Determination of physico chemical properties of biodiesel from Citrullus lanatus seeds oil and diesel blends
Introduction
Energy is an essential driving factor to socioeconomic development in every nation. Its impact touches all aspect of human endeavor such as agriculture, health, education, transportation among others. The major sources of energy supplies in the world are fossil fuels such as petroleum, natural gas, oil and coal. However, fossil fuels are non-renewable and are projected to be exhausted in the near future (Sokoto et al., 2013). Increase in the world population, standard of living, urbanization and industrialization aggravated the depletion of fossil fuel reserves, price increase and more concentration of greenhouse gases emissions and therefore resulted to severe air contamination, environmental and ecological pollutions.
The major problems of using biodiesel in compression ignition (C.I) engines are their high viscosity and low volatility. These affect the atomization and spray patterns of fuel, leading to incomplete combustion and severe carbon deposits, injector chocking and piston ring sticking (Kaisan et al., 2013). Emulsification, Pyrolysis, Dilution and Transesterification were the methods used to reduce viscosity. Transesterification is the most commonly used commercial process to produced clean and environmental friendly fuel.
Conventional fossil fuels used in diesel engine releases higher exhaust emission of particulate matter (PM), carbon dioxides (CO2), sulphur oxides (SOX), unburned hydrocarbon (HC) and oxides of nitrogen (NOX). Moreover, CO2 emission causes the greenhouse effect while NOX and SOX causes’ acid rain (Kaisan et al., 2017a,b,c,d,e). It has been established in the literature that biodiesel considerably decreases the CO and CO2 emission but increases NOX emission. Blending of biodiesel with additives and engine gas recirculation (EGR) were some of the verified methods to have reduced the NOx emissions (Kanji and Pravin, 2013; Mofijur et al., 2013). In addition to that, the fast depletion of petro-diesel due to the rapid growth of world population causes more threat of climatic change and the tragedy of increasing cost (Izah and Ohimian, 2012). Therefore, researchers are seeking for more potential energy crops for biodiesel productions and biodiesel from watermelon seed oil has not been widely investigated (Varala et al., 2012; Oladejo et al., 2013).
Watermelon seed is a family of Cucurbitaceae and believed to have originated from Africa, also cultivated across the world (FOA, 2003). China was reported to be the leading country in the watermelon production followed by Turkey, United States, Iran and Republic of Korea (Huh et al., 2008). In Nigeria, cultivation of watermelon was originally limited to the Northern region, now gradually gaining ground in the southern part of the country (Gwana et al., 2014).
The abundance of watermelon during harvest and absence of its processing industries in Nigeria causes a lot of waste to the non-sweated watermelon and hence, ended up as a waste. The seed were discarded each year as cheap animal feed or simply thrown away and decay naturally (Gwana et al., 2014) and hence, this could be a great alternative source of biodiesel feedstock in Nigeria. However, various technical and economic aspects of watermelon biodiesel required further improvement (Varala et al., 2012; Oladejo et al., 2013). Therefore, this research work is justifiable by all the aforementioned problems.
This article has established how utilization of watermelon seed oil for biodiesel production can be used effectively to generate employment through its mass production/market, and may earn Nigeria the much needed foreign exchange and therefore, reducing poverty, rural-urban migration, environmental pollution as well as climate change associated problems.
Hundreds of scientific articles and various other reports from around the world dealing with biodiesel have appeared in print. However, various vegetable and plant based derived biodiesel that were tested for technical and economic aspects need further improvement. Watermelon seed is a quick maturing plant species that starts bearing fruits within few months of plantation. Although, a study to determine physicochemical properties of oil from watermelon seed and it is suitability for consumption, biodiesel production and other industrial applications were reported (Varala et al., 2012; Oladejo et al., 2013). However, the physico-chemical properties of blended biodiesel produced were hardly evaluated.
Compression ignition engines are classes of internal combustion engines in which the combustion is initialized spontaneously by the virtue of the rise in temperature during the compression process. (Kaisan and Pam, 2013). It works on diesel cycle. In diesel engines, the energy addition occurs at constant pressure but energy rejection is at constant volume. The role of the spark plug in petrol (Spark Ignition) engine is replaced by fuel injector. The compression ratio is from 12 to 25. The engine has low speed, low running cost, high maintenance cost. Compression ignition engines use less volatile liquid fuels (diesel), have compression pressure of 400–700 psi and have no ignition device and the speed/load are controlled varying the fuel quantity injected.
Section snippets
Experimental plan
The discarded watermelon seed could be a great alternative source of raw material of biodiesel production. Though, some biodiesel properties such as flash point, viscosity, cetane number, cloud point, pour point, calorific value, acid value, ash content and cold flow properties had to meet certain standard and be comparable to petro-diesel in order to be regarded as biodiesel (Lee et al., 2008).
Apparatus
Raw materials
The material used in this research was Watermelon seed (Citrullus lanatus), it is widely cultivated
Results and discussion
The fatty acid profile of methyl esters present in Citrullus Lonatus biodiesel are presented in Table 1. The percentage of methyl esters present in the biodiesel was found to be 88.77 as portrayed in the table. Methyl octadecadienoate (C19H34O2) is the most dominating monosaturated methyl ester in the biodiesel profile with 30.80%. It is a very good compound that has the tendency of assigning stability to the biodiesel, because, higher degree of unsaturation in the fatty acid methyl esters
Conclusion
The watermelon biodiesel, its blends and the pure diesel are consistent with the ASTM standards for total sulphur, copper strip and colour index. All the fuel samples are consistent with the ASTM standards with regards to viscosity and specific gravity except B100 which are slightly above the ASTM standard with very negligible values of 0.09 and 0.018 mm2/s respectively. Therefore, the water melon biodiesel and blends could be a better option to be use on CI engines for the improvement of
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