Researchers at RMIT University in Australia have developed a magnetic powder that can extract more than 95% of microplastics, nanoplastics and other contaminants from water in less than an hour. The reusable material targets particles as small as 30 nanometres, far smaller than those typically captured by conventional filtration, and is designed to be recovered from treated water with magnets.
Laboratory tests demonstrated removal of polyethylene and polypropylene particles, along with polyester, from freshwater and seawater. The powder captured around 80% of contaminants within the first 15 minutes. Reported target contaminants also include mercury and chromium, with copper among the heavy metals, plus ibuprofen and industrial dyes. In wastewater from an industrial laundry, the system removed more than 88% of polyester microfibres and liquid dyes despite the presence of soap and organic debris.
Addressing a Persistent Challenge
Microscopic plastic fragments can pass through treatment barriers designed to capture larger particles. Nanoplastics are especially challenging because of their small size, while industrial wastewater containing fibres and metals, as well as pharmaceutical residues or dyes, can make treatment more complex. The RMIT powder binds to contaminants so they can be separated from the water using an external magnetic field.
Initial results also suggest the powder can capture larger molecules from the PFAS group, a class of persistent chemicals. Its performance against PFAS in real-world water conditions remains an area for further study, including the effects of water chemistry and competing contaminants on capture.
Other research teams are also exploring magnetic separation. A separate experiment using magnetite mixed with waste vegetable oil reported removing about 87% of microplastics across roughly 1,000 tests in freshwater and seawater. It tested ten common plastic types, with the strongest results for washing-machine fibres and the weakest for polypropylene. That approach uses a different material from the RMIT powder, but highlights a shared engineering challenge: treatment systems must capture contaminants while reliably recovering magnetic material from large volumes of water.
Magnetic Recovery and Reuse
Recovering the treatment material is basic to the RMIT process. After the powder binds to contaminants, magnets separate it from the water so it can be cleaned and reused. Reuse may reduce material costs and limit the risk of powder escaping into treated water. Practical performance also depends on how efficiently the material can be recovered and regenerated over repeated cycles.
Research projects elsewhere are examining the same gap between laboratory demonstrations and treatment systems. The British Columbia Institute of Technology’s MagneTrap BC project, supervised by Chemistry faculty member Dr. Ali Al Jibouri, is investigating magnetic filtration for microplastics and other suspended contaminants as a potentially practical, able to grow approach. It is ongoing research, illustrating the distinction between a promising prototype and a treatment process operating at municipal or industrial scale.
Cost and Ability to grow
The latest RMIT version builds on earlier work by the team in 2022. The researchers report that switching to room-temperature manufacturing and more affordable raw materials increased production fivefold and cut costs by about 75%. Reusing the powder could further reduce operating expenses, although full-scale economics also depend on the energy and equipment needed for recovery and cleaning, as well as performance over repeated treatment cycles.
The process is designed to integrate with existing water-treatment systems and target several contaminant types in one operation. For deployment, operators would need to assess performance in wastewater with varying pollutant concentrations and mixtures, along with how captured contaminants and any residual treatment material would be managed.
Next Steps and Potential Impact
RMIT is collaborating with Fire and Test Australasia, an Indigenous-owned company in Victoria, to pilot the system in stormwater and community water networks. An agreement with Star Water Group is intended to explore applications in the United States and Europe. Potential uses include textile factories and industrial plants, along with municipal water systems and local stormwater networks.
Microplastics and nanoplastics enter waterways through the breakdown of plastic waste and synthetic clothing, as well as through industrial processes. Their size can make capture more difficult than removing larger debris through basic screening or sedimentation. By binding particles to a recoverable magnetic material, the RMIT approach is designed to intercept some of these pollutants before they move into rivers and coastal waters.
The technology is still being tested beyond the laboratory. Its reported removal rates, ability to recover and reuse the powder, and performance across different water conditions will shape whether it can become a practical treatment option at larger scale.
