Cinnamon Leaves Extract as an Effective Inhibitor for Mild Steel Corrosion in Pickling Bath Environments

Abstract Inhibition effect of acidic extracts of cinnamon leaves for mild steel corrosion in HCl solutions of different concentrations was investigated using mass loss measurements, electrochemical impedance spectroscopic (EIS) analysis and potentiodynamic polarization studies at ambient temperature. According to mass loss measurements, 60 g dm− 3 extract shows excellent inhibition efficiency up to 90% after 24 h immersion in all tested acid concentrations. The charge transfer resistance (Rct) of mild steel electrodes obtained by electrochemical impedance spectroscopic measurements is found to be increased and the current density obtained by potentiodynamic polarization studies is decreased significantly in the presence of the extract. These studies suggest that the inhibition effect observed is due to the adsorption of corrosion-resistive components of the cinnamon leaf extract on the mild steel surface, which follows the Langmuir adsorption isotherm.