I'm working on a moon base for a project and I need to make air. I know that you can get oxygen and hydrogen by electrolysing water which is present in abundance on the moon. I need to mix nitrogen, oxygen and carbon dioxide to mimic the Earth's air. But I don't know how I'm going to get nitrogen and carbon there, on the Moon. I need to produce it in abundance (not so much as to fill an atmosphere, just enough to fill the base's building).
How should I do that?
Carbon dioxide is the easier of the two to acquire, but you'll need a system that is flexible and adaptive. The astronauts produce it as a biological function, albeit slowly. It was a problematic issue during the Apollo 13 rescue mission.
The initial atmosphere within the base could be composed of a different gaseous mix which changes over time - flexible and adaptive. Alternatively, the expensive option would be to initially send canisters of it from Earth to the Moon.
As people live on the Moon base they exhale carbon dioxide. This can be scrubbed, collected and stored to be utilized later.
As for nitrogen, a similarly slow process of accumulation could be implemented using biological plants or algae and nitrogenous fertilizers.
Supporting humans will require removal of CO2 they produce, not addition of CO2 from external sources. You will need it for agriculture, but the bulk of it can come from recycling organic waste. People will be living on imported food until agricultural production is capable of fully replacing it, so there will be plenty of that.
Nitrogen will pretty much have to be imported. The moon is also hydrogen-poor, so perhaps import most of it in the form of ammonia for agricultural and industrial uses. Any excess hydrogen you end up with can be combined with oxygen from regolith to make water.
The LCROSS impacts revealed the presence of methane, ammonia, and carbon monoxide and dioxide in a polar crater, so at least some of it could in theory be sourced from the moon. This will require mining ice in an eternally-dark polar crater, however, which will require mining, road-building, lots of machinery, etc, not to mention study to determine exactly what ices are available where and in what quantities.
