Rhenium - Re

Rhenium — chemical properties and water context

Rhenium is a rare, silvery transition metal with a very high melting point. Its water-treatment relevance is mainly in specialized process streams from ore processing and metal refining.

Atomic number	75
Standard atomic weight	186.207 g/mol
Density	20.8 g/cm³
Melting point	3185 °C
Boiling point	5590 °C
Electron configuration	[Xe] 4f¹⁴ 5d⁵ 6s²

Chemical properties

Rhenium is in Group 7 and Period 6. It is dense, has a high melting point and occurs in trace amounts in some molybdenum and copper ores. In oxygenated aqueous systems, it may occur as perrhenate (ReO₄⁻), a dissolved oxyanion; its concentration and behaviour depend on source and water chemistry.

Uses and applications

Rhenium is added to nickel-based superalloys and tungsten- or molybdenum-based alloys for high-temperature service. It is also used in some catalysts and electrical contacts. Much rhenium is recovered as a by-product of processing other metal ores.

Rhenium in water treatment

Where rhenium is present in mining or refining water, identify whether it occurs as dissolved perrhenate or in suspended solids. Ion-exchange and sorption approaches have been studied for perrhenate capture and rhenium recovery, but selection depends on competing anions, acidity and concentration. Characterize and test the actual stream before design.

Environmental and health context

Rhenium occurs at very low levels in the Earth's crust, and its environmental behaviour is less documented than that of common water contaminants. A detected concentration should be interpreted in relation to the industrial source, chemical form and analytical method.