In situ monitoring of corrosion inhibitor film formation and efficiency using simultaneous dynamic EIS and microbalance measurement

Understanding the dynamic adsorption behavior of corrosion inhibitors under real-time conditions is essential for advancing surface protection strategies. However, such insights are limited by conventional measurement techniques. In this paper, simultaneous quartz crystal microbalance (QCM) and dynamic electrochemical impedance spectroscopy (DEIS) measurements are evaluated as a novel approach for the direct observation of benzotriazole adsorption on nickel surface in hydrochloric acid. It was demonstrated that variations of electrochemical parameters- charge transfer resistance and constant-phase element admittance- correlate with the electrode mass changes. The findings showed that the adsorption of benzotriazole occurs within a few seconds after its addition to the solution, providing a rapid inhibitory effect. Furthermore, a procedure for extracting the adsorbate mass from the measured mass change was provided, allowing interpretation of QCM data obtained in a corrosive environment, where the mass of base metal continuously decreases. The estimated mass of benzotriazole adsorbed on Ni surface was approximately 0.3 μg cm-2 for 1 mM, 0.45 μg cm-2 for 5 mM, and 0.5 μg cm-2 for 10 mM. The results highlight the presented method as a valuable tool for the monitoring of corrosion inhibitor adsorption and performance.