Cinnamon leaf 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 L−1 extract shows excellent inhibition efficiency up to 90% after 24 h immersion in all acid concentrations tested. The polarization resistance of mild steel specimens obtained by EIS measurements is found to be increased and the current density obtained by potentiodynamic polarization studies is decreased significantly in the presence of the extract. Moreover, significant increase in the charge transfer resistance of mild steel specimens by more than a factor of 10 in the presence of the inhibitor is achieved at lower HCl concentrations of 0.1 mol L−1 and 0.5 mol L−1. 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.