Electrodissolution Kinetics of Iron in Chloride Solutions: VI . Concentrated Acidic Solutions

Abstract

Anodic iron dissolution in acidic chloride solutions (constant ionic strength of 4.5M) over a wide range of H+ and Cl− concentrations has been investigated. Anodic dissolution in low [H+]‐concentrated chloride solutions is accelerated by both Cl− and OH− with Tafel slopes of 0.075 V/decade at low polarization and accelerated by only OH− with Tafel slopes of 0.04 V/decade at high polarization. On the other hand, anodic dissolution in highly acidic‐concentrated chloride solutions is accelerated by both H+ and Cl− with Tafel slopes of 0.11 V/decade and first‐order dependence on both H+ and Cl−. For low Cl− concentrations in either dilute or concentrated acidic solutions, anodic dissolution is inhibited by Cl−. The experimental results indicate that anodic iron dissolution in acidic chloride solutions proceeds by simultaneous parallel reactions. Mechanisms which are consistent with the empirical rate expressions have been developed.