Gas separation and purification by means of membrane processes.

Until today the main application of membranes on a large industrial scale has been the separation of aqueous solutions. More recently, however, membranes have also gained increasing commercial importance for the separation of certain gas mixtures. Another interesting application is the recovery of organic vapors from waste air steams. In this case membranes can compete favourably with conventional processes. In this paper the development of a synthetic membrane suitable for the separation of organic vapors from waste air is described. Parameters determining the membrane properties in terms of permeability and selectivity are discussed and criteria for the selection of suitable materials and techniques for manufacturing these membranes are described. The successful use of membranes in gas and vapor separation is illustrated in a practical example.