Corrosion Inhibition of E24 Carbon Steel in Sulfuric Acid by PMDA: Experimental and Theoretical Insights

The corrosion inhibition performance of a novel molecule, polymethylene dianiline (PMDA), on E24 carbon steel was investigated in sulfuric acid medium (0.5M H2SO4) using different experimental techniques. Weight loss and electrochemical measurements both demonstrated that PMDA significantly reduced corrosion rates, with inhibition efficiency increasing as the inhibitor concentration rose. Meanwhile, the protection efficiency was found to decrease at higher temperatures. Potentiodynamic polarization studies indicated that PMDA functioned as mixed type inhibitor, affecting both anodic and cathodic reactions. The adsorption pattern of PMDA on E24 carbon steel was consistent with the Langmuir isotherm model, suggesting monolayer adsorption. Surface analysis via scanning electron microscope (SEM) coupled with elemental analysis, conducted in the absence and presence of the optimal PMDA concentration, revealed the creation of a protective layer on the E24 metal in the sulfuric acid environment. Additionally, these experimental results were further validated by computational chemistry methods, including density functional theory (DFT), Monte Carlo (MC), and molecular dynamics (MD) simulations.