Use of aqueous, non-sweep liquid during membrane separation

Abstract

A material is separated from a fluid mixture by contacting the mixture containing the material with a first side of essentially solid, water-insoluble, hydrophilic, semi-permeable membrane in contact with an aqueous liquid barrier having ions which combine with the material to be separated to form a water-soluble complex. The partial pressure of the material on a second side of the semi-permeable membrane is sufficiently less than the partial pressure of the material in the mixture to provide separated material on the second side of the membrane. The separated material can be removed from the vicinity of the second side of the membrane by a gas stream. The second side of the membrane is contacted with an aqueous liquid medium to reduce the loss of the aqueous liquid barrier from the membrane which may otherwise decrease in separation efficiency during use due to water losses. The gas stream used to remove the separated material may be supersaturated with the aqueous medium, e.g. water, and may contact the membrane with the aqueous medium via condensation. Alternatively, the aqueous medium such as water may be applied by a continuous or intermittent film, spray or mist. The process is particularly useful for separating olefins, especially ethylene.