The present invention is directed to a method and a system for separating oxygen from air. A compressible air stream that contains oxygen is mixed in a substantially co-current flow with an incompressible fluid stream comprising an incompressible fluid in which oxygen is capable of being preferentially absorbed. Rotational velocity is imparted to the mixed streams, separating an incompressible fluid in which at least a portion of the oxygen is absorbed from other compressible components of the air stream. The compressible air stream may be provided at a stream velocity having a Mach number of at least 0.1.