Use of Phalaris canariensis Extract as CO₂ Corrosion Inhibitor of Brass

The corrosion inhibition action of Phalaris canariensis extract on brass in a CO2-saturated 3.5% NaCl solution has been evaluated with the aid of potentiodynamic polarization curves, linear polarization resistance and electrochemical impedance spectroscopy tests. Results have indicated that 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 for more than two orders of magnitude. The addition of the Phalaris canariensis extract increased the pitting potential and 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 elapsing time. Main compounds found in the Phalaris canariensis extract included antioxidants such as palmitic and oleic acids.