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 small amounts. Ascarite II is a very efficient CO2 absorbent, but it's basically 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:
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.The U. S. Department of Energy maintains a site on CO2 removal technologies being considered to reduce global carbon emissions.
Author: Fred Senese firstname.lastname@example.org
Copyright © 1997-2010 by Fred Senese
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Last Revised 08/17/15.URL: http://antoine.frostburg.edu/chem/senese/101/inorganic/faq/print-co2-scrubbers.shtml