New Desalination Method Shocks The Salts Out Of Water | November 23, 2015 Issue - Vol. 93 Issue 47 | Chemical & Engineering News
Volume 93 Issue 47 | p. 6 | News of The Week
Issue Date: November 30, 2015 | Web Date: November 23, 2015

New Desalination Method Shocks The Salts Out Of Water

Environment: Prototype device uses electrodialysis to produce freshwater
Department: Science & Technology
News Channels: Environmental SCENE, Materials SCENE
Keywords: desalination, shock electrodialysis
Electric current running through this device generates a shockwave that separates salty and fresh water.
Credit: Martin Bazant
 A prototype device with input for salty water, which flows through porous glass beads sandwiched between two electrodes.
Electric current running through this device generates a shockwave that separates salty and fresh water.
Credit: Martin Bazant

A novel method for water desalination separates salt water into briny and fresh streams with the help of an electric shock wave (Env. Sci. & Tech. Lett. 2015, DOI: 10.1021/acs.estlett.5b00303)

As more and more people live in areas affected by drought or contaminated water, desalination is becoming an important way to meet global drinking water needs. So scientists continue to develop ever simpler and less expensive desalination methods.

Current technologies, for example, frequently rely on membranes to filter out ions. These membranes eventually get clogged and must be replaced, increasing costs.

In recent years, scientists have been exploring electrochemical methods of removing salts from water. For example, one group has designed a method where pairs of capacitive electrodes are first dipped in salt water to absorb salt, and then in a brine chamber, where they discharge the salt.

Now, a team led by Martin Z. Bazant at Massachusetts Institute of Technology has demonstrated another method with a prototype device composed of porous glass beads, known as a frit, sandwiched between two electrodes. They applied a current across the electrodes as salt water flowed through the frit, causing some areas of the stream to collect more ions while others became ion depleted.

When the electrical current became strong enough, it induced a shockwave that separated these regions into two streams—one briny, one fresh—a phenomenon known as shock electrodialysis.

The device continuously removed up to 99.99% of salts, including sodium, chloride and other ions, from a saltwater stream.

“This new system seems very promising indeed,” says P. Maarten Biesheuvel, a principal scientist at Wetsus, European Centre of Excellence for Sustainable Water Technology, who helped develop the capacitive electrode desalination technology.

Biesheuvel says that compared with his method, the electroshock method “has the major advantage that we don’t need any moving parts,” he says.

The method may have other advantages, says the new study’s coauthor Sven Schlumpberger. For example, the electoral current might kill pathogenic bacteria.

The MIT team says the next step will be to design scaled-up versions of their prototype to test the method’s industrial feasibility.

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dusko cakara (November 25, 2015 1:55 PM)
You should correct the URL in the link, change http://dx.doi.rog/10.1021/acs.estlett.5b00303 for
DG Barnes (November 25, 2015 6:14 PM)
Great stuff, chemically.
Where does it seem to be headed economically -- money-wise and energy-wise?

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