Matthew D. Green’s work to develop high-efficiency, low-maintenance carbon dioxide removal systems, which are critical for human space missions beyond low Earth orbit, recently earned him an Early Career Faculty Award from NASA. Photographer: Erika Gronek/ASU
Matthew D. Green, an assistant professor of chemical engineering, wants to help space travelers breathe easier.
Astronauts inhale oxygen and exhale carbon dioxide when traveling in space just like on Earth. But on Earth, plant life absorbs exhaled carbon dioxide. When humans exhale carbon dioxide in a sealed environment, the oxygen level falls while the carbon dioxide level rises.
The Occupational Safety and Health Administration considers any atmosphere with an oxygen level below 19.5% to be oxygen-deficient and dangerous to humans. In enclosed environments, oxygen levels can get dangerously low if rising levels of carbon dioxide are not absorbed. High levels of carbon dioxide in these environments can be life-threatening.
Green received an Early Career Faculty Award from NASA’s Space Technology Research Grants to develop high-efficiency, low-maintenance carbon dioxide removal systems, which are critical for human space missions beyond low Earth orbit.
Currently, carbon dioxide is removed with solid sorbents made from materials that are unreliable, require frequent maintenance and may be a health hazard. Ionic liquids are another method for carbon dioxide removal due to their very low volatility or high stability. However, liquids in space tend to float away.
“This project will design new support polymers, processing polymers into large surface area membranes, loading them with carbon dioxide-selective ionic liquids and engineering their performance to improve carbon dioxide removal in microgravity environments,” says Green.
“The fibers of our filters will contain an ionic liquid (molten salt) that can selectively absorb carbon dioxide.”
He anticipates two phases of this project: the passive capture of carbon dioxide from the air and a continuous removal of carbon dioxide.
“The fibers of our filters will contain an ionic liquid (molten salt) that can selectively absorb carbon dioxide,” says Green. “As air passes over the filter, it will remove carbon dioxide. After some period of time, the carbon dioxide in the filter will have to be discharged.”
Green’s work with polymers impacts several areas, including consumer products, packaging, textiles, food additives, performance materials and membranes.
“Polymer technologies can provide solutions to today’s biggest engineering challenges, such as sustainable access to clean water and rising carbon dioxide concentrations,” says Green.