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Lithium hydroxide was used to remove exhaled carbon dioxide from breathing gas during the Apollo mission.

Is there any research done how to recycle used lithium hydroxide on the Moon? Separating the carbon dioxide from the lithium and splitting it by electrolysis into carbon and oxygen. So both the oxygen and the lithium hydroxide may be reused?

There seems to be very little lithium found in lunar samples, so recycling is the only way to avoid importing it from Earth.

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  • $\begingroup$ There are other methods to remove CO2 from the air $\endgroup$
    – ikrase
    Jul 11 '20 at 20:37
  • $\begingroup$ The fact that little lithium is found inthe Moonis actually irrelevant. Naturally occurring lithium anywhere is unlikely to be in the form of a highly soluble and reactive hydroxide. $\endgroup$ Jul 15 '20 at 12:16
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Lithium carbonate will decompose to lithium oxide and carbon dioxide on heating to around 1300 °C. Lithium oxide can then be reacted with water to make the hydroxide, or with hydrogen peroxide to make lithium peroxide (which releases oxygen as it absorbs CO2). Alternatively, you could react it with calcium hydroxide to produce lithium hydroxide and calcium carbonate, which can similarly be regenerated by heating to 825 °C.

There are now several alternatives for carbon dioxide scrubbing that can be regenerated, making the expendable lithium-based scrubbers largely obsolete except as emergency fallbacks. For example, the Shuttle used a solid amine system on some flights (with a LiOH system kept as a backup), and the Carbon Dioxide Removal Assembly on the ISS uses zeolite beds: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050210002.pdf

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