Study on corrosion inhibition behavior and adsorption mechanism of novel synthetic surfactants for carbon steel in 1 M HCl solution

The corrosion inhibition behavior and adsorption mechanism of three novel synthetic surfactants in 1 M HCl solution on carbon steel were investigated. The PP results confirmed that all the synthetic surfactants behave as mixed-type inhibitors, while the EIS results validated the existence of a protective layer by the adsorption of inhibitor molecules on the carbon surface. T₃ was observed to offer the highest inhibition efficiency (η_w, 96.28%) at 1 mM by the static weight loss measurements due to two different hydrophobic chains which form a more compact film with the crosswise arrangement. SEM/EDS and XPS results revealed the formation of the surfactants film on the carbon steel surface. Molecular dynamics simulation (MD) was further executed to determine the adsorption mechanism in molecular level insights. In addition, a linear correlation between surface activity (γ) and corrosion inhibition efficiency (η_w) was verified. The adsorption of the prepared surfactants followed the Freundlich isotherm at different concentration ranges. Moreover, the bilayer/multilayer adsorption mechanism was also proposed and confirmed by experimental, adsorption isotherm studies and MD. Hence, both MD simulations and experimental results revealed the analogous inhibition with the order follows: T₃ > T₂ > T₁.