Potassium ferrocyanide

Potassium ferrocyanide (CAS 13943-58-3), also known commercially as E536 and tetrapotassium hexacyanoferrate, is an inorganic iron-cyanide salt used across food processing, metal treatment, and industrial separation processes. It functions primarily as an anti-caking agent, chelating agent, and selective precipitant depending on the application sector. In food production, E536 is approved as an anti-caking additive in table salt and salt substitutes.

This additive prevents clumping during storage and packaging. Metal processing operations use it to selectively precipitate heavy metals, particularly copper and zinc, from process streams and wastewater, supporting both recovery and effluent compliance. In winemaking, it is applied as a fining agent to remove excess copper and iron ions that would otherwise cause haze or off-flavors. Textile and leather dyeing processes rely on it as a reducing auxiliary and fixative.

It is also used in blue pigment formulations, including Prussian blue production. Potassium ferrocyanide is supplied as a yellow crystalline powder or granules. Food-grade material is available to E536 specification. This material meets purity requirements for use in edible salt applications. Technical grade is supplied for industrial water treatment, mining, and dyeing applications where food compliance is not required.