Studies on electrochemical behavior of copper in aerated NaBr solutions with Schiff base, N,N '-o-phenylen-bis(3-methoxysalicylidenimine)

The electrochemical behavior of copper in the aerated 0.5 mol dm(-3) sodium bromide solutions with or without a Schiff base, N,N'-o-phenylen-bis(3-met hoxysalicylidenimine) (V-o-Ph-V) were investigated by means of the steady-s tate 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 po tentials near the corrosion potential. The adsorbed V-o-Ph-V formed a thin protective film which reduced both anodic and cathodic reaction rates signi ficantly. The impedance spectra for copper measured at the corrosion potent ials in the presence of V-o-Ph-V displayed two capacitive loops due to diff erent influences of the protective film on the anodic and cathodic reaction s occurring at the copper surface. V-o-Ph-V could self-assemble on the copp er surface and the self-assembled film also exhibited a good inhibition on copper in halide solutions. The dissolution mechanism of copper and the inh ibition mechanism of V-o-Ph-V on the copper in NaBr solution are interprete d. In addition, the inhibiting action of V-o-Ph-V is compared with that of the other two Schiff bases, N,N'-o-phenylen-bis (3-methoxysalicylidenimine) (V-p-Ph-V) and N-[(2-hydroxy-3-methoxyphenyl)methylene]histidine (V-His) i n order to investigate the effect of Schiff bases' geometric structures on their inhibition ability. (C) 2001 The Electrochemical Society.