Conducting polymers as ion-exchangers for water purification

Abstract

The charging and discharging processes of conducting polymers, e.g. polypyrrole, are accompanied by the exchange of ions. This effect was used for the development of an electrochemically switchable ion-exchanger for water purification, especially for softening drinking water. The ion-exchange behaviour and capacity of electrochemically and chemically prepared polypyrrole (PPy) in dependence on the incorporated counterions are characterised using an electrochemical quartz crystal microbalance and cyclovoltammetry. An ion-exchanger electrode based on modified PPy-nanoparticles was tested in a laboratory loop. The ion concentrations of the test solutions treated were investigated by atomic absorption spectroscopy and ion-selective electrodes with respect to an application for softening drinking water.