Theory of Electrochemical Oxidation

A saturated solution of sodium tetraborate, also containing both carbonate and bicarbonate of sodium, is used as the eleotrolyte. The presenoe of excessive solid borax guarantees that the solution is continuously resaturated with this compound during electrolysis. The eleotrolyte is also saturated with perborate so that this salt, which is formed by anodic oxidation of borax, is separated from the solution immediately after its formation in the form of small crystals. 

Carbonate is neoessary for electrolysis, as otherwise perborate could not be formed. For this reason its formation is supposed to take place in such a way that sodium per carbonate is first formed at the anode  

The hydrogen peroxide then combines with the metaborate ion BO to form the complex ion  

As hydrogen is liberated at the cathode the overall process during electrolysis is expressed by this equation  

The electrochemical oxidation of sodium tetraborate to perborate is accompanied with a corresponding decrease in alkalinity of the electrolyte i. e. the quantity of carbonate decreases and that of bicarbonate increases during the alectrolysis according to the equation  

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