Investigation of a Synergistic Corrosion Inhibitor for Mild Steel in Acidic Solutions: Theoretical and Experimental Analysis

In this work, we report the synthesis, characterization and corrosion inhibition properties of the new pyrazole derivative (BM-04) on mild steel in 1.0 M HCl. Weight loss, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and SEM/EDS analysis were used to give an assessment of its protective properties. The complementary theoretical studies were performed to explain the adsorption mechanism as well as electronic property of the surface. The maximum Inhibition efficiency of BM-04 was 95.74% at a concentration level of 10⁻³ M following Langmuir monolayer adsorption. The DFT and MD calculations show that the neutral forms strongly interact with Fe(110) by donating electrons from N/O sites. MC simulations reveal competitive WSC from H₃O⁺, Cl⁻ and H₂O and the stable parallel adsorption. These results indicate that BM-04 is a potent corrosion inhibitor with thermal stability, which is promising to be applicable in acidic industrial environments. Moreover, in silico toxicological predictions offer a general safety profile for BM-04, characterized by low ecotoxicity and no major risks, reinforcing its potential as a high-performing synthetic inhibitor.