06-08-2019 - A research team led by the University of Adelaide has developed a new approach to clean water from microplastics that pollute it without harming the microorganisms nearby.
Plastic waste enters oceans and rivers and poses a global environmental threat that has health consequences for animals, humans and ecosystems.
The researchers have developed a technique to break up the microplastics with tiny coil-shaped carbon-based magnets. Her work is published in the journal Matter.
"Microplastics adsorb organic and metallic contaminants on their way through the water and release these dangerous substances to aquatic organisms when consumed, causing them to accumulate throughout the food chain," says senior author Shaobin Wang, professor of chemical engineering at the University of Shanghai Adelaide. "Carbon nanosprings are strong and stable enough to break down these microplastics into compounds that do not pose such a threat to the marine ecosystem."
Although microplastics are often invisible to the naked eye, they are ubiquitous pollutants. Some, such as the exfoliating pearls found in popular cosmetics, are simply too small to be filtered out during industrial water treatment. Others occur indirectly when larger deposits such as soda bottles or tires lie in the sun and sand.
The research is a collaboration between the University of Adelaide, Curtin University, Edith Cowan University and Guangdong University of Technology in China.
To break down the microplastics, researchers had to produce short-lived chemicals, called reactive oxygen species, which trigger chain reactions that break down the various long molecules that make up microplastics into tiny, harmless segments that dissolve in water. Reactive oxygen species, however, are often made using heavy metals such as iron or cobalt, which in themselves constitute hazardous pollutants and are therefore unsuitable for the environment.
To address this challenge, researchers found a more environmentally friendly solution in the form of nitrogen-spiked carbon nanotubes to promote the generation of reactive oxygen species. The carbon nanotube catalysts are in the form of feathers and remove a significant amount of microplastics in just eight hours. At the same time, they remain stable even under the harsh oxidative conditions required for microplastic degradation. The wound shape increases stability and maximizes the reactive surface area. As a bonus, the tiny sources became magnetic by trapping a small amount of manganese far from the surface of the nanotubes to prevent them from leaking into the water.
"Having magnetic nanotubes is particularly exciting because it's so easy to collect from real wastewater streams to repeatedly use them for environmental remediation," says project leader dr. Xiaoguang Duan, Research Fellow at Adelaide University's School of Chemical Engineering and Advanced Materials.
Since no two microplastics are chemically identical, the researchers' next steps will be to ensure that the nanosprings work with microplastics of different composition, shape, and origin. They also intend to rigorously confirm the non-toxicity of chemical compounds that occur as intermediates or by-products in the decomposition of microplastics.
The researchers also say that these intermediates and by-products could be used as a source of energy for microorganisms that are currently plagued by environmentally damaging plastics. "If plastic contaminants can be reused as food for algae growth, it is a triumph to use biotechnology to solve environmental problems in an environmentally friendly and cost-effective manner," says Professor Wang.
Addressing the challenge of environmental sustainability is a strategic priority for the University of Adelaide.
This work was supported by the Australian Research Council, the National Natural Science Foundation of China, and the Science and Technology Program of Guangdong Province.
Contact Details
Professor Shaobin Wang
Email: [email protected]
Website: https://researchers.adelaide.edu.au/profile/shaobin.wang
Professor of Chemical Engineering
School of Chemical Engineering and Advanced Materials
The University of Adelaide
Business: 83133810
Dr Xiaoguang Duan
Email: [email protected]
Website: https://researchers.adelaide.edu.au/profile/xiaoguang.duan
Research Fellow
School of Chemical Engineering and Advanced Materials
The University of Adelaide
Mobile: + 61 (0) 416276866
Ms. Robyn Mills
Email: [email protected]
Media and Communications Officer
The University of Adelaide
Business: + 61 8 8313 6341
Mobile: + 61 410 689 084
Text and image: University of Adelaine
