Sodium persulphate, Na₂S₂O₈

The Sodium persulphate, Na₂S₂O₈, is formed in solution by the electrolysis of a concentrated aqueous solution of sodium sulphate at low temperature and high current-density. The solid persulphate can be obtained by double decomposition of ammonium persulphate and sodium carbonate either in the solid state or in concentrated solution, the crystalline salt being isolated from the solution either by addition of alcohol or by concentration at reduced pressure. When dry and protected from sunlight, it keeps almost unchanged for years.