Thermodynamic, electrochemical and surface characterization of copper corrosion inhibition in acidic solution using rice straw extract

The use of natural inhibitors offers a sustainable and cost-effective approach to mitigating copper corrosion. In this study, rice straw extract, an agricultural byproduct, was investigated as an eco-friendly corrosion inhibitor for copper in 0.5 M H₂SO₄ solutions. The corrosion inhibition performance was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques across a temperature range of 25-55 °C. The results demonstrated that the rice straw extract achieved an inhibition efficiency of approximately 91% at 25 °C with a concentration of 0.05 g/L and maintained a significant 69.1% efficiency at 55 °C, suggesting that the inhibition primarily occurs through physisorption of the extract molecules onto the copper surface. Scanning electron microscopy (SEM) analysis further confirmed the protective layer formation, while potential of zero charge (PZC) measurements indicated a negatively charged copper surface in sulfuric acid (- 13 mV). Adsorption isotherm studies revealed a strong binding constant, confirming that rice straw extract is an effective and sustainable corrosion inhibitor for copper in acidic environments.