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

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.