Resistance of di-cationic surfactant containing pyridinium ions to metal oxidation in 1.0 M HCl medium

Abstract

In order to prevent metal corrosion in low-carbon steel, which is exposed to faster corrosion in acidic environments, a di-cationic surfactant containing two pyridinium ions with high anti-corrosion potential was synthesized in this study. The structural characterization of the new compound was carried out by spectroscopic techniques (FT-IR and NMR). As a result of corrosion tests performed with electrochemical techniques such as potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) for different inhibitor concentrations (2, 10 and 50 ppm) in 1.0 M HCl solution at 25 degrees C, it was found that the anti-corrosion effect increases with increasing inhibitor concentration. The adsorption of the surfactant to the metal surface has been proven by the contact angles measured for pure water dripping on the metal surface. From the equilibrium constant and Gibbs free adsorption energy calculated by Langmuir adsorption isotherm, it was determined that this di-cationic surfactant has a high adsorption ability and adheres to the surface by chemical adsorption. The chemical indices of conceptual density functional theory (DFT) were also examined to develop an understanding of how molecular/electronic factors can alter inhibition efficiency of inhibitor compound. In addition to this process, a Monte Carlo Simulation study was also performed. The corrosion protection of the metal was visually examined by scanning electron microscopy (SEM) analysis, the elemental percentage of the metal surface was revealed by electron dispersive X-ray spectroscopy (EDX) analysis and the average roughness of the surface was determined by atomic force microscopy (AFM) analysis.