Experimental and computational studies of imidazolium based ionic liquid 1-methyl-3-propylimidazolium iodide on mild steel corrosion in acidic solution

Abstract

Corrosion inhibitive property of ionic liquid 1-Methyl-3-propylimidazolium iodide (MPII) on Mild Steel in 1 M H2SO4 was investigated by experimental and computational Studies. The inhibition efficiency of inhibitor MPII at various concentrations, temperature and time duration were studied by gravimetric measurements, potentiodynamic polarization techniques, electrochemical impedance spectroscopy (EIS), surface studies and computational studies. The results from potentiodynamic polarization studies revealed that inhibitor 1-Methyl- 3-propylimidazolium iodide acts as a mixed type inhibitor with a high inhibition efficiency of 91% at 298 K. Adsorption of the inhibitor on the surface of mild steel follows the Langmuir adsorption isotherm. The mechanism of adsorption was also validated by quantum chemical studies. Morphology and topography of the Mild Steel surface with and without the inhibitor were investigated by SEM. Thermodynamic parameters for adsorption like adsorption equilibrium (K-ads), Delta H-ads, Delta S-ads, Free energy of adsorption i.e. Delta G(ads) were also calculated so as to project the mechanism of adsorption. Computational data obtained from the Density functional theory (DFT) were used to acquire detailed theoretical insights. Appreciably Electrochemical impedance spectroscopy, Molecular dynamic simulation and quantum chemical calculation confirms the interaction of inhibitor with metal which leads to increases in inhibition efficiency.