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Is there a safe chemical way to remove CO2 from air?
- I know that alkali metal hydroxides (column I and II metal hydroxides) can be used to absorb carbon dioxide (CO2) in an enclosed atmosphere, like in a space craft or submarine. However, they're corrosive and absorb water vapor. (1) Is there any commonly-available material that is not toxic/dangerous that will absorb CO2? (2) What is used in underwater rebreathers/CO2-scrubbers? Thanks.
Plants absorb CO2, of course, but they take up a lot of room and are slow, inefficient CO2 absorbers.
Most industrial CO2 scrubbers use chemicals that don't meet your criteria.
Monoethanolamine (MEA) is used to scrub carbon dioxide from gas streams, but it's corrosive and toxic in very
Ascarite II is a very efficient CO2 absorbent, but
nonfibrous asbestos covered with sodium hydroxide.
Potassium superoxide is an interesting possibility
for spacecraft and submarine CO2 scrubbing, since it regenerates oxygen as it reacts with carbon dioxide:
4 KO2(s) + 2 CO2(g) = 2 K2CO3(s) + 3 O2(g)
But it isn't common, and it is quite toxic.
Calcium hydroxide (mixed with a small amount of sodium and potassium hydroxides) is used in most underwater rebreathers. The reaction between the hydroxides and
CO2 is exothermic, and divers can tell from the warmth of the scrubber canister that the absorption reaction is
working. Failure of the canister lid can give the diver a mouthful of hydroxides- called a "caustic cocktail" in diving circles. It's apparently a memorable experience.
You can learn more about the construction
and chemistry of rebreathers here.
Carbon dioxide sequestration (U. S. Department of Energy)Climate Change Information Kit (United Nations Environmental Programme)Physico-Chemical Life Support Systems (The Mars Club)Regenerative Life Support: Carbon Dioxide Control (James Atwater)
Regenerative Life Support: Water Production (James Atwater)
|Details on several CO_2_ recycling technologies for life support systems, including lithium hydroxide absorption, molecular sieves, solid phase amines, and silver oxides.|
Author: Fred Senese firstname.lastname@example.org