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The petroleum product adulteration and its effect in Nigeria.


Origin of Petroleum and its Products:

Petroleum is known to originate from dead fossils (sea animals) deposited over millions of years ago, decayed and buried for years, and under the action of temperature, pressure and micro-organisms is transformed into petroleum or crude oil beneath the sea. Since the birth of automotives in the 19th century, diesel and gasoline are used as the primary source of energy for vehicles, though many alternate fuels like CNG, LPG, alcohol, dimethylether, biodiesel, methanol etc are emerging in the market. The conventional fuels are basically derived from crude oil, where crude oil is fractioned by continuous distillation into several fractions: Petrol (gasoline), kerosene (kerosene, paraffin oil), diesel (gas oil or heavy oil), vacuum gas oil, naphtha, lubricating oil and residue. These fractions are further processed through conversion, reforming and treatment processes to increase the yields, adjust the chemical composition and to remove any trace of impurities.

Several streams are blended to produce petroleum products with the derived specifications. According to George, V and Dyroff, the composition of crude oil varies with the locality of occurrence, but all contains alkanes (straight and branched chain from about (C1-C40), cycloalkares or naphthenes and aromatic hydrocarbons. The low-boiling fraction of almost all petroleum products is composed of alkanes; it is the composition of the higher boiling fraction, which differs according to the source of the petroleum. In addition, to hydrocarbons there are also present, compounds containing oxygen, nitrogen, sulphur, and met allic constituents.

Codes, standards or specifications for the petroleum products have been laid down in different countries. Natural or other legally enforceable specifications represent the minimum quality that must be supplied and it is implicit that engine designers should ensure that their vehicles will run satisfactorily on such quality fuel.

In Nigeria, the Department of Petroleum Resources (DPR) notifies the requisite specifications for the petroleum products gasoline, diesel and kerosene that are coming into the country or been imported.

Adulteration of Petroleum Products:

According to DPR (Directorate of Petroleum Resources in Nigeria) GAZETTE 2009, vol. 7, No 131, adulteration refers to the "act of weakening or contaminating a substance by adding another substance of lower value to it". Hence petroleum products adulteration are usually carried out by adding substances of lower value to the petroleum products of higher value in order to weaken its strength, increase its volume and thus create room for extra profit margin. It is now a common thing in Nigeria. People use the less expensive product to make up the more expensive one, just to increase the volume and make more money. The material/methodology as well as the discussion below reveal how people carry out this act in Nigeria.

Petroleum Products most frequently referred to Forensic Science Laboratories (FSL) for examination are Petrol (gasoline), Kerosene, Diesel, Aviation Fuel, Lubricating oil, furnace oil, waste oil, etc., These samples are forwarded to FSL for their purity, detection of adulteration, unlawful possession, breach of contract, pilferage, etc., The analysis of these Petroleum Products is prima-facie, a complex task as these are complex mixtures of hydrocarbons obtained by fractional distillation of crude oil of variable nature, yet broadly falling in well recognizable boiling/distillation ranges and having other Physico-Chemical parameters, as for instance specifications laid down by Department of Petroleum Resources.

some common forms of petroleum products adulteration and potential adulterants:

According to ASTM D 1298 /IP 160, Blending or mixing of adulterants into the base petroleum products exists in various forms and both the type and quality of adulterants vary from place to place. Moreover, profitability, availability and blendability are the prominent factors governing the choice of adulterants.

Specific types of adulteration may be broadly classified as follows:

* Blending of relatively small amount of distillate fuels like diesel or kerosene into automotive gasoline.

* Blending variable amount (as much as 30%) of the gasoline boiling range hydrocarbons such as industrial solvents into automotive gasoline.

* Blending small amounts of spent waste industrial solvent such as used lubricants, which would be costly to dispose of in an environmentally approved manner into gasoline and diesel.

* Blending kerosene into diesel, of as much as 20-30 percent.

* Blending small amounts of heavier fuel oils into diesel.

There are several petroleum products in Nigeria, which are close substitute of petrol (premium motor spirit/gasoline), diesel (automotive gas oil) and kerosene are available at considerably lower prices. The consequence is that these products are widely used as adulterants.

Causes of Petroleum products Adulteration:

Financial incentives arising from differential prices of petroleum products are generally the primary course of fuel adulteration.

In Nigeria, diesel is priced higher than kerosene which in turn is priced higher than gasoline. At times scarcity of products can reverse the prices thereby pushing people into adulterating gasoline with kerosene or diesel with kerosene as the case may be. Industrial solvents and recycled lubricants are other materials with very low pricing. Adulteration of gasoline, Diesel and kerosene are indulged primarily due to the significant price difference between these products and the adulterant. Various estimates have been made of the extent of financial loss to the federal government and the oil companies as a result of diversion of kerosene, use of offspec low value hydrocarbons mixed with petrol/diesel, evasion of DPR authorities etc.

Effects/Consequences of Petroleum Products Adulteration:

Adulteration of petroleum products which is currently a very flourishing business in Nigeria, can lead to economic losses, increased emissions and deterioration of performance and parts of engines using the adulterated products. Some of the effects of adulteration are outlined below:

* Malfunctioning of the engine, failure of components, safety problems etc. The problem gets further magnified for high performance modern engines.

* Increased tailpipe emissions of hydrocarbons (HC), carbon monoxide (Co), oxides of nitrogen (Nox), particulate matter (PM) and can also cause increased emissions of air toxin substances.

* Adulteration of petroleum products can cause health problems directly in the form of increased tailpipe emissions of harmful and sometimes carcinogenic pollutants while indirectly in the form of diversion of kerosene to the diesel sector for adulteration, this prompting the use of biomass as domestic fuel which in turn leads to health problems of various types due to indoor air pollution. It may be noted that all forms of adulteration are not harmful pollutants significantly, whereas others have little or no effect on air quality.

* Significant loss of revenue--It is better imagined, the extent of financial loss to the Federal Government as well as the oil companies as a result of diversion of kerosene, use of off-spec, low value, hydrocarbons mixed with petrol and diesel etc. it is estimated that the Nation is losing at least N10bn annually as a result of adulteration of petroleum products.


Determination of the Physical properties/Flash Points of the Pure Components:

Samples of petroleum products namely gasoline, kerosene and diesel (130ml by volume each) were collected and characterized for physical properties- density, specific gravity and viscosity using a mud balance and a viscometer and the readings were taken. The flash points of the samples were also determined with the help of Pensky-Martens Closed-Cup Flash Tester and the readings were taken as well. See table 1.0 below.

Determination of Physical Properties/Flash Points of the Adulterated Products:

At the same time, gasoline was adulterated with kerosene in the ratio of 3:1 i.e three parts of kerosene (150ml) to a part of gasoline (50ml). The physical properties of the mixture were measured and recorded with the help of a mud balance and a viscometer. The ratio was varied to 4:1, 5:1, 6:1 respectively and the physical properties were also measured and recorded. The flash points of the adulterated mixtures were also determined. See table 1.1 below.

Also At the same time, diesel was adulterated with kerosene in the ratio of 3:1 i.e three parts of kerosene (150ml) to a part of gasoline (50ml). The physical properties of the mixture were measured and recorded as above. The ratio was varied to 4:1, 5:1, 6:1 respectively and the physical properties were also measured and recorded. The flash points of the adulterated mixtures were also determined. See table 1.2 below.


Detection of adulterants or adulteration in Petroleum Products is quite a rigorous and cumbersome task owing to the basic fact that they are all made up of hydrocarbons with relatively same background characteristics.

In this study, we took time to go through virtually all parameters of laboratory analysis cutting across all known different kinds of Petroleum Products in existence. This is in the bid to be able to ascertain really, and to have a basic idea of the characteristics of these Petroleum Products in order to be able to tackle adulteration of these products professionally. This section presents the results of data generated by the study with a detailed analysis, interpretation and discussion of the data. The results and discussion are presented below on a test by test basis.

Result of the Density, Specific gravity and Viscosity of the Pure Components:

Table 1.0 below shows the result obtained from the pure components of a petroleum product- kerosene, diesel and gasoline. The volume used for the analysis is the same for each sample (130ml). The properties analyzed are density, specific gravity, viscosity and flash point as tabulated below. The table is telling us that pure component of a petroleum product should be within the range of the tabulated figures, otherwise the product is adulterated.

According to literature, it should also be noted that the flash point of some product varies at times depending on the type of product. For kerosene it ranges for 35-40, for gasoline 32-35 and for diesel 95-105. This is in agreement with the experimental data presented here.

Result of Adulterated Gasoline with Kerosene:

Table 1.1 below shows the experimental values of the pure and adulterated petroleum products (gasoline and kerosene) while fig 1.0 is a plot of the table. The plot shows sp. gravity/viscosity/density against the volume of the mixture. The following can be deduced from the plot.

The specific gravity of gasoline is about 0.5 as shown in the plot, addition of kerosene to the gasoline alters this value and causes an increase in the specific gravity until a value of 0.8 is attained, then further addition of kerosene does not alter the specific gravity value anymore, from this point, the plot remains fairly constant.

The density of the pure gasoline was found to be 0.63 lb/gal from the laboratory analysis and it is also shown in the plot below (fig 1.0). Adulteration of gasoline with kerosene increases the density gradually as shown in the plot ie as the volume of kerosene increases in the mixture, the density increases as well though the increment is not sharp but goes on gradually. It can also be deduced from the plot that the more the volume of kerosene in gasoline, the higher the viscosity of the mixture. From the laboratory analysis, pure gasoline has a viscosity of 0.2 (cp) as shown in the plot. Beyond this value, the gasoline becomes adulterated and this as a result of blending of the product with kerosene. The implication of the adulteration is that it gives rise to knocking in automobile engines.

Fig 1.1 below is a plot of flash point versus volume of mixture (gasoline/kerosene).The flash point of gasoline in its pure state is 35[degrees]c as shown in the plot. The plot is a non linear graph trending positively. It shows that the higher the volume of kerosene in the mixture, the higher the flash point.

Result of Adulterated Diesel with Kerosene:

Table 1.2 and Fig 1.2 below shows the experimental data and the plot of sp.gravity/viscosity/density against volume of mixture (diesel/kerosene). The three plots show a negative trend meaning that the lower the variables in y-axis, the higher the variables in x-axis. From the plot we can deduced that:

The viscosity of pure diesel oil is about 1 (cp) from the laboratory analysis and the plot is shown in fig 1.2 below. Any attempt to alter the composition of the diesel by introducing another product-kerosene brings about a decrease in the viscosity of the diesel as indicated in the plot below.

From the laboratory analysis too, the specific gravity of diesel was found to be 0.88 and the region is shown on the plot above. Beyond this point the specific gravity of the diesel is tampered with and the values go down as shown on the plot.

The density of the diesel was found to be 0.67 (lb/gal) from the analysis and the region is shown on the plot below. Addition of another product-kerosene into the product alters the density. As more kerosene is being added to the diesel, the more the density decreases.

Fig 1.3 below shows flash point against the volume of the mixture (diesel/kerosene). The flash point of unadulterated diesel oil was found to be 95[degrees]c as indicated on the graph, any attempt to change the composition of the diesel with 150(ml) of kerosene brings down the flash point to 35[degrees]c, as more kerosene is being added to the diesel, the flash point picks up again and increases gradually as indicated in the plot.





Result of the Density, Specific gravity and Viscocity of the Pure Components:
Table 1.0: The experimental data for the pure components.

Sample     Volume   Density    Specific   Viscosity   Flash point
(pure)     (ml)     (lb/gal)   gravity    (cp)        ([degrees]c)

Kerosene   130      0.64       0.60       0.6         39
Gasoline   130      0.63       0.50       0.2         35
Diesel     130      0.67       0.88       1.0         95

Result of Adultered Gasoline:
Table 1.1: Experimental data of adulterated
gasoline (gasoline/kerosene mixture)

Vol. of gasoline (ml)   Vol. of kerosene (ml)   Vol. of mixture (ml)

150                     0                       150
50                      150                     200
50                      200                     250
50                      250                     300
50                      300                     350

Vol. of gasoline (ml)   Viscosity (cp)   Density (lb/gal)

150                     0.20             0.63
50                      0.29             0.65
50                      0.40             0.67
50                      0.48             0.68
50                      0.55             0.70

Vol. of gasoline (ml)   Flash point ([degrees]c)   Sp. gravity

150                     35.00                      0.50
50                      37.00                      0.80
50                      37.80                      0.80
50                      38.40                      0.81
50                      38.80                      0.81

Result of Adultered Diesel:
Table 1.2: Experimental data of adulterated
diesel (diesel/kerosene mixture).

Vol. of diesel   Vol. of kerosene   Vol. of mixture   Viscosity (cp)
(ml)             (ml)               (ml)

150              0                  150               1
50               150                200               0.90
50               200                250               0.85
50               250                300               0.76
50               300                350               0.67

Vol. of diesel   Density    Flash point ([degrees]c)   Sp. gravity
(ml)             (lb/gal)

150              0.67       95.00                      0.88
50               0.63       35.00                      0.83
50               0.62       35.40                      0.79
50               0.62       36.60                      0.75
50               0.61       36.80                      0.72


In Nigeria today, adulteration of petroleum product has been the order of the day. Pure petroleum products: kerosene, diesel and gasoline were tested pure and the properties : specific gravity, viscosity, density and flash points were recorded as shown on the table above, at same time the adulterated ones were tested as well and the properties also recorded as can be seen on the tables above. It was observes that the properties varies. This variation in the properties has being causing more harm than good in Nigeria. The Knocking in automobile engines, the fire outbreak in different petroleum product sales outlets, homes etc are all as a result of adulteration. The federal Government of Nigeria should look for a way forward to curtail the menace of petroleum products adulteration.


Article history:

Received 23 January 2014

Received in revised form 19 April 2014

Accepted 26 April 2014

Available online 15 May 2014


The support of laboratory staff in the department of Petroleum Engineering, University of Ibadan, Nigeria, and that of Petroleum Engineering department of Afe Babalola University Ado-Ekiti, Nigeria are acknowledged.


[1] George, V., Dyroff, 1993. "Manual on Significance of Petroleum Products", 6th Edition, ASTM Manual, Series 1.

[2] Malve, M.K., R. Krishnamurthy, B.M. Shinde, 2001. "Journal of Scientific & Industrial Research", 60.

[3] Dhole, V.R., G.K. Ghosal, 1995. "Journal of Liquid Chromatography", 18(9): 1767-1798.

[4] Dhole, V.R., M.P. Kurhekar, K.A. Ambade, 1995. "Journal of Forensic Science Society (Science and Justice)", 35(3): 217.

[5] DPR gazette, 2009, "Adulteration on the rise", 7: 131 p 9.

[6] Visalakshi, A., D. KasthuriBai, L.C. Amutha, K. Kalyani, 2003, "Forensic Significance of Evaluation of Research Octane Number (RON) by Capillary Gas Chromatography" Forensic Science Congress, Mumbai January.

[7] ASTM, D, 1298 /IP 160 "Density, Relative density or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer method".

[8] The World Bank Publications, 2007, "Abuses in fuel market" Note Number 327, September.

(1) Udeagbara, S.G., (2) Ojeh, E.J., (3) Anusiobi, O.J.

(1) Department of Petroleum Engineering, Afe Babalola University Ado-Ekiti, Ekiti State, Nigeria.

(2) Department of Petroleum Engineering, University of Ibaban, Ibadan, Nigeria.

(3) HSE Department, Shell Petroleum Development cooperation (SPDC) Nigeria.

Corresponding Author: Udeagbara, S.G., Department of Petroleum Engineering, Afe Babalola University Ado-Ekiti, Ekiti State, Nigeria.
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Author:Udeagbara, S.G.; Ojeh, E.J.; Anusiobi, O.J.
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:6NIGR
Date:Apr 1, 2014
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