Imidazolium based ionic liquid as an efficient and green corrosion constraint for mild steel at acidic pH levels

Abstract

Anticorrosion impact of a green ionic liquid 3-(4-fluorobenzyl)-1-methyl-1H-imidazol-3-ium bromide [FBMIm]Br has been studied for mild steel in 0.5 M H2SO4 solution using computational and electrochemical methods. The structure of the obtained [FBMIm]Br was confirmed by using 1H NMR, 13C NMR, and FTIR spectroscopy, which also confirm the absence of any major impurity. The adsorption of this ionic liquid on the mild steel surface nicely follows Langmuir adsorption isotherm. The corrosion data extracted from Tafel plots and electrochemical impedance spectroscopy (EIS) indicate quite high inhibition effectiveness at acidic pH levels providing 98.90% and 99.48% efficiency using polarization and EIS methods respectively with 0.01 M IL at 298 K. Polarization curves also suggest that the molecule shows mixed mode of inhibition. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) observations of mild steel surface confirmed the existence of protective inhibitor film on metal surface in the presence of this ionic liquid. The computational descriptors given by density functional theory (DFT) and advanced molecular dynamics (MD) simulation of the present molecule have also supported the experimental findings within the satisfactory limits and strengthened the overall study.