Reverse osmosis membrane and its preparation method and application

Abstract

The present invention relates to a reverse osmosis membrane and a preparation method and application thereof, wherein the preparation method of the reverse osmosis membrane comprises the following steps: a cationic surfactant, sodium cyclamate and water are mixed into a mixed solution; the mixed solution, an oil solution containing polyacyl chlorides, and a polyvinyl alcohol aqueous solution are sequentially placed on the same surface of a support membrane to form organic nanoparticles, wherein the mass ratio of sodium cyclamate to polyacyl chlorides is 5:1-10:1, and the mass ratio of polyvinyl alcohol to polyacyl chlorides is 1:1-5:1; a polyamide separation layer is prepared on the surface of the support membrane distributed with organic nanoparticles by interfacial polymerization to obtain a reverse osmosis membrane. The reverse osmosis membrane prepared by the preparation method can, when applied to water treatment, have both high water flux and high anti-pollution performance while maintaining high salt retention performance.

Description

Technical Field

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

[0002] Reverse osmosis is a highly efficient and energy-efficient water treatment method that has been widely used in seawater desalination, drinking water treatment, and water reuse. However, existing reverse osmosis membranes still suffer from the problem of not being able to achieve both high water flux and high anti-fouling performance. Summary of the Invention

[0003] Based on this, it is necessary to provide a reverse osmosis membrane and its preparation method and application to address the above problems. When the reverse osmosis membrane prepared by this preparation method is used in water treatment, it can maintain high salt retention performance while having high water flux and high anti-pollution performance.

[0004] A method for preparing a reverse osmosis membrane comprises the following steps:

[0005] A cationic surfactant, sodium cyclamate and water are prepared into a mixed solution;

[0006] placing the mixed solution, the oil solution containing polyacyl chloride, and the polyvinyl alcohol aqueous solution on the same surface of a support film in sequence to form organic nanoparticles, wherein the mass ratio of the sodium cyclamate to the polyacyl chloride is 5:1-10:1, and the mass ratio of the polyvinyl alcohol to the polyacyl chloride is 1:1-5:1;

[0007] A polyamide separation layer is prepared on the surface of the support membrane with organic nanoparticles distributed thereon 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 cyclamate in the mixed solution is 0.5%-5%.

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

[0011] In one embodiment, the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution 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 polybasic acid chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride.

[0014] In one embodiment, in the step of placing the mixed solution, the oil solution containing polyacyl chlorides, and the polyvinyl alcohol aqueous solution on the same surface of a support membrane in sequence to form organic nanoparticles, the mixed solution, the oil solution containing polyacyl chlorides, and the polyvinyl alcohol aqueous solution are placed on the same surface of the support membrane in sequence and subjected to heat treatment to form organic nanoparticles, wherein the heat treatment temperature is 50°C-60°C and the heat treatment time is 3min-5min.

[0015] In one embodiment, in the step of preparing a polyamide separation layer on the surface of the support membrane on which organic nanoparticles are distributed by interfacial polymerization, an aqueous phase solution and an oil phase 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, wherein the aqueous phase solution includes a polyamine and the oil phase solution includes a polyacyl chloride.

[0016] A reverse osmosis membrane prepared by adopting the reverse osmosis membrane preparation method.

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

[0018] In the preparation method of the reverse osmosis membrane of the present invention, when a mixed solution prepared by a cationic surfactant, sodium cyclohexylaminosulfonate and water, an oil solution containing polyacyl chlorides, and a polyvinyl alcohol aqueous solution are sequentially placed on the same surface of a support membrane, sodium cyclohexylaminosulfonate is uniformly distributed at the water-oil interface under the electrostatic action of the cationic surfactant, and by controlling the mass ratio of sodium cyclohexylaminosulfonate, polyvinyl alcohol, and polyacyl chlorides, sodium cyclohexylaminosulfonate will only undergo interfacial polymerization reaction with part of the acyl chloride groups in the polyacyl chlorides, while polyvinyl alcohol will continue to undergo interfacial polymerization reaction with the remaining acyl chloride groups in the polyacyl chlorides. The surface polymerization reaction forms organic nanoparticles with a low degree of cross-linking and uniformly distributed on the surface of the support membrane. On the one hand, the organic nanoparticles can effectively avoid the problem of excessive cross-linking of polyvinyl alcohol and acyl chloride groups affecting the water flux of the reverse osmosis membrane, and at the same time can increase the water production channel accordingly, further improving the water flux of the reverse osmosis membrane. On the other hand, they contain a large number of unreacted hydroxyl groups, which greatly increase the hydrophilicity of the organic nanoparticles themselves, effectively improving the anti-fouling performance of the reverse osmosis membrane, and at the same time make the organic nanoparticles have good compatibility with the subsequently prepared polyamide separation layer, thereby improving its 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 retention performance while having high water flux and high anti-pollution performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0022] Figure 2 This is an electron microscope image of the reverse osmosis membrane prepared in Comparative Example 8 of the present invention. DETAILED DESCRIPTION

[0023] To facilitate understanding of the present invention, the present invention will be described in more detail below. 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 of the present invention more thorough and comprehensive.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments or embodiments and are not intended to limit the present invention. The optional scope 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 related listed items, including any two related listed items, any more related listed items, or the combination of all related listed items.

[0025] The method for preparing a reverse osmosis membrane provided by the present invention comprises the following steps:

[0026] A cationic surfactant, sodium cyclamate and water are prepared into a mixed solution;

[0027] placing the mixed solution, the oil solution containing polyacyl chloride, and the polyvinyl alcohol aqueous solution on the same surface of a support film in sequence to form organic nanoparticles, wherein the mass ratio of the sodium cyclamate to the polyacyl chloride is 5:1-10:1, and the mass ratio of the polyvinyl alcohol to the polyacyl chloride is 1:1-5:1;

[0028] A polyamide separation layer is prepared on the surface of the support membrane with organic nanoparticles distributed thereon by interfacial polymerization to obtain a reverse osmosis membrane.

[0029] In the present invention, when the mixed solution and the oil solution containing the polyacyl chloride are sequentially placed on the same surface of the support membrane, the mixed solution and the oil solution containing the polyacyl chloride are in contact to form a water-oil interface, the cationic surfactant in the mixed solution is evenly distributed at the water-oil interface, and the sodium cyclohexylaminosulfonate and the cationic surfactant attract each other due to electrostatic action. Therefore, under the electrostatic action of the cationic surfactant, the sodium cyclohexylaminosulfonate is also evenly distributed at the water-oil interface. At the same time, the sodium cyclohexylaminosulfonate undergoes an interfacial polymerization reaction with the polyacyl chloride. In this process, by controlling the mass ratio of the sodium cyclohexylaminosulfonate to the polyacyl chloride, the sodium cyclohexylaminosulfonate only undergoes an interfacial polymerization reaction with part of the acyl chloride groups of the polyacyl chloride, so that the polyacyl chloride will have some unreacted acyl chloride groups remaining. Moreover, since the sodium cyclohexylaminosulfonate is evenly distributed at the water-oil interface, the polyacyl chloride reacting with the sodium cyclohexylaminosulfonate is also evenly distributed at the water-oil interface during this process.

[0030] When a polyvinyl alcohol aqueous solution is placed on the same surface of a support membrane, the polyvinyl alcohol will continue to undergo an interfacial polymerization reaction with the remaining acyl chloride groups of the polyacyl chloride to form organic nanoparticles. In this process, by controlling the mass ratio of polyvinyl alcohol to the polyacyl chloride, the crosslinking degree of the two can be effectively controlled, so that the formed organic nanoparticles have a lower crosslinking degree. At the same time, since the polyacyl chloride is evenly distributed at the water-oil interface, the formed organic nanoparticles are then evenly distributed on the surface of the support membrane. On the one hand, the organic nanoparticles can effectively avoid the problem of excessive crosslinking between polyvinyl alcohol and acyl chloride groups affecting the water flux of the reverse osmosis membrane. At the same time, the presence of organic nanoparticles can also increase the water production channels accordingly, further improving 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, effectively improving the anti-fouling performance of the reverse osmosis membrane. At the same time, the organic nanoparticles can have good compatibility with the subsequently prepared polyamide separation layer, thereby improving their firmness in the reverse osmosis membrane.

[0031] In addition, by preparing a polyamide separation layer on the surface of the support membrane on which organic nanoparticles are distributed through interfacial polymerization, the reverse osmosis membrane can be effectively guaranteed to have high salt retention performance. At the same time, the organic nanoparticles are 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 retention performance while having high water flux and high anti-pollution performance.

[0033] It should be noted that, on the one hand, the sodium cyclohexylaminosulfonate in the mixed solution of the present invention can first react with some of the acyl chloride groups of the polyacyl chloride, consuming some of the acyl chloride groups, so that the cross-linking degree of the organic nanoparticles formed by the reaction of polyvinyl alcohol and the polyacyl chloride is low, which can effectively reduce the resistance of the reverse osmosis membrane to water and improve the water flux of the reverse osmosis membrane. In addition, the organic nanoparticles can contain a large number of unreacted hydroxyl groups, have high hydrophilicity, improve the anti-pollution performance of the reverse osmosis membrane, and improve its compatibility with the polyamide separation layer, thereby preventing it from falling off the reverse osmosis membrane. On the other hand, under the action of the cationic surfactant, the sodium cyclohexylaminosulfonate is evenly distributed at the water-oil interface, so that the polyacyl chloride reacting with it is also evenly distributed at the water-oil interface, and then the organic nanoparticles formed by the reaction of polyvinyl alcohol and the polyacyl chloride are evenly distributed on the surface of the support membrane, which can increase the water production channel 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%. By adjusting the amount of the cationic surfactant, sodium cyclamate can be more evenly distributed at the water-oil interface and react with the polyacyl chloride. This, in turn, facilitates a more even distribution of organic nanoparticles formed by the reaction of the polyacyl 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] Furthermore, the cationic surfactant is selected from at least one of dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride.

[0036] Optionally, the mass fraction of sodium cyclohexylaminosulfonate in the mixed solution is 0.5%-5%; the mass fraction of the polyacyl chloride in the oil solution containing the polyacyl chloride is 0.1%-0.5%; and the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 0.1%-2.5%. With this arrangement, by adjusting the mass fraction of sodium cyclohexylaminosulfonate in the mixed solution, the mass fraction of the polyacyl chloride in the oil solution containing the polyacyl chloride, and the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution, the mass ratio of sodium cyclohexylaminosulfonate to the polyacyl chloride, and the mass ratio of polyvinyl alcohol to the polyacyl chloride, can be better controlled, thereby better forming organic nanoparticles with a low degree of cross-linking and uniform distribution, and better improving the water flux and anti-fouling performance of the reverse osmosis membrane.

[0037] Furthermore, the polybasic acyl chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride, preferably trimesoyl chloride. In this arrangement, the amino group of sodium cyclamate first reacts with one acyl chloride group in trimesoyl chloride, leaving two acyl chloride groups in trimesoyl chloride. The remaining two acyl chloride groups in trimesoyl chloride can polymerize with polyvinyl alcohol at the water-oil interface to generate organic nanoparticles with a low degree of crosslinking.

[0038] It can be understood that the oil solution containing polyacyl chloride in the present invention is obtained by mixing polyacyl chloride and an organic solvent, wherein 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 the polyacyl chloride, and the polyvinyl alcohol aqueous solution on the same surface of a support membrane to form the organic nanoparticles, the mixed solution, the oil solution containing the polyacyl chloride, and the polyvinyl alcohol aqueous solution are sequentially placed on the same surface of the support membrane and subjected to heat treatment to form the organic nanoparticles, wherein the heat treatment temperature is 50°C-60°C and the heat treatment time is 3-5 minutes. This arrangement facilitates sufficient reaction of the residual groups of the polyvinyl alcohol and the polyacyl chloride, thereby obtaining organic nanoparticles with a low degree of crosslinking and uniform distribution.

[0040] Alternatively, in the step of forming a polyamide separation layer on the surface of the support membrane on which the organic nanoparticles are distributed by interfacial polymerization, an aqueous solution and an oily solution are sequentially placed on the surface of the support membrane on which the organic nanoparticles are distributed, and then heat-treated to form the polyamide separation layer, wherein the aqueous solution includes a polyamine and the oily solution includes a polyacyl chloride. It is understood that the polyamine and the polyacyl chloride form the polyamide separation layer through interfacial polymerization, thereby ensuring that the reverse osmosis membrane has high salt rejection performance.

[0041] In one embodiment, the mass fraction of the polyamine in the aqueous phase solution is 1%-3%, and the mass fraction of the polyacyl chloride in the oil phase solution is 0.1%-0.5%. This configuration facilitates a sufficient reaction between the polyamine and the polyacyl chloride to form a relatively dense polyamide separation layer, which helps the reverse osmosis membrane maintain high salt rejection performance.

[0042] Furthermore, the polyamine is selected from at least one of m-phenylenediamine, piperazine, p-phenylenediamine, and tetraethylenepentamine, preferably m-phenylenediamine; the polyacyl chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride, and terephthaloyl chloride, preferably trimesoyl chloride.

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

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

[0045] In one embodiment, in the step of forming the polyamide separation layer through heat treatment, the heat treatment temperature is 75°C-100°C, and the heat treatment time is 2-4 minutes. This configuration further ensures the integrity and uniformity of the crosslinking of the polyamide separation layer, further improving the salt retention performance and water flux of the reverse osmosis membrane.

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

[0047] In one embodiment, the support membrane is selected from at least one of a polysulfone membrane, a polypropylene membrane or a polyacrylonitrile membrane, wherein polysulfone is cheap and readily available, simple to prepare, has good mechanical strength, good pressure resistance, stable chemical properties, is non-toxic, and can resist biodegradation. Therefore, the support membrane is preferably a polysulfone membrane.

[0048] The present invention also provides a reverse osmosis membrane prepared using the reverse osmosis membrane preparation method. When used in water treatment, the reverse osmosis membrane can maintain high salt retention performance while also having high water flux and high anti-pollution performance.

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

[0050] In one embodiment, the water treatment device can be a purifier. When the reverse osmosis membrane is used in the 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 passes through the reverse osmosis membrane under pressure to form pure water.

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

[0052] The reverse osmosis membrane, its preparation method, and its application will be further described below by the following specific examples. However, those skilled in the art will understand that the following examples are intended only to illustrate the present invention and should not be construed as limiting the scope of the present invention. Where specific conditions are not specified in the examples, the procedures were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, for which the manufacturer is not specified, are all commercially available conventional products.

[0053] Example 1

[0054] Dodecyltrimethylammonium bromide, sodium cyclohexylaminosulfonate and water are uniformly mixed to prepare a mixed solution, wherein the mass fraction of dodecyltrimethylammonium bromide and the mass fraction of sodium cyclohexylaminosulfonate in the mixed solution is 0.1%, and the mass fraction of sodium cyclohexylaminosulfonate is 5%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil solution containing trimesoyl chloride, wherein the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.5%. Metaphenylenediamine, triethylamine and water are uniformly mixed to prepare an aqueous phase solution, wherein the mass fraction of metaphenylenediamine and triethylamine in the aqueous phase solution is 3%, and the mass fraction of triethylamine is 3%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil phase solution, wherein the mass fraction of trimesoyl chloride in the oil phase solution is 0.4%.

[0055] The mixed solution is applied to the surface of a polysulfone support membrane, and after no obvious liquid droplets are left on the surface, an oil solution containing trimesoyl chloride is applied. After standing for 30 seconds, the excess oil solution is poured out, and the polysulfone support membrane is dried in the shade; then, a polyvinyl alcohol aqueous solution is applied, and the excess polyvinyl alcohol aqueous solution is poured out, and the polysulfone support membrane is dried in the shade to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane, wherein the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 2%, the mass ratio of sodium cyclohexylaminosulfonate to trimesoyl chloride is 10:1, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 4:1.

[0056] The above aqueous solution was applied to the surface of the polysulfone support membrane with organic nanoparticles distributed thereon, and after standing for 60 seconds, the excess aqueous solution was poured out, and the membrane surface was blown dry with cold air. Then, the above oily solution was applied to the same surface of the polysulfone support membrane, and after standing for 30 seconds, the excess oily solution was poured out, and after draining, it was placed in an 80°C oven for 3 minutes to obtain the following: Figure 1 The reverse osmosis membrane shown.

[0057] Example 2

[0058] Dodecyltrimethylammonium bromide, sodium cyclohexylaminosulfonate, and water are uniformly mixed to prepare a mixed solution, wherein the mass fraction of dodecyltrimethylammonium bromide and the mass fraction of sodium cyclohexylaminosulfonate in the mixed solution is 0.05%, and the mass fraction of sodium cyclohexylaminosulfonate is 2.1%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil solution containing trimesoyl chloride, wherein the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.3%. Metaphenylenediamine, triethylamine, and water are uniformly mixed to prepare an aqueous phase solution, wherein the mass fraction of metaphenylenediamine and triethylamine in the aqueous phase solution is 2%, and the mass fraction of triethylamine is 2%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil phase solution, wherein the mass fraction of trimesoyl chloride in the oil phase solution is 0.3%.

[0059] The above mixed solution is applied to the surface of a polysulfone support membrane. After no obvious liquid droplets are left on the surface, an oil solution containing trimesoyl chloride is applied. After standing for 30 seconds, the excess oil solution is poured out, and the polysulfone support membrane is dried in the shade. Then, a polyvinyl alcohol aqueous solution is applied, and the excess polyvinyl alcohol aqueous solution is poured out, and the polysulfone support membrane is dried in the shade to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane, wherein the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 0.9%, the mass ratio of sodium cyclohexylaminosulfonate to trimesoyl chloride is 7:1, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 3:1.

[0060] The above-mentioned aqueous phase solution was applied to the surface of the polysulfone support membrane distributed with organic nanoparticles. After standing for 60 seconds, the excess aqueous phase solution was poured out and the membrane surface was blown dry with cold air. Then, the above-mentioned oil phase solution was applied to the same surface of the polysulfone support membrane. After standing for 30 seconds, the excess oil phase solution was poured out. After draining, it was placed in a 90°C oven for 2 minutes to obtain a reverse osmosis membrane.

[0061] Example 3

[0062] Dodecyltrimethylammonium bromide, sodium cyclohexylaminosulfonate and water are uniformly mixed to prepare a mixed solution, wherein the mass fraction of dodecyltrimethylammonium bromide and the mass fraction of sodium cyclohexylaminosulfonate in the mixed solution is 0.01%, and the mass fraction of sodium cyclohexylaminosulfonate is 0.5%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil solution containing trimesoyl chloride, wherein the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.1%. Metaphenylenediamine, triethylamine and water are uniformly mixed to prepare an aqueous phase solution, wherein the mass fraction of metaphenylenediamine and triethylamine in the aqueous phase solution is 1%, and the mass fraction of triethylamine is 2%. Trimesoyl chloride and an isoparaffin solvent (Isopar-L) are uniformly mixed to prepare an oil phase solution, wherein the mass fraction of trimesoyl chloride in the oil phase solution is 0.1%.

[0063] The mixed solution is applied to the surface of a polysulfone support membrane, and after no obvious liquid droplets are left on the surface, an oil solution containing trimesoyl chloride is applied. After standing for 30 seconds, the excess oil solution is poured out, and the polysulfone support membrane is dried in the shade; then, a polyvinyl alcohol aqueous solution is applied, and the excess polyvinyl alcohol aqueous solution is poured out, and the polysulfone support membrane is dried in the shade to obtain organic nanoparticles uniformly distributed on the surface of the polysulfone support membrane, wherein the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 0.1%, the mass ratio of sodium cyclohexylaminosulfonate to trimesoyl chloride is 5:1, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 1:1.

[0064] The above-mentioned aqueous phase solution was applied to the surface of the polysulfone support membrane distributed with organic nanoparticles. After standing for 60 seconds, the excess aqueous phase solution was poured out and the membrane surface was blown dry with cold air. Then, the above-mentioned oil phase solution was applied to the same surface of the polysulfone support membrane. After standing for 30 seconds, the excess oil phase solution was poured out. After draining, it was placed in an 85°C oven for 3 minutes to obtain a reverse osmosis membrane.

[0065] Example 4

[0066] Compared with Example 1, Example 4 differs only in that the mass fraction of dodecyltrimethylammonium bromide in the mixed solution is 0.005%, and the other conditions are the same to obtain a reverse osmosis membrane.

[0067] Example 5

[0068] Compared with Example 1, Example 5 differs only in that the mass fraction of dodecyltrimethylammonium bromide in the mixed solution is 0.2%, and the other conditions are the same to obtain a reverse osmosis membrane.

[0069] Example 6

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

[0071] Example 7

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

[0073] Example 8

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

[0075] Example 9

[0076] Compared with Example 1, Example 9 differs only in that the mass fraction of trimesoyl chloride in the oil solution containing trimesoyl chloride is 0.6%. Other conditions are the same, and a reverse osmosis membrane is obtained.

[0077] Example 10

[0078] Compared with Example 1, Example 10 differs only in that the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 0.05%, and other conditions are the same to obtain a reverse osmosis membrane.

[0079] Example 11

[0080] Compared with Example 1, Example 11 differs only in that the mass fraction of polyvinyl alcohol in the polyvinyl alcohol aqueous solution is 3%, and other conditions are the same to obtain a reverse osmosis membrane.

[0081] Example 12

[0082] Compared with Example 1, Example 12 differs only in that dodecyltrimethylammonium chloride is used instead of dodecyltrimethylammonium bromide in the mixed solution, and other conditions are the same to obtain a reverse osmosis membrane.

[0083] Example 13

[0084] Compared with Example 1, Example 13 differs only in that isophthaloyl chloride is used instead of trimesoyl chloride. Other conditions are the same to obtain a reverse osmosis membrane.

[0085] Example 14

[0086] The only difference between Example 14 and Example 1 is that a polyvinyl alcohol aqueous solution is then applied, and then the excess polyvinyl alcohol aqueous solution is poured out. The polysulfone support membrane is dried in the shade and placed in a 60°C oven for 3 minutes to obtain organic nanoparticles evenly distributed on the surface of the polysulfone support membrane. The other conditions are the same to obtain a reverse osmosis membrane.

[0087] Comparative Example 1

[0088] Comparative Example 1 is different from Example 1 only in that the mixed solution does not contain sodium cyclamate. Other conditions are the same to obtain a reverse osmosis membrane.

[0089] Comparative Example 2

[0090] Comparative Example 2 is different from Example 1 only in that the mixed solution does not contain dodecyltrimethylammonium bromide. Other conditions are the same, and a reverse osmosis membrane is obtained.

[0091] Comparative Example 3

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

[0093] Comparative Example 4

[0094] Comparative Example 4 is compared with Example 1, except 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%, the mass ratio of sodium cyclamate to trimesoyl chloride is 50:1, and the other conditions are the same to obtain a reverse osmosis membrane.

[0095] Comparative Example 5

[0096] Comparative Example 5 is compared with Example 1, except 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%, the mass ratio of sodium cyclamate to trimesoyl chloride is 1:1, and the other conditions are the same to obtain a reverse osmosis membrane.

[0097] Comparative Example 6

[0098] Comparative Example 6 is compared with Example 1, except 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 polyvinyl alcohol aqueous solution is 0.15%, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 1:2. The other conditions are the same, and a reverse osmosis membrane is obtained.

[0099] Comparative Example 7

[0100] Comparative Example 7 is compared with Example 1, except 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 polyvinyl alcohol aqueous solution is 6%, and the mass ratio of polyvinyl alcohol to trimesoyl chloride is 15:1. The other conditions are the same, and a reverse osmosis membrane is obtained.

[0101] Comparative Example 8

[0102] Comparative Example 8 is different from Example 1 only in that a glutaraldehyde aqueous solution is used instead of the oil solution containing trimesoyl chloride, wherein the mass fraction of glutaraldehyde in the glutaraldehyde aqueous 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. Other conditions are the same, and the following is obtained: Figure 2 The reverse osmosis membrane shown.

[0103] The reverse osmosis membranes prepared in Examples 1 to 14 and Comparative Examples 1 to 8 were subjected to performance tests. The test conditions were as follows: a test pressure of 1.55 MPa, a brine flow rate of 1.0 GPM, an ambient temperature of 25°C, a brine pH of 6.5-7.5, and a brine solution of 2000 ppm sodium chloride. The test results are shown in Table 1.

[0104] Table 1

[0105]

[0106] At the same time, the anti-pollution performance of the reverse osmosis membranes prepared in Examples 1 to 14 and Comparative Examples 1 to 8 was tested. The test conditions were as follows: the test pressure was 1.55 MPa, the brine flow rate was 1.0 GPM, the ambient temperature was 25°C, the brine pH value was 6.5-7.5, and the brine was 2000 ppm sodium chloride + 100 ppm sodium humate + 100 ppm bovine serum albumin as the inlet water condition. The anti-pollution performance test was carried out. After 100 hours of continuous operation, the membrane was cleaned, and then the performance test was carried out under the condition of 2000 ppm sodium chloride inlet water of brine. The test results are shown in Table 2.

[0107] Table 2

[0108]

[0109] It should be noted that in Tables 1 and 2, the membrane water flux (F) is calculated by the volume of water passing through the reverse osmosis membrane in a certain period of time, using the formula: 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 time.

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

[0111] The calculation formula of water flux recovery rate is: (water flux of reverse osmosis membrane after pollution / water flux of 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 leaves, 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, which is beneficial to increase the specific surface area of the reverse osmosis membrane and improve the water flux.

[0113] from Figure 2 It can be seen that since the glutaraldehyde aqueous solution is used instead of the oil solution containing trimesoyl chloride in Comparative Example 8, the cross-linking density of the formed organic nanoparticles is high, resulting in an increase in the number of particles on the surface of the prepared reverse osmosis membrane and fewer leaf-like morphologies, which in turn affects the water flux of the reverse osmosis membrane.

[0114] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0115] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for preparing a reverse osmosis membrane, characterized in that: The steps include: A cationic surfactant, sodium cyclamate and water are prepared into a mixed solution; placing the mixed solution, the oil solution containing polyacyl chloride, and the polyvinyl alcohol aqueous solution on the same surface of a support film in sequence to form organic nanoparticles, wherein the mass ratio of the sodium cyclamate to the polyacyl chloride is 5:1-10:1, and the mass ratio of the polyvinyl alcohol to the polyacyl chloride is 1:1-5:1; A polyamide separation layer is prepared on the surface of the support membrane with organic nanoparticles distributed thereon by interfacial polymerization to obtain a reverse osmosis membrane.

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

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

4. The method for preparing a reverse osmosis membrane according to claim 1, wherein The mass fraction of the polyacyl chloride in the oil solution containing the polyacyl chloride is 0.1%-0.5%.

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

6. The method for preparing a reverse osmosis membrane according to claim 1, wherein The cationic surfactant is selected from at least one of dodecyltrimethylammonium bromide and dodecyltrimethylammonium chloride; And / or, the polybasic acid chloride is selected from at least one of trimesoyl chloride, isophthaloyl chloride and terephthaloyl chloride.

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

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 on which organic nanoparticles are distributed by interfacial polymerization, an aqueous phase solution and an oil phase solution are placed sequentially on the surface of the support membrane on which organic nanoparticles are distributed, and then heat-treated to form a polyamide separation layer, wherein the aqueous phase solution includes a polyamine and the oil phase solution includes a polyacyl chloride.

9. A reverse osmosis membrane prepared by the method for preparing a reverse osmosis membrane according to any one of claims 1 to 8.

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

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