Since nitrous is denser than air, and carbon dioxide is denser than nitrous, would it be possible to create relatively simple nitrous recycling system?

Starting with an open-top but otherwise airtight cylinder big enough to contain several liters of air, introduce a big percentage of its capacity with nitrous via a tube at the bottom, displacing the air above and creating a pocket of nitrous. One could inhale from the top half of the container via another tube installed there, and exhale into another tube installed at the very bottom; inhaling regular air between hits, but exhaling into the container until all nitrous is out of the body.

In theory, the inhaled air should simply rise to the top and keep the nitrous section trapped, and the carbon dioxide should sink to the bottom. Granted this would displace the nitrogen, but carbon dioxide could be leaked out the of bottom every so often.

I think it’s possible, but would cost more in research and development than would be worth it.