Water treatment composite membrane and method for preparing the same

Abstract

The application discloses a water treatment composite membrane and a preparation method thereof, and belongs to the field of membrane separation technology. The preparation method of the water treatment composite membrane comprises the following steps: dissolving an oil-soluble initiator, an oil-soluble monomer and an oil-soluble crosslinking agent in an organic solvent to prepare an oil phase, dissolving a water-soluble initiator, a water-soluble monomer and a water-soluble crosslinking agent in water to prepare a water phase; under the condition of 0-50 DEG C, immersing a polymer support layer in the water phase for 0.5-30 min, taking out the support layer, and then immersing the support layer in the oil phase for 0.5-30 min to obtain the water treatment composite membrane; the half-life period of the oil-soluble initiator and the water-soluble initiator under the condition of 0-50 DEG C is greater than 50 h, and the half-life period of the mixture of the oil-soluble initiator and the water-soluble initiator under the condition of 0-50 DEG C is less than 5 h. The water treatment composite membrane has a wide application range because the selective separation layer of the water treatment composite membrane is rich in a large number of functional functional groups, and the surface chemical properties and the charging properties are adjustable.

Description

Technical Field

[0001] This invention relates to the field of separation membrane materials technology, specifically to a water treatment composite membrane and its preparation method. Background Technology

[0002] With increasing environmental awareness, especially regarding water quality, membrane separation technology has gradually come into focus since the last century, being used in conventional water treatment processes such as seawater desalination, distillation, and adsorption. Although membrane separation technology consumes less energy than traditional separation technologies, how to efficiently utilize and conserve energy has become another major challenge facing this technology.

[0003] Common types of wastewater in daily life include starch wastewater, which has a high organic content and a COD concentration typically around 8000 mg / L; medical wastewater, mainly composed of bacteria and pathogens; dairy wastewater, with a high concentration of organic matter; papermaking wastewater, with a high content of organic pollutants, poor biodegradability, and high toxicity; dyeing and printing wastewater, with a high content of organic pollutants, high alkalinity, and significant water quality fluctuations; and textile wastewater, containing large amounts of toxic dyes and inorganic salts (such as Na₂SO₄ and NaCl), which is one of the most challenging industrial wastewaters. As can be seen from the above, all these impurities require nanofiltration to remove. Direct discharge of these pollutants not only severely pollutes the environment but also causes economic losses.

[0004] Nanofiltration (NF) is characterized by its environmental friendliness and cost-effectiveness; it typically exhibits high flux under low-pressure driving, and most importantly, high dye rejection and high salt permeability. However, current NF membranes' selective separation layers are prepared by interfacial polycondensation, making the control of the selective separation layer's surface chemical properties quite complex. Therefore, there is a need to find an efficient method for synthesizing selective separation layers with different functional groups. Summary of the Invention

[0005] To address at least one of the aforementioned problems, this invention provides a water treatment composite membrane and its preparation method.

[0006] The technical solution of this invention is: a method for preparing a water treatment composite membrane, comprising the following steps,

[0007] The oil-soluble initiator, oil-soluble monomer, and oil-soluble crosslinking agent are dissolved in an organic solvent and prepared as an oil phase; the water-soluble initiator, water-soluble monomer, and water-soluble crosslinking agent are dissolved in water and prepared as an aqueous phase.

[0008] Under conditions of 0–50°C, the polymer support layer is immersed in the aqueous phase for 0.5–30 min, the support layer is removed, and then immersed in the oil phase for 0.5–30 min to obtain the product.

[0009] The half-life of both the oil-soluble initiator and the water-soluble initiator is greater than 50 h under conditions of 0–50 °C. When the oil-soluble initiator and the water-soluble initiator are mixed, the half-life under conditions of 0–50 °C is less than 5 h.

[0010] In this invention, the main reaction process is as follows: Since the water-soluble and oil-soluble initiators have high half-lives when present alone, the aqueous and oil phases do not directly undergo polymerization. After the polymer support layer adsorbs a certain amount of water-soluble monomers, water-soluble initiators, and water-soluble crosslinking agents in the aqueous phase, it is then placed in the oil phase. At this point, the water-soluble initiators on the surface of the polymer support layer and the oil-soluble initiators at the interface mix. The water-soluble monomers and water-soluble crosslinking agents on the surface of the polymer support layer, as well as the oil-soluble monomers and oil-soluble crosslinking agents at the interface, begin a free radical polymerization reaction at the interface of the polymer support layer, thereby modifying the polymer support layer. While existing technologies also employ free radical polymers to prepare membrane materials, these typically involve spraying a raw material solution (monomer, initiator, crosslinking agent, and solvent) onto the surface of a support layer under conditions conducive to free radical polymerization. The drawback of this technique is that, because the raw material solution is directly sprayed onto the support surface, the final film thickness is usually large and difficult to control, resulting in relatively poor performance. Furthermore, the polymer generated using this method is deposited on the support layer, which has the disadvantage of weak interaction between polymer microparticles and between the polymer and the support layer, leading to lower film strength. Those skilled in the art will recognize that, because this invention utilizes interfacial polymerization, the film thickness is uniform, and the film thickness can be controlled by adjusting the reaction time. Simultaneously, interfacial polymerization allows polymer microparticles to overlap and even crosslink, forming strong interaction forces. The polymer film also has a large contact area with the support layer surface, resulting in strong interaction forces and relatively high film strength.

[0011] One embodiment of the present invention is that the oil-soluble initiator is at least one of cumene hydroperoxide, tert-butyl hydroperoxide, dicumyl peroxide, di-tert-butyl peroxide, benzoyl peroxide, dodecyl peroxide, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyvalerate, diisopropyl peroxide, dicyclohexyl peroxide, tetramethylethylenediamine, N,N-dimethyldodecylamine, N,N-dimethyloctylamine, N,N-dimethyltetradecylamine, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethylbenzylamine, triethylaluminum, and triethylboron; and the oil-soluble crosslinking agent is ethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, ethylene glycol diacrylate, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, etc. The oil-soluble initiator is selected from acrylate, pentaerythritol tetraacrylate, triallylamine, and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and the mass ratio of the oil-soluble initiator, the oil-soluble crosslinking agent, and the oil-soluble monomer is 0.05–5:0.5–30:100; the water-soluble initiator is selected from at least one of azobisisobutyramidine hydrochloride, azobisisobutyramidazolin hydrochloride, ammonium persulfate, potassium persulfate, hydrogen peroxide, sodium bisulfite, and sodium metabisulfite, and the water-soluble crosslinking agent is selected from at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol dimethacrylate, and the mass ratio of the water-soluble initiator, the water-soluble crosslinking agent, and water is 0.05–5:0.5–30:100.

[0012] In one embodiment of the present invention, when the oil-soluble initiator is a peroxide, the water-soluble initiator is one of azobisisobutyramidine hydrochloride, azobisisobutyramimidazole hydrochloride, ammonium persulfate, potassium persulfate, tetramethylethylenediamine, tetraethylethylenediamine, sodium bisulfite, and sodium metabisulfite; when the oil-soluble initiator is an amine or triethyl initiator, the water-soluble initiator is one of hydrogen peroxide, ammonium persulfate, potassium persulfate, and cumene hydroperoxide.

[0013] One embodiment of the present invention is that the oil-soluble monomer is at least one selected from isobutylene, styrene, vinyl chloride, vinylidene fluoride, vinyl fluoride, tetrafluoroethylene, trifluorochloroethylene, acrylonitrile, vinyl acetate, vinyl alcohol, vinyl alkyl ether, butadiene, isoprene, and chloroprene, and the mass ratio of the oil-soluble monomer to the organic solvent is 0 to 400:100.

[0014] Furthermore, when containing two or more oil-soluble monomers, the molar ratio of any two oil-soluble monomers is 1:0.1 to 10.

[0015] One embodiment of the present invention is that the organic solvent is one of cyclohexane, ethyl acetate, styrene, butyl acetate, chloromethane, dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, and xylene, and the mass ratio of the organic solvent to the oil-soluble monomer is 0-4:1.

[0016] One embodiment of the present invention is that the water-soluble monomer is one of succinic acid, acrylic acid and its salts, methacrylic acid and its salts, p-styrenesulfonic acid and its salts, acrylamide, and vinylpyrrolidone; the mass ratio of the aqueous monomer to water is 0.5 to 30:100.

[0017] Furthermore, when containing two or more water-soluble monomers, the molar ratio of any two water-soluble monomers is 1:0.1 to 10.

[0018] One embodiment of the present invention is that the polymer support layer is one of polysulfone, polyethersulfone, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyaryletheronitrile, polyethersulfone ketone, polyacrylonitrile, cellulose, and cellulose acetate, and its surface pore size is 10-100 nm.

[0019] Another objective of this invention is to provide a water treatment composite membrane prepared using any of the methods described above. This water treatment membrane exhibits excellent separation capabilities, and, moreover, allows for the selection of suitable monomers for interfacial polymerization based on specific circumstances, significantly broadening its application range.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The water treatment composite membrane involved in this invention has a selective separation layer rich in a large number of functional groups, such as hydroxyl, carboxyl, ester, ether, ketone, aldehyde, amino, nitro, mercapto, sulfonic acid, etc., and its surface chemical properties and charge properties are adjustable.

[0022] (2) The water treatment composite membrane involved in this invention has a selective separation layer prepared by interfacial free radical polymerization with high separation performance.

[0023] (3) The raw materials for the preparation process of the present invention are readily available, the operation is simple, and all solvents can be recycled and reused, which is environmentally friendly.

[0024] (4) The water treatment composite membrane involved in this invention can be applied to nanofiltration, reverse osmosis, forward osmosis and other fields. It has the advantages of high separation performance, easy cleaning and long service life.

[0025] (5) The water treatment composite membrane preparation process involved in this invention is flexible and versatile. Through interfacial free radical polymerization, the preparation conditions can be improved according to the needs, thereby adapting to different actual industrial production conditions, which is conducive to industrial production. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0027] Unless otherwise specified, the operating methods used in the following embodiments are all common methods in the art.

[0028] Unless otherwise specified, the raw materials used in the following embodiments are all conventional commercial products.

[0029] In the following embodiments, the support layer used is a conventional support layer specification in the art, with a pore size between 10 and 100 nm.

[0030] In the following embodiments, the half-life of the initiation system refers to the half-life under the reaction temperature conditions.

[0031] Example 1

[0032] 100g of styrene, 24.9g of ethylene glycol dimethacrylate, and 0.5g of cumene hydrogen peroxide were dissolved in 87g of isopropanol to obtain the oil phase; 23.7g of sodium p-styrene sulfonate, 2.7g of potassium persulfate, and 1.3g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 0.83h.

[0033] At 41°C, the polysulfone support layer is immersed in the aqueous phase for 3 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 14 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0034] Using an aqueous solution of 50 ppm Eriochrome Black T and 1000 ppm sodium sulfate as the feed solution, the transmembrane pressure difference was 3 bar. At room temperature, the water flux of the composite membrane for water treatment was 25.6 LMH / bar, with an Eriochrome Black T rejection rate of 96.7% and a sodium sulfate rejection rate of 92.3%.

[0035] Example 2

[0036] 100g of acrylonitrile, 8.2g of butanediol dimethacrylate, and 1.1g of tert-butyl hydroperoxide were dissolved in 313g of white oil to obtain the oil phase; 30.7g of sodium styrene sulfonate, 1.5g of sodium azobisisobutyramidine hydrochloride, and 0.9g of N,N-dimethylacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.37h.

[0037] At 15°C, the polyvinylidene fluoride support layer is immersed in the aqueous phase for 4 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 18 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0038] Using an aqueous solution of 50 ppm Congo red and 1000 ppm magnesium sulfate as the feed solution, the transmembrane pressure difference was 2 bar. At room temperature, the water flux of the water treatment composite membrane was 25.1 LMH / bar, with a Congo red rejection rate of 98.1% and a magnesium sulfate rejection rate of 89.3%.

[0039] Example 3

[0040] 100g of isobutylene, 18.5g of hexanediol dimethacrylate, and 1.9g of dicumyl peroxide were dissolved in 243g of n-butanol to obtain the oil phase; 27.2g of N,N-methylenebisacrylamide and 3.6g of ammonium persulfate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.05h.

[0041] At 20°C, the polyethersulfone ethylene support layer is immersed in the aqueous phase for 9 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed. Then, it is immersed in the oil phase for 20 minutes, and the residual oil phase on its surface is removed to obtain the final product.

[0042] Using an aqueous solution of 50 ppm methylene blue and 1000 ppm sodium sulfate as the feed solution, the transmembrane pressure difference was 4 bar. At room temperature, the water flux of the water treatment composite membrane was 31.3 LMH / bar, with a Congo red rejection rate of 97.4% and a sodium sulfate rejection rate of 93.7%.

[0043] Example 4

[0044] 100g of styrene, 10.8g of trimethylolpropane trimethacrylate, and 4.2g of di-tert-butyl peroxide were dissolved in 226g of diesel oil to obtain the oil phase; 15.9g of methacrylic acid, 2.1g of potassium persulfate, and 1.4g of polyethylene glycol diacrylate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.27h.

[0045] At 33°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 5 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 23 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0046] Using an aqueous solution of 1000 ppm sodium sulfate and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 3 bar. At room temperature, the water flux of the composite membrane was 24.6 LMH / bar, with a sodium chloride rejection rate of 6.3% and a sodium sulfate rejection rate of 94.1%.

[0047] Example 5

[0048] 100g of vinyl chloride, 22.3g of ethylene glycol diacrylate, and 4.0g of benzoyl peroxide were dissolved in 70g of diethyl ether to obtain the oil phase; 34.1g of p-styrene sulfonic acid, 2.3g of sodium bisulfite, and 0.1g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.66h.

[0049] At 9°C, the polyether sulfone ketone support layer is immersed in the aqueous phase for 3 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 16 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0050] Using an aqueous solution of 50 ppm Congo red and 50 ppm methylene blue as the feed solution, the transmembrane pressure difference was 6 bar. At room temperature, the water flux of the water treatment composite membrane was 23.0 LMH / bar, with a Congo red rejection rate of 98.7% and a methylene blue rejection rate of 99.1%.

[0051] Example 6

[0052] 100g of polyvinylidene fluoride and styrene (mass ratio 1:2), 6.9g of methyl methacrylate, and 1.5g of dodecyl peroxide were dissolved in 296g of carbon tetrachloride to obtain the oil phase; 24.6g of vinylpyrrolidone, 5.0g of sodium metabisulfite, and 2.9g of acrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.15h.

[0053] At 35°C, the polyether sulfone ketone support layer is immersed in the aqueous phase for 6 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 29 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0054] Using an aqueous solution of 1000 ppm humic acid and 1000 ppm N,N-methylenebisacrylamide sodium chloride as the feed solution, the transmembrane pressure difference was 2 bar. At room temperature, the water flux of the composite membrane was 27.7 LMH / bar, with a humic acid rejection rate of 97.3% and a sodium sulfate rejection rate of 94.5%.

[0055] Example 7

[0056] 100g of tetrafluoroethylene, 19.7g of hexanediol dimethacrylate, and 1.7g of tert-butyl peroxide were dissolved in 261g of n-hexane to obtain the oil phase; 19.3g of sodium methacrylate, 1.7g of potassium persulfate, and 1.8g of N,N-dimethylacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.80h.

[0057] At 2°C, the polyacrylonitrile support layer is immersed in the aqueous phase for 5 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 10 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0058] Using an aqueous solution of 50 ppm Chrome Black T and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 4 bar. At room temperature, the water flux of the composite membrane was 31.9 LMH / bar, the Chrome Black T rejection rate was 95.9%, and the sodium chloride rejection rate was 20.0%.

[0059] Example 8

[0060] 100g of trifluorochloroethylene, 27.4g of trimethylolpropane trimethacrylate, and 1.7g of tert-butyl peroxide were dissolved in 104g of isooctane to obtain the oil phase; 19.3g of sodium methacrylate, 1.7g of potassium peroxide, and 1.8g of N,N-dimethylacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.62h.

[0061] At 10°C, the polyvinyl chloride support layer is immersed in the aqueous phase for 8 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed. Then, it is immersed in the oil phase for 22 minutes, and the residual oil phase on its surface is removed to obtain the final product.

[0062] Using an aqueous solution of 1000 ppm sodium sulfate and 1000 ppm magnesium sulfate as the feed solution, the transmembrane pressure difference was 4 bar. At room temperature, the water flux of the composite membrane for water treatment was 30.3 LMH / bar, with a magnesium sulfate rejection rate of 97.6% and a sodium sulfate rejection rate of 98.1%.

[0063] Example 9

[0064] 100g of acrylonitrile, 1.8g of ethylene glycol diacrylate, and 2.5g of cumene hydroperoxide were dissolved in a mixed solution of 37g of benzene and 15g of toluene to obtain the oil phase; 125.4g of sodium styrene sulfonate, 0.7g of sodium azobisisobutyramidine hydrochloride, and 2.5g of ethylene glycol diacrylate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 0.92h.

[0065] At 37°C, the cellulose support layer is immersed in the aqueous phase for 9 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 8 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0066] Using an aqueous solution of 50 ppm methylene blue and 50 ppm Congo red as the feed solution, the transmembrane pressure difference was 3 bar. At room temperature, the water flux of the water treatment composite membrane was 33.4 LMH / bar, with a methylene blue rejection rate of 99.5% and a Congo red rejection rate of 97.1%.

[0067] Example 10

[0068] 100g of styrene, 3.1g of methyl methacrylate, and 4.8g of N,N-dimethyloctylamine were dissolved in 348g of toluene to obtain the oil phase; 22.0g of vinylpyrrolidone, 4.8g of ammonium persulfate, and 0.3g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 0.5h.

[0069] At 50°C, the polytetrafluoroethylene support layer is immersed in the aqueous phase for 1 minute and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 30 minutes, and then removed and the residual oil phase on its surface is removed to obtain the final product.

[0070] Using an aqueous solution of 1000 ppm magnesium sulfate and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 5 bar. At room temperature, the water flux of the composite membrane was 30.8 LMH / bar, with a sodium chloride rejection rate of 9.6% and a magnesium sulfate rejection rate of 96.7%.

[0071] Example 11

[0072] 100g of ethyl acetate, 12.0g of ethylene glycol dimethacrylate, and 3.8g of N,N-dimethyltetradecylamine were dissolved in dimethyl carbonate to obtain the oil phase; 35.0g of sodium methacrylate and 1.9g of potassium persulfate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.5h.

[0073] At 30°C, the cellulose acetate support layer is immersed in the aqueous phase for 8 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed. Then, it is immersed in the oil phase for 27 minutes, and the residual oil phase on its surface is removed to obtain the final product.

[0074] Using an aqueous solution of 100 ppm Congo red and 2000 ppm sodium sulfate as the feed solution, the transmembrane pressure difference was 1 bar. At room temperature, the water flux of the composite membrane was 34.0 LMH / bar, with a Congo red rejection rate of 98.3% and a sodium sulfate rejection rate of 88.4%.

[0075] Example 12

[0076] 100g of isoprene, 28.7g of butanediol dimethacrylate, and 2.8g of cumene hydrogen peroxide were dissolved in a mixed solvent of 75g of ethyl acetate and 64g of isopropanol to obtain the oil phase; 32.4g of p-styrene sulfonic acid, 4.8g of sodium bisulfite, and 2.2g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.13h.

[0077] At 18°C, the polysulfone support layer is immersed in the aqueous phase for 4 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 11 minutes, and then removed and the residual oil phase on its surface is removed to obtain the final product.

[0078] Using an aqueous solution of 1000 ppm humic acid and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 1 bar. At room temperature, the water flux of the water treatment composite membrane was 32.9 LMH / bar, the humic acid rejection rate was 98.8%, and the sodium chloride rejection rate was 18.7%.

[0079] Example 13

[0080] 100g of chloroprene, 17.2g of methyl methacrylate, and 4.6g of benzoyl peroxide were dissolved in 122g of chloroform to obtain the oil phase; 6.7g of sodium styrene sulfonate, 3.4g of sodium metabisulfite, and 1.0g of polyethylene glycol diacrylate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.97h.

[0081] At 21°C, the polysulfone support layer is immersed in the aqueous phase for 7 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 13 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0082] An aqueous solution of 100 ppm methylene blue and 1000 ppm magnesium chloride was used as the feed solution, with a transmembrane pressure difference of 6 bar. At room temperature, the water flux of the composite membrane was 36.1 LMH / bar, with a methylene blue rejection rate of 95.3% and a magnesium chloride rejection rate of 7.6%.

[0083] Example 14

[0084] 100g of trifluorochloroethylene, 21.0g of hexanediol dimethacrylate, and 3.0g of triethylboron were dissolved in 365g of isobutanol to obtain the oil phase; 20.2g of methacrylic acid, 2.8g of potassium persulfate, and 0.5g of polyethylene glycol dimethacrylate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 0.87h.

[0085] At 39°C, the polyacrylonitrile support layer is immersed in the aqueous phase for 10 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 26 minutes, and then removed and the residual oil phase on its surface is removed to obtain the final product.

[0086] Using an aqueous solution of 1000 ppm Congo red and 1000 ppm sodium sulfate as the feed solution, the transmembrane pressure difference was 3 bar. At room temperature, the water flux of the composite membrane for water treatment was 28.7 LMH / bar, with a Congo red rejection rate of 96.0% and a sodium sulfate rejection rate of 98.0%.

[0087] Example 15

[0088] 100g of acrylonitrile, 5.6g of trimethylolpropane trimethacrylate, and 2.7g of tetramethylethylenediamine were dissolved in 35g of cyclohexane to obtain the oil phase; 22.8g of p-styrenesulfonic acid, 3.2g of sodium bisulfite, and 2.3g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 0.65h.

[0089] At 46°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 3 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 19 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0090] Using an aqueous solution of 1000 ppm sodium sulfate and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 2 bar. At room temperature, the water flux of the composite membrane was 34.5 LMH / bar, with a sodium sulfate rejection rate of 96.3% and a sodium chloride rejection rate of 18.5%.

[0091] Example 16

[0092] 100g of acrylonitrile and isobutylene, wherein the mass ratio of ethylene to acrylonitrile is 1:1, 23.6g of ethylene glycol diacrylate, and 3.4g of cumene hydrogen peroxide were dissolved in 330g of dichloroethane to obtain the oil phase; 33.3g of sodium styrene sulfonate, 4.6g of potassium persulfate, and 1.6g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 2.51h.

[0093] At 11°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 8 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 19 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0094] Using an aqueous solution of 50 ppm Eriochrome Black T and 1000 ppm magnesium sulfate as the feed solution, the transmembrane pressure difference was 4 bar. At room temperature, the water flux of the composite membrane for water treatment was 24.0 LMH / bar, with an Eriochrome Black T rejection rate of 98.0% and a magnesium sulfate rejection rate of 93.2%.

[0095] Example 17

[0096] 100g of acrylonitrile, 15.9g of methyl methacrylate, and 2.3g of cumene hydrogen peroxide were dissolved in 278g of nitrobenzene to obtain the oil phase; 18.5g of acrylamide and 0.5g of potassium persulfate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.93h.

[0097] At 22°C, the polyethersulfone support layer is immersed in the aqueous phase for 3 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 24 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0098] Using an aqueous solution of 1000 ppm sodium sulfate and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 1 bar. At room temperature, the water flux of the composite membrane for water treatment was 27.2 LMH / bar, with a sodium sulfate rejection rate of 88.0% and a sodium chloride rejection rate of 17.4%.

[0099] Example 18

[0100] 100g of isobutylene, 0.5g of ethylene glycol dimethacrylate, and 0.9g of di-tert-butyl peroxide were dissolved in 174g of ethylbenzene to obtain the oil phase; 28.9g of acrylamide, 0.9g of sodium metabisulfite, and 1.7g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.71h.

[0101] At 26°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 6 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 25 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0102] An aqueous solution of 100 ppm methylene blue and 100 ppm Congo red was used as the feed solution, with a transmembrane pressure difference of 3 bar. At room temperature, the water flux of the water treatment composite membrane was 26.7 LMH / bar, with a methylene blue rejection rate of 98.6% and a Congo red rejection rate of 97.4%.

[0103] Example 19

[0104] 100g of acrylonitrile, 14.6g of trimethylolpropane trimethacrylate, and 3.6g of benzoyl peroxide were dissolved in 17g of xylene to obtain the oil phase; 28.9g of methacrylic acid and 4.2g of sodium metabisulfite were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.62h.

[0105] At 28°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 2 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 15 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0106] Using an aqueous solution of 1000 ppm sodium sulfate and 1000 ppm magnesium sulfate as the feed solution, the transmembrane pressure difference was 5 bar. At room temperature, the water flux of the composite membrane for water treatment was 29.8 LMH / bar, with a sodium sulfate rejection rate of 97.6% and a magnesium sulfate rejection rate of 97.4%.

[0107] Example 20

[0108] An oil phase was obtained by dissolving 100g of styrene, 4.3g of ethylene glycol diacrylate, 3.2g of dodecyl peroxide, and 5.9g of methyl isobutyl ketone; an aqueous phase was obtained by dissolving 26.3g of vinylpyrrolidone and 3.0g of sodium bisulfite in 100g of water. The half-life of this initiation system was 2.42h.

[0109] At 13°C, the polyacrylonitrile support layer is immersed in the aqueous phase for 2 minutes and then removed to remove the residual aqueous phase on the surface of the support layer. Then it is immersed in the oil phase for 15 minutes, removed, and the residual oil phase on its surface is removed to obtain the final product.

[0110] An aqueous solution of 1000 ppm humic acid and 1000 ppm sodium chloride was used as the feed solution, with a transmembrane pressure difference of 4 bar. At room temperature, the water flux of the composite membrane for water treatment was 28.2 LMH / bar, with a humic acid rejection rate of 99.6% and a sodium chloride rejection rate of 10.2%.

[0111] Example 21

[0112] 100g of vinyl chloride, 26.2g of methyl methacrylate, and 4.4g of butyl tert-valerate peroxide were dissolved in 157g of anisole to obtain the oil phase; 31.5g of sodium methacrylate, 2.1g of potassium persulfate, and 3.8g of ammonium persulfate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 3.0h.

[0113] At 0°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 10 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 3 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0114] An aqueous solution of 1000 ppm humic acid and 1000 ppm methylene blue was used as the feed solution, with a transmembrane pressure difference of 2 bar. At room temperature, the water flux of the composite membrane for water treatment was 35.0 LMH / bar, with a humic acid rejection rate of 98.6% and a methylene blue rejection rate of 97.8%.

[0115] Example 22

[0116] 100g of vinylidene fluoride, 13.3g of ethylene glycol dimethacrylate, and 0.7g of di-tert-butyl peroxide were dissolved in 191g of trichloroethylene to obtain the oil phase; 15.0g of methacrylic acid, 3.8g of sodium azobisisobutyramidine hydrochloride, and 3.0g of N,N-methylenebisacrylamide were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.57h.

[0117] At 29°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 10 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 10 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0118] An aqueous solution of 1000 ppm magnesium sulfate and 1000 ppm magnesium chloride was used as the feed solution, with a transmembrane pressure difference of 3 bar. At room temperature, the water flux of the composite membrane was 23.5 LMH / bar, with a magnesium sulfate rejection rate of 88.9% and a magnesium chloride rejection rate of 5.7%.

[0119] Example 23

[0120] An oil phase was obtained by dissolving 100g of tetrafluoroethylene, 9.5g of trimethylolpropane trimethacrylate, and 2.1g of diisopropyl peroxide dicarbonate; an aqueous phase was obtained by dissolving 29.8g of acrylamide and 1.3g of sodium metabisulfite in 100g of water. The half-life of this initiation system was 1.82h.

[0121] At 24°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 10 minutes and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 9 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0122] Using an aqueous solution of 50 ppm Chrome Black T and 1000 ppm sodium chloride as the feed solution, the transmembrane pressure difference was 1 bar. At room temperature, the water flux of the water treatment composite membrane was 32.4 LMH / bar, the Chrome Black T rejection rate was 96.4%, and the sodium chloride rejection rate was 8.9%.

[0123] Example 24

[0124] 100g of acrylonitrile, 30g of butanediol dimethacrylate, and 5.0g of cumene hydrogen peroxide were dissolved in a mixed solvent of 220g of n-heptane and 180g of isopropanol to obtain the oil phase; 17.6g of sodium styrene sulfonate, 1.1g of potassium persulfate, and 2.6g of polyethylene glycol dimethacrylate were dissolved in 100g of water to obtain the aqueous phase. The half-life of this initiation system is 1.27h.

[0125] At 33°C, the polyarylene ether nitrile support layer is immersed in the aqueous phase for 1 minute and then removed. The residual aqueous phase on the surface of the support layer is removed, and then it is immersed in the oil phase for 17 minutes. The residual oil phase on its surface is then removed to obtain the final product.

[0126] Using an aqueous solution of 50 ppm Congo red and 50 ppm methylene blue as the feed solution, the transmembrane pressure difference was 3 bar. At room temperature, the water flux of the water treatment composite membrane was 29.3 LMH / bar, with a Congo red rejection rate of 98.5% and a methylene blue rejection rate of 99.1%.

[0127] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the embodiments of the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a water treatment composite membrane, characterized in that, Includes the following steps, The oil-soluble initiator, oil-soluble monomer, and oil-soluble crosslinking agent are dissolved in an organic solvent and prepared as an oil phase; the water-soluble initiator, water-soluble monomer, and water-soluble crosslinking agent are dissolved in water and prepared as an aqueous phase. Under conditions of 0~50℃, the polymer support layer is immersed in the aqueous phase for 0.5~30 min, the support layer is removed, and then immersed in the oil phase for 0.5~30 min to obtain the product. The half-life of both the oil-soluble initiator and the water-soluble initiator is greater than 50 h under conditions of 0~50℃, and the half-life of the mixture of the oil-soluble initiator and the water-soluble initiator is less than 5 h under conditions of 0~50℃. The oil-soluble initiator is at least one of cumene hydroperoxide, tert-butyl hydroperoxide, dicumene peroxide, di-tert-butyl peroxide, benzoyl peroxide, dodecyl peroxide, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxyvalerate, diisopropyl peroxide, dicyclohexyl peroxide, tetramethylethylenediamine, N,N-dimethyldodecylamine, N,N-dimethyloctylamine, N,N-dimethyltetradecylamine, N,N-dimethylaniline, N,N-diethylaniline, N,N-dimethylbenzylamine, triethylaluminum, and triethylboron; the water-soluble initiator is at least one of azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, ammonium persulfate, potassium persulfate, tetramethylethylenediamine, sodium bisulfite, and sodium metabisulfite. When the oil-soluble initiator is a peroxide, the water-soluble initiator is one of azobisisobutyramidine hydrochloride, azobisisobutyramimidazole hydrochloride, ammonium persulfate, potassium persulfate, tetramethylethylenediamine, sodium bisulfite, and sodium metabisulfite; when the oil-soluble initiator is an amine or triethyl initiator, the water-soluble initiator is one of ammonium persulfate and potassium persulfate. The oil-soluble monomer is at least one of isobutylene, styrene, vinyl chloride, vinylidene fluoride, vinyl fluoride, tetrafluoroethylene, trifluorochloroethylene, acrylonitrile, vinyl acetate, vinyl alkyl ether, butadiene, isoprene, and chloroprene, and the mass ratio of the oil-soluble monomer to the organic solvent is 0~400:

100. The water-soluble monomer is one of acrylic acid and its salts, methacrylic acid and its salts, p-styrene sulfonic acid and its salts, acrylamide, and vinylpyrrolidone; the mass ratio of the water-soluble monomer to water is 0.5~30:

100. The mass ratio of the oil-soluble initiator, the oil-soluble crosslinking agent, and the oil-soluble monomer is 0.05~5:0.5~30:100, and the mass ratio of the water-soluble initiator, the water-soluble crosslinking agent, and water is 0.05~5:0.5~30:

100.

2. The method according to claim 1, characterized in that, The oil-soluble crosslinking agent is one of ethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol dimethacrylate, ethylene glycol diacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, triallylamine, and 1,3,5-triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; the water-soluble crosslinking agent is at least one of N,N-methylenebisacrylamide, polyethylene glycol diacrylate, and polyethylene glycol dimethacrylate.

3. The method according to claim 1, characterized in that, The organic solvent is one of cyclohexane, ethyl acetate, styrene, butyl acetate, chloromethane, dichloromethane, chloroform, carbon tetrachloride, benzene, toluene, and xylene, and the mass ratio of the organic solvent to the oil-soluble monomer is 0-4:

1.

4. The method according to claim 1, characterized in that, The polymer support layer is one of polysulfone, polyethersulfone, polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride, polyaryletheronitrile, polyethersulfone ketone, polyacrylonitrile, cellulose, and cellulose acetate, and its surface pore size is 10-100 nm.

5. A water treatment composite membrane, characterized in that, It is prepared by the method described in any one of claims 1 to 4.