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OXIDATION OF MANGANOUS AND CHLORIDE IONS ON MIXED METAL OXIDE ANODES
Alex Luyima and Michael Moats*
Materials Research Center, Missouri University of Science and Technology, Rolla, MO, USA, 65409
*Corresponding author email: moatsm@mst.edu
ABSTRACT
In the present work, the oxidation of manganous (Mn2+) and chloride (Cl-) ions on a mixed metal oxide
anode (Ti/IrO2-Ta2O5).in an electrolyte containing 160 g/L H2SO4, 0-12.5 g/L Mn2+, and 0-2.5 g/L Cl- at 40 oC was
studied using cyclic voltammetry (CV). CV results indicated that Mn2+ concentration does not affect the oxidation
of Cl- ions to Cl2 gas on a non-MnO2 coated Ti/IrO2-Ta2O5 anode. However, once Mn2+ ions are oxidized to MnO2
at the anode, Cl2 evolution is inhibited.
The effects of manganous concentration, chloride concentration and a commercial electrowinning organic
additive (Cyquest® N-900) on the amount of MnO2 deposited at the anode in one hour were evaluated. The
concentration of Cl- in the electrolyte did not affect the amount of MnO2 generated. Conversely, Mn2+ concentration
affected the amount of MnO2 generated. And lastly, the presence of Cyquest N-900 inhibited MnO2 deposition at
the anode under certain experimental conditions tested, but not those experienced in zinc electrowinning.