ISSN 2305-6894

Anodic behavior of aluminum in α-alanine aqueous solutions at various pH values

Voronezh State University, Universitetskaya pl. 1, Voronezh, 394006 Russian Federation

Abstract: The effect of α-alanine on aluminum anodic behavior in its solutions with pH values from 4.2 to 8.5 has been studied. It has been found that, depending on the pH, the amino acid exhibits a dual effect. On the one hand, α-alanine zwitter-ions (pH 4.2–5.6) behaving like an inhibitor slow down the anodic process, so aluminum is in a stable passive state at these pH values in the vicinity of the isoelectric point of the amino acid. The probable reason of the observed effect is that strong intermolecular hydrogen bridges that are formed between the amino and carboxy groups in the amino acid zwitter-ions predominate over interactions with the oxidized aluminum surface. On the other hand, it has been shown that the α-alanine anions formed at pH = 8.5 stimulate pit formation on aluminum surface in these solutions. Based on literature and experimental data, a dissociative mechanism of pit formation on aluminum in the systems in question is suggested.

Keywords: pit formation, inhibition, aluminum, α-alanine, pH

Int. J. Corros. Scale Inhib., , 2, 122-131 PDF (886 K)
doi: 10.17675/2305-6894-2013-2-2-122-131

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