Method for producing peroxodisulfates in aqueous solution

Abstract

The invention describes a method for producing or regenerating persulfuric acid and the salts thereof by electrolysis of an aqueous solution containing sulfuric acid and / or metal sulfates on diamond-coated electrodes without using promoters. According to the inventive method, bipolar silicon electrodes are used which are diamond-coated on one side and whose uncoated silicon back is used as the cathode.

Description

technical field

[0001] The present invention relates to a process for the preparation or regeneration of peroxodisulfuric acid and its salts by electrolysis of aqueous solutions comprising sulfuric acid and / or metal sulfates. As used herein, the term "metal sulfate" includes sulfates of alkali metals and alkaline earth metals or ammonium sulfate in addition to sulfates of metals such as zinc, nickel or iron. For example, alkali metal sulfates or alkaline earth metal sulfates, preferably alkali metal sulfates or ammonium sulfate, can be used as metal sulfates. It is also possible to use various metal sulfates, for example mixtures of magnesium sulfate, zinc sulfate or nickel sulfate or iron sulfate, preferably in the regeneration of etching and pickling solutions. Background technique

[0002] It is known from the prior art that diamond-coated electrodes consisting of a valve metal, preferably niobium, or of a ceramic material, preferably silicon, can be used for the prepara...