Synthesis of 2-methylpyridinium Based Surfactants for Corrosion Mitigation of CR4 Mild Steel in Acidic/Chloride Media

Abstract

Corrosion, a ubiquitous phenomenon, causes significant economic loss that jeopardizes the integrity of the material (usually metals) and results in economic loss. To combat the damaging effects of corrosion, surfactants exhibit remarkable potential in forming a protective coating to prevent corrosion from the metal surface. This research focuses on the synthesis of 2-methylpyridinium based surfactants namely N-octyl-2-methylpyridinium bromide (MP8), N-decyl-2-methylpyridinium bromide (MPIO), and N-dodecyl methylpyridinium bromide (MP12). The synthesized compounds were characterized using FT -lR and NMR studies. Conductometry was used to study the micellization process of the cationic surfactants. The solvent selected to study micellization was water throughout the study. The hydrophobic tail length is inversely related to the CMC. The synthesized compounds were tested for corrosion in 3.5% NaCl solution at pH 1.5. The weight loss data combined with electrochemical studies i.e., Tafel polarization and electron impedance spectroscopy (ElS) were used to evaluate the mode of inhibition and degree of surface coverage by the inhibitors. The incorporation oflonger alkyl chain imparts a positive effect on the inhibition efficiencies. According to potentiodynamic polarization the surfactants behave as mixed type and maximum inhibition efficiency was recorded for MP12. The data obtained from EIS provide good agreement with the results obtained from weight loss and Tafel polarization. The maximum inhibition efficiency recorded was 98% for MP12. The surface morphology and formation of the protective film were confirmed by the scanning electron microscope (SEM) and energy dispersive X-rays (EDX) analysis. The experimental studies confirm that the synthesized surfactants have good corrosion inhibition efficiency.