Dual-layer Janus charged nanofiltration membranes constructed by sequential electrospray polymerization for efficient...

Area of Science:

• Materials Science
• Environmental Engineering
• Chemical Engineering

Background:

• Water softening is crucial for improving water quality but remains technically challenging.
• Conventional nanofiltration (NF) membranes with single-charged layers show limited capacity for hardness ion removal.
• Developing efficient and cost-effective water softening technologies is essential.

Purpose of the Study:

• To develop novel dual-layer Janus charged NF membranes for enhanced water softening.
• To investigate the impact of the barrier layer's microstructure on ion separation performance.
• To understand the mechanisms behind the improved performance of Janus charged membranes.

Main Methods:

• Sequential electrospray polymerization was used to fabricate dual-layer Janus charged polyamide NF membranes.
• The microstructure of the dually charged barrier layer was systematically studied.
• Separation performance for divalent salt ions and antifouling properties were evaluated.

Main Results:

• The Janus charged NF membrane with a loose outer layer achieved 93.6% hardness removal, outperforming singly charged membranes.
• The microstructure of the outer layer was found to be critical in controlling ion separation by preventing reverse ion transport.
• The developed membrane demonstrated excellent antifouling properties, attributed to its negatively charged outer layer.

Conclusions:

• Dual-layer Janus charged NF membranes offer superior water softening capabilities compared to conventional membranes.
• Microstructural design of the barrier layer is key to optimizing ion separation and preventing reverse ion transport.
• These findings provide valuable insights for developing next-generation high-efficiency water softening NF membranes.