Abstract

KUMAR, K.P. Vinod; PILLAI, M.S. Narayanan  and  THUSNAVIS, G. Rexin. Pericarp of the Fruit of Garcinia Mangostana as Corrosion Inhibitor for Mild Steel in Hydrochloric Acid Medium. Port. Electrochim. Acta [online]. 2010, vol.28, n.6, pp.373-383. ISSN 0872-1904.

The corrosion inhibition effect of acid extract of the pericarp of the fruit Garcinia mangostana on mild steel in hydrochloric acid medium is studied. Using weight-loss data, corrosion rate (CR) and thermodynamic parameters such as energy of activation for corrosion of mild steel (E), heat of adsorption of the inhibitors on the metal surface (Q) and change in free energy (∆G) are calculated.  Adsorption isotherm is also recorded between log C and θ. Electrochemical parameters are evaluated from AC impedance and Tafel polarization studies in the presence and absence of different concentrations of inhibitor. Infra-red spectra are recorded for the extract and the adsorption product to find out the changes in the functional group frequencies of the organic components of the extract. The surface morphological changes are analysed using the SEM images. The entire study shows that the pericarp extract of the fruit G. mangostana is a non-toxic, cost-effective corrosion inhibitor for mild steel in acid medium.

Keywords : corrosion; mild steel; G. mangostana; Tafel polarization; impedance; SEM.

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