Peroxydisulfate

The peroxydisulfate ion, S
₂O²⁻
₈, is an oxyanion, the anion of peroxydisulfuric acid. It is commonly referred to as persulfate, but this term also refers to the peroxomonosulfate ion, SO²⁻
₅. It is also called peroxodisulfate.^[2] Approximately 500,000 tons of salts containing this anion are produced annually. Important salts include sodium persulfate (Na₂S₂O₈), potassium persulfate (K₂S₂O₈), and ammonium persulfate ((NH₄)₂S₂O₈). These salts are colourless, water-soluble solids that are strong oxidants.^[3]

Peroxydisulfate

Names
Other names Peroxodisulfate Persulfate[1]
Identifiers
CAS Number	15092-81-6
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29267
ChemSpider	97014
PubChem CID	107879
UNII	1SQ1481FEQ
InChI InChI=1S/H2O8S2/c1-9(2,3)7-8-10(4,5)6/h(H,1,2,3)(H,4,5,6)/p-2 Key: JRKICGRDRMAZLK-UHFFFAOYSA-L
SMILES [O-]S(=O)(=O)OOS([O-])(=O)=O
Properties
Chemical formula	O8S2−2
Molar mass	192.11 g·mol−1
Conjugate acid	Peroxydisulfuric acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Applications

Salts of peroxydisulfate are mainly used to initiate the polymerization of various alkenes, including styrene, acrylonitrile, and fluoroalkenes. Polymerization is initiated by the homolysis of the peroxydisulfate:

[O₃SO–OSO₃]²⁻ ⇌ 2 [SO₄]^•−

Moreover, sodium peroxydisulfate can be used for soil and groundwater remediation, water and wastewater treatment, and etching of copper on circuit boards.^[4][2]

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.^[2]

In addition to its major commercial applications, peroxydisulfate participates in reactions of interest in the laboratory:

• Elbs persulfate oxidation
• Oxidation of Ag⁺ to Ag²⁺, 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.^[5]

References

1. Ambiguous—see persulfate
2. Shafiee, Saiful Arifin; Aarons, Jolyon; Hamzah, Hairul Hisham (2018). "Electroreduction of Peroxodisulfate: A Review of a Complicated Reaction". Journal of the Electrochemical Society. 165 (13): H785–H798. doi:10.1149/2.1161811jes. S2CID 106396614.
3. Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort. "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3527306732.{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link)
4. Wacławek, Stanisław; Lutze, Holger V.; Grübel, Klaudiusz; Padil, Vinod V.T.; Černík, Miroslav; Dionysiou, Dionysios.D. (2017). "Chemistry of persulfates in water and wastewater treatment: A review". Chemical Engineering Journal. 330: 44–62. doi:10.1016/j.cej.2017.07.132.
5. Allan, David R. (2006). "Sodium Peroxodisulfate". Acta Crystallographica Section E. 62 (3): i44–i46. doi:10.1107/S1600536806004302.