Resumo

EL-ETRE, A.Y.  e  EL-TANTAWY, Z.. Inhibition of metallic corrosion using ficus extract . Port. Electrochim. Acta [online]. 2006, vol.24, n.3, pp.347-356. ISSN 0872-1904.

The inhibitive action of the extract of Ficus nitida leaves toward general and pitting corrosion of C-steel, nickel and zinc in different aqueous media was investigated. Weight loss measurements, potentiostatic and potentiodynamic polarization techniques were used in this study. It was found that the presence of ficus extract in the corrosive media (acidic, neutral or alkaline) decreases the corrosion rates of the three tested metals. The inhibition efficiency increases as the extract concentration is increased. The inhibition efficiency depends on the type of corroded metal and on the corrosive solution. It was also found that the presence of ficus extract in the chloride containing solution shifts the pitting potentials of the tested metals toward the noble direction. The inhibitive action of ficus extract is discussed in view of adsorption of its components, the poly aromatic compounds, friedelin, epifriedelanol and nitidol, on the metal surface. It was found that such adsorption follows Langmuir adsorption isotherm. The calculated values of the free energy of adsorption indicated that the adsorption process is spontaneous.

Palavras-chave : C-steel; nickel; zinc; corrosion inhibition; natural products; ficus.

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