Highly stable graphene-oxide-based membranes with superior permeability.

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Growing global demand for fresh water presents significant challenges for drinking and agriculture.
• Graphene oxide (GO) membranes show promise for desalination and water purification but face limitations in permeability and stability.
• Existing GO membranes often suffer from poor water permeability and delamination in aqueous environments.

Purpose of the Study:

• To develop robust and highly permeable reduced graphene oxide (rGO) membranes for efficient water purification.
• To enhance the interlayer distance of GO membranes to improve water flux without compromising separation performance.
• To create stable rGO membranes resistant to delamination in various chemical conditions.

Main Methods:

• Fabrication of reduced graphene oxide (rGO) membranes using theanine amino acid and tannic acid.
• Theanine and tannic acid served as reducing agents and cross-linkers to modify the GO structure.
• Characterization of membrane performance, including water permeance and rejection of organic dyes (rhodamine B, methylene blue).
• Assessment of membrane stability in aqueous solutions, including acidic and basic conditions.

Main Results:

• The fabricated rGO membranes exhibited significantly enlarged interlayer distances.
• Achieved ultrahigh water permeance exceeding 10,000 L m⁻² h⁻¹ bar⁻¹, which is 10-1000 times higher than existing membranes.
• Demonstrated excellent separation efficiency with ~100% rejection of rhodamine B and methylene blue.
• The membranes showed remarkable stability, with no damage or delamination observed in water, acid, and basic solutions for extended periods (months).

Conclusions:

• The developed theanine and tannic acid-modified rGO membranes offer a breakthrough in water purification technology.
• These membranes overcome the trade-off between permeability and selectivity, providing high flux and efficient contaminant removal.
• The enhanced stability of these rGO membranes in diverse chemical environments makes them suitable for long-term, real-world water treatment applications.