Inhibitive action of the purine and adenine for copper corrosion in sulphate solutions

The influence of the concentration of the purine (PU) and adenine (AD) on the corrosion of copper in 0.5 M Na2SO4 solutions (pH 6.8) was studied. The investigations involved electrochemical polarization methods as well as electrochemical quartz crystal microbalance (EQCM) techniques. The inhibition efficiency increases with an increase in the concentration of PU and AD. Adherent layers of inhibitors were postulated to account for the protective effect. The adsorptions of inhibitors were found to occur on the surface of copper according to the Langmuir isotherm. The values of standard free energies of adsorption suggest the chemical adsorption of PU and AD on the copper surface.