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. (C) 2001 Elsevier Science B.V. All rights reserved.