Absorption spectra and composition of complexes sorbed in ion exchangers—I The copper(II)-chloride complex system

Abstract

The absorption spectra of copper(II)-chloride complexes adsorbed on anion-exchange resins of various degrees of crosslinking from a solution in 6 M hydrochloric acid and different copper concentrations have been observed. The composition of those complexes giving particular spectral patterns in the resin phase has been investigated by ion-exchange distribution measurements. At low copper concentrations or low degrees of crosslinking of the resin, a monomeric chlorocomplex (CuCl 3 −) was predominant. A binuclear complex (Cu 2Cl 7 3−) with a chloride ion bridge was gradually produced at higher concentrations of copper or higher degrees of crosslinking of the resin. Thus the following equilibrium may occur in the resin phase. 2 CuCl 3 − + Cl − ⇌ Cu 2Cl 7 3−. The validity of ion-exchange methods employed in this work was confirmed by experiments with chlorocomplexes of iron(III) and cobalt(II) whose compositions in the resin phase are known.