Carbon Dioxide Corrosion Inhibition of Carbon Steels Through Bis-imidazoline and Imidazoline Compounds Studied by EIS

The performance of (1-(2-hidroxyethyl)-2(heptadec-8-enyl)-imidazoline and 1-(2-aminoethyl)-2(heptadec-8-enyl)-bis-imidazoline has been studied by Electrochemical Impedance Spectroscopy (EIS) and Linear Polarization Resistance (LPR). A rotating cylinder electrode (RCE) was used for simulating turbulent conditions in a 3 wt. % NaCl solution saturated with CO2 at 80 °C, pH 4. EIS helped in the characterization of the inhibitor film at different concentrations and its respective evolution with time. It was found that 1-(2-aminoethyl)-2(heptadec-8-enyl)-bis-imidazoline formed a more compact inhibitor layer and therefore the corrosion protection was enhanced. The molecular structure of this inhibitor allows the usage of lower concentration (10 ppm) without loss of efficiency.