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Vanadium
     

Vanadium, also: Vanadin (der. old nordic: Vanadis [name of the Germanic goddess of beauty, Freya; due to the beautifully multicolored appearance of some V compounds]) is a chemical element in the periodic table of the elements, with the symbol V and the atomic number 23. It is a rare, soft, and ductile element.

Properties

Vanadium is an unmagnetic, ductile, molleable and silvery-lustrous transition metal. It has good resistance to corrosion. It has good resistance to alkalis as well as to sulfuric and hydrochloric acid. It oxidizes at about 933 K (660°C) to vanadium pentoxide V 2 O 5.
Vanadium has good structural strength.

As a chemical compound, vanadium usually has the oxidation state of +5. Common oxidation states of vanadium also include +2, +3, +4; in these oxidation states, however, vanadium tends to change to the state of +5. Vanadium(II) and vanadium(III)oxides react basic, vanadium(IV) oxide amphoteric and vanadium(V) oxide acidic.

A popular experiment to demonstrate these vanadium oxidation states colorimetrically is the reduction of colorless ammonium vanadate ( N H 4 V O 3 ) with zinc metal. Consecutively, they form blue V(IV), green V(III) and pale-violet V(II) saline solutions. The lower vanadium valencies oxidize by air and reform to vanadium(V). Due to this property to quickly change its valancies, vanadium is also used as a catalyst. The oxidation state +1 is rarely seen. The oxidation states of 0, -1 and -3 are possible as well.

Applications

Approximately 80% of the vanadium produced is distributed as ferrovanadium or used as an alloy additive in steel production. Hard and resistant vanadium steels rarely contain more than 1% of vanadium.

  • Specialty stainless steels for use in surgical instruments and tools
  • rust-resistant and high-speed tool steels)
  • mixed with aluminum in titanium alloys used in jet engines and high-speed aircrafts
  • Vanadium steel alloys are used in axles, crankshafts, gears, and other critical components
  • Carbide stabilizer in steel production.
  • Vanadium foil is used as a buffer in plating titanium to steel.
  • Vanadium-gallium tape is used in the production of superconducting magnets with a flux density of 175,000 gauss
  • Vanadium compounds are used as catalysts in producing maleic anhydride and sulfuric acid
  • Vanadium pentoxide (V 2 O 5 ) is used in making ceramics and as a catalyst
  • Vanadium alloys might also be used in fusion power plants in the future.

History

Vanadium was originally discovered by Andrés Manuel del Río in 1801, a Spanish mineralogist, who found the mineral in a lead ore, vanadinite (lead vanadite), in Mexico City,and who called it "brown lead". Due to the chromium-like color of the element compounds, he named the new element panchromium. Later del Rio renamed this compound erythronium (Greek: red) since it mostly turned red when heated.

French chemists could convince del Rio that "brown lead" was a basic lead chromate, and that therefore erythronium was only impure chromium. Del Rio accepted this statement and his discovery fell into oblivion. In 1831, Nils Gabriel Sefström of Sweden rediscovered vanadium while working with iron ores. Later that same year Friedrich Wöhler confirmed del Rio's earlier work. Metallic vanadium was isolated in 1867 by Henry Enfield Roscoe, who reduced vanadine(III) chloride with hydrogen.

Vanadium compounds are beautifully multicolored. Therefore Sefström named it after Freya, the Nordic beauty goddess, whose sobriquet was Vanadis.

Physiology

In biology, vanadium is an essential component of some enzymes. Vanadium nitrogenase? is used by some nitrogen-fixing microorganisms.

Rats and chickens are also known to require vanadium in very small quantities. Vanadium deficiencies in rats and chickens result in reduced growth and impaired reproduction.

Vanadations VO 4 3- have an effect similar to insulin. However, the necessary dose rates are toxic. The body cannot retain enough of the significantly less toxic vanadylion VO 2+, though. Organic vanadyl complexes are promising.

Deposits

Vanadium is never found unbound in nature. It occurs in about 65 minerals.

   * Patronite VS 4
   * Vanadinite [Pb 5 (VO 4 )3Cl]
   * Carnotite [K 2 (UO 2 ) 2 (VO 4 ) 2 .3H 2 O]
   * Descloizite Pb(Zn, Cu) [OH|VO 4 ]
   * as a contamination in magnetite, an iron ore that can contain up to 1-2% of vanadium.

Vanadium is present in bauxite as well as in fossil fuels such as crude oil, carbon, oil shale, and tar sands. Vanadium has also been detected spectroscopically in the light of the Sun and some other stars.

It has also been detected in Amanita Muscaria (fly agaric).

Its biggest deposits are in South Africa, Russia, Australia, USA and Finland.

Production

Reducing vanadium pentoxide V 2 O 5 with calcium under high pressure gives metallic vanadium. Vanadium is often produced as by-product or joint product (e.g. processing petroleum?, uranium ore extraction? etc.).