Edible sponge captures and stores carbon dioxide


September 26, 2011

The Northwestern filter changes color when full of carbon dioxide, then changes back after being emptied

The Northwestern filter changes color when full of carbon dioxide, then changes back after being emptied

As concerns continue to rise over man-made carbon dioxide entering the atmosphere, various groups of scientists have begun developing filters that could remove some or all of the CO2 content from smokestack emissions. Many of these sponge-like filters incorporate porous crystals known as metal-organic frameworks (MOFs). Unfortunately, most MOFs are derived from crude oil, plus some of them contain toxic heavy metals. Researchers from Illinois' Northwestern University, however, recently announced that their nontoxic MOF sponge - made from sugar, salt and alcohol - is fully capable of capturing and storing CO2. As an added bonus, should you be really hungry, you can eat the thing.

The main ingredient in the edible MOF is gamma-cyclodextrin, which is a biorenewable naturally-occurring sugar derived from corn starch. Metals taken from salts such as potassium benzoate and rubidium hydroxide hold the sugar molecules in place, those molecules' precise arrangement within the crystals being essential to the capture of CO2.

"It turns out that a fairly unexpected event occurs when you put that many sugars next to each other in an alkaline environment - they start reacting with carbon dioxide in a process akin to carbon fixation, which is how sugars are made in the first place," said postdoctoral fellow Jeremiah J. Gassensmith. "The reaction leads to the carbon dioxide being tightly bound inside the crystals, but we can still recover it at a later date very simply."

Not only can the filters be emptied of CO2 and reused, but they also have a way of letting people know when they can't hold any more. Each crystal has an indicator molecule placed inside of it, which changes color according to the surrounding pH. When the whole sponge changes from yellow to red, that means that it has reached capacity. After being emptied, its color returns to yellow.

The Northwestern research was recently published in the Journal of the American Chemical Society.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth

If it is a more cost effective method of collecting CO2 for use or sale good, but stop with the nonsense about AGW.


Sounds promising and with the paralysis by the world's largest emitters about doing anything concrete about their emissions, our only choice will be sequestration. I hope someone is working on a method for methane, as well.


That sounds good, but using sugar and alcohol to make those filters will also withdraw nutrition from the world food market. So I hope the filters taste really, really good.


How about putting this sponges to the mufflers of cars....could it be??

Carl Nierves
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