The Chemistry of ethylenediamine Tetra-Acetic acid in sea water

Abstract

A general formula has been derived for the quantitative treatment of systems involving a number of interdependent equilibria. The formula has been applied specifically to the equilibria set up between metallic cations and their chelates when EDTA is added to sea water. This system involves competition for the fully dissociated quadrivalent anion of EDTA (the principal ion of EDTA which forms complexes) by the metallic cations and by the hydrogenions present. The equilibrium concentration of a metallic cation in any particular case will depend upon the equilibrium concentration of the quadrivalent anion of EDTA, in the sense that the higher the concentration of this ion the lower will be the concentration of the metallic cation. The general formula allows the calculation of the equilibrium concentration of the quadrivalent EDTA anion, and from this the concentrations at equilibrium of each metallic cation can be readily found.