Tue February 28, 2012 By:
Respected Madam,

Can we separate oxygen from carbon dioxide?

Expert Reply
Tue February 28, 2012
 It is possible to separate the carbon from the oxygen, but it is very difficult. This is because it is a stable atom, meaning the last electron shell is full. It is possible to separate it, but not on a large scale.
The easiest way is to feed it to a plant. It converts the carbon to carbohydrate which can then be carbonized by heat in the absence of air or by strong sulfuric acid. Oxygen is produced when light is present. 

Alternatively, you could heat CO2 over a catalyst of iron doped zeolite and hydrogen to produce water and ethylene. A nonthermal plasma applied to ethylene will generate carbon soot and recover the hydrogen. Electrolysis of water gives back the extra hydrogen and produces oxygen. (Hey! I didn't say it was efficient.) It might be useful to someone on Mars who has endless power in the form of a nuclear reactor and plenty of CO2 but not so much oxygen.
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