Corrosion Inhibition and Hydrogen Adsorption in the Case of Iron in a Sulfuric Aqueous Medium

Abstract

The corrosion process for two iron samples of different purities in a molar solution of sulfuric acid has been studied by means of a rotating disk electrode. This study supports the previously formulated hypothesis which assigns the hysteresis, observed when corrosion is low, to the partial coverage (Θ) of the electrode surface by adsorbed hydrogen . The decrease of the cathodic reaction rate is then accounted for by a slow diminution of the number of active sites due to this coverage. The hydrogen adsorption is favored by the presence of 2‐butyne 1,4‐diol. At potentials more anodic than the corrosion potential, the same coverage persists. The study of the Θ variation with potential, in the presence of 2‐butyne 1,4‐diol, shows that Θ, close to unity near the corrosion potential, diminishes when the anodic potential increases and tends toward zero for potentials above which hysteresis is no longer observed. All these results tend to confirm the role of as a corrosion inhibitor.