KINETICS OF COMBINED REDUCTION OF IONS OF HYDROGEN AND OXOANIONS IN CORROSION OF METALS IN OXIDIZING MEDIA

Investigations were carried into the kinetics of the combined reductio n of H2O2, CrO42-, BrO3- and hydroxonium ions on a copper cathode in a wide range of concentrations of the oxidizing agent and pH of solutio ns. The results show that after adding oxidizers to the acid solution the rate of precipitation of hydrogen on the copper cathode increases. The accelerating effect of the oxidizing agents on the reaction of di scharge of hydroxonium ions is strong in the media with pH < 2. The ma ximum increase of the rate of discharge of the hydrogen ions in the pr esence of oxidizers is detected at a potential varying from -0.65 to - 0.67 V (Tafel section of the polarization curve). The increase of the partial current of discharge of the hydroxonium ions (DELTAi(H-2) = i( H-2)-i(H-2)0) is larger than 40% of the increase of the total cathodic current. This indicates that not only slightly dissociated acids but also intermediate products of reduction of oxidizers can take place in the process of transfer to hydrogen ions to the surface of the electr ode.