Electrochemical study of the corrosion behaviour of iron in presence of new inhibitor in 1 M HCl

In this work, the effect of a synthesised organic molecule containing heteroatoms such as nitrogen and sulphur on the corrosion behaviour of iron was investigated. Electrochemical studies of the iron samples were performed in an aerated solution of 1 M HCl by means of electrochemical impedance spectroscopy as well as polarisation curves. The recorded electrochemical data showed that the corrosion resistance was greatly enhanced in presence of inhibitor; it acts at the same time on the anodic and cathodic electrochemical processes and its effect depends on its concentration. These results were confirmed by the impedance tests where it was observed that the effect of inhibitor addition appears by an increase in the resistance and especially by a strong reduction of the capacity of interface. Study of the temperature effect showed that the compound tested is adsorbed according to the model of Temkin. The maximal protection efficiency exceeded 94%. Theoretical calculations indicate that the protonation is easier on the site of the amine group. The corrosion protection could be explained by the adsorption of inhibitor through the N-atom and formation of a protective layer attached to the metal surface. (C) 2003 Published by Elsevier B.V.