ABSTRACT

Vanadium is a widely dispersed element that is found in about 65 minerals and generally occurs in low concentrations. Making up about 0.014% of the Earth’s crust, it is the fifth-most abundant transition metal. It can be found in deposits with ores of other metals, particularly with a titanium iron magnetite ore and with the uranium ore, carnotite. Relatively high concentrations are found in certain oil and coal deposits, and consequently, they present a significant pollution hazard when such deposits are exploited. In particular, ash from gas-and oil-burning equipment often contains more than 10% vanadium. It is also found at rather high concentrations in some freshwaters and is listed as a metal of concern by the U.S. Environmental Protection Agency. It is found in ocean waters at concentrations of about 30 nmol/L, a value that varies considerably, dependent on region. Vanadium in the metallic state is used, along with other metals, as an additive to iron to form various stainless steels and is a component of some superconducting alloys. Also, it catalyzes the disproportionation of CO to C and CO

. The vanadium oxide, V

O

, is a powerful and versatile catalyst that is used extensively in industrial processes and finding recent application in nanomaterials, whereas peroxovanadates are useful oxidants often used in organic synthesis and found in naturally occurring enzymes, the vanadium-dependent haloperoxidases.