Charge- and Size-Selective Molecular Separation using Ultrathin Cellulose Membranes

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Preparing defect-free microporous membranes thinner than 20 nm with high flux and selectivity remains a significant challenge.
• Existing membrane technologies often struggle to balance permeability and separation efficiency at the nanoscale.

Purpose of the Study:

• To report the novel application of cellulose membranes for the selective separation of small molecules.
• To demonstrate the fabrication and performance of an ultra-thin, freestanding cellulose membrane.

Main Methods:

• Regeneration of trimethylsilyl cellulose (TMSC) to form a freestanding cellulose membrane.
• Transferring the membrane to a porous alumina support for flux and selectivity measurements.
• Filtration experiments to evaluate size-sieving capabilities and molecular discrimination.

Main Results:

• A freestanding cellulose membrane as thin as 10 nm was successfully prepared.
• The membrane exhibited a high normalized flux of 700 L m⁻² h⁻¹ bar⁻¹ when supported.
• Precise size-sieving performance with estimated pore sizes between 1.5-3.5 nm and perfect discrimination of anionic over neutral molecules were achieved.

Conclusions:

• Ultra-thin cellulose membranes are a promising platform for high-performance small molecule separation.
• The developed membrane fabrication method offers high reproducibility, scale-up potential, and excellent long-term stability.
• This work addresses the challenge of creating thin, defect-free membranes for advanced separation applications.