COPPER DISSOLUTION AND HYDROGEN-PEROXIDE FORMATION IN AQUEOUS-MEDIA

Dissolution of copper in aerated water or in neutral aqueous solutions is a slow but measurable process. Sensitive analytical techniques have been developed to quantify this process. The rate of dissolution in aerated deionized water at 20-degrees-C is (0.7 +/- 0.1) nm/h. Hydrogen peroxide is a by-product of this process. Measurements of the interaction between copper and aqueous media as a function of time, temperature, surface-to-volume ratio, and solute content indicate that, in general, the rates of formation of H2O2 in neutral solutions follow the same trends as those of the formation of Cu ions. Furthermore, the solute studies show that water-derived radicals (H, OH, e-(aq)) do not function as intermediates during the interaction of Cu with water and that the reaction leading to H2O2 formation probably proceeds through steps involving oxygenated Cu species at the metal-solution interface.