The Mechanism of Demineralization at Carbon Electrodes

The results of coulometric and mass‐balance analyses were used to establish the mechanism of demineralization and regeneration at chemically treated carbon paste electrodes. The chemical treatment results in the formation of weak acid groups on many carbon surfaces. The acid groups are ionized in the cathodic cycle by the electrochemical generation of hydroxyl ion. Anionic groups thus produced result in depletion of cations from solution. During regeneration, the hydrogen which was adsorbed on the carbon during the demineralization cycle is oxidized, giving rise to acid conditions. The anionic groups are thus converted back to the acid form, and cations are released to the solution.