Electrodeposition of Iron in HNO3 Solution Containing Iron Dissolved from Copper Slag

Abstract

Electrochemical deposition of iron in HNO3 solution containing iron dissolved from copper slag was investigated with varying pH and chemical components of the solution in this study. The pH dependency of reduction potentials of ionized iron and copper species facilitated the elimination of copper inclusion in electrodeposited iron-based layers. Hydrogen evolution in competition with iron reduction from preferentially ferric ions was also diminished by increasing pH of the solution with NaOH addition. Adding malonic acid was effective to considerably diminish the oxidation of reduced iron due to the complexation between ferric ion and malonate (Mal) ligand. However, iron oxidation could not be completely inhibited by adding malonic acid because a partial transition of Fe(Mal)+ ions to ferrous ions, which can react readily with oxygen during electrodeposition, would occur at low cathodic potentials. Controlling malonic acid concentration could lead to the formation of α-Fe with very low oxygen content less than 0.15 wt%.