Ferrous sulfate

Ferrous sulfate (CAS 7720-78-7) is an inorganic iron salt in heptahydrate or anhydrous form.

Where is Ferrous sulfate used?

• Water treatment: coagulant and phosphate precipitant
• Pharmaceuticals: active iron source in oral iron-deficiency supplements and fortified foods
• Agriculture: corrects iron chlorosis in soils and turf; moss control in lawn care
• Mining: hydrometallurgical precipitation of metals from leach solutions
• It also acts as a reducing agent in chromate treatment of effluent.
• Reduces hexavalent chromium (chromate) in cement to trivalent chromium.
• Feed additive in animal nutrition, especially for pigs and poultry, as an iron source for hemoglobin formation.
• Biogas industry: additive to optimize fermentation of organic substances by binding hydrogen sulfide.
• Raw material in the production of iron oxide pigments.

Good to know: Recognized grades include USP, BP, and food-grade (FCC), alongside technical and agricultural grades.

Formulation notes

• The heptahydrate form contains 19–21% iron, while the monohydrate form contains about 29–30% iron.
• The use rate of ferrous sulfate heptahydrate in iron-containing formulations must be determined technically according to plant species, soil pH, application method, target iron value and compatibility with other components.
• Heating releases toxic sulfur oxide gas.
• Has higher reducing capability than sodium metabisulfite.

Typical specification

• Ferrous sulfate heptahydrate has a solubility in water of 29.51 g/100 ml at 25 °C and 51.35 g/100 ml at 54 °C.
• The cerimetric assay content of ferrous sulfate heptahydrate is 98.0–105.0%.
• Most commonly available as the monohydrate and the heptahydrate.
• Dried ferrous sulfate typically appears as a light grey to beige powder with good flow properties and high stability under recommended storage conditions.

Regulatory status

• Ferrous sulfate heptahydrate has customs tariff code 2833 29 80 80.
• EU Directive 2003/53/EC requires all EU member states to keep chromium content in cement or cement-containing preparations below 2 mg/kg since 17 January 2005.

Storage, packaging and handling

• Ferrous sulfate heptahydrate should be stored in a cool, ventilated and moisture-free environment in closed packaging.
• In humid environments, ferrous sulfate is coated with ferric sulfate, giving a brown appearance.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.