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

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 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 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 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.