Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > A system that’s worth its salt

A single unit of the new desalination device, fabricated on a layer of silicone. In the Y-shaped channel (in red), seawater enters from the right, and fresh water leaves through the lower channel at left, while concentrated brine leaves through the upper channel.  Photo: Patrick Gillooly
A single unit of the new desalination device, fabricated on a layer of silicone. In the Y-shaped channel (in red), seawater enters from the right, and fresh water leaves through the lower channel at left, while concentrated brine leaves through the upper channel. Photo: Patrick Gillooly

Abstract:
New approach to water desalination could lead to small, portable units that could be sent to disaster sites or remote locations.

By David L. Chandler, MIT News Office

A system that’s worth its salt

Cambridge, MA | Posted on March 23rd, 2010

Potable water is often in high demand and short supply following a natural disaster like the Haiti earthquake or Hurricane Katrina. In both of those instances, the disaster zones were near the sea, but converting salty seawater to potable fresh water usually requires a large amount of dependable electrical power and large-scale desalination plants — neither of which were available in the disaster areas.

A new approach to desalination being developed by researchers at MIT and in Korea could lead to small, portable units that could be powered by solar cells or batteries and could deliver enough fresh water to supply the needs of a family or small village. As an added bonus, the system would also remove many contaminants, viruses and bacteria at the same time.

The new approach, called ion concentration polarization, is described in a paper by Postdoctoral Associate Sung Jae Kim and Associate Professor Jongyoon Han, both in MIT's Department of Electrical Engineering and Computer Science, and colleagues in Korea. The paper was published on March 21 in the journal Nature Nanotechnology.

One of the leading desalination methods, called reverse osmosis, uses membranes that filter out the salt, but these require strong pumps to maintain the high pressure needed to push the water through the membrane, and are subject to fouling and blockage of the pores in the membrane by salt and contaminants. The new system separates salts and microbes from the water by electrostatically repelling them away from the ion-selective membrane in the system — so the flowing water never needs to pass through a membrane. That should eliminate the need for high pressure and the problems of fouling, the researchers say.

The system works at a microscopic scale, using fabrication methods developed for microfluidics devices — similar to the manufacture of microchips, but using materials such as silicone (synthetic rubber). Each individual device would only process minute amounts of water, but a large number of them — the researchers envision an array with 1,600 units fabricated on an 8-inch-diameter wafer — could produce about 15 liters of water per hour, enough to provide drinking water for several people. The whole unit could be self-contained and driven by gravity — salt water would be poured in at the top, and fresh water and concentrated brine collected from two outlets at the bottom.

That small size could actually be an advantage for some applications, Kim explains. For example, in an emergency situation like Haiti's earthquake aftermath, the delivery infrastructure to get fresh water to the people who need it was largely lacking, so small, portable units that individuals could carry would have been especially useful.

So far, the researchers have successfully tested a single unit, using seawater they collected from a Massachusetts beach. The water was then deliberately contaminated with small plastic particles, protein and human blood. The unit removed more than 99 percent of the salt and other contaminants. "We clearly demonstrated that we can do it at the unit chip level," says Kim. The work was primarily funded by a grant from the National Science Foundation, as well as a SMART Innovation Centre grant.

While the amount of electricity required by this method is actually slightly more than for present large-scale methods such as reverse osmosis, there is no other method that can produce small-scale desalination with anywhere near this level of efficiency, the researchers say. If properly engineered, the proposed system would only use about as much power as a conventional lightbulb.

Mark A. Shannon of the Center of Advanced Materials for the Purification of Water with Systems at the University of Illinois at Urbana-Champaign, who was not involved in this work, agrees with that assessment. In a News & Views piece that accompanies the Nature Nanotechnology paper, he writes that the new system achieves "perhaps the lowest energy ever for desalinating microliters of water," and when many of these micro-units are combined in parallel, as Kim and his co-authors propose, "it could be used to supply liters of water per hour using only a battery and gravity flow of water." That meets a significant need, he says, since at present there are few efficient methods for small-scale desalination, both for emergencies and for use in remote areas in poor countries.

Alex Iles, a research scientist at the University of Hull in Britain, says that while further testing must be done to establish long-term stability and fabrication techniques, "This is an elegant new concept for water desalination." He says it is likely to produce a low-cost, low-maintenance system that could be "ideal for applications such as disaster relief." When it was initially presented at a conference he attended last year, Iles says, "I thought it was probably the most significant new work at the entire conference, even though it was only a poster."

The basic principle that makes the system possible, called ion concentration polarization, is a ubiquitous phenomenon that occurs near ion-selective materials (such as Nafion, often used in fuel cells) or electrodes, and this team and other researchers have been applying the phenomenon for other applications such as biomolecule preconcentration. This application to water purification has not been attempted before, however.

Since the separation occurs electrostatically, it doesn't work for removing contaminants that have no electric charge. To take care of these remaining particles — mostly industrial pollutants — the researchers suggest the unit could be combined with a conventional charcoal filter system, thus achieving pure, safe drinking water through a single simple device.

Having proved the principle in a single-unit device, Kim and Han plan to produce a 100-unit device to demonstrate the scaling-up of the process, followed by a 10,000-unit system. They expect it will take about two years before the system will be ready to develop as a product.

"After that," says Kim, "we'll know if it's possible" for this to work as a robust, portable system, "and what problems might need to be worked on."

####

For more information, please click here

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

News and information

Silicene Labs Announces the Launch of Patent-Pending, 2D Materials Composite Index™ : The Initial 2D Materials Composite Index™ for Q2 2014 Is: 857.3; Founders Include World-Renowned Physicist and Seasoned Business and IP Professionals July 24th, 2014

Iranian Scientists Produce Transparent Nanocomposite Coatings with Longer Lifetime July 24th, 2014

Deadline Announced for Registration in 7th Int'l Nanotechnology Festival in Iran July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Microfluidics/Nanofluidics

Toward a new way to keep electronics from overheating July 2nd, 2014

New particle-sorting method breaks speed records: Discovery could lead to new ways of detecting cancer cells or purifying contaminated water July 1st, 2014

Micro-manufacturing breakthrough is wired for sound June 24th, 2014

Fully automated DNA lab-on-a-chip microfluidic system wins Dolomite’s Productizing Science® competition 2013 June 10th, 2014

Possible Futures

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Virus structure inspires novel understanding of onion-like carbon nanoparticles April 10th, 2014

Local girl does good March 22nd, 2014

Surface Characteristics Influence Cellular Growth on Semiconductor Material March 12th, 2014

Academic/Education

Haydale Announces Collaboration Agreement with Swansea University’s Welsh Centre for Printing and Coatings (WCPC) July 12th, 2014

STFC takes delivery of the 100th Hitachi Tabletop SEM in the UK July 3rd, 2014

Innovation Management and the Emergence of the Nanobiotechnology Industry July 1st, 2014

Albany NanoCollege Faculty Member Selected as Editor-in-Chief of the Prestigious Journal of Electronic Materials July 1st, 2014

Announcements

Silicene Labs Announces the Launch of Patent-Pending, 2D Materials Composite Index™ : The Initial 2D Materials Composite Index™ for Q2 2014 Is: 857.3; Founders Include World-Renowned Physicist and Seasoned Business and IP Professionals July 24th, 2014

Iranian Scientists Produce Transparent Nanocomposite Coatings with Longer Lifetime July 24th, 2014

Deadline Announced for Registration in 7th Int'l Nanotechnology Festival in Iran July 23rd, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Water

Researchers Use Various Zinc Oxide Nanostructures to Boost Efficiency of Water Purification Process July 13th, 2014

Harris & Harris Group Continues Its Blog Series to Highlight Most Impactful Portfolio Companies With Produced Water Absorbents, Inc. July 9th, 2014

LED Lamps Implemented in Removal of Pollutants from Water by Using Nanocatalysts July 1st, 2014

New particle-sorting method breaks speed records: Discovery could lead to new ways of detecting cancer cells or purifying contaminated water July 1st, 2014

Grants/Awards/Scholarships/Gifts/Contests/Honors/Records

Hysitron is Awarded TWO R&D 100 Awards for Highly Innovative Technology Developments in the Areas of Extreme Environments and Biological Mechanical Property Testing July 23rd, 2014

Researchers create vaccine for dust-mite allergies Main Page Content: Vaccine reduced lung inflammation to allergens in lab and animal tests July 22nd, 2014

EPFL Research on the use of AFM based nanoscale IR spectroscopy for the study of single amyloid molecules wins poster competition at Swiss Physics Society meeting July 22nd, 2014

Carbyne morphs when stretched: Rice University calculations show carbon-atom chain would go metal to semiconductor July 21st, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE