The elimination of small and potentially toxic boron species in water is always a significant challenge for conventional membrane technologies. In this study, facile intercalation and functionalization of β-cyclodextrin (CD) onto layered double hydroxides (LDHs) have resulted in the formation of accessible hydroxyl functional groups and anions that exhibit strong sorption and host–guest interaction with boron. Through meticulous molecular design and optimization, the modified LDH possessing the maximum boron adsorption capacity of 96.1 mg g−1 was employed to fabricate a polyamide-based thin-film nanocomposite (TFN) membrane with a loading of 0.10 wt%. This resultant membrane displayed a high salt rejection and water permeance of 99.4 % and 2.68 LMH bar−1 for brackish water, respectively, which can be attributed to the increased interlayer spacing of 1.67 nm and the thinner selective layer. The innovative TFN membrane also achieved a high boron rejection of 82.3 % against brackish water containing 2,000 mg L−1 NaCl and 15 mg L−1B at pH 8. This pioneering study provides valuable insights into the design of brackish water reverse osmosis (BWRO) membranes, through the synergistic use of macrocyclic molecules and inorganic layered nanomaterials, that could potentially revolutionize water reuse and boron removal applications.
Bibliographical noteKAUST Repository Item: Exported on 2023-09-05
Acknowledgements: The research is financially supported by the National Research Foundation, Singapore, and PUB, Singapore's National Water Agency under Urban Solution & Sustainability (Competitive Research Programme (Water) PUB-1901-0001) with the project entitled “Membrane Development with Enhanced Boron Removal Efficiency in Brackish Water Desalination (BWRO) for Post-Treatment of Seawater Desalination”. The authors thank the staff from NUS Chemical and Biomolecular Engineering, NUS Materials Science and Engineering, NUS Chemical, Molecular and Materials Analysis Centre (CMMAC), and NUS Environmental Research Institute for their assistance, and Dr. Guofei Sun from Aquaporin Asia Pte. Ltd. for the provision of PSf substrates. Prof. T.S. Chung would also like to thank the support from the Ministry of Science and Technology, Taiwan (Grant/Award No.: NSTC 110-2222-E-011-022-MY3) and the Yushan Scholar Program by Taiwan Ministry of Education. Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not reflect the views of National Research Foundation, Singapore and PUB, Singapore's National Water Agency.
ASJC Scopus subject areas
- Environmental Chemistry
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering