Corrosion inhibition and adsorption features of novel bioactive cationic surfactants bearing benzenesulphonamide on C1018-steel under sweet conditions: Combined modeling and experimental approaches

In this report, three novel sulphonamides based cationic surfactants have been produced, and their structure configurations were clarified by various spectroscopic approaches (¹³C and ¹H NMR). The corrosion protection characteristics of the as-prepared compounds for C1018-steel in carbon dioxide saturated 3.5% NaCl has been inspected and categorized by weight loss, Tafel polarization (PDP), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS), field emission-scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX) methods. Furthermore, conductivity and surface-active features were applied to examine their micellization and adsorption. The outcomes exhibited that these bioactive inhibitors at low doses had a worthy protection capacity on C1018-steel corrosion under sweet conditions ranged from 94.5 to 99.5% at 5 × 10⁻⁴ M additive concentration. PDP profiles display that the as-prepared surfactants were mixed inhibitors, and their adsorption followed the Langmuir isotherm model. FESEM, EDX, and XPS examinations demonstrated the formation of a protecting film adsorbed surfactant at metal/medium interface. DFT calculations, Monte Carlo (MC) simulations, molecular electrostatic potential (MEP), Fukui indices, and Mulliken atomic charges were accomplished to support empirical outcomes, and deliver suitable insight into the adsorption features and the corrosion inhibition mechanisms of the titled surfactants.