Nav: Home

Ultrathin nanosheets separate harmful ions from water

June 08, 2020

  • An international research team, led by Monash University and ANSTO (Australia's Nuclear Science and Technology Organisation), has created an ultrathin membrane with high porosity that can filter potentially harmful ions from water.
  • Researchers created this ultrathin molecular sieve membrane using 2D nanosheets, developed with water-stable Metal Organic Frameworks (MOFs).
  • The membrane has potential to deliver clean water for millions of people globally through purification and desalination processes. It can also be used in the separation of gases and solvents.
In a world-first, an international research team, led by Monash University and ANSTO, has created an ultrathin porous membrane to completely separate potentially harmful ions, such as lead and mercury, from water.

This innovation could enhance the desalination process and transform the dirtiest water into something potable for millions of people across the world.

The membrane performed steadily for more than 750 hours using limited energy. It could also be manufactured on a global scale, pending further testing.

Researchers for the first time developed water-stable monolayer aluminium tetra-(4-carboxyphenyl) porphyrin frameworks (termed AI-MOFs) nanosheets, and demonstrated their near perfection as building materials for membranes in ion separation from water.

These Al-MOFs nanosheets, exfoliated to just a nanoscale in thickness (one thousand-millionths of a metre), can help remove harmful carcinogens from the atmosphere by creating highly porous membranes to facilitate the separation processes of gases and organic solvents, such as paint.

Results from the study are published in the prestigious international journal, Science Advances.

The study was led by Professor Xiwang Zhang, Researcher in the Department of Chemical Engineering at Monash University and the Director of the ARC Research Hub for Energy-efficient Separation, and Dr Qinfen Gu, Principal Scientist at ANSTO's Australian Synchrotron.

"Owing to the rich porosity and uniform pore size, Metal Organic Frameworks (MOFs) offer significant advantages over other materials for the precise and fast membrane separation," Professor Zhang said.

"However, it remains a daunting challenge to fabricate ultrathin MOFs membranes (less than 100 nanometres) for water-related processing, since most reported MOFs membranes are typically thick and suffer from insufficient hydrolytic stability.

"In this world-first study, we were able to use these ultrathin Al-MOFs to create a membrane that is permeable to water while achieving maximum porosity with nearly 100 percent rejection of ions. This study shows promise for the future application of this membrane to other filtration processes, such as gas separation."

Polymers are by far the most widespread membrane materials, largely owing to their easy processability and low cost, the study suggests.

However, traditional polymeric membranes for ion separation from water usually contain a dense selective layer, leading to limited selectivity. In contrast, nanoporous membranes, where uniform nanopores act as the sieving role, may overcome this limitation.

This breakthrough study confirms that the intrinsic nanopores of Al-MOFs nanosheets facilitate the ion/water separation by creating vertically-aligned channels as the main transport pathway for water molecules, and was enabled by the unique capability of the Australian Synchrotron to analyse materials at the molecular level.

"We use an instrument called the Powder Diffraction beamline at ANSTO's Australian Synchrotron, to understand the difference between the molecular structure of nanosheet samples, and samples at different temperatures, in order to test water purification performance," Dr Gu said.

"The technique, called in-situ, high temperature powder X-ray diffraction characterisation, was conducted on the nanosheets, and during the process there were no obvious variations in the samples at increasing temperature, demonstrating their robustness."
-end-
The research team comprises Professor Xiwang Zhang, Meipeng Jian, Ruosang Qiu, Yua Xia and Professor Huanting Wang (Monash University); Yu Chen (Monash Centre for Electron Microscopy); Dr Qinfen Gu (ANSTO, Australian Synchrotron); Chengzhi Hu (Chinese Academy of Sciences); and Ruiping Liu and Chengzhi Hu (Chinese Academy of Sciences and Tsinghua University).

MEDIA ENQUIRIES

Media
Monash University
T: +61 3 9903 4840 E: media@monash.edu
For more Monash media stories, visit our news and events site

Monash University

Related Water Articles:

'Pregnancy test for water' delivers fast, easy results on water quality
A new platform technology can assess water safety and quality with just a single drop and a few minutes.
Something in the water
Between 2015 and 2016, Brazil suffered from an epidemic outbreak of the Zika virus, whose infections occurred throughout the country states.
Researchers create new tools to monitor water quality, measure water insecurity
A wife-husband team will present both high-tech and low-tech solutions for improving water security at this year's American Association for the Advancement of Science (AAAS) annual meeting in Seattle on Sunday, Feb.
The shape of water: What water molecules look like on the surface of materials
Water is a familiar substance that is present virtually everywhere.
Water, water everywhere -- and it's weirder than you think
Researchers at The University of Tokyo show that liquid water has 2 distinct molecular arrangements: tetrahedral and non-tetrahedral.
What's in your water?
Mixing drinking water with chlorine, the United States' most common method of disinfecting drinking water, creates previously unidentified toxic byproducts, says Carsten Prasse from Johns Hopkins University and his collaborators from the University of California, Berkeley and Switzerland.
How we transport water in our bodies inspires new water filtration method
A multidisciplinary group of engineers and scientists has discovered a new method for water filtration that could have implications for a variety of technologies, such as desalination plants, breathable and protective fabrics, and carbon capture in gas separations.
Source water key to bacterial water safety in remote Northern Australia
In the wet-dry topics of Australia, drinking water in remote communities is often sourced from groundwater bores.
Our water cycle diagrams give a false sense of water security
Pictures of the earth's water cycle used in education and research throughout the world are in urgent need of updating to show the effects of human interference, according to new analysis by an international team of hydrology experts.
Water management helped by mathematical model of fresh water lenses
In this paper, the homeostasis of water lenses was explained as an intricate interaction of the following physical factors: infiltration to the lens from occasional (sporadic) rains, permanent evaporation from the water table, buoyancy due to a density contrast of the fresh and saline water, and the force of resistance to water motion from the dune sand.
More Water News and Water Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.