Assessment of the Amino Acid L-Histidine as a Corrosion Inhibitor for a 1018 Carbon Steel in Aqueous Sodium Chloride Solution
Milena Jacinto da Silva Moura,
Roberta Bastos Vasques,
Saulo Jose de melo Magalhães,
Francisco Wagner de Queiroz Almeida Neto,
Pedro de Lima Neto,
Luís Paulo Mourão dos Santos,
Mauro Andres Cerra Florez,
Gemma Fargas Ribas,
Samuel Lucas Santos Medeiros,
Francisco Carlos Carneiro Soares Salomão,
Eduardo Bedê Barros,
Walney Silva Araújo
Affiliations
Milena Jacinto da Silva Moura
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Roberta Bastos Vasques
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Saulo Jose de melo Magalhães
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Francisco Wagner de Queiroz Almeida Neto
Science and Technology Center of the Inhamuns Region, Ceara State University Education, Taua 60000-000, Brazil
Pedro de Lima Neto
Department of Analytical Chemistry and Physical Chemistry, Federal University of Ceará, Fortaleza 60440-900, Brazil
Luís Paulo Mourão dos Santos
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Mauro Andres Cerra Florez
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Gemma Fargas Ribas
CIEFMA, Department of Materials Science and Engineering, Escola d’Enginyeria de Barcelona Est (EEBE), Universitat Politècnica de Catalunya, 08019 Barcelona, Spain
Samuel Lucas Santos Medeiros
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
Francisco Carlos Carneiro Soares Salomão
Science and Technology Center—Physics Course, Itaperi Campus, Ceará State University, Fortaleza 62930-000, Brazil
Eduardo Bedê Barros
Department of Physics, Federal University of Ceará, Fortaleza 60455-760, Brazil
Walney Silva Araújo
Graduate Program in Materials Science and Engineering, Federal University of Ceará, Fortaleza 60440-900, Brazil
The amino acid L-histidine, which has an imidazole ring, was investigated as a corrosion inhibitor for AISI 1018 carbon steel in chloride solution based on the effectiveness of inhibitors containing imidazole in their composition. A neutral environment was chosen for this study due to the scarcity of research on this amino acid in this environment type. Concentrations of 250, 500, and 1000 ppm were evaluated. Various methods were used to determine inhibition effectiveness, including mass loss, open circuit potential, linear potentiodynamic polarization, and electrochemical impedance spectroscopy. For mass loss, the inhibition efficiency varied from 83 to 88% according to the increase in concentration. For the electrochemical tests, the efficiency variation ranged from 62 to 90% with increasing amino acid concentration. Furthermore, a simulation analysis using quantum chemical calculations within the scope of Density Functional Theory (DFT) revealed that histidine’s nucleophilic character is crucial for its corrosion inhibitory capacity in an aqueous medium at pH 7. The inhibition efficiency increased with increasing concentration in a neutral medium, following the Langmuir isotherm for the adsorption of L-histidine. Additional studies were carried out using Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TGA). Analysis of the substrate surface by scanning electron microscopy (SEM) showed greater preservation with the addition of L-histidine, confirming its adsorption on the steel. Atomic Force Microscopy (AFM) also demonstrated an improvement in surface roughness in the presence of amino acids compared to the medium without an inhibitor.
