Professor Nicky Eshtiaghi was working in her lab at RMIT University in Melbourne when she realized the water sample had changed. What looked cloudy and gray had become clear. The tiny plastic particles swimming through it — so small they were invisible to the human eye — were gone. In their place sat a dark, sandy material at the bottom of the beaker, attracted to a magnet like iron filings. The plastics had been captured. The water was clean.
That moment, described by researchers on the team, captures what may be one of the most practical solutions yet developed for a problem that has puzzled water scientists for years: how to remove microplastics, and especially their even tinier cousins called nanoplastics, from the water we drink, swim in, and depend on. The team's invention, described in the journal Chemical Engineering Journal, builds on a 2022 breakthrough and goes significantly further.
In laboratory testing, the material removed more than 95% of micro- and nanoplastics within one hour, including particles as small as 30 nanometers — far smaller than any previous method had managed at scale. About 80% of contaminants were captured in just the first 15 minutes of treatment, a speed that matches the contact times already used in real water treatment plants. The material also cleared more than 95% of other pollutants tested, including toxic metals like mercury and chromium, as well as dyes and ibuprofen. It worked on common plastics like polyethylene, polypropylene, and polyester, and it performed equally well in both fresh water and salt water.
The team then tested the material in something closer to real life: wastewater from an industrial laundry, which is one of the biggest sources of microplastic pollution because synthetic clothing sheds tiny fibers every time it is washed. The material removed 88% of polyester microfibers along with dyes, holding up even when surfactants and organic matter were present in the water.
Perhaps the most important feature was one that rarely makes headlines but matters enormously to industries trying to adopt new water treatment methods: recoverability. The material is magnetic, meaning it can be pulled out of treated water quickly using magnets rather than expensive and energy-intensive filtering. This opens the door to reuse — the material can be collected, cleaned, and used again rather than becoming part of a new waste stream.
The team worked with One Eye Industries, a Canadian company, to test this magnetic separation approach. Founder Roger Simonson said recovery has long been one of the biggest obstacles to bringing new water treatment technologies out of the laboratory and into real facilities. "The challenge isn't only capturing these particles," he said. "It's recovering the treatment material quickly and reliably after it has done its job, without creating a new waste stream."
The researchers are now partnering with Fire and Test Australasia, an Indigenous-owned company based in Geelong, Victoria, to explore how the technology might be used to treat stormwater and wastewater in community settings. They are also working with Australian company Star Water Group, which has clients in the United States including California, where tightening regulations are increasing demand for better microplastics treatment.
Professor Eshtiaghi said capturing nanoscale plastics was critical because existing water treatment methods cannot do it at scale. For communities facing contaminated water supplies, aging infrastructure, or plastic pollution flowing from nearby industries, this technology may offer a practical new tool. The science is moving from the lab to the real world, and the water, drop by drop, is getting cleaner.