Ferrous Sulfate Heptahydrate (FeSO₄·7H₂O) 7782-63-0

Ferrous Sulfate Heptahydrate (FeSO₄·7H₂O) is a blue-green crystalline solid with a molecular weight of 278.01 g/mol. It contains approximately 19-20% iron and is the most common hydrated form of ferrous sulfate. It is obtained primarily as a byproduct of titanium dioxide production or from steel pickling operations.

Ferrous sulfate heptahydrate (FeSO₄·7H₂O) contains seven water molecules and has 19-20% iron content with rapid dissolution. Ferrous sulfate monohydrate (FeSO₄·H₂O) contains one water molecule and has 30% iron content with better storage stability. Heptahydrate is preferred for liquid dosing and water treatment where fast dissolution matters, while monohydrate is preferred for feed and dry applications where higher iron content is required.

In water treatment, ferrous sulfate heptahydrate serves as a coagulant for phosphate removal and heavy metal precipitation. The ferrous iron oxidizes to ferric iron in aerated water, forming iron hydroxide flocs that adsorb and settle out contaminants. It also acts as a sludge conditioner to improve dewatering characteristics. The heptahydrate form is preferred for liquid dosing systems due to its rapid dissolution.

Ferrous sulfate heptahydrate is used in agriculture as a soil amendment to correct iron chlorosis (yellowing of leaves due to iron deficiency) in crops, ornamental plants, and turf. It is also an effective moss killer for lawns when applied as a solution or granular treatment. It can be applied directly to soil or as a foliar spray to provide readily available iron to plants.

Ferrous sulfate heptahydrate should be stored in a cool, dry, well-ventilated area in tightly sealed containers away from moisture and direct sunlight. The product can effloresce and lose crystal water in dry air, or oxidize to brown ferric sulfate when exposed to moist air. Under proper storage conditions, shelf life is 12 months. Keep containers sealed when not in use to maintain product quality.