Transport of weak-electrolyte anions through anion exchange membranes: Current–voltage characteristics

Transport of salts of phosphoric and carbonic acids through anion exchange membranes (AEM) is studied by means of current–voltage responses. Concentration polarisation of such membrane systems is accompanied by a change in the electrolyte concentration at the membrane–solution interface due to hydrolysis reactions. Current–voltage characteristics (CVC) on HPO42− or PO43− ion-containing systems with modified AEM selectively permeable to mono-charged anions present two waves like in electrode multi-component systems with multi-stage electrochemical reactions. This phenomenon does not occur with nonmodified AEMs. It is also the case with all the AEMs studied for solutions containing HCO3−or CO32− salts because of close values of electrical resistances of the membranes in these both ionic forms.