HKBU develops new catalytic membrane that boosts efficiency of cleaning wastewater using oxygen

HONG KONG, May 20, 2025 /PRNewswire/ -- A research team led by Hong Kong Baptist University (HKBU) has developed a novel catalytic membrane that can substantially boost the efficiency of cleaning wastewater using a modified advanced oxidation process (AOP). The invention contributes to the effort of tackling environmental pollution problems by offering a safer, more cost-effective, and environmentally friendly solution for wastewater treatment.

The research findings have been published in the international academic journal Advanced Functional Materials.

Novel technology targeting phenolic pollutants

Water pollution is a pressing environmental issue. Phenolic compounds are a major group of pollutants that pose a significant threat to the world's potable water supply. They are widely present in industrial effluents, agricultural runoff and municipal wastewater. They can persist in the environment for long periods, accumulate in living organisms and pose significant risks to human health and water quality. Traditional methods for removing phenolic pollutants often require hazardous chemicals or energy-intensive processes.

AOPs have been increasingly recognised and developed over the past few decades to remove pollutants from water. They are a set of chemical treatment methods which activate oxidants into reactive oxygen species (ROS) that can be used to break down pollutants in wastewater. Among these ROS, singlet oxygen (¹O₂) is particularly effective in targeting phenolic compounds.

More efficient in generating ROS

However, existing methods to generate ROS usually require strong oxidants and energy inputs as catalysts, which can be costly and environmentally unfriendly. Moreover, traditional AOP systems face two significant challenges: the inefficient transfer of molecular oxygen (O₂) in water due to its low solubility, and the difficulty in getting pollutants to interact with the catalyst surface due to the surrounding water film as a barrier.

In response to these issues, a research team led by Professor Zhao Jun, Associate Professor of the Department of Biology at HKBU, has developed a novel catalytic membrane named "NGCF-OV". It is made from a composite material that combines two advanced materials, N-doped reduced graphene oxide and cobalt ferrite. This membrane offers a promising solution for AOP and addresses the challenge of efficiently activating molecular oxygen to become ¹O₂.

Proven efficacy in degrading bisphenol A

The NGCF-OV membrane contains unique sites (asymmetric Co-OV-Fe sites) that can adjust the bond length of O_2, i.e., the distance between the centres of the two oxygen atoms that are bonded together, and thus facilitate faster and more efficient electron transfer. As a result, ¹O₂ can be produced without the need for other catalytic agents and external energy inputs. Additionally, the membrane also features graphitic nitrogen sites that trap pollutants close to the membrane's surface. The distance between the pollutants and the ¹O₂ molecules generated is therefore significantly reduced, overcoming the water film barrier issue with reaction efficiency greatly improved. 

The NGCF-OV membrane demonstrated superior efficiency in generating and utilising ¹O₂ for pollutant degradation. Test results show that this novel technology can completely degrade bisphenol A, a common and harmful pollutant, in just 86 milliseconds (one thousandth of a second), outperforming many existing cleanup methods.

More sustainable and efficient wastewater treatment

Professor Zhao said: "This research marks a significant advancement in the field of water treatment and represents a promising strategy for addressing environmental pollution. By effectively integrating the processes of O₂ activation and pollutant degradation within a single membrane, this technology offers a more sustainable and efficient approach to treating contaminated water.

"The ability to generate reactive oxygen species without external energy inputs makes this membrane particularly suitable for emergency pollution remediation and everyday water treatment applications," he added.

Application of the NGCF-OV membrane is not limited to the degradation of a specific pollutant like bisphenol A. Instead, its catalytic properties can be harnessed for the degradation of a variety of organic pollutants in wastewater, such as antibiotics, pesticides, dyes, etc. It paves the way for more advanced practical pollution remediation technologies and contributes to the broader goal of protecting public health and preserving the environment.

SOURCE Hong Kong Baptist University