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/m.sup.2/day, the outer diameter of the hollow fiber type semipermeable membrane is 100 to 350 m, the inner diameter thereof is 50 to 250 m and the hollow ratio thereof is 24 to 51%.

The invention relates to membranes, membrane modules, and applications therefor. In particular, the invention relates to the construction of membranes for use in osmotically driven membrane processes.

An environmentally friendly closed loop manufacturing process (10.sub.1, 10.sub.2) produces microporous membranes (32) by cast or extrusion of polymer-plasticizer mixtures followed by non-porous film formation (20), extraction (22) of the plasticizer using an azeotrope solvent and thereby forming a solvent-laden sheet and a mixture of plasticizer and azeotrope solvent, distillation (28) of the mixture to separate the plasticizer and azeotrope solvent for reuse, evaporation (30) of the azeotrope solvent from the solvent-laden sheet to form the micropores, and capture of the resultant solvent vapor for subsequent adsorption-desorption of the azeotrope solvent from activated carbon (34) or by vapor condensation (36) for reuse in the manufacturing process. The azeotrope solvent is at least a two-component mixture of solvents, one of which is designed for efficient removal of the plasticizer, while the other component(s) render(s) the azeotrope solvent non-flammable.

A process for the preparation of ultrafiltration and microfiltration polymeric flat sheet separation membranes is disclosed, the process comprising a unidirectional cooling step. Membranes prepared according to the process exhibit numerous advantages over ultrafiltration and microfiltration membranes prepared via conventional processes. In particular, the membranes prepared by the present process exhibit remarkable pure water flux, superior mechanical properties and increased anti-fouling characteristics. Also disclosed are particular PVDF ultrafiltration and microfiltration membranes having improved flux, mechanical and anti-fouling properties.

Solution comprising a sulfone polymer and a N-acyl-pyrrolidine of formula I wherein R.sup.1 to R.sup.9 independently from each other are a hydrogen atom or a methyl group. The solution is applied in membrane formation with polyvinylpyrrolidone as optional component.

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A method for producing a gas separation membrane, including the following steps: step(a): treating the surfaces of silica nanoparticles dispersed in a first solvent with a reactive functional group-containing compound, while nanoparticles are being dispersed in the solvent, to thereby prepare a first solvent dispersion of reactive functional group-modified silica nanoparticles; step(b): replacing the first solvent dispersion's dispersion medium of reactive functional group-modified silica nanoparticles prepared in step(a) with a second solvent without drying of dispersion medium, and then reacting functional group-modified silica nanoparticles with dendrimer-forming monomer or hyperbranched polymer-forming monomer in the second solvent's presence so that dendrimer or hyperbranched polymer is added to reactive functional group, to thereby prepare dendrimer- or hyperbranched polymer-bound silica nanoparticles; step(c): mixing dendrimer- or hyperbranched polymer-bound silica nanoparticles prepared in step(b) with a matrix resin; and step (d): applying mixture prepared in step(c) to a substrate, and then removing the solvent.

The invention provides polymeric membranes with a mixed matrix and hollow fibers, with high mechanical resistance, useful in high pressure gas permeation processes such as, in particular, the removal of CO.sub.2 from raw streams resulting from oil exploration. The membranes are formed by at least one polymeric layer consisting of at least one polymer and an inorganic filler of clay mineral nanoparticles. The respective co-extrusion processes applicable to the production of said membranes are also provided herein.

Described are porous polymeric filter membranes made using poly(etheretherketone)-type polymers (PEEK), devices that include the PEEK membrane, and related methods of preparing and using the PEEK membranes.

The present invention relates to the development and fabrication of thin-film polymer composite materials containing vertically aligned nanopores. The present invention provides methods of aligning nanopores in a polymeric film. The present invention also provides composite materials and methods of fabricating composite materials containing vertically aligned nanopores.

A porous hollow fiber membrane includes at least a first solvent and a second solvent. The first solvent is at least one selected from sebacic acid esters, citric acid esters, acetyl citric acid esters, adipic acid esters, trimellitic acid esters, oleic acid esters, palmitic acid esters, stearic acid esters, phosphoric acid esters, C6-C30 fatty acids, and epoxidized vegetable oils. The second solvent is different from the first solvent, and is at least one selected from sebacic acid esters, citric acid esters, acetyl citric acid esters, adipic acid esters, trimellitic acid esters, oleic acid esters, palmitic acid esters, stearic acid esters, phosphoric acid esters, C6-C30 fatty acids, and epoxidized vegetable oils. The porous hollow fiber membrane has a three-dimensional network structure.