A team of researchers from The
Australian National University have discovered a way to remove salt from
seawater using nanotubes made from boron and nitrogen atoms that will make the
process up to five times faster.
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With 25 percent of the world’s population currently affected by water
shortages, researchers Dr Tamsyn Hilder, Dr Dan Gordon and group leader Professor
Shin-Ho Chung from the Computational Biophysics Group at the Research School
of Biology at ANU have come up with a way to eliminate all salt from seawater
whilst maintaining high water flow rates. Their results have been published
in the journal Small.
With population growth and climate change limiting the world’s fresh
water stores, desalination and demineralisation are fast becoming feasible solutions.
However, there is an urgent need to make the process of desalination more effective
and less costly than current methods. Nanotechnology-based water purification
devices, such as those proposed by Hilder, Gordon and Chung, have the potential
to transform the field of desalination.
“Boron nitride nanotubes can be thought of as a hollow cylindrical tube
made up of boron and nitrogen atoms,” said Dr Hilder. “These nanotubes
are incredibly small, with diameters less than one-billionth of a meter, or
10,000 times smaller than the thickness of a single strand of human hair.
“Current desalination methods force seawater through a filter using energies
four times larger than necessary. Throughout the desalination process salt must
be removed from one side of the filter to avoid the need to apply even larger
energies.
“Using boron nitride nanotubes, and the same operating pressure as current
desalination methods, we can achieve 100 percent salt rejection for concentrations
twice that of seawater with water flowing four times faster, which means a much
faster and more efficient desalination process.”
Hilder, Gordon and Chung use computational tools to simulate the water and
salt moving through the nanotube. They found that the boron nitride nanotubes
not only eliminate salt but also allow water to flow through extraordinarily
fast, comparable to biological water channels naturally found in the body.
“Our research also suggests the possibility of engineering simple nanotubes
that mimic some of the functions of complex biological nanotubes or nanochannels,”
said Professor Chung, and work is continuing to investigate these possibilities
further. These devices, once successfully manufactured, may be used for antibiotics,
ultra-sensitive detectors or anti-cancer drugs.
A copy of the paper is available at: http://dx.doi.org/10.1002/smll.200900349
Posted August 24th, 2009
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