Stronger than chlorine: Tiny nanoparticles tackle big water problems

Tiny nanoparticles developed by researchers at the University of Waterloo have successfully cleaned up water contaminated with some of the world’s nastiest pollutants.

The research team, led by Frank Gu, Canada Research Chair, associate professor of chemical engineering in the Faculty of Engineering and member of the Waterloo Institute for Nanotechnology (WIN), which has a host of possible applications — from public water treatment to toxic spill remediation.

“It has the potential to prevent a great deal of damage to humans and their environment,” says researcher Tim Leshuk, a PhD student in chemical engineering and recent recipient of the prestigious Vanier Canada Graduate Scholarship.

As an undergraduate, Leshuk wanted to find ways to treat cancer but the technology he helped develop with Gu may actually prevent cancer and a host of other illnesses.

“Water chlorination technology has saved more lives around the world than any other health innovation,” Leshuk says. “I find this pretty inspirational.”

Nanoparticles rip apart pollutants

Pesticides, pharmaceuticals, and industrial pollutants all accumulate in our water supply and, currently, there’s no way to filter them out. The nanoparticles invented by the Waterloo research team, called photocatalysts, have cleared water samples of hormone disruptors and pharmaceuticals, and tests are being run on industrial wastewater.

Less than a gram of these nanoparticles can filter a litre of water and because they’re catalysts, they can be used again and again — indefinitely, in fact.

“They harvest sunlight and spew out a mixture of highly-reactive free radicals, which are much more powerful than chlorine and which can rip apart these persistent chemicals into nontoxic components,” Leshuk explains.

Magnetic nanoparticles can be removed from treated water

The problem, until now, has been removing the photocatalysts from the water after they’ve done their work; as Leshuk puts it: “That’s the definition of a pollutant.” To address this, he has given a magnetic core to each nanoparticle. When their work is done, the photocatalysts can be pulled from the water with a magnet.

Though the technology is advanced, the process is simple: “Put the nanoparticles in the polluted water, shine light on them to activate their purification, and then sweep the particles out with a magnet.”