Electrochemical and quantum chemical assessment of linoleic acid as a corrosion inhibitor for carbon steel in sulfuric acid solution

Abstract The corrosion inhibition performance of linoleic acid (LA) for 1018 carbon steel in 0.5 M H2SO4 solution was evaluated by using potentiodynamic polarization curves, electrochemical impedance spectroscopy and weight loss measurements. These tests were complemented by theoretical calculations using density functional theory (DFT). The inhibition efficiency increased with increasing the LA concentration but it decreased with an increase in the temperature. LA was found to be a mixed type inhibitor which is physically adsorbed on to carbon steel by following the Langmuir adsorption isotherm. Theoretical studies suggest that LA is a more effective inhibitor in acidic media than in neutral environments. Thus, in acidic media LA had the highest EHOMO value, the best chemical reactivity, the greatest tendency to transfer electrons and a greater facility of modifying its electronic configuration in presence of carbon steel specimens according to its chemical hardness value. Finally, the Tomasi Polarized Continuum Model to explain the LA adsorption on to the metal is provided.