Corrosion inhibition effect of 5-(4-methylpiperazine)-methylquinoline-8-ol on carbon steel in molar acid medium

The present study provides a new application of the 5-(4-methylpiperazinyl)-methylquinolin-8-ol (MPMQ) as an inhibitor for corrosion of carbon steel (CS) in acidic media (1 M HCl). The inhibition performance of MPMQ was evaluated using various methods including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), surface morphology analysis (SEM), quantum chemical computations (DFT), and Monte Carlo simulations (MC). The obtained results, indicating that the compound as a mixed-type inhibitor significantly reduced the corrosion rate of CS due to the formation of a stable protective film on the metal surface. As confirmed by EIS, SEM and theoretical studies, chemically adsorbed MPMQ molecule is a better corrosion inhibitor with higher corrosion performance of about 95% at room temperature. Langmuir isotherm model is the most acceptable one to describe the MPMQ molecules adsorption on the CS-surface. Finally, the experimental data correlated well with the theoretical study.

Automated summary

This study demonstrates the application of MPMQ as a corrosion inhibitor for carbon steel in acidic media with significant reduction in corrosion rate due to the formation of a protective film. The chemically adsorbed MPMQ molecule exhibited superior corrosion inhibition performance of about 95% at room temperature. The Langmuir isotherm model was found to be the most suitable for describing MPMQ molecules adsorption on the CS surface, with good correlation between experimental data and theoretical study.