Vanadium
Vanadium is a rare, soft, ductile gray-white element found combined in certain minerals and used mainly to produce certain alloys. Vanadium resists corrosion due to a protective film of oxide on the surface. Common oxidation states of vanadium include +2, +3, +4 and +5.
Applications
Most of the
vanadium (about 80%) produced is used as ferrovanadium or as a steel
additive. Mixed with aluminium in titanium alloys
is used in jet engines and high speed air-frames, and steel alloys are used
in axles, crankshafts, gears and other critical components. Vanadium alloys
are also used in nuclear reactors because vanadium has low neutron-adsorption
abilities and it doesn not deform in creeping under
high temperatures.
Vanadium
oxide (V2O5) is used as a catalyst in manufacturing
sulfuric acid and maleic anhydride and in making
ceramics. It is added to glass to produce green or blue tint. Glass coated
with vanadium dioxide (VO2) can block infrared radiation at some
specific temperature.
Vanadium
in the environment
Vanadium is
never found unbound in nature. Vanadium occurs in about 65 different minerals
among which are patronite,
vanadinite, carnotite and
bauxite. Vanadium occurs in carbon containing deposits such as crude oil,
coal, oil shale and tar sands.
Various vanadium ores are known but none is mined as such for the metal,
which is generally obtained as a byproducts of other
ores. The largest resources of vanadium are to be found in
Watering is an important way in which vanadium is redistributed around the
environment because venedates are generally very
soluble.
Vanadium is
abundant in most soils, in variable amounts, and it is taken up by plants at
levels that reflect its availability.
In biology,
a vanadium atom is an essential component of some enzymes, particularly the
vanadium nitrogenase used by some nitrogen-fixing
microorganisms.
Health effects of vanadium
Vanadium compounds are not regarded as
serious hazard, however, workers exposed to vanadium peroxide dust were
found to suffer severe eye, nose and throat irritation.
The uptake of vanadium by humans mainly
takes place through foodstuffs, such as buckwheat, soya
beans, olive oil, sunflower oil, apples and eggs.
Vanadium can have a number of effects on human health, when the uptake is
too high. When vanadium uptake takes places through air it can cause
bronchitis and pneumonia.
The acute effects of vanadium are irritation of lungs, throat, eyes and
nasal cavities.
Other health effects of vanadium uptake are:
- Cardiac and vascular disease
- Inflammation of stomach and intestines
- Damage to the nervous system
- Bleeding of livers and kidneys
- Skin rashes
- Severe trembling and paralyses
- Nose bleeds and throat pains
- Weakening
- Sickness and headaches
- Dizziness
- Behavioural changes
The health
hazards associated with exposure to vanadium are dependent on its oxidation
state. This product contains elemental vanadium. Elemental vanadium could
be oxidized to
vanadium pentoxide
during welding. The pentoxide form is more toxic
than
the elemental form.
Chronic exposure to vanadium pentoxide dust and
fumes may cause severe irritation
of the eyes, skin, upper respiratory tract,
persistent inflammations of
the trachea and bronchi, pulmonary edema, and systemic poisoning. Signs and
symptoms of overexposure include;
conjunctivitis, nasopharyngitis,
cough, labored breathing, rapid heart beat,
lung changes, chronic
bronchitis, skin pallor, greenish-black tongue and an
allergic
skin rash.
Effects of vanadium on the environment
Vanadium can be found in the environment in
algae, plants, invertebrates, fishes and many other species. In mussels and
crabs vanadium strongly bioaccumulates, which can
lead to concentrations of about 105 to 106 times
greater than the concentrations that are found in seawater.
Vanadium
causes the inhibition of certain enzymes with animals, which has several
neurological effects. Next to the neurological effects vanadium can cause
breathing disorders, paralyses and negative effects on the liver and
kidneys.
Laboratory
tests with test animals have shown, that vanadium
can cause harm to the reproductive system of male animals, and that it
accumulates in the female placenta.
Vanadium
can cause DNA alteration in some cases, but it cannot cause cancer with
animals.