2.1 billion people still don’t have safe drinking water.
Using a type of graphene called Graphair, scientists from Australia have created a water filter that can make highly polluted seawater drinkable after just one pass.
The technology could be used to cheaply provide safe drinking water to regions of the world without access to it.
“Almost a third of the world’s population, some 2.1 billion people, don’t have clean and safe drinking water,” said lead author Dong Han Seo.
“As a result, millions – mostly children – die from diseases associated with inadequate water supply, sanitation and hygiene every year. In Graphair we’ve found a perfect filter for water purification.
“It can replace the complex, time consuming and multi-stage processes currently needed with a single step.”
Developed by researchers at the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Graphair is a form of graphene made out of soybean oil.
Graphene – a one-atom-thick, ultrastrong carbon material – might be touted as a supermaterial, but it’s been relatively expensive to produce, which has been limiting its use in broader applications.
Graphair is cheaper and simpler to produce than more traditional graphene manufacturing methods, while retaining the properties of graphene.
One of those properties is hydrophobia – graphene repels water.
To turn it into a filter, the researchers developed a graphene film with microscopic nanochannels; these allow the water through but stop larger pollutants with larger molecules.
Then the team overlaid their new film on a typical, commercial-grade water filtration membrane to do some tests.
When used by itself, a water filtration membrane becomes coated with contaminants, blocking the pores that allow the water through. The researchers found that during their tests using highly polluted Sydney Harbour water, a normal water filter’s filtration rate halved without the graphene film.
Then the Graphair was added to the filter. The team found that the combination filter screened out more contaminants – 99 percent of them – faster than the conventional filter. And it continued to work even when coated with pollutants, the researchers said.
This eliminates a step from other filtration methods – removing the contaminants from the water before passing it through the membrane to prevent them from coating it.
This is a similar result to one found last year, where minuscule pores in a graphene filter were able to prevent salt from seawater from passing through – and allow water through faster.
“This technology can create clean drinking water, regardless of how dirty it is, in a single step,” Seo said.
“All that’s needed is heat, our graphene, a membrane filter, and a small water pump. We’re hoping to commence field trials in a developing world community next year.”
Eventually, they believe that the technology could be used for household and even town-based water filtration, as well as seawater and industrial wastewater treatment.