Inhibition Mechanism of Imidazoline Derivatives Inhibitor for L360 Steel in Saltwater Saturated with CO_2

摘要

2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethyl]-methylamine (HDM), 2-(2-Henicos-10-enyl-4,5-dihydro-imidazol-1-yl)-ethanol (HDE) and 2-Henicos-10-enyl-4,5-dihydro-1H-imidazole (HDI) were synthesized and characterized by FT-IR. The corrosion inhibition properties of these compounds on mild steel L360 in 3.5% NaCl was investigated by weight loss, potentiodynamic polarization, electrochemical impedance and scanning electron microscopic techniques. Result of the study showed that the inhibition efficiency increased with increase in the concentration of the inhibitor to a maximum and decreased with further rise in temperature. An adherent layer of inhibitor molecules on the surface is proposed to account for their inhibitive action in which the organic molecules adsorb on the active anodic and cathodic sites following Langmuir isotherm. The effectiveness of these inhibitors has been correlated to their chemical structures and were in the order of HDM > HDE > HDI. The values of activation energy, free energy of adsorption and heat of adsorption were also calculated to elaborate the mechanism of corrosion inhibition. The potentiodynamic polarization data show that the compounds studied are mixed type inhibitors. Electrochemical impedance was used to investigate the mechanism of corrosion inhibition. The surface characteristics of inhibited and uninhibited metal samples were investigated by scanning electron microscopy (SEM).