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

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 forward osmosis membrane based on interfacial hydrophilic modification, which comprises a separation skin layer on the surface, a porous support layer in the middle and a non-woven fabric support material at the bottom, and is characterized in that the porous support layer and the non-woven fabric There is also a hydrophilic polymer layer between the support materials, and the hydrophilic polymer layer is embedded in the non-woven support material. The material of the non-woven supporting material is polyolefin or polyester. The hydrophilic polymer can also be crosslinked by a crosslinking agent. The present invention, through hydrophilic modification, on the one hand reduces the osmotic resistance of water in the osmosis process and improves the water flux; on the other hand, in the process of phase inversion, because water is more permeable, it is easier to undergo instantaneous phase inversion , forming a large pore structure, increasing the porosity and reducing the tortuosity of the pores, so it can significantly reduce the internal concentration polarization and improve the water flux of the membrane.

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 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.