The Effect of 2,2'-and 4,4'-Dipyridyl on the Electroreduction of Cu(Ⅱ) from Basic Solutions of Ethylene- diaminetetraacetic Acid (EDTA)

摘要

The results are presented of investigation of the effect of 2,2'- and 4,4'-dipyridyl on the potential-current characteristics of cathodic electroreduction of copper(Ⅱ) from basic solutions of EDTA. The applied heterocyclic bases exhibit very similar capabilities of sorption on metallic electrodes, whereas they differ significantly in their abilities to complex copper(Ⅱ) ions. It was found by the chronovoltammetric method that the addition of 2,2'-dipyridyl in the range of concentration from 5~*10~(-7) to 10~(-5) M substantially accelerates the cathodic reduction of copper. However, the presence of 4,4'-dipyridyl brought about a decrease of the reduction current peak within the concentration range, investigated i.e. 10~(-7) / 5~*10~(-4) M under the same experimental conditions. The different interaction of the ligands during the electroreduction of Cu-EDTA complexes was explained in terms of their different complexing properties. It was found that when the concentration of 2,2'-dipyridyl was comparable to the concentration of EDTA a new cathodic peak appeared on the polarization curves, due to the reduction of Cu(Ⅱ)-2,2' dipyridyl complex.