In a world first, Australian researchers have developed a graphene-based filter that can be commercially produced, and works nine times faster than current leading commercial filter units.
Researchers at Monash University and the University of Kentucky developed the new graphene filter, which is strong and stable enough to be used for extended periods of time in the harshest corrosive environments, yet requiring less maintenance than other filters on the market.
Graphene is a lattice of carbon atoms so thin that it can be considered to be two-dimensional. The new filter made from this material can filter out anything bigger than one nanometre, which is about 100,000 times smaller than the width of a human hair.
Particular advantages of graphene-based membranes include ultrafast water transport, and precise molecular sieving of gas and dissolved molecules, which makes it a great material for separation of materials.
By enabling both low-maintenance and accelerated filtration of water, this technology could help mitigate one of the most urgent crises currently facing parts of the world, which is a lack of access to safe, clean water.
While the capabilities of graphene filters have been known for years, they have been difficult and expensive to produce this far: most graphene filters could only be used on a small scale in the lab. This is the first time that a graphene filter has been developed that can be produced on an industrial scale.
Associate Professor Mainak Majumder from Monash University led the research team. According to him, the key to making the filter was developing a viscous form, the discotic nematic phase of graphene oxide, that could be spread very thinly with a blade to form highly ordered, continuous and thin films of multi-layered graphene oxide on a support membrane.
“This technique creates a uniform arrangement in the graphene, and that evenness gives our filter special properties,” Associate Prof Majumder said.
In addition, this technique allows the filters to be produced much faster and in large sizes, 13 by 14 cm2 in less than five seconds, which means these graphene filters can be produced for commercial applications. It is possible during manufacturing to control the thickness of the filter, and get a sharper cut-off in separation. Additionally, only water needs to be used as the casting solvent, making the manufacturing process more cost-effective and environmentally friendly.
This filter works with substances other than water — it can be used to filter chemicals, viruses or bacteria from a range of liquids, whether it be dairy products, wine, or pharmaceuticals.
This development has gathered interest from commercial players in the United States and the Asia Pacific, which are the largest and fastest-growing markets for nano-filtration technologies.
The team’s research was supported by industry partner Ionic Industries, as well as a number of Australian Research Council grants.
The next step will be to get the graphene-based filter on the market, with Ionic Industries testing how the filter fares against specific contaminants.