Chapter21 - Amino acids as green corrosion inhibitors

Abstract

Amino acids and their derivatives are extensively investigated as green corrosion inhibitors for different metal and electrolyte systems. Their corrosion inhibition performances are tested using various experimental and computational techniques. They serve as effective and environmental friendly alternatives for traditional toxic corrosion inhibitors. Potentiodynamic polarization measurement reveals that most of the amino acids and their derivatives become effective by suppressing both anodic and cathodic Tafel reactions without causing any significant variation in the value of corrosion potential, Ecorr. They act as mostly mixed-type corrosion inhibitors. Amino acids and their derivatives behave as interface-type corrosion inhibitors as they increase the values of charge transfer resistance (Rct) for the corrosion process. The adsorption of amino acids and their derivatives mostly follows the Langmuir adsorption isotherm. Adsorption mechanism of corrosion inhibition using amino acids and their derivatives has also been supported by surface investigations. DFT and MD (or MC) simulation studies are widely used to demonstrate the nature and effectiveness of interactions between these compounds and metallic surface. These analyses show that most of the amino acids and their derivatives spontaneously interacted through donor-acceptor interactions.