A high-flux polyamide reverse osmosis membrane, a preparation method and application thereof

Abstract

The application discloses a preparation method of a high-flux polyamide reverse osmosis membrane and application thereof. The method comprises the following steps: after a porous support layer substrate membrane is contacted with an aqueous phase solution containing a multifunctional amine, the excess aqueous phase solution is removed, and then the porous support layer substrate membrane is contacted with an organic phase solution containing a multifunctional acyl chloride, and an interfacial polymerization reaction is performed to form a polyamide reverse osmosis membrane; further, the membrane is soaked in a water solution containing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) for treatment, and then the membrane is cleaned to obtain a high-flux polyamide reverse osmosis membrane. The preparation method is simple and easy to scale up, the prepared polyamide reverse osmosis membrane can significantly improve the water flux on the basis of keeping a relatively high desalination rate. The membrane provided by the application can be used in the fields of household water purifiers and industrial wastewater treatment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reverse osmosis membrane preparation, and particularly relates to a high-flux polyamide reverse osmosis membrane and a preparation method and application thereof. BACKGROUND

[0002] With the growth of global population and the acceleration of industrialization process, water resource shortage has become an increasingly serious problem. Reverse osmosis technology has become one of the core technologies in the field of water treatment due to its high efficiency and energy saving. Two important indicators for evaluating the performance of reverse osmosis membranes are desalination rate and flux, and among them, high-flux reverse osmosis membranes can achieve higher water flux under the same pressure, which means that more water sources can be treated in the same time, thereby shortening the processing period, reducing the equipment floor area, and further improving the economic benefits.

[0003] Generally, increasing the flux of reverse osmosis membranes will cause the desalination rate to decrease, and overcoming the "trade-off" effect between the flux and the desalination rate of reverse osmosis membranes has always been a hot issue in the field of reverse osmosis membrane preparation. For example, Lee et al. added dimethyl sulfoxide (DMSO) to the water phase as a co-solvent, which increased the flux of the membrane by about 75%, but also caused the desalination rate to decrease by about 6% (Lee J, Wang R, Bae T H. A comprehensive understanding of co-solvent effects on interfacial polymerization: interaction with trimesoyl chloride [J]. Journal of Membrane Science, 2019, 583: 70-80.); Shen et al. added silicon tetrachloride to the oil phase, thereby forming silica nanoparticles in situ during the interfacial polymerization process, which increased the flux of the membrane by about 102%, but decreased the desalination rate by about 1.5% (Shen H M, Wang S H, Xu H, Zhou Y, Gao C J. Preparation of polyamide thin film nanocomposite membranes containing silica nanoparticles via an in-situ polymerization of SiCl4 in organic solution [J]. Journal of Membrane Science, 2018, 565: 145-156.).

[0004] Therefore, there is an urgent need in the art for a simple and feasible technical solution that can improve the flux of reverse osmosis membranes while maintaining a relatively high desalination rate. SUMMARY

[0005] To solve the above technical problems, one of the purposes of the present application is to provide a method for preparing a high-flux polyamide reverse osmosis membrane, which is simple, easy to scale up, and can significantly improve the flux of the reverse osmosis membrane.

[0006] To achieve the above-mentioned purposes, the technical solutions adopted by the present application are as follows:

[0007] A method for preparing a high-flux polyamide reverse osmosis membrane, the method comprising the following steps:

[0008] S1: After the porous support layer base membrane is contacted with an aqueous solution containing a multifunctional amine, the excess aqueous phase is removed, and then the porous support layer base membrane is contacted with an organic phase solution containing a multifunctional acyl chloride to perform an interfacial polymerization reaction to obtain a polyamide reverse osmosis membrane F1;

[0009] S2: F1 is soaked in an aqueous solution containing 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) to obtain a polyamide reverse osmosis membrane F2;

[0010] S3: F2 is washed to obtain a high-flux polyamide reverse osmosis membrane.

[0011] In an embodiment of the present application, the multifunctional amine in S1 is an aromatic amine containing at least two primary amine groups, preferably one or more of m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, and 2,6-diaminotoluene, more preferably m-phenylenediamine, and the concentration of the multifunctional amine in the aqueous solution is 1.0-10 wt%, preferably 2.0-5.0 wt%.

[0012] Preferably, the porous support layer base membrane is contacted with the aqueous solution at room temperature for 10-60 s.

[0013] In an embodiment of the present application, the multifunctional acyl chloride in S1 is an aromatic polyacyl chloride, preferably one or more of trimesoyl chloride, isophthaloyl chloride, and naphthalene dicarboxylic chloride, more preferably trimesoyl chloride, and the concentration of the multifunctional acyl chloride in the organic phase solution is 0.01-1.0 wt%, preferably 0.1-0.25 wt%; preferably, the solvent of the organic phase solution of the multifunctional acyl chloride is one or more of n-hexane, Isopar G, and Isopar L.

[0014] Preferably, the porous support layer base membrane is contacted with the organic phase solution containing the multifunctional acyl chloride at room temperature for 10-60 s.

[0015] In an embodiment of the present application, the porous support layer base film can be selected from at least one of polysulfone, polyethersulfone, polyarylether, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene and polyaryletherketone base materials; and the preparation of the porous support layer base film is also a common process in the art, which can be prepared by a person skilled in the art using conventional methods.

[0016] The method for contacting the porous support layer base film with the aqueous phase and organic phase solution is a common method in the art, including soaking, spraying, back coating, coating and the like.

[0017] In an embodiment of the present application, the concentration of the aqueous 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) solution in S2 is 1-20 wt%, preferably 5-15 wt%; the temperature of the aqueous 1,8-diazabicyclo[5.4.0]undec-7-ene solution is 0-90℃, preferably 25-50℃; and the soaking time is 30-300s, preferably 60-120s.

[0018] In an embodiment of the present application, the cleaning in S3 is cleaning in 70-90℃ pure water for 60-300s.

[0019] Another object of the present application is to provide a high-flux polyamide reverse osmosis membrane prepared by the above preparation method.

[0020] Another object of the present application is to provide the use of the above high-flux polyamide reverse osmosis membrane, which is used as a high-flux reverse osmosis membrane and applied in the fields of household water purifiers and industrial wastewater treatment.

[0021] The present application uses an organic strong base 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) solution to post-treat and modify the polyamide reverse osmosis membrane obtained after interfacial polymerization, and the main principle is as follows: on the one hand, DBU can promote the hydrolysis of a large amount of residual acyl chloride in the membrane, thereby forming more carboxyl groups and further increasing the hydrophilicity of the membrane; on the other hand, DBU can promote the further reaction of residual acyl chloride and amino groups in the membrane, thereby increasing the crosslinking degree of the polyamide layer.

[0022] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0023] The preparation method of the present application is simple and easy to scale up, and the prepared polyamide reverse osmosis membrane can significantly improve the water flux (95-110 LMH) while maintaining a relatively high desalination rate (98.6-99.3%). DETAILED DESCRIPTION

[0024] For better understanding of the technical solutions of the present application, the content of the present application will be further described below in combination with examples, but the content of the present application is not limited to the following examples only, and should also include any other known changes within the scope of the claims of the present application.

[0025] The raw materials used in the following examples or comparative examples, if not specifically stated, are all commercially available conventional raw materials, and the main raw material information is shown in Table 1.

[0026] Table 1 Main raw material information

[0027]

[0028] Evaluation of polyamide reverse osmosis membrane flux and desalination rate:

[0029] Desalination rate and permeation flux are two important parameters for evaluating the separation performance of reverse osmosis membranes. According to GB / T32373-2015 "Reverse Osmosis Membrane Test Method", the separation performance of reverse osmosis membranes is evaluated.

[0030] Desalination rate (R) is defined as the difference between the salt concentration (C f ) of the feed liquid and the salt concentration (C p ) in the permeate under certain operating conditions, divided by the salt concentration (C f ) of the feed liquid, as shown in formula (1).

[0031]

[0032] Permeation flux is defined as the volume of water per unit membrane area per unit time under certain operating conditions, and its unit is L·m -2 ·h -1 .

[0033] The operating conditions for measuring the performance of reverse osmosis membranes in the present application are as follows: the feed liquid is a 1500 ppm sodium chloride aqueous solution, the solution pH is 7.5±0.5, the operating pressure is 1.03 MPa, and the operating temperature is 25±0.5℃.

[0034] Preparation of polysulfone support layer: a 16.5wt% polysulfone resin solution in N,N-dimethylformamide (DMF) is uniformly coated on a polyester non-woven fabric substrate at 25℃, the thickness of the wet coating layer is 150μm, after staying in air for 1.5s, it is immersed in deionized water at room temperature for 1min, and then immersed in deionized water at 70℃ for 2min, to obtain a base film containing non-woven fabric substrate and polysulfone porous support layer.

[0035] Example 1

[0036] S1: prepare a water phase solution with 2.0wt% m-phenylenediamine and an organic phase solution with 0.1wt% trimesoyl chloride in Isopar G; immerse the porous polysulfone substrate in the water phase solution for 30s at room temperature, remove the excess water phase solution on the substrate surface by using a squeeze roller, then evenly coat the organic phase solution on the substrate surface, and let it stand for 30s at room temperature for interfacial polymerization, then remove the excess organic phase solution by air knife blowing until no solvent remains on the substrate surface.

[0037] S2: immerse the reverse osmosis membrane obtained in S1 in a water solution containing 15wt% DBU, at a temperature of 25℃ for 60s.

[0038] S3: immerse the reverse osmosis membrane obtained in S2 in pure water at 85℃ for 60s to obtain a polyamide reverse osmosis membrane. The performance test results are shown in Table 2.

[0039] Example 2

[0040] Prepare the reverse osmosis membrane according to the procedure of Example 1, except that the DBU solution concentration is 10wt%, the temperature is 40℃, and the immersion time is 90s, and the other conditions are the same as in Example 1. The performance test results are shown in Table 2.

[0041] Example 3

[0042] Prepare the reverse osmosis membrane according to the procedure of Example 1, except that the DBU solution concentration is 5wt%, the temperature is 50℃, and the immersion time is 120s, and the other conditions are the same as in Example 1. The performance test results are shown in Table 2.

[0043] Example 4

[0044] Prepare the reverse osmosis membrane according to the procedure of Example 1, except that the DBU solution concentration is 1wt%, the temperature is 90℃, and the immersion time is 300s, and the other conditions are the same as in Example 1. The performance test results are shown in Table 2.

[0045] Example 5

[0046] Prepare the reverse osmosis membrane according to the procedure of Example 1, except that the DBU solution concentration is 20wt%, the temperature is 20℃, and the immersion time is 30s, and the other conditions are the same as in Example 1. The performance test results are shown in Table 2.

[0047] Example 6

[0048] Prepare the reverse osmosis membrane according to the procedure of Example 1, except that the concentration of m-phenylenediamine in the water phase solution is 4wt%, and the concentration of trimesoyl chloride in the organic phase solution is 0.2wt%, and the other conditions are the same as in Example 1. The performance test results are shown in Table 2.

[0049] Example 7

[0050] The reverse osmosis membrane was prepared according to the procedure of Example 1, except that the m-phenylenediamine concentration in the aqueous solution was 5 wt%, the trimesoyl chloride concentration in the organic solution was 0.25 wt%, and the other conditions were the same as those in Example 1. The performance test results are shown in Table 2.

[0051] Example 8

[0052] The reverse osmosis membrane was prepared according to the procedure of Example 1, except that the m-phenylenediamine concentration in the aqueous solution was 1.5 wt%, the trimesoyl chloride concentration in the organic solution was 0.08 wt%, and the other conditions were the same as those in Example 1. The performance test results are shown in Table 2.

[0053] Example 9

[0054] The reverse osmosis membrane was prepared according to the procedure of Example 1, except that the m-phenylenediamine was replaced by 2,4-diaminotoluene, the trimesoyl chloride was replaced by isophthaloyl chloride, and the isopar G isomeric alkane was replaced by n-hexane, and the other conditions were the same as those in Example 1. The performance test results are shown in Table 2.

[0055] Comparative Example 1

[0056] Compared with Example 1, the difference is that no DBU post-treatment is performed.

[0057] S1: An aqueous solution with a mass fraction of 2.0 wt% m-phenylenediamine and an organic solution of isopar G isomeric alkane with a mass fraction of 0.1 wt% trimesoyl chloride were prepared; a porous polysulfone-based membrane was immersed in the aqueous solution at room temperature for 30 s, and the excess aqueous solution on the surface of the membrane was removed using a squeeze roller, then the organic solution was uniformly coated on the surface of the membrane, and the interfacial polymerization reaction was carried out at room temperature for 30 s, followed by pouring off the excess organic solution and blowing with a air knife until no solvent remained on the surface of the membrane.

[0058] S2: The reverse osmosis membrane obtained in S1 was immersed in pure water at 85°C for 60 s to obtain a polyamide reverse osmosis membrane. The performance test results are shown in Table 2.

[0059] Comparative Example 2

[0060] Compared with Example 9, the difference is that no DBU post-treatment is performed.

[0061] S1: prepare a water phase solution with 2.0wt% 2,4-diaminotoluene and a n-hexane organic phase solution with 0.1wt% isophthaloyl chloride; immerse the porous polysulfone base film in the water phase solution for 30s at room temperature, remove the excess water phase solution on the surface of the base film by using a squeeze roller, then evenly coat the organic phase solution on the surface of the film, stand for 30s at room temperature for interfacial polymerization, then pour off the excess organic phase solution and blow off by using a air knife until no solvent remains on the surface of the film.

[0062] S2: immerse the reverse osmosis membrane obtained in S1 in pure water at 85℃ for 60s to obtain a polyamide reverse osmosis membrane. The performance test results are shown in Table 2.

[0063] Table 2: membrane performance test data

[0064] Flux (LMH) Desalination rate (%) Example 1 109 99.0 Example 2 107 99.1 Example 3 105 99.2 Example 4 101 99.3 Example 5 108 99.1 Example 6 104 99.1 Example 7 95 99.3 Example 8 110 98.9 Example 9 110 98.6 Comparative Example 1 55 99.1 Comparative Example 2 60 98.5

[0065] From the experimental results in Table 2, it can be seen that compared with the comparative example which is not post-treated by DBU, the reverse osmosis membrane prepared in the examples has a significantly improved flux while maintaining a high desalination rate, showing excellent separation performance.

[0066] The above description is only the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method of making a high flux polyamide reverse osmosis membrane, characterized in that, The method comprises the following steps: S1: the porous support layer substrate film is contacted with an aqueous solution containing a multifunctional amine, and then contacted with an organic phase solution containing a multifunctional acyl chloride, to obtain a polyamide reverse osmosis membrane F1; S2: the F1 is immersed in an aqueous solution containing 1,8-diazabicyclo[5.4.0]undec-7-ene for treatment, to obtain a polyamide reverse osmosis membrane.

2. The method of claim 1, wherein, The multifunctional amine in S1 is an aromatic amine containing at least two primary amine groups.

3. The method of claim 2, wherein, The multifunctional amine in S1 is one or more of m-phenylenediamine, p-phenylenediamine, 2,4-diaminotoluene, and 2,6-diaminotoluene.

4. The method of claim 2, wherein, The concentration of the multifunctional amine in the aqueous solution is 1.0-10 wt%.

5. The method of claim 4, wherein, The concentration of the multifunctional amine in the aqueous solution is 2.0-5.0 wt%.

6. The method of claim 1, wherein, The multifunctional acyl chloride in S1 is an aromatic polyacyl chloride.

7. The method of claim 6, wherein, The multifunctional acyl chloride in S1 is one or more of trimesoyl chloride, isophthaloyl chloride, and naphthalene dicarboxylic chloride.

8. The method of claim 1, wherein, The concentration of the multifunctional acyl chloride in the organic phase solution is 0.01-1.0 wt%.

9. The method of claim 8, wherein, The concentration of the multifunctional acyl chloride in the organic phase solution is 0.1-0.25 wt%.

10. The method of claim 1, wherein, The solvent of the organic phase solution is one or more of n-hexane, Isopar G, and Isopar L.

11. The method of claim 1, wherein, The contact time of the porous support layer substrate film in S1 with the aqueous solution is 10-60 s, and the contact time with the organic phase solution containing the multifunctional acyl chloride is 10-60 s.

12. The method of claim 1, wherein, The porous support layer substrate film is selected from at least one of polysulfone, polyethersulfone, polyarylether, polyacrylonitrile, polyvinylidene fluoride, polytetrafluoroethylene, and polyaryletherketone.

13. The method of claim 1, wherein, The concentration of the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene in S2 is 1-20 wt%.

14. The method of claim 13, wherein, The concentration of the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene in S2 is 5-15 wt%.

15. The method of claim 1, wherein, The temperature of the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene in S2 is 0-90℃.

16. The method of claim 1, wherein, The temperature of the aqueous solution of 1,8-diazabicyclo[5.4.0]undec-7-ene in S2 is 25-50℃.

17. The method of claim 1, wherein, The immersion time in S2 is 30-300 s.

18. The method of claim 17, wherein, The immersion time in S2 is 60-120 s.

19. The method of claim 1, wherein, Further comprising a step S3: the polyamide reverse osmosis membrane obtained in step S2 is cleaned.

20. The method of claim 19, wherein, The polyamide reverse osmosis membrane obtained in step S2 is cleaned with pure water at a temperature of 70-90℃ for 60-300 s.

21. A high-flux polyamide reverse osmosis membrane prepared by the method of any one of claims 1-20.

22. Use of a high-flux polyamide reverse osmosis membrane prepared by the method of any one of claims 1-20 or the high-flux polyamide reverse osmosis membrane of claim 21 in the field of household water purifiers and industrial wastewater treatment.

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