Empirical and Theoretical Calculations for Corrosion Inhibition of Carbon Steel C1018 in Acidic Solutions Using Some Selected Fatty Acid Surfactants

Abstract

Abstract Three different surfactants based on fatty acids (octanoic, tridecanoic and oleic) and ethylenediamine were synthesized and their chemical structures were confirmed by FT-IR, 1H-NMR and 13C-NMR spectroscopy. The surface-active properties of the prepared surfactants were determined by using interfacial tension.The synthesized surfactants were evaluated as corrosion inhibitors for carbon steel in a solution of 0.50 M HCl at 40 ℃. Potentiodynamic polarization, linear polarization resistance corrosion rate and electrochemical impedance spectroscopy measurements were used for this study. Experimental results showed that, the inhibition efficiency increases with increasing the surfactant concentration, getting maximum inhibition efficiency ranged between 97.10 and 99.61% at 400 ppm. Potentiodynamic polarization curves showed that, the three compounds act as mixed type. The adsorption of investigated surfactants obeyed the Langmuir adsorption isotherm, and the thermodynamic parameters were calculated and discussed. Obvious correlation was found between the corrosion inhibition efficiency and the quantum chemical parameters. The obtained theoretical results have been adapted with the experimental data.