What is Ferric Sulphate and How is It Prepared?

Ferric sulphate is an inorganic chemical compound that is used for increasing the rate of sedimentation in wastewater cleaning processes. With a pH of less than two, this compound is highly corrosive and should not be touched with bare skin. It is also known by many synonyms including Combiron, Copperas, Ferobuff, Ferric Persulfate, green salts, and Slow Fe. It is made by treating ferrous sulfate with an oxidizing agent.

The chemical compound is written out as Fe2(SO4)3, which means it contains a total of three naturally occurring chemical elements. Ferric sulphate is supplied as a reddish brown liquid manufactured from mined magnetic iron ore, virgin sulfuric acid, liquid oxygen, and water. Before use in its myriad industrial applications, the solution is prepared through oxidation, converting the ferrous iron within its composition into ferric iron. Stable iron concentrations in the resulting compound run up to 14%. The resulting solution can also be converted into granular form.

Ferric sulphate should be stored in appropriate containers. Because of its corrosive nature in liquid form, tanks and pipes must be made of resistant materials like fiberglass or cross-linked polyethylene. The compound can be fed straight into water systems, however, or blended with organic polyelectrolytes. It is not considered a marine pollutant and, despite its properties, it is used to reduce odor and corrosion.

The many applications of this compound in the industrial sector include dyeing, coagulation for pigments or industrial wastes, potable drinking water production, municipal and industrial wastewater treatment, and sludge conditioning. It works to prevent odor by eliminating hydrogen sulfide. This compound works in a wide pH range too and decomposes at a high temperature. In other non-industrial sectors, ferric sulphate is also used to remove natural organic matter in water, such as bacteria, arsenic, and heavy metals.