Abstract
This work investigates the corrosion inhibition of carbon steel in 0.5 mol·dm⁻³ H₂SO₄ using a binary system of 1,2-phenylenediamine and disodium naphthalene-1,5-sulfonate. Experimental techniques, including weight loss assay, electrochemical methods, and surface analysis, demonstrated significant inhibition efficiency, reaching 88.43% under optimal conditions. The synergistic effect between the two components was evaluated as 2.59, indicating enhanced performance compared to individual components. Computational studies using molecular dynamics and DFT revealed strong interactions, driven by the formation of hydrogen bonding promoted by electrostatic forces during adsorption, which stabilize the protective layer on the metal surface. The adsorption mechanism was consistent with the Langmuir adsorption model, and obtained thermodynamic parameters confirmed spontaneous physisorption of the inhibitor. Electrochemical results identified the binary system as a mixed-type inhibitor, effectively reducing both anodic and cathodic corrosion processes. These findings provide valuable insights into the design of synergistic inhibitor systems for industrial applications.