There is currently no easy way to obtain oxygen other than from the air.
Suggestion:Electrolysis, Cryogenic Distillation, etc.

We also need a simple method to separate mixed gases. such as Adsorption.

If it does exist, please specify it in the JEI. Thank you!

Maybe cryogenic distillation was already a available method? Cooling a vat filled with air till oxygen liquefies, you can simply pump out pure oxygen as a liquid.

okay closed