A method for preparing a seawater desalination membrane

Abstract

The present application belongs to the field of separation membrane, and particularly relates to a preparation method of a seawater desalination membrane, comprising the following steps: a) providing a base membrane; b) coating an ionic liquid containing a polyamine monomer on the front surface of the base membrane, and then drying to surface dryness of the base membrane; c) coating an ionic liquid containing a polyacyl chloride monomer on the surface-dried base membrane, and then performing a drying treatment to obtain a nascent polyamide separation membrane; d) sequentially immersing the nascent polyamide separation membrane in treatment liquids containing m-phenylenediamine and sodium metabisulfite at high temperature; e) sequentially performing water washing and glycerol aqueous solution immersion on the separation membrane treated in step d), and then coating a polyvinyl alcohol solution on the front surface of the separation membrane, and drying to obtain a seawater desalination membrane. The seawater desalination membrane prepared by the method has good initial performance and stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of separation membranes, and particularly relates to a preparation method of a seawater desalination membrane. BACKGROUND

[0002] The seawater desalination membrane is generally composed of a non-woven fabric layer, a porous support layer and a separation layer. The porous support layer currently used more is formed on the surface of the non-woven fabric layer by phase inversion of polysulfone / DMF, and the separation layer is formed on the porous support layer by interfacial polymerization of polyamine monomers and polyacyl chloride monomers. The separation performance of the seawater desalination membrane is mainly determined by the structure (pore size, porosity, thickness, roughness, surface charge and hydrophilicity, etc.) and the chemical properties (functional groups, bond energy, crosslinking degree, etc.) of the separation layer, so that the separation performance of the seawater desalination membrane can be regulated by controlling the interfacial polymerization process of the polyamine monomers and the polyacyl chloride monomers.

[0003] The seawater desalination membrane is a product mainly used in high-salt and high-pressure environments, and has high requirements for the separation performance and long-term stability of the membrane. However, the existing preparation method cannot effectively control the interfacial polymerization process of the polyamine monomers and the polyacyl chloride monomers, resulting in obvious deficiencies in the initial performance and stability of the membrane. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a preparation method of a seawater desalination membrane, and the seawater desalination membrane prepared by the method has good initial performance and stability.

[0005] The present application provides a preparation method of a seawater desalination membrane, comprising the following steps:

[0006] a) providing a base membrane;

[0007] In step a), the front surface of the base membrane is a porous support layer, and the back surface is a non-woven fabric layer;

[0008] b) coating a polyamine monomer solution on the front surface of the base membrane, and then drying to a dry-to-the-touch state;

[0009] In step b), the solvent of the polyamine monomer solution is imidazole acetate ionic liquid;

[0010] c) coating a polyacyl chloride monomer solution on the front surface of the base membrane in the dry-to-the-touch state to perform interfacial polymerization, and then performing drying treatment to obtain a nascent polyamide separation membrane;

[0011] In step c), the solvent of the polyacyl chloride monomer solution is one or more of 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bis-trifluoromethylsulfonylimide and 1-butyl-3-methylimidazolium trifluoromethanesulfonate;

[0012] d) sequentially immersing the nascent polyamide separation membrane in a first treatment solution and a second treatment solution;

[0013] In step d), the components of the first treatment solution include m-phenylenediamine and 1-pentyl-3-methylimidazolium acetate; the components of the second treatment solution include sodium pyrosulfite; the temperature of the immersion in the first treatment solution and the second treatment solution is 60-80°C;

[0014] e) sequentially immersing the separation membrane treated in step d) in water and glycerol aqueous solution, then coating a polyvinyl alcohol solution on the front side of the separation membrane, drying to obtain a seawater desalination membrane.

[0015] Preferably, in step b), the polyamine monomer in the polyamine monomer solution is m-phenylenediamine; the content of the polyamine monomer in the polyamine monomer solution is 1-4wt%.

[0016] Preferably, in step b), the imidazole acetate ionic liquid is 1-pentyl-3-methylimidazolium acetate.

[0017] Preferably, in step c), the polyacyl chloride monomer in the polyacyl chloride monomer solution is trimesoyl chloride and / or adipoyl chloride; the content of the polyacyl chloride monomer in the polyacyl chloride monomer solution is 0.2-0.4wt%.

[0018] Preferably, in step c), the temperature of the drying treatment is 60-100°C; the time of the drying treatment is 1-3min.

[0019] Preferably, in step d), the content of the m-phenylenediamine in the first treatment solution is 0.1-0.5wt%; the content of the 1-pentyl-3-methylimidazolium acetate in the first treatment solution is 1-5wt%; the content of the sodium pyrosulfite in the second treatment solution is 0.1-0.5wt%.

[0020] Preferably, in step d), the time of the immersion in the first treatment solution and the second treatment solution is 1-2min.

[0021] Preferably, in step e), the water washing process includes:

[0022] The first rinsing is performed in water at 40-60°C, the second rinsing is performed in water at 70-80°C, and the third rinsing is performed in water at 40-60°C.

[0023] Preferably, the first rinsing is performed for 0.5-1 min, the second rinsing is performed for 15-20 min, and the third rinsing is performed for 0.5-1 min.

[0024] Preferably, in step e), the glycerol content in the glycerol aqueous solution is 1-5 wt%, the glycerol aqueous solution is soaked at a temperature of 10-40°C for 2-3 min.

[0025] Compared with the prior art, the seawater desalination membrane preparation method provided by the application comprises the following steps: a) providing a base film; in step a), the front surface of the base film is a porous support layer, and the back surface is a non-woven fabric layer; b) coating a polyamine monomer solution on the front surface of the base film, and then drying to surface dryness; in step b), the solvent of the polyamine monomer solution is imidazole acetate ionic liquid; c) coating a polyacyl chloride monomer solution on the surface-dried front surface of the base film to perform an interfacial polymerization reaction, and then performing drying treatment to obtain a nascent polyamide separation membrane; in step c), the solvent of the polyacyl chloride monomer solution is one or more of 1-ethyl-3-methylimidazole tetrafluoroborate, 1-ethyl-3-methylimidazole dicyanamide, 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole bistrifluoromethanesulfonylimide and 1-butyl-3-methylimidazole trifluoromethanesulfonate; d) sequentially immersing the nascent polyamide separation membrane in a first treatment liquid and a second treatment liquid; in step d), the components of the first treatment liquid comprise m-phenylenediamine and 1-pentyl-3-methylimidazole acetate; the components of the second treatment liquid comprise sodium metabisulfite; the temperature for immersion in the first treatment liquid and the second treatment liquid is 60-80 DEG C; e) sequentially performing water washing and glycerol aqueous solution immersion on the separation membrane after step d) is completed, and then coating a polyvinyl alcohol solution on the front surface of the separation membrane, and drying to obtain a seawater desalination membrane. Through the optimized design of the seawater desalination membrane preparation method, especially the optimized selection of the solvent of the polyamine monomer solution and the polyacyl chloride monomer solution, the stability and controllability of the interfacial polymerization reaction can be improved, laying a foundation for the improvement of the separation performance of the membrane sheet. On this basis, by sequentially immersing the membrane sheet after the interfacial polymerization reaction in a high-temperature treatment liquid containing m-phenylenediamine and sodium metabisulfite, the performance of the membrane sheet is further improved. Specifically, immersion in the high-temperature treatment liquid containing m-phenylenediamine can cause secondary reaction on the surface of the membrane sheet, thereby avoiding potential structural defects caused by insufficient primary reaction; immersion in the high-temperature treatment liquid containing sodium metabisulfite can remove chlorine and prevent oxidation, further improving the stability of the membrane sheet. Through the optimized seawater desalination membrane preparation method, the nascent membrane after the interfacial polymerization can break through the Trade-off effect to a greater extent, so that the membrane sheet has good flux on the basis of maintaining high desalination rate; at the same time, this method effectively avoids potential structural defects on the surface of the membrane, improves the running stability of the membrane sheet, and has good industrial application prospect. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] The present application provides a preparation method of seawater desalination membrane, comprising the following steps:

[0028] a) providing a base membrane;

[0029] b) coating a polyamine monomer solution on the front surface of the base membrane, and then drying to surface dryness of the base membrane;

[0030] c) coating a polyacyl chloride monomer solution on the surface-dried base membrane to perform interfacial polymerization, and then performing drying treatment to obtain a nascent polyamide separation membrane;

[0031] d) sequentially immersing the nascent polyamide separation membrane in a first treatment liquid and a second treatment liquid;

[0032] e) sequentially performing water washing and glycerol aqueous solution immersion on the separation membrane treated in step d), and then coating a polyvinyl alcohol solution on the front surface of the separation membrane, drying to obtain a seawater desalination membrane.

[0033] In the preparation method provided by the present application, in step a), the front surface of the base membrane is a porous support layer, and the back surface is a non-woven fabric layer; wherein the composition of the porous support layer is preferably one or more of polysulfone, polyethersulfone and polyvinylidene fluoride; the average pore size of the porous support layer is preferably 10-50 nm, and can be specifically 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm or 50 nm; the thickness of the porous support layer is preferably 20-50 μm, and can be specifically 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm; the thickness of the non-woven fabric layer is preferably 80-120 μm, and can be specifically 80 μm, 85 μm, 90 μm, 95 μm, 100 μm, 105 μm, 110 μm, 115 μm or 120 μm.

[0034] In the preparation method provided by the application, in step b), the polyamine monomer in the polyamine monomer solution is preferably m-phenylenediamine; and the content of the polyamine monomer in the polyamine monomer solution is preferably 1-4 wt%, and specifically can be 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt% or 4 wt%.

[0035] In the preparation method provided by the application, in step b), the solvent of the polyamine monomer solution is imidazole acetate ionic liquid; and the imidazole acetate ionic liquid is preferably 1-pentyl-3-methyl imidazole acetate.

[0036] In the preparation method provided by the application, in step c), the polyacyl chloride monomer solution is coated on the surface of the base film, and interfacial polymerization is performed between the polyacyl chloride monomer solution and the polyamine monomer solution on the surface of the base film to form a polyamide layer, and then the polyamide layer is further crosslinked through drying treatment.

[0037] In the preparation method provided by the application, in step c), the polyacyl chloride monomer in the polyacyl chloride monomer solution is preferably trimesoyl chloride and / or adipoyl chloride; and the content of the polyacyl chloride monomer in the polyacyl chloride monomer solution is preferably 0.2-0.4 wt%, and specifically can be 0.2 wt%, 0.21 wt%, 0.22 wt%, 0.23 wt%, 0.24 wt%, 0.25 wt%, 0.26 wt%, 0.27 wt%, 0.28 wt%, 0.29 wt%, 0.3 wt%, 0.31 wt%, 0.32 wt%, 0.33 wt%, 0.34 wt%, 0.35 wt%, 0.36 wt%, 0.37 wt%, 0.38 wt%, 0.39 wt% or 0.4 wt%.

[0038] In the preparation method provided by the application, in step c), the solvent of the polyacyl chloride monomer solution is one or more of 1-ethyl-3-methyl imidazole tetrafluoroborate, 1-ethyl-3-methyl imidazole dicyanamide, 1-butyl-3-methyl imidazole tetrafluoroborate, 1-butyl-3-methyl imidazole hexafluorophosphate, 1-butyl-3-methyl imidazole bistrifluoromethylsulfonylimide and 1-butyl-3-methyl imidazole trifluoromethanesulfonate.

[0039] In the preparation method provided by the application, in step c), the coating amount of the polybasic acid chloride monomer solution is preferably 20-30 g / m 2 , specifically 20 g / m 2 , 21 g / m 2 , 22 g / m 2 , 23 g / m 2 , 24 g / m 2 , 25 g / m 2 , 26 g / m 2 , 27 g / m 2 , 28 g / m 2 , 29 g / m 2 or 30 g / m 2 .

[0040] In the preparation method provided by the application, in step c), the temperature of the drying treatment is preferably 60-100℃, specifically 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃; and the time of the drying treatment is preferably 1-3 min, specifically 1 min, 1.5 min, 2 min, 2.5 min or 3 min.

[0041] In the preparation method provided by the application, in step d), the components of the first treatment solution include m-phenylenediamine, 1-pentyl-3-methyl imidazole acetate and water; wherein the main role of the m-phenylenediamine is to react with the reactive groups on the surface of the membrane; the content of the m-phenylenediamine in the first treatment solution is preferably 0.1-0.5 wt%, specifically 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.35 wt%, 0.4 wt%, 0.45 wt% or 0.5 wt%; and the main role of the 1-pentyl-3-methyl imidazole acetate is to stabilize the reaction interface and promote the reaction; the content of the 1-pentyl-3-methyl imidazole acetate in the first treatment solution is preferably 1-5 wt%, specifically 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt% or 5 wt%.

[0042] In the preparation method provided by the application, in step d), the temperature for soaking in the first treatment solution is 60-80℃, specifically 60℃, 62℃, 65℃, 67℃, 70℃, 72℃, 75℃, 77℃ or 80℃; and the time for soaking in the first treatment solution is preferably 1-2 min, specifically 1 min, 1.1 min, 1.2 min, 1.3 min, 1.4 min, 1.5 min, 1.6 min, 1.7 min, 1.8 min, 1.9 min or 2 min.

[0043] In the preparation method provided by the application, in step d), the components of the second treatment solution include sodium metabisulfite and water; wherein the main role of the sodium metabisulfite is to remove chlorine and prevent oxidation; the content of the sodium metabisulfite in the second treatment solution is preferably 0.1-0.5wt%, and specifically can be 0.1wt%, 0.15wt%, 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt% or 0.5wt%.

[0044] In the preparation method provided by the application, in step d), the temperature for soaking in the second treatment solution is 60-80℃, and specifically can be 60℃, 62℃, 65℃, 67℃, 70℃, 72℃, 75℃, 77℃ or 80℃; the time for soaking in the second treatment solution is preferably 1-2min, and specifically can be 1min, 1.1min, 1.2min, 1.3min, 1.4min, 1.5min, 1.6min, 1.7min, 1.8min, 1.9min or 2min.

[0045] In the preparation method provided by the application, in step e), the specific process of the water washing preferably includes: first performing first rinsing in water at 40-60℃, then performing second rinsing in water at 70-80℃, and then performing third rinsing in water at 40-60℃; wherein the time for the first rinsing is preferably 0.5-1min, and specifically can be 0.5min, 0.6min, 0.7min, 0.8min, 0.9min or 1min; the time for the second rinsing is preferably 15-20min, and specifically can be 15min, 16min, 17min, 18min, 19min or 20min; the time for the third rinsing is preferably 0.5-1min, and specifically can be 0.5min, 0.6min, 0.7min, 0.8min, 0.9min or 1min.

[0046] In the preparation method provided by the application, in step e), the purpose of the glycerol aqueous solution soaking is to fill the pores of the separation membrane, so as to prevent the membrane pores from collapsing to cause structural changes and affect the performance in the subsequent drying and storage processes.

[0047] In the preparation method provided by the application, in step e), the content of glycerol in the glycerol aqueous solution is preferably 1-5wt%, and specifically can be 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%.

[0048] In the preparation method provided by the application, in step e), the temperature of the glycerol aqueous solution immersion is preferably 10-40℃, and can be specifically 10℃, 15℃, 20℃, 25℃ (room temperature), 30℃, 35℃ or 40℃; the time of the glycerol aqueous solution immersion is preferably 2-3 min, and can be specifically 2 min, 2.1 min, 2.2 min, 2.3 min, 2.4 min, 2.5 min, 2.6 min, 2.7 min, 2.8 min, 2.9 min or 3 min.

[0049] In the preparation method provided by the application, in step e), the purpose of the polyvinyl alcohol solution coating is to form a protective layer on the surface of the polyamide separation layer of the separation membrane to prevent damage to the membrane surface.

[0050] In the preparation method provided by the application, in step e), the number average molecular weight of the polyvinyl alcohol in the polyvinyl alcohol solution is preferably 10000-40000, more preferably 15000-30000, and most preferably 19800-26400; the concentration of the polyvinyl alcohol solution is preferably 0.5-5wt%, and can be specifically 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt% or 5wt%.

[0051] In the preparation method provided by the application, in step e), the dry coating amount of the polyvinyl alcohol solution is preferably 0.05-0.5g / m 2 , and can be specifically 0.05g / m 2 , 0.1g / m 2 , 0.15g / m 2 , 0.2g / m 2 , 0.25g / m 2 , 0.3g / m 2 , 0.35g / m 2 , 0.4g / m 2 , 0.45g / m 2 or 0.5g / m 2 .

[0052] The application can improve the stability and controllability of the interfacial polymerization reaction by optimizing the preparation method of the seawater desalination membrane, especially the solvent of the polyamine monomer solution and the polyacyl chloride monomer solution, and lays a foundation for improving the separation performance of the membrane. On this basis, by immersing the membrane after the interfacial polymerization reaction in a high-temperature treatment liquid containing m-phenylenediamine and sodium pyrosulfite, the performance of the membrane is further improved. Specifically, immersing in the high-temperature treatment liquid containing m-phenylenediamine can cause secondary reaction on the surface of the membrane, thereby avoiding potential structural defects caused by insufficient primary reaction; immersing in the high-temperature treatment liquid containing sodium pyrosulfite can remove chlorine and prevent oxidation, further improving the stability of the membrane. By optimizing the preparation method of the seawater desalination membrane, the application ensures that the nascent membrane after the interfacial polymerization can break through the Trade-off effect to a great extent, so that the membrane has good flux on the basis of maintaining high desalination rate; at the same time, the method effectively avoids potential structural defects on the surface of the membrane, improves the running stability of the membrane, and has good industrial application prospect.

[0053] For a clearer understanding of the application, the following examples and comparative examples are described in detail.

[0054] Example 1

[0055] A preparation method of a seawater desalination membrane, comprising the following steps:

[0056] 1) providing a base membrane;

[0057] In step 1), the front surface of the base membrane is a polysulfone porous support layer (average pore size is 30 nm, thickness is 30 μm), and the back surface is a non-woven fabric layer (thickness is 100 μm);

[0058] 2) coating a polyamine monomer solution on the front surface of the base membrane, and then drying to surface dryness;

[0059] In step 2), the polyamine monomer in the polyamine monomer solution is m-phenylenediamine, and the content of m-phenylenediamine is 3.3 wt%; the solvent of the polyamine monomer solution is imidazole acetate ionic liquid;

[0060] 3) coating a polyacyl chloride monomer solution on the surface-dried front surface of the base membrane to perform interfacial polymerization reaction, and then performing drying treatment to obtain a nascent polyamide separation membrane;

[0061] In step 3), the polyacyl chloride monomer in the polyacyl chloride monomer solution is trimesoyl chloride, and the content of trimesoyl chloride is 0.28 wt%; the solvent of the polyacyl chloride monomer solution is 1-butyl-3-methylimidazolium bistrifluoromethylsulfonylimide salt; the temperature of the drying treatment is 80℃, and the time is 2 min;

[0062] 4) sequentially immersing the nascent polyamide separation membrane in a first treating solution and a second treating solution;

[0063] In step 4), the first treating solution comprises 0.1wt% of m-phenylenediamine, 2wt% of 1-pentyl-3-methylimidazole acetate, and the rest is water; the second treating solution comprises 0.2wt% of sodium metabisulfite, and the rest is water; the temperature of the immersion is 75℃, and the time is 2min;

[0064] 5) sequentially washing the separation membrane treated in step 4) with water and glycerol aqueous solution, then coating polyvinyl alcohol solution on the front side of the separation membrane, drying to obtain a seawater desalination membrane;

[0065] In step 5), the process of washing with water comprises: first rinsing in water at 50℃ for 1min, then rinsing in water at 75℃ for 20min, and finally rinsing in water at 50℃ for 1min;

[0066] In step 5), the glycerol content in the glycerol aqueous solution is 2wt%; the temperature of the immersion in the glycerol aqueous solution is 25℃, and the time is 3min;

[0067] In step 5), the number average molecular weight of the polyvinyl alcohol is 19800~26400, the concentration of the polyvinyl alcohol solution is 2wt%, and the dry coating amount is 0.15g / m 2 .

[0068] Example 2

[0069] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the content of m-phenylenediamine in the polyamine monomer solution is 2.8wt%.

[0070] Example 3

[0071] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the content of m-phenylenediamine in the polyamine monomer solution is 2.7wt%, and the content of trimesoyl chloride in the polyacyl chloride monomer solution is 0.25wt%.

[0072] Example 4

[0073] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the content of m-phenylenediamine in the polyamine monomer solution is 3.4wt%, and the content of trimesoyl chloride in the polyacyl chloride monomer solution is 0.3wt%.

[0074] Comparative Example 1

[0075] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the solvent in the polyamine monomer solution is RO water, and the solvent in the polyacyl chloride monomer solution is Isopar G.

[0076] Comparative Example 2

[0077] A method for preparing a seawater desalination membrane, referring to Example 3, the only difference is that the solvent in the polyamine monomer solution is RO water, and the solvent in the polyacyl chloride monomer solution is Isopar G.

[0078] Comparative Example 3

[0079] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the solvent in the polyacyl chloride monomer solution is Isopar G.

[0080] Comparative Example 4

[0081] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the solvent in the polyamine monomer solution is RO water.

[0082] Comparison of flux and desalination rate of the membrane

[0083] The seawater desalination membranes prepared in Examples 1-4 and Comparative Examples 1-4 were tested for flux and desalination rate, with a 32000mg / L NaCl aqueous solution under a pressure of 800psi, a test liquid temperature of 25±1℃, and a test liquid pH of 7.0±0.5. The preparation conditions of Examples 1-4 and Comparative Examples 1-4 and the flux and desalination rate test results are summarized in Table 1:

[0084] Table 1 Flux and desalination rate test results of Examples 1-4 and Comparative Examples 1-4

[0085]

[0086] As can be seen from Table 1, the desalination rate and flux of the examples can be maintained at a high level, which is significantly better than the comparative examples.

[0087] Comparative Example 5

[0088] A method for preparing a seawater desalination membrane, referring to Example 1, the only difference is that the nascent polyamide separation membrane is not treated in step 4).

[0089] Stability test

[0090] The seawater desalination membrane prepared in Example 1 and Comparative Example 5 was subjected to a running stability test, using a 32000 mg / L NaCl aqueous solution at a pressure of 800 psi, a test liquid temperature of 25±1℃, a test liquid pH of 7.0±0.5, and the water production was tested every twenty minutes for 2 hours. The results are shown in Table 2.

[0091] Table 2. Results of running stability test

[0092]

[0093] As can be seen from Table 2, the desalination stability of the membrane sheet of Example 1 is significantly improved compared to Comparative Example 5. This shows that by immersing the membrane sheet after the completion of the interfacial polymerization reaction in a high-temperature treatment liquid containing m-phenylenediamine, the running stability of the membrane sheet can be improved.

[0094] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing a seawater desalination membrane, characterized by, The method comprises the following steps: a) providing a base film; In step a), the front side of the base film is a porous support layer, and the back side is a non-woven fabric layer; b) coating a polyamine monomer solution on the front side of the base film, and then drying to a tack-free state of the base film; In step b), the solvent of the polyamine monomer solution is imidazole acetate ionic liquid; c) coating a polyacyl chloride monomer solution on the front side of the tack-free base film to perform interfacial polymerization, and then performing drying treatment to obtain a nascent polyamide separation membrane; In step c), the solvent of the polyacyl chloride monomer solution is one or more of 1-ethyl-3-methylimidazole tetrafluoroborate, 1-ethyl-3-methylimidazole dicyanamide, 1-butyl-3-methylimidazole tetrafluoroborate, 1-butyl-3-methylimidazole hexafluorophosphate, 1-butyl-3-methylimidazole bistrifluoromethylsulfonylimide, and 1-butyl-3-methylimidazole trifluoromethanesulfonate; d) sequentially immersing the nascent polyamide separation membrane in a first treatment liquid and a second treatment liquid; In step d), the components of the first treatment liquid include m-phenylenediamine and 1-pentyl-3-methylimidazole acetate; the components of the second treatment liquid include sodium metabisulfite; the immersion temperature in the first treatment liquid and the second treatment liquid is 60-80℃; e) sequentially performing water washing and glycerol aqueous solution immersion on the separation membrane treated in step d), and then coating a polyvinyl alcohol solution on the front side of the separation membrane and drying to obtain a seawater desalination membrane.

2. The production method according to claim 1, characterized by, In step b), the polyamine monomer in the polyamine monomer solution is m-phenylenediamine; the content of the polyamine monomer in the polyamine monomer solution is 1-4wt%.

3. The preparation method according to claim 1, characterized in that, In step b), the imidazole acetate ionic liquid is 1-pentyl-3-methylimidazole acetate.

4. The method of claim 1, wherein, In step c), the polyacyl chloride monomer in the polyacyl chloride monomer solution is trimesoyl chloride and / or adipoyl chloride; the content of the polyacyl chloride monomer in the polyacyl chloride monomer solution is 0.2-0.4wt%.

5. The preparation method according to claim 1, characterized in that, In step c), the drying treatment temperature is 60-100℃; the drying treatment time is 1-3min.

6. The method of claim 1, wherein, In step d), the content of m-phenylenediamine in the first treatment liquid is 0.1-0.5wt%; the content of 1-pentyl-3-methylimidazole acetate in the first treatment liquid is 1-5wt%; the content of sodium metabisulfite in the second treatment liquid is 0.1-0.5wt%.

7. The preparation method according to claim 1, characterized in that, In step d), the immersion time in the first treatment liquid and the second treatment liquid is 1-2min.

8. The method of claim 1, wherein, In step e), the water washing process comprises: firstly performing first rinsing in water at 40-60℃, then performing second rinsing in water at 70-80℃, and finally performing third rinsing in water at 40-60℃.

9. The production method according to claim 8, characterized by, The first rinsing time is 0.5-1min; the second rinsing time is 15-20min; and the third rinsing time is 0.5-1min.

10. The method of claim 1, wherein, In step e), the glycerol content in the glycerol aqueous solution is 1-5 wt%; the temperature of the glycerol aqueous solution soaking is 10-40℃; and the time of the glycerol aqueous solution soaking is 2-3 min. In step e), the glycerol content in the glycerol aqueous solution is 1-5 wt%; the temperature of the glycerol aqueous solution soaking is 10-40℃; and the time of the glycerol aqueous solution soaking is 2-3 min. In step e),

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