The peroxydisulfate ion, , is an

oxyanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...

, the anion of

peroxydisulfuric acid Peroxydisulfuric acid is an inorganic compound with a chemical formula . Also called Marshall's acid after Professor Hugh Marshall, who discovered it in 1891. Structure and bonding This oxoacid features sulfur in its +6 oxidation state and a ...

. It is commonly referred to as

persulfate A persulfate (sometimes known as peroxysulfate or peroxodisulfate) is a compound containing the anions or . The anion contains one peroxide group per sulfur center, whereas in , the peroxide group bridges the sulfur atoms. In both cases, sulfu ...

, but this term also refers to the peroxomonosulfate ion, . It is also called ''peroxodisulfate''. Approximately 500,000 tons of salts containing this anion are produced annually. Important salts include

sodium persulfate Sodium persulfate is the inorganic compound with the formula Na2 S2 O8. It is the sodium salt of peroxydisulfuric acid, H2S2O8, an oxidizing agent. It is a white solid that dissolves in water. It is almost non-hygroscopic and has good shelf-lif ...

(Na₂S₂O₈), potassium persulfate (K₂S₂O₈), and ammonium persulfate ((NH₄)₂S₂O₈). These salts are colourless, water-soluble solids that are strong oxidants.:

Applications

Salts of peroxydisulfate are mainly used to initiate the polymerization of various

alkenes In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond. Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, a ...

, including

styrene Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...

acrylonitrile Acrylonitrile is an organic compound with the formula and the structure . It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. In terms of its molecula ...

, and fluoroalkenes.

Polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many f ...

initiated Initiation is a rite of passage marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components. In an extended sense, it can also signify a transformation ...

by the homolysis of the peroxydisulfate: : ₃SO–OSO₃sup>2− 2 O₄sup>•− Moreover, sodium peroxydisulfate can be used for soil and

groundwater remediation Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the sub ...

, water and wastewater treatment, and etching of copper on circuit boards. It has also been used to produce hair lighteners and bleaches, medical drugs, cellophane, rubber, soaps, detergents, adhesive papers, dyes for textiles, and in photography. In addition to its major commercial applications, peroxydisulfate participates in reactions of interest in the laboratory: *

Elbs persulfate oxidation The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form ''para''-diphenols. The reaction is generally performed in water at room temperatures or below, using equimolar quantities of reagents. ...

* Oxidation of Ag⁺ to Ag²⁺, such as the preparation of tetrakis(pyridine)silver(II) peroxydisulfate

Structure

References

* Sulfur oxyanions {{Inorganic-compound-stub