Adsorption behavior of 8,9-bis(4 (dimethyl amino)phenyl)benzo[4,5]imidazo[1,2-a]pyridine-6,7-dicarbonitrile on mild steel surface in 1Â M HCl

The effect of 8,9-bis(4 (dimethylamino)phenyl)benzo[4,5]imidazo[1,2-a]pyridine-6,7-dicarbonitrile (INH) on mild steel corrosion in 1 M HCl was studied by electrochemical, surface and quantum chemical calculation methods. Results showed that percentage of inhibition efficiency increases on increasing INH concentration. The maximum inhibition efficiency of 96.32% was obtained at 25 mg L−1 concentration. Tafel polarization measurements show that the presence of INH in acid solution affects both cathodic and anodic reactions but acts as predominantly cathodic type inhibitor. The Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) studies suggest the formation of adherent layer of INH on mild steel surface. The results of theoretical calculations were found to be consistent with the surface and electrochemical results.