An electrochemical and sers study of the action of polyvinylpyrrolidone and polyethylenimine as inhibitors for copper in aerated H2SO4

The adsorption and inhibitive effects of polyvinylpyrrolidone (PVP) and polyethylenimine (PEI) on copper in 2 M H2SO4 at 30 degrees C have been investigated by means of weight loss, potentiodynamic and in situ surface-enhanced Raman scattering (SERS) techniques. Both polymers reduce the rate of the anodic (metal dissolution) and cathodic (O-2 reduction) corrosion reactions. At all concentrations studied, PVP was found to be the better inhibitor. The dependence of the adsorbate spectra on applied potential and pH was established. There was evidence for PVP adsorption through oxygen whilst PEI showed coordination through the nitrogen atom.