Nature Environment and Pollution Technology

M. Shyamala ¹, A. Arulanantham ¹

Affiliations
1 Department of Chemistry, Government College of Technology, Coimbatore-641 013, T. N., IN

Abstract

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.

Keywords

Aegle marmelos, Corrosion Inhibitor, Langmuir Isotherm, Aegeline.

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M. Shyamala ¹, A. Arulanantham ¹

Affiliations
1 Department of Chemistry, Government College of Technology, Coimbatore-641 013, T.N., IN

Abstract

The aqueous extract of Ocimum sanctum as corrosion inhibitor on mild steel in 1 N hydrochloric acid was studied using the weight loss method, gasometric, potentiodynamic polarization and impedance method. The maximum inhibition efficiency was 99.6 % in the optimum concentration of the extract 6 % in v/v. Similarly, in gasometric method, maximum efficiency was 98.6% in the same concentration. It was confirmed by potentiodynamic polarization and impedance methods, which showed a maximum efficiency of 99.7% and 97.9% respectively in the same concentration. The effect of immersion time from 3 hrs to 24 hrs at 30°C on corrosion inhibition of mild steel in 1N HCl in the presence of the optimum concentration of the inhibitor (6 % in v/v) revealed that the extract of Ocimum sanctum has maximum efficiency of 99.6% in 3 hours immersion time. Potentiodynamic polarization studies indicated that the plant extract behaves as mixed type inhibitor. The results show that 6% in v/v aqueous extract of the leaves of Ocimum sanctum could serve as an effective inhibitor on the corrosion of mild steel in 1 N hydrochloric acid medium.

Keywords

Corrosion inhibition, Ocimum sanctum, Plant extract, Mild Steel Corrosion, Polarization Curves.

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