Anti-corrosion performance of novel pyrazole derivative for carbon steel corrosion in 1 M HCl: Computational and experimental studies

The inhibition influence of synthesized ethyl 5-methyl-1-(((6-methyl-4-nitropyridin-3-yl)amino)methyl)-1Hpyrazole-3-carboxylate (EMPC) on corrosion of carbon steel (CS) in 1 M HCl solution was investigated using mass loss measurements, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements (PDP) techniques. The experimental results show that the inhibition efficiency of EMPC increased with the increase in inhibitor concentration but decreased with an increase in temperature, reaching a maximum of 92 % with 10(-3) M at 303 K. The PDP measurement illustrates the anodic-type behavior of EMPC. The Nyquist plots showed that polarization resistance increased and double-layer capacitance decreased on increasing the concentration of the studied inhibitor due to the adsorption of inhibitor molecules on the CS surface. The adsorption of EMPC on the surface of CS obeyed Langmuir isotherm. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD), were employed to examine corrosion products and results indicate a layer being formed on the CS by EMPC that protects the CS from further corrosion. The mechanism of the inhibition process was discussed in light of the chemical structure and quantum chemical calculations of the investigated inhibitor.