A high-flux, high-salt rejection reverse osmosis membrane and its preparation method and application

Abstract

The present invention relates to the field of membrane separation technology, and specifically to a high-flux, high-salt rejection reverse osmosis membrane, and a preparation method and application thereof. The present invention sequentially contacts a porous base membrane with an aqueous solution and an oily solution to generate an interfacial polymerization reaction to form a nascent reverse osmosis membrane, and sequentially contacts the nascent reverse osmosis membrane with a nitrous acid or its salt solution and a hydrogen sulfite solution to obtain the high-flux, high-salt rejection reverse osmosis membrane; the aqueous solution contains an aqueous co-solvent, and the oily solution contains an oily co-solvent. The present invention innovatively adds a co-solvent to both the aqueous solution and the oily solution during the interfacial polymerization reaction to regulate the microstructure of the polyamide layer, and the diazo reaction promotes further cross-linking of the residual aniline groups, thereby achieving in-situ densification regulation of the polyamide network structure, successfully breaking through the trade-off effect of water flux and salt rejection of traditional reverse osmosis membranes.

Description

Technical Field

[0001] The present invention relates to the field of membrane separation technology, and in particular to a high-flux and high-salt rejection reverse osmosis membrane, a preparation method thereof, and applications thereof. Background Art

[0002] Reverse osmosis membranes are widely used in water treatment and seawater desalination. However, they currently suffer from high energy consumption and low water flux, limiting their continued application. However, increasing the water flux of reverse osmosis membranes often results in a decrease in their salt retention rate. Therefore, how to further increase the water flux of reverse osmosis membranes while maintaining high salt retention has been a research hotspot in membrane separation technology.

[0003] The classical structure of reverse osmosis membrane is a composite structure, which is composed of a bottom non-woven fabric, an intermediate porous basement membrane and an upper separation layer. The polyamide upper separation layer is prepared by interfacial polymerization of oil phase monomer polyacyl chloride and water phase monomer polyamine. Prior art such as CN114950165A, CN111569675A, CN105169971A, adds a cosolvent in oil phase or aqueous phase to increase the miscibility of oil phase and aqueous phase, promotes the diffusion of polyamine monomers into the oil phase, forms a "large blade" structure, and thus significantly improves the flux of reverse osmosis membrane. However, adding a cosolvent alone in aqueous phase or oil phase will cause a bottleneck in flux increase. To ensure the maximization of membrane flux, the inventors have attempted to add a cosolvent in both aqueous solution and oil phase solution. In particular, when the cosolvent addition in the aqueous solution is greater than 1%, it was found that it causes the polyamide network to become loose, and causes the reverse osmosis membrane salt retention rate to decrease.

[0004] After the polyamide membrane is post-treated with diazotization, the diazotizing agent reacts with aniline to form an intermediate product, diazonium salt. The diazonium salt further undergoes a coupling reaction with the benzene ring to produce an azo structure, which increases the cross-linking degree and density of the polymer network, thereby improving the salt retention rate. However, this is also accompanied by a decrease in water flux.

[0005] Based on the above background, in order to further improve the water flux of the reverse osmosis membrane while ensuring a high salt rejection rate, it is necessary to improve the existing preparation method of the reverse osmosis membrane. Summary of the Invention

[0006] The first object of the present invention is to provide a method for preparing a high-flux, high-salt rejection reverse osmosis membrane, which is simple and low in cost.

[0007] The second object of the present invention is to provide a high-flux, high-salt rejection reverse osmosis membrane with high water flux and high salt rejection.

[0008] The third purpose of the present invention is to provide an application of a high-flux, high-salt rejection reverse osmosis membrane, which has broad application prospects.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is:

[0010] A method for preparing a high-flux, high-salt rejection reverse osmosis membrane comprises: contacting a porous base membrane with an aqueous solution and an oily solution in sequence to generate an interfacial polymerization reaction to form a nascent reverse osmosis membrane; and contacting the nascent reverse osmosis membrane with a nitrous acid solution or a salt thereof and a hydrogen sulfite solution in sequence to obtain the high-flux, high-salt rejection reverse osmosis membrane; the aqueous solution contains an aqueous co-solvent, the concentration of the aqueous co-solvent in the aqueous solution being 1-95wt%; and the oily solution contains an oily co-solvent.

[0011] Furthermore, the aqueous phase solution includes polyamine monomers, aqueous phase co-solvents and water, and the oil phase solution includes polyacyl chloride monomers, oil phase co-solvents and alkane solvents.

[0012] Furthermore, the aqueous co-solvent is one or more of an alcohol solvent, a ketone solvent, and an ether solvent that are miscible with water but do not react with amino groups; the oil-phase co-solvent is one or more of an ester solvent, a ketone solvent, and an ether solvent that are miscible with an alkane solvent but do not react with acyl chlorides; and the concentration of the oil-phase co-solvent in the oil-phase solution is 0.01-20 wt%.

[0013] Furthermore, the aqueous phase co-solvent is selected from one or more of ethanol, n-propanol, isopropanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, acetone, methyl ethyl ketone, ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol ethyl ether acetate; the oil phase co-solvent is selected from one or more of ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, butyric acid, One or more of methyl ester, ethyl butyrate, propyl butyrate, butyl butyrate, dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, diethyl succinate, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, diethylene glycol ethyl ether acetate, diethylene glycol ethyl ether butyrate, diethylene glycol diacetate, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, and tetraethylene glycol dimethyl ether.

[0014] Furthermore, the concentration of nitrite in the nitrous acid or its salt solution is 0.005-5wt%, the solution temperature is 4-50°C, and the pH is 1-7; the time for the primary reverse osmosis membrane to contact the nitrous acid or its salt solution is 5-1800s; the concentration of the hydrosulfite solution is 0.05-5wt%, the temperature is 4-50°C, and the pH is 1-7; the time for the reverse osmosis membrane treated with the nitrous acid or its salt solution to contact the hydrosulfite solution is 5-1800s.

[0015] Furthermore, the contact time between the porous base membrane surface and the aqueous solution is 1-300 s; and the interfacial polymerization reaction time is 1-300 s.

[0016] Furthermore, the concentration of the polyamine monomer in the aqueous solution is 0.5-5wt%; the polyamine monomer is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, diaminotoluene, biphenylenediamine, and diaminonaphthalene; the concentration of the polyacyl chloride monomer in the oil phase solution is 0.01-5wt%; the polyacyl chloride monomer is selected from one or more of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, biphenyl trimesoyl chloride, biphenyl tetracarboxylic acid chloride, naphthalene dicarboxylic acid chloride, naphthalene tricarboxylic acid chloride, naphthalene tetracarboxylic acid chloride, malonyl chloride, succinyl chloride, glutaryl chloride, and adipoyl chloride; and the alkane solvent is selected from one or more of hexane, heptane, octane, nonane, decane, undecane, dodecane, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M.

[0017] Furthermore, the material of the porous base membrane is selected from one of polysulfone, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polyimide, polyetherimide, polyacrylonitrile, polyphenylene ether, polyphenylene sulfide, polyetherketone, and polyaryletherketone.

[0018] A high-flux and high-salt rejection reverse osmosis membrane is prepared by the above-mentioned preparation method.

[0019] The application of the above-mentioned high-flux and high-salt rejection reverse osmosis membrane in the field of water treatment.

[0020] The beneficial technical effects of the present invention are:

[0021] First, the present invention innovatively adds a co-solvent to both the aqueous solution and the oil phase solution during the interfacial polymerization reaction to regulate the microstructure of the polyamide layer. On the one hand, the water flux of the reverse osmosis membrane is significantly improved by forming a loose polymer network and a blade-like surface morphology. In response to the resulting problem of reduced salt retention rate, the present invention performs a diazotization post-treatment on the nascent reverse osmosis membrane. The diazotization reaction promotes further cross-linking of the residual aniline groups, thereby achieving in situ densification regulation of the polyamide network structure, successfully breaking through the trade-off effect between the water flux and salt retention rate of traditional reverse osmosis membranes.

[0022] Secondly, the present invention adds a co-solvent to the aqueous and oil phase solutions to promote the diffusion of amine monomers during interfacial polymerization. By selecting the aqueous and oil phase co-solvents, the amine content of the primary reverse osmosis membrane accounts for more than 20% of the total nitrogen content, thereby increasing the residual density of unreacted aniline functional groups on the surface of the primary polyamide membrane and providing sufficient reaction sites for subsequent functional modification.

[0023] Finally, the present invention creatively requires soaking in sodium bisulfite solution after soaking in sodium nitrite solution, thereby further improving the rejection rate of the reverse osmosis membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 are scanning electron microscope (SEM) images of the reverse osmosis membrane surfaces obtained in Examples 1-9, wherein a1-i1 are magnified at a factor of 10,000; a2-i2 are magnified at a factor of 50,000, wherein ai corresponds to the SEM images of the reverse osmosis membrane surfaces obtained in Examples 1-9, respectively;

[0025] Figure 2 These are scanning electron microscope (SEM) images of the reverse osmosis membrane surfaces obtained in Comparative Examples 1-5, wherein a1-e1 are magnified at a factor of 10,000; a2-e2 are magnified at a factor of 50,000, and ae correspond to the SEM images of the reverse osmosis membrane surfaces obtained in Comparative Examples 1-5, respectively. DETAILED DESCRIPTION

[0026] The following is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it is not intended that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art of the present invention, without departing from the inventive concept, several simple deductions or replacements can also be made, all of which should be considered to belong to the scope of protection of the present invention. The specific conditions not indicated in the examples are carried out according to conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0027] Example 1

[0028] Example 1 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0029] (1) Preparation of aqueous solution

[0030] Metaphenylenediamine, camphorsulfonic acid, triethylamine, and isopropyl alcohol were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % of metaphenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, and 50 wt % of isopropyl alcohol.

[0031] (2) Preparation of oil phase solution

[0032] Trimesoyl chloride and ethyl acetate were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.2 wt % of trimesoyl chloride and 5 wt % of ethyl acetate.

[0033] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 10 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 10 seconds, removing excess oil solution from the surface after the reaction is completed, heat-treating at 90°C for 360 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0034] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 0.3 wt%, a temperature of 25°C, and a pH of 3 for 60 s, and then soaked in a sodium bisulfite solution with a concentration of 1 wt%, a temperature of 25°C, and a pH of 3 for 60 s. After the soaking is completed, the high-flux and high-salt retention rate reverse osmosis membrane is obtained by rinsing.

[0035] Example 2

[0036] Example 2 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0037] (1) Preparation of aqueous solution

[0038] Diaminotoluene, camphorsulfonic acid, triethylamine and methyl ethyl ketone were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 5 wt % of diaminotoluene, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine and 1 wt % of methyl ethyl ketone.

[0039] (2) Preparation of oil phase solution

[0040] Biphenyl dicarboxylic acid chloride and dimethyl oxalate were added to nonane to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.5 wt % of biphenyl dicarboxylic acid chloride and 15 wt % of dimethyl oxalate.

[0041] (3) contacting the surface of the polyimide-based membrane with the aqueous solution prepared in step (1) for 8 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 15 seconds, removing excess oil solution from the surface after the reaction is completed, heat treating at 40°C for 600 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0042] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 0.1 wt%, a temperature of 4°C, and a pH of 1 for 5 s, and then soaked in a sodium bisulfite solution with a concentration of 1 wt%, a temperature of 4°C, and a pH of 1 for 5 s. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0043] Example 3

[0044] Example 3 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0045] (1) Preparation of aqueous solution

[0046] Diaminonaphthalene, camphorsulfonic acid, triethylamine and ethylene glycol monoethyl ether were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % of diaminonaphthalene, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine and 10 wt % of ethylene glycol monoethyl ether.

[0047] (2) Preparation of oil phase solution

[0048] Trimesoyl chloride and diethyl ether were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.2 wt % of trimesoyl chloride and 5 wt % of diethyl ether.

[0049] (3) contacting the surface of the polytetrafluoroethylene membrane with the aqueous solution prepared in step (1) for 30 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 30 seconds, removing excess oil solution from the surface after the reaction is completed, heat treating at 60°C for 500 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0050] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 0.5 wt%, a temperature of 15°C, and a pH of 3 for 30 seconds, and then soaked in a potassium bisulfite solution with a concentration of 0.5 wt%, a temperature of 15°C, and a pH of 3 for 1200 seconds. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0051] Example 4

[0052] Example 4 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0053] (1) Preparation of aqueous solution

[0054] Metaphenylenediamine, camphorsulfonic acid, triethylamine, and ethylene glycol monoethyl ether were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 4 wt % of metaphenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, and 30 wt % of ethylene glycol monoethyl ether.

[0055] (2) Preparation of oil phase solution

[0056] Naphthalene tricarbonyl chloride and diethyl oxalate were added to Isopar L to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 1 wt % of naphthalene tricarbonyl chloride and 20 wt % of diethyl oxalate.

[0057] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 80 seconds, removing excess aqueous solution on the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization reaction for 80 seconds, removing excess oil solution on the surface after the reaction is completed, heat treating at 100°C for 300 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0058] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a potassium nitrite solution with a concentration of 0.7 wt%, a temperature of 40°C, and a pH of 6 for 120 s, and then soaked in a sodium bisulfite solution with a concentration of 0.7 wt%, a temperature of 40°C, and a pH of 6 for 120 s. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0059] Example 5

[0060] Example 5 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0061] (1) Preparation of aqueous solution

[0062] m-phenylenediamine, camphorsulfonic acid, triethylamine, diethylene glycol ethyl ether acetate, and isopropyl alcohol were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 5 wt % of m-phenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, 5 wt % of diethylene glycol ethyl ether acetate, and 30 wt % of isopropyl alcohol.

[0063] (2) Preparation of oil phase solution

[0064] Trimesoyl chloride and triethylene glycol dimethyl ether were added to nonane to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 1 wt % of trimesoyl chloride and 3 wt % of triethylene glycol dimethyl ether.

[0065] (3) contacting the surface of the polyphenylene ether-based membrane with the aqueous solution prepared in step (1) for 100 seconds, removing excess aqueous solution on the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization reaction for 100 seconds, removing excess oil solution on the surface after the reaction is completed, heat treating at 120° C. for 100 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0066] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 2 wt%, a temperature of 50°C, and a pH of 2 for 5 seconds, and then soaked in a sodium bisulfite solution with a concentration of 2 wt%, a temperature of 50°C, and a pH of 2 for 10 seconds. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0067] Example 6

[0068] Example 6 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0069] (1) Preparation of aqueous solution

[0070] Metaphenylenediamine, camphorsulfonic acid, triethylamine, isopropyl alcohol, and diethylene glycol monomethyl ether were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % of metaphenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, 35 wt % of isopropyl alcohol, and 30 wt % of diethylene glycol monomethyl ether.

[0071] (2) Preparation of oil phase solution

[0072] Trimesoyl chloride and ethyl acetate were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: trimesoyl chloride 0.5 wt %, ethyl acetate 2 wt %.

[0073] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 200 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 200 seconds, removing excess oil solution from the surface after the reaction is completed, heat-treating at 150°C for 6 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0074] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 4 wt%, a temperature of 30°C, and a pH of 4 for 10 seconds, and then soaked in a sodium bisulfite solution with a concentration of 4 wt%, a temperature of 30°C, and a pH of 4 for 30 seconds. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0075] Example 7

[0076] Example 7 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0077] (1) Preparation of aqueous solution

[0078] m-phenylenediamine, camphorsulfonic acid, triethylamine, and diethylene glycol were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % m-phenylenediamine, 3 wt % camphorsulfonic acid, 2 wt % triethylamine, and 30 wt % diethylene glycol.

[0079] (2) Preparation of oil phase solution

[0080] Trimesoyl chloride, ethyl acetate, and 2-pentanone were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.2 wt % of trimesoyl chloride, 2 wt % of ethyl acetate, and 2 wt % of 2-pentanone.

[0081] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 300 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 300 seconds, removing excess oil solution from the surface after the reaction is completed, heat treating at 90°C for 360 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0082] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 5 wt%, a temperature of 32°C, and a pH of 3 for 8 seconds, and then soaked in a sodium bisulfite solution with a concentration of 5 wt%, a temperature of 32°C, and a pH of 3 for 10 seconds. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0083] Example 8

[0084] Example 8 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0085] (1) Preparation of aqueous solution

[0086] Metaphenylenediamine, camphorsulfonic acid, triethylamine, and isopropyl alcohol were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % of metaphenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, and 60 wt % of isopropyl alcohol.

[0087] (2) Preparation of oil phase solution

[0088] Trimesoyl chloride, ethyl acetate, and diethylene glycol diethyl ether were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.2 wt % of trimesoyl chloride, 2 wt % of ethyl acetate, and 0.3 wt % of diethylene glycol diethyl ether.

[0089] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 300 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 300 seconds, removing excess oil solution from the surface after the reaction is completed, heat treating at 90°C for 360 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0090] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 0.5 wt%, a temperature of 25°C, and a pH of 3 for 60 s, and then soaked in a sodium bisulfite solution with a concentration of 2 wt%, a temperature of 25°C, and a pH of 3 for 60 s. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0091] Example 9

[0092] Example 9 provides a method for preparing a high-flux, high-salt rejection reverse osmosis membrane. The specific preparation process is as follows:

[0093] (1) Preparation of aqueous solution

[0094] m-phenylenediamine, camphorsulfonic acid, triethylamine, and acetone were added to water to prepare a uniform and transparent aqueous solution. The concentrations of the components in the aqueous solution were as follows: 3 wt % of m-phenylenediamine, 3 wt % of camphorsulfonic acid, 2 wt % of triethylamine, and 5 wt % of acetone.

[0095] (2) Preparation of oil phase solution

[0096] Trimesoyl chloride, ethyl acetate, and ethylene glycol diethyl ether were added to Isopar G to prepare a homogeneous and transparent oil phase solution. The concentrations of the components in the oil phase solution were as follows: 0.2 wt % of trimesoyl chloride, 2 wt % of ethyl acetate, and 1.5 wt % of ethylene glycol diethyl ether.

[0097] (3) contacting the surface of the polysulfone-based membrane with the aqueous solution prepared in step (1) for 300 seconds, removing excess aqueous solution from the surface, contacting the membrane layer formed by the aqueous solution with the oil solution prepared in step (2) to cause interfacial polymerization for 300 seconds, removing excess oil solution from the surface after the reaction is completed, heat treating at 90°C for 360 seconds, and rinsing to obtain a primary reverse osmosis membrane;

[0098] (4) The nascent reverse osmosis membrane of step (3) is first soaked in a sodium nitrite solution with a concentration of 0.5 wt%, a temperature of 20°C, and a pH of 3 for 30 seconds, and then soaked in a sodium bisulfite solution with a concentration of 1 wt%, a temperature of 25°C, and a pH of 3 for 60 seconds. After the soaking is completed, the high-flux and high-salt rejection reverse osmosis membrane is obtained by rinsing.

[0099] Comparative Example 1

[0100] The difference between Comparative Example 1 and Example 1 is:

[0101] Omit step (4), and the rest is the same as in Example 1.

[0102] Comparative Example 2

[0103] The difference between Comparative Example 2 and Example 1 is:

[0104] No isopropanol was added to the aqueous phase solution, and no ethyl acetate was added to the oil phase solution. The rest was the same as in Example 1.

[0105] Comparative Example 3

[0106] The difference between Comparative Example 3 and Example 1 is:

[0107] No isopropyl alcohol was added to the aqueous solution, and the rest was the same as in Example 1.

[0108] Comparative Example 4

[0109] The difference between Comparative Example 4 and Example 1 is:

[0110] No ethyl acetate was added to the oil phase solution, and the rest was the same as in Example 1.

[0111] Comparative Example 5

[0112] The difference between Comparative Example 5 and Example 1 is:

[0113] In step (4), the sodium bisulfite soaking step is omitted, and the rest is the same as in Example 1.

[0114] Test Example 1

[0115] The surfaces of the reverse osmosis membranes obtained in Examples 1-9 and Comparative Examples 1-5 were observed using a scanning electron microscope. Figure 1 and Figure 2 ,from Figure 1 It can be seen that the membrane surfaces of Examples 1-9 all exhibit larger "leaf" structures. This structure, promoted by the co-solvent method, greatly improves the water flux of the reverse osmosis membrane.

[0116] Test Example 2

[0117] To test the performance of the reverse osmosis membranes obtained in Examples 1-9 and Comparative Examples 1-5, a cross-flow filtration apparatus was used to measure water flux and salt retention. The effective membrane area of a single rectangular test unit was 42 cm². A sodium chloride solution with a mass concentration of 32 g / L (3.2 wt%) was used as the feed solution, and the feed temperature was controlled at 25.0 ± 0.2°C. A pre-pressing treatment was performed at an operating pressure of 800 psi (5.5 MPa) for 3 hours, followed by a 30-minute filtrate collection. The volume of filtrate produced per unit time and per unit membrane area is the water flux (LMH). Salt retention (%) is calculated as (feed conductivity - filtrate conductivity) / feed conductivity. The water flux and salt retention results for each reverse osmosis membrane are shown in Table 1.

[0118] Table 1 Water flux and salt rejection of reverse osmosis membranes of different embodiments and comparative examples

[0119]

[0120] Combining the Examples and Comparative Examples, it can be seen that when only an aqueous co-solvent is added without an oil co-solvent, the reverse osmosis membrane flux and salt retention rate obtained by post-treatment with nitrous acid and sodium bisulfite are not high; when only an oil co-solvent is added without an aqueous co-solvent, the reverse osmosis membrane flux obtained by post-treatment with nitrous acid and sodium bisulfite is high, but the salt retention rate is low. When only both aqueous and oil co-solvents are present, the reverse osmosis membrane flux and salt retention rate obtained by post-treatment with nitrous acid and sodium bisulfite are both very high.

[0121] Finally, it should be noted that the above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the same. The basic principles and main features of the present invention have been described above using specific implementation schemes. Modifications or substitutions may be made based on the present invention, but such modifications or substitutions do not detract from the essence of the corresponding technical solutions from the scope of protection claimed by the present invention.

Claims

1. A method for preparing a high-flux, high-salt rejection reverse osmosis membrane, characterized in that: The porous base membrane is contacted with an aqueous solution and an oily solution in sequence to generate an interfacial polymerization reaction to form a nascent reverse osmosis membrane, and the nascent reverse osmosis membrane is contacted with a nitrous acid solution or a salt thereof and a hydrogen sulfite solution in sequence to obtain the high-flux and high-salt rejection reverse osmosis membrane; the aqueous solution contains an aqueous co-solvent, the concentration of the aqueous co-solvent in the aqueous solution is 1-95wt%, and the oily solution contains an oily co-solvent; the aqueous co-solvent is one or more of an alcohol solvent, a ketone solvent, and an ether solvent that is miscible with water but does not react with amino groups; and the oily co-solvent is one or more of an ester solvent, a ketone solvent, and an ether solvent that is miscible with an alkane solvent but does not react with acyl chlorides.

2. The preparation method according to claim 1, characterized in that The aqueous phase solution comprises polyamine monomers, aqueous phase co-solvents and water, and the oil phase solution comprises polyacyl chloride monomers, oil phase co-solvents and alkane solvents.

3. The preparation method according to claim 1, characterized in that The concentration of the oil phase co-solvent in the oil phase solution is 0.01-20 wt %.

4. The preparation method according to claim 1, characterized in that The aqueous phase co-solvent is selected from one or more of ethanol, n-propanol, isopropanol, ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, glycerol, acetone, methyl ethyl ketone, ethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, and diethylene glycol ethyl ether acetate; the oil phase co-solvent is selected from one or more of ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, and methyl butyrate. , ethyl butyrate, propyl butyrate, butyl butyrate, dimethyl oxalate, diethyl oxalate, dipropyl oxalate, dimethyl malonate, diethyl malonate, dimethyl succinate, diethyl succinate, acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, diethylene glycol dibutyl ether, diethylene glycol ethyl ether acetate, diethylene glycol ethyl ether butyrate, diethylene glycol diacetate, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether or one or more.

5. The preparation method according to claim 1, characterized in that The concentration of nitrite in the nitrous acid or its salt solution is 0.005-5wt%, the solution temperature is 4-50°C, and the pH is 1-7; the time for the primary reverse osmosis membrane to contact the nitrous acid or its salt solution is 5-1800s; the concentration of the hydrosulfite solution is 0.05-5wt%, the temperature is 4-50°C, and the pH is 1-7; the time for the reverse osmosis membrane treated with the nitrous acid or its salt solution to contact the hydrosulfite solution is 5-1800s.

6. The method for preparing a high-flux, high-salt rejection reverse osmosis membrane according to claim 1, wherein: The contact time between the porous base membrane surface and the aqueous solution is 1-300s; the interfacial polymerization reaction time is 1-300s.

7. The method for preparing a high-flux, high-salt rejection reverse osmosis membrane according to claim 2, wherein: The concentration of the polyamine monomer in the aqueous solution is 0.5-5wt%; the polyamine monomer is selected from one or more of o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 1,3,5-triaminobenzene, diaminotoluene, biphenylenediamine, and diaminonaphthalene; the concentration of the polyacyl chloride monomer in the oil phase solution is 0.01-5wt%; the polyacyl chloride monomer is selected from one or more of trimesoyl chloride, terephthaloyl chloride, isophthaloyl chloride, biphenyl dicarboxylic acid chloride, biphenyl trimesoyl chloride, biphenyl tetracarboxylic acid chloride, naphthalene dicarboxylic acid chloride, naphthalene trimesoyl chloride, naphthalene tetracarboxylic acid chloride, malonyl chloride, succinyl chloride, glutaryl chloride, and adipoyl chloride; the alkane solvent is selected from one or more of hexane, heptane, octane, nonane, decane, undecane, dodecane, Isopar C, Isopar E, Isopar G, Isopar H, Isopar L, and Isopar M.

8. The method for preparing a high-flux, high-salt rejection reverse osmosis membrane according to claim 1, wherein: The material of the porous base membrane is selected from one of polysulfone, polyethersulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyethylene, polypropylene, polyimide, polyetherimide, polyacrylonitrile, polyphenylene ether, polyphenylene sulfide, polyetherketone, and polyaryletherketone.

9. A high flux and high salt rejection reverse osmosis membrane, characterized in that: The preparation method is described in any one of claims 1 to 8.

10. Use of the high-flux, high-salt rejection reverse osmosis membrane according to claim 9 in the field of water treatment.

Images