Featured Research

from universities, journals, and other organizations

Graphene's love affair with water: Water filters allow precise and fast sieving of salts and organic molecules

Date:
February 13, 2014
Source:
University of Manchester
Summary:
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.

Water easily evaporates through graphene oxide membranes but they represent an impermeable barrier for other molecules.
Credit: Dr Rahul R.Nair

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.

Related Articles


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."


Story Source:

The above story is based on materials provided by University of Manchester. Note: Materials may be edited for content and length.


Journal Reference:

  1. R. K. Joshi, P. Carbone, F. C. Wang, V. G. Kravets, Y. Su, I. V. Grigorieva, H. A. Wu, A. K. Geim, R. R. Nair. Precise and Ultrafast Molecular Sieving Through Graphene Oxide Membranes. Science, February 14, 2014 DOI: 10.1126/science.1245711

Cite This Page:

University of Manchester. "Graphene's love affair with water: Water filters allow precise and fast sieving of salts and organic molecules." ScienceDaily. ScienceDaily, 13 February 2014. <www.sciencedaily.com/releases/2014/02/140213142229.htm>.
University of Manchester. (2014, February 13). Graphene's love affair with water: Water filters allow precise and fast sieving of salts and organic molecules. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2014/02/140213142229.htm
University of Manchester. "Graphene's love affair with water: Water filters allow precise and fast sieving of salts and organic molecules." ScienceDaily. www.sciencedaily.com/releases/2014/02/140213142229.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

3D Printed Cookies Just in Time for Christmas

3D Printed Cookies Just in Time for Christmas

Reuters - Innovations Video Online (Dec. 18, 2014) A tech company in Spain have combined technology with cuisine to develop the 'Foodini', a 3D printer designed to print the perfect cookie for Santa. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. Video provided by Newsy
Powered by NewsLook.com
Los Angeles Police To Receive 7,000 Body Cameras

Los Angeles Police To Receive 7,000 Body Cameras

Newsy (Dec. 17, 2014) Los Angeles Mayor Eric Garcetti announced the cameras will be distributed starting Jan. 1. Video provided by Newsy
Powered by NewsLook.com
Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Buzz60 (Dec. 17, 2014) Jaguar unveils a virtual 360 degree windshield that may be the most futuristic automotive development yet. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins