Widely used as a coagulant in water and wastewater treatment to remove suspended solids, phosphates, and other impurities. It helps clarify water by forming flocs that settle easily. Commonly applied in municipal sewage treatment and industrial effluent processing. Used in the production of printed circuit boards (PCBs) for etching copper due to its ability to oxidize and dissolve metal layers. Offers precise control in etching processes and is cost-effective for small-scale operations. Acts as a catalyst in organic synthesis, particularly in Friedel-Crafts reactions and chlorination processes. Also employed in the pulp and paper industry for sludge dewatering and pitch control. Utilized in odor control systems where it reacts with hydrogen sulfide to form insoluble iron sulfides, reducing foul smells in sewer systems and treatment plants.