Adsorption-Desorption Kinetics of Benzotriazole on Cathodically Polarized Copper

We describe a facile and simple electrochemical method to study the durability and adsorption-desorption kinetics of benzotriazole (BTAH) on cathodically polarized copper. The adsorption and the protective film formation are time-dependent processes. In solutions containing a very low concentration of BTAH (similar to 10(-4) M), the results suggested that protection is attributed to a reversible physisorption process. The rate and extent of adsorption increased as a function of BTAH concentration in the electrolyte. The adsorbed BTAH desorbed entirely from the copper surface upon the removal of BTAH from the electrolyte. However, at higher BTAH concentrations (>= 10(-3) M), the process involves the formation of a film that remained stable and acted as a protective substrate even after the removal of BTAH from the electrolyte, i.e., the irreversible process.