Electrochemical Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Seed Extract of Piper guineense

International Journal of Chemistry | Vol. 5, No. 4, April 2014 | pp. 25–32

DOI: 10.46882/2014/IJC/000067

Article Type: Original Research Paper

Title: Electrochemical Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Seed Extract of Piper guineense

Names of Authors: M. A. Haruna¹, S. Rajagopal²*

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 corrosion inhibitors in industrial acid descaling operations poses significant environmental risks, driving research into sustainable green alternatives. The corrosion mitigation performance of the methanolic seed extract of Piper guineense (PG-Extract) on carbon steel in 1.0 M HCl solutions was monitored via gravimetric weight loss and electrochemical measurement protocols. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves were recorded across varying inhibitor dosages (0.2 to 2.0 g/L) and temperatures (303 to 333 K). Weight loss metrics revealed that protection efficiency increased with extract concentration, peaking at 93.5% at a dose of 2.0 g/L. Polarization diagrams established that PG-Extract functions as a mixed-type inhibitor, suppressing both anodic iron dissolution and cathodic hydrogen gas evolution. EIS scans confirmed that charge-transfer resistance (Rct) increased with higher extract amounts, indicating the formation of a robust organic protective film on the metal 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 = -22.4 kJ/mol), denoting a spontaneous chemisorption mechanism driven by the presence of piperine alkaloids.

Keywords: Carbon steel; Corrosion inhibition; Piper guineense; Electrochemical impedance spectroscopy; Polarization; Adsorption isotherm

Manuscript Timeline: Received: April 18, 2013; Revised: June 05, 2013; Accepted: July 12, 2013; Published: April 04, 2014.

Citation: Haruna, M. A., & Rajagopal., S. (2014). Electrochemical Corrosion Inhibition of Carbon Steel in Hydrochloric Acid Using Seed Extract of Piper guineense. International Journal of Chemistry, 5(4), 25–32.

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