A new type of graphene-based filter could be the key to managing the global water crisis, a study has revealed. The new graphene filter, which has been developed by Monash University and the University of Kentucky, allows water and other liquids to be filtered nine times faster than the current leading commercial filter.
According to the World Economic Forum’s Global Risks Report, lack of access to safe, clean water is the biggest risk to society over the coming decade. Yet some of these risks could be mitigated by the development of this filter, which is so strong and stable that it can be used for extended periods in the harshest corrosive environments, and with less maintenance than other filters on the market.
The research team was led by Associate Professor Mainak Majumder from Monash University. Associate Professor Majumder said the key to making their filter was developing a viscous form of graphene oxide that could be spread very thinly with a blade.
“This technique creates a uniform arrangement in the graphene, and that evenness gives our filter special properties,” Associate Prof Majumder said.
This technique allows the filters to be produced much faster and in larger sizes, which is critical for developing commercial applications. The graphene-based filter could be used to filter chemicals, viruses, or bacteria from a range of liquids. It could be used to purify water, dairy products or wine, or in the production of pharmaceuticals.
This is the first time that a graphene filter has been able to be produced on an industrial scale – a problem that has plagued the scientific community for years.
(a) Viscoelastic property of GO (~40 mg ml−1). Scale bar, 1 cm. (b) Zero-shear viscosity of the dispersions increases with increasing GO concentration. Dashed line is a polynomial fit. (c) Rheology data for three different concentration showing shear-thinning behavior. Solid curves are the fit of the experimental data with a power law model. (d) Schematic of shear-alignment processing of a nematic GO to a film; L is the width of blade, h0 is the height of the channel, H is the height of the fluid in front of the blade and U is the processing speed. (e) Polarized light images of fully nematic GO at 40 mg ml−1 (scale bar, 1 μm). (f) The red circle in the photograph identfies dewetting spots in the SAMs, which is eliminated when processed from liquid crystalline GO (scale bars, 1 cm). (g) An SEM image demonstrates continuity and conformity of SAM over a porous Nylon substrate (scale bar, 1 μm). (h) Photograph of the gravure printing machine and (inset) images of 13 × 14 cm2 GO membranes with different thicknesses. (i,j) AFM height map and corresponding height profiles of our membrane (scale bar, 1 μm).
“It’s been a race to see who could develop this technology first, because until now graphene-based filters could only be used on a small scale in the lab,” Mr Akbari said.
Graphene is a lattice of carbon atoms so thin it’s considered to be two-dimensional. It has been hailed as a “wonder-material” because of its incredible performance characteristics and range of potential applications.
The team’s new filter can filter out anything bigger than one nanometre, which is about 100,000 times smaller than the width of a human hair.
The research has gathered interest from a number of companies in the United States and the Asia Pacific, the largest and fastest-growing markets for nano-filtration technologies.
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