Reusable encapsulated liquid sorbents rapidly capture CO 2
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sign, which would offer the efficiency and robustness of a liquid sorbent but that would have the lower toxicity and high surface area of a solid sorbhe need for effective carbon capture ent. Vericella and the rest of the team is at an all-time high. With over a wanted a material comprised of off-thebillion tons of CO2 produced by coalshelf ingredients so that scale-up would burning power plants each year, finding be feasible. “There’s a lot of carbon to a way to prevent that greenhouse gas capture,” says Vericella. “We will need from entering the atmosphere is a high buckets of this or train cars. It has to be priority. But capturing carbon is not alpractical.” The team turned to microfluways an easy task, especially not at the idics, specifically encapsulated liquid rate at which it is produced. An article sorbents. Microcapsules were an ideal published in the February 5 online edistructure because they would provide tion of Nature Communications (DOI: a large surface area while still being 10.1038/ncomms7124) reports a novel relatively inexpensive to produce. carbon capture material: encapsulated The microcapsules are comprised of liquid sorbents. several layers. In the middle lies aqueous “This is a very neat invention and repotassium or sodium carbonate. A zincverses the usual logic to decouple form based catalyst cyclen is incorporated in from function,” says Stuart Haszeldine, this interior core to speed up CO2 absorption. A second, outer layer is made professor of Carbon Capture and Storage of a liquid version of what will become at The University of Edinburgh, who is a solid shell, in this case silicone, which unaffiliated with the work. is highly permeable to CO2. The liquids Currently, liquid amine sorbents like are fed at different speeds through nested monoethanolamine are used for carbon glass capillaries, with the liquid sorbent capture. They are particularly useful bein an interior capillary. As the silicone cause they are resilient in humid places, flows out first, the liquid sorbent flows such as the flue of a coal factory, and have into the middle of the forming microcapa rapid uptake and high capacity for CO2. sule. The silicone liquid eventually encircles all of the liquid sorbent. When exposed to UV light, the silicone hardens and forms the shell. “The capsules are both highly permeable and highly selective,” says Vericella. The silicone exterior is permeable, allowing CO 2 through at a speed that doesn’t inhibit CO2 uptake. But the liquid core is highly selective, meaning CO2 is captured efficiently. With this combination, the microcapsule is capable of capturing CO2 at a rate comparable if not higher than traditional amine solvent methods, says Vericella, but without the drawbacks of toxicity and corrosion. The microcapsules were stable, even in wet environments, meaning they could be used directly in a Using nested glass capillaries, microcapsule layers are created at the same time, with UV exposure hardening flue to capture gas. the exterior, leaving the interior liquid. Credit: LLNL. Reusab
