Studies on Electrochemical Behavior of Copper in Aerated NaBr Solutions with Schiff Base, N , N ′ ­ o-phenylen-bis(3-methoxysalicylidenimine)

Abstract

The electrochemical behavior of copper in the aerated 0.5 mol dm−3 sodium bromide solutions with or without a Schiff base, -phenylen-bis(3-methoxysalicylidenimine) (V-o-Ph-V) were investigated by means of the steady-state polarization and impedance techniques. V-o-Ph-V acted as a mixed-type inhibitor in NaBr media, and it adsorbed easily on the copper surface at potentials near the corrosion potential. The adsorbed V-o-Ph-V formed a thin protective film which reduced both anodic and cathodic reaction rates significantly. The impedance spectra for copper measured at the corrosion potentials in the presence of V-o-Ph-V displayed two capacitive loops due to different influences of the protective film on the anodic and cathodic reactions occurring at the copper surface. V-o-Ph-V could self-assemble on the copper surface and the self-assembled film also exhibited a good inhibition on copper in halide solutions. The dissolution mechanism of copper and the inhibition mechanism of V-o-Ph-V on the copper in NaBr solution are interpreted. In addition, the inhibiting action of V-o-Ph-V is compared with that of the other two Schiff bases, -phenylen-bis (3-methoxysalicylidenimine) (V-p-Ph-V) and N-[(2-hydroxy-3-methoxyphenyl)methylene]-histidine (V-His) in order to investigate the effect of Schiff bases’ geometric structures on their inhibition ability. © 2001 The Electrochemical Society. All rights reserved.