34results about How to "Reduce internal concentration polarization" patented technology

The invention discloses a novel composite forward osmosis membrane and a preparation method thereof. The preparation method comprises the following steps: coating a casting solution on a low-density non-woven fabric and carrying out phase inversion in a gel bath so as to obtain a porous supporting layer; and allowing an aqueous solution of polyamine and an organic solution of polyacyl chloride to react on the porous supporting layer to form an ultrathin separating layer so as to obtain the composite forward osmosis membrane with a three-layer structure consisting of a low-density non-woven fabric layer, the porous supporting layer and the ultrathin separating layer. According to the invention, through hydrophilic modification of the porous supporting layer and modification of the ultrathin separating layer on the surface, the thickness of the compact ultrathin separating layer is reduced, and water flux is improved. The novel composite forward osmosis membrane prepared in the invention can be used in the process of forward osmosis and has high membrane flux and a high retention rate.

The invention provides a preparation method of a thin-layer composite forward osmosis membrane. On the basis of maintaining the original advantages, the prepared forward osmosis membrane can effectively reduce the polarization of internal concentration difference so as to greatly improve the water flux, can greatly improve the compounding strength of a screen supporting layer and an interface polymerized cortex, can improve the durability of the forward osmosis membrane, prolong the service life and can solve the bottleneck problem of the forward osmosis application. Dopa and / or dopamine is adopted for chemically modifying and decorating a screen, so that not only can the original excellent supporting layer structure of the screen be maintained, but also the hydrophilia and reaction property of the screen can be improved, and the compatibility between the screen and the cortex can be improved. In addition, long chain / hyperbranched macromolecules and surface active agent are added to polyamine aqueous solution, so that not only can the quantity of active groups be increased, but also the space structure of the macromolecule can be enlarged, the complete pavement of the aqueous solution on the surface of the screen can be facilitated, the cortex completeness can be improved, and a purpose of adjusting the cross-linking structure of the cortex can be realized.

The invention discloses a forward osmosis membrane based on interface hydrophilic modification. The forward osmosis membrane comprises a separation peel layer arranged on the surface, a porous support layer arranged in the middle and a non-woven fabric support material arranged at the lower part. The forward osmosis membrane is characterized in that a hydrophilic polymer layer is also arranged between the porous support layer and the non-woven fabric support material, and is embedded into the non-woven fabric support material; the non-woven fabric support material is made of polyolefin or polyester. The hydrophilic polymer can also be interlinked through a crosslinking agent. The forward osmosis membrane has the advantages that through the hydrophilic modification, on the one hand, the permeation resistance of water in a permeation process is reduced, and the water flux is improved, and on the other hand, in a phase inversion process, the water can easily permeate, so that an instant phase inversion can be more easily generated; a large pore structure is formed; the porosity is improved; the sinuosity of pores is reduced, so that the inner concentration polarization can be obviously reduced; the water flux of the membrane is improved.

The invention belongs to the technical field of membrane separation, and particularly relates to a forward osmosis composite membrane based on a two-dimensional nano material and a macroporous substrate and a preparation method and application of the forward osmosis composite membrane. According to the composite membrane, a two-dimensional nano material is deposited on the surface of a macroporoussubstrate to serve as a middle layer, a polyamide separation layer is formed on the surface of the middle layer, and the composite membrane is obtained. The two-dimensional nano material middle layerin the composite membrane prevents polyamide from permeating into the macroporous substrate to damage the original macroporous and mutually communicated pore structure, reduces the mass transfer resistance, and effectively relieves the internal concentration polarization phenomenon in the forward osmosis process, thereby greatly enhancing the separation performance of the polyamide composite membrane and prolonging the service life of the composite membrane. The forward osmosis composite membrane can be widely applied to seawater desalination, juice concentration and other fields.

The invention discloses a preparation method of a polyethersulfone-based positive permeable membrane, and relates to the field of membrane separation. The method comprises the following steps: dissolving polyethersulfone and polyethylene glycol in a solvent; coating membrane casting fluid on a low-temperature glass plate; leaving the membrane casting fluid to stand on the glass plate, and enabling the membrane casting fluid to generate thermally induced phase separation; finally immersing the glass plate into water, and enabling the solvent to be removed. The prepared base membrane is prepared into a polyamide separating layer by an interfacial polymerization method, the base membrane is sequentially immersed into an m-phenylene diamine-aqueous solution of which the percentage by weight is 1.0-4.0wt% and a trimesoyl chloride-hexane solution of which the percentage by weight is 0.05-0.2wt%, and finally heat treatment is performed at 60 DEG C for 300 s so that the polyethersulfone-based composite positive permeable membrane is obtained. The polyethersulfone-based composite positive permeable membrane prepared by the method disclosed by the invention has high hydrophilicity and porosity, and besides, a fault surface adopts a perforated finger shaped structure. Tests on properties of the composite membrane indicate that the composite membrane prepared by the method disclosed by the invention has a high permeation flux and a high interception rate.

The invention provides a forward osmosis membrane using graphene / carbon nanometer tube film as a support layer and directly performing interface polymerizing on surface and a preparation method. The preparation method comprises the following steps of firstly, manufacturing a self-supported graphene / carbon nanometer tube film, paving a polyamine-chloride polyamide selecting layer on the self-supported graphene / carbon nanometer tube film by an interface polymerizing method, drying, and performing heat treatment, so as to obtain a composite forward osmosis membrane. The forward osmosis membrane has the advantages that the self-supported graphene / carbon nanometer tube film with excellent property and structure is used as a novel superthin support layer, so that on one hand, the carbon nanometer tube structure is similar to the graphene, the compatibility is good, and a macro material can be well formed; on the other hand, the carbon nanometer tube and the graphene are mutually intercalated, so as to promote multiple water molecules to enter between the graphene layers; the thickness of the support layer is greatly reduced, the polarizing of inner concentration is effectively decreased, the water flux is greatly increased, and the high-flux forward osmosis membrane is obtained.

The invention discloses a cellulose acetate forward osmosis film material. The cellulose acetate forward osmosis film material is a dissymmetric film, and is 20-150 micrometers in thickness and 55 to 90 percent in porosity. The cellulose acetate forward osmosis film material is made of cellulose acetate casting film liquid in a film scraping manner by adopting a film scraping machine; the content of cellulose acetate in the cellulose acetate casting film liquid is 5-40wt%, and the balance refers to macromolecule solvents. The cellulose acetate forward osmosis film material disclosed by the invention is suitable for being used in the forward osmosis process, is good in hydrophilcity and has a superthin structure; the porosity of a supporting layer is large; the connectivity of a hole structure is good; the internal concentration polarization can be effectively reduced; the compactness of a surface layer is good; the reject rate of univalency salt is high; small molecules such as trace suspended solids, bacteria and viruses in a water body can be effectively removed; the treatment efficiency is high and the operation cost is low.

The invention relates to a preparation method for a double-skin forward permeable membrane with aquaporin. The preparation method specifically comprises the following steps of: 1) preparing a base membrane; 2) preparing a layer-by-layer assembly composite membrane; 3) preparing phospholipid vesicle solution; 4) introducing aquaporin; and 5) preparing a biomimic film with aquaporin phospholipid, wherein proteoliposome with aquaporin prepared in the step 4 is spread to the surface of the composite film prepared in the step 2, and then a cross-linking agent is used to carry out cross-linking to complete the preparation. According to the preparation method, the double-skin forward permeable membrane with aquaporin is prepared by layer-by-layer assembly; the double-skin forward permeable membrane can effectively prevent solute from entering the composite membrane, thereby reducing inner concentration polarization effect, and obviously improving effective water flux of the forward permeable membrane; and the the double-skin forward permeable membrane can be applied to different fields such as water treatment, membrane separation and the like, and has a wide application prospect.

The invention relates to a forward osmosis membrane doped with inorganic / organic hybrid nanometer particles A-g-B, and particularly discloses a forward osmosis membrane comprising (i) a base membrane layer and the inorganic / organic hybrid nanometer particles A-g-B doped in the base membrane layer, and (ii) an optional substrate used for supporting the base membrane layer. The forward osmosis membrane has excellent properties such as good hydrophilicity, a high permeation flux, a high reject rate, excellent antibacterial properties, high strength, good stability, and capability of effectively reducing inner concentration polarization.

The invention discloses a cellulose triacetate / polyamide composite membrane and an application thereof. The composite membrane is built based on a cellulose triacetate porous membrane, a polyamide ultra-thin membrane is built by an interfacial polymerization method, and the cellulose triacetate porous membrane and the polyamide ultra-thin membrane are compounded to form the composite membrane. Thecomposite membrane organically combines the advantages of good hydrophily, pore structure, easiness in regulation, large water flux and the like of the cellulose triacetate porous membrane with the advantages of high salt rejection and the like of the polyamide ultra-thin membrane. The cellulose triacetate / polyamide composite membrane is low in raw material cost, long in service life and excellent in pollution resistance. A preparation method is simple in process, easy to operate, strong in universality, mild in condition and applicable to preparation of a nano-filtration membrane, a forwardosmosis membrane, a reverse osmosis membrane, a pressure delay osmosis membrane and the like.

The invention relates to a preparation method of a high-performance cellulose triacetate forward osmosis membrane. The preparation method comprises the following steps: (1) preparing membrane casting fluid which is prepared from cellulose triacetate, N-methylpyrrolidinone, acetone and lactic acid: adding the lactic acid into a binary mixed solvent of the acetone and the N-methylpyrrolidinone, performing ultrasonic treatment for 1-10min to ensure that the lactic acid and the binary mixed solvent are sufficiently and uniformly mixed, then adding a membrane material, namely the cellulose triacetate, controlling the temperature to 30-60 DEG C, and performing mechanical stirring for dissolving so as to obtain the uniform membrane casting fluid; (2) performing sufficient deaeration on the membrane casting fluid at 30-60 DEG C, and performing membrane scraping on a glass plate; (3) immersing the glass plate with a thin layer of the membrane casting fluid in a gel coagulation bath of 10-50 DEG C, performing phase separation and membrane formation, then soaking the glass plate in deionized reclaimed water for 3-8d, after surplus solvents are removed, taking out the glass plate, and performing natural airing so as to obtain the cellulose triacetate forward osmosis membrane. Compared with the prior art, the preparation method disclosed by the invention has the advantages that the technological process is simple, requirements on equipment are low, preparation conditions are easy to control, and besides, mass production is easy to perform.

The invention discloses a method for preparing an organic forward osmosis membrane. According to the preparation method, nanometer particles are added, and the preparation method comprises the specific steps of matching, stirring, standing still, coating and the like. The prepared organic forward osmosis membrane remarkably improves hydrophilia of the membrane, reduces internal concentration difference polarization, improves permeation flux, reserves a high retention rate, remarkably improves antimicrobial property, enhances strength of the membrane due to the nanometer particle size and is more practical.

The invention discloses a method for improving the water flux of a composite forward osmosis membrane. The method comprises the following steps: (1) putting a base membrane of a forward osmosis membrane into a water solution of an organic solvent and carrying out immersion treatment; (2) taking out the base membrane subjected to the immersion treatment and washing with clean water; (3) preparing aseparation layer on the base membrane through interface polymerization, so as to obtain a high-flux polyamide composite forward osmosis membrane. According to the method provided by the invention, the organic agent is used for immersing so that a pore wall of the base membrane becomes thin, a pore structure is changed and the sinuosity of a membrane pore is small; meanwhile, the porosity of the base membrane is improved and the quantity of large finger-shaped holes is also increased, so that structural parameters of the membrane are reduced and an inner concentration difference polarization phenomenon of the forward osmosis membrane is reduced; finally, the water flux of the composite forward osmosis membrane is improved. The method provided by the invention is simple and the operation iseasy to realize, so that the method is especially suitable for large-scale industrial production.

The invention discloses a preparation method of a renewable polyelectrolyte membrane for forward osmosis technology and a regeneration method thereof. Polydopamine is used for modification of polyethersulfone surface and a selection layer is formed, layer-by-layer self-assembly technology is used for growth of polyethyleneimine and polyacrylic acid on the surface of the selection layer, and a regeneration layer is formed. The polyelectrolyte membrane employs polydopamine as the selection layer, inner concentration polarization is effectively reduced, and risk of membrane pollution is reduced;after membrane flux of the polyelectrolyte membrane is reduced due to membrane pollution, hydrochloric acid can be used for cleaning the regeneration layer, and the self-assembly technology is used for recovering interception performance of the membrane; the electrolyte membrane has low energy consumption and high water recovery rate for treating waste water containing salt; the surface hydrophilicity of the membrane is good, and pollution resistance and corrosion resistance are good, and working life is longer.

The invention discloses an allophane silicon nanotube hybridized forward osmosis membrane. An allophane silicon nanotube serves as a modifying agent, is pre-dispersed in membrane casting liquid and is converted into a membrane through a phase, and then allophane silicon nanotube hybridized forward osmosis membrane is obtained through interfacial polymerization. The inner concentration polarization of the forward osmosis membrane is effectively reduced, and water flux of the forward osmosis membrane is improved. The forward osmosis membrane has high permeation flux and efficient selectivity.

The invention discloses a method for extracting lithium from salt lake brine by using a hollow fiber FO (forward osmosis) membrane. The method comprises the steps as follows: surface activity modification of a hollow fiber base membrane, preparation of the hollow fiber FO membrane through layer-by-layer self-assembly and FO concentration of salt lake brine for lithium enrichment. An assembly is prepared from the hollow fiber FO and applied to multistage processes such as concentration of the salt lake brine for lithium enrichment. The hollow fiber FO membrane prepared with the method has highsalt resistance and higher retention rate. The preparation technology of the base membrane is simple, low in cost, low in consumption of functional layer materials, convenient to operate and easy to control. A membrane polarized layer is high in charge density, wide in applicable brine salinity range and high in concentration multiple. The operation mode that a selection layer faces a low-concentration brine lithium extraction raw material liquid (FO mode) is adopted, old salt lake brine, a salt lake tedded composite salt solution and a concentrated solution at a multistage nanofiltration process section for lithium extraction from the salt lake brine are taken as extraction liquids, the energy consumption and the production cost are low, the lithium loss rate is small, and the membrane isstable in performance, easy to clean and long in service life.

The invention discloses a preparation method of a degradable forward osmosis membrane. The method comprises the steps that 1, vacuum-dried PHA homopolaymer or copolymer which has the volume crystallinity being 5-70% and PLA homopolaymer or copolymer which has the volume crystallinity being 5-60% at the ratio being 1:9-1:1 are physically mixed to form a mixture; 2, the mixture is injected into extrusion equipment with a heating device for fusion, then a melt blowing method is adopted for collecting melt-blowing non-woven fabric at the spinning temperature being 176-225 DEG C; 3, a casting solution is prepared; 4, the casting solution is applied to a PLA base material, and a bottom film layer is formed; 5, the bottom film layer is taken down from the PLA base material, and the degradable forward osmosis membrane is obtained. The formed forward osmosis membrane is a fully-degradable, healthy and environmentally-friendly ecological membrane; compatibility of the membrane and a supporting layer is significantly improved, internal concentration polarization is reduced, permeation flux is increased, the high rejection rate is reserved, the strength of the membrane is enhanced, and the membrane is more practical.

The invention discloses a composite forward osmosis membrane and a preparation method thereof. In the present invention, the casting solution is coated on the low-density non-woven fabric layer, and the porous support layer is obtained by phase inversion in the gel bath; then on the porous support layer, the polyamine aqueous solution reacts with the polyacyl chloride organic solution to form the ultra-thin separation layer, thereby obtaining a composite forward osmosis membrane with a three-layer structure comprising a low-density non-woven fabric layer, a porous support layer and an ultrathin separation layer. The invention reduces the thickness of the dense ultra-thin separation layer and improves the water flux through the hydrophilic modification of the porous support layer and the modification of the ultra-thin separation layer on the surface. The forward osmosis composite membrane prepared by the invention can be used in the forward osmosis process to obtain higher membrane flux and rejection rate.

The invention relates to a hydrotalcite-like composite forward osmosis membrane support layer and a preparation method thereof. The composition of the composite supporting layer includes a polymer body and hydrotalcite-like nanoparticle additive materials, and is characterized in that the hydrotalcite-like nanoparticle is highly dispersed in the polymer. The preparation method of the composite support layer comprises the steps of synthesizing and washing the hydrotalcite-like nanoparticles, mixing the hydrotalcite-like nanoparticles and polymers in an organic solvent, forming a film, and phase inversion. The hydrotalcite-like composite forward osmosis membrane support layer prepared by the present invention has higher porosity and hydrophilicity, and effectively increases the thermal stability of the support layer and the pore diameter of the support layer surface, and reduces the internal concentration polarization phenomenon , has important application prospects in the preparation of forward osmosis membranes.

The invention relates to a preparation method for a hydrophilic and hydrophobic interpenetrating polymer network nanofiber, a forward osmosis membrane taking the nanofiber as a supporting layer, and a preparation method for the forward osmosis membrane, belonging to the technical field of membranes. The preparation method for hydrophilic and hydrophobic interpenetrating polymer network nanofiber forward osmosis membrane comprises the steps: preparing hydrophobic polymer melt or solution and hydrophilic polymer melt or solution, then respectively pouring the two melts or solutions into different injectors or electrostatic spinning tubes, electrically spinning the two melts or solutions into hydrophilic and hydrophobic interpenetrating polymer network nanofiber by utilizing electrostatic spinning equipment; and then polymerizing a thin desalting skin layer on the hydrophilic and hydrophobic interpenetrating polymer network nanofiber supporting layer by adopting an interfacial polymerization technology, thus preparing a high-throughput hydrophilic and hydrophobic interpenetrating polymer network nanofiber forward osmosis membrane. According to the prepared forward osmosis membrane, the water flux is obviously improved, the chlorine resistance is enhanced, and the internal concentration polarization is reduced.

The invention discloses a preparation method of a double-cortex positive permeable membrane material employing attapulgite as a porous support material. The method comprises the steps of (1) attapulgite pretreatment; (2) preparation of a base membrane by employing the pretreated attapulgite as the porous support material; and (3) preparation of a double-cortex positive permeable membrane. The method has the advantages that the pore volume is increased after pretreatment of the porous support material; the base membrane of the porous support material forms more reticular structures after organic modification and dehydration condensation, groups of the porous support material have hydrophobicity and the water flux is greatly improved. The retention rate of cellulose triacetate is higher than that of cellulose diacetate, inner concentration polarization is reduced by double activation layers formed at two sides of the porous support material, the retention rate is increased, and the performance of the positive permeable membrane is greatly improved.

The invention discloses a method for improving the water flux of a composite forward osmosis membrane, which comprises the following steps: (1) putting the base membrane of the forward osmosis membrane into an aqueous solution of an organic solvent for soaking treatment; (2) soaking the base membrane of the forward osmosis membrane After the base membrane is taken out, it is cleaned with water; (3) A separation layer is prepared on the base membrane through interfacial polymerization, thereby obtaining a high-flux polyamide composite forward osmosis membrane. In the present invention, the pore wall of the base film is thinned by immersion in an organic solvent, the pore structure changes, and the tortuosity of the film pores becomes smaller. At the same time, the porosity of the base film is increased, and the number of large finger-shaped pores is also increased, thereby reducing the thickness of the film. The structural parameters of the forward osmosis membrane reduce the internal concentration polarization phenomenon of the forward osmosis membrane, and finally improve the water flux of the composite forward osmosis membrane. The method of the invention is simple, easy to implement, and is especially suitable for large-scale industrial production.

The invention belongs to the technical field of membrane separation, and specifically relates to a forward osmosis composite membrane based on two-dimensional nanomaterials and a macroporous substrate, a preparation method and application thereof. The composite membrane deposits two-dimensional nanomaterials on the surface of the macroporous substrate as an intermediate layer, and forms a polyamide separation layer on the surface, which is the composite membrane. The interlayer of two-dimensional nanomaterials in the composite membrane of the present invention prevents the polyamide from penetrating into the macroporous substrate to destroy its original macropore and interpenetrating pore structure, reduces mass transfer resistance, and effectively alleviates the internal concentration difference in the forward osmosis process Polarization phenomenon, thus greatly improving the separation performance of polyamide composite membrane, can be widely used in seawater desalination, fruit juice concentration and other fields.

The invention discloses a preparation method of a polyethersulfone-based positive permeable membrane, and relates to the field of membrane separation. The method comprises the following steps: dissolving polyethersulfone and polyethylene glycol in a solvent; coating membrane casting fluid on a low-temperature glass plate; leaving the membrane casting fluid to stand on the glass plate, and enabling the membrane casting fluid to generate thermally induced phase separation; finally immersing the glass plate into water, and enabling the solvent to be removed. The prepared base membrane is prepared into a polyamide separating layer by an interfacial polymerization method, the base membrane is sequentially immersed into an m-phenylene diamine-aqueous solution of which the percentage by weight is 1.0-4.0wt% and a trimesoyl chloride-hexane solution of which the percentage by weight is 0.05-0.2wt%, and finally heat treatment is performed at 60 DEG C for 300 s so that the polyethersulfone-based composite positive permeable membrane is obtained. The polyethersulfone-based composite positive permeable membrane prepared by the method disclosed by the invention has high hydrophilicity and porosity, and besides, a fault surface adopts a perforated finger shaped structure. Tests on properties of the composite membrane indicate that the composite membrane prepared by the method disclosed by the invention has a high permeation flux and a high interception rate.

The present invention relates to a forward osmosis membrane doped with inorganic / organic hybrid nanoparticles A-g-B, and specifically discloses a method comprising: (i) a bottom film layer, and doped in the bottom film layer Inorganic / organic hybrid nanoparticles A-g-B; and (ii) an optional forward osmosis membrane for supporting the substrate of the bottom membrane layer. The forward osmosis membrane of the present invention has excellent properties such as good hydrophilicity, large permeation flux, high rejection rate, excellent antibacterial performance, high strength, good stability, and can effectively reduce internal concentration polarization.

The invention discloses a preparation method of an organic forward-osmosis membrane. Nanoparticles are added in the preparation method; the preparation method specifically comprises the steps of proportioning, stirring, standing, coating and the like. The prepared organic forward-osmosis membrane allows the hydrophilicity of the membrane to be significantly improved, reduces the internal concentration difference polarization, improves the osmosis flux, retains high interception rate, and significantly increases the antibacterial properties; and because of the nano particle size, the membrane strength is also enhanced, and the organic forward-osmosis membrane is more practical.

The invention discloses a method for preparing an organic forward osmosis membrane. According to the preparation method, nanometer particles are added, and the preparation method comprises the specific steps of matching, stirring, standing still, coating and the like. The prepared organic forward osmosis membrane remarkably improves hydrophilia of the membrane, reduces internal concentration difference polarization, improves permeation flux, reserves a high retention rate, remarkably improves antimicrobial property, enhances strength of the membrane due to the nanometer particle size and is more practical.

The invention discloses a double-skin forward osmosis membrane, which is characterized in that it includes a porous support layer in the middle and ultra-thin skin layers on both sides, and a screen or non-woven support material is embedded in the middle of the porous support layer. The material of the porous support layer and the ultra-thin skin layer is triacetate fiber, diacetate fiber or a mixture thereof; the material of the support material is cotton, polyester or nylon. Its preparation method is to immerse the treated supporting material in triacetate fiber, diacetate fiber or their mixture casting solution, pull it out from the middle of scrapers on both sides, and form a double-skinned forward osmosis membrane by a phase inversion method. The advantage of the present invention is that the forward osmosis membrane with the double skin layer can effectively prevent solutes from entering the porous support layer, reduce the inner concentration polarization of the support layer, thereby obviously improving the effective water flux of the forward osmosis membrane.

The invention provides a forward osmosis membrane and a preparation method thereof. The forward osmosis membrane includes a support layer; the support layer is a blend of an ultrafiltration membrane, graphene oxide, and 0-2 generations of polyamide-amine. The forward osmosis membrane has a large water flux, and the interlayer spacing between graphene oxide layers is relatively stable, and it is not easy to fall off between layers, and it is not easy to fall off from the ultrafiltration membrane, and can adjust the interlayer spacing of graphene oxide. At the same time, the forward osmosis The membrane has a high interception capacity for both anions and cations in the solution, thereby improving the overall interception performance of the membrane.