Abstract: A process for producing carbon dioxide from a gas stream containing same pretreats the incoming raw gas to remove contaminants and particularly to protect degradation of the membranes utilized for separation. The temperatures of the various gas streams are carefully controlled to reduce water from the stream. By-product and other gas streams of the process are recycled in order to increase efficiency by utilizing the heating or cooling properties of the streams. In addition, streams containing minor portions of carbon dioxide are returned to the system for recovery.

Abstract: An open pore liquid purification apparatus containing semipermeable membranes, is made by: (1) placing a module, made of bonded, resin coated filler particles, having a plurality of spaced circular bores therethrough, in a stationary vertical position, (2) placing a viscous casting composition into each of the bores, the composition containing 10 parts polysulfone resin and 10-40 parts of an organic solvent, the solvent being effective to homogeneously disperse and partly dissolve the polysulfone, (3) gravity dropping a casting bob, having a circular cross-section at its widest point, down through each bore to form a continuous film of casting composition on the inside of each bore, and then (4) immediately exposing the film to a low humidity atmosphere, and (5) contacting the film with a suitable leaching liquid, to form a polysulfone ultrafiltration membrane on the inside of each module bore; the membrane being resistant to solvents and operable at a pH of about 1 to 12 and a temperature of about 5.degree.