Influence of N2, N6-bis((3,5-dimethyl-1h-pyrazol-1-yl)methyl) pyridine-2,6-diamine on C35E steel corrosion in 1 M HCl medium: Experimental and theoretical studies

The inhibition effect of N2, N6-bis((3,5-dimethyl-1H-pyrazol-1-yl)methyl)pyridine-2,6-diamine (MH-PA) on the corrosion of C35E steel in 1 M HCl solution was investigated employing potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier-transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), contact angle, X-ray photoelectron spectroscopy (XPS) methods, UV-visible spectroscopy, and theoretical calculation methods. The inhibition efficiency increased with increasing MH-PA concentration and decreased with increasing temperature, attaining 98% inhibition efficiency at 10−3M under 303K. PDP studies indicated that MH-PA is a mixed-type corrosion inhibitor and its adsorption mode conforms to Langmuir isotherm. UV-visible and FTIR spectroscopy support MH-PA adsorption over the C35E steel surface. The surface analysis through SEM, EDS, AFM, and contact angle corroborates the formation of the protective layer of MH-PA molecules on the C35E steel surface. In addition, XPS analysis revealed the formation of an N-Fe bond. Thermodynamic properties revealed that MH-PA has both physical and chemical adsorption behavior. Molecular dynamics simulations manifest that MH-PA molecules adsorb parallel to the Fe (110) surface.