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

A reverse osmosis (RO) membrane with a high water permeance and salt rejection is needed to reduce the energy requirement for desalination and water treatment. However, improving water permeance while maintaining a high rejection of the polyamide RO membrane remains a great challenge. Herein, we report a rigid-flexible coupling strategy to prepare a high-performance RO membrane through introducing monoamine with a flexible aliphatic ring (i.e., piperidine (PPR)) into the interfacial polymerization (IP) system of trimesoyl chloride (TMC) and m-phenylenediamine (MPD). The resulted polyamide film consists of a robust aromatic skeleton and soft aliphatic-ring side chain, where the aliphatic ring optimizes the microstructure of polyamide network at a molecular level. The obtained membranes thereby showed an enhanced water permeance of up to 2.96 L center dot m(-2) h(-1) bar(-1), nearly a 3-fold enhancement compared to the control group, meanwhile exhibiting an ultrahigh rejection toward NaCl (99.4%), thus successfully overcoming the permeability-selectivity trade-off limit. Furthermore, the mechanism of the enhanced performance was investigated by molecular simulation. Our work provides a simple way to fabricate advanced RO membranes with outstanding performance.

Automated summary

We successfully prepared a high-performance reverse osmosis (RO) membrane using a rigid-flexible coupling strategy by introducing a flexible aliphatic ring monoamine (such as piperidine) into the interfacial polymerization system. The resulting polyamide film has a robust aromatic skeleton and a soft aliphatic-ring side chain, optimizing the microstructure of the polyamide network at a molecular level. The obtained membranes showed a significantly enhanced water permeance of up to 2.96 L·m-2·h-1·bar-1, nearly a 3-fold improvement compared to the control group, and an ultrahigh rejection towards NaCl (99.4%), overcoming the permeability-selectivity trade-off limit. Our work provides a simple approach to fabricate advanced RO membranes with outstanding performance.