“Our ultimate goal is to make a filter device that allows a glass of drinkable water made from seawater after a few minutes of hand pumping”
Graphene has proven itself as a wonder material with a vast range of unique properties. Among the least-known marvels of graphene is its strange love affair with water.
Graphene is hydrophobic – it repels water – but narrow capillaries made from graphene vigorously suck in water allowing its rapid permeation, if the water layer is only one atom thick – that is, as thin as graphene itself.
This bizarre property has attracted intense academic and industrial interest with intent to develop new water filtration and desalination technologies.
One-atom-wide graphene capillaries can now be made easily and cheaply by piling layers of graphene oxide – a derivative of graphene – on top of each other. The resulting multilayer stacks (laminates) have a structure similar to nacre (mother of pearl), which makes them also mechanically strong.
Two years ago, University of Manchester researchers discovered that thin membranes made from such laminates were impermeable to all gases and vapours, except for water. This means that even helium, the hardest gas to block off, cannot pass through the membranes whereas water vapour went through with no resistance.
Now the same team led by Dr Rahul Nair and Prof Andre Geim has tested how good the graphene membranes are as filters for liquid water. The results appear in the latest issue (Feb 14, 2014) of Science.
The researchers report that, if immersed in water, the laminates become slightly swollen but still allow ultrafast flow of not one but two monolayers of water.
Small salts with a size of less than nine Angstroms can flow along but larger ions or molecules are blocked. Ten Angstroms is equivalent to a billionth of a metre.
The graphene filters have an astonishingly accurate mesh that allows them to distinguish between atomic species that are only a few percent different in size.
On top of this ultraprecise separation, it is also ultrafast. Those ions that can go through do so with such a speed as if the graphene membranes were an ordinary coffee filter.
The latter effect is due to a property that the Manchester scientists call “ion sponging”. Their graphene capillaries suck up small ions as powerful hoovers leading to internal concentrations that can be hundreds of times higher than in external salty solutions.
Dr Nair said: “The water filtration is as fast and as precise as one could possibly hope for such narrow capillaries. Now we want to control the graphene mesh size and reduce it below nine Angstroms to filter out even the smallest salts like in seawater. Our work shows that it is possible.”
Dr Irina Grigorieva, a co-author of the study, added: “Our ultimate goal is to make a filter device that allows a glass of drinkable water made from seawater after a few minutes of hand pumping. We are not there yet but this is no longer science fiction”.
The Latest on: Water filtration and desalination
via Google News
The Latest on: Water filtration and desalination
- Solar desalination aids water crisison November 27, 2019 at 6:25 am
However, desalination of seawater or brackish water can be an affordable solution if the source of energy ... are injected before and after sand filtration and micro-filtration, protecting the reverse ...
- EnerDynamic Hybrid Technologies Announces Delivery of Mobile Power and Water Filtration to Energia Power Solutionson November 13, 2019 at 10:00 am
NIAGARA FALLS, ON and MARYLAND, USA / ACCESSWIRE / November 13, 2019 / EnerDynamic Hybrid Technologies Corp. (TSXV:EHT) ("EHT") and Energia Power Solutions LLC ("Energia"), based in Maryland USA, with ...
- DuPont Water Solutions' Modular Ultrafiltration Design Awarded Best Disruptive Technology By International Desalination Associationon October 22, 2019 at 5:00 pm
DuPont Water Solutions, a business unit of the DuPont Safety & Construction division, was awarded the 2019 International Desalination Association (IDA) Award for Best Disruptive Technology in ...
- Desalination of Produced Water by Membrane Distillation: Effect of the Feed Components and of a Pre-treatment by Fenton Oxidationon October 18, 2019 at 2:03 am
In this study, the performance of MD is discussed for the treatment of synthetic feeds mimicking produced water effluents from ... efficiency of this innovative desalination process. Figure 1 presents ...
- Pros And Cons Of Seawater Desalination Using RO For Drinking Wateron August 29, 2019 at 10:35 am
Seawater desalination is unequivocally the future of drinking water production for coastal communities and ... The pretreatment consists of usually one or more filtration units that remove particles ...
- Technique could make better membranes for next-generation filtration and desalinationon August 21, 2019 at 4:48 am
Deriving drinkable water from seawater, treating wastewater and ... be converted to fuel or other applications while also reducing pollution. Filters like the ones used for desalination are called ...
- Wooden filtration membrane promises efficient and more sustainable water desalinationon August 5, 2019 at 10:35 pm
Current approaches to water desalination are very expensive and require huge amounts of energy. Not helping on the environmental side of things is that the membranes used to filter the water are ...
- Sheaf Filter Reduces Pre-Treatment Stages at Maagan Desalination Planton July 4, 2019 at 5:00 pm
As part of the routine treatment of the desalination plant the EBS 15000 filters are washed every 45 minutes to once an hour, depending on well water quality, and the cartridges are replaced every ...
- Inching Towards Abundant Water: New Progress in Desalination Techon June 18, 2019 at 7:58 am
In reverse osmosis, high amounts of pressure push water through a filter to separate it from salt. According to the International Desalination Association, there are 20,516 desalination plants across ...
- Is desalination realistically a help in harnessing potable water from the sea?on June 7, 2019 at 3:10 pm
A plant pumps in salty or brackish water, filters separate the salt from the water, and the salty water is returned to the sea. Fresh water is sent to households. RO desalination came about in the ...
via Bing News