Scientists at Weinberg College of Arts and Sciences at Northwestern University in Chicago have reported the development of a strong and reversible sponge-like material to capture and store gaseous carbon dioxide.
The main component, gamma-cyclodextrin, is a naturally occurring biorenewable sugar molecule that is derived from cornstarch. These sugar molecules are held in place by metals taken from salts such as potassium benzoate or rubidium hydroxide. It is the precise arrangement of the sugars in the crystals that causes them to capture of carbon dioxide.
Dr Jeremiah J. Gassensmith, lead author of the paper said that “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. 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.”
The researchers place an indicator molecule, which detects changes in pH by changing its color, inside each crystal. When the yellow crystals are full of carbon dioxide they turn red.
The simplicity, low cost and "greenness" of the process makes it a promising way of detecting and capturing carbon dioxide.