Electrolytic manganese dioxide from chloride electrolyte: Anode potential measurements

In the preparation of electrolytic manganese dioxide (EMD) the dependence of anode potentials on conditions of electrolysis,viz.,temperature, anodic current density and concentration of hydrochloric acid, has been studied and the behaviour of uncoated and MnO2, coated graphite in HCl, H2SO4 and MnCl2-HCl electrolyte has been compared. It is observed that above 70 degrees C, below an anode current density of 100 Am-2 and below a concentration of 20 g/L hydrochloric acid, the deposition of manganese dioxide takes place preferentially. Among the probable electrochemical reactions EMD deposition, oxygen evolution and chlorine evolution occur under the present experimental conditions. The data collected employing an all-glass apparatus also confirm the results.