Preparation of zwitterionic ionic surfactants-based sulphonyl for steel protections: Experimental and theoretical insights

Abstract

Abstract Designating an organic inhibitor with a specific chemical structure that actively participates in steel protection by increasing adsorption on the steel surface. Based on that, we synthesized three zwitterionic surfactants based on azomethine with different hydrophobic chain lengths labeled ZWSO, ZWSD, and ZWSH. The presence of azomethine group, electrons, and heteroatoms in the zwitterionic surfactant’s amphipathic structure helped to improve C-steel protection. Their inhibitory activity toward steel corrosion was investigated utilizing electrochemical impedance spectroscopy (EIS), gravimetrical, and potentiodynamic polarization techniques. Importantly, the surfactant tail influenced corrosion inhibition performance; as surfactant tail length increased, so did inhibition efficiency due to increased adsorption affinity. The inhibition efficiencies of ZWSO, ZWSD, and ZWSH are 87.15, 89.82, and 91.36%, respectively. Tafel data clarified that ZWSO, ZWSD, and ZWSH inhibitors behave as mixed-type inhibitors following the modified Langmuir isotherm. The inhibitors can adsorb physiochemically on the steel surface with ∆G ads ranges from −38.48 to −44.6 kJ mol−1. The SEM confirms that the morphology of C-steel becomes smoother because of inhibitor adsorption. The DFT and MCs output data supported the experimental performance of the tested ZWSO, ZWSD, and ZWSH inhibitors and especially their dependence on surfactant tail length.