COF-based membranes for liquid phase separation: Preparation, mechanism and perspective

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Covalent organic frameworks (COFs) are crystalline porous materials with tunable properties.
• COFs are increasingly utilized in membrane separation technologies due to their low density, high surface area, and modifiable pore structures.

Purpose of the Study:

• To review and compare various preparation methods for COF membranes.
• To explore the application potential of COF membranes in diverse liquid separation processes.
• To elucidate the mechanisms governing COF membrane separation performance.

Main Methods:

• Summarized conventional COF membrane preparation techniques: two-phase interfacial polymerization, in-situ growth, unidirectional diffusion, layer-by-layer assembly, and mixed matrix membranes.
• Analyzed COF membrane applications in dyeing wastewater treatment, heavy metal removal, seawater desalination, and oil-water separation.
• Detailed separation mechanisms including pore structure, hydrophilicity/hydrophobicity, electrostatic interactions, and the Donnan effect.

Main Results:

• Each preparation method presents unique advantages and disadvantages.
• COF membranes demonstrate significant potential across various liquid separation challenges.
• Tailoring ligands allows for the design of COF membranes with specific separation capabilities.

Conclusions:

• COF membranes are highly promising for next-generation separation technologies.
• Further research is needed to address challenges and optimize COF membrane design and application.
• The ability to functionalize COFs enables precise control over membrane performance for targeted separations.