The anodic dissolution process on active iron in alkaline solutions

Steady state anodic polarization curves were taken for Armco iron and in some experiments for high purity Puratronic iron in KOH solutions in the concentration range 5 x 10−2-5M. After the 30 min cathodic pretreatment, well reproducible anodic Tafel plots are obtained. The experimentally obtained diagnostic criteria ba = 67–70 mV dec−1, nOH− = 1.1 and nHFeO2−= −0.45 are interpreted by the anodic reaction mechanism in which FeOHadsand Fe(OH)2,ads appear as the intermediates adsorbed under Temkin conditions, the primary stable product of the electrode reaction being HFeO2−, and the final product Fe (OH)2, formed by precipitation.