Polyamide membranes with nanoscale ordered structures for fast permeation and highly selective ion-ion separation

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Sustainable water treatment relies on membranes with high permeation and selective solute separation.
• Current membranes often face limitations in achieving both high flux and precise separation.

Purpose of the Study:

• To construct a novel nanofiltration membrane with enhanced water permeation and selective ion separation.
• To precisely control membrane microstructure using graphitic carbon nitride (g-C3N4) during interfacial polymerization.

Main Methods:

• Utilized graphitic carbon nitride (g-C3N4) nanosheets to control interfacial polymerization.
• Employed molecular dynamics simulations to understand piperazine diffusion.
• Applied computational fluid dynamics to elucidate transport mechanisms.

Main Results:

• Achieved a membrane with nanoscale ordered hollow structure, fast water permeance (105 L m⁻²·h⁻¹·bar⁻¹), and high Na2SO4 rejection (99.4%).
• Demonstrated precise Cl⁻/SO4²⁻ separation with a selectivity of 130.
• The g-C3N4 integration significantly restricted piperazine diffusion, leading to improved membrane structure.

Conclusions:

• The developed membrane surpasses state-of-the-art nanofiltration membranes in performance.
• This approach enables ultra-permeability and excellent selectivity for various water treatment applications, including ion separation, purification, desalination, and organics removal.