Experimental and theoretical approaches for interfacial adsorption of novel long chain benzimidazolium derivatives for mild steel protection in 1 M HCl medium

In this work, we are interested in the study of the anti-corrosion effect of new organic compounds of the typebenzimidazolium derivativesnominated 1,3-Dinonyl-2-(nonylthio)-1H-benzimidazolium bromide (ImdC7B), 1,3-Didecyl-2-(decylthio)-1H-benzimidazolium bromide (ImdC8B) and 1,3-Didodecyl-2-(dodecylthio)-1H-benzimidazolium bromide (ImdC9B)on the corrosion of mild steel (MS) in 1 M hydrochloric acid and 1 M HCl media exploiting electrochemical techniques [polarization curves (PC) and impedance spectroscopy (IS)]. In addition to that a correlation between molecular structures and inhibitory activity was carried out exploiting the DFT (Density Functional Theory) method and molecular dynamics (MD) simulation. The results obtained show an increase in efficiency with concentration. A maximum of 94.7%, 95.7% and 96.9% is reached for a concentration of 10-3 M of ImdC7B, ImdC8B and ImdC9B respectively. Polarization curves studies have demonstrated that these compounds are some mixed inhibitors. The ImdC7B, ImdC8B and ImdC9Bare adsorbed on the surface of MS according to Langmuir model. Reactivity parameters predicted from density functional theory calculations suggested the involvement of protonated forms of the molecules in the inhibitive process, which is also supported by the adsorption characteristics derived from MD simulations.