The effects of aging time on the corrosion inhibition performance of KI and its synergistic effect with a typical phosphorus-based ionic liquid inhibitor

Potassium iodide (KI) is regarded as an ideal synergist for typical corrosion inhibitors . However, the synergistic effect of KI may be compromised due to its oxidation in acidic solutions. In this work, the anticorrosion performance of KI with different aging times in HCl solution and their synergistic effect with dodecyltriphenylphosphonium bromide (C 12 TPB) were evaluated via electrochemical tests and surface characterization techniques. The corrosion inhibition efficiency of KI gradually increased from 6.41 % to 38.99 % with increasing aging time to 6 h, while the synergy coefficient between KI and C 12 TPB abnormally decreased from greater than 1.0 to less than 0.4. UV–vis results and quantum chemical calculation demonstrated that the generated I 3 − during the aging process caused negative impact on the adsorption of C 12 TPB, leading to the reduced anticorrosion performance. This study provides valuable insights for the rational utilization of KI as the corrosion inhibitor and synergist.