Aegle marmelos as Effective Corrosion Pickling Inhibitor on Mild Steel in Hydrochloric Acid

In this study, the corrosion inhibition effect of aqueous extract of Aegle marmelos in 1N hydrochloric acid has been investigated by weight loss, gasometric, potentiodynamic polarization and impedance methods. The Aegle marmelos was found to be effective corrosion pickling inhibitor. The effect of immersion time revealed that the extracts of Aegle marmelos has maximum inhibition efficiency of 97.5 % in presence of an optimum concentration of 8 % v/v of the extract at 3 hours of immersion time. Similarly, in gasometric method, maximum efficiency was found to be 97.1 % in the same optimum concentration. It was confirmed by potentiodynamic polarization and impedance methods, which showed a maximum efficiency of 97.5 % and 96.6 % respectively in the concentration 8 % in v/v. Potentiodynamic polarization studies indicated that the plant extract behaves as mixed type inhibitor. The adsorption of Aegle marmelos follows Langmuir adsorption isotherm. The inhibition action is due to presence of the alkaloid aegeline in the leaves of Aegle marmelos. The protective film formed on the surface of the mild steel was confirmed by SEM studies.