A raw material solution concentration system that has: a first unit for obtaining a concentrated raw material solution and a diluted induction solution by bringing a raw material solution containing a solvent and a solute into contact with an induction solution containing an induction solute through a forward osmosis membrane and transferring the solvent in the raw material solution into the induction solution and the induction solute in the induction solution into the raw material solution; and a second unit for performing a freeze-dry treatment on the concentrated raw material solution and obtaining a further-concentrated product.

A low cost, high selectivity asymmetric polyimide/polyethersulfone (PES) blend hollow fiber membrane, a method of making the membrane and its use for a variety of liquid, gas, and vapor separations such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO.sub.2/CH.sub.4, CO.sub.2/N.sub.2, H.sub.2/CH.sub.4, He/CH.sub.4, O.sub.2/N.sub.2, H.sub.2S/CH.sub.4, olefin/paraffin, iso/normal paraffins separations, and other light gas mixture separations. The polyimide/PES blend hollow fiber membrane is fabricated from a blend of a polyimide polymer and PES and showed surprisingly unique gas separation property with higher selectivities than either the polyimide hollow fiber membrane without PES polymer or the PES hollow fiber membrane without PES polymer for gas separations such as for H.sub.2/CH.sub.4, He/CH.sub.4, H.sub.2S/CH.sub.4, CO.sub.2/CH.sub.4 separations.

A low cost, high selectivity asymmetric polyimide/polyethersulfone (PES) blend hollow fiber membrane, a method of making the membrane and its use for a variety of liquid, gas, and vapor separations such as deep desulfurization of gasoline and diesel fuels, ethanol/water separations, pervaporation dehydration of aqueous/organic mixtures, CO.sub.2/CH.sub.4, CO.sub.2/N.sub.2, H.sub.2/CH.sub.4, He/CH.sub.4, O.sub.2/N.sub.2, H.sub.2S/CH.sub.4, olefin/paraffin, iso/normal paraffins separations, and other light gas mixture separations. The polyimide/PES blend hollow fiber membrane is fabricated from a blend of a polyimide polymer and PES and showed surprisingly unique gas separation property with higher selectivities than either the polyimide hollow fiber membrane without PES polymer or the PES hollow fiber membrane without PES polymer for gas separations such as for H.sub.2/CH.sub.4, He/CH.sub.4, H.sub.2S/CH.sub.4, CO.sub.2/CH.sub.4 separations.

Porous liquid-filtering membranes are provided having a boundary region substantially surrounding the pore region and having greater tear resistance than the pore region.

Porous liquid-filtering membranes are provided having a boundary region substantially surrounding the pore region and having greater tear resistance than the pore region.

Provided is a hollow fiber membrane that is excellent in water vapor separation performance immediately after production and water vapor separation performance after repeated use with compressed air. A hollow fiber membrane comprising a polyarylate resin, wherein the hollow fiber membrane includes a skin layer on at least one of inner and outer surfaces, has a tensile strength of 7 MPa or more and an elongation at break of 15% or more, and has an internal pressure water permeability of less than 100 L/(m.sup.2.Math.atm/h) as measured using pure water at 25° C.

Provided is a hollow fiber membrane that is excellent in water vapor separation performance immediately after production and water vapor separation performance after repeated use with compressed air. A hollow fiber membrane comprising a polyarylate resin, wherein the hollow fiber membrane includes a skin layer on at least one of inner and outer surfaces, has a tensile strength of 7 MPa or more and an elongation at break of 15% or more, and has an internal pressure water permeability of less than 100 L/(m.sup.2.Math.atm/h) as measured using pure water at 25° C.

Provided are a porous film having excellent surface smoothness and a method for producing the same. The surface roughness of a porous film of polyvinylidene fluoride, polyethersulfone, polyimide and/or polyamide-imide is Ra 30,000 Å or less. The opening diameter of the porous film is preferably from 100 nm to 5000 nm. The method for producing a porous film preferably includes a step for kneading a varnish containing fine particles and at least one resin selected from the group consisting of polyvinylidene fluoride, polyether sulfone, polyamic acid, polyimide, polyamide-imide precursor, and polyamide-imide. The varnish preferably has a viscosity at 25° C. of 0.1-3 Pa.Math.s, a solids fraction concentration of 10-50 mass %, and a fine particle average particle size of 10-5000 nm.

Provided are a porous film having excellent surface smoothness and a method for producing the same. The surface roughness of a porous film of polyvinylidene fluoride, polyethersulfone, polyimide and/or polyamide-imide is Ra 30,000 Å or less. The opening diameter of the porous film is preferably from 100 nm to 5000 nm. The method for producing a porous film preferably includes a step for kneading a varnish containing fine particles and at least one resin selected from the group consisting of polyvinylidene fluoride, polyether sulfone, polyamic acid, polyimide, polyamide-imide precursor, and polyamide-imide. The varnish preferably has a viscosity at 25° C. of 0.1-3 Pa.Math.s, a solids fraction concentration of 10-50 mass %, and a fine particle average particle size of 10-5000 nm.

Disclosed herein is a gas separation membrane comprising a furan-based polymer, an apparatus comprising the gas separation membrane, and a process for separating a mixture of gases using said gas separation membrane. The process comprises contacting one side of a gas separation membrane comprising a furan-based polymer with a mixture of gases having different gas permeances, whereby at least one gas from the mixture of gases permeates preferentially across the gas separation membrane, thereby separating the at least one gas from the mixture of gases.