Influence of three N-based auxiliary additives during the electrodeposition of manganese

In the presence of the SO2-type main additive, the effect of three N-based auxiliary additives, including ammonium thiocyanate, thiourea and polyacrylamide, during the electrodeposition of manganese was investigated. We found that ammonium thiocyanate decreased the amount of S-polyanions (SO32- and HSO3-) in the system, thereby exerting negative effects on the surface that led to low current efficiency. Thiourea (BT) maintained the S-polyanion distribution on the electrode interface, and the high-valence manganese compounds were promptly reduced to Mn2+. Consequently, energy and material consumption decreased. Polyacrylamide (PAM) prevented metal sulfides from diffusing into the metallic lattice on the solid-liquid interface, resulting in white, lightweight deposited manganese. Moreover, PAM-BT mixture auxiliary additive helped save energy and materials during the electrodeposition process and improved product quality, with both processes working synergistically. The mechanism of three auxiliary additives during the electrodeposition was studied. Our results may provide a theoretical guidance for the selection of auxiliary additives during the metal electrodeposition process. (C) 2014 Elsevier B.V. All rights reserved.