Pyrrole-based efficient corrosion inhibitors for N80 steel: A synergistic study of experimental performance and molecular modeling

During the acidizing process of petroleum oil wells aimed at increasing oil production, a 15% HCl solution is introduced into the oil well via N80 steel (NS) tubing. This study examines the effectiveness of two pyrrole-derived compounds, N²,N⁴-bis(4-(4-methoxyphenyl)thiazol-2-yl)-3,5-dimethyl-1H-pyrrole-2,4-dicarboxamide (MPTP) and N²,N⁴-bis(4-(4-chlorophenyl)thiazol-2-yl)-3,5-dimethyl-1H-pyrrole-2,4-dicarboxamide (CPTP), in inhibiting corrosion on NS in a 15% HCl solution through methods such as weight loss, electrochemical analysis, surface examination, contact angle measurement and computational methods. The investigated pyrrole derivatives (MPTP and CPTP) were synthesized using green chemistry principles, minimizing the use of harmful solvents and reagents. Both inhibitors offer higher inhibition efficiency as compared to most of the similar type of inhibitors reported in literature. MPTP and CPTP offered maximum inhibition efficiencies of 98.1% and 96.4 %, respectively, at 303 K with a dosage of 250 ppm, while retaining significant performance at 333 K (83.02% and 74.3%, respectively). Both MPTP and CPTP demonstrated mixed inhibitory behavior, exhibiting both anodic and cathodic characteristics, and adsorbed onto NS through a mixed adsorption process that follows the Langmuir isotherm. The analyses conducted using FESEM, AFM, and XPS indicated the presence of a protective film formed by the inhibitors, which is responsible for the corrosion inhibition observed on the NS surface. Molecular modeling (DFT, Fukui and Monte Carlo simulation) studies supported the experimental results. Thus investigated inhibitors may find application in petroleum production industry.