Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

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

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Nanotubes/Buckyballs/Fullerenes

Programmable materials find strength in molecular repetition May 23rd, 2016

Nanotubes are beacons in cancer-imaging technique: Rice University researchers use spectral triangulation to pinpoint location of tumors May 21st, 2016

Unveiling the electron's motion in a carbon nanocoil: Development of a precise resistivity measurement system for quasi-one-dimensional nanomaterials using a focused ion beam May 16th, 2016

New research shows how silver could be the key to gold-standard flexible gadgets: Silver nanowires are an ideal material for current and future flexible touch-screen technologies May 13th, 2016

Announcements

Finding a new formula for concrete: Researchers look to bones and shells as blueprints for stronger, more durable concrete May 26th, 2016

Deep Space Industries and SFL selected to provide satellites for HawkEye 360’s Pathfinder mission: The privately-funded space-based global wireless signal monitoring system will be developed by Deep Space Industries and UTIAS Space Flight Laboratory May 26th, 2016

The next generation of carbon monoxide nanosensors May 26th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Water

Mille-feuille-filter removes viruses from water May 19th, 2016

First single-enzyme method to produce quantum dots revealed: Biological manufacturing process, pioneered by three Lehigh University engineers, produces equivalent quantum dots to those made chemically--but in a much greener, cheaper way May 9th, 2016

Understanding tiny droplets can make for better weather forecasts: Climate change models also benefit from understanding fundamental thermodynamics of water droplets May 6th, 2016

Engineers create a better way to boil water -- with industrial, electronics applications May 5th, 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