Novel Schiff base-based cationic Gemini surfactants as corrosion inhibitors for Q235 carbon steel and printed circuit boards

Surfactants play an essential role in the field of metal corrosion inhibition by adsorption. In this work, novel Schiff base-based cationic Gemini surfactants were synthesized, purified, and characterized, which particular chemical structures benefit to adsorbing on the metal surface and thus restricting metal corrosion. The corrosion inhibiting mechanism of the synthesized surfactants was researched by electrochemical impedance spectroscopy, potentiodynamic polarization, and weight loss measurements. It was found that the surfactants behave as mixed-type inhibitors, and the adsorption follows Langmuir isotherm. SG-16 presents the best anti-corrosion effect; its corrosion inhibition efficiency reaches 93.5% for Q235 carbon steel and 83.38% for printed circuit boards. Scanning electron microscopy and X-ray photoelectron spectroscopy were applied to investigate the sample's surface morphology, which showed that there were surfactants, oxide, and very few corrosion traces on the sample's surface. These experimental results show that the novel Gemini surfactants are efficient corrosion inhibitors for metal.