- Title: Graphene sieve could make sea water drinkable
- Date: 30th May 2017
- Summary: MANCHESTER, ENGLAND, UK (RECENT) (REUTERS) VARIOUS OF CLEAN WATER DRIPPING INTO CONTAINER (2 SHOTS) (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "We take a dirty, oily water mixture and we pass this water through a pump. This pump is basically pumping this water through this membrane. This is a graphene oxide membrane and the water goes through and what we get is the clean water coming out here and the dirty water comes back to here." WATER FILTRATION UNIT (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "The problem was that when you put the membrane in water the sieve became larger. Now we've solved that problem, so now we can take this salty water, put it back in our new filtration unit, where we can filter out even the smallest sodium chloride." VARIOUS OF NAIR HOLDING GRAPHENE OXIDE MEMBRANE (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "Because this membrane works on a different principle, a physical sieving principle and the sieve is so small, in principle we can use one membrane to filter out all molecules including large and small molecules so we can forget about that unit in future. We only need one unit which can remove all the contamination including the smallest sodium chloride." NAIR POINTING TO OUTLETS ON FILTRATION UNIT (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "What graphene brings is a more efficient process, so water filtration through the graphene membrane is much faster than the commercial polymer membrane which means you get more drinking water in short period of time, and the pressure required to make that drinking water is smaller than what the commercial membrane does." DIRTY WATER IN CONTAINERS NAIR AND COLLEAGUE LOOKING AT WATER FILTRATION UNIT (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "But of course currently the price is slightly higher. This is because the consumption of the material is low. So in future, if you scale up this process and if you want to use this material, the price will definitely go down." DIRTY WATER IN CONTAINERS (SOUNDBITE) (English) PROFESSOR OF MATERIALS PHYSICS AT UNIVERSITY OF MANCHESTER, RAHUL RAVEENDRAN NAIR, SAYING: "It would be really nice if we could come up with a portable water filtration device - something similar, but without this gas cylinder. If you can have a hand pump or something like that then we can filter out dirty water from clean water. That is probably our long term goal."
- Embargoed: 13th June 2017 10:53
- Keywords: graphene University of Manchester water filtration graphene sieve
- Location: MANCHESTER, ENGLAND, UK / FILE LOCATIONS
- City: MANCHESTER, ENGLAND, UK / FILE LOCATIONS
- Country: United Kingdom
- Topics: Science
- Reuters ID: LVA0016J15QVV
- Aspect Ratio: 16:9
- Story Text: Scientists have developed a 'sieve' made from an oxidised form of 'wonder material' graphene that can filter dirty water and seawater to provide drinking water.
The researchers from the UK's University of Manchester developed a membrane using graphene oxide with pores small enough to filter out common salts.
Graphene, which is just one atom thick, is strong, highly flexible, electrically conductive and transparent.
Like current commercial polymer membranes used in desalination processes, graphene oxide membranes developed in the past were unable to filter salts because they swell when immersed in water. This made the pores in the membrane too large.
Now, the scientists say they have developed the 'sieve' further, so that nanoparticles like salts can be filtered out of water.
"This membrane works on a physical sieving principle and the sieve is so small, in principle we can use one membrane to filter out all molecules including large and small molecules. We only need one unit to remove all the contamination including the smallest sodium chloride," said Professor Rahul Nair, who led the research.
The researchers made the membrane by layering flakes of graphene oxide and coating them with epoxy resin to prevent swelling in water.
They pumped an oily water mixture through the graphene oxide membrane to filter out larger molecules. Then the remaining salty water was pumped through a second filter to sieve out smaller sodium chloride and other salt molecules.
Water forms what the scientists call a shell of water molecules around the salt molecules and the tiny pores of the graphene membrane are small enough to block the salt molecule while allowing the water to flow through, making the membrane ideal for desalination.
"Water filtration through the graphene membrane is much faster than the commercial polymer membrane which means you get more drinking water in a short period of time, and the pressure required to make that drinking water is smaller," he told Reuters.
Nair said that the fabrication of the membrane can be scaled up to an industrial level, which should see a fall in the cost of the materials. Its efficiency and low energy requirements could lead to a revolution in desalination technology.
The researchers hope that the 'sieve' could play a part in providing clean drinking water for millions of people around the world who do not have access to safe drinking water.
Nair envisages a smaller filtration unit for use in developing countries, where expensive large-scale desalination plants are not an option.
"It would be really nice if we could come up with a portable water filtration device. If you can have a hand pump or something like that then we can filter out dirty water from clean water. That is probably our long term goal," he said.
The challenge for researchers is to find a partner in industry to scale up production of the membrane and combine the two stages of filtration used in the lab in one unit.
The United Nations predicts that globally 1.8 billion people will experience water scarcity by 2025. - Copyright Holder: REUTERS
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