Long side-chain type partially cross-linked poly(vinylidene fluoride-co-hexafluoropropylene) anion exchange membranes for desalination via electrodialysis.

Surplus demand for freshwater gained considerable attention towards the development of desalination technologies, of those electrodialysis proved to be able to brackish water desalination. Herein, this article clearly explains the synthesis of poly(vinylidene fluoride-co-hexafluoropropylene) based anion exchange membranes (AEMs) for electrodialysis. Prepared series of AEMs is analyzed for stabilities and ion transport behavior to assess their suitability in electrodialysis. TEM and AFM imaging are used to get further insights about hydrophilic-hydrophobic phase separation and ionic domain clustering, which is critical for the amplification in electrochemical properties. Optimized membrane (AEM-1.0) exhibited notable electrochemical properties with water uptake of 44.3%, ion exchange capacity of 1.56 meq g−1, and ionic conductivity of 21.1 mS cm−1. Relatively high transport number (0.94) and limiting current density (43.7 A m−2) of AEM-1.0 membrane enables a broad window for faster electrodialytic desalination at a higher operating potential. Further, 1.05 kWh kg−1 energy consumption and 87.33% energy efficiency are realized for optimized AEM-1.0 membranes, which proves its efficiency to be employed in electrodialysis for brackish water desalination. Image 1 • Poly (vinylidene fluoride-co-hexafluoropropylene) based partially cross-linked AEMs. • Insights towards phase separation and ionic domain clustering are observed. • Melting temperature and crystallinity percent for AEMs reduced with 4-VP content. • High ionic conductivity at moderate water uptake and ion exchange capacity. • Low energy consumption and high energy efficiency in electrodialysis. [ABSTRACT FROM AUTHOR]