Green corrosion protection of copper in chloride media with Calystegia sepium extract using electrochemical and GC-MS/MS analyses

The use of sustainable and eco-friendly materials for corrosion inhibition has garnered significant attention in recent years. This study investigates the corrosion inhibition performance of Hedge Bindweed (Calystegia sepium) water extract as a green inhibitor for copper in a neutral saline medium containing 3.5 wt% NaCl. Electrochemical techniques, including potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), were employed to evaluate the inhibition behavior of the extract over a temperature range of 25-65 °C. The results revealed a maximum inhibition efficiency of 91.9% at an extract concentration of 5 × 10^{- 3} M. Weight loss measurements further confirmed the effectiveness of the inhibitor, yielding an inhibition efficiency of 90.4%. Notably, even at elevated temperatures, the extract maintained satisfactory performance, retaining approximately 50% inhibition efficiency at 65 °C, indicating reasonable thermal stability. Temperature-dependent linear sweep voltammetry (LSV) measurements provided insight into the thermodynamic and kinetic aspects of the corrosion process, showing an increase in activation energy in the presence of the inhibitor, consistent with a hindered corrosion reaction. Surface morphology and elemental composition analyses using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) confirmed the formation of a protective layer on the copper surface. Furthermore, gas chromatography-mass spectrometry (GC-MS/MS) analysis identified several bioactive compounds responsible for the inhibition effect. Thermodynamic adsorption studies demonstrated that the inhibitor adsorption followed the Langmuir isotherm, suggesting a predominantly physisorption-controlled mechanism. Overall, these findings highlight Hedge Bindweed extract as a highly efficient, sustainable, and eco-friendly corrosion inhibitor for copper in saline environments.