Inhibition properties of 4,5-dihydroxy-4,5-di-p-tolylimidazolidine-2-thione for use on carbon steel in an aggressive alkaline medium with chloride ions: Thermodynamic, electrochemical, surface and theoretical analyses

Abstract

The inhibition properties of 4,5-dihydroxy-4,5-di-p-tolylimidazolidine-2-thione (DHDTIT) for use on carbon steel in a 1 M NaOH +1 M NaCl medium was fully characterised and investigated by thermodynamic, electrochemical, surface and theoretical analyses. The obtained results are as follows. The inhibition efficiency of DHDTIT for carbon steel is over 95–96% at the optimum concentration in this medium. DHDTIT demonstrates mixed-type behaviour. The negative values of ∆Gadso and ∆Hadso show that the inhibition process occurs spontaneously and that the physical and chemical adsorption on the metal surface is endothermic. The Cdl and solution conductivity are very low in the inhibited medium. DFT calculations confirm the experimental results and indicate that the molecular structure is a significant factor of the inhibition characteristics. Finally, molecular dynamics (MD) simulations confirm the successful interfacial adsorption of this inhibitor on the Fe (110) surface.