Imidazolium based ionic liquid derivatives; synthesis and evaluation of inhibitory effect on mild steel corrosion in hydrochloric acid solution

Imidazolium bearing ionic liquids (ILs), 3-hexadecyl-1-methyl-1H-imidazol-3-ium bromide [C(16)M(1)Im] [Br] and 3-hexadecyl-1,2-dimethyl-1H-imidazol-3-ium bromide [C(16)M(2)Im] [Br] have been synthesized. These compounds were evaluated for corrosion resistance of mild steel in 1M HCl solution by gravimetric and electrochemical studies. The results were noticed that the inhibition efficiency, has enhanced due to a rise in the concentration of inhibitor. Further, it is observed that [C(16)M(2)Im] [Br] inhibition efficiency better than [C(16)M(1)Im] [Br] due to the increased alkyl substituents. Polarization study reveals that the used inhibitors behave as a mixed type, but predominantly exhibited the anodic inhibitive effect. The inhibitors adsorbed on the metal surface obeys Langmuir adsorption isotherm. Surface topography examined using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM) with EDAX analyses. The formation of the Fe-inhibitor complex on mild steel surface has been confirmed by UV-Visible spectroscopy.