Evaluating the efficacy of newly synthesized amino acid derivatives as corrosion inhibitors in acidic solutions

Abstract

Three benzimidazole derivatives, with tryptophan (BIT), tyrosine (BIY), and histidine (BIH) amino acid units, have remarkable protective properties as eco-friendly corrosion inhibitors for steel under severe acidic conditions. At a temperature of 303 K, the corrosion inhibition efficiency of BIT, BIY, and BIH at a concentration of 10 mM is 90.09 %, 92.53 %, and 93.43 %, respectively. Electrochemical tests indicate that the adsorption of these substances on the substrate leads to an increase in charge transfer resistance and interfacial electric double layer thickness. This effectively hinders the dissolution of metal and the evolution of hydrogen. The analysis of the surface structure and appearance using SEM-EDS indicates that the inhibitors have the ability to create a protective coating through both chemical and physical bonding, effectively protecting the metal from corrosive substances. Theoretical calculations, such as Density Functional Theory (DFT) and Natural Bond Orbital (NBO) analysis, along with FUKUI analysis, help identify active sites and adsorption configuration. This enhances our understanding of the corrosion mitigation mechanism. These findings align with the experimental conclusion that the formation of a stable protective film contributes to superior inhibition performance against acidic corrosion conditions.