Environmental Engineering Reference
In-Depth Information
latitudes between 10° and 65°, both north and south. Its cultivation is confined to low elevations, but
it can be successfully grown up to 770 m. Areas with an annual rainfall ranging from 45 to 75 cm
are best suited for its cultivation. The seed crop does well under moderate cold, but the fiber crop
grows best in cool moist climates. Linseed can be grown on different kinds of soils, except sandy
and badly drained heavy clays or clay loams. It does well on the deep clayey black soils of central
and peninsular India and on the alluvium loams of the Indo-Gangetic plains. The main season for
sowing linseed is October to November, depending upon the cessation of the rains. The linseed crop
starts maturing by mid-February, depending on winter spread and sowing time. Plants turn golden
yellow when the crop is mature and ready for harvesting. Harvesting is done when the crop is dead
ripe with a sickle or by uprooting the plants. The average yield of a pure crop varies from 210 to
450 kg/ha of seed under rain-fed cultivation. The crop in northern India generally gives a higher
yield than in central and peninsular India. The irrigated crop may yield 1200-1500 kg/ha.
Oil content of the seed is 35-45%. Crude linseed oil has a dark amber color and a strong, char-
acteristic odor. Linseed oil is exclusively used as nonedible oil, principally in the manufacture of
paints and varnishes, linoleum, oilcloth, and printing ink. India is the third-largest producer of lin-
seed in the world. Indian linseed is mainly cultivated as a rabi seasonal crop with October through
November being the main sowing season. February through April is the main harvesting season.
The oil cake left after the oil is pressed out is a most valuable feeding cake, perhaps the most
favorite cattle feed. It is good in taste and contains 36% protein, 85% of which is digestible. It is
fed to fattening animals. It is also used as organic manure. It contains approximately 5% nitrogen,
1.4% phosphorus, and 1.8% potash. Straw from seed varieties are used in the manufacturer of
upholstery, insulating material, rugs, twine, and paper. India accounts for approximately 1.9 million
ha, with a seed production of 0.498 million t, and is third among linseed-producing countries. India
averages 255 kg/ha.
25.1.2.5 rubberseed oil (
hevea brasiliensis
muell arg)
The botanical name of the rubber tree is
Hevea brasiliensis
(Euphporbiaceae). The tree is medium
sized, up to 18 m in height, drought-resistant, tolerant of salinity, grows fast, and matures after 4-7
years. In India it is widely grown in the southern states of Kerala, Tamil Nadu, and Karnataka.
Rubber seed kernels (50-60% of seed) contain 40-50% of the brown-colored oil. The estimated
availability of rubber seeds in India is approximately 30,000 t/year, which can yield approximately
5000 t of rubber seed oil. Rubber trees yield a three-seeded ellipsoidal capsule, each capsule with
one seed. Rubber seeds are ellipsoidal, approximately 2.5-3 cm long, mottled brown, lustrous, and
weigh 2-4 g each. Fresh oil is pale yellow, but commercial oil is dark in color. It is a semidrying
oil used in surface coatings for making alkyl resins. It is a partial substitute for linseed oil in paints
and varnishes. It is effective against house flies and lice and is used up to 30% in soap making.
Commercial oil contains fatty acids.
The rubber seed production in India is approximately 150 kg/
ha per year. The estimated availability of rubber seed is approximately 30,000 Mt/year. At present,
rubber seed oil has not found any major application and hence the natural production of seeds
remains underutilized.
25.2 BIodIesel PreParatIon
Transesterification is a process of producing a reaction in a triglyceride and alcohol in the presence
of a catalyst to produce glycerol and ester. The molecular weight of a typical ester molecule is roughly
one-third that of a typical oil molecule and, therefore, it has a much lower viscosity. A catalyst is
used to increase the reaction rate and yield. Because the reaction is reversible, excess alcohol is
used to shift the equilibrium to the product side. Alcohols are primary and secondary monohydric
aliphatic alcohols having one to eight carbon atoms. Among the alcohols that can be used in the
transesterification process, methanol and ethanol are more common. Methanol is used extensively
because of its low cost and its physicochemical advantages such as polarity and easy solubility
