Electrochemical, Thermodynamic and Adsorption Studies of (+)-Catechin Hydrate as Natural Mild Steel Corrosion Inhibitor in 1 M HCl

The inhibiting action of (+)-catechin hydrate on the corrosion of mild steel in hydrochloric acid has been studied. The results from weight loss, Tafel polarization and electrochemical impedance measurements consistently identify (+)-catechin hydrates as a good inhibitor. Polarization curves indicate that (+)-catechin hydrate act as mixed type inhibitor with predominant inhibition at anodic site. Impedance spectroscopy revealed that the corrosion of mild steel in hydrochloric solution was influenced to some extent by charge transfer. The inhibition efficiencies (IE %) of (+)-catechin hydrate was decreased exponentially with the temperatures. Surface analyses via scanning electron microscope (SEM) show a significant morphological improvement on the mild steel surface in addition of (+)-catechin hydrate. The inhibitive action of (+)-catechin hydrate follows the Langmuir adsorption model.