SOLUTION SPECIATION IN THE AQUEOUS NA(I)-EDTA AND K(I)-EDTA SYSTEMS

Speciation in the aqueous sodium(I) - ethylenediaminetetraacetic acid and potassium(I) - ethylenediaminetetraacetic acid equilibrium systems was investigated by automated gravimetric potentiometric titration. I t was found that in both cases, particularly below neutral pH values, speciation includes a previously uncharacterized diprotonated complex. All formation and acid dissociation constants were measured for the f ull systems. The validity of previous literature equilibrium constants , which are based on incomplete equilibrium models, is discussed.