Sea Water Demineralization by Means of an Osmotic Membrane

An osmotic membrane has been developed for demineralizing saline brines such as sea water. The major attractions of the process from an economic standpoint are its simplicity and relatively low energy consumption. The membrane is capable of producing a flux of 5 to 11 gallons of 0.05% NaCl water per sq. foot per day from a brine containing 5.25% NaCl, under a pressure of 1500 to 2000 p.s.i.g. The membrane is fabricated from a casting solution of cellulose acetate and acetone, to which is added an aqueous magnesium perchlorate solution. Key operations in the membrane fabrication process include immersion of the membrane in ice water within a prescribed period after casting, and subsequent heating of the membrane.