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AssigneeToyobo Co., Ltd.
InventorsMichiko Shimizu, Toshiyuki Yagi, Shinobu Tokimi
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To provide a hollow fiber type semipermeable membrane which achieves both water permeability and salt rejection ability at high level, so as to conduct, with small membrane area, a water treatment utilizing concentration difference from liquid mixture of high concentration and high osmotic pressure. A hollow fiber type semipermeable membrane comprising cellulose acetate, characterized in that, between an aqueous solution of 25° C. having sodium chloride concentration of 35,000 mg/L and freshwater of 25° C. having sodium chloride concentration of 0 g/L at 0 MPa, the permeation flow rate flown from inner side to the outer side of the hollow fiber type semipermeable membrane is 60 to 180 L/m2/day, the outer diameter of the hollow fiber type semipermeable membrane is 100 to 350 μm, the inner diameter thereof is 50 to 250 μm and the hollow ratio thereof is 24 to 51%.
A hollow fiber type semipermeable membrane comprising cellulose acetate for forward osmosis treatment, characterized in that, when an aqueous solution of 25° C. having sodium chloride concentration of 35,000 mg/L and pressure of 0 MPa is flown into an outer side of the hollow fiber type semipermeable membrane having length of about 70 cm while freshwater of 25° C. having sodium chloride concentration of 0 g/L is flown into an inner side of the hollow fiber type semipermeable membrane and discharged at 0 MPa, the permeation flow rate is 60 to 180 L/m2/day, the outer diameter of the hollow fiber type semipermeable membrane is 100 to 350 μIII, the inner diameter thereof is 50 to 250 μm and the hollow ratio thereof is 24 to 51%, wherein a dense layer having a thickness of 0.1 to 7 μm is near the outer surface of the hollow fiber type semipermeable membrane, wherein said permeation flow rate is measured under such a condition that twice of the permeated water flow rate flown from the inner side to the outer side of the hollow fiber type semipermeable membrane utilizing the concentration difference as a driving force is equal to a flow rate flown into the outer side of the hollow fiber type semipermeable membrane and that the discharged flow rate from the inner side of the hollow fiber type semipermeable membrane is equal to 10% of said permeated water flow rate, and wherein the hollow fiber type semipermeable membrane exhibits a salt rejection rate of 98% or more.
Dependencies are inferred from the claim text.