Chemically biodiesel is the methyl esters of long chain carboxylic acids. Method to obtain biodiesel are:
1. Filter cheap or waste vegetable oil/fat/
2. Heat it at 110 C with stirring to remove any water from it.
3. Prepare sodium methoxide from sodium metal and methanol. Add the sodium methoxide about 2% by weight to the vegetable oil or fat.
4. Add methanol about 20% by volume to the, mixture.
5. Heat the mixture with stirring for 30 minutes.
6. Cool and mix sufficient water, stir well. The glycerol and soap dissolve in water phase.
7. Separate the water insoluble phase from water phase
8. Add antioxidants to biodiesel to avoid it to become gummy due to oxidation and polymorphism.
1. Biodiesel is cheaper
2. It has high cetane numbers 46 to 54 and high c.v. of about 40 kJ/m.
3. It is regenerative and environment friendly.
4. It does not give out particulate and co-pollutants.
5. It has certain extent of lubricity.
6. It use provides good market to vegetable oils and reduces over dependence for diesel on foreign countries, saving currency.
7. It is clean to use biodiesel in diesel engines.