From Appropedia

Oxygen is the chemical element with atomic number 8 and represented by the symbol O.

Oxygen is useful for cutting and welding etc. An oxygen en-richer uses zeolite to absorb the nitrogen from ordinary air it does this from 2-5 atmospheres when the pressure is released the absorbed nitrogen is given up. Most hospital oxygen sets cycle between 2 tanks containing the zeolite one being refreshed whilst the other is absorbing the nitrogen to leave oxygen. Zeolite the active element is sold for aquarium users to remove ammonia could it be used for this application ? I know that there are several different types of zeolite both natural and synthetic, its the spaces between the atoms which do the absorbing.