Corrosion protection of 1018 carbon steel using an avocado oil-based inhibitor

The corrosion phenomenon in oil and gas industry is a serious issue affecting metallic structures and pipelines. The main aggressive species flowing through oil pipelines is NaCl. The presence of gases in the corrosive medium (CO₂ and H₂S), increases, even more, its aggressiveness. Usually, to mitigate corrosion, liquid inhibitors are added to the corrosive medium. In the present study, N-hydroxyethyl-imidazoline derivatives of avocado oil was synthesized as a green corrosion inhibitor. The test was performed on 1018 carbon steel at 5, 10, 25, 50 and 100 ppm. Electrochemical techniques as polarization curves (PC), the open circuit potential (OCP), the lineal polarization resistance (LPR) and the electrochemical impedance spectroscopy (EIS) were applied. The results obtained from the OCP indicates that the inhibitor can be classified as a cathodic type one. On the one hand, PC, RPL and EIS determined that the highest corrosion rate was obtained without the inhibitor. On the other hand, by adding inhibitor, the corrosion resistance increased, obtaining the optimal concentration at 10 ppm. The EIS technique in the angle phase format showed the formation of two time constants, which indicates the inhibitor presence. Finally, the SEM analyses showed a minor attack at 5 and 10 ppm.