Science

Faster, more efficient desalination process using carbon nanotubes developed

Faster, more efficient desalin...
Prof. Somenath Mitra has developed a membrane incorporating carbon nanotubes, that could lead to a faster and more energy-efficient method of water desalination (Photo: NJIT)
Prof. Somenath Mitra has developed a membrane incorporating carbon nanotubes, that could lead to a faster and more energy-efficient method of water desalination (Photo: NJIT)
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Prof. Somenath Mitra has developed a membrane incorporating carbon nanotubes, that could lead to a faster and more energy-efficient method of water desalination (Photo: NJIT)
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Prof. Somenath Mitra has developed a membrane incorporating carbon nanotubes, that could lead to a faster and more energy-efficient method of water desalination (Photo: NJIT)

When it comes to desalinating salt water, two of the main options are thermal distillation and reverse osmosis. Thermal distillation involves boiling the water and collecting the resulting freshwater condensation, while reverse osmosis involves pressurizing the salt water and forcing it through a semipermeable membrane, which will allow water molecules to pass through, but not salt. Both of these methods, however, require a considerable amount of energy – not as environmentally sound as they could be, nor entirely practical for use in developing nations, where electricity isn't readily available. Now, however, a newly-developed membrane that incorporates carbon nanotubes could make desalination much quicker, easier and energy-efficient.

The patent-pending membrane, developed by New Jersey Institute of Technology chemist Somenath Mitra, utilizes another already-existing form of desalination known as membrane distillation. Sort of like a cross between thermal distillation and reverse osmosis, it involves heating the salt water then passing it through a tube made from a semipermeable membrane, which allows water vapor to pass through while not admitting salt molecules.

Because the water is only heated to 60-90C (140-194F) and isn't pressurized, membrane distillation uses less energy than either of the other two methods. Unfortunately, it can be difficult to achieve the right degree of permeability in the membrane, and even a temperature of 60C could still be difficult to attain in impoverished conditions.

In Prof. Mitra's new material, carbon nanotubes are immobilized in the membrane's pores. This reportedly results in much greater vapor permeation while keeping liquid water from clogging the pores, and it allows for higher flow rates while requiring lower temperatures – as compared to a regular membrane, it demonstrated the same level of salt reduction at a temperature that was 20C cooler, and at a flow rate that was six times higher.

"Together these benefits lead to a greener process which could make membrane distillation economically competitive with existing desalination technologies, and we hope could provide potable water where it is most needed," said Mitra.

6 comments
Facebook User
Hope this will come to market fast. Need of the hour. May some corporate / Government come out soon.
yodecat
Look at this link from 1996 http://www.technologyreview.com/Nanotech/16977/?a=f This article is hardly news.
jaison Sibley
In countries like Saudi Arabia or deserts next to seashores where surface temperature reaches 50 to 80 degrees celcius under the sun for minimum of 5 hours daily , will be an ideal place to desalinate getting heat from solar energy and will only need power for a pump (solar panels...)
Slowburn
Improving the efficiency of desalinating water is good, but a steam cycle electrical power plant can operate as a thermal distillation plant with only a slight loss of efficiency. Also the concentrated brine left behind can be a valuable resource; just look at what the Israelis get out of the dead sea.
Dan Vasii
What about the possibility that nanoparticles to get into the water and from there in organisms? What effects might produce? Nanoparticles can probably penetrate much easily the membrane of a cell, entering it and changing its way of functioning.
kawar.mahendra
Indeed good preposition for coastal and desert area where water is saline and paucity. how it will commercialize is to be seen . eagerly waiting for the supply of membranes