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New Process For Nanoscale Filtration Holds Promise of Cheap, Clean Water 116

Posted by Soulskill
from the fighting-the-evil-oceans dept.
New submitter Spinnakker writes "Lockheed Martin, traditionally known for its development of military systems and aircraft, has developed a process for perforating graphene (carbon sheets only one atom thick) that could potentially reduce the energy required for desalination by two orders of magnitude. The process tailors the hole size to the molecules being separated. In the case of desalination, one would create holes in the graphene large enough to allow water to pass but small enough to block the salt molecules. The advantage to using graphene comes from how extremely thin the material is compared to traditional filters. The thinner the filter, the less energy is required to facilitate reverse osmosis."
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New Process For Nanoscale Filtration Holds Promise of Cheap, Clean Water

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  • Holy moly (Score:5, Insightful)

    by i kan reed (749298) on Friday March 15, 2013 @02:53PM (#43185647) Homepage Journal

    I remember when this theoretical technology was proposed about a year ago, and figured it would be a decade before they could actually do it.
    Cheap desalinization and filtration would mean an end to one of the biggest world health problems(safe drinking water), and could improve world-wide standards of living dramatically.

    • Re: (Score:3, Funny)

      by fustakrakich (1673220)

      It's very hard to keep prices up and maintain austerity measures if fresh, clean water becomes more abundant. Desalination seems like such a waste when we can collect, harvest, and distribute rain water. But low profit margins will keep that from happening. Making war and stealing other peoples' water is the market solution.

      • by alen (225700)

        we already do collect rain water

        upstate NY the rain falls into lakes and rivers and then into the NYC water system

        i don't think its feasible collecting rain water straight from the sky though

        • Re:Holy moly (Score:5, Informative)

          by Ol Biscuitbarrel (1859702) on Friday March 15, 2013 @03:42PM (#43186069)

          i don't think its feasible collecting rain water straight from the sky though

          Sure it is, people have been doing it for millenia: Brief Outline of the History of Rainwater Catchment Technologies [ernet.in]

          Archaeologists found a sophisticatedrainwatercollection and storage system on the island of Crete while working on the reconstruction of the Palace of Knossos (1700 B.C.). However, with the development of building construction based on new materials such as lime and burnt clay bricks, new construction techniques like arches and domes developed. The ancient Romans became masters inrainwaterharvesting and the construction ofreservoirs. It was this new technique of building closed cisterns, and at the same time the urbanization within the Roman Empire around the Mediterranean, which resulted in the development of arainwatercatchment culture at all those places where water resources were limited. This is why oldrainwatercisterns are to be found on the islands of Capri and Malta and at places of historical interest in Spain and Turkey, in the Lebanon and on the island of Sicily.

          Plenty of research is being conducted on modern approaches to rainwater harvesting. In the developed world these often come into conflict with environmental regulations regarding water quality, and in general there's a surfeit of water from other sources that is ran through central filtration facilities so no great press is on to tap rainwater as a major source. It's something popular with people who are interested in green tech and the like.

          • by fazookus (770354) *
            The problem with rainwater harvesting that most of the worlds potable water already comes from rainwater... in anything approaching a largish scale you're going to be in conflict with river basins and the like and grabbing rain destined for forests, farm animals and crops.. The advantage of desalination is that you let nature harvest the rainwater and concentrate it for you and then just process that.
            • by rohan972 (880586)
              Most water people use ends up in the drain, being treated and returned to the system. Bringing in desalinated water doesn't preserve the natural water levels in that area it adds to it. Desalination and centralized distribution also has infrastructure and energy costs that local rain harvesting doesn't and then there's the problem of what to do with the salt.
        • by Anonymous Coward

          we already do collect rain water

          gp never said we didn't

        • by Anonymous Coward

          Here in Australia most of the households use rain water, I'm not even connected to the town water (and I'n not a threehugger...).
          The idea initially sounded weird (I'm from Europe), but it works fine and the quality is excellent, without fluoride and other craps.

      • by Anonymous Coward

        I bet you are a lot of fun at parties:

        "The punch is probably poisoned".

        "You are just contributing to Big Liquor".

        "I bet none of these girls really like me. They're just after my money"

        "Did you know that Halliburton owns Frito Lays?"

      • by reboot246 (623534)

        Making war and stealing other peoples' water is the market solution.

        Actually, very few wars have been fought over water.
        "Scientists at International Water Management Institute and Oregon State University have recently found that water conflicts are in the minority of issues concerning water use with hundreds of treaties in place guiding benevolent use of water resources between nations. Water conflicts tend to arise as an outcome of other social issues."

    • The problem with existing home RO is that the pressure available is low resulting in a lot of wasted water. Efficiency is maybe 15%. This may be a big help in that regard.

      The other limitation with membranes is they are not sufficient for sterilization. Holes in the membranes plus the lack of residual action means additional treatment is needed downstream of the filter. This is not likely to address that issue.

      • Which viruses or bacteria are you worried about that are smaller than salt ions?
      • Re:Holy moly (Score:4, Informative)

        by Zeromous (668365) on Friday March 15, 2013 @03:19PM (#43185861) Homepage

        No bacteria would pass though due to size, so coagulation not necessary. Chlorination also not necessary.

        So what does that leave, purification of certain compounds which happen to be smaller than H2O? (likely a mild chemical treatment process judging by other filtration techniques.) Since this is a desalination filter process seems safe to assume anything above Ng on the perdioc table would not pass through ( I am not a chemist by trade so please correct me if I am wrong). This leaves H He Li Be Bo C N O Fl Ne to be worried about from a chemical standpoint after filtration.

        So what really is left after passing through graphene?

        • by Zeromous (668365)

          Ach, anything above Ne* I mean (Boron just B, also Flourine is just F). Told you I wasn't a chemist, but not bad from memory.

        • by Anonymous Coward

          In practice, a fraction of the living bacteria can and do pass through RO membranes through minor imperfections, or bypass the membrane entirely through tiny leaks in surrounding seals. Thus, complete RO systems may include additional water treatment stages that use ultraviolet light or ozone to prevent microbiological contamination.

          wikipedia

        • Re:Holy moly (Score:4, Informative)

          by Anonymous Coward on Friday March 15, 2013 @05:50PM (#43187061)

          what does that leave, purification of certain compounds which happen to be smaller than H2O. ... This leaves H He Li Be Bo C N O Fl Ne

          He & Ne aren't a problem - 1) they're a gas, and He, at least, is sparingly soluble in water, so it'll all bubble off. 2) They're as inert as they get, so wouldn't make much of a difference even if they were in the water.

          C N O - Aren't found as mono-atomic atoms. Will always be in larger molecules, which for the most part are larger than water.

          H Li Be B F - Found as monoatomic species, but only as ions. With ions you always get a shell of hydration around them, and it's a significant amount of work to strip that away. Effectively, you don't have a Li+ on its own, you have a Li+(H2O)x complex, which by necessity will be bigger than a single water molecule

          The only thing you'd be worried about are small, neutral molecules. Something like methane might be a problem, but if you have methane in your source water, you probably know it, and will have some other pre-treatment to deal with it specially.

          • The only times methane in the water is a problem is when you burp while smoking or when the glass gets knocked out of your hand due to a gas bubble going through the water tap.

      • by iggymanz (596061)

        downstream treatment can be very simple though, appropriate filter, heating to high enough temp for appropriate time but without boiling, etc.

      • by pchimp (767649)
        As others have mentioned, with pores of this size (even with the defects or 'holes' in the membrane) the bigger problem is biofouling -- bacteria, organisms, proteins... any kind of macromolecular junk may quickly clog the pores. Nevertheless, this is exciting news; affordable desalination is sure to be a critical technology sooner than we like.
      • by rtb61 (674572)

        Downstream is truly the wrong word. The highest cost of desalination is, everywhere you want to use the water is going to be 'upstream' from it source. Most fresh water is used downstream from it's source less or no expensive pumping. Getting that water uphill is the real cost, pumping tons and tons of it, many kilometres inland and many hundreds of even thousands of metres uphill is the real cost problem. Cheap energy produces cheap water and low cost nuclear is still the best interim goal to producing lo

    • Re:Holy moly (Score:5, Informative)

      by interkin3tic (1469267) on Friday March 15, 2013 @03:53PM (#43186185)
      Yes, but we still need to figure out the other half of the problem of desalination, which is what to do with the high-salt brine. If you get 50% efficiency, as much water as you get out, you'll get out wastewater with 200% salt in it. In large volumes, you obviously can't store it or evaporate it off fast enough. Dumping it into the ocean will kill anything near the exhaust. And then there's still the problem of piping the water to cities.

      It makes more sense to use this to filter out municipal waste water and re-use it for drinking water. It's right there where you need it, it's got less junk to get out than seawater, and there is less byproduct. The only problem with that is people don't like the idea of drinking their own sewage, even if it has been filtered well.

      Not to be a wet graphene blanket: this is a very good thing, you're absolutely right that it will improve the standard of living worldwide if it pans out, and we do need better filtration technology. Just that we shouldn't forget the ecological concerns.
      • by Anonymous Coward

        1. put it back into the ocean
        2. put it back into the ocean?
        3. how about try to read the above again.

        How difficult is it to actually think these days? You don't dump it with 2x salt contents. You dump it at 5% higher salt content or 1% higher salt content or whatever. Make a long pipe 2km long and dump it there.

        What's the problem?

        And please don't say "how you can do that when process outlet is 200+% salt content of input".

        But if you really don't want to dump it back in, you can

        1. make sea salt from i

      • by Tailhook (98486)

        we shouldn't forget the ecological concerns.

        Like that's going to happen.

        We could flood the planet with the bodily fluids of armchair ecologists bitching about stuff using their Chinese computer hardware.

      • by kqc7011 (525426)
        You just keep diluting it with seawater until it reaches the level of salinity that is acceptable. Maybe even start the dilution at the outflow of a sewage treatment plant, where treated, fresh water is introduced into the ocean. That way you stop killing organisms that cannot handle the freshwater. About every city that has it sewage plant outflows going into a ocean creates dead zones.
      • Ummmm.... the ocean is big, really big, and whatever water a major city needs is a small consideration compared to evaporation. You could tap a supply for all of south Florida from a single point and still dilute it to harmless levels just by mixing your 200% brine solution with 10 parts of straight seawater before discharge. I suspect industrial scale desalination would discharge much more dilute brine than 200%, unless they were attempting to also harvest sea salts, anyway...

    • by radtea (464814)

      I remember when this theoretical technology was proposed about a year ago, and figured it would be a decade before they could actually do it.

      It would be fascinating to troll through the /. archives and find out what fraction of things that were predicted to come to market in timescale X actually did so. XKCD aside, I don't think this question has ever been properly addressed.

    • by tibit (1762298)

      I'd like to know, though, if it has any applications to dialysis. We really need an artificial kidney. For those who don't know how it works: when you're on dialysis, they only dialyse you enough to survive, not enough to feel like normal people feel. People on dialysis are permanently tired and feel sick, pretty much. There was a study where they decided to find out what it'd take and they dialyzed "the heck" out of their subjects -- running them 7 days a week for 8 or more hours IIRC. And guess what: that

  • by Anonymous Coward

    How soon before I can pee into a Mr. Coffee and get iced tea?

    captcha: profound

  • by H3lldr0p (40304) on Friday March 15, 2013 @03:15PM (#43185831) Homepage

    I thought part of the problem with current desalination techniques was that it removed all of the salts making us have to go back and re-add a bunch of phosphates and whatnot that are found in fresh water sources and are somewhat expected/required by our and plant's biological functions. That is, we were making the water too pure to be used without additional processing. This sounds like that taken the next level, so how much more efficient can it really be if the process requires even more post-processing to make it usable?

    • Re:Wait a moment (Score:4, Interesting)

      by asm2750 (1124425) on Friday March 15, 2013 @08:02PM (#43187861)
      The issue with normal filtration is you need to replace the filter media after so many gallons. The issue with normal desalination is you need a lot of energy to purify the water.

      Yes you need to re-add minerals when you use this new filter for watering plants and properly hydrating the human body, but think about it. With this invention you get a filter that will pretty much last forever with no degradation as long as it is maintained properly, and you can get fresh water from the sea and toxic sources without having to use up a ton of energy and money. In the end this idea is win-win, just make sure to include the trace minerals before drinking.
      • by soundguy (415780)
        So you're saying ... plants crave electrolytes?
        • by asm2750 (1124425)
          Well magnesium, calcium, and potassium are electrolytes and plants need for them to grow. Distilled water given to plants and even humans in large quantities is very unhealthy. Spring water has these minerals and sodium in small amounts. Since this filter would eliminate these helpful minerals along with all other molecules that are toxic leaving only 100% pure H2O the minerals would need to be re-added. Also, Brawndo is pretty bad stuff like most energy drinks are. Unless you are into killing your kidneys
  • Very similar article [slashdot.org] was published half a year ago. Is there something new now?
    • Re: (Score:3, Insightful)

      by Anonymous Coward

      Very similar article [slashdot.org] was published half a year ago. Is there something new now?

      It's gone from "A group of MIT researchers" to "Lockheed Martin", the latter of which could actually make it commercially available.

  • by drmaxx (692834) on Friday March 15, 2013 @03:18PM (#43185849)
    Considering that the theoretical minimal energy requirement for seawater desalination is approx. 0.75 kWh/m3 and current RO technology can be as low as 1.5 to 2 kWh/m3 (+ an other 2 kWh/m3 to pretreat the seawater) then I am really wondering how they will gain two orders of magnitude less energy? Can anybody enlighten us about that?
    • Where's that energy currently coming from? I know nothing about desalination, but maybe better filters allow for purely gravity-fed tanks rather than some pressurized or multi-passed treatment system?

      • by Thud457 (234763)

        Where's that energy currently coming from?

        Casimir forces.

      • Unless you're working in Death Valley or the Dead Sea region, gravity-fed tanks are going to have to provide the same energy input. And if you are in one of those places, you'll have to transport it uphill at some point.
  • If this turns out to be as good as it sounds, the financial and social impacts will be staggering.

  • I had an under-the-sink reverse osmosis system (Ametek, no longer in business) more than 20 years ago. I bought it for some of the plants I was growing at the time (insectivores, epiphytes, etc.), but then I discovered that *I* liked the taste of pure water myself and my usage doubled. Those damned RO membrane cartridges were quite expensive, and I eventually stopped using it. It would be nice to see the technique revamped with graphene if it can lower the cost in general (since home RO never used electr

    • by volmtech (769154)
      A new GE unit cost less than $200. The membrane last 5 years and cost less than $50. The conditioning filters cost $40 and last 6 months. Well worth it.
      • by macraig (621737)

        Even that is considerably cheaper than in years/decades past. Last I checked they were $75 and lasted at most two years.

        • by volmtech (769154)
          I use well water and my first one lasted over five years. Chlorinated water will reduce the life of the membrane.
  • by wanfuse123 (2860713) on Friday March 15, 2013 @03:55PM (#43186211)
    We have been polluting the water ever since the industrial age began and draining the water supply at the same time. Aquifers are getting depleted, its going to become an expensive problem. It is good to see this technology finally come about . It should help us bring water to arid lands. They say that with global warming it isn't the heat that is going to affect the plant life but the lack of water supply. It is an expensive proposition however to lay thousands of miles of pipe. But perhaps it will become cheap enough to take and desalinate water and fill up major rivers so that natural distribution can be restored. It would take a lot of energy to do it but with the two orders of magnitude cheaper maybe it would be cost effective? I would also suggest that we stop polluting the water with all the plastics and use it to recycle. We produce 37,000,000 tons of plastic each year that ends up in landfills and in the water. We could convert this into fuel energy. I have done a cost analysis on the energy from plastic recycling [rawcell.com].
    • But perhaps it will become cheap enough to take and desalinate water and fill up major rivers so that natural distribution can be restored. It would take a lot of energy to do it but with the two orders of magnitude cheaper maybe it would be cost effective?

      So, as a practical matter, major rivers tend to run downhill - that is, the lowest end of the river tends to be at sea level, and the highest end at a significantly higher altitude (and often thousands of miles away). As they say, "Gravity sucks". So "fill up major rivers" involves, first, the energy necessary to desalinate the water, then you get to build a pipeline to the upper end of the river 1000 miles away, and then you can fill the river.

      As an example, New Orleans might not be very happy with the

      • Might as well convert the water into mist and throw it into the sky and let the wind move it around. The energy required to pump billions of gallons uphill is significant.
      • Lake Huron is 577 ft (176 m) above sealevel, Superior is 600 ft (180 m) not 2000 ft.

    • I've always though that plastics were a by-product of petroleum fuel - all this cheap plastic furniture is basically cast-off from the fractioning process, sure it could be used as fuel, but why not just sell it cheap to Little Tykes to make disposable backyard junk?

    • It is an expensive proposition however to lay thousands of miles of pipe.

      I take it'll be cheaper than to lay thousands of miles of oil pipe.

  • by Anonymous Coward

    so after we've got these water chips, stimpacks, we setup the vaults and wait out the inveitable nuclear winter.
    so who'll thinks they'll be a vault dweller? and would you be willing to venture out for a new chip?

  • by sp332 (781207) on Friday March 15, 2013 @06:49PM (#43187469)

    Salt is a crystal formed by ionic bonds, there's no such thing as a salt molecule. They must be making holes small enough for a single sodium ion. Not sure why they need to tailor the holes for each chemical, though. Just make them a bit bigger than water molecules, right? Than I guess a second filter that's a bit smaller, to remove contaminants that are smaller...

    • by fljmayer (985663)
      Actually I am wondering why an Na or Cl ion would be smaller than a water molecule with 3 atoms. Are they dragging polarized water molecules with them that would prevent them from passing through holes that are small enough for water? This is bit vague so far.
      • by Anonymous Coward

        Actually I am wondering why an Na or Cl ion would be smaller than a water molecule with 3 atoms.

        Na: 3 electron shells.
        Cl: 3 electron shells.
        O: 2 electron shells.
        H: 1 electron shell.

  • by Anonymous Coward

    Each hole also has a Maxwell's demon standing guard.

  • So they're going to make water filters out of material whose fragments can be so small as to pass through the blood-brain barrier - what could possibly go wrong?

    Once upon a time, asbestos was also considered a miraculous futuristic material with seemingly near limitless applications.

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