Some aspects of the of the mechanism of C1018 steel protection in hydrochloric acid solutions by triazole derivatives

• M.D. Plotnikova, A.D. Shitoeva, A.D. Solovyev, A.N. Bakiev and A.B. Shein

Perm State National Research University, st. Bukireva 15, 614068, Perm, Russian Federation

Abstract: The effect of 3-phenyl-1H-1,2,4-triazole-5-thiol, 24-methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol, and 4-amino-4H-1,2,4-triazole-3,5-dithiol on the corrosion of C1018 steel in acid media (1 M and 5 M HCl) has been studied by weight loss tests, potentiodynamic polarization and electrochemical impedance spectroscopy. These studies have shown that 4-methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol is more effective in 1 M HCl, but 4-amino-4H-1,2,4-triazole-3,5-dithiol is better in 5 M HCl. The polarization measurements have shown that all the inhibitors studied are cathodic-type inhibitors in the HCl media in the temperature range of 293–353 K. 3-Phenyl-1H-1,2,4-triazole-5-thiol remained efficient in the temperature range of 293–353 K both in 1 M hydrochloric acid and in 5 M HCl solution due to chemical adsorption of inhibitor molecules on the metal surface. 4-Methyl-5-((4-phenyl-1H-1,2,3-triazol-1-yl)methyl)-4H-1,2,4-triazol-3-thiol and 4-amino-4H-1,2,4-triazole-3,5-dithiol in 5 M HCl solution lose their protective properties with an increase in temperature, which is associated with a change in the nature of adsorption. The nature of adsorption was assessed based on the calculation of the activation energy of the corrosion process in the presence of the compounds studied. Furthermore, the adsorption obeys the Langmuir isotherm at room temperature. The negative standard Gibbs energy of adsorption in the presence of triazoles suggests the chemisorption of its molecules on the steel surface.

Keywords: mild steel, acid corrosion, triazole, inhibitor, potentiodynamic polarization, activation energy, electrochemical impedance spectroscopy, adsorption

Int. J. Corros. Scale Inhib., 2023, 12, no. 2, 511-530
doi: 10.17675/2305-6894-2023-12-2-8

Download PDF (Total downloads: 200)

Back to this issue content: 2023, Vol. 12, Issue 2 (pp. 366-810)