Anhydrous interfacial polymerization of sub-1 Å sieving polyamide membrane.

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Polyamide (PA) membranes are crucial for energy-efficient chemical separations due to their high permeability and ionic sieving capabilities.
• Achieving precise ionic sieving requires membranes with a narrow pore-size distribution, which is challenging to obtain through conventional methods.

Purpose of the Study:

• To develop an innovative membrane-forming process for creating highly permeable PA membranes with precise ionic sieving.
• To investigate the potential of anhydrous interfacial polymerization (AIP) for engineering PA membranes with controlled pore structures.

Main Methods:

• Anhydrous interfacial polymerization (AIP) was employed at a solid-liquid interface.
• A sublimated amine layer was reacted with alkane-containing acyl chlorides, eliminating water-induced side reactions.
• The process facilitated an intensive and orderly interfacial polymerization (IP) reaction.

Main Results:

• A unique PA layer was formed with an exceptional ionic sieving accuracy of 0.5 Å.
• The resulting AIP-PA membrane exhibited high separation selectivities for monovalent/divalent cations (e.g., Mg²⁺/Li⁺ at 78.3) and anions (e.g., Cl^-/SO₄^2- at 29.2).
• A high water flux of 13.6 L m^-2 h^-1 bar^-1 was achieved.

Conclusions:

• The anhydrous interfacial polymerization (AIP) strategy enables the fabrication of PA membranes with high precision and narrow pore-size distribution.
• This method offers a promising approach for engineering high-performance PA membranes for advanced separation applications.
• The AIP technique provides a pathway for developing energy-efficient separation processes.