Preparation of Isoetes sinensis Extract as a Green Corrosion Inhibitor for Q235 Carbon Steel in Hydrochloric Acid

The corrosion inhibition performance of Isoetes sinensis extract on Q235 steel in 1 M HCl solution was investigated using polarization curves and electrochemical impedance spectroscopy. The results showed that Isoetes sinensis extract could significantly slow down the corrosion of carbon steel in hydrochloric acid solution. The corrosion inhibition rate reached 91% when the concentration of Isoetes sinensis was increased to 0.15 g/L. From the electrochemical analysis, it is clear that Isoetes sinensis extract mainly inhibits the cathodic corrosion reaction of carbon steel. The adsorption of corrosion inhibitor molecules in Isoetes sinensis extract on the carbon steel surface satisfies the Langmuir adsorption isotherm model, which is a non-homogeneous adsorption and there should be interaction forces between the adsorbed organic molecules.