The present invention relates to the field of air filtration, in particular to a polytetrafluoroethylene composite filter material. The polytetrafluoroethylene composite filter material comprises a supporting layer and a polytetrafluoroethylene film layer, wherein the supporting layer is a silver-plated carbon nanomaterial-modified meltblown nonwoven fabric. The polytetrafluoroethylene composite filter material is prepared by fiberizing a resin material modified by silver-plated carbon nanomaterial on the surface of a polytetrafluoroethylene film by a melt-blowing method. The polytetrafluoroethylene composite filter material of the present invention combines filtering and sterilizing functions, has higher filtering efficiency and filtering precision, has the functions of sterilizing and killing viruses, has a good isolation effect, and greatly prolongs the service life of the filter material.

A separation membrane, suitably for oil and water separation. The membrane including a porous substrate layer and an active layer arranged over at least a part of the substrate layer. The active layer includes a hydrophilic agent and a superhydrophilic agent. Also described is a method of producing the separation membrane and a drain valve comprising the membrane.

A spunbond non-woven fabric includes a nonbonded projected part and a bonded recessed part. Bending resistance in a machine direction of the spunbond non-woven fabric is 20 mN or more and 40 mN or less, and in a non-woven fabric cross-section, a thickness from one surface to another surface of the projected part is determined to be t.sub.A, a thickness from one surface to another surface of the recessed part is determined to be t.sub.B, and respective distances from one surface of the projected part to one surface of the recessed part are determined to be t.sub.C and to (t.sub.C<t.sub.D), and the spunbond non-woven fabric has a relation represented by formulas (1) and (2) below:

0.5≤1−t.sub.B/t.sub.A<1.0  (1)

0.35<t.sub.C/t.sub.D<0.65  (2).

A nonwoven web obtained by electrospinning, suitable for the filtration of nano- and/or submicron aerosols, including a multiplicity of fibers of composition C1, the composition C1 including at least 50% by weight of at least one polymer P1 based on the repeat unit resulting from vinylidene fluoride (VDF), the fibers of composition C1 having a degree of crystallinity in polar phase(s), preferentially in solely beta phase, of at least 65% by weight, with respect to their total weight. Also, a process for the manufacture of the web, to a membrane including the web and also to a process for the washing/sterilization of the web or of the membrane.

A filtration filter for filtering out impurities has a support with a fibrous structure. A filtration membrane is integrally formed inside the support. The filtration membrane includes a porous resin and is capable of filtering out impurities. The filtration membrane includes a porous resin membrane having an average pore size of 0.026 μm and an opening ratio of 6% to 30%.

A method for preparing a nanofiltration membrane and a nanofiltration membrane prepared therefrom, the method comprising the following steps: dissolving a polymer in a solvent to prepare a polymer solution, and curing the polymer solution on a support material to form a base membrane; sequentially applying a first liquid-phase solution and a second liquid-phase solution on the base membrane to form a nascent membrane; densifying the nascent membrane by using a solution that contains an alkaline substance; processing the densified nascent membrane by using a solution that contains an acidic substance; and obtaining the nanofiltration membrane after post-processing and drying.

The present invention is related to an osmosis membrane, specifically to a modified forward osmosis membrane and the method of preparing same. The inventive forward osmosis membrane has a modified membrane structure including a hydrophilic support mesh and a hydrophilic polymer membrane layer mixed antioxidant. The hydrophilic polymer membrane layer with antioxidant not only has high salt rejection, but also ensures high oxidation resistance under a strong oxidation environment, and can be used safely and stably. The inventive oxidation resistant forward osmosis membrane has the advantages of improving the efficiency of purifying and separating water, extending the service life, significantly reducing the operation cost of the forward osmosis membrane system. The inventive forward osmosis membrane can be applied in the industries of treatment of strong oxidation waste water, water purifying, filtration and purification of food and medicine filtering and so on.

The forward osmosis membrane and the preparation method thereof provided by the present invention, through fully cover the support mesh layer of the membrane with antibacterial nanoparticles, especially the mixture of nano-Ag and nano TiO2, ensures without reducing the strength, water flux and salt rejection, providing an effective, long-term and comprehensive antibacterial effect. In the present invention, the antibacterial nanoparticles, especially the mixture of nano-Ag and nano-TiO2, are used to carry out antibacterial modification on the support mesh of the forward osmosis membrane, so as to inhibit the growth of bacteria on the forward osmosis membrane, improves the forward osmosis and also improves the safety of the entire purification and filtration system. The antibacterial forward osmosis membrane of the present invention can be applied to the filtration and purification of complex water sources, especially the purification and filtration of eutrophic and bacteria-prone water sources.

An anion-exchange membrane of the present invention includes a substrate made of polyolefin-based woven fabric and an anion-exchange resin, and has an electrical resistance measured using 0.5 M NaCl solution at 25° C. of 1.0 Ω•cm.sup.2 or more to 2.5 Ω•cm.sup.2 or less, a bursting strength of 0.7 MPa or more to 1.2 MPa or less, a water permeation rate measured using pressured water at 0.1 MPa of 300 ml/(m.sup.2•hr) or less, a thickness of the substrate of 90 .Math.m or more to 160 .Math.m or less, and an open area ratio of the substrate of 35% or more to 55% or less.

Provided are a polyimide compound including a repeating unit having an aromatic diamine component having a specific structure in which a side-chain benzylic position is regioselectively brominated, a gas separation membrane having a gas separation layer containing the polyimide compound, and a gas separation module and a gas separation apparatus each having the gas separation membrane.