Nanotubes made from boron and nitrogen atoms can remove salt from seawater five times faster, say researchers from The Australian National University.
As much as 25 percent of the world's population are currently affected by water shortages. Besides population growth and climate change limit the world's fresh water stores. Hence scientists are eyeing desalination and demineralisation more keenly than eve. However, there is an urgent need to make the process of desalination more effective and less costly than current methods.
In such a backdrop, the ANU research gains significance. 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 Australian National University 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
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.