On the Estimation of Standard Adsorption Free Energy from Corrosion Inhibition Efficiencies

Abstract

The standard adsorption free energy (∆G◦ads) is often estimated by assuming that the corrosion inhibition efficiency is equivalent to fractional surface coverage. However, Lindsay et al. [Corros. Sci. 155 (2019) 182–185] demonstrated that this assumption is not necessarily valid. Therefore, a model that maps inhibition efficiency to fractional surface coverage is developed herein to provide a more reliable estimation of ∆G◦ads. The model is validated with the experimental data of Lindsay et al.; the analysis confirms their conclusion that a significant error in ∆G−◦ads estimation can be made by using the inhibition efficiency as a proxy for surface coverage.

Keywords: standard adsorption free energy, Corrosion inhibition, surface coverage, adsorption isotherm