distribution of fuel to the individual cylinders, which may cause knock, Table 2.4. Table 2.4: Effect of gasoline volatility on vehicle performance Volatility too low Volatility too high  Poor cold start  Poor warm up performance  Poor cold weather driveability  Increased deposits in crankcase, combustion chamber, and spark plugs  Unequal fuel distribution in carburetted vehicles  Potentially increased emissions  Hot driveability problems/vapour lock  High evaporative emissions/ canister overload and purge  Fuel economy may deteriorate Source: Renewable Fuels Foundation, 2009 Vapour pressure and distillation characteristics are critically important for both automotive and aviation gasolines, affecting starting, warm up, and tendency to vapour lock with high operating temperatures or high altitudes. Maximum vapour pressure limits for gasoline are legally mandated in some areas as a measure of air pollution control. The distillation (volatility) characteristics of hydrocarbons have an important effect on their safety and performance, especially in the case of fuels and solvents. The boiling range gives information on the composition, properties, and the behavior of the fuel during storage and use. Volatility is the major determinant of the tendency of a hydrocarbon mixture to produce potentially explosive vapours (ASTM D-323, 1999; ASTM D-86, 2000). University of Ghana http://ugspace.ug.edu.gh 26 2.3.2.3 Sulfur in gasoline High sulfur levels in fuel affects many operating systems in vehicles, Table 2.5. Table 2.5: Effects of sulfur on fuel sensitive technologies Technology Sensitivity to fuel quality Key fuel parameter and threshold On board diagnostics medium Sulfur < 150ppm Lean burn high Sulfur < 30ppm Stratified charge, gasoline direct injection high Sulfur < 30ppm Advance catalyst formulation high Sulfur < 30ppm Source: Renewable Fuels Foundation, 2009 Techniques used to reduce noxious emissions, or to reduce fuel consumption, are becoming very sensitive to contaminants in the exhaust stream and for gasoline vehicles. Sulfur content is the most critical parameter, primarily due to its effect on catalyst performance and durability (Barnett, 2001). Upon combustion, fuel sulfur is oxidized to sulfur oxides, primarily sulfur dioxide (SO2) and some sulfur trioxide (SO3). These are known to inhibit catalyst function of automobile exhaust catalyst; they may also be converted to acids and acid mists, that promote rusting and corrosion of engine parts and exhaust systems, and also increase particulate matter (Row and Doukas, 2008). Nitrogen Oxide (NOX) decomposition potential is completely poisoned by sulfur; NOX is a major pollutant of automobiles (Barnett, 2001). Free sulfur or reactive sulfur in gasoline is determined in copper corrosion test; also sulfur in gasoline may also be in the form of mercaptant (Wolf, 1995). The American Automobile Manufacturers Association (AAMA) and the Association of International Automobile University of Ghana http://ugspace.ug.edu.gh 27 Manufactures (AIAM) as well as the Coordinating Research Council recently conducted independent studies and their results support the conclusion that all in-use vehicles will experience improved emission control with lower sulfur gasoline. The Environmental Protection Agency (EPA) of the United States has therefore recommended the use of ultra low sulfur. The European Union (EU) has introduced environmental specifications aimed at providing sulfur free fuels (Row and Doukas, 2008; Worldwide Fuel Charter, 2013). 2.4 KEROSENE The word kerosene which is derived from the Greek word ‘keros’, meaning ‘wax’ was discovered in 1853 by Abraham Gesner, a British physician. He developed a process to extract the inflammable liquid from asphalt, a waxy petroleum mixture. The term “kerosene” is a generic term referring to a fraction of crude oil that boils approximately in the range 145 to 300°C and consists of hydrocarbons approximately in the C9-C16 range. Kerosenes are the lighter end of a group of petroleum substances known as middle distillates, the heavier end being gas oils. They generally consist of a complex mixture of branched and straight chain paraffins and naphthenes (at least 70% by volume), aromatic hydrocarbons such as alkyl benzenes and alkylnaphthalenes (up to 25%) and olefins (less than 5% by volume) (EPA, 2011; Okonkwo et al., 2012). In the UK, kerosene is also known as paraffin and home heating oil. As a result of the higher proportion of paraffins which are saturated hydrocarbons, kerosenes are generally stable products (Chilcott, 2006). Kerosene lamps are widely used for lighting in rural areas, where electrical distribution is University of Ghana http://ugspace.ug.edu.gh 28 not available or too costly for widespread use. Kerosene is therefore regarded as the petroleum fuel for the poor and rural communities (Energy Commission, 2006). There are several refinery processes that make hydrocarbon streams suitable for blending kerosene-range products. Kerosene may be obtained either from the atmospheric distillation of crude oil (straight-run kerosene) or from cracking of heavier petroleum streams (cracked kerosene). The kerosenes can be further treated by a variety of processes to remove or reduce the levels of undesirable components, e.g. sulfur, nitrogen or olefinic materials. This additional processing also reduces compositional variation and enriches components that improve performance (cycloalkanes and isoalkanes). In practice, the major refining processes used are hydrodesulfurization (treatment with hydrogen to remove sulfur components), washing with caustic soda solution (to remove mercaptants and other sulfur-containing components), and hydrotreating (to remove olefins, sulfur- and nitrogen-containing components). For instance, hydrodesulfurized kerosene is obtained by treating a kerosene-range petroleum stock with hydrogen to convert organic sulfur to hydrogen sulfide, which is then removed. These subsequent treatments may blur the distinction between “straight-run” and “cracked” kerosenes (CONCAWE, 1996, 1995). While kerosenes are similar in composition, the precise composition of a specific kerosene- range refinery stream depends on the crude oil from which the kerosene was derived and on the refinery processes used for its production. Because they are complex petroleum derived hydrocarbons, substances in this category are typically not defined by detailed compositional data but instead by process history, physical properties, and product-use specifications (ASTM D-1655, 2001). University of Ghana http://ugspace.ug.edu.gh 29 In Ghana, two main types of kerosene are available, domestic kerosene and aviation turbine kerosene (ATK) used as fuel for aircrafts (CDU, 2007). The acidity expresses the content of macromolecule organic acid normally because aviation kerosene doesn’t contain water-soluble acid as leaving factory. Macromolecule organic acid mainly contains naphthenic acid; higher levels may corrode metal material seriously. Acidity of aviation kerosene is a critical requirement and must be certified before it is used. The acidity level in aviation fuel is capped at 0.015mg KOH/g. This is because above this threshold the jet engine parts can corrode leading to some vital parts of the jet engine becoming insulators instead of conductors. Acidity level of aviation kerosene therefore is a critical requirement and must be certified before it is used (Xing et al., 2008). It is important to note that kerosene is not a synonym for “jet fuels” which are a distinct class of petroleum distillate product containing a range of chemical additives (Chilcott, 2006). 2.5 METHODS TO CHECK GASOLINE ADULTERATION The American Society for Testing and Materials International (ASTM International) has developed and documented the test methods for most of the widely used materials including petroleum products. Many ASTM tests for gasoline, kerosene, diesel and other petroleum products have been standardized and documented. Some of these tests involve determination of physical and chemical properties while others provide a measure of suitability of the fuel for use in automobiles from the point of engine performance / air pollution generated. Though no ASTM test is specifically designed to measure the adulteration of petrol and diesel with kerosene, some tests namely Density test, Evaporation test, Distillation test, Gas Chromatography, may be used to determine the University of Ghana http://ugspace.ug.edu.gh 30 adulteration of fuel. The most traditional methods to qualitatively and quantitatively estimate fuel composition are gas chromatography (GC) (Pedroso et al, 2008) and high- performance liquid chromatography HPLC (Zinbo, 1984). These techniques involve the separation of mixtures of compounds by differential rates of elution by passing through a chromatographic column, governed by their distribution between a mobile and a stationary phase. Infrared spectroscopy has been reported for quantitative analysis of ethanol and methanol in fuels by using Attenuated Total Reflectance (ATR) (Battiste et al, 1981). Nuclear Magnetic Resonance (NMR) can be coupled with pattern recognition chemometric models as an analytical tool to determine the quality of gasoline. NMR spectroscopy has especially become a powerful tool for gasoline analysis without pre-treatment, mainly due to the fact that measurements are fast and can be automated, allowing the analysis of a large number of samples in a short period of time. In general, the typical chemical shifts in the spectrum are subdivided into regions and each one is associated with a specific molecular substructure, for example, aromatic, olefinic, and aliphatic hydrogen. A huge amount of data in NMR fingerprinting is produced, and chemometric analysis is frequently needed to extract the desired information (Monteiro et al., 2009). In another approach, related to origin determination purposes, Rigo et al. (2009) combined hydrogen nuclear magnetic resonance (1H NMR) fingerprinting of gasoline with pattern-recognition analyses to distinguish Brazilian commercial gasoline, processed in different states of Brazil (Rigo et al., 2009). However, because fuel quality standards and test methods were not designed specifically for detecting adulteration, it means that it is possible to adulterate without violating the standards. The Centre for Science and Environment (CSE) in India after an independent University of Ghana http://ugspace.ug.edu.gh 31 assessment of the fuel adulteration stated that checking for compliance with fuel quality standards does not necessarily imply testing for adulteration. It is important to differentiate between detection of adulteration and monitoring of non-compliance with fuel quality standards. This in other words means that compliance with fuel quality standards does not necessarily mean that fuels are not at all adulterated (Roychowdhury et al., 2002). For more accurate detection, alternative testing methods and protocols have been adopted for surveillance over the world especially in areas where fuel adulteration is practiced. There have been a number of methods proposed for checking adulteration of petrol. 2.5.1 Spectroscopic methods Multidimensional fluorescence techniques like synchronous fluorescence scan (SFS) and excitation emission matrix fluorescence EEMF are used in providing information about samples. For multi-fluorophoric systems, the importance of SFS and EEMF has been well- established (Patra and Mishra, 2002). The resulting excitation–emission data matrix provides a total intensity profile of the sample over the range of excitation and emission. SFS in particular has been found to be useful for the analysis and identification of oils (John, 1976). Polycyclic aromatic hydrocarbons (PAHs) profile varies with the boiling range of the fuel. Low boiling gasoline contains PAHs with a lesser number of fused rings in a molecule, while the PAH fraction in diesel has a higher number of fused rings in a molecule. Hence the PAH profile in kerosene is different from petrol and diesel. Hence, the fluorescence fingerprints corresponding to different fuel compositions. PAHs have good molecular University of Ghana http://ugspace.ug.edu.gh 32 fluorescence properties due to rigid π electron systems in the fused ring structures. This has been shown in a series of works by Patra (2002) and it was possible to introduce some analytical methods based on synchronous fluorescence techniques (Patra and Mishra, 2002a, 2002b). Furthermore, high fluorescence sensitivity allows their determination at very low concentrations. Synchronous fluorescence spectroscopy is a relatively simple and rapid approach for the simultaneous analysis of multi fluorophores. The adulteration of petrol and kerosene can be assessed with a significant accuracy using synchronous fluorescence spectroscopy (Eiroa et al., 2000). Patra and Mishra (2002) discussed recent developments in various synchronous fluorescence methods for analysis of multi-component systems. Single-wavelength fluorescence measurement is limited in its ability to analyze complicated multi-component samples when they have severely overlapping emission and/or excitation spectra. This can be overcome by using synchronous fluorescence scan (SFS), where overlapping of spectra can be minimized. The selectivity of SFS can still be increased by taking derivative spectrum, applying different multivariate methods, selective fluorescence quenching, three- dimensional synchronous measurement or using some of these procedures in combination. The study showed kerosene shifts the SFS maximum of petrol towards the red, whereas, for diesel, a blue shift is observed. Calibration graphs obtained from SFS intensity measurement are found to be efficacious in the whole range ( 0–90% v/v) of kerosene, and gave a good linearity in the adulteration range generally found in the field (0–50% v/v) for petrol and diesel (Patra and Mishra 2002b). University of Ghana http://ugspace.ug.edu.gh 33 2.5.2 Capacitance change method Gas sensors based on capacitive properties or chemocapacitors (CAP) have been used in the study of organic volatile substances. The CAPs have been constructed in different geometries. The most common structure is planar with interdigitated electrodes having as sensitive layer conducting oxides (Ponce et al., 2009). The chemocapacitor is based on the change of capacitance caused by a change of dielectric constant, due the modifications in polarization properties of molecules and/or atoms inside the active layer by external perturbations, such as the interaction with volatile organic compounds (VOC). These layers are permeable for permitting the interaction between the analytes and the sensors (Pearce et al., 2003). This method has been used to study the composition of fuels. Using porous silicon as active layer they studied the dielectric response for methanol-water and ethanol- water. In both systems, increasing the alcohol concentration led to the elevation of the capacitance (Kim et al., 2000). Wiziack et al. (2002) used an array of eight capacitive polymeric sensors to discriminate gasoline, diesel, ethanol and some common fuel adulterants as toluene, hexane and water. These results depend on the polymeric material used as active layer and their interaction with organic volatile compounds (Wiziack et al., 2009). University of Ghana http://ugspace.ug.edu.gh 34 Figure 2.2: Change of capacitance with the concentration of ethanol at 200 Hz signal frequency (Li et al., 2007) 2.5.3 Refractive index method A technique for detection/estimation of adulteration of gasoline/ diesel by kerosene using optical fibre sensor has been reported by Roy (1999). The method of Roy (1999) is particularly suitable for adulteration detection in petrol as its refractive index remains lower than that of core of the optical fibre even after mixing with 50% kerosene which results in smooth ( and almost linear) variation of received power with % adulteration (Gupta and Sharma, 2002). Brazil also suffers from fuel adulteration practice and studies focused on determining fuel composition by refractive index changes in optical fibres have been published. Thus, Falate University of Ghana http://ugspace.ug.edu.gh 35 et al. (2005) studied the vapour of hydrocarbons and possible adulterants in gasoline. In their work they used fibre optics connected to long period gratings to measure changes in attenuation peak wavelength for ethanol gasoline mixtures in different proportions, and adulteration by addition of other solvents such as naphtha, turpentine and paint thinner in Brazilian commercial gasoline (Falate et al., 2005). 2.5.4 Extrinsic marker methods The invention provides a method of detecting an adulterant in gasoline, aviation turbine fuel or diesel, with the help of a marker, wherein the adulterant is kerosene. The method involves detecting the presence of an organo sulphur marker in the fuel. US Patent No. 5229298 (1992) disclosed a method of analyzing nitrogen bearing marker dye concentration in liquid fuels. The concentration of marker has been analyzed by gas chromatography equipped with nitrogen phosphorescence detector using trioctyl amine as internal standard. However, the markers disclosed here are prepared by various expensive protocols and method deals only with the detection of adulteration in gasoline fuels and not in the diesel fuels (Richfield, 1993). Also, US Patent No. 7858373 (2007) discloses various planar six membered cyanurate, isocyanurate or 1, 3, 5- triazine derivative markers to detect the adulteration in various liquid fuels such as commercial gasoline, diesel, biodiesel and ethanol blended gasoline. The presence of marker is determined by mass spectroscopy, as it displays the presence of characteristic m/z peaks of respective markers. However the disclosed markers are synthesized by various steps and hence marker is expensive and requires skilled chemist to understand the symmetry of the molecules and to analyze the data generated by the sophisticated mass spectroscopy (Haas, 2010). University of Ghana http://ugspace.ug.edu.gh 36 2.5.5 Electrical conductivity method There are several types of gas sensors based on the change in electrical dc resistance upon exposure to volatile compounds. They are known as chemoresistive sensors and are usually made from metal oxide semiconductors (MOS), MOS field-effect transistors (MOSFET) or, more recently, from conducting polymers (CP). Such sensors have been widely used to detect reducing and oxidizing gases as, for instance, petrol vapours in filling stations, ethanol in exhaled air etc (Gründler, 2007). CP based sensors have attracted much interest, specially for electronic noses, which are analytical instruments developed to mimic the human nose, and are basically formed by an array of dissimilar gas sensors, that generate different response patterns for different types of smells, attached to a pattern recognition system (Gardner and Bartlett, 1999). The reasons for using CPs for this purpose are that a huge number of different CPs can be synthesized, they respond to a wide range of volatile compounds and they operate at room temperature, which implies in low power consumption and hence, portability (Li et al., 2008). Interestingly, although polyp- xylylenes is known for its excellent insulating property, aryl-substituted derivatives become conducting upon doping and are highly stable to air and humidity, being very convenient for gas sensor. The sensors usually consist of thin (1 – 50 μm) doped polymer films deposited by spin-coating, drop–casting or other technique onto interdigitated electrodes. These, depending on the desired distance between digits can be obtained by several methods as, for instance, circuit printing (Li et al., 2008). University of Ghana http://ugspace.ug.edu.gh 37 2.5.6 Ultrasonic technique The effect of adulteration of petrol by diesel and diesel by kerosene on the speed of sound in the fuel sample has been investigated and has concluded that it is feasible to develop a cheap and easy to operate equipment which measures and uses the measured speed of sound to estimate the adulterants in fuel. Adulteration leads to the change in density as well as viscosity of the fuel. Since both of these parameters influence the speed of sound in a fluid, it is expected that the speed of sound in the adulterated fuel would be different from that in un-adulterated fuel (Gupta and Sharma, 2002). 2.5.7 Titration techniques Phase titration method is one of the old methods used in detecting gasoline adulteration. The method was first investigated by Diamond et al (1988). The method suffered some setbacks and was later modified to a procedure showing considerable improvements. The approach was based on the differences between the solubility of petrol and kerosene in a water-based mixed solvent system arising from the variations in the hydrocarbon content (Diamond et al., 1989). A spectrophotometric titration permits effective end – point detection in turbid metric titrations, and the same approach can also be applied to the clarification titrations depending on removal of turbidity (Kimura et al., 1990). Hence Bahari et al thus used a rapid phase – titration procedure. The study described the objective of providing an alternative experimental procedure for a modified phase – titration method which shows major improvements over currently available approaches and has considerable potential as the basis of an infield method of analysis. The range of kerosene University of Ghana http://ugspace.ug.edu.gh 38 adulteration covered (0 –20% v/v) represents the extremes of adulteration found in the field. They found that the calibration graphs are linear and are therefore especially efficacious for field applications. The method showed no significant dependence on temperature (Bahari et al., 1990). 2.6 QUALITY ASSESSMENTS OF GASOLINE AT FUEL STATIONS In most growing cities, gasoline or petrol driven vehicles comprise over 80% of the total vehicles registered (Kathuria, 2002). It is therefore imperative that the standards for these fuels are regulated by governmental agencies. Unfortunately, in many countries people intentionally add cheaper organic substances in an attempt to raise profit margins (Pereira et al., 2006). Pakistan is one of the countries that have witness a remarkable increase in the number of vehicles within a short period of time creating a corresponding demand for motor gasoline. However, refineries in the region are struggling to produce gasoline that meet the ever growing demand and also comply with the quality specifications of current automobile technology and the environment. Gasoline prices at the pump are mostly higher than other petroleum products making this expensive product attractive for adulteration as it offers higher profit margin. Consequently, gasoline quality issues gained great importance in Pakistan as the general public became conscious of related problems. Yasin et al (2008) took the onus and decided to appraise motor gasoline in the Multan District of Pakistan. Samples were taken from retail outlets of different marketing companies and the University of Ghana http://ugspace.ug.edu.gh 39 physicochemical parameters tested using standard ASTM procedures that are generally used in the assay of gasoline worldwide. The study concluded that the stations gasoline conforms to the specification of Pakistan. However, the gas chromatographic results, showed the presence of heavier carbon chains (C14 and C15), in all the stations sampled. These heavier compounds are not part of gasoline composition and could be present as a result of mixing with heavier products like kerosene (Yasin et al., 2008). Hence despite the measurements of gasoline physicochemical parameters and their complaints with regulations, many adulterated gasolines are approved. Thus in the work of Wiedmann et al (2005), physicochemical parameters like distillation temperatures, Motor Octane Number (MON), Research Octane Number (RON), Antiknock Indices values and ethanol percentage of gasolines obtained from different gas stations in the State of Rio de Janeiro were determined and the results were compared with the Brazilian National Petroleum Agency regulation standards. However the study integrated clusters analysis of the physicochemical parameters in the detection of adulteration in the gasoline. This provided more differences between samples resulting in better discrimination. It also offers an alternative bases for drawing conclusion other than quality specifications (Wiedemann et al., 2005). The Centre for Science and Environment in India did an inspection of motor fuel quality at fuel dispensing stations, oil depots and tank lorries in the suburb of Delhi. In their initial assessment of existing quality monitoring prescribed by the Bureau of Indian Standards, fuel samples were deliberately adulterated and sent to the laboratory for analysis. The University of Ghana http://ugspace.ug.edu.gh 40 findings indicated that the current fuel quality specifications and testing methods for fuel quality monitoring as prescribed by the Bureau are not adequate to catch adulteration. Limited set of tests were therefore adopted for study by the centre, leading to the discovery of stunning irregularities in gasoline samples (Roychowdhury et al., 2002). Kerosene adulteration of commercial fuel (gasoline and diesel) was investigated in the city of Colombo in Sri Lanka. A method based on the polycyclic aromatic hydrocarbons (PAHs) profiles present in different fuel types was developed. Several analytical parameters were evaluated against the level of kerosene added to the synthetic mixtures. The linear regressions with high correlation coefficient were selected as the analytical parameters for the assessment of adulteration of the commercial samples. The results showed that twenty percent of the stations had not adulterated their gasoline and the levels estimated were less than 3 %, another twenty percent had adulteration levels around 15 %. Fifty percent of the stations had adulterations around 30 % and ten percent had an adulteration level as high as 48 %. Quantitative determination of adulteration was easier and more precise (Kulathunga and Mahanama, 2013). In an adulteration identification study of gasoline from service stations in Riyadh, the Resonance Raman spectra and other two spectroscopic techniques were used to study the effects of popular adulterant by adding a known quantity of kerosene to pure gasoline. The fluorescence spectrum for kerosene shows great variation from gasoline and that provide a bases for identification as well as quantification of similar adulteration. The results revealed kerosene adulterations to the magnitude of 60% proportion of the kerosene (Reem, 2008). University of Ghana http://ugspace.ug.edu.gh 41 In the work of Ozaki et al (2009), 40 gasoline samples from fuel service stations in Sao Paulo and had earlier been analyzed by a certified laboratory were subjected to an array of conducting polymers sensors, which provided better discrimination and classification of adulteration (Ozaki et al., 2009). Petrol stations across the city of Pune in India were found to have adulterated their gasoline and diesel fuels with kerosene in the range of 20- 40 percent. The synchronous fluorescence scan technique, as mentioned earlier was employed in quantifying the amount of adulterant (Taksande and Hariharan, 2006). In cognizance of the above, it is clear that there is no guarantee for gasoline quality at the point of sale, hence an urgent need for quality assessment of the product at fuel stations. Obviously, a tailor made method that is cheaper and more precise is necessary for effective appraisal of adulteration. Unfortunately, while the number of vehicles and fuel stations in Ghana has increased tremendously, studies on gasoline quality at the Ghanaian market cannot be verified. The next chapters reports on methods and findings of the assessment of gasoline quality in Accra Metropolis of Ghana. University of Ghana http://ugspace.ug.edu.gh 42 CHAPTER THREE 3 METHODOLOGY 3.1 MATERIALS All the chemical reagents used in this study were of analytical reagent grade and conform to the specifications prescribed by the committee on analytical reagents of the American Chemical Society for the testing of petroleum and petroleum products. The glassware were washed with soap solution, subjected to acid cleaning for about 3 days, rinsed with distilled water and dried in an oven. 3.1.1 Chemical reagents The following chemical reagents were used; potassium hydroxide (KOH), anhydrous isopropyl alcohol, toluene, potassium acid phthalate, phenolphthalein indicator solution, p- naphtholbenzein indicator solution, dye and barium hydroxide. KOH (pellets), barium hydroxide (powder) and potassium acid phthalate (powder) were obtained from AnalaR NORMAPUR, United Kingdom. Toluene and p-naphtholbenzein indicator solution were obtained from BDH, England. Anhydrous isopropyl alcohol was obtained from ALPHA CHEMIKA, Mumbai-India. University of Ghana http://ugspace.ug.edu.gh 43 3.2 SAMPLE COLLECTION Three different categories of samples were collected. The first category was for the examination of physicochemical properties of petroleum distillate fractions (fuels). 1.5 litres each of 15 petroleum fractions were sampled from the crude distillation unit (CDU) of Tema Oil Refinery (TOR). The 15 petroleum fractions consisted of light naphtha, heavy naphtha, kerosene, light gasoil, heavy gasoil, refined from three different types of crude oils; Forcados, Bonny Light and Brass River. The second category was10 litres each of pure gasoline and domestic kerosene collected from TOR for adulteration simulation studies. The third category was motor gasoline purchased from 20 fuel retail outlets in Accra Metropolis (Figure 3.1) and reference (control) samples collected from discharging ships at the Tema Harbour and TOR. Three (3) control samples each were gasoline sampled from different ships at the Tema harbour before discharging and market storage tanks at TOR (Table 3.1). University of Ghana http://ugspace.ug.edu.gh 44 Figure 3.1: Map of study area, showing sampling locations (fuel stations) University of Ghana http://ugspace.ug.edu.gh 45 Table 3.1: Gasoline samples from filling stations in Accra Metropolis and reference sites Name of group Site/Sample # Location Name of company SHELL 1 2 3 4 5 East Legon Kotoka airport 37 Kokomlemle Dansoman SHELL SHELL SHELL SHELL SHELL GOIL 6 7 8 9 Osu Labadi Kwarshieman Sakaman junction GOIL GOIL GOIL GOIL TOTAL 10 11 12 13 14 Haasto Makola Pigfarm Achimota Kanershie TOTAL TOTAL TOTAL TOTAL TOTAL MIXED 15 16 17 18 19 20 East Legon Circle Alajo Lapas Abossey Okai Weija SEL SO NASONA FRAGA OIL ALLIED OIL STAR OIL SHIP 21 Tema Harbour ELAN VITAL 22 Tema Harbour ESHIP EAGLE 23 Tema Harbour NISIDA TOR 24 TOR TOR 25 TOR TOR 26 TOR TOR University of Ghana http://ugspace.ug.edu.gh 46 3.3 PHYSICAL AND CHEMICAL PROPERTIES 3.3.1 Monitoring of acidity levels and pattern of petroleum fractional distillates (Category 1) The petroleum fractional distillates are light naphtha, heavy naphtha, kerosene, light gasoil and heavy gasoil. The acidity contents were determined as indicated below. In addition, the density, distillation temperatures and sulfur contents were measured to characterize the products. Acidity of naphtha and kerosene A weighed amount (95-105g) of sample was dissolved in titration solvent and titrated with alcoholic KOH to a colorimetric endpoint (ASTM D3242). The acidity was expressed as mg KOH/g (Appendix 1). Acidity of gasoil A weighed amount of the gasoil was dissolved in titration solvent and titrated to a potentiometric endpoint using a titroprocessor following ASTM method D664. The acidity was expressed as mg KOH/g (Appendix 2). Density Densities of all fractions were measured following ASTM method D1928. The fraction was brought to a specified temperature and a test portion transferred into a cylindrical container that had been brought to approximately the same temperature. The appropriate hydrometer, also at similar temperature, was lowered into the test portion and allowed to University of Ghana http://ugspace.ug.edu.gh 47 settle. After temperature equilibrium was reached, the hydrometer scale was read and the temperature of the test portion taken. The observed hydrometer reading was reduced to the reference temperature at 15 °C. Distillation temperatures The ASTM method D86 was followed and the manual atmospheric distillation apparatus Herzog HDA 620 was employed. 100mL of sample was placed in a round-bottom flask and heated at a rate specified for a sample with its vapour pressure characteristics. Vapour temperatures were recorded when the first drop of condensate was collected (i.e. initial boiling point) and at recovered volumes of 5mL, 10mL, 15mL, 20mL, and every subsequent 10mL interval. Sulfur Sulfur was determined by ASTM D2622 method and the Horiba sulfur analyzer was used. A test portion of the petroleum fraction was placed in the X-ray beam of the apparatus and the intensity of the sulphur X-ray fluorescence was measured and used to calculate the sulphur content of the sample (ASTM D2622). 3.3.2 Pure gasoline and domestic kerosene (Category 2) Acidity, density, distillation temperatures and sulfur content in pure gasoline and kerosene were measured according to the procedure in 3.3.1; the hydrocarbon composition and RON of the pure gasoline were measured in addition. University of Ghana http://ugspace.ug.edu.gh 48 Hydrocarbon Composition Gas chromatography (GC) method was used and the sample preparation and injection was in accordance with ASTM D5134 employing Agilent 6890N Detail Hydrocarbon Analyzer (DHA), hyphenated with flame ionization detector (FID). The capillary column (DB-1) was of length 40m and diameter 0.099mm, a film thickness of 0.20µm with temperature limits of -60 ºC to 325 ºC. The flow rate inside the column was set at 1.3 ml/min. The temperature programmed 35ºC to 230 ºC was used as follows: Initial temperature of 35 ºC, held for 2.6 minutes, then ramp at 50 ºC/min to second temperature of 45 ºC, held for 3.0 minutes, ramp at 5 ºC/min to third temperature of 60 ºC, held for another 3.0 minutes, then ramp at 9.5 ºC/min to 200 ºC, held for just 1.0 minutes before it ramp to the final temperature of 230 ºC, with a total run time of 27.54 minutes. Each eluting peak was identified by comparing its retention time to a table of retention times, Appendix 3. Research Octane Number (RON) The standard test method for research octane number of spark-ignition engine fuel (ASTM D2699) was adopted. A standardized single cylinder, four-stroke cycle, variable compression ratio Cooperative Fuel Research (CFR) engine was used. 3.3.3 Gasoline adulterated with domestic kerosene Simulated kerosene adulterated gasoline blends were prepared by adding different proportions of the pure domestic kerosene into the pure gasoline. Gasoline and kerosene University of Ghana http://ugspace.ug.edu.gh 49 were mixed in: 100:00, 95:05, 90:10, 80:20, 70:30, 60:40 and 50:50 ratios. Density, distillation temperatures and sulfur content of these synthetic blends were studied. The measurements were in accordance with the procedure described in 3.3.1. The acidity of the adulterated gasoline was measured using the in-house SDT. The standard test method for acidity of kerosene (ASTM D3242) described in 3.3.1 was also employed to measure the acidity of the blends as a verification of the in-house SDT method described below. Acidity of gasoline by simple direct titration (SDT) method A known weight of the sample between 95 to 120g was taken into a 500ml Erlenmeyer flask. Two drops of p-naphtholbenzein indicator solution was added to the sample and the flask swirled to mix. The mixture was then titrated against a standardized 0.01N KOH to a definite colour change and the flask immediately covered. The colour change persisted for at least 10 seconds. The acidity is expressed as milligrams of potassium hydroxide per gram of sample (Appendix 1), required to titrate a sample from its initial colour in p- naphtholbenzein indicator solution to permanent colour change. 3.3.4 Gasoline from retail outlets and reference sites (Category 2) Density, distillation temperatures and sulfur content of the commercial gasolines were measured according to the procedure in 3