Complexation of Polyelectroyte-Metal() Ion. . The Complex Formation of Iron(), Cobalt(), Nickel() and Copper() with Branched Poly(ethylene imine) (BPEI) in Aqueous Solution

摘要

The complex formation of branched poly(ethylene imine) (BPEI) with bivalent transition metal ions, such as Fe(￥±), Co(￥±), Ni(￥±) and Cu(￥±), have been investigated in terms of visible absorption and pH titration methods in an aqueous solution in 0.1M KCl at 30?é. The stability constants for M(￥±)-BPEI complexes was calculated with the modified Bjerrum method. The formation curves of M(￥±)-BPEI complexes showed that Fe(￥±), Co(￥±), Ni(￥±) and Cu(￥±) ions formed coordination compounds with four, two, two, and two ethylene imine group, respectively. In the case of Cu(￥±)-BPEI complex at pH 3.4 ?- 3.8, ￥?max was shifted to the red region with a decrease in the acidity. The overall stability constants (log K2) increased as the following order, Co(￥±) < Cu(￥±) < Ni(￥±) < Fe(￥±).