Experimental and computational analysis of the corrosion inhibition performance of 2-[2-(hydroxy benzylidene)amino]benzoic acid Schiff base on mild steel in 1M hydrochloric acid

The corrosion inhibition efficiency of 2-[2-(hydroxybenzylidene)amino] benzoic acid Schiff base on mild steel in an acidic medium was evaluated using gravimetric analysis and potentiodynamic polarisation (PDP) techniques. Characterization via FTIR and SEM confirmed the formation of a protective inhibitor layer on the metal surface. The inhibitor’s efficiency increased with concentration, reaching 89.98% at 0.4 mM, but decreased with temperature, dropping to 51.54% at 333 K. PDP analysis classified the Schiff base as a mixed-type inhibitor, and the adsorption followed the Langmuir isotherm. A negative value of ΔGads (-34.04 kJ/mol) indicates strong and spontaneous adsorption. DFT calculations highlighted strong electron density around the C=N and hydroxyl groups, reinforcing the physisorption mechanism. Overall, experimental and computational results validated the Schiff base as an effective corrosion inhibitor for mild steel in 1 M HCl, demonstrating strong adsorption and excellent protective properties.