Acteoside: a novel green inhibitor for the corrosion of copper in 1.0 M HNO₃ solution: experimental and theoretical investigation

Acteoside (ACT) isolated from <i>A. orientalis</i> L. was investigated as a corrosion inhibitor of copper in 1.0 M HNO₃ acid solutions using conventional weight loss, electrochemical polarization, and electrochemical impedance spectroscopy (EIS) studies. The molecular structure of acteoside (ACT) is supported by all the experimental results from LC-MS, FT-IR, ¹H, and ¹³C-NMR. The findings indicate that ACT is a potent inhibitor, and that its effectiveness increases with both temperature and inhibitor concentration. The highest inhibitor concentration occurs at 48 °C, and the inhibition efficiency peaks at 98.8%. The results indicated that the presence of the inhibitor slightly lessened copper dissolution with rising temperature. ACT adheres to the Langmuir, Freundlich, El-Awady, Temkim, and Redlich-Peterson (R-P) adsorption isotherms on copper surfaces with a high regression coefficient value. The values of the activation parameters (<i>E</i> _a, Δ<i>H</i>*, Δ<i>S</i>*) and the adsorption thermodynamic functions (Δ<i>G</i> _ads) suggest both physisorption and chemisorption processes. Electrochemical polarization data were used to identify the mixed mode of inhibition. Active molecules adhere to the metal surface and form a protective layer, which causes changes in impedance characteristics, charge transfer resistance, and double layer capacitance in response to variations in ACT concentration. Weight loss and electrochemical data are supported by quantum chemical computations.