University of Lucknow

Jatropha as Bio-Diesel

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Courtesy of University of Lucknow


Jatropha curcus L. belongs to the family Euphorbiaceae. It is believed to be a native of South America & Africa but later spread to other continents of the world by the Portuguese settlers. The Arabs have been using this plant for medicinal purpose. Today it is found in almost all the tropical & subtropical regions of the world.

There are more than 200 names for it all over the world, which indicates its significance to man and the various possibilities of its use.

In India, Jatropha curcus is found in almost all the states and is generally grown as a live fence for protection of agricultural field from damage by livestock as it is not eaten by cattle or goat.

It can be easily propagated on massive scale by direct seeding as well as planting stems cuttings. Hot & humid weather is preferred for good germination of seed. Plants bear fruits in the beginning of winter. Approximately 5-6 Kgs of seed is adequate to raise 1 hectare of plantation. The spacing maintained is about 2m ×2m & for high density planting 2m × 1m distance can be recommended. Seeds or cutting can be directly planted in the main field. Sometimes the seedlings are grown in polybags & then transplanted in the main field. Apart from organic manure, mixtures, fertilizers containing NPK should be applied near the planting hole. To keep the land free from weeds in the initial stage, 3-4 hand weeding are necessary; it does not require supplementary irrigation. However, the approximately yield of 1200 Kg seed per hectare may be obtained from irrigated plantation in comparison to 750 kg seed(per hectare) from rain fed plantations. This is expected from third year onwards. The economic life of a plant is about 35-40 yrs. Jatropha oil is extracted by hydraulic press method after grinding & steaming of the seed.

Chemical Analysis of Jatropha:-
The chemical analysis of Jatropha curcus oil:-
Acid value : 38.2
Saponification value: 195.0
Iodine value : 101.7
Viscosity (31 o ­C) cp: 40.4

Fatty Acid Composition: - Palmitic acid%: 4.2
Steric acid %: 6.9
Oliec acid %: 43.1
Linoleic acid %: 34.3
Other acid %: 1.4

The protein content in Jatropha oil cake may be used as a raw material for plastic & synthetic fiber. Vegetable oils can be directly used in diesel engines as they have a high cetane number & calorific value very close to diesel. Vegetable oils offer the advantage of freely mixing with alcohols & these blends can be used in the existing diesel engines without modifications. Blending of vegetable oils with methanol results in significant improvement in their physical properties.

Jatropha as bio-diesel:-
Oil was extracted using n-hexane in a Soxhlet apparatus. Solvent was removed in a rotavapours. The extracted seed meals were thoroughly air dried to remove traces of solvent. The extracted seed meals were immediately analyzed for some physicochemical properties (iodine value, saponification value, acid value, refractive index. Specific gravity, viscosity) by methods described by the Association of Official Analytical Chemists. [AOAC; 1984].

The free fatty acid was calculated from the relationship given by Norris (1965). The mean molecular mass was estimated from the relationship:

56 × 100
Saponification Value

(Ajiwe; 1995)

Proximate analysis of the seed was carried out as described by the Association of Official Analytical Chemists. [AOAC; 1995].Fatty acid composition of the oil was determined as described by Akintayo (1997). Lipids were separated on silica gel plates (20 ×20 cm). The mobile phase was a mixture of petroleum ether: diethyl ether: acetic acid (80:20:1). The plates were developed and bands were identified by reference to known RF values and standards (Sanders, 1983). The sterol fractions obtained by TLC separation from the unsaponifiables of the oils, were derivatised and analyzed (Akintayo & Bayer; 2002). Further determination of the sterol was carried out on a GC- MS Varian MAT 112 S using an ionization voltage of 60 eV.

Jatropha oil was converted into its methyl ester by the transesterification process. These involve making the triglycerides of Jatropha oil to react with methyl alcohol in the presence of the catalyst (NaoH/ KoH) to produce glycerol & fatty acid ester. Specified amount (1000ml) of Jatropha oil (450ml) methanol & (10g) NaoH were taken in a round bottom flask. The contents were stirred till ester formation begins. The mixture was heated to 70oC & held at that temperature without stirring. Two layers were formed –the bottom layer consisted of glycerol & top layers ester.

Jatropha oil resulted in a slightly reduced thermal efficiency as compared to diesel.

It was reported by M. Senthil, that the ignition delay & combustion duration are increased with both Jatropha oil & methyl ester of Jatropha oil as compared to diesel. Lower heat release rates are found with Jatropha oil & methyl ester of Jatropha oil as compared to diesel during the pre-mixed combustion phase.

On the whole, this crop is gaining momentum as “Future Fuel” after the Jajaba. There is some belief that use of Jatropha oil as fuel may bring down the pollution level. It has been successfully used to work any kind of engine. It can be used to run generators as well. It is diluted with 80% petrol-diesel. Its greatest merit is that it is bio-degradable & non- toxic & therefore eco-friendly.

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