Exploring Ginkgo biloba extract's green corrosion inhibition effects on Q235 steel in H2SO4 environments

Abstract

The corrosion inhibition properties of Ginkgo biloba extract on Q235 steel in 0.5 M H2SO4 solution were comprehensively investigated using weight loss measurements, electrochemical techniques, surface characterization, and quantum chemical calculations. The results demonstrate that Ginkgo biloba extract acts as an effective green corrosion inhibitor, with inhibition efficiencies reaching up to 96.54% at a concentration of 0.7 g/L. The inhibition efficiency increased with increasing extract concentration and temperature. FTIR and LC/MS analyses revealed that the extract contains various phytochemical constituents, including flavonoids, terpenoids, and other polyphenolic compounds, which contribute to its corrosion inhibition properties. The adsorption of the extract compounds on the steel surface followed the Langmuir adsorption isotherm, with a negative value of the standard free energy of adsorption, indicating a spontaneous and stable adsorption process involving both physisorption and chemisorption. SEM and XPS analyses confirmed the formation of a protective film by the adsorbed extract compounds, which acts as a barrier, preventing the direct contact between the aggressive solution and the steel substrate. The film also alters the wettability of the metal surface, making it more hydrophobic and further enhancing the corrosion inhibition efficiency. Quantum chemical calculations showed that flavonoids, particularly quercetin, contribute significantly to the corrosion inhibition performance due to their high reactivity, strong dipole moment, and stable adsorption on the Fe(110) surface. These findings provide valuable insights into the development of sustainable and eco-friendly corrosion inhibitors for the protection of metal structures in acidic environments.