11 results about "Immersion precipitation" patented technology

The invention relates to a method for synergistically regulating and controlling the aperture of a material separation membrane based on electric field-vacuum heating, which comprises the following steps: S1, uniformly mixing polysulfone, an additive and a solvent, and preparing a supporting layer membrane casting solution; s2, coating the surface of a polyolefin-based microfiltration membrane with the supporting layer membrane casting solution obtained in the step S1, and preparing a polysulfone ultrafiltration base membrane through immersion precipitation phase inversion; s3, uniformly mixing sulfonated polysulfone, N, N-dimethylformamide, ethylene glycol monomethyl ether and a pore-preserving agent to prepare a sulfonated polysulfone separation layer membrane casting solution; and S4, coating the surface of the polysulfone ultrafiltration base membrane obtained in the step S2 with the sulfonated polysulfone separation layer membrane casting solution obtained in the step S3, applying a direct-current electric field perpendicular to the surface of the membrane, and simultaneously performing vacuum heating to obtain the material separation membrane. An electric field and vacuum heating synergistic technology is adopted to induce oriented arrangement of sulfonated polysulfone to form an ordered structure, the membrane pore size and the membrane structure consistency are accurately controlled, and the membrane permeation flux and separation selectivity are optimized.

The invention belongs to the technical field of high polymer materials, and particularly relates to a polyimide composite film as well as a preparation method and application thereof. The polyimide composite film is prepared from composite slurry containing polyimide, nanocrystalline cellulose and a polar aprotic solvent, the mass fraction of the nanocrystalline cellulose is 0.3%-0.7%, the mass fraction of the polyimide is 10%-20%, and the mass fraction of the polar aprotic solvent is 79.3%-89.7%. The preparation method comprises the following steps: preparing the nanocrystalline cellulose, synthesizing a polyamide acid solution, mixing the nanocrystalline cellulose and the polyamide acid solution to prepare composite slurry, and finally preparing the composite membrane by an immersion precipitation phase inversion method. The composite membrane has precise molecular weight cut-off, and meanwhile, the hydrophilicity, the mechanical strength and the anti-pollution performance are remarkably improved. The composite membrane can be directly used for intercepting macromolecular pollutants in sewage treatment or used as a supporting layer of a composite nanofiltration membrane, and the problem that the performance of a traditional separation membrane material is difficult to consider is solved.

The application relates to the technical field of photocatalysts, and discloses a BiOCl nanosheet doped PVDF composite film and a preparation method thereof. The preparation method of the nanosheet doped PVDF composite film is as follows: the nanosheet is surface-modified by using an alkenylated catechol type quaternary ammonium salt modifier to obtain an alkenylated nanosheet, wherein the nanosheet is any one of a BiOCl nanosheet, a Ni-BiOCl nanosheet and a Co-BiOCl nanosheet; a carbon-carbon double bond is formed through a dehydrofluorination reaction by alkali treatment to obtain modified PVDF powder; under the action of an initiator, the alkenylated nanosheet and the modified PVDF powder are subjected to a free radical polymerization reaction to obtain a composite film material; the composite film material is added into N,N-dimethylacetamide to form a casting solution; the casting solution is laid on a glass plate and is subjected to blade coating; and a nanosheet doped PVDF composite film is prepared through an immersion precipitation phase inversion method; and the film product can degrade methyl orange dye.

The invention relates to the technical field of reverse osmosis composite membranes, in particular to a high-temperature-resistant reverse osmosis membrane and a preparation method thereof. According to the method, basalt nanoparticles (10-1000 meshes) are added in the process of preparing a polysulfone base membrane, and the mixed matrix base membrane containing basalt powder is prepared through an immersion precipitation phase inversion method. The basalt comprises the following main chemical components: silicon dioxide (SiO2), aluminum oxide (Al2O3), iron oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), and a small amount of potassium oxide (K2O) and sodium oxide (Na2O). A water-phase monomer and a multi-acyl chloride oil-phase monomer are subjected to an interfacial polymerization reaction to prepare a polyamide functional layer, and a byproduct hydrogen chloride (HCl) generated in an interface process can reduce the crosslinking degree of the polyamide layer. Basalt nanoparticles are added into the base membrane and can be subjected to a neutralization reaction with a byproduct hydrogen chloride, so that the crosslinking degree of the polyamide layer is improved. Meanwhile, the basalt nanoparticles are porous materials and can provide a water channel in water-salt mass transfer, so that the water flux of the reverse osmosis membrane is improved. And finally, the basalt nanoparticles have the characteristics of high temperature resistance, high hardness, high strength, good wear resistance, large anti-slip coefficient, strong binding power with polysulfone and the like, and the high temperature resistance of the prepared mixed matrix basement membrane is obviously improved.

The application belongs to the field of membrane separation technology, and discloses a preparation method of a hydrophilic composite membrane. The hydrophilic composite membrane is a flat sheet membrane or a hollow fiber membrane, and comprises a support layer and a separation functional layer, wherein the support layer is located below the separation functional layer; the separation functional layer is a polydopamine separation membrane containing uniformly dispersed nanoparticles, and the mass percentage of the nanoparticles in the total solid content of the separation functional layer is 0.01-1%. The organic composite membrane has not only good separation selectivity, but also good anti-pollution performance. In addition, during the membrane preparation process, dopamine hydrochloride and inorganic nanoparticles are added into a gel bath, and the two are uniformly dispersed when ultrasonic mixing is performed, and then the immersion precipitation phase inversion method is adopted to prepare the polydopamine high polymer composite membrane modified by the nanoparticles. The membrane preparation process is simple, the permeation flux is large, the hydrophilicity is high, the service life can be significantly improved, and the cleaning cycle can be prolonged.

The invention relates to the technical field of photocatalysts, and discloses a BiOCl nanosheet doped PVDF composite membrane and a preparation method thereof.The preparation method of the nanosheet doped PVDF composite membrane comprises the steps that a nanosheet is subjected to surface modification through an alkenylation catechol type quaternary ammonium salt modifier, an alkenylation nanosheet is prepared, and the nanosheet is any one of a BiOCl nanosheet, a Ni-BiOCl nanosheet and a Co-BiOCl nanosheet; performing dehydrofluorination reaction through alkali treatment to form carbon-carbon double bonds, so as to prepare modified PVDF powder; carrying out free radical polymerization reaction on the alkenylated nanosheets and the modified PVDF powder under the action of an initiator to prepare a composite membrane material, and adding the composite membrane material into N, N-dimethylacetamide to form a membrane casting solution; spreading the membrane casting solution on a glass plate, scraping the membrane, and preparing the nanosheet doped PVDF composite membrane through an immersion precipitation phase conversion method, and the membrane product can degrade methyl orange dye.

A filtration membrane comprising a hydrophobic host polymer and a polymeric additive dispersed within the host polymer is provided. The membrane and the polymeric additive undergo reversible transitions of their charge from positive to neutral to negative. The polymeric additive is an amphiphilic block copolymer comprising a hydrophobic block and a hydrophilic block comprising repeat units bearing positively ionizable weak base and negatively ionizable weak acid functional groups. A polymer blend, a kit, and a method for manufacturing the membrane relying on phase inversion via immersion precipitation are provided. Use of the membrane for filtering a feed is also provided. It advantageously uses membranes that have an isoelectric point that is about that of a contaminant and / or foulant to be removed, which involves tuning the isoelectric point of the membrane by adjusting the ratio of repeat units bearing positively ionizable weak base and negatively ionizable weak acid functional groups.

This invention discloses an asymmetric polyethersulfone filter membrane, its preparation method, and its applications. The invention controls the content of non-solvents in the casting solution to be greater than the content of solvents, and combines vapor-induced phase separation (VIPS), thermally induced phase separation (TIPS), and immersion precipitation-induced phase separation (LIPS) to induce differential phase separation between the upper and lower layers of the coating simultaneously, resulting in an asymmetric polyethersulfone filter membrane with a three-layer structure and an inverted V-shaped cross-section. This asymmetric polyethersulfone filter membrane exhibits high sterilization rate, high filtration flux, and high loading capacity.

This invention discloses a method for preparing a porous membrane for separating polycyclic aromatic hydrocarbons (PAHs) from wastewater, and the porous membrane itself. The preparation method includes: firstly, grafting 1-vinyl-3-butylimidazolium tetrafluoroborate onto polyvinylidene fluoride (PVDF) substrate by electron beam irradiation to obtain a graft copolymer; then, preparing a PVDF-g-IL porous membrane using an immersion precipitation phase inversion method; finally, replacing the tetrafluoroborate anions in the PVDF-g-IL porous membrane with sulfobutyl-β-cyclodextrin anions using anion exchange technology to obtain a PVDF-g-IL-SBE-β-CD porous membrane. This invention also provides the PVDF-g-IL porous membrane and the PVDF-g-IL-SBE-β-CD porous membrane prepared by the above method. The porous membrane prepared by this invention exhibits excellent separation and removal performance for PAHs in wastewater, and the preparation process is simple and low-cost, showing broad application prospects.

The invention discloses a preparation method of a highly-crosslinked compact and uniform reverse osmosis membrane, which comprises the following steps: step 1, preparing a modified base membrane: dissolving a polymer in a solvent, standing and defoaming, and preparing the modified base membrane by adopting an immersion precipitation phase conversion method; and 2, preparing the composite reverse osmosis membrane, wherein a step-by-step interfacial polymerization method is adopted to accurately control the reaction monomer in a spraying manner to prepare the composite membrane. The pits in the surface of the base membrane are filled and leveled up in advance through amino-containing micromolecules with extremely low concentration, the uniformity of the surface of the base membrane is improved, and then a polyamide network layer grows layer by layer through a step-by-step interfacial polymerization method to finally form a compact and complete desalination layer. In order to improve the cross-linking degree of a polyamide network, an inter-chain cross-linking agent is introduced at the same time in an interfacial polymerization reaction stage, so that the cross-linked aromatic polyamide is further cross-linked under the condition that the basic structure of the aromatic polyamide membrane is kept unchanged, and the purpose of improving the cross-linking degree is achieved.

This invention belongs to the field of photocatalysis and membrane separation technology, specifically relating to a highly efficient Cs3Bi2Br9 / Mn 0.3 Cd 0.7 S@P84 composite photocatalytic membrane, its preparation method, and its application. This invention prepares Cs3Bi2Br9 modified Mn nanoparticles via a hydrothermal method. 0.3 Cd 0.7 The catalyst obtained from S was then subjected to an immersion precipitation phase inversion method to transform Cs3Bi2Br9 / Mn. 0.3 Cd 0.7 The S-composite photocatalyst was immobilized on a P84 membrane. By combining photocatalysis with membrane separation, the removal rate of formaldehyde (0.2 mg / L) in the air reached 88% within 90 minutes, with good cycle performance and stability.