l-Tryptophan as green corrosion inhibitor for low carbon steel in hydrochloric acid solution

• Published in: Journal of materials science 2010-02, Vol.45 (4), p.979-986
• Main Authors: Fu, Jia-Jun, Li, Su-Ning, Cao, Lin-Hua, Wang, Ying, Yan, Lian-He, Lu, Lu-De
• Format: Article
• Language: English
• Subjects: Adsorption; Carbon steel; Cathodic polarization; Characterization and Evaluation of Materials; Chemical inhibitors; Chemistry and Materials Science; Classical Mechanics; Computer simulation; Corrosion; Corrosion inhibitors; Crystallography and Scattering Methods; Density functional theory; Hydrochloric acid; Inhibition; Iron; Low carbon steel; Low carbon steels; Materials Science; Pi-electrons; Polarization; Polymer Sciences; Solid Mechanics; Steel; Surface chemistry; Thermodynamics; Toy industry; Tryptophan; Weight loss
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-009-4028-0

The inhibition behavior of low carbon steel in 1 M HCl by l -tryptophan was investigated with weight loss experiment and Tafel polarization curve in the used temperature range (298–328 K). All the experimental results show that l -tryptophan has excellent corrosion inhibition performance and the most effective concentration of inhibitor is 1 × 10 −2  mol L −1 . The Tafel polarization curve results indicate that l -tryptophan acts more as a cathodic than anodic inhibitor. The adsorption of l -tryptophan on the surface of low carbon steel obeys the Langmuir adsorption isotherm, and the thermodynamic parameters were determined and discussed. The adsorption behavior of l -tryptophan at Fe surface (1 1 0) was also investigated by the molecule dynamics simulation method and density functional theory. The results indicated that the l -tryptophan could adsorb firmly on the Fe surface through the indole ring with π-electrons and nitrogen/oxygen atom with lone-pair electrons in its molecule.