Oxygen, nitrogen, argon and other rare gases are recovered from the air by separation. The cryogenic method for accomplishing this was developed by Carl von Linde more than 100 years ago. The air is compressed, freed of vapour, dust and carbon dioxide and is refrigerated to extremely low temperatures. It is compressed to a liquid and separated by distillation into oxygen, nitrogen, argon and other noble gases.
Today, other physical methods are also used to separate and purify air components:
Separation: by means of membranes
Absorbtion: various components of air are absorbed onto a special material while others flow through without obstruction
Gases
