Ultrathin graphene-based membrane with precise molecular sieving and ultrafast solvent permeation

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Graphene oxide (GO) membranes offer unique sieving and permeation properties.
• Current GO membranes are limited to aqueous solutions due to poor organic solvent permeability.
• The underlying reasons for GO membrane impermeability to organic solvents remain unclear.

Purpose of the Study:

• To develop graphene oxide membranes capable of efficient organic solvent filtration.
• To investigate the mechanism behind organic solvent permeation through GO membranes.
• To demonstrate the potential of these membranes for organic solvent nanofiltration.

Main Methods:

• Fabrication of ultrathin graphene oxide (GO) laminates with smooth 2D capillaries using large GO flakes (10-20 μm).
• Characterization of membrane thickness down to approximately 10 nm.
• Testing permeation rates for water and organic solvents, and rejection of organic dyes in methanol.

Main Results:

• Achieved exceptionally thin GO membranes (∼10 nm) allowing fast permeation of both water and organic solvents.
• Identified randomly distributed pinholes interconnected by 1 nm wide graphene channels as responsible for organic solvent permeation.
• Demonstrated >99.9% rejection of small molecular weight organic dyes in methanol, showcasing nanofiltration capabilities.

Conclusions:

• Ultrathin GO laminates with specific structural features enable efficient organic solvent filtration.
• The findings overcome previous limitations, expanding the application scope of GO membranes.
• This research significantly broadens the potential use of GO membranes in advanced purification and filtration technologies.