The peroxydisulfate ion, , is an
oxyanion, the anion of
peroxydisulfuric acid. 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, sulfur ...
, 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-life. ...
(Na
2S
2O
8),
potassium persulfate
Potassium persulfate is the inorganic compound with the formula K2 S2O8. Also known as potassium peroxydisulfate, it is a white solid that is sparingly soluble in cold water, but dissolves better in warm water. This salt is a powerful oxidant, co ...
(K
2S
2O
8), and
ammonium persulfate
Ammonium persulfate (APS) is the inorganic compound with the formula (NH4)2S2O8. It is a colourless (white) salt that is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used as a cataly ...
((NH
4)
2S
2O
8). 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, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or at the terminal position. Terminal alkenes are also known as Alpha-olefin, α-olefins.
The Internationa ...
, including
styrene
Styrene is an organic compound with the chemical formula C6H5CH=CH2. Its structure consists of a vinyl group as substituent on benzene. Styrene is a colorless, oily liquid, although aged samples can appear yellowish. The compound evaporates easi ...
,
acrylonitrile, 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 fo ...
is
initiated 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
* Oxidation of Ag
+ to Ag
2+, such as the preparation of
tetrakis(pyridine)silver(II) peroxydisulfate
Structure
Peroxydisulfate is a centrosymmetric anion. The O-O distance is 1.48 Å. The sulfur centers are tetrahedral.
References
{{Persulfates
*
Sulfur oxyanions