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Sat Aug 25, 2018, 01:12 AM

Scientists create a mineral in the lab that captures carbon dioxide

Scientists are one step closer to a long-sought way to store carbon dioxide in rocks.

A new technique speeds up the formation of a mineral called magnesite that, in nature, captures and stores large amounts of the greenhouse gas CO˛. And the process can be done at room temperature in the lab, researchers reported August 14 at the Goldschmidt geochemistry conference, held in Boston.

If the mineral can be produced in large quantities, the method could one day help fight climate change.

“A lot of carbon on Earth is already stored within carbonate minerals, such as limestone,” says environmental geoscientist Ian Power of Trent University in Canada, who presented the research. “Earth knows how to store carbon naturally and does this over geologic time. But we’re emitting so much CO˛ now that Earth can’t keep up.”

Researchers have been seeking ways to boost the planet’s capacity for CO˛ storage. One possible technique: Sequester the CO˛ gas by converting it to carbonate minerals.

Magnesite, or magnesium carbonate, is a stable mineral that can hold a lot of CO˛ naturally: A metric ton of magnesite can contain about half a metric ton of the greenhouse gas.

But magnesite isn’t quick to make — at least, not at Earth’s surface.

Another option is to try to make magnesite in the laboratory — but at room temperature, that can take a very long time.

Under very high temperatures, scientists can quickly create magnesite in the lab, using olivine as a feedstock. But that process uses a lot of energy, Power says, and could be very costly.

The problem with making magnesite quickly, Power’s team found, is that water gets in the way. “It’s difficult to strip away those water molecules,” Power says. “That’s one of the reasons why magnesite forms very slowly.”

To get around this problem, Power and his colleagues used thousands of tiny polystyrene microspheres, each about 20 micrometers in diameter, as catalysts to speed up the reaction. The microspheres were coated with carboxyl, molecules with a negative charge that can pull the water molecules away from the magnesium, freeing it up to bond with the carbonate ions.

Thanks to these microspheres, Power says, the researchers managed to make magnesite in just about 72 days. Theoretically, he adds, the microspheres would also be reusable, as the spheres weren’t used up by the experiments.

That result doesn’t mean the technique is ready for prime time, Power says. So far, the scientists have made only a very small amount of magnesite in the lab — about a microgram or so. “We’re very far away from upscaling,” or making the technology commercially viable.

At: https://www.sciencenews.org/article/lab-mineral-magnesite-captures-carbon-dioxide



A Magnesite mine in China. Can manufacturing the highly absorbent mineral help slow climate change?

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Reply Scientists create a mineral in the lab that captures carbon dioxide (Original post)
sandensea Aug 2018 OP
spinbaby Aug 2018 #1
Sinistrous Aug 2018 #2
eppur_se_muova Aug 2018 #3
Igel Aug 2018 #4
defacto7 Aug 2018 #5

Response to sandensea (Original post)

Sat Aug 25, 2018, 06:42 AM

1. You know what else captures carbon dioxide?

Trees!

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Response to spinbaby (Reply #1)

Sat Aug 25, 2018, 07:10 AM

2. And oysters.

And clams.
And when they die, they do not release the stored CO2 back into the atmosphere.

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Response to sandensea (Original post)

Sat Aug 25, 2018, 11:03 AM

3. There have been several business ventures which have claimed ...

to trap CO2 using solutions of calcium hydroxide, thus forming calcium carbonate.

Where does this calcium hydroxide come from ?

Why, by thermal decomposition (with evolution of CO2) of naturally occurring calcium carbonate, of course ! Thus we have a very expensive, energy-intensive system for, in effect, transporting CO2 from one point on the surface of the earth to another, while producing more CO2 in the process.

I don't see much to convince me this process is very different. Our principal source of magnesium is seawater, from which it is precipitated by adding -- wait for it -- calcium hydroxide ! Made from, guess what, naturally occuring calcium carbonate !

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Response to eppur_se_muova (Reply #3)

Sat Aug 25, 2018, 11:22 AM

4. In this case they're using olivine.

Which may alter the energy inputs necessary. If they could use solar, then there's even less CO2 emitted in order to sequester CO2.

I like the idea of fertilizing parts of the ocean to produce more photosynthetic algae in order to sequester organic compounds on the ocean floor. Sort of what led to oil formation in the first place. Then again, that typically also winds up sequestering calcium carbonate, and while that does pull carbon out of the oceans it'll eventually lead to not so much calcium dissolved in the sea water.

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Response to sandensea (Original post)

Sat Aug 25, 2018, 11:26 AM

5. How many millions of tons of CO2 go into the atmosphere

every year? Double that number to determine the amount of magnesite needed to stay even with present levels of CO2 and they've made a few micrograms. Then where would those multi-millions of tons of saturated magnesite go every year? In the backyard?

Hmmm, doesn't sound promising.

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