Sulfonated polyethersulfone based cation exchange membranes for reverse electrodialysis under high salinity gradients

Salinity Gradient Power - Reverse Electrodialysis (SGP-RED) is a promising membrane-based technology to harvest the energy of mixing from solutions of different ionic concentration. Unfortunately, currently available commercial ion exchange membranes – being not specifically designed for RED – are f...

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Bibliographic Details
Published in:	Journal of membrane science Vol. 595; p. 117585
Main Authors:	Avci, Ahmet H., Rijnaarts, Timon, Fontananova, Enrica, Di Profio, Gianluca, Vankelecom, Ivo F.V., De Vos, Wiebe M., Curcio, Efrem
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-02-2020
Subjects:	Cation exchange membrane Electrochemical impedance spectroscopy Reverse electrodialysis Salinity gradient power Sulfonated polyethersulfone Salinity gradient power Sulfonated polyethersulfone Reverse electrodialysis Cation exchange membrane Electrochemical impedance spectroscopy
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Summary:	Salinity Gradient Power - Reverse Electrodialysis (SGP-RED) is a promising membrane-based technology to harvest the energy of mixing from solutions of different ionic concentration. Unfortunately, currently available commercial ion exchange membranes – being not specifically designed for RED – are far from satisfying the requirements of this operation, especially when operated with hyper-concentrated brines. In this work, novel sulfonated polyethersulfone (sPES) cation exchange membranes (CEM) were prepared by phase inversion method and tested under high salinity gradients. Use of 5 M NaCl electrolyte for immersion precipitation coagulation bath facilitated the self-standing membrane formation as a result of the electrostatic interaction between the fixed charged groups and electrolyte solution. Microscopy results revealed that dense or asymmetric membranes with non-connected pores were formed by solvent evaporation or immersion precipitation, respectively. The membranes were characterized for ion exchange capacity, water uptake, charge density and thickness, and further studied by electrochemical impedance spectroscopy. The obtained properties of the newly developed membranes were subsequently compared to those of commercial CMX (Neosepta, Japan) and Fuji-CEM-Type 1 (Fujifilm, The Netherlands) membranes. The asymmetric membranes resulted in a very low resistance especially for high ionic gradients but relatively low permselectivity, while dense membranes still had a low resistance compared to commercial membranes and exhibited high permselectivity. Interestingly, in terms of power density, lab-made membranes outperformed the commercial benchmarks when tested for RED applications with brackish water (0.1 M NaCl)/hypersaline brine (4 M NaCl) feeds; power density of CMX and Fuji-CEM-Type 1 were 3.23 and 3.77 W/m2, respectively, while power density of asymmetric and dense sPES membranes were 3.64 and 3.92 W/m2, respectively. [Display omitted] •Novel sulfonated polyethersulfone cation exchange membranes (CEMs) developed.•Immersion precipitation and solvent evaporation preparation techniques adopted.•Reverse Electrodialysis performance evaluated in terms of power density.•Benchmark commercial CEMs outperformed at high salinity gradients (0.1 M/4 M NaCl).
ISSN:	0376-7388 1873-3123
DOI:	10.1016/j.memsci.2019.117585