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Super-foam makes contaminated water fit to drink

posted 21 Jul 2011, 07:33 by Mpelembe   [ updated 21 Jul 2011, 07:36 ]

Researchers at North Carolina State University have created and eco-friendly super absorbent foam they say could revolutionise efforts to purify drinking water in developing countries and disaster-stricken areas. The foam has the ability to remove a wide range of contaminants from water - from salt and heavy metals to radioactive materials.

REUTERS, TEPCO -  It started as an experiment to create an absorbent material for the next generation of diapers, but it turned out to be so much more.

Using by-products from the lumber industry and pulverised crustacean shells, Joel Pawlak and his team at North Carolina State University came up with a foam substance with absorbent properties beyond anything they'd expected.


"So we started looking at how this product works, how this product works in taking up saline or salt water. And through that process we found out that not only does it take up a whole lot of salt water, it also takes a lot of the salt out of the water. So it is actually sort of a salt sucker."

And the implications are significant. In countries where fresh drinking water is in short supply, Pawlak says his foam could one day be used to extract salt from sea water before final purification in a desalination plant, thereby increasing the plants' efficiency.

Having demonstrated its salt extraction abilities, Pawlak was curious about what else the foam could do.


"So we took this material and now that we knew it can take up water. If it could remove salt from water we were curious to see if it could remove heavy metals from water. And what we were able to find out is that indeed it does remove heavy metals quite well from water."

In this experiment, researchers are dissolving large amounts of arsenic in water to simulate the contaminated water sometimes found in fresh water wells in India and Bangladesh.

They measure the amount of arsenic in the water and then add a tea bag containing the foam. Five minutes later, the amount of arsenic in the water has decreased by more than 70 percent.


"We are using a material that has positive and negative charges that are right now attached together. When we put that into water those positive and negative charges come apart and allow for salt, the positive and the negative ions of that salt attack to those charges inside the foam. We actually think that there is a possibility that when we put this in there and that ones up it will actually bind viruses, will bind bacteria into this material as well."

Pawlak says that since his foam comprises by-products of existing industries, it can be easily mass produced to provide people contaminant-free water, and that includes water poisoned by radioactivity. After the recent nuclear crisis in Japan, Pawlak and his team tested the foam's ability to remove radioactive material from water and, once again, it performed well.

The next generation of diapers, says Pawlak, won't know what hit them.

Ben Gruber, Reuters.