Ferric chloride is mainly used in industries for purifying water and wastewater treatment. It is also largely used in the production of printed circuit boards as an etching medium and in indigo blue dyestuff production as an oxidant. In the laboratory, ferric chloride is commonly used as a Lewis acid for catalyzing reactions, such as Friedel-Crafts reaction of aromatics and chlorination of aromatic compounds.
Ferric chloride, also called iron chloride, is a chemical compound with a chemical formula of FeCl3. It has a relatively low melting point, and its boiling temperature is around 315 degrees Celsius. When dissolved in water, ferric chloride undergoes hydrolysis and gives off heat in an exothermic reaction. It is produced industrially by the reaction of dry chlorine with scrap iron at 500 to 700 degrees Celsius.
In water and wastewater treatment operations, ferric chloride is used as coagulants or flocculants for odor control, phosphorus removal and hydrogen sulphide minimization. This is one of the few water treatment chemicals that can sequester odors. In the U.S., more than 80 percent of all ferric chloride is sold in municipal bids, with 65 percent sold for municipal wastewater applications, and 18 percent for potable water treatment applications.