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Background of the Study

The world energy sector depends on the petroleum, coal and natural gas reservoirs to fulfill its energy requirements (Meher et al., 2006). Nigeria is traditionally an energy-deficient country which exports above 70% of its crude oil production. The country is dependent upon import of petroleum products to sustain its growth. Diesel fuel plays an essential function in the industrial economy of Nigeria. The fuel is used in heavy trucks, city transport buses, electric generators, farm equipment etc. (Anjana, 2000). However, diesel engine also emits various forms of pollutants into the environment which can endanger human health and damage the ecological environment (Antolin et a.l, 2002). It is therefore essential that the world extend its interest towards new sources of energy. A relatively new alternative that is currently booming worldwide is fuel obtained from renewable resources or biofuel. Biofuels are well suited for decentralized development i.e can be utilised to meet the needs for social and economic progress, especially in rural communities where fossil fuels may be difficult or expensive to obtain (Nwafor and Nwafor, 2000; Ezeanyananso et al., 2010).

Amongst the various alternative fuels which could match the combustion features of diesel oil and can be easily adapted for use in existing engine technologies with or without any major modifications is biodiesel. Biodiesel fuel produced from vegetable oils (both edible and non edible) or animal fats is one of the promising possible sources that can be substituted for conventional diesel fuel and produces favourable effects on the environment. Biodiesel is recommended for use as a substitute for petroleum diesel mainly because it is a renewable, domestic resource with an environmentally friendly emission profile and is readily available and biodegradable (Zhang et al., 2003).

The research and use of biodiesel fuel as an alternative started in the 1980’s and the reason was the diesel crisis caused by the reduction of petroleum production by the Organization of Petroleum Exporting Countries (OPEC) and the resultant price hike. The biodiesel produced from locally available resources offer a great promise for future application in Nigeria as it can help in attaining much needed energy security and being environment friendly, will help to conform to stricter emission norms (Ezeanyananso, 2010).

Castor plant (Ricinus communis)

Ricinus communis (Plate I) is a species that belongs to the Euphorbiaceae family and it is commonly known as castor oil plant, and Palma christi. Castor oil is possibly the plant oil industry’s most underappreciated asset. It is one of the most versatile of plant oils, being used in over ten diverse industries.

Owing to its unique chemical composition and structure, castor oil can be used as the starting material for producing a wide range of end-products such as biodiesel, lubricants and greases, coatings, personal care and detergent, surfactants, oleochemicals e.t.c. Compared to many other crops, castor crop requires relatively fewer inputs such as water, fertilizers and pesticides. The crop can also be grown on marginal land, thus providing an excellent opportunity for many regions of the world to utilize their land resources more productively (Dokwadanyi, 2011). The plant prefers well-drained moisture relative clay or sandy loan in full sun requires a rich soil and day time temperature above 20oC for seedling to grow well. Castor is native to tropical Africa but it grows widely in Nigeria as weed it can be found in Borno, Sokoto, Jos, Zaria and so many other places in the country (Dokwadanyi, 2011). Though, it has been reported that the plants is not properly exploited, however a fiber for making ropes can be obtained from its stem. The growing plant is said to repel flies and mosquitoes when grown in the garden and it is also said to rid it of moles and nibbling insect, while the leaves have insecticidal properties. (Abdulkareem et al, 2012).

Thevetia plant (Thevetia peruviana)

Thevetia peruviana (Plate II) is an ever – green ornamental dicotyledonous shrub that belongs to Apocynaceae family (Dutta, 1964). It is commonly found in the tropics and subtropics but it is native to Africa, Central and South America. It grows to about 10 – 18 feet high, the leaves are spirally arranged, linear and about 13 – 15 cm in length. There are two varieties of the plant, one with yellow flowers, yellow oleander, and the other with purple flowers, nerium oleander. Both varieties flower and fruit all the year round providing a steady supply of seeds. Grown as hedges, they can produce between 400 – 800 fruits per annum depending on the rainfall pattern and plant age. The flowers are funnel-like with petals that are spirally twisted. The fruits are somewhat globular, with fleshy mesocarp and have a diameter of 4 – 5 cm. The fruits are usually green in colour and become black on ripening. Each fruit contains a nut which is longitudinally and transversely divided. The fruit contains between one to four seeds in its kernel, and the plants bears milky juice in all organs. In Nigeria, Thevetia peruviana has been grown for over fifty years as an ornamental plant in homes, schools and churches by missionaries and explorers (Ibiyemi et al., 2002). All parts of the plant are toxic, due to the presence of glycosides. The toxicity of the glycoside is reflected in the accidental poisonings that occur among children that feed on the seed of the plants (Brewster 1986; Shaw and Pearn 1979). Some adults have reportedly died after consuming oleander leaves in herbal teas (Haynes et al., 1985). According to Saravanapavan Atha (1985), the kernel of about ten fruits may be fatal to an adult while kernel of one fruit may be fatal to children. Generally, small children and livestock are at higher risk of Thevetia peruviana poisoning Livestock poisoning after consuming thevetia has been reported by various workers. For instance Singh and Singh (2002) reported that leaf, stem and bark extracts of the plant killed fish. These extracts together with seed kernel extract also caused poisoning symptoms and death of albino rats (Oji and Okafor, 2000). Pahwa and Chatterjee (1990) reported 80 and 90% mortality of rats that were fed on 20 and 30% kernels of thevetia seed after ten days of feeding.

Statement of Research Problem

The use of vegetable oil for biodiesel production may result in increases in price of food or lead to food shortages (Ezeanya Naso et al., 2010). Fortunately, non-edible vegetable oils, mostly produced by seed-bearing trees and shrubs can provide an alternative, with no competing food uses. Crude non-edible oils however have high free fatty acid (FFA) content, which affects biodiesel yield and capital cost. These oils can be pre-refined by reducing the free fatty acid content (FFA) using esterification and saponification processes. The fuel properties of biodiesel differ from those of petrodiesel fuels. This implies that different engine performance and emissions will occur when biodiesel is used in diesel engines (Carraretto et al., 2004).

Compared to petroleum-based diesel, the high cost of biodiesel is a major barrier to its commercialization; its cost is 150% more than that of petroleum-based diesel depending on feedstock used. Approximately 70-95% of the total biodiesel production cost arises from the cost of feedstock, solvent and refining process of the crude oil (Hass et al., 2006; Umer and Farooq, 2008).

Previous work on biodiesel has not quantified the biodegradability of Castor oil biodiesel. Furthermore, work is still ongoing by scientists on better methods of optimization of Biodiesel.

Justification for Research

Energy is the main driver of socio-economic growth of any nation. It plays a vital role in the overall frame work of development worldwide. Energy is an indispensable commodity and all aspect of human activities is hinged to it, It is also as a factor of production whose cost directly affects price of other goods and services (OPEC, 1994). Access to energy has been described as a key factor in industrial development and in providing vital services that improve the quality of life as well as the engine of economic progress (Singh and Sooch, 2004).

Diesel fuels produced from vegetable oils have practically no sulphur content, no greenhouse gases emissions especially with CO2, offer no storage difficulty, and they have excellent lubrication properties. Moreover, vegetable oils, yielding trees absorb more carbon dioxide from the atmosphere on burning (Erhan and Sharma, 2006). Hence, diesel fuels essentially help to alleviate the increasing carbon dioxide content in the atmosphere. With this development, there has been a renewed focus on vegetable oils to make biodiesel fuels (Kim et al., 2004).

The substitution of diesel oil by renewable fuels produced within the country would generate higher foreign exchange savings, even for the major oil exporting countries like Nigeria. Therefore developing countries can use this kind of project not only to solve their environmental problems but also to improve their economy (Ezeanya Manso et al., 2010). There is need for the production of biodiesel using a cheaper reagent, which contributes to the reduction of capital, and manufacturing cost. Furthermore, more investigations are needed about the fuel properties of biodiesels, diesel fuels and their blends before using in a diesel engine (Hass et al., 2006).

Aims and Objectives

The aim of this research is to produce biodiesel from non-edible oils, optimize methods and compare physico-chemical properties of the biodiesels. Specific objectives are to:

extract the oil from yellow oleander and castor plant using an oil press machine; prepare biodiesels by transesterification; optimize the production process by varying reaction temperature, reaction time, concentration of catalyst and molar ratio of methanol/oil; blend the biodiesels with petro-diesel to improve their fuel properties; determine the flash point, relative density, kinematic viscosity, cloud point, pour point, oxidative stability, calorific value, distillation, sulphur, water content, cetane number, acid value and free fatty acid of diesel, biodiesel and different blends of these in accordance to appropriate ASTM standards and evaluate the biodegradability of the biodiesels and compare with petro-diesel.