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New membrane will help to ensure many parts of the world have easy access to drinking water.

One of the biggest, but least appreciated problems facing many regions of the world is lack of clean drinking water, a common problem in impoverished nations.  Ironically, many of these nations rest beside large bodies of salt water. Ttypically, processing salt water into fresh water is expensive and requires large dedicated plants.

DailyTech previously chronicled how wind-power driven desalinization plants which used membranes were being developed.  Now another major breakthrough in the field has been devised, this time concerning the membranes.

Researchers from several international universities have developed a chlorine-tolerant membrane which turns salt water into clean drinking water.  Typically, salt water is treated with chlorine to remove bacteria and microorganisms that would grow and form a biofilm on the membrane, blocking it.  However, chlorine destroys past membranes which were build using amide-polymers (nitrogen based).  This meant that that the water had to be dechlorinated before being sent to the membrane, a relatively expensive and complex process.

The new membrane is formed from sulfonated copolymers.  It took researchers Professor Benny Freeman with the The University of Texas at Austin, James E. McGrath of Virginia Tech University, and Ho Bum Park of the University of Ulsan in South Korea three years to develop the membrane for which they have filed a patent.  The new membrane is resistant to chlorine allowing the elimination of dechlorination.

Says Professor Freeman, "If we make the desalination process more efficient with better membranes, it will be less expensive to desalinate a gallon of water, which will expand the availability of clean water around the world.  It promises to eliminate de-chlorination steps that are required currently to protect membranes from attack by chlorine in water.  We believe that even a small increase in efficiency should result in large cost savings."

Researchers also believe the design will help reduce carbon dioxide emissions in developing nations by decreasing the electrical needs of the generation process. 

Professor Freeman explains:

Energy and water are inherently connected.  You need water to generate power (cooling water for electric power generation stations) and generation of pure water requires energy to separate the salt from the water. That energy is often generated from the burning of fossil fuels, which leads inevitably to the generation of carbon dioxide. Therefore, if one can make desalination more energy-efficient by developing better membranes, such as those that we are working on, one could reduce the carbon footprint required to produce pure water.

It was a combination of luck and hard work that brought the researchers upon the novel suflonated class of membranes.  This class of materials enjoys a high tolerance to aqueous chlorine, making it surprisingly a far better fit than membrane materials currently in use.

Professor Freeman, who holds the Kenneth A. Kobe Professorship in Chemical Engineering and the Paul D. & Betty Robertson Meek & American Petrofina Foundation Centennial Professorship in Chemical Engineering, states, "Basically, Dr. McGrath radically changed the chemical composition of the membranes, relative to what is used commercially, and the new membranes do not have chemical linkages in them that are sensitive to attack by chlorine."

The research was funded by the Office of Naval Research and the National Science Foundation-Partnerships for Innovation Program. 

The findings will be reported in a paper in this month's edition of the German Chemical Society's journal, Angewandte Chemie, with Mehmet Sankir and Zhong-Bio Zhang, both of Virginia Tech, as additional coauthors.



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RE: Swank.
By masher2 (blog) on 7/24/2008 9:03:25 AM , Rating: 2
> "Note that most of all that '500mm' average you quote comes from the northern coastal fringes. "

The average rainfall in the Sydney basin is 1200 mm -- over twice the average for the entire continent. The average rainfall in Perth is 870 mm -- 50% more the the continental mean. Adelaide's rainfall: 629 mm. Melbourne's rainfall: 800mm.

Yes, more rain falls in the tropical North. But when over 1700 times as much rain falls as you actually need, even the rainfall in the south is sufficient -- were it all to be properly used.

Take a look at any Australian river flowing into the sea. That's fresh water-- all wasted. The Fitzroy river alone has been measured at flow rates up to 640 billion gallons per *day*. The Murray river -- easily available in the south -- discharges some 17 billion gallons a day. Again, all wasted.

As for the "protected rainforest, wetlands, etc" -- that's simply more proof this is a problem of desire and initiative, rather than substance. The north is too wet, and the south too dry. The solution to that problem should be obvious to anyone....transfer some water.


RE: Swank.
By andrinoaa on 7/24/2008 6:33:11 PM , Rating: 2
You obviously don't live here, mash. Its not what we have on the ground. Melbourne hasn't had decent rain for nearly two decades. We have lots of dams but they are running on empty. What is the point of having more?
Lies , damn lies and stastistics.
And besides, what arrogance you have. All water that flows to the sea is wasted!?!?!? Thats the kind of thinking that has destroyed half the environment in the fisrt place totally IGNORANT thinking. Its time you stopped defecating in your cereal bowl, mate.


RE: Swank.
By andrinoaa on 7/24/2008 6:44:32 PM , Rating: 2
The Murray river stopped flowing to the sea years ago. The mouth is now threatening to turn acidic PERMANENTLY. This will cause untold ecologoical damage to the area. Agriculture may need to be abandoned and south australia's water supplies are threatened too. Your rainfall figures look great but are not reflective of what we see.
Let me repeat. Damming the far north and piping water south is too expensive because of the distance so we need to find local initiatives. Now, next time you chosse to look up information in google, make sure its relevant. Not VAPOURWARE


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