Ricinodendron heudelotii Almond Extract as a Novel Green Corrosion Inhibitor for XC70 Steel in Acidic Medium

Abstract In recent years, there has been growing interest in the use of safe, non‐polluting substances, due to increased environmental awareness and stricter environmental protection regulations. This development has led to the emergence of a new class of corrosion inhibitors, known as green corrosion inhibitors. The present study aims to evaluate the inhibitory effect of different concentrations of Ricinodendron heudelotii (RHA) almond extract on the corrosion of XC70 mild steel in a 0.5 M hydrochloric acid (HCl) solution. The evaluation was performed using weight loss measurements, electrochemical techniques, and surface characterization methods. Potentiodynamic polarization tests revealed that RHA functions as a mixed‐type inhibitor. Electrochemical impedance spectroscopy (EIS) tests showed that increasing the extract concentration leads to higher charge transfer resistance and lower double‐layer capacitance. The adsorption of the inhibitor onto the steel surface followed the Langmuir isotherm model, and surface characterization confirmed the formation of a protective RHA layer. The results demonstrate that RHA is an effective corrosion inhibitor, achieving a maximum inhibition efficiency of 92% at a concentration of 1.2 g/L.