Synthesis and characterization of N-(2-aminophenyl)- 2-(5-methyl-1H-pyrazol-3-yl) acetamide (AMPA) and its use as a corrosion inhibitor for C38 steel in 1 M HCl. Experimental and theoretical study

Abstract

A new synthesized organic compound namely N-(2-aminophenyl)-2-(5-methyl-1H-pyrazol-3-yl) acetamide (AMPA), its structure was identified based on spectral data 1H NMR and 13C NMR, its inhibiting effect against the corrosion of C38 steel in a 1 M HCl solution has been studied by experimental and theoretical studies. The experimental studies are performed using electrochemical tests, while the theoretical studies are performed using density functional theory (DFT) calculations and Monte Carlo simulations. The results obtained show that AMPA is an effective inhibitor against the corrosion of C38 steel in an acid medium, and that its performance efficiency reaches 93% for a concentration of 5 mM. The polarization curves show that AMPA functions as a mixed inhibitor; its adsorption on the C38 steel surface undergoes the Langmuir isotherm. The electrochemical impedance spectra indicate that the value of the charge transfer resistance increases with increasing inhibitor concentrations and with increasing immersion time. The surface morphology of C38 steel in the absence and in the presence the inhibitor was analyzed by scanning electron microscopy (SEM) combined with EDX analysis. Computer calculations of synthetic corrosion inhibitor are employed to study the role of their molecular skeleton of AMPA in the corrosion inhibition process. The calculated results support the empirical results.