Green Chemistry Approach: <i>Eucalyptus globulus</i> Leaf Extract as an Eco‐Friendly Corrosion Inhibitor for Carbon Steel in Acidic Medium

Abstract The present study investigated the impact of the Eucalyptus globulus leaf extract on the dissolution rate of carbon steel samples (CS) in hydrochloric acid (HCl) medium. The extract's composition was determined by liquid chromatography‐mass spectrometry (LC‐MS) and Fourier transform infrared (FT‐IR) spectroscopy. The Eucalyptus globulus leaf extract (EGLE) was examined for its mechanism and effectiveness in corrosion mitigation using weight loss and electrochemical tests. The addition of 0.5 g/L EGLE at 25 ○ C, achieved a maximum corrosion inhibition efficiency of 97.39% in polarization measurements and 89.84% in weight loss measurements. The experimental results indicate that EGLE exhibits excellent anti‐corrosion properties in a 1 M HCl solution within a specific temperature range. Surface analysis by SEM and AFM revealed a significant reduction in CS surface degradation, indicating the formation of a protective film. The results demonstrate that EGLE is an effective mixed‐type corrosion inhibitor, following the Langmuir adsorption isotherm. Adsorption occurs via a mixed chemisorption‐physisorption mechanism. The protective hydrophobic adsorption film is effective in retarding the penetration of aggressive ions and inhibiting the corrosion of carbon steel in the hydrochloric medium. These findings highlight EGLE's potential as a sustainable, green corrosion inhibitor for industrial applications.