Effect of solution concentration and composition on the electrochemical properties of ion exchange membranes for energy conversion

By Fontananova, E.; Messana, D.; Tufa, R. A.; Nicotera, I.; Kosma, V.; Curcio, E.; Baak, W. van; Drioli, E.; Profio, G. Di
Published in Journal of Power Sources NULL 2017

Abstract

Abstract The electrochemical properties of ion exchange membranes (IEMs) applied for salinity-gradient power (SGP) harvesting, are usually measured using diluited NaCl aqueous solutions because of the prevalence of its constituents ions in natural solutions (e.g. seawater). However, in real applications, the {IEMs} come in contact with other ionic species than Na+ and Cl? that can have a relevant effect on their properties. As a consequence, the obtained results in many cases are not really representative. The aim of the present study was to investigate the effect of solution concentration and compositions on permselectivity, membrane and interface resistance, for both anion and cation exchange membranes (AEMs and CEMs). Special attention was paid to the influence of the most common multivalent ions in seawater (Mg2+, Ca2+ and SO42?) on the electrochemical properties of the {AEM} and the CEM. It was possible to discriminate the impact on the {AEM} from that on the CEM. The results highlighted a strong negative effect of Mg2+ on the {CEM} (relevant increase of ionic resistance and permselectivity) and, at minor extent, on the {AEM} (moderate reduction of permselectivity).

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