Good Thinking

Aerogel quickly and cheaply purifies water – by turning it to steam

Aerogel quickly and cheaply pu...
Because the material is 90 percent air by volume, relatively little of it is needed
Because the material is 90 percent air by volume, relatively little of it is needed
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Because the material is 90 percent air by volume, relatively little of it is needed
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Because the material is 90 percent air by volume, relatively little of it is needed

By converting liquid salt water – or tainted water – into steam, it's possible to obtain pure, clean drinking water. Doing so could soon be cheaper and easier than ever, thanks to a newly developed material.

Created by postdoctoral student Shaobo Han at Sweden's Linköping University, the substance takes the form of an inexpensive and highly-porous aerogel composed mainly of cellulose (and air), to which an organic polymer known as PEDOT:PSS has been added.

Cellulose is the most abundant organic compound on Earth, and is the main component of plants' cell walls. PEDOT:PSS, on the other hand, is very good at absorbing the energy in sunlight – it's particularly well-tuned to sunlight's heat-carrying infrared spectrum.

In order to allow a thin sheet of the aerogel to float on the surface of polluted or salt water within an enclosed solar still, a buoyant layer of porous foam is added to its underside. Once in place, the gel then absorbs water from below, while absorbing solar heat from above. This causes the absorbed water to quickly heat up and turn to steam, at a rate that is reportedly four to five times higher than if the sun were simply heating the water directly.

The steam then condenses onto a plate located above the aerogel, forming into droplets of purified liquid water that trickle down into a collection trough. All of the salt or other impurities remain behind in the gel, which can be rinsed out and reused multiple times.

"We hope and believe that our results can help the millions of people who don’t have access to clean water," says Assoc. Prof. Simone Fabiano, who supervised the study.

A paper on the research was recently published in the journal Advanced Sustainable Systems. And for another recent example of a cheap but effective "solar steam generation" material, check out what scientists at the University of Maryland made out of burnt wood.

Source: Linköping University

9 comments
guzmanchinky
WOW! This is very cool. Would make a good survival tool as well...
James Savage
What would you rinse out the aerogel with? The purified water that you just made? And how often?
f8lee
guzmanchinky might have a point, though I guess a critical question is now much water can be generated per square meter.
HeroLund
Well, nice. However - as far as I know - distilled water may be very pure but lacks some minerals which make it good to drink for a longer period of time. With a few additives it can probably be made fully useful.
martinwinlow
f8lee - From https://en.wikipedia.org/wiki/Solar_still ... this device should produce beteen ~1.0 and 1.5 litres of water per day per m2 of collection area. So, if done on a permanent installation basis, a system using this technology would be enough to be a main supply of drinking/cooking water.
clay
For sure you'd have to add electrolytes back into that distilled water.. or you will get a pretty dry throat ;-)
buzzclick
>The steam then condenses onto a plate located above the aerogel...so how does the shadow of the plate above not interfere with the solar process, and does that mean this only works on sunny days? Makes me wonder if it produces enough clean water to be viable on a larger economic scale, or it's best as a smaller survival tool as guzman said.
IggyDalrymple
I've been purifying my drinking water for past decade with my $100 distiller but it is an occasional chore (every 2 or 3 months) cleaning the mineral scale that builds up on the walls of the vessel. I usually use vinegar to help dissolve the scale. Haven't yet tried making moonshine.
ljaques
Carry 6 square meters of aerogel + collector plates to provide survival water, guz? That's ambitious! ;)