This invention discloses a hollow fiber membrane and its preparation method and application, belonging to the field of membrane separation. The preparation method adopts a spinning device with a triple-orifice spinneret, including the casting solution, bore fluid and outer solution. The bore fluid, casting solution and outer solution are respectively co-extruded from the inner, middle and outer orifice of the spinneret, respectively, to form the nascent membrane. The nascent membrane is immersed in external coagulation bath to form a hollow fiber membrane. The outer solution and bore fluid are weakly-polar non-solvents of membrane-forming material and are water soluble. Based on the characteristics of the bore fluid and the outer solution, on the one hand, the mass exchange rate between solvents and non-solvents can be slowed down, the formation of dense skin is effectively avoided, and the surface porosity of the membrane is improved. On the other hand, the liquid film between solvents and non-solvents can finally dissolve in the coagulation bath without remaining in the hollow fiber membrane and spinning device. The hollow fiber membrane is prepared without double dense skins, and the surface porosity of the inner and outer surfaces of the hollow fiber membrane is improved, which is good for the improvement of membrane flux.

The present invention relates to a composite porous hollow-fiber membrane including a first layer and a second layer which each include a fluororesin-based polymer, in which the first layer has a columnar texture oriented in a longitudinal direction of the composite porous hollow-fiber membrane, the columnar texture has an average value v of a Raman orientation parameter calculated with the specific formula, and the second layer has a three-dimensional network texture and has an average surface-pore diameter of 5.0 nm to 5.0 μm.

A method is disclosed for forming a microporous membrane that incorporates an additive having low water solubility at the membrane's active surface from a precipitation fluid. The incorporated additive at the membrane's active surface can improve one or more of the membrane's hydrophilicity, wettability, anti-fouling behavior, blood compatibility, and stability over long periods of use or repetitive use. The microporous membrane with this modified active surface can be a hollow fiber, flat sheet, or other self-supporting shape. The microporous membranes can be used for membrane filtering or a solute and/or solvent exchange process, which involve contacting aqueous-based fluid or blood with the microporous membrane, such processes for dialysis, blood oxygenation, or blood separation filtering, or other processes.

A preparation method of a zeolite/polyimide composite membrane includes: synthesizing a zeolite-doped polyamic acid precursor casting solution by condensation polymerization synthesis; coating a substrate with the obtained casting solution, and obtaining a zeolite/polyamic acid composite porous membrane by non-solvent induced phase separation; and obtaining the zeolite/polyimide composite membrane by performing thermal imidization on the zeolite/polyamic acid composite porous membrane through gradient heating.

The present invention deals with a method for obtaining membranes in the form of hollow fibers with application in the field of carbon dioxide removal from natural gas. The aforementioned membranes are obtained by means of heat treatment of polymeric membranes. In this method, polymeric membranes are obtained by a phase-inversion technique by immersion-precipitation and are subsequently subjected to a heat treatment, that is, that the membranes effectively become precursor membranes of the heat treatment. The heat treatment process involves the optimization of the heating rate, temperature, and stabilization time variables, aiming at the improvement of the transport properties of the polymeric membranes. After the heat treatment, it becomes possible to use the membranes in separation processes of gases which operate at pressures greater than 30 bar, with selectivity for carbon dioxide (CO.sub.2).

The present invention relates to a hydrophilic polyimide including at least one type of building blocks [A-B] and [A-C], and represented by the formula -[A-B].sub.n-[A-C].sub.m— (I), wherein: the n-bracketed building blocks and the m-bracketed building blocks are randomly distributed over the polyimide chain; repeat unit A results from a monomer comprising two carboxylic anhydride moieties, repeat unit B is hydrophilic and results from a first hydrophilic monomer comprising two primary amine moieties and at least one further hydrophilic moiety different from the primary amines, and repeat unit C is hydrophilic and results from a second hydrophilic monomer comprising two primary amine moieties and at least one further hydrophilic moiety different from the primary amines; wherein: n and m represent independently an integer from 0 to about 1000; wherein n+m is an integer from about 10 to about 1000.

The present invention also relates to a porous membrane comprising the same, a method of producing the hydrophilic polyimide and the porous membrane, a liquid phase separation system comprising the porous membrane, and a liquid phase separation method.

A method for making a gas separation membrane comprises dissolving and mixing poly(ether-b-amide) (Pebax) copolymer and acrylate-terminated polyethylene glycol oligomers (PEGDA) in a solvent, casting the polymer solution into a mold, removing the solvent to form a film, adding a photoinitiator to the film and irradiating the film with ultraviolet radiation to induce crosslinking of the PEGDA in the film, producing XLPEGDA, and submerging the film after exposure in a crosslinking solution to form crosslinked Pebax (XLPebax) in the film, wherein the crosslinking solution comprises one of a diisocyanate, a diisocyanate derivative and a combination of a diiscyanate and a diisocyanate derivative.

A composite semipermeable membrane includes a porous supporting membrane and a separation functional layer, in which, in cross-sections having a length of 2.0 μm in a membrane surface direction, the average number density of projections in the separation functional layer which have a height of one-fifth or more of the 10-point average surface roughness is 10.0-30.0 projections/μm and the projections have an average height less than 100 nm, and in which a water production rate and a salt rejection are predetermined values or more after an aqueous solution is passed through under certain conditions.

Provided herein are methods of fabricating membranes using polymers with functionalized groups such as sulfone (e.g., PSf and PES), ether (e.g., PES), acrylonitrile (e.g., PAN), fluoride (e.g., pvdf and other fluoropolymers), and imide (e.g., extem) and ionic liquids. Also provided are membranes made by the provided methods.

Provided are: a porous polyether sulfone film having macrovoids and having excellent dimensional stability; and a production method therefor. Provided is a porous polyether sulfone film having a surface layer (a), a surface layer (b), and a macrovoid layer interposed between the surface layer (a) and the surface layer (b). The macrovoid layer has a partition wall joined to the surface layers (a) and (b) and a plurality of macrovoids surrounded by the partition wall and the surface layers (a) and (b). The surface layer (a) and the surface layer (b) have pores connected to the macrovoids.