Membrane capacitive deionization (MCDI) is a promising technique to achieve desalination of low-salinity water resources. The primary requirements for developing and designing materials for MCDI applications are large surface area, high wettability to water, high conductivity, and efficient ion-transport pathways. Herein, we synthesized ionic covalent organic nanosheets (iCONs) containing guanidinium units that carry a positive charge. A series of quaternized polybenzimidazole (QPBI)/iCON (iCON@QPBI) nanocomposite membranes was fabricated using solution casting. The surface, thermal, wettability, and electrochemical properties of the iCON@QPBI nanocomposite membranes were evaluated. The iCON@QPBI anion-exchange membranes achieved a salt adsorption capacity as high as 15.6 mg g−1 and charge efficiency of up to 90%, which are 50% and 20% higher than those of the pristine QPBI membrane, respectively. The performance improvement was attributed to the increased ion-exchange capacity (2.4 mmol g−1), reduced area resistance (5.4 Ω cm2), and enhanced hydrophilicity (water uptake = 32%) of the iCON@QPBI nanocomposite membranes. This was due to the additional quaternary ammonium groups and conductive ion transport networks donated by the iCON materials. The excellent desalination performance of the iCON@polymer nanocomposite membranes demonstrated their potential for use in MCDI applications and alternative electromembrane processes.
Bibliographical noteKAUST Repository Item: Exported on 2022-05-10
Acknowledgements: The authors would like to thank Jordan Gaskell (University of Manchester) for performing TGA of membrane samples. The authors would also like to thank Athanasios Papaderakis (University of Manchester) for assisting with the EIS measurements. SK thanks the postdoctoral fellowship from the King Abdullah University of Science and Technology (KAUST). The authors acknowledge the UK's Engineering and Physical Sciences Research Council (EPSRC) under grant code EP/L01548X/1 for funding Robert McNair's doctoral studies through the University of Manchester's Graphene NOWNANO CDT account. Further equipment funding via EPSRC grants EP/S019367/1 and EP/P025021/1 to the Royce Institute are also gratefully acknowledged. The research reported in this publication was supported by funding from KAUST.
ASJC Scopus subject areas
- Water Science and Technology
- Materials Science(all)
- Chemical Engineering(all)
- Mechanical Engineering