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Making Saltwater Drinkable With Graphene

samzenpus posted more than 2 years ago | from the water-water-everywhere dept.

Science 303

An anonymous reader writes "Graphene once again proves that it is quite possibly the most miraculous material known to man, this time by making saltwater drinkable. The process was developed by a group of MIT researchers who realized that graphene allowed for the creation of an incredibly precise sieve. Basically, the regular atomic structure of graphene means that you can create holes of any size, for example the size of a single molecule of water. Using this process scientist can desalinate saltwater 1,000 times faster than the Reverse Osmosis technique."

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Comment Subject: (-1)

Anonymous Coward | more than 2 years ago | (#40510707)

Comment:

A foul subject. (5, Interesting)

Anonymous Coward | more than 2 years ago | (#40510717)

So how durable is this membrane when it comes to dealing with impurities?

Re:A foul subject. (5, Informative)

Anonymous Coward | more than 2 years ago | (#40510759)

Graphene membranes are highly durable. The main problem would be clearing the inlet side of the filter from the buildup of blocked particles.

Prevous Slashdot article here: http://science.slashdot.org/story/12/01/27/1354240/graphene-membranes-superpermeable-to-water

http://www.manchester.ac.uk/research/news/display/?id=7895

http://arxiv.org/ftp/arxiv/papers/1112/1112.3488.pdf

Re:A foul subject. (-1)

Anonymous Coward | more than 2 years ago | (#40511187)

Periodic backwashing?

Re:A foul subject. (5, Insightful)

Anonymous Coward | more than 2 years ago | (#40510787)

Surely it won't last forever, but the membrane lifetime could be extended by using normal filters to retain impurities, and let the graphene deal with pure saline water. Maybe the graphene filter can be cleaned a couple of times and be reutilized.

Re:A foul subject. (-1)

flyneye (84093) | more than 2 years ago | (#40510927)

I agree,getting salt out is fine, but, fishy smell, fish pee, industrial pollution (mercury 'n'such ). Will anything break it down quickly enough to render it useless in short order? Murphys laws apply to most good news, where is our caveat inevitable?

Re:A foul subject. (5, Insightful)

Gr8Apes (679165) | more than 2 years ago | (#40510941)

All of those would be larger molecules than H20, don't you think? This is a pretty cool discovery/invention.

Re:A foul subject. (5, Insightful)

Anonymous Coward | more than 2 years ago | (#40510995)

I agree,getting salt out is fine, but, fishy smell, fish pee, industrial pollution (mercury 'n'such ).

Err, no one does that... Seriously. Fishy smell? Fish pee? wtf??

Mercury is not toxic much anyway, unless it is in organic forms.

But then on the plus side, if Uranium cost were > $350/lb, it would be economical to mine Uranium from sea water. It doesn't mean this concentration is toxic for you.

Where I live, most of the water is from a lake, with fish pee and moose pee all mixed in together. haha

Re:A foul subject. (0, Redundant)

Anonymous Coward | more than 2 years ago | (#40511303)

I dont dring water, the fishes shits in it. Drink beer!.

Re:A foul subject. (4, Interesting)

similar_name (1164087) | more than 2 years ago | (#40511353)

A mulit-filter process is likely to be used and while I didn't RTFA the summary says different hole sizes can be made so you might be able to fine tune it for each thing you want to filter. Imagine running sea water through a process that isolates different molecules. Not only do you get salt out of water so that you get salt and water you might be able to separate other useful things out along the way.

Re:A foul subject. (3, Informative)

marcosdumay (620877) | more than 2 years ago | (#40511091)

Well, TFA brings absolutely no detail. It won't even let you know it it is about something produced in a lab, some theoretical contruction, or even if nobody has no idea how to create such a filter.

Now, graphene is pretty stable. It probably cloges with time, as other athoms get in the place of carbon, but that is an incredibly slow process. A membrane composed of a single graphene sheet should last more than any other component of your plant.

Ok, all the above is great, and etc. But when you get in the real world, membranes get old because of impurities that accumulate on its porous. A single graphene sheet has nowhere for those impurities to accumulate, if you reverse whash it, all impurities are gone (except for the mechanism at the above paragraph). But no practical membrane is composed of a single graphene sheet, thus, durability will be probably all over the scale depending on the quality of the actual membrane, from trash that can't be used on a lab to as good as ceramic filters.

"scientist" (5, Funny)

Anonymous Coward | more than 2 years ago | (#40510721)

Using this process scientist can desalinate saltwater 1,000 times faster than the Reverse Osmosis technique.

Well isn't that swell for 'scientist', but does scientist plan to share?

Re:"scientist" (4, Funny)

axlr8or (889713) | more than 2 years ago | (#40511231)

Don't worry, they are meeting with Apple execs as we speak to save the world. It will be called, the iDsalter. The commerical will be giving a can of Redbull to an astronaut, and kicking him out the airlock of the ISS with a parachute and a pair of augmented reality googles, bluetooth paired to an iPad so he can watch ads all the way down while recording his POV.

Re:"scientist" (2, Insightful)

Anonymous Coward | more than 2 years ago | (#40511343)

Wow. You have no sense of humor.

Let's break down why you are unfunny.
  1. Starting with Apple execs, it's obvious you are trying to be funny, so hopefully the last half of the sentence will be funny. Oh but the punchline is "to save the world." Hmm, not funny at all.
  2. You try to recover from that bomb with the old Apple-prepending-i-for-all-their-products gag. But you wedge a D clumsily in there. Now, it's confirmed you've got nowhere to go but down, Dane Cook style with a completely unnecessary story that serves to only distract stupid people from your previous disasters.
  3. As expected, you begin a painfully lame story about a surreal commercial, because surrealist humor will win you all the hipsters at least right?
  4. To salvage this miserable post, you bet that other Slashdot neckbeards will moderate your post up for that witty reference to Google glasses.

At this point, you're really hoping people have forgotten that this was supposed to be some kind of joke about Apple and desalination to compensate for your complete lack of knowledge in the subfield of materials science that is detailed in the story.

Re:"scientist" (0)

Anonymous Coward | more than 2 years ago | (#40511247)

but does scientist plan to share?

Not even if he is in the same swarm.

Holes? (3, Insightful)

Anonymous Coward | more than 2 years ago | (#40510731)

what about the holes getting blocked by minerals and impurities? seems high maintenance job.

Re:Holes? (3, Insightful)

PPH (736903) | more than 2 years ago | (#40510797)

Backflush?

Re:Holes? (5, Interesting)

sam_handelman (519767) | more than 2 years ago | (#40510845)

A couple of people have raised this issue, and it relies on a fundamental mis-understanding of how the universe works on a molecular scale.

  Suppose that I have my colander and I wash some vegetables in it. Gunk can get stuck in the holes and it has to be washed off, which requires a fair amount of work because I have to break the interaction between the gunk and the surface. That's your macroscopic intuition about how filters and such work.

  But your macroscopic intuition will lead you astray in this case. The individual holes in graphene do not work that way; yes, occasionally, molecules of one kind or another will spend some time stuck to the graphene (a useful phenomenon in other circumstances - http://en.wikipedia.org/wiki/High-performance_liquid_chromatography [wikipedia.org] ) but, on the scale of atoms, they are effectively in a high-powered washing machine ALL THE TIME.

  Can't find quite the movie I want... this'll do:
http://protonsforbreakfast.wordpress.com/2012/04/11/brownian-motion-observed-in-milk/ [wordpress.com]

  So you see those oil bubbles wiggling around? Given that amount of constant wiggle, are you worried about having them "stuck" anywhere? That's thermal vibration from being at room temperature. Those milk bubbles are over 1,000 water molecules across, so each of those "wiggles" is 10 or 100 times the size of an individual graphene pore; are you worried about anything another 1000x smaller being "stuck" anywhere? It would be like worrying about gunk stuck in your colander while your colander was sitting in a fire-hose 24/7.

  Anyway- to cut to the chase:
obviously you could have you take the graphene and you run the sea water *past* it at high pressure. Occasionally some gunk gets in there but it washes away sooner or later; and nothing spends any appreciable amount of time stuck in an individual graphene hole.

Re:Holes? (1)

Onymous Hero (910664) | more than 2 years ago | (#40511079)

It would be like worrying about gunk stuck in your colander while your colander was sitting in a fire-hose 24/7.

Ok, but wouldn't this cause a problem for the edges of the holes in the graphene being worn away by the water flowing past them?

;) Sorry!

Re:Holes? (0)

Anonymous Coward | more than 2 years ago | (#40511253)

At which point you replace the filter. Which shouldn't be that often, since graphene is tough stuff.

Re:Holes? (5, Funny)

ffflala (793437) | more than 2 years ago | (#40511171)

Occasionally some gunk gets in there but it washes away sooner or later; and nothing spends any appreciable amount of time stuck in an individual graphene hole.

She was a real hot-shooter, that bubble. I should have known she'd be trouble from the get go; she was naturally "charged" as they say when they're trying to be polite.

With her bouncing around all over the place even at room temperature, I guess I should have seen it coming. But, as will happen to palookas and wishful thinkers, my hopes and processes got the best of me. I was convinced that any trouble would wash away as soon as it cropped She didn't even say goodbye, just left a note saying she'd thought she had found a solution with me, but couldn't stand the suspension and was afraid of becoming just another precipitate.

That was three years ago. I took the tube directly to this here graphene hole; it was the closest one I could find. I've been stuck here ever since.

Re:Holes? (1)

EdIII (1114411) | more than 2 years ago | (#40511201)

Lol.

I love that video. The music reminds me of The Life Aquatic with Steve Zissou.

Re:Holes? (2)

bill_mcgonigle (4333) | more than 2 years ago | (#40511221)

not disagreeing with your assessment, but:

Gunk can get stuck in the holes and it has to be washed off, which requires a fair amount of work because I have to break the interaction between the gunk and the surface. That's your macroscopic intuition about how filters and such work.

I think people may be basing their assumptions on typical RO membranes, which are microscopic in function and do get gunked up and need to be replaced. In fact, that's next on my project list for the kitchen, after I get done wasting time on /. ;)

Re:Holes? (0)

flyneye (84093) | more than 2 years ago | (#40510977)

Let's think of disposing this too. Can't just dump concentrated sea goo back in one place. Too much goo wouldn't do.It would turn the fishies blue.
Keeping it would raise a smell, even if it had energy potential. Burning it will piss someone off. We don't utilize the potential of natural fertilizers available on land,not gonna start using Ocean Spew anytime soon.Labeling it nutritional is probably dangerous, so naturally that's what will happen.

Re:Holes? (1)

marcosdumay (620877) | more than 2 years ago | (#40511119)

Let's think of disposing this too.

Disposing of what exactly? Brine? We already to that, with very light effects on the environment. The graphene? It's not toxic, it can be safely handled and stored; burning it will release only CO2 and (a very small amount of) water.

Re:Holes? (4, Insightful)

mrchaotica (681592) | more than 2 years ago | (#40511245)

You sell it as fancy eco-friendly sea salt for $15/lb.

Re:Holes? (1)

Grishnakh (216268) | more than 2 years ago | (#40511329)

No, it'll probably drive down the price of sea salt.

BTW, sea salt is great stuff; it tastes much better than table salt (mainly because of the other constituent elements like calcium and magnesium).

Re:Holes? (3, Interesting)

Grishnakh (216268) | more than 2 years ago | (#40511299)

Oh please. For one thing, we already have desalination plants in some places dumping brine back into the sea; obviously it's not a big problem. There's a lot of water in the oceans. Secondly, the highly concentrated brine from these graphene filters could potentially be valuable for harvesting sea salt. We already have giant sea salt plants, where basically ocean water is left to dry out so we can take the salt out; between humans taking sea salt and leaving the water, and taking water and leaving the salt, I don't think there's any net effect on the oceans. And these graphene filters could make sea salt harvesting potentially more efficient.

Could you boost durability by stacking several? (1)

Anonymous Coward | more than 2 years ago | (#40510753)

I mean, you probably can't filter water through a block of carbon, but what you can do is cheat and just use individual graphene layers placed very closely together. Also, if you don't rely on the force of gravity but instead let the water enter sideways or upwards, deposits would be a smaller problem.

Re:Could you boost durability by stacking several? (2)

rickb928 (945187) | more than 2 years ago | (#40510925)

My $30 refrigerator water filter includes a 'block of carbon'. It even says so on the carton, though I sawed one open to see, and yes, a block of carbon.

Anyways, that's still too porous to be very effective compared to RO or the new RO, Graphene.

And virtually NO public water system in the U.S. relys exclusively on gravity. My birthplace pumped water up to on of two standpipes, which then used gravity to supply us water under pressure, but the pumps were needed. Even New York City pumpsm despite their supply coming from Upstate New York. At higher elevation. Friciton losses from the pipes, canals (?), and aqueucts negate that.

But a graphene filter at the bottom of a standpipe could be a gravity solution, and all you need is a solution to clearing the filter and replacing it occasionally. That seems doable.

Re:Could you boost durability by stacking several? (5, Informative)

I_am_Jack (1116205) | more than 2 years ago | (#40511401)

You can purify water with activated carbon ("purify" is highly subjective, unless a governmental authority has taken the time to define it; otherwise, it's up to the marketing department). If you want to remove chlorine and objectionable tastes and odors, a simple activated carbon cartridge works great. If you want to remove heavier VOC's (volatile organic compounds) and THM's (trihalomethanes), you can use a compressed carbon block. And you can use a 1 micron absolute carbon block if you want to do all of the above, as well as achieve five log reduction (99.999%) in Giardia and Cryptosporidium cysts, as well as removing 95% of lead in water (most lead found in water is particulate and not ionic).

Desalinating is a little more complicated than this. Currently, there are three (fairly simple) methods of desalinating water: reverse osmosis, steam (or vapor compression) distillation, and de-ionization. RO is usually the preferred method, because a commercial RO unit can purify a high volume of sea water at around 70-90% efficiency.

Steam or vapor compression distillation requires a lot of energy, leaves a massive amount of residue, and depending on mineral concentrations of the feed water, requires constant cleaning to prevent the equipment breaking down.

De-ionization requires no energy, but depending on the type of DI resins used, can quickly exhaust the filter bed, requiring regeneration, which again, doesn't require a lot of energy, but it does have a chemical cost to strip and regenerate the Cation/Anion resins.

Regardless of which method of desalination is being used, the feed water should be filtered to remove sediment and volatile organics (or post-filtration, in the case of DI).

The graphene method is essentially creating a thin film membrane like RO. If you jump past the original article, and go to Water Online, the method proposed would be actually be using a thin film scaffolding to support the nano layer of graphene. At that point, you might as well use RO, unless the actual production models (the graphene method proposed is still highly theoretical as the authors admit that consistently producing graphene with a uniform pore diameter is not practical yet) would allow greater pure water production at higher efficiencies than currently available with RO.

If you want to make ultra-pure water (say USP water-for-injection grade) you need to use a combination of all the above. What results you want will determine the method or number of steps required.

Nestle (0)

Anonymous Coward | more than 2 years ago | (#40510765)

Nestle should be all over this.
Unfortunately the would probably bury it.

Re:Nestle (1)

chill (34294) | more than 2 years ago | (#40510779)

But they would bury it in chocolate. Delicious, smooth, yummy chocolate.

Re:Nestle (1)

NormalVisual (565491) | more than 2 years ago | (#40510815)

Delicious, smooth, yummy, *salty* chocolate.

Re:Nestle (1)

redneckmother (1664119) | more than 2 years ago | (#40511237)

Delicious, smooth, yummy, *salty* chocolate BALLS. oblig.South Park Reference

Why stop at salt? (5, Interesting)

cryfreedomlove (929828) | more than 2 years ago | (#40510773)

How does this filter work on bacteria and viruses? The standard of living in the 3rd world would go up dramatically with free access to clean water.

Re:Why stop at salt? (5, Interesting)

RPGillespie (2478442) | more than 2 years ago | (#40510873)

Well considering that the holes are the size of water molecules, I think it would be safe to say that bacteria and viruses would not fit. It would be like trying to force a tennis ball through a hole in a pasta strainer.

Re:Why stop at salt? (5, Insightful)

LionKimbro (200000) | more than 2 years ago | (#40511213)

Water Molecule: 275 pico-meters

Ecoli Bacteria: 0.6 micro-meters (109,000x larger)

Rhinovirus: 30 nm (110x larger)

Re:Why stop at salt? (-1)

Anonymous Coward | more than 2 years ago | (#40510901)

Less blacks means increasing standard of living for the world.

Re:Why stop at salt? (-1, Troll)

king neckbeard (1801738) | more than 2 years ago | (#40510939)

Increasing the standard of living is an effective way of reducing population growth, so it would actually result in less blacks.

Re:Why stop at salt? (3, Insightful)

NEDHead (1651195) | more than 2 years ago | (#40510989)

Not 'less'. 'fewer'.

Re:Why stop at salt? (-1, Troll)

Anonymous Coward | more than 2 years ago | (#40510975)

Slashdot is a place where people get modded down for strictly speaking the truth, even if that's not the path of action we as a society should follow. If blacks are so poor, fewer black people can only increase the standard of living. So in conclussion, the standard of living alone isn't a good criteria to evaluate an action.

Re:Why stop at salt? (-1, Flamebait)

MightyMartian (840721) | more than 2 years ago | (#40511393)

Slashdot is a place where cowardly racist fucktards post with impunity. I hope you die of the most horrific cancer one can imagine, so that your flesh falls off in chunks and you smell like a rotting corpse, so that even your wife has to leave you because your body has become as vile and evil as your mind.

Re:Why stop at salt? (0)

Anonymous Coward | more than 2 years ago | (#40510909)

How does this filter work on bacteria and viruses? The standard of living in the 3rd world would go up dramatically with free access to clean water.

It does not kill bacteria and viruses. Moreover in some cases - if you don't clean or change filters often enough mold and bacteria will grow. Usually, you either boil the water or add an extra stage filter with UV light bulb to treat the water before it enters and exits the storage tank.

Re:Why stop at salt? (0)

Anonymous Coward | more than 2 years ago | (#40510943)

You don't have to kill them, just keep them out of the drinking water.

Besides, your extra salty-water on the other side of the filter will keep a lot down, if you're converting sea-water.

Hopefully this will also work well with a solar water-boiler just to be able to make it safer though.

Re:Why stop at salt? (1)

Anonymous Coward | more than 2 years ago | (#40511005)

And how is a bacterium or virus going to make it through a hole too small for a salt molecule?

Re:Why stop at salt? (0, Redundant)

Lumpy (12016) | more than 2 years ago | (#40511403)

This is 100% incorrect. I suggest learning about the filter before making things up.

you can already buy a filter for drinking virus laden pond water safely. This filter will be just as effective as no viruses are small as or smaller than a H2O molecule.

The way these filters work they will not have a mold or bacteria growth problem either, Please actually learn about the subject before commenting.

Re:Why stop at salt? (0)

Anonymous Coward | more than 2 years ago | (#40510983)

Because a salt molecule is already smaller than a virus by about 3 orders of magnitude. You block the salt, you block all of the nasty organisms too.
However, according to the dumbed-down article, we haven't actually managed to punch holes small enough for just the water molecules to pass through yet.

Correction: (0)

Anonymous Coward | more than 2 years ago | (#40511013)

An atom is roughly 5 orders of magnitude smaller than a virus; so on that scale a salt molecule wouldn't be significantly bigger than a single atom.

Re:Why stop at salt? (4, Interesting)

girlintraining (1395911) | more than 2 years ago | (#40511117)

The standard of living in the 3rd world would go up dramatically with free access to clean water.

There's a trend towards decreasing access to freshwater in many developed parts of the world as well. Much of the southern United States will be uninhabitable within our lifetimes if they do not secure another source of fresh water. I do not think just the '3rd world' has this problem. We will all be '3rd world' if the trend continues. And then no world... because almost all life on land depends on it.

Re:Why stop at salt? (5, Interesting)

bill_mcgonigle (4333) | more than 2 years ago | (#40511175)

Much of the southern United States will be uninhabitable within our lifetimes if they do not secure another source of fresh water

yet if you mention this to people who live there they go absolutely bonkers denial on you. I guess I'm not speaking about the small minority who will profit from doing the math.

Re:Why stop at salt? (4, Informative)

jbeach (852844) | more than 2 years ago | (#40511263)

Agreed. People can show even more denial with this than with the Peak Oil problem we're going to be facing. Not the Pentagon; they're busy making plans and releasing public papers that point out the upcoming world shortages in water AND oil. But they're a bunch of pointy-headed eco-socialists apparently.

Re:Why stop at salt? (0, Troll)

girlintraining (1395911) | more than 2 years ago | (#40511283)

yet if you mention this to people who live there they go absolutely bonkers denial on you. I guess I'm not speaking about the small minority who will profit from doing the math.

They believe suffering is good for the soul... and so, they suffer. Don't feel bad about it. It's what Jesus wants. Once they're all dead, we'll buy the land for cheap and redevelop it. In the meantime, we'll just exploit the cheap labor, and lock them into an unending life of debt and suffering... Someone has to work the salt mines. *shrugs*

Re:Why stop at salt? (0)

Anonymous Coward | more than 2 years ago | (#40511357)

Just like Peak Oil, it won't be the faucet turning off all at once. There is a lot of room for conservation in households. There's more room for conservation in agriculture than you might think. I was shocked to find that California grows rice. Rice??? In a state where the air can get dry enough some days to evaporate quite nicely, where we are already rationing??? Plainly they'll have to stop growing rice in California. People will have to get smarter about it. The coastal hills in California have streams that wash away houses in the winter, and trickle in the fall. When push comes to shove, small hydro will get pencil-whipped past all the radical green zealots. It's hard to protest when you collapse on your picket line due to dehydration.

It is a RO membrane, just a really good one (4, Informative)

vlm (69642) | more than 2 years ago | (#40510777)

Basically, the regular atomic structure of graphene means that you can create holes of any size, for example the size of a single molecule of water. Using this process scientist can desalinate saltwater 1,000 times faster than the Reverse Osmosis technique.

It is a RO membrane, just a really good one? They've described exactly how a RO membrane works. Of course this may have more "holes per sq inch" or whatever, maybe even 1000 times as many.

Re:It is a RO membrane, just a really good one (4, Insightful)

trout007 (975317) | more than 2 years ago | (#40510829)

This is only a guess by RO filters have two things that take power. They require a high pressure differential across the membrane which makes for expensive pumps, piping and electric bills. Also they have a lot of bypass water which wastes energy by making you bring it up to pressure and then just dump it out.

If this membrane requires less pressure and less bypass it will significantly reduce both the capital costs and operating costs of such a system.

Re:It is a RO membrane, just a really good one (5, Informative)

qvatch (576224) | more than 2 years ago | (#40511017)

The abstract: "We show that nanometer-scale pores in single-layer freestanding graphene can effectively filter NaCl salt from water. Using classical molecular dynamics, we report the desalination performance of such membranes as a function of pore size, chemical functionalization, and applied pressure. Our results indicate that the membrane’s ability to prevent the salt passage depends critically on pore diameter with adequately sized pores allowing for water flow while blocking ions. Further, an investigation into the role of chemical functional groups bonded to the edges of graphene pores suggests that commonly occurring hydroxyl groups can roughly double the water flux thanks to their hydrophilic character. The increase in water flux comes at the expense of less consistent salt rejection performance, which we attribute to the ability of hydroxyl functional groups to substitute for water molecules in the hydration shell of the ions. Overall, our results indicate that the water permeability of this material is several orders of magnitude higher than conventional reverse osmosis membranes, and that nanoporous graphene may have a valuable role to play for water purification." Emphasis added for why, and the introduced problem

Re:It is a RO membrane, just a really good one (2)

phme (1501991) | more than 2 years ago | (#40510835)

From phys.org [phys.org] :

In contrast to RO, which uses high pressure to slowly push water molecules (but not salt ions) through a porous membrane, nanoporous materials work under lower pressures and provide well-defined channels that can filter salt water at a faster rate than RO membranes.
However, this is the first time that scientists have explored the potential role of nanoporous graphene as a filter for water desalination. Single-layer graphene, which is just one carbon atom thick, is the ultimate thin membrane, making it advantageous for water desalination since water flux across a membrane scales inversely with the membrane’s thickness.
[...]
The scientists explain that there are two main challenges facing the use of nanoporous graphene for desalination purposes. One is achieving a narrow pore size distribution, although rapid experimental progress in synthesizing highly ordered porous graphene suggests that this may soon be feasible. The other challenge is mechanical stability under applied pressure, which could be achieved using a thin-film support layer such as that used in RO materials.

Re:It is a RO membrane, just a really good one (1)

fermion (181285) | more than 2 years ago | (#40511375)

It is not an RO membrane which is why it may be difficult to make it work. In RO the majority of the filtrand is automatically washed away as only a small amount of the water makes it through the filter. So, for instance, if you have an RO filter installed in your house, you may use 100 gallons of filtered water, but will be charged for 1000 gallons, as this is the amount that flows through the filter. The disadvantage is that the water must be pressurized. This is not a huge expense as one can buy a gallon of of RO water for a quarter, and on industrial scales it is quite cheap if you are using surface water. Of course you are going to increase the contamination levels of the surface water over time as you filter out small amount of clean water.

In this technology, the pores of the Graphene are such that only the water molecule will pass through when water is flowed through the filter at normal pressures. The practical question I have, since this is not like a carbon filter, but a single layer of Graphene, is how are they going to remove the filtrand to keep the clean. The technical question that the researches have to solve is how to make the graphene, and how to functionalize the pores so that water is encouraged to flow through the hole and impurities are encouraged to not block the pores.

This seems like a relatively early stage idea with no prototype, and little idea of if it will be marketable.

Forget about how long it takes, what's the ENERGY (5, Insightful)

Bruce Perens (3872) | more than 2 years ago | (#40510781)

If they've found a way to desalinate water with much less energy, practically, that's huge.

Re:Forget about how long it takes, what's the ENER (1)

drdrgivemethenews (1525877) | more than 2 years ago | (#40510997)

Given that energy is power exerted over time, making something 1000 times faster using the same energy means using 1000 times the power. Making it 1000 times faster using the same power would use 1/1000th of the energy.

-------

All notions of cause and effect are merely assertions of faith in statistics.

Symposium at College of William & Mary (0)

Anonymous Coward | more than 2 years ago | (#40511057)

If others have found a way to abundance of energy, we won't need graphene to desalinate water.

That wouldn't be huge, that would be disruptive.

1 - 3 July at College of William & Mary; International Low Energy Nuclear Reactions Symposium (ILENRS-12)

Re:Symposium at College of William & Mary (2)

bill_mcgonigle (4333) | more than 2 years ago | (#40511203)

If others have found a way to abundance of energy, we won't need graphene to desalinate water.

You'd still want both. If you need a given volume of water, you either need a process that's 1000x faster or 1000x the infrastructure. Infrastructure isn't cheap, no matter how much energy you have.

That wouldn't be huge, that would be disruptive.

Perhaps you've noticed the power structure doing less than the minimum it can excuse as valid in this area?

1 - 3 July at College of William & Mary; International Low Energy Nuclear Reactions Symposium (ILENRS-12)

cool, wish I could be there. I hope they choose to upload videos, for the good of mankind.

Re:Forget about how long it takes, what's the ENER (1)

marcosdumay (620877) | more than 2 years ago | (#40511145)

Ok, that almost summarizes it.

The only thing missing is that the article implies that nobody have actualy created it. But there aren't enough details to be certain of that. I'd say, "they found, or somebody found, or there are people looking for it, or they think people could look for it".

Re:Forget about how long it takes, what's the ENER (5, Insightful)

imjustmatthew (1164609) | more than 2 years ago | (#40511311)

Figure 8 on Page 6 of the actual paper [mit.edu] shows what they're measuring. They're comparing filter materials by Salt rejection % vs Water permeability measured in L/cm2/day/MPa. That unit incorporates all the energy-efficeny goodness you want in a filter without looking at what pump technology is actually used to provide the energy input. It says that more filtered water (L) per square centimeter of filter (/cm2) per day (/day) per MegaPascal of pressure (/MPa, the energy input) is more good. Assuming any particular pump technology would give you a number for MPa/MJ that you could apply, but it doesn't help you understadn the performance of the filter itself. The figure for improvement vs existing technology they actually give is 2-3 orders of magnitude (100-1000x) so TFS is taking the optimistic side.

The bottom line is that this has a huge potential but is still a ways from practical application.

Re:Forget about how long it takes, what's the ENER (1)

Bruce Perens (3872) | more than 2 years ago | (#40511365)

Yes, there's a lot of materials science to be done before this is practical, and there may be unforeseen complications.

But if this works, it would be nice to have:

  • A practical filter for drinking saltwater through a straw.
  • Some really big changes in California and places with similar water issues.

Re:Forget about how long it takes, what's the ENER (1)

DaveGod (703167) | more than 2 years ago | (#40511379)

If they've found a way to desalinate water with much less energy, practically, that's huge.

TFA isn't wholly explicit but it actually talks about "efficiency" rather than "faster" as per the submission:

According to researchers at MIT, graphene could also increase the efficicency of desalination by two or three orders of magnitude [...] while you can remove the salt from the water, the current methods of doing so are laborious and expensive. Graphene stands to change all that by essentially serving as the world’s most awesomely efficient filter. If you can increase the efficiency of desalination by two or three orders of magnitude (that is to say, make it 100 to 1,000 times more efficient) desalination suddenly becomes way more attractive as a way to obtain drinking water.

Though following TFA's source link to Water Online [wateronline.com] we come back to "2-3 orders of magnitude faster" and then reference to energy and cost:

In a new study, two materials scientists from MIT have shown in simulations that nanoporous graphene can filter salt from water at a rate that is 2-3 orders of magnitude faster than today’s best commercial desalination technology, reverse osmosis (RO). The researchers predict that graphene’s superior water permeability could lead to desalination techniques that require less energy and use smaller modules than RO technology, at a cost that will depend on future improvements in graphene fabrication methods.

To me that implies subby read that source article, which is a rather better article, leading me to suspect "anonymous reader" subby is from http://www.geekosystem.com/ [geekosystem.com] It does kind of bug me a little when websites find someone else's story, don't contribute anything then go around plugging it like it's their scoop.

And BTW that Water Online source itself is lifted verbatim (stated as being with permission) from Phys.org [phys.org] .

video cards (-1)

Anonymous Coward | more than 2 years ago | (#40510783)

only losers have $500 video cards, lol losers

Re:video cards (-1)

Anonymous Coward | more than 2 years ago | (#40511021)

u jelly?

Re:video cards (0)

Anonymous Coward | more than 2 years ago | (#40511419)

Still pissy that you live in your mom's basement? some day you will be able to save enough to pay a hooker to let you actually touch a boob.

Wow! They'd have enough salt to last forever. (3, Funny)

trout007 (975317) | more than 2 years ago | (#40510793)

God I loved "Top Secret"

Filtering abilities of graphene membranes (4, Funny)

K. S. Kyosuke (729550) | more than 2 years ago | (#40510803)

I just wonder if a graphene membrane could filter out the words "awesomely", "incredibly" and "super" from awesomely incredibly super texts, leaving only texts. *That* would be quite useful.

Just what we need, clean drinking water (1)

justfred (63412) | more than 2 years ago | (#40510813)

This sounds like it could be revolutionary - lack of fresh or clean water is one of the world's biggest problems. I'm assuming pathogens are larger than a molecule of water? Wonder what the cost would be, if it would be cheap enough to just churn out sheets of the stuff, or custom-made filters. The biggest problems aside from production would be clogging/cleaning and accidental contamination of the output stream.

The real link (5, Informative)

OzPeter (195038) | more than 2 years ago | (#40510817)

The TFA is just a BS article that says nothing.
 
A better link (and is in the TFA) is Nanoporous Graphene Could Outperform Best Commercial Water Desalination Techniques [wateronline.com]
 
However that references Nanoporous graphene could outperform best commercial water desalination techniques [phys.org]
 
Now we finally we get to the actual link Water Desalination across Nanoporous Graphene [acs.org] (which unfortunately you need to have the right credentials to see - which I don't)
 
How come I can follow those links and the TFS can't?

Re:The real link (-1)

Anonymous Coward | more than 2 years ago | (#40510861)

You do know that the "T" in "TFA" stands for "the" don't you?

The TFA

in the TFA

You must work for the Department of Redundancy Department, surely?

Re:The real link (1)

OzPeter (195038) | more than 2 years ago | (#40510919)

You must work for the Department of Redundancy Department, surely?

Don't call me Surely

Re:The real link (5, Informative)

notjustchalk (1743368) | more than 2 years ago | (#40510877)

Here's the real article (AFAIK) from The Grossman Group @ MIT, no need for credentials.
Water Desalination across Nanoporous Graphene (Warning PDF Link): http://zeppola.mit.edu/pubs/nl3012853.pdf [mit.edu]

The main site for the Grossman Group is also pretty fascinating: http://zeppola.mit.edu/ [mit.edu]

Um, no. (1)

caffeinated_bunsen (179721) | more than 2 years ago | (#40510837)

Thank you, anonymous reader, for a confused summary of an idiotic blog post about a moderately dumbed-down article about an interesting article.

What they're talking about is reverse osmosis, and there's no way to make it two or three orders of magnitude more efficient. Commercial systems already hit 30% to 60% of the thermodynamic limit for energy efficiency; all graphene offers in this case is a way to increase the speed, decrease the filter size, or reduce the unnecessarily wasted energy. There's still no getting around that darned osmotic pressure.

Re:Um, no. (0)

Anonymous Coward | more than 2 years ago | (#40510883)

Thank you, anonymous reader, for a confused summary of an idiotic blog post about a moderately dumbed-down article about an interesting article.

Is that like the little kids' game where they play telephone with paper cups and string?

Re:Um, no. (1)

phme (1501991) | more than 2 years ago | (#40510929)

I know nothing of the subject, so I actually bothered reading a more decent summary [phys.org] of the initial article, and some definition of reverse osmosis [wikipedia.org] .
From wikipedia:

Reverse osmosis (RO) is a membrane-technology filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane. The result is that the solute is retained on the pressurized side of the membrane and the pure solvent is allowed to pass to the other side.

and from phys.org:

In contrast to RO, which uses high pressure to slowly push water molecules (but not salt ions) through a porous membrane, nanoporous materials work under lower pressures and provide well-defined channels that can filter salt water at a faster rate than RO membranes.

And same article displays a chart showing water permability of about 100 L/cm/day/MPa for graphene in contrast to 0.5 for high-flux RO.

Re:Um, no. (3, Informative)

caffeinated_bunsen (179721) | more than 2 years ago | (#40511095)

I think they're abusing the terminology a bit, using "RO" to refer to reverse osmosis conducted with existing membrane technologies. The point at issue is that thermodynamics demands that a certain amount of energy be expended in order to reduce the entropy of a homogeneous salt solution by separating it into pure (or at least low-salinity) water and high-salinity leftovers. This is totally independent of the means by which the molecules are separated. In reverse osmosis, that manifests as a minimum pressure necessary to force salt water through any selectively permeable membrane.

Practical RO systems operate with a pressure drop (and therefore energy consumption per unit volume) that's double or triple the osmotic pressure, in order to achieve useful flow rates across thick membranes with relatively low pore densities. A better filter would allow that excess pressure to be reduced, but can't do anything about the cost of reducing the entropy.

trifecta (4, Funny)

tverbeek (457094) | more than 2 years ago | (#40510843)

Once we figure out how to make nanobots out of stem cells and graphene, every problem known to humanity will be solved!

Re:trifecta (1)

K. S. Kyosuke (729550) | more than 2 years ago | (#40511163)

Once we figure out how to make nanobots out of stem cells and graphene, every problem known to humanity will be solved!

What about the as-of-yet unsolved problem of "Where shall we have lunch?"

Re:trifecta (1)

barfy (256323) | more than 2 years ago | (#40511307)

Only if it improved battery life by 10x...

Incredibly precise sieve? (1)

NotSoHeavyD3 (1400425) | more than 2 years ago | (#40510891)

Hey, doesn't that mean that there's another way to produce 100% pure ethanol? http://en.wikipedia.org/wiki/Ethanol_purification#Molecular_sieves [wikipedia.org]

Of courswe they wouldn't (1, Informative)

Kupfernigk (1190345) | more than 2 years ago | (#40510955)

"Troll" is nothing to do with fantasy monsters and everything to do with fishing. A troll is someone who floats a line with yummy bait across a discussion board and waits to see who bites, having failed to notice that the grub or worm is on a hook.

These people who didn't discover the Internet till this century...kindly remove yourself from my area of cultivated graminoids.

Re:Incredibly precise sieve? (0)

Anonymous Coward | more than 2 years ago | (#40511351)

>doesn't that mean that there's another way to produce 100% pure ethanol? ...from methylated spirits? :D

Other materials (1)

king neckbeard (1801738) | more than 2 years ago | (#40510897)

While I'm sure this process would be useful by itself, I wonder if the same or similar techniques could be used for purifying other materials. For example, maybe new levels of purity in various fuels.

The original paper (4, Informative)

jmichaelg (148257) | more than 2 years ago | (#40510907)

Here's a link to the original paper on Grossman's website. [mit.edu]

Re:The original paper (4, Informative)

slug.slug (1941670) | more than 2 years ago | (#40511101)

Thanks for the link. I skimmed through the paper and realized that this is a *theoretical simulation* of the process using molecular dynamics, so although with promising predictions, please give me a call when they actually have a working device.

Old idea is old. (0)

Anonymous Coward | more than 2 years ago | (#40510921)

Old idea is old.

Energy & Storage (0)

Anonymous Coward | more than 2 years ago | (#40510951)

How much energy is consumed with this form of filtration? Then we need a way to handle the salt and calcium that is left behind. Dumping that by-product back into the ocean is not a reasonable idea. Perhaps we could find some old salt mines and pack the by-products down into those huge old mines. Then we would have to consider the energy required to store all of that waste.
              I feel like science theory seems to be easy top come by but useful, applied, science that actually helps man kind seems to be rare and hard to put into play/

Re:Energy & Storage (1)

marcosdumay (620877) | more than 2 years ago | (#40511209)

You are the secon one I see here claimming that we can't dump salt on the ocean. WTF? Of course we can dump salt on the ocean. What do you think we'll do with the fresh water after we use it? Those things cancel each other.

Re:Energy & Storage (0)

Anonymous Coward | more than 2 years ago | (#40511325)

Depends on the source of the salt water. If you use a previously too salty aquifer you add salt (and water) to the oceans. If you take it from the ocean then the sums in the cycle are unchanged.

Re:Energy & Storage (1)

shentino (1139071) | more than 2 years ago | (#40511321)

Sell it as sea salt.

Here's a similar working prototype (1)

SeanDS (1039000) | more than 2 years ago | (#40511147)

Michael Pritchard presented a filter device at TED in 2009 which used a similar concept to filter water. The video explains why bacteria and viruses are filtered out, and he demonstrates the process and drinks the resulting filtered water (taken from a sewage bath he concocts). Perhaps graphene's physical strength will make it a more sturdy water filter, which would be a particularly important criteria for use in the third world, but there is at least already a working prototype using a non-graphene material. http://www.ted.com/talks/michael_pritchard_invents_a_water_filter.html [ted.com]

Uhmm....I sense a problem with scale. (4, Interesting)

mark-t (151149) | more than 2 years ago | (#40511193)

Water molecule size, roughly 0.340 nm
Salt molecule size, roughly 0.500 nm
Graphene molecule size, roughly 0.142 nm
Difference in size between water and salt molecule, roughly 0.160 nm
The difference in size between water and salt is just barely more than the size of a single graphene molecule, so that leaves absolutely *NO* margin for error when designing the graphene sheet with those holes.

This might very well have already been proven to really work... but I expect it would be extremely cost ineffective at larger scales owing to the consistent and extremely accurate precision that would be needed when trying to do this at a macroscopic scale.

Re:Uhmm....I sense a problem with scale. (5, Informative)

caffeinated_bunsen (179721) | more than 2 years ago | (#40511305)

That's not as big a problem as you'd think. In solution, you don't have molecules of NaCl; you have dissociated ions of Na+ and Cl-, each of which is surrounded by a cluster of rather tightly-bound water molecules. Those clusters are much larger than bare ions or single water molecules, so there's a fair range of pore sizes that will separate the ions from the water.

Is there anything graphene CAN'T do? (0)

Anonymous Coward | more than 2 years ago | (#40511279)

I'm going to start putting it in my coffee.

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