Evaluation of Citrillus vulgaris (Watermelon) Seed Oil As a Source of Alternative Energy to Diesel Oil
1Department of Chemistry, Anambra State University, Uli.
2Department of Chemistry, Michael Okpara University of Agriculture, Umudike.
3Faculty of Education, Anambra State University, Uli.
4Department of Chemistry, Nnamdi Azikiwe University, Awka.
*Corresponding Author E-mail: tosmanbaba@yahoo.com
ABSTRACT:
Diesel engines represent most widely used machines in agriculture. The exhaust gases from the combustion of fossil fuels in the engines pollute the environment. Watermelon seed (Citrillus vulgaris) oil was evaluated for its physical and chemical properties as fuel for diesel engines. Oil was extracted from watermelon seed by soxhlet method. The oil yield was 20% and the oil was comparatively analyzed for fuel properties: relative density, refractive index, viscosity, water content, calorific value, gross calorific value ash content and burning characteristics. Trace metal and IR spectra analysis were also determined. Results showed that the watermelon seed oil could be utilized as substitute for diesel oil.
KEYWORDS: Diesel oil, Citrillus vulgaris, alternative, seed oil, fuel properties
Oils are substances derived from plants and animals. Sources of oil include crops such as soya beans, cotton, peanuts, sunflowers, safflowers, flax, rapeseed, mustard and their spices. The fact that they are annuals allows for relatively rapid adjustment of the supply of their oils to meet changing market demands. They are adapted primarily to temperate environments. Oil from oil-bearing trees fall into two categories; edible and inedible. Examples of edible oils include coconut, palm and olive oils. Examples of an inedible oil is Tung oil, which is used for industrial purposes1.
Today, the world relies largely on fossil fuel for the generation of energy to drive automobile and machines. The projected growth rate of world demand for oil estimated at 37% between 2006 and 20302 warrants that researchers and innovators seek alternatives to avert reaching the peak oil too soon. (Peak oil is the point in time when the maximum rate of global petroleum extraction is reached after which the rate of production enters terminal drive.) Literature has shown that oils from African pear seed oil3, rubber seed oil4, palm oil5 and peanut oil6 have been researched for their physical and chemical properties, enabling them to be used as alternative fuel oils in diesel engines.
To avert reaching the peak oil too soon, we have decided to evaluate the physical and chemical properties of Citrillus vulgaris as alternative to diesel oil. In this publication, we present the evaluation of Citrillus vulgaris as alternative to diesel oil.
Watermelon seeds were washed and sun-dried for 3-4 days. They were grounded to powder in a mortar. Oil was extracted from 900g of seed oil by soxhlet extraction using 50ml of petroleum ether. The solvent was distilled off at 80oC. The oil yield was calculated. Diesel oil purchased from Mobil petroleum industry was used as reference standard.
Fuel properties of oil: The extracted oil and diesel oil were comparatively analyzed for their primary fuel properties such as relative density, viscosity, water content, ash content, burning characteristics, calorific value and gross calorific value as outlined by ASTM7 and Institute Petroleum8.
Trace metal analyses were determined by AOCS method9 while the IR analyses were determined using Perkin-Elmer IR spectrometer.
The fuel properties of watermelon seed oil and diesel oil are presented in Table 1.
Parameter |
Watermelon seed oil |
Diesel oil |
|
Relative density at 15oC/ 13oC |
0.9483 |
1.0111 |
|
Viscosity (mm2/s) |
1.45 |
1.51 |
|
Water content (%) |
4.7320 |
5.2132 |
|
Ash content (%) |
0.0232 |
0.0682 |
|
Burning characteristic |
Low sooty flame |
Sooty flame |
|
Calorific value (Kcal) |
795.711 |
750.7302 |
|
Gross calorific value (from density) (kilojoules) |
43.578 |
43.0264 |
The relative density of watermelon seed oil as shown in Table 1 is 0.9483. This value is quite close to that of diesel oil (1.0111). These close values indicate that diesel oil could be substituted with the melon seed oil. The low relative density of the melon seed indicates a good ignition property.
The viscosities of both oils are quite close. The viscosity value of 1.45mm2/s for watermelon seed oil shows that the oil can penetrate across the combustion chamber and would become properly mixed with air. The viscosity value also falls within the standard viscosity range (1.4-1.9 centistokes) for 1 grade fuel.
The water content of both oils is 4.7320% for watermelon seed oil and 5.2132% for diesel oil. These values are very close. The low moisture content indicates lesser tendency to corrosion in engines.
The ash content was in conformity with the ASTM6 (American Standard for Testing and Material) limiting requirement. This means that the seed oil contained low burnable materials which makes it less likely to contribute to injection, fuel-pump, piston and ring wear, since solid ash forming compounds remaining after filtration could cause severe abrasive wear in diesel engine fuel pumps and injection, as well as abrasive wear of pistons rings and cylinder liners.
Burning characteristics: watermelon- low sooty flame, diesel- sooty flame. The burning characteristics results indicate that the seed oil could be substituted for diesel oil.
The calorific values and gross calorific values of both oils are comparatively similar. This indicates that the melon oil would burn completely with a release of high energy that could be utilized to power diesel engine just like diesel oil.
The results of the trace metal analysis have been recorded in Table 2.
Table 2: Trace metal analysis (mg/g)
|
Parameter |
Watermelon seed oil |
Diesel oil |
|
K |
2.000 |
2.000 |
|
Zn |
1.4169 |
0.6767 |
|
Mg |
0.8879 |
0.8859 |
|
Cu |
N.Da |
N.Da |
|
Ca |
6.0108 |
2.4740 |
|
Pb |
N.Da |
N.Da |
|
Mn |
N.Da |
N.Da |
|
Fe |
N.Da |
N.Da |
N.Da = Not detectable
Generally, the trace metal analyses of the two oils are quite similar. The low concentration of the trace metals shows that these metals will not pollute the environment.
The IR spectra of the oils are recorded in Table 3.
Table 3: IR spectra data of diesel and watermelon seed oil
|
|
cm-1 |
|||||
|
|
O-H |
C-H alkenes/ aromatic |
C-H alkanes |
C=O esters |
C=C aromatic |
C-O esters |
|
Diesel |
3166 |
2952 |
2855 |
1746 |
1461 |
1167 |
|
Watermelon seed oil |
3008 |
2952 |
2854 |
1747 |
1457 |
1147 |
The IR spectra of both diesel and watermelon seed oil showed an O-H stretch at 3166 and 3008 cm-1 respectively. C-H stretch for alkenes and aromatic bonds at same 2952 cm-1, C-H stretch for alkanes at 2855 and 2854 cm-1 respectively. Equally both diesel and watermelon seed oil had C=O stretch for esters at 1746 and 1747 cm-1 respectively. At 1461 cm-1 diesel oil had a prominent peak for C=C for aromatic compounds while that of watermelon seed oil occurred at 1457 cm-1, confirming the degree of unsaturation in the oil. C-O deformation for esters occurred at 1167 cm-1 for diesel oil and 1147 cm-1 for watermelon seed oil.
The fuel properties, trace metal and IR spectra analysis of Citrillus vulgaris (watermelon seed oil) have been evaluated and compare with that of diesel oil. Results have shown that Citrillus vulgaris (watermelon seed oil) compare favorably with diesel oil. It is suggested that Citrillus vulgaris (watermelon seed oil) should serve as a source of alternative energy to diesel oil. This is recommendable as researchers and innovators seek alternatives to avert reaching the peak oil too soon.
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Received on 03.10.2010 Modified on 10.11.2010
Accepted on 28.11.2010 © AJRC All right reserved
Asian J. Research Chem. 3(3): July- Sept. 2010; Page 466-467