Effect of hydrogen sulfide on the iron dissolution rate in a sodium sulfate solution under natural aeration conditions

The influence of hydrogen sulfide ( 10-100 mg/l) on the Armco iron anodic d issolution in an aerated 0.17 M Na2SO4 solution is investigated. During a p otentiostatic anodic polarization, the hydrogen sulfide introduction makes the current increase stepwise. The magnitude of the increase depends on the duration of preliminary anodic polarization, electrode potential, and hydr ogen sulfide concentration. The anodic metal dissolution activation by hydr ogen sulfide is explained by chemical conversion of the oxide-hydroxide pas sivating film into iron sulfide that is generated at the metal surface in t he form of a porous film and does not hinder the electrode dissolution.