Amide-Linked Alkylpyridinium Gemini Surfactants for Corrosion Mitigation of Low-Carbon Steel

The anticorrosion properties of three amide-linked alkylpyridinium gemini surfactants (ALAPGS), viz., 3,3'-(propanediamide)bis(1-n-dodecylpyridinium) dibromide (ALDPGS), 3,3'-(propanediamide)bis(1-n-tetradecylpyridinium) dibromide (ALTPGS), and 3,3'-(propanediamide)bis(1-n-octadecylpyridinium) dibromide (ALOPGS), were studied on low-carbon steel in 3.5% NaCl through weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) methods. The anticorrosive efficiency of ALAPGS on low-carbon steel was contingent upon the concentration and length of the alkyl tails. In addition, the corrosion inhibition efficiency was found to be the highest when the concentration of the gemini reaches close to the critical micelle concentration (cmc) and followed the order ALOPGS > ALTPGS > ALDPGS. The results obtained from EIS agreed with the findings of PDP and weight loss experiments. The PDP studies indicated that the studied gemini acts as a mixed-type inhibitor. Furthermore, the morphology of low-carbon steel was studied through scanning electron microscopy and atomic force microscopy. Molecular dynamics simulations were conducted to understand the interaction between ALAPGS and low-carbon steel. The results suggested that ALAPGS are effective corrosion inhibitors for low-carbon steel.