Biguanidine functional chitooligosaccharide modified reverse osmosis membrane with improved anti-biofouling property

Area of Science:

• Materials Science
• Membrane Technology
• Biotechnology

Background:

• Biofouling and bacterial contamination significantly reduce the efficiency and lifespan of reverse osmosis (RO) membranes.
• Developing advanced RO membranes with enhanced anti-fouling and antibacterial properties is crucial for efficient water desalination.
• Chitooligosaccharides (COS) and their derivatives offer promising bioactivity for material modification.

Purpose of the Study:

• To fabricate a novel anti-biofouling RO membrane using cationic biguanidine functional chitooligosaccharide (COSG).
• To evaluate the performance of the COSG-modified RO membrane in terms of hydrophilicity, water flux, salt rejection, and anti-fouling capabilities.
• To assess the antibacterial efficacy and long-term desalination performance of the COSG-modified membrane in challenging environments.

Main Methods:

• Fabrication of a novel RO membrane via second interfacial polymerization of synthesized COSG with acyl chloride groups on the RO membrane surface.
• Modification of RO membranes with chitooligosaccharide (COS) for comparative analysis.
• Characterization of membrane surface properties including negative charge, roughness, and hydrophilicity.
• Performance testing including water flux, salt rejection, membrane fouling tests (lysozyme, bovine serum albumin), and antibacterial assays against Escherichia coli and Bacillus subtilis.

Main Results:

• The COSG-modified membrane exhibited significantly improved hydrophilicity, reduced surface negative charge, and decreased roughness compared to the virgin membrane.
• Water flux increased by 16.61% for the COSG-modified membrane, with a slight decrease in salt rejection.
• The COSG-modified membrane demonstrated superior anti-fouling properties with low flux decline and high flux recovery ratios.
• Excellent antibacterial activity was observed, with 99.9% mortality against Escherichia coli and Bacillus subtilis.
• The modified membrane maintained high desalination performance even after seven days of immersion in bacterial suspensions.

Conclusions:

• The novel COSG-modified RO membrane effectively combats biofouling and bacterial contamination.
• The enhanced hydrophilicity and surface properties contribute to improved anti-fouling performance and water flux.
• COSG modification presents a viable strategy for developing high-performance, durable RO membranes for water treatment applications.