Corrosion resistance of carbon steel in weak acid solutions in the presence of l-histidine as corrosion inhibitor

This paper presents the inhibitory properties of l-histidine on the corrosion of carbon steel in weak acid media containing acetic acid/sodium acetate. The inhibition efficiencies obtained by weight loss measurements are in good agreement with values given by Tafel method and electrochemical impedance spectroscopy. The adsorption of l-histidine obeys the Langmuir isotherm and the negative values of Gibbs energy indicate the nature of interactions between inhibitor molecules and metal surface. Further, the inhibition effect was studied using scanning electron microscopy and energy dispersive X-ray analysis.

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► Histidine has good inhibition efficiency for carbon steel in weak acid media.
► Electrochemical behavior of histidine shows that it is stable in studied media.
► Adsorption isotherm of histidine on carbon steel proves a spontaneous process.
► Optic and scanning electron microscopy was used to study the surface morphology.