Synergistic effect of 4-dimethylaminopyridine with sodium dodecyl sulfonate and potassium bromide on the corrosion inhibition of mild steel in HCl medium: a collective experimental and computational investigation

In this work, the synergistic inhibition performance of three readily available compounds that 4-dimethylaminopyridine (DMAP), potassium bromide (KBr), and sodium dodecyl sulfonate (SDS), which for the corrosion of mild steel in 1 M HCl solution was investigated by weight loss measurements, electrochemical measurements, surface analysis methods, and molecular simulation technique. The weight loss measurement shows that the ternary corrosion inhibitor still has excellent corrosion inhibition performance at high temperature, and the corrosion inhibition efficiency can be as high as 93%. Potentiodynamic polarization (PDP) results suggested that the mixture belongs to the mixed-type inhibitor which mainly inhibits the anodic reaction. Electrochemical impedance spectroscopy (EIS) measurements demonstrated that a self-assembled barrier film can be formed on the steel surface, which increased the polarization resistance and effectively hindered the corrosion. The efficiency of the mixture corrosion inhibitor reaches 83.6%, which is significantly higher than that of a single corrosion inhibitor. Surface analysis showed that the roughness of the substrate surface decreased due to the adsorption of DMAP-SDS-KBr mixture. The combined Monte Carlo (MC) and molecular dynamics (MD) simulations revealed the synergistic adsorption mechanism, which confirmed the experimental findings.