Bioinhibition of Corrosion of Mild Steel in 1 M NaOH by Ethanolic Extract of Dialium guineense Leaves Using Different Corrosion Techniques
L. Emembolu, O. Achugbu, and O. Onukwuli (1-18)
Abstract
This work assessed the efficacy of Dialium guineense leaf extract (DGE) in corrosion inhibition of mild steel in 1 M NaOH medium utilizing various corrosion methods like gravimetric, potentiodynamic polarization techniques, etc. The leaf extract was characterized by Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry, and phytochemical analysis. Polished mild steel after being immersed in the leaf extract was characterized by scanning electron microscopy methods to assess the surface effect of the inhibitor on the mild steel. Gravimetry, electrochemical impedance spectroscopy, and potentiodynamic polarization methods were employed in studying the adsorption, kinetics, and thermodynamics behavior of corrosion inhibition of mild steel at different temperatures (303 K, 323 K, and 343 K) and varied inhibitor concentrations (0.2, 0.4, 0.6, 0.8, and 1.0 g/L ). Response surface methodology was employed to optimize the inhibition efficacy. The gravimetric results revealed that the DGE was more efficient at higher concentrations but less efficient at lower temperatures. The potentiodynamic polarization results, on the other hand, indicate that the DGE is a mixed-type inhibitor. Electrochemical impedance spectroscopy results revealed that the addition of the inhibitor increased the charge-transfer resistance of the corrosion process and hence the suppression performance. The DGE exhibited good corrosion resistance performance; hence, it can serve as a suitable corrosion inhibitor for mild steel in NaOH and other alkaline media.