Reverse osmosis membrane as well as preparation method and application thereof

Abstract

The invention relates to a reverse osmosis membrane as well as a preparation method and application thereof, and the preparation method of the reverse osmosis membrane comprises the following steps: preparing a cationic surfactant, sodium cyclamate and water into a mixed solution; the mixed solution, an oil solution containing multi-element acyl chloride and a polyvinyl alcohol aqueous solution are sequentially placed on the same surface of a supporting membrane to form organic nanoparticles, the mass ratio of the sodium cyclohexylamino sulfonate to the multi-element acyl chloride is 5: 1-10: 1, and the mass ratio of the polyvinyl alcohol to the multi-element acyl chloride is 1: 1-5: 1; and preparing a polyamide separation layer on the surface of the support membrane on which the organic nanoparticles are distributed through interfacial polymerization to obtain the reverse osmosis membrane. When the reverse osmosis membrane prepared by the preparation method is applied to water treatment, high salt interception performance can be maintained, and meanwhile, high water flux and high pollution resistance are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment membranes, and particularly to a reverse osmosis membrane, a preparation method thereof, and an application thereof. Background Art

[0002] Reverse osmosis is an energy-efficient water treatment method and has been widely used in seawater desalination, drinking water treatment, water reuse, etc. However, existing reverse osmosis membranes still have the problem that they cannot have both high water flux and high anti-fouling performance. Summary of the Invention

[0003] Based on this, in view of the above problems, it is necessary to provide a reverse osmosis membrane, a preparation method thereof, and an application thereof. When the reverse osmosis membrane prepared by this preparation method is applied to water treatment, it can maintain high salt rejection performance while having both high water flux and high anti-fouling performance.

[0004] A preparation method of a reverse osmosis membrane includes the following steps:

[0005] Prepare a mixed solution by mixing a cationic surfactant, sodium cyclohexylsulfamate, and water;

[0006] Place the mixed solution, an oil solution containing polyfunctional acyl chloride, and an aqueous solution of polyvinyl alcohol on the same surface of a support membrane in sequence to form organic nanoparticles, wherein the mass ratio of sodium cyclohexylsulfamate to polyfunctional acyl chloride is 5:1 - 10:1, and the mass ratio of polyvinyl alcohol to polyfunctional acyl chloride is 1:1 - 5:1;

[0007] Prepare a polyamide separation layer on the surface of the support membrane on which the organic nanoparticles are distributed by interfacial polymerization to obtain a reverse osmosis membrane.

[0008] In one embodiment, the mass fraction of the cationic surfactant in the mixed solution is 0.01% - 0.1%.

[0009] In one embodiment, the mass fraction of sodium cyclohexylsulfamate in the mixed solution is 0.5% - 5%.

[0010] In one embodiment, the mass fraction of polyfunctional acyl chloride in the oil solution containing polyfunctional acyl chloride is 0.1% - 0.5%.

[0011] In one embodiment, the mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 0.1% - 2.5%.

[0012] In one embodiment, the cationic surfactant is selected from at least one of dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride;

[0013] And / or, the polyfunctional acyl chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

[0014] In one embodiment, in the step of sequentially placing the mixed solution, the oil solution containing polyfunctional acyl chloride, and the aqueous solution of polyvinyl alcohol on the same surface of the support membrane to form organic nanoparticles, the mixed solution, the oil solution containing polyfunctional acyl chloride, and the aqueous solution of polyvinyl alcohol are sequentially placed on the same surface of the support membrane, and organic nanoparticles are formed by heat treatment. Among them, the temperature of the heat treatment is 50°C - 60°C, and the time of the heat treatment is 3 min - 5 min.

[0015] In one embodiment, in the step of preparing a polyamide separation layer on the surface of the support membrane distributed with organic nanoparticles by interfacial polymerization, an aqueous phase solution and an oil phase solution are sequentially placed on the surface of the support membrane distributed with organic nanoparticles, and then a polyamide separation layer is formed by heat treatment. Among them, the aqueous phase solution includes polyamine, and the oil phase solution includes polyfunctional acyl chloride.

[0016] A reverse osmosis membrane prepared by using the preparation method of the reverse osmosis membrane described above.

[0017] An application of the reverse osmosis membrane described above in a water treatment device.

[0018] In the preparation method of the reverse osmosis membrane of the present invention, when a mixed solution prepared from a cationic surfactant, sodium cyclamate, and water, an oil solution containing polyfunctional acyl chloride, and an aqueous solution of polyvinyl alcohol are sequentially placed on the same surface of the support membrane, sodium cyclamate is evenly distributed at the water-oil interface under the electrostatic action of the cationic surfactant. By controlling the mass ratio of sodium cyclamate, polyvinyl alcohol, and polyfunctional acyl chloride, sodium cyclamate only undergoes an interfacial polymerization reaction with some of the acyl chloride groups in the polyfunctional acyl chloride, while polyvinyl alcohol continues to undergo an interfacial polymerization reaction with the remaining acyl chloride groups of the polyfunctional acyl chloride to form organic nanoparticles with a relatively low crosslinking degree and evenly distributed on the surface of the support membrane. On the one hand, the organic nanoparticles can effectively avoid the problem that the excessive crosslinking degree of polyvinyl alcohol and acyl chloride groups affects the water flux of the reverse osmosis membrane, and at the same time can correspondingly increase the water production channels to further improve the water flux of the reverse osmosis membrane. On the other hand, they contain a large number of unreacted hydroxyl groups, greatly increasing the hydrophilicity of the organic nanoparticles themselves, effectively improving the anti-pollution performance of the reverse osmosis membrane, and at the same time enabling the organic nanoparticles to have good compatibility with the subsequently prepared polyamide separation layer and improving their firmness in the reverse osmosis membrane.

[0019] Therefore, when the reverse osmosis membrane of the present invention is applied to water treatment, it can maintain high salt rejection performance while having high water flux and high anti-pollution performance. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 It is the electron microscope image of the reverse osmosis membrane prepared in Example 1 of the present invention;

[0022] Figure 2 It is the electron microscope image of the reverse osmosis membrane prepared in Comparative Example 8 of the present invention. Specific embodiments

[0023] For the convenience of understanding the present invention, the following will describe the present invention in more detail. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure content of the present invention more thorough and comprehensive.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments or examples and are not intended to limit the present invention. The optional range of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items. The any and all combinations include any two related listed items, any more related listed items, or the combination of all related listed items.

[0025] The preparation method of the reverse osmosis membrane provided by the present invention includes the following steps:

[0026] Prepare a mixed solution by mixing a cationic surfactant, sodium cyclohexylsulfamate, and water;

[0027] Place the mixed solution, an oil solution containing polyfunctional acyl chloride, and an aqueous solution of polyvinyl alcohol on the same surface of the support membrane in sequence to form organic nanoparticles, wherein the mass ratio of sodium cyclohexylsulfamate to polyfunctional acyl chloride is 5:1 - 10:1, and the mass ratio of polyvinyl alcohol to polyfunctional acyl chloride is 1:1 - 5:1;

[0028] Prepare a polyamide separation layer on the surface of the support membrane distributed with organic nanoparticles through interfacial polymerization to obtain a reverse osmosis membrane.

[0029] In the present invention, when the mixed solution and the oil solution containing polyvalent acyl chloride are sequentially placed on the same surface of the support membrane, a water-oil interface is formed when the mixed solution contacts the oil solution containing polyvalent acyl chloride. The cationic surfactant in the mixed solution will be uniformly distributed at the water-oil interface, and sodium cyclohexylsulfamate and the cationic surfactant will attract each other due to electrostatic interaction. Therefore, under the electrostatic action of the cationic surfactant, sodium cyclohexylsulfamate will also be uniformly distributed at the water-oil interface. At the same time, sodium cyclohexylsulfamate will undergo an interfacial polymerization reaction with polyvalent acyl chloride. In this process, by controlling the mass ratio of sodium cyclohexylsulfamate to the polyvalent acyl chloride, sodium cyclohexylsulfamate will only undergo an interfacial polymerization reaction with some of the acyl chloride groups of the polyvalent acyl chloride. Therefore, there will be some unreacted acyl chloride groups remaining in the polyvalent acyl chloride. Moreover, since sodium cyclohexylsulfamate is uniformly distributed at the water-oil interface, in this process, the polyvalent acyl chloride reacting with sodium cyclohexylsulfamate will also be uniformly distributed at the water-oil interface.

[0030] When the aqueous solution of polyvinyl alcohol is placed on the same surface of the support membrane, polyvinyl alcohol will continue to undergo an interfacial polymerization reaction with the remaining acyl chloride groups of polyvalent acyl chloride to form organic nanoparticles. In this process, by controlling the mass ratio of polyvinyl alcohol to polyvalent acyl chloride, the crosslinking degree of the two can be effectively controlled, so that the formed organic nanoparticles have a low crosslinking degree. At the same time, since the polyvalent acyl chloride is uniformly distributed at the water-oil interface, the formed organic nanoparticles are uniformly distributed on the surface of the support membrane. On the one hand, the organic nanoparticles can effectively avoid the problem that the excessive crosslinking degree of polyvinyl alcohol and acyl chloride groups affects the water flux of the reverse osmosis membrane. At the same time, the presence of the organic nanoparticles can also correspondingly increase the water production channels and further improve the water flux of the reverse osmosis membrane. On the other hand, the organic nanoparticles contain a large number of unreacted hydroxyl groups, which greatly increases the hydrophilicity of the organic nanoparticles themselves, can effectively improve the anti-fouling performance of the reverse osmosis membrane, and can also make the organic nanoparticles have good compatibility with the subsequently prepared polyamide separation layer and improve their firmness in the reverse osmosis membrane.

[0031] In addition, by preparing a polyamide separation layer on the surface of the support membrane where the organic nanoparticles are distributed through interfacial polymerization, it can effectively ensure that the reverse osmosis membrane has high salt rejection performance, and at the same time make the organic nanoparticles tightly and firmly distributed between the support membrane and the polyamide separation layer, which can effectively prevent the organic nanoparticles from falling off during use.

[0032] Therefore, when the reverse osmosis membrane of the present invention is applied to water treatment, it can maintain high salt rejection performance while having high water flux and high anti-fouling performance.

[0033] It should be noted that for the sodium cyclamate in the mixed solution of the present invention, on the one hand, it can first react with some acyl chloride groups of the polyvalent acyl chloride, consuming some acyl chloride groups, so that the cross-linking degree of the organic nanoparticles formed by the reaction of polyvinyl alcohol and polyvalent acyl chloride is relatively low, which can effectively reduce the resistance of the reverse osmosis membrane to water, improve the water flux of the reverse osmosis membrane, and enable a large number of unreacted hydroxyl groups to be contained on the organic nanoparticles, having high hydrophilicity. While improving the anti-fouling performance of the reverse osmosis membrane, it can also improve its compatibility with the polyamide separation layer and prevent it from falling off from the reverse osmosis membrane; on the other hand, under the action of the cationic surfactant, sodium cyclamate is evenly distributed at the water-oil interface, which can also make the polyvalent acyl chloride reacting with it evenly distributed at the water-oil interface, and then make the organic nanoparticles formed by the reaction of polyvinyl alcohol and polyvalent acyl chloride evenly distributed on the surface of the support membrane, which can increase the water production channels and further improve the water flux of the reverse osmosis membrane.

[0034] Optionally, the mass fraction of the cationic surfactant in the mixed solution is 0.01% - 0.1%. With such a setting, by adjusting the dosage of the cationic surfactant, sodium cyclamate can be more evenly distributed at the water-oil interface and react with polyvalent acyl chloride, which is conducive to the more uniform distribution of the organic nanoparticles formed by the reaction of polyvalent acyl chloride and polyvinyl alcohol on the surface of the support membrane, further improving the water flux and anti-fouling performance of the reverse osmosis membrane.

[0035] Further, the cationic surfactant is selected from at least one of dodecyl trimethyl ammonium bromide and dodecyl trimethyl ammonium chloride.

[0036] Optionally, the mass fraction of sodium cyclamate in the mixed solution is 0.5% - 5%; the mass fraction of the polyvalent acyl chloride in the oil solution containing polyvalent acyl chloride is 0.1% - 0.5%; the mass fraction of polyvinyl alcohol in the aqueous polyvinyl alcohol solution is 0.1% - 2.5%. With such a setting, by adjusting the mass fraction of sodium cyclamate in the mixed solution, the mass fraction of the polyvalent acyl chloride in the oil solution containing polyvalent acyl chloride, and the mass fraction of polyvinyl alcohol in the aqueous polyvinyl alcohol solution, the mass ratio of sodium cyclamate to the polyvalent acyl chloride and the mass ratio of polyvinyl alcohol to the polyvalent acyl chloride can be better controlled, and then organic nanoparticles with low cross-linking degree and uniform distribution can be better formed, and the water flux and anti-fouling performance of the reverse osmosis membrane can be better improved.

[0037] Further, the polyacid chloride is selected from at least one of trimellitic acid chloride, isophthaloyl chloride, and terephthaloyl chloride, and preferably trimellitic acid chloride. With such a setting, the amino group of sodium cyclohexylsulfamate first reacts with one acid chloride group in trimellitic acid chloride, leaving two acid chloride groups in trimellitic acid chloride. The remaining two acid chloride groups of trimellitic acid chloride can polymerize with polyvinyl alcohol at the water-oil interface through interfacial polymerization to form organic nanoparticles with a relatively low degree of crosslinking.

[0038] It can be understood that the oil solution containing polyacid chloride in the present invention is obtained by mixing polyacid chloride and an organic solvent. Among them, the organic solvent is preferably an isoparaffin solvent, and the isoparaffin solvent is selected from at least one of Isopar-E, Isopar-G, and Isopar-L.

[0039] Optionally, in the step of sequentially placing the mixed solution, the oil solution containing polyacid chloride, and the aqueous solution of polyvinyl alcohol on the same surface of the support membrane to form organic nanoparticles, the mixed solution, the oil solution containing polyacid chloride, and the aqueous solution of polyvinyl alcohol are sequentially placed on the same surface of the support membrane and heat-treated to form organic nanoparticles. Among them, the temperature of the heat treatment is 50°C - 60°C, and the time of the heat treatment is 3 min - 5 min. With such a setting, it is beneficial to enable the remaining groups of polyvinyl alcohol and polyacid chloride to react sufficiently to obtain organic nanoparticles with a relatively low degree of crosslinking and uniform distribution.

[0040] Optionally, in the step of preparing a polyamide separation layer on the surface of the support membrane on which organic nanoparticles are distributed through interfacial polymerization, an aqueous solution and an oil solution are sequentially placed on the surface of the support membrane on which organic nanoparticles are distributed, and then heat-treated to form a polyamide separation layer. Among them, the aqueous solution includes polyamine, and the oil solution includes polyacid chloride. It can be understood that polyamine and polyacid chloride form a polyamide separation layer through an interfacial polymerization reaction to ensure that the reverse osmosis membrane has high salt rejection performance.

[0041] In one embodiment, the mass fraction of polyamine in the aqueous solution is 1% - 3%, and the mass fraction of polyacid chloride in the oil solution is 0.1% - 0.5%. With such a setting, it is beneficial to enable sufficient reaction between polyamine and polyacid chloride to form a relatively dense polyamide separation layer, which is beneficial for the reverse osmosis membrane to maintain high salt rejection performance.

[0042] Further, the polyamine is selected from at least one of m-phenylenediamine, piperazine, p-phenylenediamine, and tetraethylenepentamine, and preferably m-phenylenediamine; the polyacid chloride is selected from at least one of trimellitic acid chloride, isophthaloyl chloride, and terephthaloyl chloride, and preferably trimellitic acid chloride.

[0043] In order to better remove the hydrochloric acid generated by the interfacial polymerization reaction to ensure the forward progress of the polymerization reaction between polyamine and polyacyl chloride, in the present invention, the aqueous solution further includes an acid absorbent, and the mass fraction of the acid absorbent in the aqueous solution is 0.5% - 3%.

[0044] Furthermore, the acid absorbent is selected from at least one of triethylamine, sodium hydroxide, potassium hydroxide, sodium carbonate, trisodium phosphate, disodium hydrogen phosphate, sodium dihydrogen phosphate, potassium phosphate, dipotassium hydrogen phosphate, and preferably triethylamine.

[0045] In one embodiment, in the step of forming the polyamide separation layer by heat treatment, the temperature of the heat treatment is 75°C - 100°C, and the time of the heat treatment is 2 min - 4 min. With such settings, the integrity and uniformity of the crosslinking of the polyamide separation layer can be further ensured, and the salt rejection performance and water flux of the reverse osmosis membrane can be further improved.

[0046] In one embodiment, the solvent of the oil phase solution is selected from isoparaffin solvents, and the isoparaffin solvents are selected from at least one of Isopar - E, Isopar - G, and Isopar - L; the solvent of the aqueous solution is water.

[0047] In one embodiment, the support membrane is selected from at least one of polysulfone membranes, polypropylene membranes, or polyacrylonitrile membranes. Among them, polysulfone is inexpensive and easily available, the membrane preparation is simple, it has good mechanical strength, good compressive resistance performance, stable chemical properties, is non - toxic, and can resist biodegradation. Therefore, the support membrane is preferably a polysulfone membrane.

[0048] Meanwhile, the present invention also provides a reverse osmosis membrane prepared by using the preparation method of the reverse osmosis membrane described above. When this reverse osmosis membrane is applied to water treatment, it can maintain high salt rejection performance while having high water flux and high anti - fouling performance.

[0049] In addition, the present invention also provides an application of the reverse osmosis membrane described above in a water treatment device.

[0050] In one embodiment, the water treatment device can be a purifier. When the reverse osmosis membrane is applied to a water purifier, during the water purification process, the raw water to be purified enters from the separation layer of the reverse osmosis membrane, and the raw water forms pure water by passing through the reverse osmosis membrane under the action of pressure.

[0051] In one embodiment, the water treatment device can also be a seawater desalination device.

[0052] Hereinafter, the reverse osmosis membrane, its preparation method and application will be further described by the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention. For those not specified in the examples, they are carried out under conventional conditions or conditions recommended by the manufacturer. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through commercial purchase.

[0053] Example 1

[0054] Dodecyltrimethylammonium bromide, sodium cyclamate and water were mixed evenly to prepare a mixed solution. Among them, in the mixed solution, the mass fraction of dodecyltrimethylammonium bromide was 0.1%, and the mass fraction of sodium cyclamate was 5%; Trimellitic acid chloride and isoparaffin solvent (Isopar-L) were mixed evenly to prepare an oil solution containing trimellitic acid chloride. Among them, in the oil solution containing trimellitic acid chloride, the mass fraction of trimellitic acid chloride was 0.5%; m-Phenylenediamine, triethylamine and water were mixed evenly to prepare an aqueous solution. Among them, in the aqueous solution, the mass fraction of m-phenylenediamine was 3%, and the mass fraction of triethylamine was 3%; Trimellitic acid chloride and isoparaffin solvent (Isopar-L) were mixed evenly to prepare an oil phase solution. Among them, in the oil phase solution, the mass fraction of trimellitic acid chloride was 0.4%.

[0055] The above mixed solution was coated on the surface of the polysulfone support membrane. After there were no obvious liquid beads on the surface, the oil solution containing trimellitic acid chloride was coated. After standing for 30 s, the excess oil solution was poured out, and the polysulfone support membrane was air-dried; Then the aqueous solution of polyvinyl alcohol was coated, and then the excess aqueous solution of polyvinyl alcohol was poured out, and the polysulfone support membrane was air-dried to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane. Among them, in the aqueous solution of polyvinyl alcohol, the mass fraction of polyvinyl alcohol was 2%, the mass ratio of sodium cyclamate to trimellitic acid chloride was 10:1, and the mass ratio of polyvinyl alcohol to trimellitic acid chloride was 4:1.

[0056] The above aqueous solution was coated on the surface of the polysulfone support membrane distributed with organic nanoparticles. After standing for 60 s, the excess aqueous solution was poured out, and the membrane surface was dried with cold air. Then the above oil phase solution was coated on the same surface of the polysulfone support membrane. After standing for 30 s, the excess oil phase solution was poured out. After draining, it was placed in an 80 °C oven for 3 min to obtain the Figure 1 reverse osmosis membrane as shown.

[0057] Example 2

[0058] Mix dodecyl trimethyl ammonium bromide, sodium cyclamate and water evenly to prepare a mixed solution. Among them, in the mixed solution, the mass fraction of dodecyl trimethyl ammonium bromide is 0.05%, and the mass fraction of sodium cyclamate is 2.1%; Mix trimellitic acid chloride and isoparaffin solvent (Isopar-L) evenly to prepare an oil solution containing trimellitic acid chloride. Among them, in the oil solution containing trimellitic acid chloride, the mass fraction of trimellitic acid chloride is 0.3%; Mix m-phenylenediamine, triethylamine and water evenly to prepare an aqueous solution. Among them, in the aqueous solution, the mass fraction of m-phenylenediamine is 2%, and the mass fraction of triethylamine is 2%; Mix trimellitic acid chloride and isoparaffin solvent (Isopar-L) evenly to prepare an oil phase solution. Among them, in the oil phase solution, the mass fraction of trimellitic acid chloride is 0.3%.

[0059] Coat the above mixed solution on the surface of the polysulfone support membrane. After there are no obvious liquid beads on the surface, coat the oil solution containing trimellitic acid chloride. After standing for 30 s, pour out the excess oil solution, and air-dry the polysulfone support membrane; Then coat the polyvinyl alcohol aqueous solution, and then pour out the excess polyvinyl alcohol aqueous solution, and air-dry the polysulfone support membrane to obtain organic nanoparticles evenly distributed on the surface of the polysulfone support membrane. Among them, in the polyvinyl alcohol aqueous solution, the mass fraction of polyvinyl alcohol is 0.9%, the mass ratio of sodium cyclamate to trimellitic acid chloride is 7:1, and the mass ratio of polyvinyl alcohol to trimellitic acid chloride is 3:1.

[0060] Coat the above aqueous solution on the surface of the polysulfone support membrane distributed with organic nanoparticles. After standing for 60 s, pour out the excess aqueous solution, and dry the membrane surface with cold air. Then coat the above oil phase solution on the same surface of the polysulfone support membrane. After standing for 30 s, pour out the excess oil phase solution. After draining, put it into an oven at 90 °C for 2 min to obtain a reverse osmosis membrane.

[0061] Example 3

[0062] Mix dodecyl trimethyl ammonium bromide, sodium cyclamate and water evenly to prepare a mixed solution. Among them, in the mixed solution, the mass fraction of dodecyl trimethyl ammonium bromide is 0.01%, and the mass fraction of sodium cyclamate is 0.5%; Mix trimellitic acid chloride and isoparaffin solvent (Isopar-L) evenly to prepare an oil solution containing trimellitic acid chloride. Among them, in the oil solution containing trimellitic acid chloride, the mass fraction of trimellitic acid chloride is 0.1%; Mix m-phenylenediamine, triethylamine and water evenly to prepare an aqueous solution. Among them, in the aqueous solution, the mass fraction of m-phenylenediamine is 1%, and the mass fraction of triethylamine is 2%; Mix trimellitic acid chloride and isoparaffin solvent (Isopar-L) evenly to prepare an oil phase solution. Among them, in the oil phase solution, the mass fraction of trimellitic acid chloride is 0.1%.

[0063] Apply the above mixed solution to the surface of the polysulfone support membrane. After there are no obvious liquid beads on the surface, apply the oil solution containing trimesoyl chloride. After standing for 30 s, pour out the excess oil solution, and air-dry the polysulfone support membrane; then apply the aqueous solution of polyvinyl alcohol, and then pour out the excess aqueous solution of polyvinyl alcohol, and air-dry the polysulfone support membrane to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane. Among them, the mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 0.1%, the mass ratio of sodium cyclamate to trimesoyl chloride is 5:1, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 1:1.

[0064] Apply the above aqueous solution to the surface of the polysulfone support membrane distributed with organic nanoparticles. After standing for 60 s, pour out the excess aqueous solution, and dry the membrane surface with cold air. Then apply the above oil phase solution to the same surface of the polysulfone support membrane. After standing for 30 s, pour out the excess oil phase solution. After draining, place it in an oven at 85 °C for 3 min to obtain a reverse osmosis membrane.

[0065] Example 4

[0066] Compared with Example 1, Example 4 is only different in that the mass fraction of dodecyl trimethyl ammonium bromide in the mixed solution is 0.005%, and the other conditions are the same, and a reverse osmosis membrane is obtained.

[0067] Example 5

[0068] Compared with Example 1, Example 5 is only different in that the mass fraction of dodecyl trimethyl ammonium bromide in the mixed solution is 0.2%, and the other conditions are the same, and a reverse osmosis membrane is obtained.

[0069] Example 6

[0070] Compared with Example 1, Example 6 is only different in that the mass fraction of sodium cyclamate in the mixed solution is 0.3%, and the other conditions are the same, and a reverse osmosis membrane is obtained.

[0071] Example 7

[0072] Compared with Example 1, Example 7 is only different in that the mass fraction of sodium cyclamate in the mixed solution is 6%, and the other conditions are the same, and a reverse osmosis membrane is obtained.

[0073] Example 8

[0074] Compared with Example 1, Example 8 is only different in that the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.05%, and the other conditions are the same, and a reverse osmosis membrane is obtained.

[0075] Example 9

[0076] Example 9 is different from Example 1 only in that the mass fraction of trimellitic acid chloride in the oil solution containing trimellitic acid chloride is 0.6%, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0077] Example 10

[0078] Example 10 is different from Example 1 only in that the mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 0.05%, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0079] Example 11

[0080] Example 11 is different from Example 1 only in that the mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 3%, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0081] Example 12

[0082] Example 12 is different from Example 1 only in that in the mixed solution, dodecyl trimethyl ammonium chloride is used instead of dodecyl trimethyl ammonium bromide, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0083] Example 13

[0084] Example 13 is different from Example 1 only in that isophthaloyl chloride is used instead of trimellitic acid chloride, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0085] Example 14

[0086] Example 14 is different from Example 1 only in that then an aqueous solution of polyvinyl alcohol is further coated, and then the excess aqueous solution of polyvinyl alcohol is poured out. After the polysulfone support membrane is air-dried, it is placed in an oven at 60 °C for 3 min to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0087] Comparative Example 1

[0088] Comparative Example 1 is different from Example 1 only in that cyclohexylsulfamic acid sodium is not contained in the mixed solution, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0089] Comparative Example 2

[0090] Comparative Example 2 is different from Example 1 only in that dodecyl trimethyl ammonium bromide is not contained in the mixed solution, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0091] Comparative Example 3

[0092] Comparative Example 3 is different from Example 1 only in that the aqueous solution of polyvinyl alcohol is not contained, and the other conditions are the same, obtaining a reverse osmosis membrane.

[0093] Comparative Example 4

[0094] Comparative Example 4 is different from Example 1 only in that the mass fraction of sodium cyclamate in the mixed solution is 5%, the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.1%, and the mass ratio of sodium cyclamate to trimesoyl chloride is 50:1, and the rest of the conditions are the same, obtaining a reverse osmosis membrane.

[0095] Comparative Example 5

[0096] Comparative Example 5 is different from Example 1 only in that the mass fraction of sodium cyclamate in the mixed solution is 6%, the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.6%, and the mass ratio of sodium cyclamate to trimesoyl chloride is 1:1, and the rest of the conditions are the same, obtaining a reverse osmosis membrane.

[0097] Comparative Example 6

[0098] Comparative Example 6 is different from Example 1 only in that the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.3%, the mass fraction of polyvinyl alcohol in the aqueous polyvinyl alcohol solution is 0.15%, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 1:2, and the rest of the conditions are the same, obtaining a reverse osmosis membrane.

[0099] Comparative Example 7

[0100] Comparative Example 7 is different from Example 1 only in that the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.4%, the mass fraction of polyvinyl alcohol in the aqueous polyvinyl alcohol solution is 6%, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 15:1, and the rest of the conditions are the same, obtaining a reverse osmosis membrane.

[0101] Comparative Example 8

[0102] Comparative Example 8 is different from Example 1 only in that an aqueous glutaraldehyde solution is used to replace the oil solution containing trimesoyl chloride. Among them, the mass fraction of glutaraldehyde in the aqueous glutaraldehyde solution is 0.05%, the mass ratio of sodium cyclamate to glutaraldehyde is 5:1, and the mass ratio of polyvinyl alcohol to glutaraldehyde is 5:1, and the rest of the conditions are the same, obtaining a reverse osmosis membrane as Figure 2 shown.

[0103] Performance tests were carried out on the reverse osmosis membranes prepared in Examples 1 to 14 and Comparative Examples 1 to 8. The test conditions were: the test pressure was 1.55 MPa, the concentrated water flow rate was 1.0 GPM, the ambient temperature was 25 °C, the pH value of the concentrated water was 6.5 - 7.5, the concentrated water was a 2000 PPm sodium chloride aqueous solution, and the test results are shown in Table 1.

[0104] Table 1

[0105]

[0106] Meanwhile, the anti-fouling performance of the reverse osmosis membranes prepared in Examples 1 to 14 and Comparative Examples 1 to 8 was tested under the following conditions: the test pressure was 1.55 MPa, the concentrated water flow rate was 1.0 GPM, the ambient temperature was 25 °C, the pH value of the concentrated water was 6.5 - 7.5, and the anti-fouling performance test was carried out with the concentrated water of 2000 ppm sodium chloride + 100 ppm sodium humate + 100 ppm bovine serum albumin as the feed water. After continuous operation for 100 h, the membrane was cleaned, and then the performance test was carried out with the concentrated water of 2000 ppm sodium chloride as the feed water. The test results are shown in Table 2.

[0107] Table 2

[0108]

[0109] It should be noted that in Tables 1 to 2, the membrane water flux (F) is calculated by the volume of water passing through the reverse osmosis membrane in a certain time, and the formula is: F = V / (A × T), where V is the volume of water passing through the reverse osmosis membrane per unit time, A is the effective membrane area, and T is the time.

[0110] The rejection rate (R) is calculated by the concentration of the feed liquid and the concentration of the permeate liquid, and the calculation formula is: R = (1 - C1 / C0) × 100%, where C1 is the concentration of the permeate liquid and C0 is the concentration of the feed liquid.

[0111] The calculation formula of the water flux recovery rate is: (the water flux of the reverse osmosis membrane after fouling / the water flux of the initial reverse osmosis membrane) × 100%.

[0112] From Figure 1 it can be seen that the surface of the reverse osmosis membrane prepared in Example 1 has larger flat blades, indicating that the cross-linking degree of the organic nanoparticles is low and evenly distributed, which can make the reverse osmosis membrane have a relatively loose structure, conducive to increasing the specific surface area of the reverse osmosis membrane and improving the water flux.

[0113] From Figure 2 it can be seen that in Comparative Example 8, an aqueous glutaraldehyde solution was used to replace the oil solution containing trimellitic acid chloride, resulting in a high cross-linking density of the formed organic nanoparticles, an increase in the number of particles on the surface of the prepared reverse osmosis membrane, and fewer leaf-like morphologies, thereby affecting the water flux of the reverse osmosis membrane.

[0114] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0115] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing a reverse osmosis membrane, characterized in that, It includes the following steps: Prepare a mixed solution by mixing a cationic surfactant, sodium cyclamate, and water; Place the mixed solution, an oil solution containing polyacyl chloride, and an aqueous solution of polyvinyl alcohol in sequence on the same surface of a support membrane to form organic nanoparticles, wherein the mass ratio of sodium cyclamate to polyacyl chloride is 5:1 - 10:1, and the mass ratio of polyvinyl alcohol to polyacyl chloride is 1:1 - 5:1; Prepare a polyamide separation layer on the surface of the support membrane distributed with organic nanoparticles through interfacial polymerization to obtain a reverse osmosis membrane.

2. The method for preparing a reverse osmosis membrane according to claim 1, characterized in that, The mass fraction of the cationic surfactant in the mixed solution is 0.01% - 0.1%.

3. The preparation method of the reverse osmosis membrane according to claim 1, wherein, The mass fraction of sodium cyclamate in the mixed solution is 0.5% - 5%.

4. The preparation method of the reverse osmosis membrane according to claim 1, characterized in that, The mass fraction of polyacyl chloride in the oil solution containing polyacyl chloride is 0.1% - 0.5%.

5. The preparation method of the reverse osmosis membrane according to claim 1, wherein The mass fraction of polyvinyl alcohol in the aqueous solution of polyvinyl alcohol is 0.1% - 2.5%.

6. The preparation method of the reverse osmosis membrane according to claim 1, wherein, The cationic surfactant is selected from at least one of dodecyl trimethyl ammonium bromide and dodecyl trimethyl ammonium chloride; And / or, the polyacyl chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride.

7. The preparation method of the reverse osmosis membrane according to claim 1, characterized in that, In the step of placing the mixed solution, an oil solution containing polyacyl chloride, and an aqueous solution of polyvinyl alcohol in sequence on the same surface of a support membrane to form organic nanoparticles, the mixed solution, the oil solution containing polyacyl chloride, and the aqueous solution of polyvinyl alcohol are placed in sequence on the same surface of the support membrane and heat-treated to form organic nanoparticles, wherein the temperature of the heat treatment is 50°C - 60°C, and the time of the heat treatment is 3 min - 5 min.

8. The method for preparing a reverse osmosis membrane according to any one of claims 1 to 7, characterized in that, In the step of preparing a polyamide separation layer on the surface of the support membrane distributed with organic nanoparticles through interfacial polymerization, an aqueous solution and an oil solution are placed in sequence on the surface of the support membrane distributed with organic nanoparticles, and then heat-treated to form a polyamide separation layer, wherein the aqueous solution includes polyamine, and the oil solution includes polyacyl chloride.

9. A reverse osmosis membrane prepared by using the preparation method of the reverse osmosis membrane according to any one of claims 1 to 8.

10. An application of the reverse osmosis membrane according to claim 9 in a water treatment device.

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