Green Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Fruit Peel Extract of Citrus aurantifolia

International Journal of Chemistry | Vol. 6, No. 12, December 2015 | pp. 89–96

DOI: 10.46882/2015/IJC/000087

Article Type: Original Research Paper

Title: Green Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Fruit Peel Extract of Citrus aurantifolia

Names of Authors: M. A. Haruna¹, S. Swaminathan²*

Authors’ Affiliations:
¹Department of Chemistry, Federal University of Technology, Minna, Nigeria.
²Department of Chemistry, Indian Institute of Technology, Madras, India.

Abstract: The utilization of toxic synthetic chemical inhibitors in industrial acid descaling operations creates substantial environmental and safety hazards, driving research into sustainable green alternatives. The corrosion mitigation performance of the methanolic fruit peel extract of Citrus aurantifolia (CA-Extract) on carbon steel in 1.0 M HCl was investigated via gravimetric weight loss and electrochemical test protocols. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements were recorded across varying inhibitor dosages (0.2 to 2.0 g/L) and system temperatures (303 to 333 K). Weight loss metrics revealed that protection efficiency increased with extract concentration, peaking at 92.5% at a dose of 2.0 g/L. Polarization diagrams established that CA-Extract functions as a mixed-type inhibitor, suppressing both anodic iron dissolution and cathodic hydrogen gas evolution pathways. EIS scans confirmed that charge-transfer resistance (Rct) increased with higher extract amounts, indicating the formation of a robust organic protective film on the steel face. The adsorption behavior of the bioactive compounds conformed to the Langmuir isotherm model, yielding a negative standard free energy of adsorption (delta G°ads = -21.4 kJ/mol), denoting a spontaneous physical adsorption mechanism driven by the presence of rich plant flavonoids.

Keywords: Carbon steel; Corrosion inhibition; Citrus aurantifolia; Electrochemical impedance spectroscopy; Polarization; Adsorption isotherm

Manuscript Timeline: Received: April 18, 2015; Revised: June 05, 2015; Accepted: July 12, 2015; Published: December 04, 2015.

Citation: Haruna, M. A., & Swaminathan, S. (2015). Green Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Fruit Peel Extract of Citrus aurantifolia. International Journal of Chemistry, 6(12), 89–96.

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