The ferric chloride test is a traditional colorimetric test for phenols, which uses a 1% iron(III) chloride solution that has been neutralised with sodium hydroxide until a slight precipitate of FeO(OH) is formed. The mixture is filtered before use. Ferric chloride solution is a colorless to light brown aqueous solution that has a faint hydrochloric acid odor. Highly corrosive to most metals and probably corrosive to tissue. Noncombustible. Used in sewage treatment and water purification.
Ferric chloride is a brownish liquid which has a pungent odor which is similar to that of hydrochloric acid. It also exists in solid lump form or in anhydrous powder form. Ferric Chloride or Iron (III) Chloride is used as a flocking agent in drinking water and waste water treatment in various industries. When small amount of ferric chloride is added in water, ferric hydroxide precipitates and absorbs the suspended impurities. Ferric chloride is generally used as a concentrated solution with minimum concentration of 40% w/w. Moreover in few industrial applications, ferric chloride is also used in crystalline solid form. Aqueous ferric chloride solution is acidic in nature and corrosive to most metals. Ferric chloride is most commonly produced from chlorine gas and pickling liquors. Moreover, ferric chloride produced as a byproduct of manufacturing titanium dioxide is also used in many industries.
Consumption in the United States is forecast to grow at 1.3% annually during 2016-21. Ferric chloride producers tend to have a regional, rather than a national outlook, because transportation costs are significant. More than 80% of all ferric chloride is sold in municipal bids, with 53% sold for municipal wastewater applications, and 37% for potable water treatment applications. Industrial water treatment applications account for 6% of consumption, with the remaining 5% sold in nonwater treatment applications, such as electronic and photographic etchants, metal surface treatment, and as a catalyst. Much of the etchant activity has moved to Asia.