Synthesis of gemini cationic surfactants-based pyridine Schiff base for steel corrosion and sulfate reducing bacteria mitigation

Three gemini cationic surfactant with different hydrophobic tails labeled GSBO, GSBD, and GSBH based azomethine and pyridine nuclei have been synthesized and confirmed spectroscopy via FTIR, ¹HNMR, and mass spectroscopy. The surface and thermodynamic study were conducted via measurement the surface tension measurements at different temperatures for well examining their corrosion inhibition efficiency. The affinity of the GSBO, GSBD, and GSBH toward micelle formation and adsorption at interface were hydrophobic and temperature dependent. The C-steel corrosion suppression via the synthesized GSBO, GSBD, and GSBH in 1 M H₂SO₄ were evaluated using electrochemical impedance spectroscopy, weight loss and polarization techniques, demonstrating their efficient affinity to mitigate the steel corrosion. Increasing the surfactant hydrophobicity exhibit higher ability to suppress the corrosion, as confined by the higher inhibition efficiency achieved by GSBH of 94.5 % that matched with higher adsorption affinity as claimed from the surface and thermodynamic investigation. The Tafel examination clarified GSBO, GSBD, and GSBH behaves as mixed type inhibitors following modified Langmuir isotherm. The inhibitors adsorption on C-steel was confirmed by XPS and SEM surface examination. Ultimately the synthesized azomethine based pyridine nuclei showed affinity to mitigate the sulfate reducing bacteria (SRB) with cut-off point observed for GSBO.