Ion Exchange Equilibria of Metal Chelates of Ethylenediaminetetraacetic Acid (EDTA) with Amberlite IRA-68

The exchange equilibria of metal chelates of EDTA (ethylenediaminetetraacetic acid) from an equimolar solution of metals and EDTA with a weak-base ion exchanger Amberlite IRA-68 were studied. Experiments were carried out as a function of aqueous pH, the metal concentrations, and temperature. It was shown that whether the aqueous phase was initially acidic or basic, it became acidic and more acidic after exchange. The measured equilibrium isotherms could be well-correlated by the Langmuir equation on a macroscopic basis. The effect of temperature on the equilibria of ion-exchange reactions was studied, and also the corresponding thermodynamic data were evaluated.