Experimental and theoretical studies of five imidazolium-based ionic liquids as corrosion inhibitors for mild steel in H₂S and HCl solutions

In this study, the mild steel corrosion inhibition performance and the corresponding mechanisms of five imidazolium-based ionic liquids (ILs) in hydrogen sulfide (H₂S) and hydrochloric acid (HCl) solutions were investigated using electrochemical experiments, weight loss measurement, morphology analysis, and quantum chemical calculation. The results revealed that these ILs inhibited the corrosion of mild steel in H₂S and HCl solutions and did not change the corresponding mechanism of the corrosion reaction. The corrosion inhibition ability of these ILs decreased when the temperature increased. 1-Allyl-3-methylimidazolium bromide ([Amim]Br) exhibited the strongest mild steel corrosion inhibition capacity in H₂S and HCl solutions. The corrosion inhibition capacity of the ILs can be attributed to their adsorption on metal surfaces, which obeys the Langmuir adsorption isotherm. E _HOMO exhibited a higher influence than E _LUMO on the corrosion inhibition performance of the imidazolium-based ILs.