Page 129 - Biofuels Refining and Performance

112 Chapter Four

Figure 4.3 Ricinus communis L. (Photo courtesy of Eric Winder
[www.bio.mtu.edu/~jclewin/bahama_pics/Eric/].)

Main uses. Castor bean is cultivated for its seeds, which yield a fast-
drying oil used mainly in industry and medicine. Coating fabrics, high-
grade lubricants, printing inks, and production of a polyamide nylon-type
fiber are among its uses. Dehydrated oil is an excellent drying agent and
is used in paints and varnishes. Hydrogenated oil is utilized in the man-
ufacture of waxes, polishes, carbon paper, candles, and crayons. The
pomace or residue after crushing is used as a nitrogen-rich fertilizer.
Although it is highly toxic due to the ricin, a method of detoxicating the
meal has been developed, so that it can safely be fed to livestock [54].
Several authors have found that castor-oil biodiesel can be considered as
a promising alternative to diesel fuel. Transesterification reactions have
been carried out mainly by using both ethanol and NaOH, and through
enzymatic methanolysis [55–57]. Several authors have studied the influ-
ence of the nature of the catalyst on the yields of biodiesel from castor oil.
They found that the most efficient transesterification of castor oil
could be achieved in the presence of methoxide and acid catalysts [58].
The influence of alcohol has also been studied. Comparing the use of
ethanol versus methanol, Meneghetti et al. have found that similar
yields of fatty acid esters may be obtained; however, the reaction with
methanolysis is much more rapid [59]. Cvengros et al. produced both
ethyl and methyl esters, using NaOH in the presence of ethanol and
methanol, respectively. Despite the high viscosity and density values,
they concluded that both methyl and ethyl esters can be successfully
used as fuel. A positive solution to meet the standard values for both
viscosity and density parameters can be a dilution with esters based