High-Performance Polyamide Reverse Osmosis Membrane Containing Flexible Aliphatic Ring for Water Purification

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• High water permeance and salt rejection are crucial for energy-efficient desalination and water treatment.
• Improving water permeance in polyamide reverse osmosis (RO) membranes without compromising salt rejection is a significant challenge.

Purpose of the Study:

• To develop a high-performance RO membrane by introducing a flexible aliphatic ring into the interfacial polymerization system.
• To overcome the permeability-selectivity trade-off in RO membranes.

Main Methods:

• Utilized a rigid-flexible coupling strategy involving interfacial polymerization (IP) of trimesoyl chloride (TMC) and m-phenylenediamine (MPD).
• Introduced monoamine with a flexible aliphatic ring, piperidine (PPR), into the IP system.
• Characterized the resulting polyamide film's microstructure and membrane performance.

Main Results:

• The modified polyamide film featured a robust aromatic skeleton and a soft aliphatic-ring side chain, optimizing network microstructure.
• Achieved enhanced water permeance up to 2.96 L·m⁻² h⁻¹ bar⁻¹, a nearly 3-fold increase compared to the control.
• Demonstrated ultrahigh NaCl rejection of 99.4%, surpassing the permeability-selectivity trade-off limit.

Conclusions:

• The rigid-flexible coupling strategy effectively enhances RO membrane performance.
• Piperidine incorporation optimizes polyamide network structure, leading to superior water permeance and salt rejection.
• This approach offers a simple method for fabricating advanced RO membranes for water treatment applications.