Inhibitory effect of Senecio anteuphorbium as green corrosion inhibitor for S300 steel

Abstract

The present work proposes the study of the extract of Senecio anteuphorbium (SA) as green corrosion inhibitor. This inhibitory effect of SA extract on the corrosion of S300 steel in hydrochloric acid 1 M has been evaluated by using the potentiodynamic polarization and electrochemical impedance spectroscopy. From the outcome of the polarization curves, SA extract acts as mixed-type inhibitor. The inhibition efficiency increased with the extract concentration increase to achieve a maximum of 91% at 30 mg/L. The adsorption of the inhibitor on the steel surface follows Langmuir isotherm and the values of activation energy suggested that the adsorption of inhibitor is a physical–chemical adsorption. Kinetic parameters such as enthalpy, activation energy and entropy were determined and discussed. The surface morphology of steel was observed before and after adding inhibitor by Fourier transform infrared spectroscopy. The changes in contact angles identified the formation of the protective film. Scanning electron microscopy and energy-dispersive X-ray revealed the adsorption of the same organic compounds of the extract on the interface metal/solution.