Assessment of the electrochemical behaviour and inhibitive action of griseofulvin on copper in 1M NaOH solution

This study assesses the corrosion inhibition performance of griseofulvin, a pharmaceutical compound, on copper in 1 M NaOH solution at 30 °C, 40 °C, and 50 °C using electrochemical techniques. Varying concentrations (0.1–0.3 mL) of griseofulvin were tested. Potentiodynamic polarization and OCP measurements revealed that inhibition efficiency improved with concentration and exhibited temperature-sensitive behaviour. Tafel polarization results indicated that griseofulvin acts as a mixed-type inhibitor, affecting both anodic and cathodic reactions. The 0.3 mL concentration consistently provided the highest inhibition efficiencies, peaking at 78.85% at 50 °C with a corresponding corrosion rate reduction to 0.22 mm/yr. Optimization using Response Surface Methodology (RSM) and ANOVA validated the statistical significance of the influencing variables on inhibition efficiency. Adsorption behaviour followed the Langmuir model at 30 °C and the Freundlich model at elevated temperatures, confirming the inhibitor’s adsorption-driven mechanism. Thermodynamic analysis using ΔG⁰ads confirmed that the adsorption process was spontaneous and primarily governed by physisorption. Optical microscopy confirmed the surface protection of copper in the inhibited samples compared to the control. These findings highlight the innovative repurposing of a pharmaceutical waste product for corrosion control, aligning with the goals of green chemistry. Given its cost-effectiveness and stability at elevated temperatures, griseofulvin presents practical potential for industrial applications in alkaline systems.