Formation of complex compounds of univalent copper at the Cu0-Cu2+ interphase boundary in chloride solutions

Abstract

Kinetics and a mechanism of formation of compounds of univalent copper at the interphase boundary Cu0-Cu2+ in the solution containing excess chlorine anions are investigated by the spectrophotometry method. It is shown that the [CuCl2]− and [CuCl3]2− complex anions are formed during the contact of metal copper with the Cu2+ ions. The former ones are characterized by the appearance of the band in the region of 233 nm in the spectra of electron absorption, and the latters ones—in the region of 273 nm. The dependence of intensity of absorption bands on the contact time of the Cu2+ ions with copper is used to estimate the kinetic parameters of formation and oxidation of the [CuCl2]− and [CuCl3]2− ions. A thickness of the reaction layer, in which they are formed, is determined. The formation of the Cu(I) compounds during the contact interaction of copper with the Cu2+ ions is confirmed by the results of electrochemical investigations. The mechanism of cathode reduction of copper-containing compounds on a copper electrode is suggested.