Anti-Corrosive Behaviour of Pennisetum typhoideum (Bajra) Leaf Extract Against Mild Steel in Acidic Conditions

Abstract

The corrosion of metals and their alloys has prompted an increase in research efforts to lessen the harm caused by the corrosion process. The study analyses the ability of Bajra (Pennisetum typhoideum) leaf extract to suppress corrosion on metal in 0.1 N HCl solutions using thermometric and weight loss techniques. At all extract concentrations, it was shown that the leaf extract efficiently prevents mild steel corrosion. The findings of mass loss measurements indicate that inhibition efficiency increases with inhibitor concentration. Based on thermodynamic considerations, the extract\'s adsorption is exothermic and spontaneous. From the results and findings of the study, a physical adsorption mechanism is proposed for the adsorption of ethanol extract of Bajra leaf extract on mild steel surface. The inhibitory efficiency was projected using certain methods at 298K, 308K, and 318K temperatures. As the extract\'s concentration rose, the inhibition effectiveness rose as well, demonstrating the leaf extract\'s inhibitory ability. The thermodynamic variable demonstrates that physisorption was the mechanism of inhibition. Therefore, the current research shows a new, ecologically safe, and effective corrosion inhibitor for protecting mild steel surfaces in acidic environments.

Introduction

• Corrosion is a natural process that causes refined metals to revert to their ore state.

• It leads to major economic losses, structural failures, and even industrial disasters.

• Corrosion costs globally amount to about 5% of world GDP; India loses around ?2 trillion/year due to corrosion.

???? Green Inhibitors as a Solution

• Traditional corrosion inhibitors are often toxic and environmentally harmful.

• Green inhibitors from plant extracts offer a biodegradable, eco-friendly, and effective alternative.

• Plant compounds like alkaloids, flavonoids, and phenols can adsorb onto metal surfaces, forming a protective layer against corrosion.

???? About the Plant: Pennisetum typhoideum

• Commonly known as pearl millet, widely grown in western India.

• Rich in phytochemicals and minerals.

• Leaves contain bioactive compounds with antimicrobial and antioxidant properties.

• Study focuses on using alcoholic leaf extract as a green inhibitor.

???? Methodology

1. Extraction: Leaves dried, powdered, and extracted with 95% ethanol using Soxhlet method.

2. Weight Loss Tests: Mild steel samples immersed in 0.1 N HCl with different extract concentrations (50–500 ppm).

3. Electrochemical Analysis: Evaluated corrosion rate, inhibition efficiency, and surface coverage.

4. Isotherm Studies: Langmuir adsorption isotherm best fit the data, indicating monolayer adsorption.

5. Activation Energy (Ea): Calculated using the Arrhenius equation to study temperature effects.

???? Key Results

• Inhibition Efficiency increased with concentration:

  • Up to 84.71% inhibition at 500 ppm after 24 hours.

• Corrosion rate decreased as concentration increased.

• Langmuir Isotherm showed good linearity with the data.

• Surface coverage (θ) and inhibitor efficiency (IE%) improved with time and concentration.

• At higher temperatures, inhibition efficiency decreased, suggesting desorption of inhibitor from the metal surface.

• Activation energy was higher in inhibited solutions, indicating a protective barrier formed by the extract.

???? Data Highlights (after 24 hrs at 298 K)

• At increasing temperatures, IE% reduced slightly, confirming the physical nature of adsorption.

Conclusion

The difficult fight against corrosion demands creative preventive strategies. The safety and environmental advantages of green corrosion inhibitors, especially those made from plants, are drawing a lot of attention. They have a clear benefit over conventional inhibitors and are safer to handle and less harmful to the environment. A more comprehensive and efficient corrosion inhibition mechanism is produced by the synergistic action of plant extracts\' intrinsic chemical diversity. In present study, the alcoholic leaves extracts of Pennisetum typhoideum are found to be influential inhibitor in acid media giving up to 84.71% efficiency at higher concentration (500ppm) at given temperature 298 K and can be safely used without toxic effects and pollution.

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Copyright

Copyright © 2025 Kumawat Y, Mathur P, Sharma A. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.