Method for producing a reverse osmosis membrane and reverse osmosis membrane produced thereby

Abstract

This invention relates to a method for preparing a reverse osmosis membrane and the reverse osmosis membrane prepared therefrom. The method includes: preparing a base membrane comprising a support material and a polymer layer on the support material; contacting the base membrane with an aqueous solution containing amine monomers and a two-dimensional layered material; subsequently contacting it with an oil solution containing acyl chloride monomers, an antioxidant, and an organotin catalyst; and post-treatment. This method requires no modification to existing equipment, can utilize existing production lines, and is simple and highly efficient. The reverse osmosis membrane prepared by this method maintains high flux and desalination rate while exhibiting better temperature resistance and oxidation resistance; after oxidation at 45°C, the variation in flux and desalination rate both show a significant decrease.

Description

Technical Field

[0001] This invention relates to a method for preparing a reverse osmosis membrane and a reverse osmosis membrane prepared therefrom, and more specifically to a temperature-resistant and oxidation-resistant reverse osmosis membrane. Background Technology

[0002] Aromatic polyamide composite reverse osmosis membranes have been widely used in drinking water purification, medical and pharmaceutical applications, municipal water supply, and seawater desalination due to their advantages of low operating pressure and the ability to remove 99% of ionic substances under neutral conditions. However, in practical applications, aromatic polyamide composite reverse osmosis membranes are susceptible to heat and oxidation. Under long-term operating conditions, excessively high temperatures can cause the membrane pores to close, severely affecting the membrane's permeation efficiency. Free radicals can also cause irreversible damage to the polyamide membrane material, leading to a significant decline in membrane performance and failure to meet application requirements. These problems severely restrict the further application and development of polyamide reverse osmosis membranes.

[0003] Existing technologies for improving the antioxidant properties of membranes mainly include surface grafting modification (e.g., CN120420839B, CN118987994A, CN117160254A) and coating modification (e.g., CN114082307A). Although these modification methods can improve the antioxidant properties of membranes to a certain extent, their durability is poor.

[0004] Existing technologies for improving the temperature resistance of membranes mainly include improving the temperature resistance of the support layer or introducing inorganic materials such as CN116272418A, CN106914153A, and CN107126851A into the support layer. However, these improvement methods have not improved the temperature resistance of the desalination layer. In addition, the modification of inorganic materials also increases the complexity of the operation steps. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a new preparation method that can simultaneously improve the temperature resistance and oxidation resistance of reverse osmosis membranes.

[0007] Solution for solving the problem

[0008] In order to achieve the above objectives, the inventors of this invention conducted in-depth research and discovered that:

[0009] By introducing two-dimensional layered materials into an aqueous solution, the temperature resistance and oxidation resistance of the membrane can be improved. Furthermore, by adding antioxidants and catalysts to an oil solution and forming surface-modified layered materials through in-situ condensation, the interfacial compatibility and oxidation resistance of the membrane can be improved.

[0010] The two-dimensional layered material includes hydrotalcite, whose surface is rich in hydroxyl groups and possesses certain free radical scavenging activity. It exhibits good compatibility with the aqueous phase, and its introduction can improve the temperature resistance and oxidation resistance of the membrane to a certain extent. Furthermore, distearate thiodipropionate is added to the oil phase solution as an antioxidant, and a high-boiling-point organotin catalyst such as dibutyltin dilaurate is added. During heating, this catalyst catalyzes the reaction, causing the hydroxyl groups on the hydrotalcite surface to... ) and the carboxyl group of distearate thiodipropionate ( The surface modification of hydrotalcite is completed during the interfacial polymerization process through a combination of dehydration condensation reaction. The layered structure of hydrotalcite provides a stable carrier for antioxidants, while the surface modification of antioxidants enhances the interfacial compatibility between hydrotalcite and polyamide. This interaction jointly promotes the improvement of the temperature resistance and antioxidant properties of polyamide reverse osmosis membranes.

[0011] The method for preparing the reverse osmosis membrane of the present invention includes the following steps:

[0012] Prepare a base film, the base film comprising a support material and a polymer layer on the support material;

[0013] The base film is brought into contact with an aqueous solution containing amine monomers and two-dimensional layered materials;

[0014] It is then contacted with an oil phase solution containing acyl chloride monomers, antioxidants, and organotin catalysts;

[0015] Post-processing.

[0016] In the preparation method of the present invention, the supporting material is a nonwoven fabric, the polymer layer is formed by a casting solution, the casting solution contains a polymer and a solvent, and the polymer is at least one selected from bisphenol A polysulfone, polyethersulfone, polyacrylonitrile, polyimide, and polyvinylidene fluoride.

[0017] The preparation method of the present invention, wherein the two-dimensional layered material comprises hydrotalcite, preferably, the concentration of the two-dimensional layered material is 0.001wt%~10wt% based on the total weight of the aqueous solution.

[0018] The preparation method of the present invention, wherein the antioxidant comprises distearate thiodipropionate, preferably, the concentration of the antioxidant is 0.01wt%~5wt% based on the total weight of the oil phase solution.

[0019] The preparation method of the present invention, wherein the organotin catalyst comprises dibutyltin dilaurate, preferably, the concentration of the organotin catalyst is 0.01wt%~5wt% based on the total weight of the oil phase solution.

[0020] In the preparation method of the present invention, the amine monomer is selected from at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, biphenylenediamine, p-aminophenol, 2,4-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminophenol, 3,5-diaminobenzoic acid, and 1,5-diaminonaphthalene. Preferably, the concentration of the amine monomer is 0.1 wt% to 10 wt% based on the total weight of the aqueous solution.

[0021] In the preparation method of the present invention, the acyl chloride monomer is selected from at least one of pyromellitic trimethylolpropionate, isophthaloyl chloride, biphenyl dimethylolpropionate, and terephthaloyl chloride. Preferably, the concentration of the acyl chloride monomer is 0.01wt% to 10wt% based on the total weight of the oil phase solution.

[0022] The preparation method of the present invention further includes an acid acceptor in the aqueous phase solution. Preferably, the acid acceptor includes sodium hydroxide. More preferably, the concentration of the acid acceptor is 0.001 wt% to 10 wt% based on the total weight of the aqueous phase solution.

[0023] The preparation method of the present invention includes heat treatment in the post-processing.

[0024] The present invention also provides a reverse osmosis membrane prepared by the above method.

[0025] The effects of the invention

[0026] The preparation method of this invention requires no modification to existing equipment and can utilize existing production lines, resulting in a simple process and high production efficiency. The reverse osmosis membrane prepared by this method maintains high flux and desalination rate while exhibiting better temperature and oxidation resistance; after oxidation at 45°C, the variation in flux and desalination rate both show a significant decrease. Detailed Implementation

[0027] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0028] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0029] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0030] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0031] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0032] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0033] The method for preparing the reverse osmosis membrane of the present invention includes the following steps:

[0034] Prepare a base film, the base film comprising a support material and a polymer layer on the support material;

[0035] The base film is brought into contact with an aqueous solution containing amine monomers and two-dimensional layered materials;

[0036] It is then contacted with an oil phase solution containing acyl chloride monomers, antioxidants, and organotin catalysts;

[0037] Post-processing.

[0038] In the preparation method of the present invention, the supporting material is a nonwoven fabric, the polymer layer is formed by a casting solution, the casting solution contains a polymer and a solvent, and the polymer is at least one selected from bisphenol A polysulfone, polyethersulfone, polyacrylonitrile, polyimide, and polyvinylidene fluoride.

[0039] There are no particular limitations on the solvent, as long as it can dissolve the polymer. For example, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone can be used. Preferably, based on the total weight of the casting solution, the concentration of the polymer is 10wt% to 40wt%, more preferably 15wt% to 35wt%.

[0040] The preparation method of the present invention, wherein the two-dimensional layered material comprises hydrotalcite, preferably, the concentration of the two-dimensional layered material is 0.001wt%~10wt% based on the total weight of the aqueous solution, more preferably, the concentration is 0.01wt%~1wt%.

[0041] The preparation method of the present invention, wherein the antioxidant comprises distearate thiodipropionate, preferably, the concentration of the antioxidant is 0.01wt% to 5wt% based on the total weight of the oil phase solution, more preferably, the concentration is 0.01wt% to 1wt%.

[0042] The preparation method of the present invention, wherein the organotin catalyst comprises dibutyltin dilaurate, preferably, based on the total weight of the oil phase solution, the concentration of the organotin catalyst is 0.01wt%~5wt%, more preferably, the concentration is 0.01wt%~1wt%.

[0043] In the preparation method of the present invention, the amine monomer is selected from at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, biphenylenediamine, p-aminophenol, 2,4-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminophenol, 3,5-diaminobenzoic acid, and 1,5-diaminonaphthalene. Preferably, based on the total weight of the aqueous solution, the concentration of the amine monomer is 0.1 wt% to 10 wt%, more preferably, the concentration is 1 wt% to 5 wt%.

[0044] In the preparation method of the present invention, the acyl chloride monomer is selected from at least one of pyromellitic methyl methacrylate, isophthaloyl chloride, biphenyl methyl methacrylate, and terephthaloyl chloride. Preferably, based on the total weight of the oil phase solution, the concentration of the acyl chloride monomer is 0.01wt% to 10wt%, more preferably, the concentration is 0.01wt% to 5wt%.

[0045] The preparation method of the present invention further includes an acid acceptor in the aqueous phase solution. Preferably, the acid acceptor includes sodium hydroxide. More preferably, the concentration of the acid acceptor is 0.001 wt% to 10 wt% based on the total weight of the aqueous phase solution. More preferably, the concentration is 0.01 wt% to 1 wt%.

[0046] The preparation method of the present invention includes a heat treatment, wherein the heat treatment temperature can be 40~100℃, preferably 60~90℃.

[0047] The present invention also provides a reverse osmosis membrane prepared by the above method.

[0048] Example

[0049] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0050] Example 1

[0051] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried and then immersed in an oil solution containing 0.18 wt% trimesoyl chloride for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0052] Example 2

[0053] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine, 0.01 wt% hydrotalcite, and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried and then immersed in an oil solution containing 0.18 wt% trimesoyl chloride for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0054] Example 3

[0055] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine, 0.05 wt% hydrotalcite, and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried and then immersed in an oil solution containing 0.18 wt% trimesoyl chloride for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0056] Example 4

[0057] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine, 0.1 wt% hydrotalcite, and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried and then immersed in an oil solution containing 0.18 wt% trimesoyl chloride for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0058] Example 5

[0059] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine, 0.05 wt% hydrotalcite, and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried. Then, it was immersed in an oil solution containing 0.18 wt% trimesoyl chloride, 0.1 wt% distearate thiodipropionate, and 0.01 wt% dibutyltin dilaurate for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0060] Example 6

[0061] Bisphenol A type polysulfone-based membrane was immersed on one side in an aqueous solution containing 4 wt% m-phenylenediamine, 0.05 wt% hydrotalcite, and 0.02 wt% sodium hydroxide for 1 min. After immersion, the membrane surface was dried. Then, it was immersed in an oil solution containing 0.18 wt% trimesoyl chloride, 0.5 wt% distearate thiodipropionate, and 0.05 wt% dibutyltin dilaurate for 30 s. After the reaction was completed, the membrane was removed and dried at 70 °C to obtain a polyamide reverse osmosis membrane.

[0062] The flux and desalination rate of the reverse osmosis membranes obtained in the above examples, as well as the flux and desalination rate after one day of oxidation operation, were tested. The test conditions were: NaCl: 2000 ppm, pressure 225 psi, temperature 25℃, pH: 7; oxidation operation conditions: hydrogen peroxide: 10000 ppm, pressure 225 psi, temperature 45℃. The test results are listed in Table 1 below.

[0063] Table 1

[0064]

[0065] Comparing the test results of Examples 1 to 4 and Examples 5 to 6, it can be seen that the reverse osmosis membrane prepared by the method of the present invention, while maintaining a high flux and desalination rate, shows a significant decrease in the variation range of flux and desalination rate after oxidation at 45°C, thus exhibiting better temperature resistance and oxidation resistance.

[0066] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0067] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for producing a reverse osmosis membrane, characterized by, It includes the following steps: Prepare a base film, the base film comprising a support material and a polymer layer on the support material; The base film is contacted with an aqueous solution containing amine monomers and a two-dimensional layered material, wherein the two-dimensional layered material contains hydrotalcite. It is then contacted with an oil phase solution containing acyl chloride monomers, antioxidants, and organotin catalysts, wherein the antioxidants include distearate thiodipropionate and the organotin catalysts include dibutyltin dilaurate. Post-processing.

2. The preparation method according to claim 1, wherein the support material is a nonwoven fabric, the polymer layer is formed by a casting solution, the casting solution comprises a polymer and a solvent, and the polymer is at least one selected from bisphenol A polysulfone, polyethersulfone, polyacrylonitrile, polyimide, and polyvinylidene fluoride.

3. The preparation method according to claim 1 or 2, wherein the concentration of the two-dimensional layered material is 0.001wt% to 10wt% based on the total weight of the aqueous solution.

4. The preparation method according to claim 1 or 2, wherein the concentration of the antioxidant is 0.01wt% to 5wt% based on the total weight of the oil phase solution.

5. The preparation method according to claim 1 or 2, wherein the concentration of the organotin catalyst is 0.01wt% to 5wt% based on the total weight of the oil phase solution.

6. The preparation method according to claim 1 or 2, wherein the amine monomer is selected from at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, biphenylenediamine, p-aminophenol, 2,4-diaminobenzenesulfonic acid, 3,5-diaminobenzenesulfonic acid, 2,4-diaminotoluene, 2,6-diaminotoluene, 2,4-diaminophenol, 3,5-diaminobenzoic acid, and 1,5-diaminonaphthalene.

7. The preparation method according to claim 1 or 2, wherein the concentration of the amine monomer is 0.1 wt% to 10 wt% based on the total weight of the aqueous solution.

8. The preparation method according to claim 1 or 2, wherein the acyl chloride monomer is at least one selected from pyromellitic methyl methacrylate, isophthaloyl chloride, biphenyl methyl methacrylate, and terephthaloyl chloride.

9. The preparation method according to claim 1 or 2, wherein the concentration of the acyl chloride monomer is 0.01wt% to 10wt% based on the total weight of the oil phase solution.

10. The preparation method according to claim 1 or 2, wherein the aqueous phase solution further comprises an acid acceptor.

11. The preparation method according to claim 10, wherein the acid acceptor comprises sodium hydroxide.

12. The preparation method according to claim 10, wherein the concentration of the acid acceptor is 0.001 wt% to 10 wt% based on the total weight of the aqueous solution.

13. The preparation method according to claim 1 or 2, wherein the post-treatment comprises heat treatment.

14. A reverse osmosis membrane prepared by the method according to any one of claims 1 to 13.

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