Ionic Strength Dependence of Dioxovanadium(V) Complexation with Ethylene Glycol-bis(2-aminoethylether)-N,N,N ',N '-tetraacetic Acid

Stability constants for the complexation processes of the VO(2)(+) ion with ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) in sodium perchlorate aqueous solutions for ionic strengths between (0.10 and 1.00) mol.dm(-3) were calculated at T=298 K by potentiometric and UV spectroscopic methods. The results indicate that EGTA forms the VO(2)H(3)L, VO(2)H(2)L(-), and VO(2)HL(2-) species with the VO(2)(+) ion in the pH range of about 1.00 to 2.50. Different thermodynamic models (extended Debye-Huckel type (EDH), specific ion interaction theory (SIT), and parabolic) have been examined for the ionic strength dependence of the stability and dissociation constants for the above-mentioned species.