Frabication of an eco-friendly corrosion inhibitor from Terminalia catappa leaf concrete reinforcement in seawater

Metal corrosion is one of the most challenging problems facing industries. Using corrosion inhibitors is one reasonable approach to protecting metal surfaces. Due to the toxicity of industrial corrosion inhibitors, researchers are continuously searching for green, economical, and friendly alternatives. The present study focuses on the application of Terminalia catappa leaf extract to mitigate the corrosion of concrete reinforcing steel in a simulated seawater environment. The dry product from the Terminalia catappa leaf extraction process was determined to have amino functional groups in polyphenols. Polarization results demonstrate that the corrosion current density decreases from 8.87 A/cm2 (for samples soaked in blank solution) to 5.12 µA/cm2 when adding the optimal concentration of 0.004% of Terminalia catappa leaf extract. 3.5% NaCl solution. Electrochemical impedance spectroscopy (EIS) analysis showed that the inhibition efficiency reached over 90% at this concentration after 24 hours of soaking.