A comprehensive experimental and theoretical perspective of novel triazole-based pyridine and quinoline derivatives for corrosion protection of carbon steel in sulfuric acid solution

Abstract

Abstract Herein, we synthesized two novel triazole compounds (KB1 and KB2). Their efficiency in inhibiting corrosion of carbon steel (CS) in 0.5 M H 2 SO 4 was evaluated using open circuit potential (OCP) vs. time, potentiodynamic polarization (PP), electrochemical impedance spectroscopy (EIS), surface characterization methods, and computational studies. Based on EIS, the corrosion protection capacities of KB1 and KB2 increased with increasing concentration, reaching 86.9% and 92.4% at 9 × 10 − 5 M at 298 K for KB1 and KB2, respectively, which are consistent with the findings obtained via PP. The PP curves imply that KB1 and KB2 act as mixed-type inhibitors. Meanwhile, their adsorption on the surface of CS obeyed the Langmuir isotherm. Using EIS and PP approaches, the effect of temperature on corrosion behavior was examined. As the temperature increased from 298 to 318 K, the efficacy of the inhibitors improved, then decreased at 328 K. This suggests that KB1 and KB2 may desorb from the CS at 328 K. The activation and adsorption parameters were computed and discussed. The effect of immersion time on CS corrosion was documented. The R ct values of the KB2 compound peaked at 2770.0 Ω cm 2 after 6 h of immersion, later declining to 2685.0 Ω cm 2 after 93 h, thus evidencing the enhanced stability of the inhibitor’s protective layer on the CS surface. Additionally, the steel surface was found to be positively charged in the H 2 SO 4 solution, as indicated by the potential of zero charge (PZC) measurements using EIS. Surface morphology analysis using Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) demonstrated the formation of a protective layer with a high degree of coverage at 9 × 10 − 5 M. The test solutions were analyzed via UV-visible spectroscopy to determine whether complex formation between inhibitor molecules and Fe 2+ ions is possible. The mechanism of inhibition was better understood via quantum chemical indices (based on DFT). The configurational adsorption performance of KB1 and KB2 on the Fe (110) surface was investigated via Monte Carlo (MC) simulation, which revealed that inhibitors adsorbed on the Fe surface in a flat orientation. These results are thought to have some bearing on the sensible development of potent inhibitors for acidic corrosion.

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