Corrosion inhibition behavior of piperidinium based ionic liquids on Q235 steel in hydrochloric acid solution: Experimental, density functional theory and molecular dynamics study

Abstract In the present time, there is enormous need for environmentally friendly and effective corrosion inhibitors that can reduce tubular steel corrosion. The present paper explore the adsorption and corrosion inhibition behavior of three ionic liquids (ILs) namely 1-Methyl-1-propylpiperidinium Bromide (IL-1), 1-Butyl-1-methylpiperidinium Bromide (IL-2), and 1-Butyl-1-methylpiperidinium bis(trifluoromethanesulphonyl)imide (IL-3) at Q235 steel/1 M HCl interface using both the experimental and theoretical studies. Weight loss and electrochemical experiments suggests increase in inhibition efficiency values with increasing concentration, and reached to 91.3% (IL-1), 94.7% (IL-2) and 97.4% (IL-3) at only 400 mg/L concentration. However, increase in temperature decreases the inhibition efficiency. The addition of 0.5 mM potassium iodide (KI) enhances the performance of ILs. The adsorption of all three ILs at Q235 steel/electrolyte interface obeyed the Langmuir adsorption isotherm model. PDP study supports the mixed nature with pre-dominantly cathodic adsorption nature of ILs. SEM and AFM analyses supports the adsorption of ILs over the Q235 steel surface. Molecular dynamic (MD) simulations reveals flat adsorption and orientation mode of ILs molecules onto the Q235 steel surface. Quantum chemical, Fukui indices and MD results corroborate with the experimental results.