Kinetics of the metal exchange reaction of a Cu(II)-poly(vinyl alcohol) complex with Zn(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid in aqueous solution

The kinetics of the metal exchange reaction between Cu(II)-poly(vinyl alcohol) [Cu(II)-PVA] and Zn(II)-ethylenediamine-N,N,N′,N′-tetraacetic acid [Zn(II)-EDTA] has been studied by mixing both solutions in a spectrophotometer at pH 10.0 to 11.0, ionic strength μ=0.10(KNO3), and 15 to 35°C. The reaction is initiated by the formation of unstable Cu(II)-H-PVA through attack of H+ ion on the Cu(II)-PVA complex, and both reactions, ligand exchange and metal exchange, proceed simultaneously. The metal exchange step may be rate determining. The rate equation and rate constants of this reaction were determined as follows: −d[Cu(II)-PVA]/dt=k0(H)[PVA−][Cu(II)-PVA] [Zn(II)-EDTA], wherek0(H)=k1+(k′2+k′3)[H+],k1=5.98±1.64M−1 s−1, andk2+k3=k′2K Cu(II)-H-PVA −H +k′3K Zn(II)-EDTA H =(5.91±0.89)×107M−2 s−1.