An experimental and theoretical study of two pyridinium salt derivatives as API 5L Grade B steel corrosion inhibitors in H₂SO₄ solution

• B. Mezhoud^1,2, A. Bouraiou¹, M.E. Said^1,3, A. Kherrouba⁴, D. Hannachi^5,6 and A. Chibani¹

¹ Unit for Environmental Chemistry and Molecular Structural Research, CHEMS, University of Frères Mentouri Constantine 1, Constantine, Algeria
² Department of Chemistry, Faculty of Exact Sciences and Computer Science, Mohamed Sedik Ben Yahia University, B.P 98 Ouled Aissa, 18000, Jijel, Algeria
³ Faculty of Technology, Mohamed Boudiaf University, B.P 166 Ichbelia, 28000, M’sila, Algeria
⁴ Materials Chemistry Laboratory Constantine, University of Frères Mentouri Constantine 1, Constantine, Algeria
⁵ Laboratory of Electrochemistry, Molecular Engineering and Redox Catalysis (LEIMCR), Department of Basic Education in Technology, Faculty of Technology, University Ferhat Abbas, Setif-1, Algeria
⁶ Department of Chemistry, Faculty of Mterial Science, University of Batna-1, Batna, Algeria

Abstract: The inhibition of API 5L Grade B steel corrosion in sulfuric acid solution in the presence of some pyridinium salt derivatives such as 1,1′-methylenebis(pyridin-1-ium)bromide (pyridinium salt 1) and 1,1′-(ethane-1,2-dyl))bis(pyridin-1-ium)bromide (pyridinium salt 2) was conducted using weight loss techniques, potentiodynamic polarization methods, electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM) and theoretical calculations. Various parameters were determined and discussed to fully understand the mode of action of these compounds, including thermodynamic activation, adsorption, and quantum chemical parameters. The results obtained by all techniques revealed that these derivatives are suitable inhibitors for this type of steel in sulfuric acid solutions. In addition, the inhibition efficiency increases with pyridinium salt concentration and temperature. The polarization curves show that both pyridinium salts are mixed-type inhibitors. Electrochemical impedance spectroscopy (EIS) indicates that charge transfer controls the corrosion process of steel in the absence and presence of compounds. The adsorption of each compound occurs via electrostatic and chemical bonds and obeys Langmuir’s adsorption isotherm. AFM images demonstrate that these salts protect this steel in H₂SO₄ solution. Theoretical calculations indicate a correlation between the experimental and quantum parameters.

Keywords: steel corrosion, sulfuric acid solution, pyridinium salts, potentiodynamic polarisation

Int. J. Corros. Scale Inhib., 2024, 13, no. 3, 1520-1540
doi: 10.17675/2305-6894-2024-13-3-9

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