I’ve been seeking all sorts of ways to make sure folks around the world don’t run out of water. It’s not just the 7 Western States that are in trouble, it’s Africa, it’s Asia- it’s basically everywhere.
We’ve discussed a wind turbine that effectively plucks water (from humidity) in the air. Producing 1000L of water a day, but with a capital cost of around $ 750K, a bit much for developing regions.
But, humidity in air is really a viable source for water. We know there’s some 13000 cubic kilometers of water vapor in our atmosphere. How can we recover some of that water for those places desperately short of water?
What about using a hydrogel? This film might let us recover enough water for drinking as long as the humidity levels are 15% or more. (Just so you know, that’s the humidity of Las Vegas in the hot summer months.)
As long as the hydrogel has a reasonable acquisition cost, of course. Which is what DARPA (Defense Advanced Research Projects Agency) (funding Dr. Youhong Guo, a ChemE post doc at MIT, continuing her PhD work from UT Austin) has been trying to perfect, so that soldiers in desert area will have enough water.
Dr. Guo (along with her professor, Dr. G Yu, with W Guan, C Lei, H Lu, and W Shi, all from the Material Science and Mechanical Engineering Departments at UT Austin) published their initial findings in Nature.
The hydrogel is comprised of hydroxypropyl cellulose, konjac glucomannan (hydrophilic powder made from the konjac plant), and lithium chloride. And, that gel can be molded into various configurations- in about two minutes time. The gel is then freeze-dried and peeled away from the mold. And, lo and behold, the hydrogel is then capable of sucking water right from the air.
The water (about 87% of what has been absorbed in a cycle- of about an hour) is released within 10 minutes when heated to 60C (140F). Moreover, the hydrogel can repeatedly function for 14 to 24 cycles a day, depending upon the relative humidity in the air. (15% humidity affords 5.8 L (1/5 gal) of water a day; when the humidity is 30%, that collection is 13.3 L (3.5 gal) a day).
While DARPA plans to use this to supply water for our troops, there are plenty of civilian uses for this hydrogel.
