Functionalised novel gemini surfactants as corrosion inhibitors for mild steel in 50 mM NaCl: experimental and theoretical insights

Abstract

Novel gemini surfactants functionalised with oxygen atom and ester groups were synthesized and characterised by NMR methods. The corrosion inhibiting properties of the synthesized compounds were investigated by potentiodynamic polarization, linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). The results show that inhibition efficiency depends on concentration and the ability to create micelles in aqueous environment, with the highest inhibition efficiency being at around critical micelle concentration (CMC). Furthermore, their inhibition effect was compared against a well-known, commercially available, corrosion inhibitor (benzotriazole) and found to be better for the novel compounds under study in this work. Moreover, the Langmuir adsorption isotherm was found to be suitable for correlating the experimental results with the proposed mechanism of protection. Theoretical studies were based on Density Functional Theory (DFT) and correlation between experimental and theoretical results was determined. These results open perspectives for the application of these new compounds in corrosion protection.