Study of the electrodeposition conditions of metallic manganese in an electrolytic membrane reactor

This paper reports the optimization of the process parameters for the electrodeposition of manganese in an electrolytic membrane reactor. The manganese(II) and ammonium ion concentrations, pH, temperature and additives to the electrolyte were varied over a relatively broad range to evaluate the changes in the current efficiency and specific energy consumption of manganese electrodeposition. The catholyte was aqueous manganese(II) sulfate containing ammonia sulfate, and the anolyte was a sulfuric acid solution. An anionic membrane separated the anolyte from the catholyte while maintaining a conductive path between the two. A high current efficiency and low specific energy consumption were favored at a pH of 7.5 with additive incorporation. Under the optimized conditions, a maximum current efficiency of 85.86% was attained with an electrolyte composition of 35 g/L Mn and 130 g/L (NH4)2SO4 at a temperature of 40 °C and a pH of 7.5 in the presence of additives and with a cathode current density of 400 A/m2. The electrolysis experiment over time showed that the specific energy consumption was 4779 kW h/t of Mn deposited under the optimum conditions.