Kinetics of metal exchange reaction of Cu(II)‐poly(vinyl alcohol) complex with Ca(II)‐ethylenediamine‐N,N,N′,N′‐tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between the Cu(II)‐poly(vinyl alcohol) complex (Cu(II)‐PVA) and Ca(II)‐ethylenediamine‐N,N,N′,N′‐tetraacetic acid (Ca(II)‐EDTA) were studied by mixing both solutions in a spectrophotometer at pH 9.7–11.0, at μ = 0.10(KNO 3 ) and at 25°C. The reaction is initiated by the formation of unstable Cu(II)‐H‐PVA by the attack of H + to Cu(II)‐PVA, and while both ligand exchange and metal exchange steps occur, the latter may be rate‐determining. The kinetic expression of this reaction was determined as ‐d[Cu(II)‐PVA]/dt = k[Cu(II)‐PVA] [H + ] [PVA]/[Ca(II)‐EDTA], where k = k 1 + k′ 2 [H + ], k 1 = 3.85 × 10 −2 sec −1 , k 2 = k′ 2 · K −H Cu(II)‐H‐PVA 9.59 × 10 5 1 mol −1 sec −1 .