Highly Permeable Nanofibrous Composite Nanofiltration Membranes by Controllable Interfacial Copolymerization

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Nanofibrous membranes are crucial for water purification.
• Developing membranes with high permeability and selectivity remains a challenge.
• Existing membranes often suffer from performance trade-offs.

Purpose of the Study:

• To develop an ultrathin nanofibrous composite nanofiltration (NF) membrane.
• To improve both permeability and rejection performance.
• To investigate the role of specific monomers in membrane fabrication.

Main Methods:

• Fabrication of a composite NF membrane via interfacial copolymerization on a sulfonated poly(ether sulfone) (SPES) nanofibrous substrate.
• Utilized 2,5-diaminobenzenesulfonic acid (2,5-DABSA) and piperazine (PIP) as aqueous monomers, and trimesoyl chloride (TMC) as the organic monomer.
• Employed molecular dynamics simulations to understand monomer diffusion and membrane structure.

Main Results:

• Developed an ultrathin polyamide barrier layer (∼56 nm) with enhanced electrostatic interactions.
• Achieved a permeation flux of 137.4 L/m²·h, four times higher than conventional NF membranes.
• Demonstrated excellent divalent salt (Na₂SO₄) rejection (99.4%) and improved fouling resistance against bovine serum albumin.
• Optimized monomer ratios (PIP:2,5-DABSA) to control cross-linking and pore size.

Conclusions:

• The developed composite NF membrane effectively breaks the permeability-selectivity trade-off.
• The incorporation of 2,5-DABSA significantly enhances negative charge, improving sulfate rejection and fouling resistance.
• The membrane shows great potential for efficient and robust water treatment applications.