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Researchers develop novel reverse osmosis membrane to reduce biofouling

A research team led by Prof. Wan Yinhua from the Institute of Process Engineering (IPE) of the Chinese Academy of Sciences has developed a dual-functional reverse osmosis (RO) membrane with enhanced antibacterial and antiadhesion properties. The membrane demonstrates broad-spectrum, sustained antibacterial activity, as well as resistance to various foulants. These properties make it suitable for water purification, seawater desalination, and high-salinity wastewater treatment, among other applications.

The findings are in the Journal of Membrane Science.

A key challenge in RO technology is the increased energy consumption and operational costs caused by membrane fouling. This fouling typically arises from a combination of organic adsorption, inorganic precipitation, and microbial growth, with biofouling accounting for over 45% of the problem. The rapid proliferation of microorganisms and the challenges associated with effective removal through pretreatment contribute to this issue.

To address this challenge, the researchers prepared a dual-functional RO membrane with excellent antibacterial and antiadhesion properties by simultaneously grafting ionic liquid and sulfonic acid monomers onto the surface of the RO membrane, using a simple redox radical polymerization.

This innovation overcomes the "trade-off" effect, resulting in increased flux without compromising salt rejection. The membrane's improved hydrophilicity, smoother surface, and reduced surface charge help it resist fouling from bovine serum albumin, humic acid, and sodium alginate.

Meanwhile, the membrane also demonstrated good antibacterial activity against E. coli and S. aureus, thanks to the antibacterial properties of the polyionic liquid segments.

"Our membrane shows higher treatment flux and a lower flux decline rate in tap water purification compared to a commercial RO membrane. After alkaline washing, the membrane flux can also be completely restored and maintain a bactericidal rate of 99.8% against E. coli," said Dr. Chen Xiangrong of IPE, corresponding author of the study.

In summary, this research has the potential to improve the efficiency of RO systems, thereby contributing to more effective and sustainable water treatment solutions.