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

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...

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Bibliographic Details
Published in:Journal of power sources 2017-02, Vol.340, p.282-293
Main Authors: Fontananova, E., Messana, D., Tufa, R.A., Nicotera, I., Kosma, V., Curcio, E., van Baak, W., Drioli, E., Di Profio, G.
Format: Article
Language:English
Subjects:
Impedance spectroscopy
Ion exchange membranes
Ionic strength
Multivalent ions
Reverse electrodialysis
Salinity-gradient power
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Summary: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). [Display omitted] •Solution ionic strength and composition influence the properties of IEMs.•Increasing solution ionic strength the membrane water uptake decreases.•Mg2+ has a strong negative impact on CEM resistance and permselectivity.•A new parameter, called EME, is proposed to predict IEMs performance.
ISSN:0378-7753
1873-2755
DOI:10.1016/j.jpowsour.2016.11.075