Chemists Work to Desalt the Ocean for Drinking Water, One Nanoliter at a Time

June 27, 2013

AUSTIN, Texas —

water chip, Electrochemically Mediated Seawater Desalination

A prototype "water chip" developed by researchers at The University of Texas at Austin in collaboration with a startup company.

By creating a small electrical field that removes salts from seawater, chemists at The University of Texas at Austin and the University of Marburg in Germany have introduced a new method for the desalination of seawater that consumes less energy and is dramatically simpler than conventional techniques. The new method requires so little energy that it can run on a store-bought battery.

The process evades the problems confronting current desalination methods by eliminating the need for a membrane and by separating salt from water at a microscale.

The technique, called electrochemically mediated seawater desalination, was described last week in the journal Angewandte Chemie. The research team was led by Richard Crooks of The University of Texas at Austin and Ulrich Tallarek of the University of Marburg. It’s patent-pending and is in commercial development by startup company Okeanos Technologies.

“The availability of water for drinking and crop irrigation is one of the most basic requirements for maintaining and improving human health,” said Crooks, the Robert A. Welch Chair in Chemistry in the College of Natural Sciences. “Seawater desalination is one way to address this need, but most current methods for desalinating water rely on expensive and easily contaminated membranes. The membrane-free method we’ve developed still needs to be refined and scaled up, but if we can succeed at that, then one day it might be possible to provide fresh water on a massive scale using a simple, even portable, system.”

This new method holds particular promise for the water-stressed areas in which about a third of the planet’s inhabitants live. Many of these regions have access to abundant seawater but not to the energy infrastructure or money necessary to desalt water using conventional technology. As a result, millions of deaths per year in these regions are attributed to water-related causes.

“People are dying because of a lack of freshwater,” said Tony Frudakis, founder and CEO of Okeanos Technologies. “And they’ll continue to do so until there is some kind of breakthrough, and that is what we are hoping our technology will represent.”

desalination

The left panel shows the salt (which is tagged with a fluorescent tracer) flowing upward after a voltage is applied by an electrode (the dark rectangle) jutting into the channel at just the point where it branches. In the right panel no voltage is being applied.

To achieve desalination, the researchers apply a small voltage (3.0 volts) to a plastic chip filled with seawater. The chip contains a microchannel with two branches. At the junction of the channel an embedded electrode neutralizes some of the chloride ions in seawater to create an “ion depletion zone” that increases the local electric field compared with the rest of the channel. This change in the electric field is sufficient to redirect salts into one branch, allowing desalinated water to pass through the other branch.

“The neutralization reaction occurring at the electrode is key to removing the salts in seawater,” said Kyle Knust, a graduate student in Crooks’ lab and first author on the paper.

Like a troll at the foot of the bridge, the ion depletion zone prevents salt from passing through, resulting in the production of freshwater.

Thus far Crooks and his colleagues have achieved 25 percent desalination. Although drinking water requires 99 percent desalination, they are confident that goal can be achieved.

“This was a proof of principle,” said Knust. “We’ve made comparable performance improvements while developing other applications based on the formation of an ion depletion zone. That suggests that 99 percent desalination is not beyond our reach.”

The other major challenge is to scale up the process. Right now the microchannels, about the size of a human hair, produce about 40 nanoliters of desalted water per minute. To make this technique practical for individual or communal use, a device would have to produce liters of water per day. The authors are confident that this can be achieved as well.

If these engineering challenges are surmounted, they foresee a future in which the technology is deployed at different scales to meet different needs.

“You could build a disaster relief array or a municipal-scale unit,” said Frudakis. “Okeanos has even contemplated building a small system that would look like a Coke machine and would operate in a standalone fashion to produce enough water for a small village.”

The fundamental scientific breakthroughs that led to this advance were primarily supported by the Office of Basic Energy Sciences in the U.S. Department of Energy. Okeanos Technologies is funded by venture capital and grants from the U.S. Environmental Protection Agency. The intellectual property is owned by The University of Texas at Austin through the Office of Technology Commercialization (OTC). In the event of eventual profits, patent holders, including Crooks and Knust, will be paid according to the OTC’s standard licensing agreement. Okeanos Technologies is also currently supporting Knust’s stipend and tuition via a gift to UT. 

For more information, contact: Daniel Oppenheimer, Hogg Foundation, 512 745 3353; Richard Crooks, 512-475-8639, crooks@cm.utexas.edu.

To view a linked PDF file in this article, you must first download the Acrobat Reader plug-in for your browser.

26 Comments to "Chemists Work to Desalt the Ocean for Drinking Water, One Nanoliter at a Time"

1.  qamarwali said on June 27, 2013

pleas tell me that which is the best materials for making solar cells.
i am waiting for your humble reply.
thnks,
Bests,

2.  Will Fox said on June 28, 2013

You should add a tweet button, it would make this story (and others) easier to share.

3.  Todd Quinton said on June 28, 2013

Great article, looking fwd to seeing it applied to larger scales in the future!

4.  Brian Kenward said on June 28, 2013

What other ions may have been diverted with this method to date?
Have you alrready tested multi-stage series systems?
What are the effects of temperature and/or pressure on the method?
Have you experimented with any other geometry in the micro channel?

5.  Dheeraj Kalgutkar said on June 29, 2013

Kudos to the giants who formulated such pathbreaking research. Yes. No doubt in it that it will replace if successful the conventional membrane dependant techniques plus this one is cost effective too... So FULL PROOF!
@meetdheeraj

6.  Charles Gallagher said on June 29, 2013

The potential benefits are enormous; from the small scale individual units in third world countries to the very large conversion units that might be used to counter the secondary effects of global warming. We are not going to be able to reverse global warming for centuries; so it is necessary to better handle the effects.

7.  Roger said on June 29, 2013

this is great news . How are you going to feed all the people you save with this and what about the pollution they will cause ? Good luck with that .

8.  Antony Chipman said on June 29, 2013

As the Earth ages, salts accumulate in the sea. That means that it was fresher in the past.

How can an industrial process be called 'desalination,' if it results increased oceanic salinity?

Have any environmental impact parameters been addressed relating to this technology?

It certainly has the potential to desalinate, but not used in the proposed fashion.

9.  Mark Jones said on June 30, 2013

Very interesting phenomenon and some fine inventive thinking - I hope this pans out, for all concerned, given the essential need for clean water. If this can work at 99% and scale up it ought to help. Good luck!

I'd like to get the pdf file but I run Firefox on Linux and see no good reason to use an insecure proprietary plugin.

10.  Andres Espina said on June 30, 2013

To increase the overall performance of the desalination by ion depletion, the 25% desalinated water could be passed thru several stages. Also, the addition of a centrifugal force might help to the electric field to separate the heavier brine from the freshwater.

11.  tom gallagher said on July 1, 2013

for someone who has filtered brackish water in theater in Iraq for our troops with R/O I find this method highly intriguing and less cumbersome than the huge investment in material and personnel and energy that R/O requires.

12.  paul baker said on July 1, 2013

Wonderful! I would love to help it reach the world and be a part of it

13.  Darrell McEver said on July 1, 2013

This isn't going to work without a great deal of attention being paid to all the contaminants in sea water. I remind everyone that sea water is not simply salt water. It is just as suited for mining precious metals as it is for filtering fresh water. This article makes no mention of the energy requirements to perform this trick. It is mostly fluff with no real engineering data.

14.  Robert Pollock said on July 1, 2013

Gee, I have an Intex swimming pool water salinating system. It cost $130 and manages to salinate about 4000 gl of water. I eats up about 1 Amp per hour or less. There is a heavy copper electrode that in energized as the water passes through it.

Is this process just the opposite?

15.  Ben Welgoed said on July 1, 2013

Looks like a worthwhile solution to a problem, however, it would eliminate any motive for people to not alter the climate whereby seriously arid regions are created. That change destroys regional flora and fauna in large regions on the planet. So, yes it's a nice technology, but it does eliminate one of the few natural brakes on humanity's ever expanding intrusion of the natural world.

16.  Lucas said on July 1, 2013

To Roger quote "this is great news . How are you going to feed all the people you save with this and what about the pollution they will cause ? Good luck with that ."

You're absolutely right it's so obvious...the only good human is a dead human, am I right! We should all just do the world a favor and kill ourselves. Here, you go first!

Wow hope you caught the sarcasm.

17.  Frank said on July 1, 2013

Could this tech be used in a life raft as a method of changing the sea water to drinkable water in an emergency? Part of a survival kit ?

18.  ron wells said on July 1, 2013

there are numerious applications I see....

19.  Nathan said on July 1, 2013

Gee, I have an Intex swimming pool water salinating system. It cost $130 and manages to salinate about 4000 gl of water. I eats up about 1 Amp per hour or less. There is a heavy copper electrode that in energized as the water passes through it.

Is this process just the opposite?

NO. You can stir a teaspoon of salt and dissolve it in a cup of water but you cannot stir the salt out of a glass of salt water.

20.  roger said on July 8, 2013

This will cause as many problems as it will solve - who is considering the issue that will 'flow' from this??

21.  John Hunter said on July 15, 2013

Please, when can I get such a system for my yacht?
The available R.O systems use huge amounts of power and the current draw is always a fire hazard. I have plenty of 12 volt battery capacity.

Many thanks

John

22.  Elia said on July 16, 2013

Question:
could it be in the future, a replacement for SWRO or for MSF? talking about a medium plant of 20000 cm/d of SWRO permeate, could it be a valid alternative or is a better application for small scale plants?
what kind of pretreatment it would require?

23.  rejie quimiguing said on July 16, 2013

can this technology also remove organic contaminants?, dissolve noxious gas/air contaminants, bacteria. viruses, odor ? if not then reverse osomosis is still the ideal way to desalinate sea water

24.  reijo said on July 17, 2013

If technique is success, would it just help increasing human population that will consume earth resources by accelerating pace? Well, potentially astronomically big money involved, so who cares about the real detriments, only benefits are going to be advertised..

25.  Jack Simmons said on July 23, 2013

Let's see what the environmental impact of this technology would be in terms of salt concentrations.

There are 1.87 x 10**20 gallons of water in oceans.

There are 1.87 x 10**18 gallons of total fresh water in the world. This is the available water, streams, lakes, rivers, etc.

Each gallon of seawater has 0.25 lbs of salt.

If mankind were to desalinate the equivalent of all the fresh water in the world and return the salt to the ocean, the salt content would rise to 0.26 lbs of salt per gallon.

Of course the above ignores the fact all the used water would be returned to the oceans, restoring the salt content to its original concentrations. This is known as the water cycle.

I would like to suggest there would be negligible environmental impact from this technology due to the above calculations.

Once you have fresh water, it is trivial to remove other contaminants.

For those concerned about there being too many people, feel free to check out at any time. Don't be like Al Gore preaching to everyone about cutting back while enjoying the rich man's life style.

I prefer to see real human needs to be provided for; people's families and animals.

26.  Dorkyman said on July 23, 2013

I just love the pessimist's comments here. Just can't make some folks happy.

When I was an engineering student many years ago I read in a very old Scientific American an article about pollution. It stated that at the current rate of growth, the streets of Manhattan would be under 3 feet of horse manure by the year 1950. It was not meant as a joke.