The salt is prepared by the electrolytic oxidation of sodium bisulfate:
Oxidation is conducted at a platinum anode.[2] In this way about 165,000 tons were produced in 2005.[3]
The standard redox potential of sodium persulfate into hydrogen sulfate is 2.1 V, which is higher than that of hydrogen peroxide (1.8 V) but lower than ozone (2.2 V).[4] The sulfate radical formed in situ has a standard electrode potential of 2.7 V.
However, there are a few drawbacks in utilizing platinum anodes to produce the salts; the manufacturing process is inefficient due to oxygen evolution and the product could contain contaminants coming from platinum corrosion (mainly due to extremely oxidizing nature of the sulfate radical). Thus, boron-doped diamond electrodes have been proposed as alternatives to the conventional platinum electrodes.[5]
Structure
The sodium and potassium salts adopt very similar structures in the solid state, according to X-ray crystallography. In the sodium salt, the O-O distance is 1.476Å. The sulfate groups are tetrahedral, with three short S-O distances near 1.44 and one long S-O bond at 1.64Å.[1]
^Block, Philip A., Richard A. Brown, and David Robinson. "Novel activation technologies for sodium persulfate in-situ chemical oxidation." Proceedings of the Fourth International Conference on the remediation of chlorinated and recalcitrant compounds. 2004.
^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.
^Luchtefeld, Ron; Dasari, Mina S.; Richards, Kristy M.; Alt, Mikaela L.; Crawford, Clark F. P.; Schleiden, Amanda; Ingram, Jai; Hamidou, Abdel Aziz Amadou; et al. (2008). "Synthesis of Diapocynin". J. Chem. Educ.85 (3): 411. Bibcode:2008JChEd..85..411D. doi:10.1021/ed085p411.