Abstract

ENNOURI, A.; LAMIRI, A.  and  ESSAHLI, M.. Corrosion Inhibition of Aluminium in Acidic Media by Different Extracts of Trigonellafoenum-graecum L Seeds. Port. Electrochim. Acta [online]. 2017, vol.35, n.5, pp.279-295. ISSN 0872-1904.  https://doi.org/10.4152/pea.201705279.

The corrosion inhibition of aluminum by the extract of Trigonellafoenum-graecum L was studied in a hydrochloric acid 1 M solution using electrochemical polarization measurements and electrochemical impedance spectroscopy (EIS). Three organic solvents, pentane, dichloromethane (DCM) and ethanol, of different polarities, were tested. An inhibition efficiency of 86.6 %, 84.41 %, and 75.77 % was obtained by the addition of 1400 ppm of the extract using three solvents: DCM, ethanol and pentane, respectively. The potentiodynamic curves show that the decrease of aluminum corrosion in the presence of the fenugreek extract in a HCl 1 M solution mainly acts by a mixed process with an anodic tendency for both extracts with ethanol and with pentane; on the other hand, the extract with DCM showed a cathodic tendency. The temperature effect on the corrosion of aluminum indicates that the inhibition efficiency of the natural substance decreases with an increase in temperature. The inhibition efficiency values obtained from the polarization curves are in good agreement with those of EIS.

Keywords : aluminum, inhibition; corrosion; fenugreek; extract; solvent; hydrochloric acid.

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