Technology Review - Published By MIT
Advertisement
« Back 1 [2]

Monday, June 12, 2006

Cheap Drinking Water from the Ocean

Continued from page 1

By Aditi Risbud
smaller text tool iconmedium text tool iconlarger text tool icon

Holt estimates that these membranes could be brought to market within the next five to ten years. "The challenge is to scale up so we can produce usable amounts of these membrane materials for desalination, or gas separation, the other high-impact application for these membranes," he says, adding that the fabrication process is "inherently scalable."

Eventually, the membranes could be adapted for a variety of applications, ranging from pharmaceuticals to the food industry, where they could be used to separate sugars, for example, says co-author Olgica Bakajin, a physicist at LLNL. "Practically, the next step is figuring out how to take a general concept and modify it to a specific application," Bakajin says.

"There are many studies that one can imagine to build upon this study," says Northwestern's Ruoff. "Our understanding of molecular processes will be helped by experiments of this type. There are interesting possibilities for nanofluidic applications, such as in nanoelectromechanical systems and in 'smart' switching [on and off] of the flow through such small channels."
« Back 1 [2]

Comments

  • Dialysis & Desalination
    Guest (Colin) on 06/12/2006 at 12:00 AM
    Posts:
    1
    Google the terms "carbon nanotube membrane dialysis". Many hits. Good info. Desalination and dialysis have much in common. Cheap water and improved health. Cheers.
    Rate this comment: 12345
    • LLNL
      Guest (Debra) on 06/13/2006 at 12:00 AM
      Posts:
      1
      How does one collaborate with LLNL the new "carbon nantube membrane dialysis" is the discovery we've been waiting for and could immediately drop into our systems.
      Rate this comment: 12345
      • LLNL
        Guest (qzilla) on 06/13/2006 at 12:00 AM
        Posts:
        1
        Maybe call them on the phone?
        Rate this comment: 12345
      • LLNL
        Guest (Dave) on 06/16/2006 at 12:00 AM
        Posts:
        1
        Try the contacts here:
        http://www.llnl.gov/pao/contact/

        Including perhaps:
        Ann Willoughby, Manager, Community &
        External Relations
        willoughby1@llnl.gov
        (925) 423-4234

        Gov't labs allow for a cooperative R&D agreement that is quite useful for efforts such as yours. Good Luck!
        Rate this comment: 12345
      • Re: LLNL
        suhben on 10/14/2008 at 4:12 PM
        Posts:
        1
        It looks a suprising news for human future.
        I am very exciting to hear further development.

        Ben
        Rate this comment: 12345
  • Electrostatic Cooling
    Guest (Austin B. Carter, Jr.) on 06/12/2006 at 12:00 AM
    Posts:
    1
    Because the nanotube membrane would
    be a conductor of electricity, an
    experiment to utilize the membrane
    as an array of high voltage electrodes in electrostatic cooling of a metal plate across
    which wind is blowing
    Rate this comment: 12345
  • Gas and particle filtration
    Guest (Mark) on 06/13/2006 at 12:00 AM
    Posts:
    1
    As important as cheap desalination is in a world with dwindling potable water supplies, I'm more excited at the prospect of cheap and efficient gas and partical filtration.  Might this technology make coal-fired power generators enviromentally sound?
    Rate this comment: 12345
    • RE: Gas and particle filtration
      Guest (Justin) on 06/13/2006 at 12:00 AM
      Posts:
      1
      Just because you are able to trap the gasses escaping from a coal fired plant doesn’t mean you can dispose of them cheaply. CO2 gas still has to be put somewhere, currently we just put it back in the ground but this is just a stop gap measure and it is far from a permanent solution.
      Rate this comment: 12345
      • [no subject]
        Guest (Umm) on 06/13/2006 at 12:00 AM
        Posts:
        1
        How is putting it back in the ground a stop-gap solution? Nearly all the co2 in the world is in the ground, except for that which we've dug up and burned
        Rate this comment: 12345
        • [no subject]
          Guest (Peter) on 06/13/2006 at 12:00 AM
          Posts:
          1
          It's very hard to guarnatee that CO2 pumped into the ground will not leak, and thus places in which this is done much be closely monitored. We don't quite yet have the technology to safely replace CO2 in the ground "for sure".
          Rate this comment: 12345
      • co2
        Guest (wstephens) on 06/14/2006 at 12:00 AM
        Posts:
        1
        Nobel laureate George Olah has a whole book about what could be done with exess co2 -- turn it into methanol.
        Rate this comment: 12345
        • What do you do with the methane generated from CO2?
          Guest (Floyd) on 06/14/2006 at 12:00 AM
          Posts:
          1
          Rate this comment: 12345
          • Burn it?
            Guest (ABS) on 06/16/2006 at 12:00 AM
            Posts:
            1
            Seems that the methane would be useful as fuel source -- NG -- and thus reduce burning of coal. Not 'great', per se, but reducing burning of even worse GHG pollutant.
            Rate this comment: 12345
          • Methane
            Guest (Jordan Smith) on 06/17/2006 at 12:00 AM
            Posts:
            1
            Dude,
            Methane is NATURAL GAS
            (OK Methane is the major component of natural gas)
            Anyhow send the methane to the nearest natural pipeline or load.
            Rate this comment: 12345
            • CO2<->Methane
              Guest (Will) on 06/18/2006 at 12:00 AM
              Posts:
              1
              You guys do realize... that you have to put at minimum the amount of energy into the CO2->Methane process as you would get from burning the Methane...
              It's a non-solution.
              Rate this comment: 12345
              • Re: CO2<->Methane
                shomas on 08/17/2006 at 7:42 PM
                Posts:
                38
                Avg Rating:
                4/5
                It is only a non solution because of the cost of energy. If an energy efficient means of converting energy, carbon dioxide, and water into methane gas is found then you can store energy for later use. Instead of taking it from underground and putting more carbon dioxide into the environment.
                Rate this comment: 12345
          • Methane from C02
            Guest (Rob) on 07/25/2006 at 12:00 AM
            Posts:
            1
            explain how this is possible
            Rate this comment: 12345
    • Gas and particle filtration
      Guest (Steve) on 07/28/2006 at 12:00 AM
      Posts:
      1
      why on earth would anyone continue to use carbon based fuels if this technology can produce cleaner burning fuels such as hydrogen for much less?
      Rate this comment: 12345
  • Why doesn't the filtered salt plug the holes?
    Guest (Vick) on 06/13/2006 at 12:00 AM
    Posts:
    1
    It would have been good if the article would have explained where the filtered substance goes.  Is the filter quickly ruined by the salts, or can it be easily cleaned?
    Rate this comment: 12345
    • reject
      Guest (water) on 06/13/2006 at 12:00 AM
      Posts:
      1
      They continue down the stream into the reject flow.
      Rate this comment: 12345
    • Scale
      Guest (Bruce) on 06/13/2006 at 12:00 AM
      Posts:
      1
      At this scale, it would be a case of the salt ions simply bouncing off the "membrane" and staying in solution on the one side.
      Rate this comment: 12345
    • think differently
      Guest (Kered) on 06/16/2006 at 12:00 AM
      Posts:
      1
      This isn't a filter at the bottom of a cone, it would be lining a tube-like structure with salinated water running through it, like a common garden seep hose.
      Rate this comment: 12345
  • Cheap Water Solution
    Guest (Mike) on 06/13/2006 at 12:00 AM
    Posts:
    1
    Can an array of these be fitted to larger pipes and then lowered into the depths of the ocean as to allow the physical forces of water pressure separate the desalinated water from the surrounding water, then through the same pressures drive the cleaned water to the surface where it can be capruted and stored? Sort of like a passive separation process since salt water and distilled water will have differing densities.
    Rate this comment: 12345
    • [no subject]
      Guest on 06/13/2006 at 12:00 AM
      Posts:
      1
      if so, just put a turbine on it for your source of free perpetual energy
      Rate this comment: 12345
    • [no subject]
      Guest (Mike Bibby) on 06/13/2006 at 12:00 AM
      Posts:
      1
      As the "distilled" water passes though the salt water towards the surface it will mix with the salt water and become salinized.
      Rate this comment: 12345
    • Or not..
      Guest (Dookie) on 06/13/2006 at 12:00 AM
      Posts:
      1
      Wouldn't work like that, osmotic pressure would pull the water back through the filter.
      Rate this comment: 12345
      • Osmotic Pressure
        Guest (Mike) on 06/14/2006 at 12:00 AM
        Posts:
        1
        http://hyperphysics.phy-astr.gsu.edu/hbase/kinetic/diffus.html#c4

        I'm not an engineer per se, so your response has me stumped a little. If the Salt water is more dense, and the nano filter in place prevents salt from getting in, then the pure water - being less dense would simply fill up the tube - correct? Or is it just the opposite, where the pure water is smaller than the nano filter, and bleed back into the salt water if there is insufficient pressure to keep it moving in the right direction. If the latter - then a pump would be required to keep pure water flowing into the tube to be captured.
        Rate this comment: 12345
        • [no subject]
          Guest on 06/18/2006 at 12:00 AM
          Posts:
          1
          The higher concentration of salt in the ocean would exert a pull on the fresh water.  If you were to put a long pipe down into the ocean with one of these membranes over the ende, the freshwater column inside the pipe would not reach the surface--a pump would be necessary to pull it up to the surface.
          Rate this comment: 12345
          • [no subject]
            Guest on 06/19/2006 at 12:00 AM
            Posts:
            1
            See this:
            http://www.lhup.edu/~dsimanek/museum/osmosis.htm
            Rate this comment: 12345
  • Pollution
    Guest (Guillaume) on 06/13/2006 at 12:00 AM
    Posts:
    1
    What About stop polluating ?
    Rate this comment: 12345
    • Brine Pollution
      Guest (Nobody) on 06/13/2006 at 12:00 AM
      Posts:
      1
      What nobody ever figures out here is: What are you going to do with the brine?  Sea water is 3% salt.  Suppose we can concentrate that to 30% -- if you dump that in the ocean, you'll kill everything around.  You'll need a huge area of land to create "salt flats" where the water can evaporate without harm.
      Rate this comment: 12345
      • [no subject]
        Guest on 06/13/2006 at 12:00 AM
        Posts:
        1
        you can combine the desalinization plant with a waste water processing plant and then combine the brine with treated sewage. This treated sewage is already being poured back into the ocean
        Rate this comment: 12345
      • re: Brine pollution
        Guest (Gary Walker) on 06/13/2006 at 12:00 AM
        Posts:
        1
        All you are doing is removing a little pure water from the salty ocean. When you use the water, it returns to the ocean eventually, rediluting the infinitesimally saltier ocean.
        Rate this comment: 12345
      • Brine Pollution?
        Guest (Mike) on 06/14/2006 at 12:00 AM
        Posts:
        1
        How much water is going to be sucked out of the ocean to get 30% concentration - more importantly - where the heck will you store the clean water? Even pumping it underground, there would be enough ocean left to dilute the salt content. Back in the ice ages - when we had a lot of fresh water stored in the icepack the oceans were still capable of handling the load.
        Rate this comment: 12345
  • "It's something that is quite counter-intuitive,"
    Guest (Joel) on 06/13/2006 at 12:00 AM
    Posts:
    1
    I would imagine that capillary action allows the rigid nanotubes to pass the water more fluidly whereas traditional membranes require some pressure to coax the molecule through.
    Rate this comment: 12345
    • [no subject]
      Guest (Scott) on 06/13/2006 at 12:00 AM
      Posts:
      1
      I was thinking it might be due to water tension on a small scale.  Possibly at this scale the molecules cannot align inside the tubes so they actually flow more freely and individually.

      Of course.. I haven't taken any physics related courses in over a decade so I'm not going to pretend I actually know anything.  :)  Your theory sounds reasonable as well.
      Rate this comment: 12345
    • Cheap Water
      Guest (Debra) on 08/04/2006 at 12:00 AM
      Posts:
      1
      I want to meet the people that innovated this new nano technology!
      832-233-9122
      Rate this comment: 12345
  • Gasses
    Guest (Scott) on 06/13/2006 at 12:00 AM
    Posts:
    1
    If it can trap green houses gasses too, I'd love to have underwear made of this material so I can fart all day and not bother my coworkers.
    Rate this comment: 12345
    • never enough...
      Guest (flatulatronics) on 06/13/2006 at 12:00 AM
      Posts:
      1
      why wait for his to coem to market, you can already buy charcoal-impregnated underwear that absorbs noxious fumes from down under (and were not talking australia!)
      Rate this comment: 12345
    • Gasses
      Guest (Randy) on 06/13/2006 at 12:00 AM
      Posts:
      1
      As one of his coworkers, I would like him to have this "special" underwear too!
      Rate this comment: 12345
    • nanoscale devices...
      Guest (Rune) on 06/14/2006 at 12:00 AM
      Posts:
      1
      I'm just waiting for someone to come up with a nano-scale device to separate water into hydrogen and oxygen... :)
      Rate this comment: 12345
    • Greater good
      Guest (George) on 06/19/2006 at 12:00 AM
      Posts:
      1
      At last a way to stop him from blasting holes in the ionisphere
      Rate this comment: 12345
  • Oxygen enrichment for diesel engines
    Guest (Graham) on 06/13/2006 at 12:00 AM
    Posts:
    1
    If filters this fine could be used to  reduce the percentage of nitrogen drawn into a diesel engine then it would reduce emissions of oxides of nitrogen, reduce smoke and/or increase power output.
    Rate this comment: 12345
  • Nano-pollution?
    Guest (Ben) on 06/14/2006 at 12:00 AM
    Posts:
    1
    I know a number of nano particles can cause serious health problems (respiration and gas exchange) if ingested.  What sort of guarantees are there that we wouldn't be ingesting huge quantities of the nanotubes?
    Rate this comment: 12345
    • No, no pollution
      Guest (Geek Prophet) on 06/14/2006 at 12:00 AM
      Posts:
      1
      The article says that the nanotubes are first grown, then embedded in  silicon nitride. As a result, it is very unlikely that there will be a significant number floating in the resulting water.
      Rate this comment: 12345
    • Nano brain
      Guest (max) on 06/16/2006 at 12:00 AM
      Posts:
      1