Molecular Simulation of Corrosion Inhibition Mechanism of Azole Corrosion Inhibitor in Halogen-Containing Acidic Solution

Molecular simulation method was used to study the film formation mechanism of azole inhibitors with different head groups, including 2-mercaptobenzoxazole (MBO), 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT), on Fe surface in halogen-containing sulfuric acid solution. The corrosion inhibition mechanism of different azole inhibitors was systematically explored in terms of equilibrium adsorption configuration, distribution and migration of water molecules in the inhibitor film, and interaction energy between the inhibitor and metal surface. The results show that the order of inhibition efficiency of three inhibitors was MBT>MBI>MBO. The electrostatic interaction between protonated inhibitor head group and negatively charged metal surface halogen ions was the key to the difference of film-forming performance of different azole inhibitors. The synergistic effect of halogen ions and protonated inhibitor molecules could greatly enhance the corrosion inhibition ability of inhibitors in acidic solutions.