Water and wastewater treatment (coagulant for removing impurities and phosphates). Etching agent for metals (e.g. printed circuit boards). Catalyst in organic synthesis. Pigment and dye production.

Mainly used as a coagulant and catalyst in water treatment and industrial chemical processes.

Highly water-soluble. Hygroscopic (absorbs moisture from air). Acidic and corrosive. Strong oxidizing agent in some reactions. Can corrode metals like copper and steel in moist conditions.