A kind of middle-high pressure reverse osmosis membrane and its preparation method

Abstract

This invention relates to the field of membrane separation technology, and more particularly to a medium-high pressure reverse osmosis membrane and its preparation method. The preparation method includes: A) immersing a porous support membrane in an aqueous solution at 14–18°C, drying it at 60–80°C using a heated roller, and then further drying it; the aqueous solution includes polyamine monomers, N-methylpyrrolidone, N-N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water; B) immersing the porous support membrane obtained in step A) in an oil solution, removing it, and then heat-treating it to obtain a medium-high pressure reverse osmosis membrane; the oil solution includes acyl chloride monomers and an organic solvent. After the treatment in step A), the gas solubility in the droplets of the aqueous solution reaches saturation, adsorbing onto the surface of the porous support membrane to form nanobubbles. Then, through interfacial polymerization and heat treatment, a leaf-like pleated structure can be formed, improving membrane flux and desalination rate.

Description

Technical Field

[0001] This invention relates to the field of membrane separation technology, and in particular to a medium- and high-pressure reverse osmosis membrane and its preparation method. Background Technology

[0002] Composite medium- and high-pressure reverse osmosis membranes generally consist of a nonwoven fabric layer, a porous support layer, and a separation layer. Currently, the most commonly used porous support layer is formed on the surface of the nonwoven fabric layer using polysulfone / DMF via phase inversion. The separation layer is formed on the porous support layer via interfacial polymerization of m-phenylenediamine and trimesoyl chloride. The separation layer determines the separation performance of the composite membrane, while the bottom membrane primarily provides mechanical strength. The performance of composite medium- and high-pressure reverse osmosis membranes is mainly determined by the structure and chemical properties of the separation layer; therefore, the performance of the composite membrane can be designed by changing the structure of the separation layer.

[0003] Currently, in the production of medium and high pressure reverse osmosis membranes, performance is generally improved mainly through formulation, but it is not possible to simultaneously consider the membrane flux and desalination rate. Often, flux is sacrificed in order to ensure the membrane desalination rate. Summary of the Invention

[0004] In view of this, the technical problem to be solved by the present invention is to provide a medium-high pressure reverse osmosis membrane and its preparation method, which has better desalination rate and water flux.

[0005] This invention provides a method for preparing a medium-to-high pressure reverse osmosis membrane, comprising the following steps:

[0006] A) The porous support membrane is immersed in an aqueous solution at 14–18°C, dried at 60–80°C using heated rollers, and then further dried.

[0007] The aqueous solution comprises a polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water;

[0008] B) Immerse the porous support membrane obtained in step A) in an oil phase solution, remove it, and perform heat treatment to obtain a medium- and high-pressure reverse osmosis membrane;

[0009] The oil phase solution comprises acyl chloride monomers and organic solvents.

[0010] Preferably, in step A), the aqueous solution contains 1% to 4% by mass of polyamine monomer, 0.1% to 3% by mass of N-methylpyrrolidone, 0.1% to 3% by mass of N,N-dimethylacetamide, 0.01% to 0.3% by mass of sodium dodecylbenzenesulfonate, and 0.1% to 4% by mass of sodium bicarbonate.

[0011] The polyamine monomer is m-phenylenediamine.

[0012] Preferably, in step A), the pH value of the aqueous solution is 7 to 9.

[0013] Preferably, in step A), the soaking time is 5 to 120 seconds.

[0014] Preferably, in step A), the drying time using the heated roller is 0.5 to 10 minutes;

[0015] The drying temperature is 60-80℃ and the time is 1-2 minutes.

[0016] Preferably, in step B), the acyl chloride monomer includes pyromellitic acid trimethylolpropionate chloride and / or adipyl chloride;

[0017] The organic solvent includes at least one of n-hexane, Isopar G, and Isopar L.

[0018] Preferably, in step B), the mass concentration of the oil phase solution is 0.1% to 4%.

[0019] The soaking time is 5 to 120 seconds.

[0020] Preferably, in step B), the heat treatment temperature is 40–80°C and the time is 1–10 min.

[0021] Preferably, in step B), after the heat treatment, the process further includes rinsing;

[0022] The rinsing includes:

[0023] a1) Rinse with water at 20–40°C for 0.5–1 minute;

[0024] a2) Rinse with an IPA aqueous solution at a temperature of 60-70℃ and a mass concentration of 1%-2% for 4-5 minutes;

[0025] a3) Rinse with water at 20–40°C for 0.5–1 minute;

[0026] a4) Rinse with a citric acid aqueous solution at a temperature of 60-70℃ and a mass concentration of 1%-2% for 4-5 minutes;

[0027] a5) Rinse with water at 20–40°C for 0.5–1 minute;

[0028] a6) Rinse with a glycerol aqueous solution at a temperature of 20-30℃ and a mass concentration of 4%-5% for 2-3 minutes.

[0029] The present invention also provides a medium- and high-pressure reverse osmosis membrane prepared by the preparation method described above.

[0030] This invention provides a method for preparing a medium- and high-pressure reverse osmosis membrane, comprising the following steps: A) immersing a porous support membrane in an aqueous solution at 14–18°C, drying it at 60–80°C using a heated roller, and then further drying it; the aqueous solution comprises a polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water; B) immersing the porous support membrane obtained in step A) in an oil phase solution, removing it, and then heat-treating it to obtain a medium- and high-pressure reverse osmosis membrane; the oil phase solution comprises an acyl chloride monomer and an organic solvent. This invention uses an aqueous solution with specific components. The porous support membrane is first immersed in a low-temperature aqueous solution, then dried at 60–80°C using a heated roller. After the gas solubility in the aqueous solution droplets decreases to saturation, it adsorbs onto the surface of the porous support membrane to form nanobubbles. During the interfacial polymerization reaction, the nanobubbles are released under the reaction action, forming cavities within the separation layer. After the membrane is dried, the cavities dehydrate to form a leaf-like pleated structure, thereby improving the membrane flux. Aqueous solutions with specific components can further ensure the desalination rate of the membrane and prevent air bubbles from damaging the separation layer.

[0031] Experimental results show that the medium- and high-pressure reverse osmosis membrane prepared in this invention has a desalination rate of no less than 99.69% and a water flux of no less than 29.7 GFD for a 4000 mg / L NaCl aqueous solution under the conditions of temperature 25 ± 0.5℃, pH value 7.0 ± 0.5, and test pressure 2.21 MPa. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides a method for preparing a medium-to-high pressure reverse osmosis membrane, comprising the following steps:

[0034] A) The porous support membrane is immersed in an aqueous solution at 14–18°C, dried at 60–80°C using heated rollers, and then further dried.

[0035] The aqueous solution comprises a polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water;

[0036] B) Immerse the porous support membrane obtained in step A) in an oil phase solution, remove it, and perform heat treatment to obtain a medium- and high-pressure reverse osmosis membrane;

[0037] The oil phase solution comprises acyl chloride monomers and organic solvents.

[0038] In step A):

[0039] The porous support membrane is immersed in an aqueous solution at 14–18°C, dried at 60–80°C using heated rollers, and then further dried.

[0040] In some embodiments of the present invention, the porous support membrane is a polysulfone porous support membrane, obtained by composite of polysulfone and nonwoven fabric. Specifically, the preparation method of the polysulfone porous support membrane includes:

[0041] b1) Dissolve polysulfone in N,N-dimethylformamide (DMF), filter, and obtain a polysulfone solution;

[0042] b2) The polysulfone solution is uniformly coated onto a nonwoven fabric and immersed in a coagulation bath. After coagulation, a polysulfone porous support membrane is obtained.

[0043] In step b1):

[0044] The mass ratio of polysulfone to N,N-dimethylformamide is 1:3.76 to 6.69; specifically, it is 1:4.26.

[0045] The filtration process uses a filter screen with a pore size of 20–30 μm, specifically 20 μm. A stainless steel filter screen is used to remove solid impurities. After filtration, the process further includes degassing and cooling to room temperature. The degassing is performed in a vacuum drying oven.

[0046] In step b2):

[0047] The coating amount of the polysulfone solution is 110–180 g / m². 2 Specifically, it can be 140g / m 2 .

[0048] The temperature of the coagulation bath is 14–25°C, specifically 25°C; the time is 5 minutes. The coagulation bath is a deionized water coagulation bath.

[0049] After solidification, the process also includes rinsing with deionized water.

[0050] After obtaining the porous support membrane, the porous support membrane is immersed in an aqueous solution at 14-18℃, dried at 60-80℃ using a heated roller, and then further dried.

[0051] The aqueous solution comprises a polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water. In some embodiments, the polyamine monomer is m-phenylenediamine. The water is deionized water.

[0052] In some embodiments of the present invention, the aqueous solution contains 1% to 4% by mass of the polyamine monomer, 0.1% to 3% by mass of N-methylpyrrolidone, 0.1% to 3% by mass of N,N-dimethylacetamide, 0.01% to 0.3% by mass of sodium dodecylbenzenesulfonate, and 0.1% to 4% by mass of sodium bicarbonate. In some embodiments of the present invention, the aqueous solution contains 2% by mass of the polyamine monomer, 1% or 0.5% by mass of N-methylpyrrolidone, 0.5% or 0.2% by mass of N,N-dimethylacetamide, 0.1% or 0.2% by mass of sodium dodecylbenzenesulfonate, and 1% or 1.5% by mass of sodium bicarbonate.

[0053] The pH value of the aqueous solution is 7 to 9; specifically, it can be 8.

[0054] In some embodiments of the present invention, the method for preparing the aqueous solution includes:

[0055] The polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate and water were mixed and stirred to dissolve. Sodium hydroxide was added to adjust the pH of the resulting solution to 7-9, thus obtaining an aqueous solution.

[0056] In some embodiments of the present invention, the temperature of the aqueous solution is 17°C or 14°C.

[0057] In some embodiments of the present invention, the soaking time is 5 to 120 seconds; specifically, it can be 30 seconds.

[0058] In some embodiments of the present invention, the temperature of the heated roller drying is 60°C or 80°C; the time is 0.5 to 10 minutes; specifically, it can be 2 minutes.

[0059] In some embodiments of the present invention, the drying temperature is 60–80°C, specifically 70°C or 80°C; the drying time is 1–2 minutes, specifically 1 minute. The drying is carried out in an oven.

[0060] In step B):

[0061] The porous support membrane obtained in step A) is immersed in an oil phase solution, and after being taken out, it is subjected to heat treatment to obtain a medium- and high-pressure reverse osmosis membrane.

[0062] The oil phase solution comprises acyl chloride monomers and organic solvents.

[0063] In some embodiments of the present invention, the acyl chloride monomer comprises trimesoyl chloride and / or adipic acid chloride. The organic solvent comprises at least one selected from n-hexane, Isopar G, and Isopar L; preferably n-hexane. The mass concentration of the oil phase solution is 0.1% to 4%; specifically 0.2%.

[0064] In some embodiments of the present invention, the method for preparing the oil phase solution includes:

[0065] The acyl chloride monomer and organic solvent are mixed and stirred to dissolve, resulting in an oil phase solution.

[0066] In some embodiments of the present invention, the soaking time is 5 to 120 seconds; specifically, 30 seconds.

[0067] In some embodiments of the present invention, after removal, the oil phase solution on the surface of the porous support membrane is drained.

[0068] In some embodiments of the present invention, the heat treatment temperature is 40–80°C, specifically 80°C; the time is 1–10 min, specifically 5 min. The heat treatment is carried out in an oven.

[0069] In some embodiments of the present invention, the heat treatment process further includes rinsing;

[0070] The rinsing includes:

[0071] a1) Rinse with water at 20–40°C for 0.5–1 minute;

[0072] a2) Rinse with an IPA aqueous solution at a temperature of 60-70℃ and a mass concentration of 1%-2% for 4-5 minutes;

[0073] a3) Rinse with water at 20–40°C for 0.5–1 minute;

[0074] a4) Rinse with a citric acid aqueous solution at a temperature of 60-70℃ and a mass concentration of 1%-2% for 4-5 minutes;

[0075] a5) Rinse with water at 20–40°C for 0.5–1 minute;

[0076] a6) Rinse with a glycerol aqueous solution at a temperature of 20-30℃ and a mass concentration of 4%-5% for 2-3 minutes.

[0077] In some embodiments of the present invention, in step a1), the water temperature is 30°C and the rinsing time is 0.8 min.

[0078] In some embodiments of the present invention, in step a2), the temperature of the IPA aqueous solution is 65°C, the mass concentration is 1.5%, and the rinsing time is 4 min.

[0079] In some embodiments of the present invention, in step a3), the water temperature is 30°C and the rinsing time is 0.8 min.

[0080] In some embodiments of the present invention, in step a4), the temperature of the citric acid aqueous solution is 65°C, the mass concentration is 1.5%, and the rinsing time is 4 min.

[0081] In some embodiments of the present invention, in step a5), the water temperature is 30°C and the rinsing time is 0.8 min.

[0082] In some embodiments of the present invention, in step a6), the temperature of the glycerol aqueous solution is 25°C, the mass concentration is 4.5%, and the rinsing time is 2 min.

[0083] After rinsing, the process also includes drying.

[0084] The present invention does not impose any special restrictions on the source of the raw materials used above, and they can be commercially available.

[0085] The present invention also provides a medium- and high-pressure reverse osmosis membrane prepared by the preparation method described above.

[0086] Beneficial effects:

[0087] This invention employs an aqueous solution with specific components. A porous support membrane is first immersed in the low-temperature aqueous solution, then dried at 60–80°C using a heated roller. As the gas solubility in the aqueous solution droplets decreases to saturation, the gas is adsorbed onto the surface of the porous support membrane, forming nanobubbles. During interfacial polymerization, these nanobubbles are released and form cavities within the separation layer. After drying, the cavities dehydrate, forming a leaf-like pleated structure, thereby increasing the membrane flux. The specific components of the aqueous solution further ensure the membrane's desalination rate and prevent the bubbles from damaging the separation layer.

[0088] In the preparation method of medium and high pressure reverse osmosis membrane provided by the present invention, the porous support membrane is first soaked in a low temperature aqueous solution, and then dried and baked at 60-80°C using a heating roller. It can be soaked in an oil phase solution without the need for vacuum water removal.

[0089] To further illustrate the present invention, the following detailed description of a medium-high pressure reverse osmosis membrane and its preparation method provided by the present invention is provided in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0090] All reagents used in the following examples are commercially available.

[0091] Comparative Example 1

[0092] 1) Preparation of polysulfone porous supported membrane:

[0093] 95g of polysulfone was dissolved in 405g of N,N-dimethylformamide (DMF), filtered through a stainless steel filter with a pore size of 20μm, degassed in a vacuum drying oven, and cooled to room temperature to obtain a polysulfone solution.

[0094] The polysulfone solution was uniformly coated onto a nonwoven fabric at a coating amount of 150 g / m². 2 The membrane was immersed in a deionized water coagulation bath (the temperature of the coagulation bath was 25℃ and the time was 5min). After coagulation, it was rinsed with deionized water to obtain a polysulfone porous support membrane.

[0095] 2) Preparation of aqueous solutions:

[0096] Weigh out 10g of m-phenylenediamine, 5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide and 482.5g of deionized water, mix them, stir to dissolve, add sodium hydroxide to adjust the pH of the resulting solution to 8, and obtain an aqueous solution.

[0097] Preparation of oil phase solution:

[0098] 1.2 g of pyromellitic acid chloride and 600 g of n-hexane were mixed and stirred to dissolve, resulting in an oil phase solution.

[0099] 3) Immerse the polysulfone porous support membrane in an aqueous solution at 25°C for 30 seconds, and then dry the aqueous solution with an air knife at 25°C.

[0100] 4) The obtained porous support membrane is immersed in the oil phase solution for 30 seconds. After taking it out, the oil phase solution on the surface of the porous support membrane is drained, and then heat-treated in an oven at 80℃ for 5 minutes.

[0101] 5) Rinsing:

[0102] Rinse with 30℃ water for 0.8 minutes;

[0103] Rinse with an IPA aqueous solution at 65℃ and a mass concentration of 1.5% for 4 minutes;

[0104] Rinse with 30℃ water for 0.8 minutes;

[0105] Rinse with a citric acid aqueous solution at 65℃ and a mass concentration of 1.5% for 4 minutes;

[0106] Rinse with 30℃ water for 0.8 minutes;

[0107] Rinse with a 4.5% glycerol aqueous solution at 25°C for 2 minutes;

[0108] After rinsing, the membrane is dried to obtain a medium-high pressure reverse osmosis membrane.

[0109] Example 1

[0110] 1) Preparation of polysulfone porous supported membrane:

[0111] 95g of polysulfone was dissolved in 405g of N,N-dimethylformamide (DMF), filtered through a stainless steel filter with a pore size of 20μm, degassed in a vacuum drying oven, and cooled to room temperature to obtain a polysulfone solution.

[0112] The polysulfone solution was uniformly coated onto a nonwoven fabric at a coating weight of 140 g / m². 2 The membrane was immersed in a deionized water coagulation bath (the temperature of the coagulation bath was 25℃ and the time was 5min). After coagulation, it was rinsed with deionized water to obtain a polysulfone porous support membrane.

[0113] 2) Preparation of aqueous solutions:

[0114] Weigh out 10g of m-phenylenediamine, 5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 0.5g of sodium dodecylbenzenesulfonate, 5g of sodium bicarbonate and 479.5g of deionized water, mix them and stir to dissolve. Add sodium hydroxide to adjust the pH of the resulting solution to 8 to obtain an aqueous solution.

[0115] Preparation of oil phase solution:

[0116] 1.2 g of pyromellitic acid chloride and 600 g of n-hexane were mixed and stirred to dissolve, resulting in an oil phase solution.

[0117] 3) The polysulfone porous support membrane is immersed in an aqueous solution at 17°C for 30 seconds, dried at 60°C for 2 minutes using a heated roller, and then dried in an oven at 70°C for 1 minute.

[0118] 4) The obtained porous support membrane is immersed in the oil phase solution for 30 seconds. After taking it out, the oil phase solution on the surface of the porous support membrane is drained, and then heat-treated in an oven at 80℃ for 5 minutes.

[0119] 5) Rinsing:

[0120] Rinse with 30℃ water for 0.8 minutes;

[0121] Rinse with an IPA aqueous solution at 65℃ and a mass concentration of 1.5% for 4 minutes;

[0122] Rinse with 30℃ water for 0.8 minutes;

[0123] Rinse with a citric acid aqueous solution at 65℃ and a mass concentration of 1.5% for 4 minutes;

[0124] Rinse with 30℃ water for 0.8 minutes;

[0125] Rinse with a 4.5% glycerol aqueous solution at 25°C for 2 minutes;

[0126] After rinsing, the membrane is dried to obtain a medium-high pressure reverse osmosis membrane.

[0127] Example 2

[0128] The difference from Example 1 is as follows:

[0129] In the preparation of the aqueous solution in step 2):

[0130] Weigh out 10g of m-phenylenediamine, 5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 0.5g of sodium dodecylbenzenesulfonate, 7.5g of sodium bicarbonate and 474.5g of deionized water, mix them, stir to dissolve, add sodium hydroxide to adjust the pH of the resulting solution to 8, and obtain an aqueous solution.

[0131] The remaining steps and parameters are the same as in Example 1, and a medium-high pressure reverse osmosis membrane is obtained.

[0132] Example 3

[0133] The difference from Example 1 is as follows:

[0134] In the preparation of the aqueous solution in step 2):

[0135] Weigh out 10g of m-phenylenediamine, 2.5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 1g of sodium dodecylbenzenesulfonate, 5g of sodium bicarbonate and 479g of deionized water, mix them and stir to dissolve. Add sodium hydroxide to adjust the pH of the resulting solution to 8 to obtain an aqueous solution.

[0136] The remaining steps and parameters are the same as in Example 1, and a medium-high pressure reverse osmosis membrane is obtained.

[0137] Example 4

[0138] The difference from Example 1 is as follows:

[0139] In the preparation of the aqueous solution in step 2):

[0140] Weigh out 10g of m-phenylenediamine, 2.5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 0.5g of sodium dodecylbenzenesulfonate, 5g of sodium bicarbonate and 479.5g of deionized water, mix them and stir to dissolve. Add sodium hydroxide to adjust the pH of the resulting solution to 8 to obtain an aqueous solution.

[0141] In step 3): the polysulfone porous support membrane is immersed in an aqueous solution at 14°C for 30 seconds, dried at 80°C for 2 minutes using a heated roller, and then dried in an oven at 80°C for 1 minute.

[0142] The remaining steps and parameters are the same as in Example 1, and a medium-high pressure reverse osmosis membrane is obtained.

[0143] Example 5

[0144] The difference from Example 1 is as follows:

[0145] In the preparation of the aqueous solution in step 2):

[0146] Weigh out 10g of m-phenylenediamine, 5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 0.5g of sodium dodecylbenzenesulfonate, 7.5g of sodium bicarbonate and 474.5g of deionized water, mix them, stir to dissolve, add sodium hydroxide to adjust the pH of the resulting solution to 8, and obtain an aqueous solution.

[0147] In step 3): the polysulfone porous support membrane is immersed in an aqueous solution at 14°C for 30 seconds, dried at 80°C for 2 minutes using a heated roller, and then dried in an oven at 80°C for 1 minute.

[0148] The remaining steps and parameters are the same as in Example 1, and a medium-high pressure reverse osmosis membrane is obtained.

[0149] Example 6

[0150] The difference from Example 1 is as follows:

[0151] In the preparation of the aqueous solution in step 2):

[0152] Weigh out 10g of m-phenylenediamine, 5g of N-methylpyrrolidone, 2.5g of N,N-dimethylacetamide, 1g of sodium dodecylbenzenesulfonate, 7.5g of sodium bicarbonate and 474g of deionized water, mix them, stir to dissolve, add sodium hydroxide to adjust the pH of the resulting solution to 8, and obtain an aqueous solution.

[0153] In step 3): the polysulfone porous support membrane is immersed in an aqueous solution at 14°C for 30 seconds, dried at 80°C for 2 minutes using a heated roller, and then dried in an oven at 80°C for 1 minute.

[0154] The remaining steps and parameters are the same as in Example 1, and a medium-high pressure reverse osmosis membrane is obtained.

[0155] Comparative Example 2

[0156] The difference from Example 1 is as follows:

[0157] In step 3):

[0158] The polysulfone porous support membrane was immersed in an aqueous solution at 25°C for 30 seconds, dried at 60°C for 2 minutes using a heated roller, and then dried in an oven at 70°C for 1 minute.

[0159] Comparative Example 3

[0160] The difference from Example 1 is as follows:

[0161] In step 3):

[0162] The polysulfone porous support membrane was immersed in an aqueous solution at 25°C for 30 seconds and then dried in an oven at 70°C for 3 minutes.

[0163] The performance of the medium- and high-pressure reverse osmosis membranes prepared in Comparative Example 1 and Examples 1-6 was tested:

[0164] Table 1 shows the desalination rate and water flux of the medium- and high-pressure reverse osmosis membrane for a 4000 mg / L NaCl aqueous solution under the conditions of temperature 25 ± 0.5℃, pH 7.0 ± 0.5, and test pressure 2.21 MPa.

[0165] Membrane flux / GFD Membrane desalination rate / % Comparative Example 1 23.6 99.35 Example 1 30.8 99.69 Example 2 32.1 99.71 Example 3 29.7 99.77 Example 4 31.9 99.73 Example 5 33.9 99.74 Example 6 34.8 99.72 Comparative Example 2 27.8 99.53 Comparative Example 3 25.5 99.42

[0166] Experimental results show that the medium-high pressure reverse osmosis membrane prepared in this invention has a desalination rate of not less than 99.69% and a water flux of not less than 29.7 GFD for a 4000 mg / L NaCl aqueous solution under the conditions of temperature 25 ± 0.5℃ and test pressure 2.21 MPa.

[0167] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a medium-to-high pressure reverse osmosis membrane, comprising the following steps: A) The porous support membrane is immersed in an aqueous solution at 14~18℃, dried at 60~80℃ using a heated roller, and then further dried. The aqueous solution comprises a polyamine monomer, N-methylpyrrolidone, N,N-dimethylacetamide, sodium dodecylbenzenesulfonate, sodium bicarbonate, sodium hydroxide, and water; B) The porous support membrane obtained in step A) can be immersed in the oil phase solution without the need for vacuum water removal. After removal, it is heat-treated to obtain a medium-high pressure reverse osmosis membrane with a leaf-shaped pleated structure. The oil phase solution comprises acyl chloride monomers and organic solvents.

2. The preparation method according to claim 1, characterized in that, In step A), the aqueous solution contains 1%–4% by mass of polyamine monomer, 0.1%–3% by mass of N-methylpyrrolidone, 0.1%–3% by mass of N,N-dimethylacetamide, 0.01%–0.3% by mass of sodium dodecylbenzenesulfonate, and 0.1%–4% by mass of sodium bicarbonate. The polyamine monomer is m-phenylenediamine.

3. The preparation method according to claim 1, characterized in that, In step A), the pH value of the aqueous solution is 7~9.

4. The method of claim 1, wherein, In step A), the soaking time is 5~120s.

5. The preparation method according to claim 1, characterized in that, In step A), the drying time using heated rollers is 0.5~10 min; The drying temperature is 60~80℃ and the time is 1~2 min.

6. The method of claim 1, wherein, In step B), the acyl chloride monomer includes pyromellitic acid trimethylolpropionate chloride and / or adipoyl chloride; The organic solvent includes at least one of n-hexane, Isopar G, and Isopar L.

7. The preparation method according to claim 1, characterized in that, In step B), the mass concentration of the oil phase solution is 0.1% to 4%. The soaking time is 5~120 s.

8. The method of claim 1, wherein, In step B), the heat treatment temperature is 40~80℃ and the time is 1~10 min.

9. The preparation method according to claim 1, characterized in that, In step B), after the heat treatment, the process further includes rinsing; The rinsing includes: a1) Rinse with water at 20~40℃ for 0.5~1 min; a2) Rinse with an IPA aqueous solution at a temperature of 60~70℃ and a mass concentration of 1%~2% for 4~5 minutes; a3) Rinse with water at 20~40℃ for 0.5~1 min; a4) Rinse with a citric acid aqueous solution at a temperature of 60~70℃ and a mass concentration of 1%~2% for 4~5 minutes; a5) Rinse with water at 20~40℃ for 0.5~1 min; a6) Rinse with a glycerol aqueous solution at a temperature of 20~30℃ and a mass concentration of 4%~5% for 2~3 minutes.

10. The medium- and high-pressure reverse osmosis membrane prepared by the preparation method according to any one of claims 1 to 9.