Electrochemical Investigation on Corrosion Inhibition of an Imidazoline Derivative on CO2 Corrosion of Carbon Steel and Study the Effect of Iodide Ions on its Performance

The corrosion inhibition of plain carbon steel was studied by using an imidazoline derivative as an inhibitor and iodide ions additive in CO2-saturated 3% NaCl solution with potentiodynamic technique in Tafel region. The experimental results revealed that the imidazoline derivative inhibited the corrosion of steel and the extent of its inhibition was concentration dependent. The results of potentiodynamic polarization investigations revealed that imidazoline functioning as a mixed inhibitor showing anodic and cathodic behavior. Also, it was resulted that the inhibition efficiency of imidazoline was enhanced by addition of iodide ions due to synergistic effect and the synergism parameter was found to be greater than unity. Furthermore, the adsorption of imidazoline derivative on the steel surface followed the Langmuir adsorption isotherm and it was chemically adsorbed on the surface of the steel. The surface morphology was investigated by a scanning electron microscope and the result showed the formation of a protective surface film. Also it was found that surface roughness decreased after addition of inhibitor and iodide ions.