1160results about How to "Improve anti-pollution performance" patented technology

The invention relates to a preparation method of a polymer / graphene nano composite membrane, and aims to solve the problem that the existing polymer membrane material can not be applied in a large scale because the existing polymer membrane material is poor in hydrophilic property, is polluted easily and particularly is polluted by microbes and extracellular polymer easily. The preparation method disclosed by the invention comprises the steps of 1, taking a graphene nano material, a polymer, an organic solvent, an organic additive and an inorganic additive in parts by weight; 2, preparing a graphene nano material suspension; 3, preparing a membrane casting solution; 4, preparing a membrane by using the membrane casting solution in a coagulation bath medium to obtain a coagulation membrane, and then soaking the coagulation membrane in deionized water. The nano composite membrane disclosed by the invention is good in hydrophilic property, the irreversible pollution level of the nano composite membrane is significantly reduced, the anti-pollution capacity of the polymer membrane is effectively improved, the water flux is improved, and the polymer / graphene nano composite membrane disclosed by the invention is applied to the field of chemical industry.

The invention relates to a membrane separation technique and aims at providing an asymmetric ultra-hydrophilic / hydrophobic dual-property polymer membrane and a preparation method thereof. According to the asymmetric ultra-hydrophilic / hydrophobic dual-property polymer membrane, a base membrane is a flat sheet membrane or a hollow fiber membrane, one side of the base membrane is a hydrophilic side, the water contact angle of the hydrophilic side is not greater than 30 degrees, the other side of the base membrane is a hydrophobic side, and the water contact angle of the hydrophobic side is not smaller than 120 degrees. The prepared asymmetric ultra-hydrophilic / hydrophobic dual-property polymer membrane is of the type of the flat sheet membrane or the hollow fiber membrane and belongs to an ultra-micro filter membrane category, and the pore diameter range of the membrane is 0.01-2.0 microns. Therefore, the hydrophilic and hydrophobic properties on double sides are different, one side is hydrophilic, the other side is hydrophobic, and the asymmetric ultra-hydrophilic / hydrophobic dual-property polymer membrane shows asymmetric hydrophilic / hydrophobic properties and is a novel water treatment membrane.

The invention relates to spraying a process for fluorocarbon surface layer paint, which comprises the following steps of: (1) cleaning and grinding; (2) primer spraying; (3) finish spraying; and (4) fluorocarbon surface layer paint spraying. The aircraft skin processed by the process has strong stain resistance, and the easy cleaning property is obviously improved.

The invention discloses a high-strength antipollution layer composite reverse osmosis membrane and a preparation method thereof. The composite reverse osmosis membrane comprises a non-woven fabric layer, a porous supporting layer and a dense polyamide layer, wherein the PVA antipollution layer with high crosslinking degree, which is formed through high-temperature crosslinking after being coated with a PVA solution and a solution containing a crosslinking agent and a catalyst in turn, is arranged on the surface of the dense polyamide layer. The composite reverse osmosis membrane increases the acting force between the antipollution layer and the dense polyamide layer and improves the strength of the PVA antipollution layer by constructing the PVA antipollution layer with high crosslinking degree on the surface of the dense polyamide layer of the prior reverse osmosis membrane so as to improve the scour resistance, the dissolution resistance and the antipollution ability of the reverse osmosis membrane and prolong the service life of the antipollution composite reverse osmosis membrane. Moreover, the composite reverse osmosis membrane also has the characteristics of easy preparation and operation, high water permeability and high salt retardation rate.

The invention relates to an ultraviolet curing coating which is characterized in that the ultraviolet curing coating comprises 1-35 wt% of epoxy acrylate, 1-35wt% of urethane acrylate, 20-50wt% of polyfunctional acrylate monomer, 1-15wt% of additive and 1-10wt% of photoinitiator. The coating formed by ultraviolet curing coating obtained by adopting the technical scheme has the advantages of good pollution resistibility, easy cleaning, high strength, strong adherence, high toughness and difficult stripping.

The invention relates to a novel method for modifying the surface of a polysulfone ultrafiltration membrane, used for improving the pollution resistance of a separation membrane. In the invention, by using polysulfone as a surface modification basement membrane, a living radical is generated on the membrane surface with an ultraviolet initiator or a thermal initiator to further graft a hydrophilic monomer on the surface of the membrane, thereby finishing grafting modification to a polysulfone ultrafiltration membrane. The method is convenient to operate, efficiently inhibits generation of polysulfone main chain fracture and also keeps the interception performance of the ultrafiltration membrane. In the prepared ultrafiltration membrane, the hydrophilicity is obviously improved, and the pollution resistance is remarkably enhanced.

The invention discloses a chemical and ionic cross-linked alginate hydrogel flat membrane for filtration, which is designed and prepared aiming at the problems of poor stability, low mechanical strength, overlarge pores and the like of a pure ionic cross-linked hydrogel filtering membrane. According to the flat membrane, sodium alginate is used as a membrane forming substrate, a water-soluble compound is used as a pore-forming agent, and a chemical cross-linking agent and an ionic cross-linking agent are added, so that the sodium alginate is subjected to covalent bonding and ionic cross-linking to improve the stability of the membrane. The mechanical strength and the pore size of the membrane and the stability in an electrolyte solution are adjusted by changing the types and the proportions of the chemical cross-linking agent and the ionic cross-linking agent. The hydrogel flat membrane is prepared through a simple preparation process and is low in cost; no organic waste liquid is produced; the obtained hydrogel membrane can resist the pressure of 0.2-1 MPa and has a good application prospect in the separation field in which membrane pollution is easy to produce, such as oil-water separation, protein separation and biological sample filtration. The hydrogel flat membrane is directly discarded and can be fully degraded by microorganisms after being used, so that no environmental harm is caused.

The invention discloses a polyvinylidene fluoride hollow fiber film and a preparation method thereof. The polyvinylidene fluoride hollow fiber film comprises the following components by weight percent: 20-60% of polyvinylidene fluoride resin, 10-50% of organic pore-forming agent, 1-30% of inorganic pore-forming agent and 5-30% of solvent. The preparation method comprises the following steps: mixing, squeezing, cooling, stretching, extracting the organic pore-forming agent and the inorganic pore-forming agent, and thermally shaping. The obtained polyvinylidene fluoride hollow fiber film has the advantages of high strength, good performance, better hydrophilicity, simple preparation process and energy saving.

The invention relates to an absolute displacement measuring device, which solves the problems of a high component customized cost and a large signal processing difficulty in prior absolute displacement measuring devices. The absolute displacement measuring device comprises a standard grating, a scanning mask, a light source, an optical system, a photoelectric detector and a signal processing circuit, wherein the standard grating further includes an incremental code channel, an absolute code channel and n reference position code channels, the incremental code channel includes first shading stripes arranged along a measuring direction according to a first incremental cycle, the absolute code channel comprises patterns which includes absolute position information and are arranged along the measuring direction, each of reference position code channels comprises the shading stripes arranged in the measuring direction according to an incremental cycle, and the cycle is longer than that of the incremental code channel. Light rays emitted by the light source are illuminated on the scanning mask through the optical system by the standard grating, and the photoelectric detector can receive an absolute position signal, a reference position signal and a subdivision signal. The signal processing circuit is used for processing an optical signal received by the photoelectric detector so as to obtain position values.

The invention relates to a polyvinylidene fluoride hollow fiber membrane and a preparation method thereof, belonging to the field of chemical industry. The pore size of the membrane is 0.02-0.5 micrometers, the thickness is 0.2-0.5 millimeters, and the external diameter of membrane wires is 1-2 millimeters. A membrane making liquid comprises the following components in percentage by weight: 15-30% of polyvinylidene fluoride resin, 1-10% of hydrophilic polymer, 0.5-5% of functional polymer or polymer monomer, 0.1-5% of surfactant, 0.1-15% of inorganic or organic polymer pore-forming agent, 0.1-5% of nano additive and 40-71% of solvent. The preparation method of the polyvinylidene fluoride hollow fiber membrane comprises the following step of: effectively controlling the interfacial tension between the membrane making liquid and a solidifying liquid and the double diffusion permeation speed of the solidifying agent and the solution on the interface by properly adjusting the ratio of all components and using the surface moistening and dispersing actions of the surfactant, the dispersing and thickening actions of the pore-forming agent and the hydrophilic action of the hydrophilic substance. Thus, the hydrophilic polyvinylidene fluoride hollow fiber membrane with high permeability is prepared.

The invention discloses a compound reverse osmosis membrane with interpenetrating network desalting layer and a preparation method of the membrane. The desalting layer consists of a stereoscopic network which is formed by interpenetrating macromolecule nanogel and polyamide. The preparation method comprises the following steps of: pre-adding hydrophilic and / or oleophylic macromolecule nanogel with good dispersion into a solvent of solution A and / or B, preparing a water phase A solution containing m-phenylenediamine and / or p-phenylenediamine, preparing an organic phase B solution containing trimesoyl chloride, enabling the solution A and the solution B to fully contact on a porous support carrier for interface reaction, rinsing by using deionized water, carrying out moisturizing treatment by using glycerol, and drying. The compound reverse osmosis membrane disclosed by the invention has a sodium chloride removal rate of not less than 99% and a flux of not less than 25GFD (Geophysical Fluid Dynamics) under a pressure of 225psi; the microstructure and the charge property of the desalting layer can be regulated and controlled through the macromolecule nanogel so that the reverse osmosis membrane with high anti-pollution capability is prepared; and the compound reverse osmosis membrane can further be used for developing novel low-pollution reverse osmosis membranes.

The invention belongs to the technical field of membranes, and particularly provides an anti-pollution cyclodextrin-polymer composite nano-filtration membrane and a preparation method thereof. The cyclodextrin-polymer composite nano-filtration membrane is prepared by compounding a cyclodextrin-containing aromatic polymer functional cortex on a porous support membrane by virtue of an interfacial polymerization method. In the nano-filtration membrane, the porous support membrane is immersed in an oil-phase solution, in a cyclodextrin-containing aqueous-phase solution and in the oil-phase solution; and the cyclodextrin is loaded to the composite membrane functional cortex by virtue of interfacial polymerization, and the structure is stable. The preparation method has a simple operation process and mild reaction conditions; and by virtue of the annular cavity structure of the cyclodextrin and massive hydroxy carried by the cyclodextrin, the water flux, hydrophilicity and pollution resistance of the membrane are improved.

A preparation method of a high-performance PVDF composite ultrafiltration membrane with the surface loaded with a TiO2 thin membrane is provided. The invention is used for solving the problems of complex process, high membrane preparing cost, and difficult industrialized production existing in a conventional method for improving membrane hydrophilicity so as to improve membrane flux, anti-fouling performance and the like. The preparation method comprises the steps: 1, preparing a PVDF polymer membrane casting solution, and preparing an ultrafiltration basement membrane by an immersion-precipitation method; 2, preparing an auxiliary agent solution; 3, soaking the basement membrane in the auxiliary agent solution, taking out and swashing with water, and soaking in deionized water; 4, preparing a titania precursor solution; 5, immersing the basement membrane in the titania precursor solution, hydrolyzing a precursor, taking out and swashing with water, and thereby obtaining the high-performance ultrafiltration membrane with the surface firmly loaded with the TiO2 thin membrane. The method of the invention has the advantages of simple operation and low cost; and the obtained ultrafiltration membrane has large permeation flux, high rejection rate, strong hydrophilicity and outstanding anti-fouling performance. The preparation method is used for the membrane processing field.

The invention belongs to the technical field of composites, and discloses a polyvinylidene fluoride and metal-organic framework composite ultra-filtration membrane and preparation and application. The preparation method comprises the steps that MIL-100 (Fe) prepared through a hydrothermal method is ultrasonically dispersed in solvent, polyvinylidene fluoride and a pore-forming agent are sequentially added, stirring is conducted for 12-24 h to enable the added substances to be dissolved and blended to be uniform, and a membrane casting solution is formed; the membrane casting solution is defoamed and put on a support for membrane coating, staying of a coated membrane in the air is conducted for 30-60 s, the membrane is immersed into a coagulating bath for solvent exchange, and the polyvinylidene fluoride and metal-organic framework composite ultra-filtration membrane is obtained. The metal-organic framework material MIL-100 (Fe) is added to the composite ultra-filtration membrane, the hydrophily of the ultra-filtration membrane is improved, the separating capacity of the membrane is improved, the anti-pollution capacity of the ultra-filtration membrane is improved, the service life of the membrane is prolonged, and a good application prospect is achieved.

The present invention discloses a plant polyphenol modified polymer membrane as well as a preparation method and application thereof, in particular relates to the field of modified polymer membranes with anti-fouling properties. In the prior art, due to low surface energy of the polymer membrane, the polymer membrane is susceptible to contamination with proteins, oils and the like and causes a series of temporary or permanent pollution problems. The polymer membrane provided by the invention utilizes the super-strong adhesive ability of plant polyphenols and the coordination of polyphenols andmetal ions to build a hydrophilic coating on the surface of a hydrophobic polymer membrane. The polymer membrane provided by the invention has the advantages of simplicity, high efficiency, mild reaction condition and strong practicability. The controllable hydrophilic modification of a hydrophobic polymer can be realized by changing the conditions of the dip-coating time, the concentration of aplant polyphenol mixed solution, the pH, the temperature and the like, and a high permeation flux can be maintained in the course of cross-flow continuous work, so that the polymer membrane has a verygood application prospect in the field of water treatment. The invention also opens up an effective way, which is simple and easy to operate and has strong universality, for modification of polymer membranes under mild conditions.

The invention discloses a hydrophilic modification method of a PVDF ultrafilter membrane by the utilization of nano-TiO2 sol and belongs to the field of membrane separation technologies. According to the method, PVDF is used as the main high-molecular membrane preparation material. The hydrophilic TiO2 sol prepared in advance is added into a casting solution containing PVDF, an organic solvent and an additive, and the hydrophilic PVDF ultrafilter membrane is prepared by the utilization of a phase inversion method. By the adoption of the method, water contact angle of the prepared PVDF ultrafilter membrane can be reduced from about 85 degrees to about 60 degrees, and hydrophilicity of the PVDF membrane is obviously raised. Various substances concerned in the invention comprise, by weight, 10-25% of polyvinylidene fluoride (PVDF), 60-80% of a solvent for dissolving polyvinylidene fluoride, 1-10% of the TiO2 sol, and 0-10% of the additive, wherein the additive contains a mixture of anhydrous LiCl and PVP. Porosity of the prepared membrane is 50-80% and its membrane pore size is 0.01-0.2 micron. The method provided by the invention has a simple membrane forming technology, is convenient to operate, and is easy to realize industrial production. In addition, the prepared ultrafiler membrane has good hydrophilicity and high water flux, and has a wide application prospect.

The invention relates to a tubular nanofiltration membrane with a multi-layer structure and a preparation method thereof. The tubular nanofiltration membrane with the multi-layer structure is four-layered, and the four layers comprises a first layer, a second layer, a third layer and a fourth layer from inside to outside in sequence, wherein the first layer is a microfiltration supporting tube made from a carboxyl-contained fiber knitting tube which is filled with inorganic minerals; the second layer is a ultrafiltration layer formed by coating carboxyl-contained polymer on the outer surface of the first layer; the third layer is a nanofiltration layer made of polyamide formed by interfacial polymerization; and the fourth layer is a water loving layer forming covalent binding with the third layer. The tubular nanofiltration membrane with the multi-layer structure is obtained through the steps of forming functional layers from indie to outside in sequence, and stable chemical binding is formed among layers, so that the tubular nanofiltration membrane has excellent resistance to pressure and mechanical strength, and good water loving property, water permeability and antifouling ability; and moreover, the flux reaches more than 30 L / m<2>h, the removal rate of singlevalent salt is more than 30%, and the removal rate of bivalent salt is more than 95%.

The invention relates to a preparation method of a nano TiO2-modified PVDF (Polyvinylidene Fluoride) ultrafiltration membrane. The preparation method comprises the following steps of: preparing a membrane making liquid from 15-20 percent by mass of PVDF, 1-3 percent of pore-foaming agent, 1-4 percent of nano TiO2, 3-5 percent of surfactant and 70-80 percent of solvent, ultrasonically oscillating the membrane making liquid for 5-10 minutes, leaching and defoaming; scraping with a membrane scraping machine to form a liquid membrane, standing in the air for 20-60 seconds, soaking into a coagulation bath and coagulating the liquid membrane into an ultrafiltration membrane; and after the ultrafiltration membrane falls off, taking the ultrafiltration membrane out, soaking into distilled water and cutting according to required size for later use. A nano TiO2 hydrophilic monomer is arranged on the surface of the PVDF ultrafiltration membrane, sodium dodecyl sulfate serving as a surfactant is used simultaneously, and dispersion is performed by ultrasonically oscillating, so that agglomeration of nano TiO2 is reduced, nano TiO2 is quickly and uniformly distributed into the membrane making liquid, the hydrophilicity of the PVDF ultrafiltration membrane is enhanced effectively, the energy consumption is enhanced greatly, the anti-pollution capacity and pollutant intercepting performance of the membrane are enhanced, and the service life of the membrane is prolonged.

The invention discloses a method for preparing a contamination-resistant composite reverse osmosis membrane. The method comprises the steps of (a) preparing a polysulfone support membrane; (b) preparing an aromatic polyamide reverse osmosis composite membrane by using the polysulfone support membrane obtained in Step (a); and (c) grafting chitosan on the surface of the aromatic polyamide reverse osmosis composite membrane obtained in Step (b). According to the method for preparing a contamination-resistant composite reverse osmosis membrane, chitosan is grafted on the surface of the polyamide reverse osmosis composite membrane through a chemical treatment method, so that hydrophilicity of the surface of the membrane as well as the water flux of the membrane is improved; meanwhile, contaminations such as hydrophobic organic matters and transition metal ions can be prevented from being absorbed on the surface of the membrane, thereby greatly improving the anti-pollution capability of the membrane; in addition, chitosan has broad-spectrum antibacterial property, so that the resistance of the membrane against microbial contamination is improved.

The invention discloses a fluorine-silicon modified epoxy resin power paint, which comprises the following raw materials in percentage by weight: 20-60% of fluorine modified methacrylic acid epoxy resin, 5-40% of organic silicon resin, 0.1-2% of nano fumed silica, 10-50% of heat-resistant filler, 1-15% of heat-resistant paint and 0.5-3% of leveling agent. Compared with the prior art, the heat resistant performance and the pollution resistant performance of the coating made of the fluorine-silicon modified epoxy resin power paint are both improved, the coating can be used in the environment at the temperature of 500 DEG C, and static contact angle to water at normal temperature can reach 100 degrees; and additionally, the fluorine-silicon modified epoxy resin power paint has the advantages of simple processing technology, low cost, and bright and smooth appearance of the coating, and can be thinly coated.

The invention discloses a preparation method of a hollow fiber pipe in an overlay film, which comprises the following steps 1) preparing a high-molecular polymer, an organic solvent, an additive and a pore forming agent to a plurality of homogeneous casting solutions according to different proportions; 2) removing the PET fiber braiding tube surface spot objects; 3) using a modifier for modifying the PET fiber braiding pipe, fixing a circular pipe at high temperature; 4) using a multi-immersing multi-rolling (several primary immersing-technology in series) technology for cladding various homogeneous casting solutions to the internal and external walls of the PET fiber braiding pipe in order, carrying out a process of circular pipe heat fixing after each time of immersing and rolling, placing the obtained the composite braiding pipe in a gel bath for splitting the phase after the multi-immersing multi-rolling process is finished to obtain the hollow fiber pipe. According to the invention, the PET fiber braiding pipe is taken as a main body, the multi-immersing multi-rolling technology is used, the micro casting solution is coated to the internal and external walls of the braiding pipe, the anti-pollution capability of the braiding pipe can be improved, and a polymer coat layer is formed on the braiding tube surface which can ensure the effective porosity amount and interception effect of the hollow fiber tube.

The invention discloses a double-layer composite hollow fiber nano-filtration membrane and preparation method and special tool thereof, wherein the nano-filtration membrane comprises a selective separating outer sheath layer and a mechanical inner supporting layer; the selective separating outer sheath layer with the thickness of 10-10000 nm is provided with the membrane holes with the hole diameter of 0.5-2 nm, wherein the thickness of the mechanical inner supporting layer is 1-3mm; the selective separating outer sheath layer and the mechanical inner supporting layer of the double-layer composite hollow fiber nano-filtration membrane are respectively dissolved into the solvent through the high polymer of the selective separating outer sheath layer and the high polymer of the mechanical inner supporting layer. The invention can control the thickness of the selective separating outer sheath layer to be 10-100 nm, thereby greatly reducing the materials of the selective separating outer sheath layer and greatly lowering the cost. The invention effectively controls the internal / external diameter of the membrane, the effective hole diameter of the membrane, the hole rate and the hole diameter distribution by controlling the components of the liquid materials, the spinning condition, the condensing bath and the post processes so as to obtain the high effective separating membrane provided with the good hydrophilic performance, pollution proof and large water flux.

The invention relates to a method for preparing an anti-pollution polysulfone porous membrane by self-assembling immobilization of metal ions. According to surface electrical load properties of a membrane prepared from a polysulfone material, an amino-containing compound with high positive charge density and hydrophily is used as a modification material, the modification material is adsorbed by the surface of the polysulfone porous membrane under electrostatic interaction, through a large amount of amino groups of the modification material, the modification material and Cu<2+>, Zn<2+> or Ag<+> of an inorganic antibacterial agent undergo a coordinated complexation reaction, and the inorganic antibacterial agent is immobilized on the modification material molecule by complexation action so that the polysulfone porous membrane with good hydrophily and antibacterial activity is obtained. The prepared polysulfone porous membrane has hydrophily, antibacterial property and pollution resistance. The method has simple processes, does not need complex equipment and is suitable for industrial scale application. The porous membrane can be widely used in water treatment in the field of environment, chemical engineering, foods and medicine.

A disposable treatment article or disposable cleaning article that includes a hydrophobic nanoporous material. The disposable treatment or cleaning article is configured to contact and apply the nanoporous material to a surface. The nanoporous material is configured to form hydrophobic nanostructures on a surface upon the application of an activation stimulus. The nanostructures provide an anti-contamination benefit to the surface upon which the nanostructures are disposed.

The invention relates to a preparation method of a polymer / inorganic nano-material composite ultrafiltration membrane. The preparation method comprises the steps of firstly, taking polymer, a solvent, an additive and inorganic nano-composite material according to weight parts to prepare film casting liquid; then, putting the membrane casting liquid into the magnetic field, scraping the membrane, and solidifying; finally, taking the membrane out from coagulating bath, washing, soaking, and drying to obtain the polymer / inorganic nano-material composite ultrafiltration membrane. The preparation method has the beneficial effects that the inorganic nano-composite material with magnetism is synthesized; the nano-composite material transfers towards the surface of the ultrafiltration membrane in the membrane scraping process and the phase inversion process when being applied with the action of the applied magnetic field, so that the problem that when the ultrafiltration membrane is mixed with and modified by the inorganic nano-material, the nano-material is usually buried in the matrix, so that the hydrophilic modification effect of the nano-material can not be fully exerted can be solved. After the preparation method is adopted, the hydrophilia of the surface of the membrane is remarkably improved, and the contamination resistance of the membrane is improved. Furthermore, the preparation method is simple in operation technology and easy to implement.

The invention discloses a preparation method of a wrapped polytetrafluoroethylene ultra-micro filter tube membrane. A sintered or unsintered drown polytetrafluoroethylene membrane of which the aperture is 0.03-0.3micon and the thickness is 10-50micon is cut into polytetrafluoroethylene strip-shaped membranes which are 5-25mm in width; the membranes are wrapped on a porous support tube which resists a temperature of 300-500 DEG C and is corrosion resistant and organic solvent resistant; and the support tube wrapped with the prepared polytetrafluoroethylene membranes is sintered for 20-80s at the temperature of 300-400 DEG C so as to prepare the wrapped polytetrafluoroethylene ultra-micro filter tube membrane of which the aperture of a filtering layer is 0.01-0.05micon. The wrapped polytetrafluoroethylene ultra-micro filter tube membrane has the advantages of high porosity, small aperture, uniformity in filtering layer, blocking resistance, internal and external pressure resistance, capability of back washing and the like, and can be used in solid-liquid and gas-liquid separation with high viscosity, high solid content and high pollution in food concentration, waste penetration liquid treatment, oil-water separation, membrane biologic reactor and the like.

The invention discloses a polyvinylidene-fluoride hollow fibre membrane and a preparation method thereof. Calculated according to parts by weight, the polyvinylidene-fluoride hollow fibre membrane is mainly prepared by the following components: 15 to 25 parts of polyvinylidene fluoride, 50 to 80 parts of solvent, 1 to 3 parts of surfactant, 2 to 12 parts of polymeric additive, 1 to 8 parts of inorganic additive and 1 to 12 parts of modified blend. By utilizing the simultaneous action of two modes of organic blending and inorganic adding according to the polyvinylidene-fluoride hollow fibre membrane and the preparation method thereof, the hydrophilcity of the polyvinylidene-fluoride hollow fibre membrane is obviously improved, and the pollution resistance can be obviously reinforced; and the pure water flux of the polyvinylidene-fluoride hollow fibre membrane is further enhanced by selecting and regulating the raw materials and the mixture ratio of the modified blend and the inorganic additive so as to obtain the permanently hydrophilic modified polyvinylidene-fluoride hollow fibre membrane.

The invention relates to a hollow fiber ultrafiltration composite membrane composed of the components in the following weight percent: 15-25% of membrane material, 5-15% of pore-making agent, 55-75% of organic solvent and 5-10% of lithium chloride; the membrane material is a mixture of chitosan and one of polysulfone, polyether sulfone, polyacrylonitrile, polymethyl methacrylate, or cellulose triacetate, wherein the chitosan accounts for 1-5% of the total weight of the raw material, and the average molecular weight of chitosan ranges from 300,000 to 1,000,000; the pore-making agent is one of polyvinylpyrrolidone, polyethyleneglycol, or polyvinyl alcohol, or a mixture thereof; and the organic solvent is one of N-methyl-2-pyrrolidone, dimethyl fomamide, dimethyl acetamide, or dimethyl sulfoxide. The invention has good bioactivity, biocompatibility, anti-coagulation property and other properties.

The invention provides an external-pressure type charged hollow fiber nano-filtration membrane which consists of a support tube, an ultra-filtration layer, a nano-filtration separation layer and a charged modified function layer from inside to outside in sequence, wherein the support tube is connected with the ultra-filtration layer by an inorganic nano-particle net structure, the ultra-filtration layer is connected with the nano-filtration separation layer by an amido bond, and the nano-filtration separation layer is connected with the charged modified function layer by a carbon-carbon single bond. The external-pressure type charged hollow fiber nano-filtration membrane is good in performance and excellent in hydrophilcity, water permeability and antifouling property, the flux is more than 35L / m2h, the rate of removal for univalent salt is more than 40%, and the rate of removal for divalent salt is more than 97%. The invention also provides a preparation method for the nano-filtration membrane, and the method is simple in process, can realize continuous or batch production according to the actual requirements and is suitable for industrial application.

An external-pressure column type hollow fibre membrane assembly able to be flushed by gas features that the dedicated glass flushing part is arranged among membran fibres at bottom, and the height / diameter ratio of column, the length / diameter ratio of membrane fibre, and the filling density of membrane assembly are reasonably set up for normalizing the moving tracing of gas and water and the flowing state of two-phase stream and making the membrane assembly work in subcritical throughput region. Its advantages are high membrane throughput and less pollution to membrane.