Mechanism of corrosion behaviour of carbon steel in tartaric and malic acid in the presence of Fe2+ ion

The effect of (0.05 M) tartaric and malic acids on the corrosion behaviour of (0.5 C%) carbon steel in the absence or presence of Fe2+ ions at pH 2.8 was studied by measuring the corrosion potential and the corrosion rates by the galvanostatic polarization technique. The extent to which corrosion is promoted depends on the concentration of the Fe2+ ion. Tartaric acid has a more pronounced effect on the corrosion rate. The activation energy of hydrogen evolution was found to be 5.46 and 4.55 Kcal mol(-1) for tartaric and malic acid respectively. The activation energies for the overall corrosion process at the free corrosion process was found to be 5.6 and 5 Kcal mol(-1) for tartaric and malic acid respectively. These values are characteristic of a diffusion controlled process. (C) 1998 Elsevier Science S.A.