Investigation of the mechanisms and adsorption of a new pyrazole derivative against corrosion of carbon steel in hydrochloric acid solution: Experimental methods and theoretical calculations

In an electrolyte of hydrochloric acid (1 M HCl) at 303 K, the effectiveness of the pyrazole derivative N,N,N′,N′-tetrakis((3,5-dimethyl-1 H-pyrazol-1-yl)methyl)pyridine-2,6-diamine (PRPD) as a corrosion inhibitor was examined. Several experimental methods, such as electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface morphology analysis (SEM) coupled with energy dispersive X-ray analysis (EDX), AFM, contact angle (CA), FTIR, X-ray photoelectron spectroscopy (XPS), UV–visible, and X-ray diffraction (XRD), were used to conduct the measurements. To support these experimental findings, we use theoretical calculations such as density functional theory (DFT) and molecular dynamics (MD) simulations. The achieved findings manifested that the PRPD behaves as a powerful corrosion inhibitor, achieving an anti-corrosion performance of 97.2% at 0.001 M. The PDP technique suggests that PRPD is part of a mixed-type inhibitor. The PRPD molecules are chemisorbed at the carbon steel (CS) surface in accordance with the Langmuir isotherm model. On the ground of surface analysis, the build-up of an adsorptive layer inhibitor on the steel surface has been verified. DFT and MD simulation analyses have validated the experimental findings. These results contribute to the creation of successful corrosion control methods by providing insightful information about the inhibition of carbon steel corrosion in a 1 M HCl environment.