Kinetics study of iron dissolution in highly concentrated acidic media using Hammett acidity function

This study aimed at establishing a mechanism of iron corrosion, in highly HCl concentrated medium, using Hammett acidity functions instead of conventional pH measurements. Linear relationships between the rate of Armco iron corrosion and the acidity of aqueous HCl media expressed in the form of Hammett acidity H0′, were obtained. At high ionic strength, it was shown by electrochemical analysis, that chloride ions were adsorbed at the metal surface and decreased the corrosion process of iron. A detailed mechanism of iron corrosion involving activity of protons H+ as promoter of the iron dissolution, the inhibiting effect of chloride activity, and activity of water as a kinetics variable parameter. It reveals that this competitive mechanism on the anodic sites, agrees well with experimental kinetic parameters obtained in this study.