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Graphene-Based Sieve Turns Seawater Into Drinking Water (bbc.com)
An anonymous reader quotes a report from BBC: A UK-based team of researchers has created a graphene-based sieve capable of removing salt from seawater. The sought-after development could aid the millions of people without ready access to clean drinking water. The promising graphene oxide sieve could be highly efficient at filtering salts, and will now be tested against existing desalination membranes. It has previously been difficult to manufacture graphene-based barriers on an industrial scale. Reporting their results in the journal Nature Nanotechnology, scientists from the University of Manchester, led by Dr Rahul Nair, shows how they solved some of the challenges by using a chemical derivative called graphene oxide. Isolated and characterized by a University of Manchester-led team in 2004, graphene comprises a single layer of carbon atoms arranged in a hexagonal lattice. Its unusual properties, such as extraordinary tensile strength and electrical conductivity, have earmarked it as one of the most promising materials for future applications. But it has been difficult to produce large quantities of single-layer graphene using existing methods, such as chemical vapor deposition (CVD). Current production routes are also quite costly. On the other hand, said Dr Nair, "graphene oxide can be produced by simple oxidation in the lab." Graphene oxide membranes have already proven their worth in sieving out small nanoparticles, organic molecules and even large salts. But until now, they couldn't be used to filter out common salts, which require even smaller sieves. Previous work had shown that graphene oxide membranes became slightly swollen when immersed in water, allowing smaller salts to flow through the pores along with water molecules. Now, Dr Nair and colleagues demonstrated that placing walls made of epoxy resin (a substance used in coatings and glues) on either side of the graphene oxide membrane was sufficient to stop the expansion.
The biggest problem isn't removing the salt, it is what to do with all the excess salt that remains. If you dump it back into the ocean, it wipes out all sea life in a large radius. It is pretty devastating.
I'm no chemistry expert, but isn't graphene oxide simply CO2?
When our name is on the back of your car, we're behind you all the way!
Sure, but the Water Seer can turn air into drinkable water!
1. What throughput / flowrate can you achieve, per unit of area?
2. How do you clear clogging?
Desalination of seawater by reverse osmosis is an old hat. The main challenge from an energy POV is the high pressure differential (and the flow, of course) needed. This won't change much with a new membrane.
Of course, a new membrane might have other desirable properties (cost, robustness, whatever), so every new option is a Good Thing, but the abstract suggests that graphene is something new here. It isn't. Just one more tool in an old chest.
Scientist: Do you know what this means?
Nick: There'd be an *awful* lot of salt.
WARNING: Smartphones have side effects--most of them undocumented.
Reverse osmosis water filters have been around for ages, and in large scale commercial use since the 1970s.
https://en.wikipedia.org/wiki/Reverse_osmosis#History
Another graphene-is-the-material-of-the-future spectacular application that will come to absolutely nothing because or something or another. In a few months time, nobody will even remember about it.
Yes.
Come to market.
The natural process of osmosis will persist. This is the tendency for water to flow through the filter in the wrong direction (the fresh water flows into the salt water). Sea water has (I looked it up) an osmotic pressure of 28 atmospheres (411 pounds per square inch)...one must supply a pressure of this amount to stop the exfiltration. To make a substantial amount of water go through in the right direction, you'll need double this...at least 800 psi. To maintain this pressure requires a lot of energy. Usually Electricity --> motor --> pump.
It's really a new membrane for reverse-osmosis water purification. These devices are widely used in the Bahamas, Key West, thousands of other locations -- but haven't expanded widely due to high energy requirements.
allowed the chinese to take all the American sun light by solar powe and I did nothing r, Now they are going to allow poor people with access to sea water to make cheap water instead of relying on bottled water.
What are rich 1%er american IP holders going to do ? They might even have to work for a living!
Wont someone think of the rich? On day my ship might come in you filthy peasants.
Los Angeles consumed about 17,957,000,000 in August of 2013
A gallon of sear water contains 4.5 oz of salt
So if LA used exclusively desalinized water, they would have 10,100,812,500 lbs of salt on their hands (17,957,000,000*4.5/8)
This is about 126,260,156 cubic feet.
Your average Panamax cargo ship has about 3.6 million cubic feet of space.
This is about 35 ships worth of salt.
There are about 16,900 bulk carrier ships operating in the world.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
The idea you use a sieve to remove salts may be in line with current market leader reverse osmosis, but that does not mean it is better or even a good approach. Ionic desalination is 80% more efficient, it uses the charge of the ions, but because it is less energy intensive the big fossil and nuclear players keep it out of the market.
Graphene is finally worth its salt?
It's cool that you found it.
It's not exactly on the market though... the article says "The product was not expected to be released until 2020."
That that is is that that that that is not is not.