Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > Nanotube membranes open possibilities for cheaper desalinization

Abstract:
More permeable nanotube membranes could reduce the energy costs of desalination by up to 75 percent compared to conventional membranes used in reverse osmosis

Nanotube membranes open possibilities for cheaper desalinization

Posted on May 18, 2006

A nanotube membrane on a silicon chip the size of a quarter may offer a cheaper way to remove salt from water.

Researchers at the Lawrence Livermore National Laboratory have created a membrane made of carbon nanotubes and silicon that may offer, among many possible applications, a less expensive desalinization.

The nanotubes, special molecules made of carbon atoms in a unique arrangement, are hollow and more than 50,000 times thinner than a human hair. Billions of these tubes act as the pores in the membrane. The super smooth inside of the nanotubes allow liquids and gases to rapidly flow through, while the tiny pore size can block larger molecules. This previously unobserved phenomenon opens a vast array of possible applications.

The team was able to measure flows of liquids and gases by making a membrane on a silicon chip with carbon nanotube pores making up the holes of the membrane. The membrane is created by filling the gaps between aligned carbon nanotubes with a ceramic matrix material. The pores are so small that only six water molecules could fit across their diameter.

“The gas and water flows that we measured are 100 to 10,000 times faster than what classical models predict,” said Olgica Bakajin, the Livermore scientist who led the research. “This is like having a garden hose that can deliver as much water in the same amount of time as fire hose that is 10 times larger.”

The research resulted from collaboration between Olgica Bakajin and Aleksandr Noy, who were both recruited to Lawrence Livermore Lab as “Lawrence Fellows” – the Laboratory’s initiative to bring in young talented scientists. The principal contributors to the work are postdoctoral researcher Jason Holt and Hyung Gyu Park, a UC Berkeley mechanical engineering graduate student and student employee at Livermore.

Other LLNL co-authors included Yinmin Wang, staff scientist, Michael Stadermann, postdoctoral researcher, and Alexander Artyukhin, graduate student employee. The team collaborated with UC Berkeley’s professor of mechanical engineering Costas Grigoropoulos. David Eaglesham, now at Applied Materials, also contributed in the early stages of this work.

Membranes that have carbon nanotubes as pores could be used in desalinization and demineralization. Salt removal from water, commonly performed through reverse-osmosis, uses less permeable membranes, requires large amounts of pressure and is quite expensive. However, these more permeable nanotube membranes could reduce the energy costs of desalination by up to 75 percent compared to conventional membranes used in reverse osmosis.

Carbon nanotubes are a unique platform for studying molecular transport and nanofluidics. Their nanometer-size, atomically smooth surfaces and similarity to cellular water transport channels make them exceptionally suited for this purpose.

“Since water does not wet the outside surface of carbon nanotubes, we were skeptical that water would enter into them, let alone flow really fast,” Bakajin said. “But the molecular dynamics simulations in the literature predicted fast flow, so we wanted to test the predictions.”

“The first time we set up an experiment with water, we left it overnight thinking that the water level above the membrane would not budge,” Park said. “Instead, we came back in the morning and there was a little puddle on the floor under the membrane.”

Holt added: “The first thing that came to mind was that the membrane broke, but fortunately it didn't. The membrane allowed water through and blocked gold nanoparticles that were just a bit larger than the nanotube pores.”

Simulations of gas and water transport through carbon nanotubes predict that each should flow rapidly. Gas molecules should bounce off its atomically smooth surface like billiard balls. Water molecules should slide through either because of the “slipperiness” of the carbon nanotube surface or due to molecular ordering induced by spatial confinement. The experiments performed by the LLNL team demonstrated these predicted rapid flows of gas and water through carbon nanotubes, but further research is needed to determine the exact transport mechanisms.

Another potential application for the membranes is in gas separation. The high gas permeability and its affinity to hydrocarbons may allow for lower-energy, industrial-gas separations. “Though our membranes have an order of magnitude smaller pore size, the enhanced flow rate per pore and the high pore density makes them superior in both air and water permeability compared to conventional polycarbonate membranes,” Bakajin said.

The research appears on the cover of the May 19 edition of the journal, Science.

####

About Lawrence Livermore National Laboratory:
Founded in 1952, Lawrence Livermore National Laboratory is a national security laboratory, with a mission to ensure national security and apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy's National Nuclear Security Administration.

For more information, please click here.

Contact:
Anne M. Stark
(925) 422-9799
stark8@llnl.gov

Copyright © Lawrence Livermore National Laboratory

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Possible Futures

Dirty to drinkable: Engineers develop novel hybrid nanomaterials to transform water July 28th, 2016

Penn team uses nanoparticles to break up plaque and prevent cavities July 28th, 2016

Beating the heat a challenge at the nanoscale: Rice University scientists detect thermal boundary that hinders ultracold experiments July 28th, 2016

Enhancing molecular imaging with light: New technology platform increases spectroscopic resolution by 4 fold July 27th, 2016

Nanotubes/Buckyballs/Fullerenes

Easier, faster, cheaper: A full-filling approach to making nanotubes of consistent quality: Approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes July 19th, 2016

Sensing trouble: A new way to detect hidden damage in bridges, roads: University of Delaware engineers devise new method for monitoring structural health July 8th, 2016

Wireless, wearable toxic-gas detector: Inexpensive sensors could be worn by soldiers to detect hazardous chemical agents July 4th, 2016

Nanotubes' 'stuffing' as is: A scientist from the Lomonosov Moscow State University studied the types of carbon nanotubes' 'stuffing' June 2nd, 2016

Announcements

Dirty to drinkable: Engineers develop novel hybrid nanomaterials to transform water July 28th, 2016

Thomas Swan and NGI announce unique partnership July 28th, 2016

Penn team uses nanoparticles to break up plaque and prevent cavities July 28th, 2016

Beating the heat a challenge at the nanoscale: Rice University scientists detect thermal boundary that hinders ultracold experiments July 28th, 2016

Water

Dirty to drinkable: Engineers develop novel hybrid nanomaterials to transform water July 28th, 2016

New nontoxic process promises larger ultrathin sheets of 2-D nanomaterials July 27th, 2016

Electricity generated with water, salt and a 3-atoms-thick membrane: EPFL researchers have developed a system that generates electricity from osmosis with unparalleled efficiency. Their work, featured in Nature, uses seawater, fresh water, and a new type of membrane just 3 atoms July 15th, 2016

Bouncing droplets remove contaminants like pogo jumpers: Researchers at Duke University and the University of British Columbia are exploring whether surfaces can shed dirt without being subjected to fragile coatings July 7th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic