Ionic Covalent Organic Framework-Based Membranes for Selective and Highly Permeable Molecular Sieving.

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Two-dimensional covalent organic frameworks (COFs) offer potential for molecular sieving membranes due to their tunable pores and high surface areas.
• Developing free-standing COF membranes with high permselectivity remains a challenge.
• Ionic functionalization of COF membranes can enhance separation performance.

Purpose of the Study:

• To synthesize a free-standing TpPa-SO3H COF membrane with vertically aligned nanochannels.
• To investigate the effect of sulfonic acid groups on the membrane's sieving performance and stability.
• To explore the application of this COF membrane in advanced separation processes.

Main Methods:

• Fabrication of a free-standing TpPa-SO3H COF membrane.
• Characterization of the membrane's structure, including vertically aligned nanochannels.
• Evaluation of the membrane's performance in separating water-soluble drugs and dyes based on charge and size.

Main Results:

• The synthesized TpPa-SO3H COF membrane possesses vertically aligned one-dimensional nanochannels.
• The sulfonic acid groups impart negative charge sites, leading to high water flux and excellent sieving selectivity for charged molecules.
• The membrane demonstrates long-term stability, fouling resistance, and recyclability in rejection tests.

Conclusions:

• The developed free-standing COF membrane with ionic functionalization is highly effective for advanced molecular sieving.
• This work highlights the importance of ionic ligands in designing COF membranes for diverse separation applications.
• The findings offer insights for creating next-generation separation membranes.