ferriksulfat

Ferriksulfat, also known as ferric sulfate or iron(III) sulfate, is an inorganic salt with the formula Fe2(SO4)3. In solid form it is typically encountered as hydrates, since the anhydrous salt is highly hygroscopic and readily absorbs moisture from the air. In aqueous solution, iron(III) sulfate produces strongly acidic conditions and ferric ions that undergo hydrolysis to various species, eventually leading to precipitates such as iron oxyhydroxide on aging.

Production and occurrence

Ferric sulfate is produced by reacting sulfuric acid with iron(III) oxide or hydrated iron oxides: Fe2O3 + 3 H2SO4 → Fe2(SO4)3 + 3 H2O. It can also be formed by oxidation of ferrous sulfate in acidic, sulfate-rich media to ferric sulfate. Pure, anhydrous Fe2(SO4)3 is uncommon; commercial material is typically a hydrated salt and is often handled in solution or as a solid hydrate.

Uses

Ferric sulfate is widely used as a coagulant and flocculant in drinking water and wastewater treatment, aiding the removal of suspended solids, color, and phosphorus. It is also used as a mordant and pigment in textiles and paper industries, and in some mineral processing operations to precipitate contaminants.

Safety and handling

Ferric sulfate solutions are highly acidic and corrosive. They can cause skin and eye irritation and may damage metals. Proper PPE (gloves, eye protection) and engineering controls are recommended. The solid and concentrated solutions should be stored in corrosion-resistant containers, away from moisture and incompatible materials.

See also

Iron(II) sulfate (ferrous sulfate) and iron(III) oxide as related iron-containing species and their reactions with sulfuric acid.