Castor oil is the oil that comes from castor beans. The castor bean contains 50% to 55% oil. The oil itself contains a lot of fatty acids similar to those used in cooking oil, some examples of this are oleic acid, linoleic acid, stearic acid and palmitic acid.
When you look at vegetable oils, castor oil is distinguished differently by the high level of ricinoleic acid which is over 85%. There is no other vegetable oil that has such a high proportion of fatty hydroxyacids. Because it has an unsaturated bond, high molecular weight 298, a low melting point of 5ºC and very low solidification point of between -12ºC to -18ºC it is quite suitable for industrial use. The biggest reason why this happens, is that it has the highest and most stable viscosity of any vegetable oil.
This oil has an ash content of about 0.02% the percentage for sulfur is less than 0.04% .The higher the cetane number(CN), the better the fuel will be when used as a diesel. The CN of the majority biodiesel fuels is actually higher than petro diesel, and the cetane number of castor oil biodiesel is in a good range for diesel engines.
Facts drawn by scientists actually show that castor oil has one of the highest CN when it comes to all the vegetable oils, and also when you throw in all of the other biodiesels they actually have numbers that are lower than the amount for castor oil. Petro diesel is around 45, and yet for most other bio fuels, the figure falls in the range 45 to 65.
However when thinking about biodiesel production, cost plays an important role and castor bean oil is one of the lowest priced oils, which makes it quite effective to use. It has proven itself as one of the most beneficial of all oils to use however they are still doing research to determine other variables as well.