Potassium ferrate is the chemical compound with the formula K2FeO4. This purple salt is paramagnetic, and is a rare example of an iron(VI) compound.


Molecular formula K2FeO4
Molar mass 198.0392 g/mol
Appearance Dark purple solid
Tablet size:0.5-5gram
Active Ingredient:3%-15%
Density 2.829 g/cm3, solid
Melting point >198 °C (decomposition temp)
Main hazards oxidizer
Flash point non-combustible


K2FeO4 has attracted interest for applications in "green chemistry" because the by-products of its use, iron oxides, are environmentally innocuous. In contrast, some related oxidants such as chromate are considered environmentally hazardous. However, the main difficulty with the use of K2FeO4 is that it is often too reactive, as indicated by the fact that it decomposes in contact with water.


Properties and applications
As a dry solid, K2FeO4 is stable. It decomposes with evolution of O2 in neutral water, and especially rapidly in acidic water. At high pH, aqueous solutions are stable. The deep purple solutions are similar in appearance to potassium permanganate (KMnO4). It is stronger oxidizing agent than the latter.

Because the side products of its redox reactions are rust-like iron oxides, K2FeO4 has been described as a "green oxidant." It has been employed in waste-water treatment as an oxidant for organic contaminants and as a biocide. Conveniently, the resulting reaction product is iron(III) oxyhydroxide, an excellent flocculant.