- Possibly used to make Wootz steel and Damascus steel.

History

Vanadium (named after Vanadis, another name for Freyja|Freya, the Scandinavian goddess of fertility) was originally discovery of the chemical elements|discovered by Andrés Manuel del Río (a Spanish-born Mexican mineralogist) in Mexico City, in 1801. He discovered the element after being sent a sample of "brown lead" ore (now named vanadinite). Through experimentation, he found it to form salts with a wide variety of colors, so he named the element panchromium (Greek: all colors). He later renamed this compound erythronium, since most of the salts turned red when heated. The French chemist Hippolyte Victor Collet-Descotils incorrectly declared that del Río's new element was only impure chromium. Del Río thought himself to be mistaken and accepted the statement of the French chemist that was also backed by del Río's friend Baron Alexander von Humboldt. In 1831, Nils Gabriel Sefström|Sefström of Sweden rediscovered vanadium in a new oxide he found while working with some iron ores and later that same year Friedrich Wöhler confirmed del Río's earlier work. Later, George William Featherstonhaugh, one of the first US geologists, suggested that the element should be named "rionium" after del Río, but this never happened. Metallic vanadium was isolated by Henry Enfield Roscoe in 1867, who reduced vanadium(III) chloride VCl₃ with hydrogen. The name vanadium comes from Vanadis, a goddess in Scandinavian mythology, because the element has beautiful multicolored chemical compounds. Vanadium is mined mostly in South Africa, Namibia, Botswana, Zimbabwe, Zambia, north west China, the Great Plains of USA, eastern Russia and Kazakhstan.

Biological role

In biology, a vanadium atom is an essential component of some enzymes, particularly the vanadium nitrogenase used by some nitrogen fixation|nitrogen-fixing micro-organisms. Vanadium is essential to ascidiacea|ascidians or Tunicate|sea squirts in Vanabins|vanadium chromagen proteins. The concentration of vanadium in their blood is more than 100 times higher than the concentration of vanadium in the seawater around them. Rats and chickens are also known to require vanadium in very small amounts and deficiencies result in reduced growth and impaired reproduction. Ten percent of the blood cell pigment of the sea cucumber is vanadium. Just as the horseshoe crab has blue blood rather than red blood cell|red blood (colored by iron in hemoglobin) because of copper in the hemocyanin pigment, the blood of the sea cucumber is yellow because of the vanadium in the vanabins|vanabin pigment. Nonetheless, there is no evidence that vanabins carry oxygen, in contrast to hemoglobin and hemocyanin. A form of vanadium, vanadyl sulfate, seems to improve glucose control in people with type 2 diabetes. Several species of macrofungi, namely ''Amanita muscaria'' and related species, are known as effective accumulators of vanadium (up to 500 mg/kg in dry weight). Vanadium is present as an organometallic compound (called amavadine) in fungal fruit-bodies. However, the biological importance of the accumulation process is unknown.

Mineral supplement in drinking water

Most continental waters show a vanadium concentration of less than 3 ppb. However, the groundwater of Mt. Fuji contains a very high concentration of vanadium—up to 150 ppb. This vanadium is solubilized from the basalt by the groundwater. The vanadium content in Mt. Fuji becomes higher at places nearer the summit and deeper in the ground. Recently this high-vanadium water of Mt. Fuji has been sold by many companies as an agent to cope with diabetes. However, there is no concrete evidence for its efficacy. The rainbow trout living in the Mt. Fuji water showed much higher accumulation of vanadium in kidneys and bone.

Occurrence

Vanadium is never found unbound in nature but it does occur in about 65 different minerals among which are patronite VS₄, vanadinite Pb₅(VO₄)₃Cl, and carnotite K₂(UO₂)₂(VO₄)₂.3H₂O. By far the greatest proportion of the world's vanadium production is sourced from vanadium-bearing magnetite found in ultramafic gabbro bodies. From these ores vanadium can be calcined to form ferrovanadium, or can be recovered from the vanadium steel smelting process which is widely used in Russia and China. Vanadium is also present in bauxite, and in carbon containing deposits such as crude oil, coal, oil shale and tar sands. Vanadium has also been detected spectroscopically in light from the Sun and some other stars. Much of the vanadium metal being produced is now made by calcium reduction of Vanadium(V) oxide|V₂O₅ in a pressure vessel. Vanadium is usually recovered as a by-product or co-product, and so world resources of the element are not really indicative of available supply.
- ''See also :category:vanadate minerals.''

Isolation

Vanadium is available commercially and production of a sample in the laboratory is not normally required. Commercially, routes leading to metallic vanadium as main product are not usually required as enough is produced as byproduct in other processes. In industry, heating of vanadium ore or residues from other processes with sodium chloride|salt NaCl or sodium carbonate Na₂CO₃ at about 850°C gives sodium metavanadate|sodium vanadate NaVO₃. This is dissolved in water and acidified to give a red solid which in turn is melted to form a crude form of vanadium pentoxide V₂O₅. Reduction of vanadium pentoxide with calcium gives pure vanadium. An alternative suitable for small scales is the reduction of vanadium pentachloride VCl₅ with hydrogen or magnesium. Many other methods are also in use. Industrially, most vanadium is used as an additive to improve steels. Rather than proceed via pure vanadium metal it is often sufficient to react the crude of vanadium pentoxide V₂O₅ with crude iron. This produces ferrovanadium suitable for further work.

Compounds

Vanadium(V) oxide|Vanadium pentoxide V₂O₅ is used as a catalyst principally in the production of sulfuric acid. It is the source of vanadium used in the manufacture of ferrovanadium. It can be used as a dye and color-fixer. Vanadyl sulfate VOSO₄, also called vanadium(IV) sulfate oxide hydrate, is used as a relatively controversial dietary supplement, primarily for increasing insulin sensitivity and body-building. Whether it works for the latter purpose has not been proven, and there is some evidence that athletes who take it are merely experiencing a placebo effect. Anhydrous VCl₄ is a liquid at room temperature and reacts violently with water; it can be used, in conjunction with an appropriate nitrogen compound, for vapour deposition of hard VN layers http://www3.interscience.wiley.com/cgi-bin/abstract/109609704/ABSTRACT. Vanadium pentafluoride is an extremely powerful fluorinating agent, capable of perfluorinating chloroalkanes http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGD-4D5KSCG-1&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0e95853a43997369cb00b05980e7f894, and has been proposed (eg http://www.isrd.tpu.ru/english/orion/html/11-2.htm) as a safe and economical substitute for XeF₂(Xenon difluoride)); it is also liquid at room temperature. Sodium orthovanadate|Orthovanadate VO₄^3- is used in biochemistry as a phosphate analogue; in protein crystallography it can be used to make phosphate binding sites very visible in electron density. Vanadium forms polyoxometalate cluster compounds, including V₁₀ O₂₄.

Toxicity of vanadium compounds

The toxicity of vanadium depends on its physico-chemical state; particularly on its valence state and solubility. Tetravalent VOSO₄ has been reported to be more than 5 times as toxic as trivalent V₂O₃ (Roschin, 1967). Vanadium compounds are poorly absorbed through the gastrointestinal system. Inhalation exposures to vanadium and vanadium compounds result primarily in adverse effects to the respiratory system (Sax, 1984; ATSDR, 1990; Ress et al., 2003; Worle-Knirsch et al., 2007). Quantitative data are, however, insufficient to derive a subchronic or chronic inhalation reference dose. Other effects have been reported on blood parameters after oral or inhalation exposures (Scibior et al., 2006; Gonzalez-Villalva et al., 2006), on liver (Kobayashi et al., 2006), neurological development in rats (Soaso and Garcia, 2007), and other organs. There is little evidence that vanadium or vanadium compounds are reproductive toxins or teratogens. Vanadium pentoxide was reported to be carcinogenic in male rats and male and female mice by inhalation in an NTP study (Ress et al., 2003), although the interpretation of the results has recently been disputed (Duffus, 2007). Vanadium has not been classified as to carcinogenicity by the U.S. EPA (1991a).

Various oxidation states of vanadium ions

It is known that vanadium gets the oxidation states +2, +3, +4, +5. To observe the colors of these states, ammonium metavanadate (NH₄VO₃) can be used as a starting agent. It must be acidified beforehand so dioxovanadium(V) ion, VO₂⁺ (yellow +5 oxidation number) is produced. In alkaline medium, the stable form of vanadium(V) state is VO₃^-. Adding zinc powder and concentrated hydrochloric acid continuously, VO₂⁺ is reduced into blue VO²⁺. It can be seen that during the reaction, the mixture is green in colour as the original yellow of the +5 state and the blue of the +4 are present. Continuously adding Zn powder and concentrated HCl, blue VO²⁺ is reduced to green V³⁺. V³⁺ is then reduced to violet V²⁺ by Zn powder and concentrated HCl again.
- ''See also :category:vanadium compounds|Vanadium compounds.''
- ''See also Vanadium(V) oxide.''

Isotopes

Naturally occurring vanadium is composed of one stable isotope ⁵¹V and one radioactive isotope ⁵⁰V with a half-life of 1.5×10¹⁷ years. 24 artificial radioisotopes have been characterized (in the range of mass number between 40 and 65) with the most stable being ⁴⁹V with a half-life of 330 days, and ⁴⁸V with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lives shorter than an hour, the majority of them below 10 seconds. In 4 isotopes, nuclear isomer|metastable excited states were found (including 2 metastable states for ⁶⁰V). The primary decay mode before the most abundant stable isotope ⁵¹V is electron capture. The next most common mode is beta decay. The primary decay products before ⁵¹V are element 22 (titanium) isotopes and the primary products after are element 24 (chromium) isotopes.

Precautions

Powdered metallic vanadium is a fire hazard, and unless known otherwise, all vanadium compounds should be considered highly toxic. Generally, the higher the oxidation state of vanadium, the more toxic the compound is. The most dangerous compound is vanadium pentoxide. The Occupational Safety and Health Administration (OSHA) has set an exposure limit of 0.05 mg/m³ for vanadium pentoxide dust and 0.1 mg/m³ for vanadium pentoxide fumes in workplace air for an 8-hour workday, 40-hour work week. The National Institute for Occupational Safety and Health (NIOSH) has recommended that 35 mg/m³ of vanadium be considered immediately dangerous to life and health. This is the exposure level of a chemical that is likely to cause permanent health problems or death.

See also

- :category:vanadium compounds|Vanadium compounds
- :category:vanadium minerals|Vanadium minerals
- :category:vanadate minerals|Vanadate minerals

Footnotes

References

- Los Alamos National Laboratory – Vanadium
- ''High vanadium content in Mt.Fuji groundwater and its relevance to the ancient biosphere by Tatsuo Hamada in Vanadium in Environment. Part 1: Chemistry and Biochemistry. Edited by Jerome O. Nriagu. Page 97-123. 1998. John Wilen & Sons, Inc.'' * * * * * * *

External links

- WebElements.com – Vanadium
- Mineral Information Institute – Vanadium
- ATSDR – ToxFAQs: Vanadium
- The Vanadium Redox Battery was invented at The University of New South Wales
- Vanadium general infos
- Oxidation States of Vanadium, with video demostration and electrode potentials relevant
- Redox chemistry quoted Vanadium as illustrations
- The (REACH) Vanadium Consortium
- Comprehensive Data on Vanadium Category:Chemical elements Category:Dietary minerals Category:Transition metals Category:Vanadium simple:Vanadium

Related Images

- Vanadinite

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