Use of Phalaris canariensis Extract as CO₂ Corrosion Inhibitor of Brass

In this study, the corrosion inhibition of a Phalaris canariensis extract on brass in a CO₂-saturated 3.5% NaCl solution is evaluated with the aid of potentiodynamic polarization curves and electrochemical impedance spectroscopy tests. The results indicate that the Phalaris canariensis extract is an excellent CO₂ corrosion inhibitor with an efficiency that increases with its concentration, reaching its maximum value of 99% with an inhibitor concentration of 100 ppm, decreasing the corrosion current density by more than two orders of magnitude. The addition of the Phalaris canariensis extract increased the pitting potential, decreased the passive current density values, and affected cathodic reactions, behaving as a mixed type of inhibitor. The corrosion process was under charge transfer control, and it was neither affected by the addition of the inhibitor nor by the elapsing time. The main compounds found in the Phalaris canariensis extract included antioxidants such as palmitic and oleic acids.