Abstract
The corrosion inhibition properties of two inhibitors, 2-Amino-4-(4-chlorophenyl)-3-cyano-7,7-dimethyl-5-oxo-4H-5,6,7-tetrahydrobenzo[b] pyran (ZE1-4-Cl) and 2-Amino-3-cyano-4-(4-nitrophenyl)-7,7-dimethyl-5-oxo-4H-5,6,7,8-tetrahydrobenzo[b] pyran (ZE2-4- NO2), on mild steel in a 1.0 M HCl solution was evaluated using Tafel polarization and Electrochemical Impedance Spectroscopy (EIS). The inhibitory efficiency increases with decreasing temperature. Additionally, the inhibitory efficiency also increases with increasing inhibitor concentration. Notably, the better inhibitor of the two (ZE2-4- NO2) achieves an efficiency of 93.7% at a temperature of 298 K and an optimal concentration of 10− 3M. The adsorption of both inhibitors on the steel surface was found to follow the Langmuir model, and the polarization study shows that both compounds are adsorbed to the metal surface through chemical bonding (chemisorption) following the Langmuir isotherm. The experimental results reveal that these organic compounds are effective corrosion inhibitors in a 1.0 M HCl solution. SEM and Energy Dispersive X-Ray Analysis (EDS) were employed to confirm the presence of a barrier layer enveloping the mild steel, contributing to surface characterization. Notably, interactions with the iron surface are primarily facilitated by inhibitors possessing electron-accepting properties, as evidenced by DFT results and molecular dynamic (MD) simulations.