Separation of Cations with Different Charges in Electrodialysis with the Use of Complex Formation

M. V. Rozhkova , V. A. Shaposhnik , I. P. Strygina , L. V. Artemova
Российский электрохимический журнал
Abstract / Full Text

The effect is studied of pH magnitude on the efficiency of separation of sodium and calcium ionsin the presence of disodium salt of ethylenediaminetetraacetic acid (EDTA), and the possibility is revealed ofthe separation of these ions at pH9, which is due to the fact that sodium ions are transferred predominantlythrough the cationite membrane while the CaY complex anions are transferred mainly through anionite membrane, under these conditions. Studying the effect of the current density on the separation of sodium and calcium ions shows that calcium ions transfer through the cationite membrane terminates at a current densityhigher than 12 mA cm–2. A study has been made of mass transfer of complex salt Na2CaY through ionite membranes from solutions of various concentration. It is shown that it is advantageous to process dilute chelate solutions under the conditions of flow electrodialysis, because the efficiency of processing a complex salt solutionfalls with an increase in its concentration. On examination of EDTA mass transfer through ion-exchange membranes during electrodialysis, a barrier effect is discovered, i.e. a decrease in the transport of EDTA anionsthrough the anionite membrane at a current density higher than the limiting one. This is caused by the amphoteric properties of EDTA.