Cationic Gemini Surfactants with a Bipyridyl Spacer as Corrosion Inhibitors for Carbon Steel

[Image: see text] In this work, cationic Gemini surfactants with different alkyl chain lengths (n = 8, 10, and 12) and a bipyridyl spacer were synthesized and tested as corrosion inhibitors for carbon steel in 1 M HCl solution. The corrosion inhibition efficiency was determined by weight loss measurement, potentiodynamic polarization, and electrochemical impedance spectroscopy. Results showed that such three inhibitors could effectively inhibit the corrosion of carbon steel in 1 M HCl solution, especially at their low concentrations, while the carbon chain length of Geminis used played a negligible role in the inhibition efficiency. Scanning electron microscopy/energy dispersive X-ray analysis observations demonstrated the formation of a protective inhibitor layer on the carbon steel surface. Additionally, the adsorption of the inhibitor molecules on the carbon steel surface was found to obey the Langmuir isotherm.