White Willow Bark Extract as a Copper Corrosion Inhibitor

This study investigates white willow bark extract (WWBE) as a potential corrosion inhibitor for Cu-DHP in a 0.5 M NaCl solution, using a non-destructive electrochemical methods, namely electrochemical frequency modulation (EFM), and electrochemical impedance spectroscopy (EIS).Electrolytes consisted of 0.5 M NaCl solutions both with and without the addition of WWBE (0.1-0.5 g l -1 ).The 0.5 M NaCl solution containing 0.5 g l -1 WWBE, both in the presence and absence of a copper plate, was analysed by ultraviolet-visible spectroscopy (UV-Vis).The experiments were conducted at room temperature.The EFM results indicated that WWBE functioned as a cathodic copper corrosion inhibitor, with the highest inhibition efficiency observed for the 0.5 M NaCl solution containing 0.5 g l -1 WWBE.The EIS results suggested the formation of a protective WWBE inhibitor film.The corrosion process was diffusion-controlled, both with and without the addition of WWBE.Both electrochemical methods demonstrated that WWBE adsorbed onto the copper surface in 0.5 M NaCl solution via physisorption, following the Langmuir adsorption isotherm.The Gibbs free energy values of adsorption were similar for EFM and EIS.The UV-Vis results showed that immersion of copper in an electrolyte containing 0.5 g l -1 WWBE for 24 h led to a change in the absorbance maximum, indicating the formation of a copper-WWBE complex.Overall, the results indicate that WWBE is an effective inhibitor of copper corrosion in chloride conditions.Further research will focus on the identification of compounds and organometallic complexes in WWBE and their individual effects on the corrosion process.