Comparative Investigation of the Corrosion Protection Efficacy of Spondias mombin Leaf Extracts on AA2024 Alloy and Low Carbon Steel in Acidic Medium

The anti-corrosive property of Spondias mombin (SM) leaves extract on low carbon steel (LCS) and aluminium alloy (AA2024) in 1M HCl solution was investigated using gravimetric and electrochemical methods. The results obtained from the weight loss experiment performed at various temperatures (30, 45, and 60 0C) show that the inhibition efficiency values decreased with temperature rise but increased as the inhibitor concentrations were increased. At 30 0C, optimum inhibition efficiency (IE) of 80.11% and 78.06% were obtained for LCS and AA2024 respectively. The potentiodynamic polarization (PDP) result reveal that an optimum IE values of 92.1% and 74.0% were respectively obtained for LCS and AA2024 while the electrochemical impedance spectroscopy (EIS) data show IE values of 91.5% and 74.5% for LCS and AA2024 respectively. In all cases, the values of inhibition efficiency obtained for LCS were greater than those obtained for AA2024. This implies that SM leaf extracts offers a better protective-layer on LCS surface compared to the AA2024 alloy in the acidic medium. The isotherm study reveal that Langmuir model best fitted the adsorption of the leaf extracts on LCS while Freundlich model best fitted the leaf extracts adsorption on AA2024 surface.