Environment

"Nanojars" capture carbon dioxide dissolved in water

"Nanojars" capture carbon diox...
Researchers have developed "nanojars" that can capture carbonates and other pollutants in water
Researchers have developed "nanojars" that can capture carbonates and other pollutants in water
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Researchers have developed "nanojars" that can capture carbonates and other pollutants in water
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Researchers have developed "nanojars" that can capture carbonates and other pollutants in water
A molecular model of a "nanojar" with a carbonate ion trapped in the center
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A molecular model of a "nanojar" with a carbonate ion trapped in the center

Carbon dioxide in the atmosphere attracts most of the attention in environmental concerns, but much of that ends up in oceans, making them more acidic. Now scientists have created “nanojars” that can easily capture this and other pollutants from water.

These nanojars are molecules consisting of a copper ion, a pyrazole group and a hydroxide in repeating units, suspended in an organic solvent. When they encounter an ion with a -2 charge – which includes several major pollutants like chromate, arsenate, phosphate and carbonate – these molecules will wrap around the target, neutralizing it.

“We’ve shown that we can extract chromate and arsenate to below US Environmental Protection Agency-permitted levels for drinking water – really, really low levels,” says Gellert Mezei, a scientist on the project.

Afterwards, the nanojars can be removed from the water relatively easily, because the solvent floats on top of the water, forming a layer on the surface. Finally, once the nanojar solvent is removed from the body of water, a weak acid is all it takes to unravel the nanojars and release the trapped ions. These can then be disposed of safely or recycled into useful products.

A molecular model of a "nanojar" with a carbonate ion trapped in the center
A molecular model of a "nanojar" with a carbonate ion trapped in the center

These nanojars can be customized to target different ions as well. Using one pyrazole makes for nanojars that will go after whatever -2-charged ions are there, but using two bound by a propylene linker targets sulfate more strongly. Using two pyrazoles linked with ethylene binds better to carbonate, which is a particularly important pollutant.

When carbon dioxide in the atmosphere dissolves in water, like the ocean, it can form bicarbonate ions, too many of which can change the water chemistry and make it more acidic. That in turn wreaks havoc on the aquatic environment, messing with a whole range of biological processes and even dissolving some sea creatures. It can even contribute to further atmospheric emissions.

Finding ways to clean up these pollutants is important, but the team cautions that the nanojars are still in the very early stages of development. How they could potentially be scaled up for real-world use will be the subject of further work.

“Whether this process for removing carbon dioxide from water – and indirectly, the atmosphere – would be competitive with other technologies, that I don’t know yet,” says Mezei. “There are many aspects that have to be taken into account, and that’s a tricky business.”

The research was presented at the 2021 fall meeting of the American Chemical Society.

Source: American Chemical Society

2 comments
2 comments
aksdad
Actually carbon dioxide absorbed by the oceans isn't making them more acidic, it's making them less alkaline. It's an important semantic difference because seawater is alkaline, with an average pH of about 8.1, and nowhere close to acidic, which is a pH below 7. Despite the computer models projecting that ocean pH will decline because of absorbed CO2, the oceans are so vast that if it's happening, it can't be measured with any of the instruments deployed right now. All the observations of ocean pH show no global measurable trend of declining pH. Search for "NOAA/PMEL OA observations and data" to see for yourself. The obvious conclusion is that if it's actually happening, it's so slow that it will have little, if any, effect on ocean organisms that have numerous generations to adapt; contrary to all the claims from the bogus experiments where the researchers rapidly and dramatically changed the pH of the seawater which, as any aquarium owner knows, will cause serious problems with fish and corals in the tank.
ljaques
@aksdad, Your comment is most relevant to me right now. I just started reading "Unsettled?" by Steven E. Koonin. From the content in the introduction, I think I'll be seeing a lot of these semantic cheats by climate alarmists in the book. He aims to tell the actual science and show how that varies from the statements made by researchers/media/pols, then make some suggestions as to what realistic changes the people of the world can make under a realistic budget, if any. (Obama's old science guy is closer to a denier (horrid term) than an alarmist. I love it.)