Experimental and theoretical studies of two imidazolium-based ionic liquids as inhibitors for mild steel in sulfuric acid solution

The inhibition performance and mechanism of 1-octyl-3-methylimidazolium bromide ([OMIM]Br) and 1-allyl-3-octylimidazolium bromide ([AOIM]Br) for the corrosion of mild steel in 0.5 M H2SO4 were investigated using weight loss method, electrochemical measurements, scanning electron microscope (SEM) and quantum chemical calculation. The results revealed that [OMIM]Br and [AOIM]Br acted as modest cathodic inhibitors, and due to the electron-donating effect of allyl group, [AOIM]Br showed better inhibitive performance. The adsorption of both inhibitors on steel surface obeyed El-Awady thermodynamic-kinetic model, thus the thermodynamic and kinetic parameters were calculated and discussed. Moreover, theoretical calculation was used to investigate inhibition mechanism of studied inhibitors. (C) 2015 Elsevier Ltd. All rights reserved.