Scientists Discover New Way to Remove Carbon Dioxide From Air

Saturday, October 26, 2019 - 13:46

Researchers from Massachusetts Institute of Technology (MIT) have developed a technique, based on passing air through a stack of charged electrochemical plates, in order to remove carbon dioxide from a stream of gas.

According to the SciTechDaily report, MIT postdoc Sahag Voskian, who developed the technique based on passing air through a stack of charged electrochemical plates during his Ph.D., and T. Alan Hatton, the Ralph Landau Professor of Chemical Engineering released the results in the journal Energy and Environmental Science.

The device is essentially a large, specialized battery that absorbs carbon dioxide from the air (or another gas stream) passing over its electrodes as it is being charged up, and then releases the gas as it is being discharged.

In operation, the device would simply alternate between charging and discharging, with fresh air or feed gas being blown through the system during the charging cycle, and then the pure, concentrated carbon dioxide being blown out during the discharging.

As the battery charges, an electrochemical reaction takes place at the surface of each of a stack of electrodes. These are coated with a compound called polyanthraquinone, which is composited with carbon nanotubes. The electrodes have a natural affinity for carbon dioxide and readily react with its molecules in the airstream or feed gas, even when it is present at very low concentrations.

The reverse reaction takes place when the battery is discharged — during which the device can provide part of the power needed for the whole system — and in the process ejects a stream of pure carbon dioxide. The whole system operates at room temperature and normal air pressure.

“The greatest advantage of this technology over most other carbon capture or carbon absorbing technologies is the binary nature of the adsorbent’s affinity to carbon dioxide,” explains Voskian. In other words, the electrode material, by its nature, “has either a high affinity or no affinity whatsoever,” depending on the battery’s state of charging or discharging.

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