Crown Ether-Based Covalent Organic Framework Packed Nanofiltration Membrane for Efficient Mg²⁺/Li⁺ Ion Sieving

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Developing highly selective ion separation membranes is crucial but challenging.
• Existing membranes often struggle with separating similar ions effectively.

Purpose of the Study:

• To report a novel covalent organic framework (ZUT-CEs-COF) utilizing crown ether units for enhanced ion separation.
• To investigate the performance of ZUT-CEs-COF as a nanofiller in nanofiltration membranes.

Main Methods:

• Synthesis of ZUT-CEs-COF with crown ether organic units.
• Fabrication of thin-film nanocomposite membranes incorporating ZUT-CEs-COF.
• Experimental evaluation of ion selectivity (Li+/Mg2+) and water flux.
• Density functional theory (DFT) calculations to understand ion-nanopore interactions.

Main Results:

• ZUT-CEs-COF exhibits high specific surface area, crystallinity, and stability.
• The modified membrane achieved a Li+/Mg2+ selectivity coefficient of 26.5 and a water flux of 52.4 L m⁻² h⁻¹.
• DFT calculations confirmed the role of nanopore binding energy in ion selectivity.

Conclusions:

• ZUT-CEs-COF is a promising material for creating highly selective ion separation membranes.
• The findings provide insights into designing membranes for efficient separation of similar ions.
• This work advances potential applications in selective ion separation technologies.