Insight into the corrosion inhibition performance of two quinoline-3-carboxylate derivatives as highly efficient inhibitors for mild steel in acidic medium: Experimental and theoretical evaluations

Abstract

In this project, the protective effect of two newly quinoline-3-carboxylate derivatives methyl 2-amino-4-(4-chlorophenyl)-4H-pyrano[3,2–h]quinoline-3-carboxylate (P-1) and methyl 2-amino-4-(4-methoxyphenyl)-4H-pyrano[3,2–h]quinoline-3-carboxylate (P-2) on mild steel (MS) in 1 M HCl has been assessed through using electrochemical techniques, scanning electron microscope (SEM and Energy Dispersive X-ray (EDX), Uv–visible spectroscopy, as well as theoretical calculations. The experimental outcomes exhibited that P-1 and P-2 have largely inhibited the MS corrosion and their inhibition efficiency enhances with the increase of concentration. The maximum inhibition efficiency of P-1 and P-2 was figured out to be 89.8 and 94.1% at 1 mM, respectively. Potentiodynamic polarization (PDP) studies exhibited that P-1 and P-2 behave as cathodic-type inhibitors. The results of EIS suggest the increase in Rp values with increasing amount with maximum value of 558 Ω cm2 for P-2 and 330 Ω cm2 for P-1. Adsorption of P-1 and P-2 on MS surface is examined by SEM-EDX, Uv–visible, and different isotherm models, which obeys Langmuir isotherm. Furthermore, Density functional theory (DFT) and molecular dynamics simulation (MDS) calculations were implemented to understand the corrosion resistance mechanism.