Flat ceramic nanofiltration membrane for water purification and preparation method of flat ceramic nanofiltration membrane

Abstract

The invention relates to the technical field of filtering membrane materials, in particular to a flat ceramic nanofiltration membrane for water purification and a preparation method of the flat ceramic nanofiltration membrane. The method comprises the following steps: S1, putting a flat plate ceramic membrane support body into dichloromethane containing an amino silane coupling agent, and reacting to obtain an amino-modified flat plate ceramic membrane A; s2, mixing phenolic resin microspheres with graphene oxide to prepare a functional dispersion liquid B; and S3, adding the functional dispersion liquid B into a vacuum suction filtration device with a flat ceramic membrane A, reacting, performing vacuum suction filtration, and drying to obtain the flat ceramic nanofiltration membrane. The graphene oxide (2D) and the phenolic resin (0D) form a heterojunction structure, and the pi-pi interaction of the heterojunction structure promotes the capability of generating H2O2 under illumination, so that in-situ sterilization and purification of water can be realized, organic pollutants can be degraded, and the anti-pollution performance of the membrane can be improved; meanwhile, the layered structure of the graphene oxide ensures that the water flux of the ceramic membrane is not influenced, and meanwhile, the filtering precision of the membrane is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of filtration membrane materials, and in particular to a flat ceramic nanofiltration membrane for water purification and a preparation method thereof. Background Art

[0002] As water pollution becomes more serious, the development of efficient and long-lasting water purification membrane technology has become an urgent need. Although traditional ceramic nanofiltration membranes have advantages such as high chemical stability, high temperature resistance, and strong mechanical strength, they have the following technical bottlenecks:

[0003] ① Insufficient anti-pollution performance: Natural organic matter (such as humic acid), microorganisms and inorganic salts are easily adsorbed or deposited on the membrane surface, resulting in clogging of membrane pores and significant attenuation of water flux;

[0004] ② The sterilization function relies on external processes: sterilization requires ultraviolet radiation or chlorine disinfection and other steps, and it is impossible to simultaneously complete water purification and microbial inactivation in situ;

[0005] ③ Conflict between filtration accuracy and water flux: Improving filtration accuracy (such as reducing membrane pore size) usually comes at the expense of water flux, making it difficult to meet the needs of efficient water purification.

[0006] Although existing improvement solutions (such as surface coating of nano-photocatalyst TiO2) can degrade pollutants through photocatalytic reactions, they have problems such as low quantum efficiency, the need for additional electron donors, and easy agglomeration and deactivation. In addition, the photocatalytic process may destroy the integrity of the membrane structure.

[0007] Therefore, it is necessary to provide a ceramic flat nanofiltration membrane for water purification to solve the problems raised in the above background technology. Summary of the Invention

[0008] The main purpose of the present invention is to provide a flat ceramic nanofiltration membrane for water purification and a preparation method thereof to solve the above technical problems.

[0009] To achieve the above object, the present invention provides a method for preparing a flat ceramic nanofiltration membrane, comprising the steps of:

[0010] S1: providing an aluminum oxide-based flat ceramic membrane support, and placing the flat ceramic membrane support in dichloromethane containing an aminosilane coupling agent, reacting at room temperature for 42-54 hours, and then taking it out to obtain an amino-modified flat ceramic membrane A;

[0011] S2, mixing phenolic resin microspheres and graphene oxide in a ratio of 1:0.1 to 10 to prepare a functional dispersion B;

[0012] S3: Add the functional dispersion B into a vacuum filtration device containing the flat ceramic membrane A, react for 0.5-3 hours, and then vacuum filter. Then, dry the flat ceramic membrane A to obtain a flat ceramic nanofiltration membrane.

[0013] Preferably, the method comprises: boiling the flat ceramic membrane support in water for more than 0.5 h, then placing it in dichloromethane containing an aminosilane coupling agent, reacting at room temperature for 46-50 h, and then taking it out to obtain an amino-modified flat ceramic membrane A.

[0014] Preferably, the step S1 further comprises: sealing one side of the flat ceramic membrane support body with tape, and then placing the support body in dichloromethane containing an aminosilane coupling agent for reaction.

[0015] Preferably, the silane coupling agent is selected from at least one of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane.

[0016] Preferably, the reaction temperature of placing the flat ceramic membrane support in dichloromethane containing an aminosilane coupling agent is 180-250° C., and the reaction time is 10-30 min.

[0017] Preferably, in step S2, the graphene oxide is a single-layer graphene oxide.

[0018] Preferably, the step S2 includes: mixing phenolic resin microspheres and graphene oxide in a ratio of 1:0.1 to 10 with a reaction solution, and then ultrasonically dispersing for 0.5-2 hours to prepare a functional dispersion B.

[0019] Preferably, in step S2, the activated aqueous solution is a mixed solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) / N-hydroxysuccinimide (NHS).

[0020] The present invention also provides a flat ceramic nanofiltration membrane, which is prepared by any of the preparation methods described above.

[0021] The present invention also provides an application of the above-mentioned flat ceramic nanofiltration membrane in water purification.

[0022] In the present invention, the amino groups on the surface of the amino-modified flat ceramic membrane A of the modified flat ceramic membrane support form chemical bonds with the carboxyl hydroxyl groups on the graphene surface or the hydroxyl groups of the phenolic resin microspheres, and the carboxyl groups of the graphene oxide are activated by EDC / NHS to undergo amidation reaction with the surface of the amino-modified ceramic membrane, so that the catalyst is not easily peeled off from the membrane surface, thereby solving the problem of the catalyst's adhesion on the ceramic membrane surface; by utilizing the layered structure of the graphene oxide and the spherical structure of the phenolic resin, the 2D layered structure of the graphene oxide can obtain a highly ordered layered structure during the filtration process to improve the membrane Mechanical strength; Phenolic resin is a 0D polymer, and its benzene ring structure can form a strong interaction with graphene oxide through π-π stacking to construct a three-dimensional heterojunction structure, forming a 2D / 0D heterojunction structure, which can improve the interception accuracy while retaining a large pure water flux; This heterojunction can significantly inhibit the recombination of photogenerated electrons and holes, prolong the charge life, and thus efficiently produce H2O2 under light (quantum efficiency increased by 3-5 times). The H2O2 produced by phenolic resin under light irradiation can be used to achieve in situ sterilization and degradation of organic pollutants, which can reduce the pollution performance of the membrane during use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an undue limitation of the present invention. Obviously, the drawings described below are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive effort. In the accompanying drawings:

[0024] Figure 1 Schematic diagram of the preparation process of the flat ceramic nanofiltration membrane in the present invention.

[0025] Figure 2 This is a scanning electron microscope image of the surface morphology of graphene oxide / phenolic resin on the surface of the flat ceramic nanofiltration membrane prepared in Example 1.

[0026] Figure 3 This is a photo of the appearance of the flat ceramic nanofiltration membrane prepared in Example 1.

[0027] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical problems solved by the embodiments of the present invention, the technical solutions adopted, and the technical effects achieved, in conjunction with the accompanying drawings and specific embodiments. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other equivalent or obviously modified embodiments obtained by ordinary technicians in this field without paying creative work fall within the scope of protection of the present invention. The embodiments of the present invention can be concretized in a variety of different ways as defined and covered in the claims.

[0029] It should be noted that in the following description, many specific details are given for ease of understanding, but it is obvious that the present invention can be implemented without these specific details.

[0030] It should be noted that, in the absence of clear limitations or conflicts, the various embodiments of the present invention and the technical features therein can be combined with each other to form a technical solution.

[0031] Example 1:

[0032] This embodiment 1 provides a method for preparing a flat ceramic nanofiltration membrane, comprising the following steps:

[0033] An aluminum oxide-based flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration apparatus containing the amino-modified flat ceramic membrane A. The mixture was allowed to react for 1 hour, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0034] Example 2:

[0035] This embodiment 2 provides a method for preparing a flat ceramic nanofiltration membrane, comprising the following steps:

[0036] The flat ceramic membrane was boiled in deionized water for 1 hour and dried in a 105°C oven for 2 hours. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to form solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to form solution B2. Solutions B1 and B2 were mixed and placed in a vacuum filtration apparatus equipped with a flat ceramic membrane. The mixture was allowed to react for 1 hour, filtered, and dried at 60°C for 4 hours.

[0037] Example 3:

[0038] This embodiment 3 provides a method for preparing a plate ceramic nanofiltration membrane for water purification, comprising the following steps:

[0039] The flat ceramic membrane support was boiled in deionized water for 1 hour and dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in a 0.5% 3-aminopropyltriethoxysilane solution in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed to obtain a flat ceramic membrane A with amino groups modified in the membrane separation layer. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. Solution B1 was placed in a vacuum filtration apparatus containing the amino-modified flat ceramic membrane A, reacted for 1 hour, filtered, and dried at 60°C for 4 hours.

[0040] Example 4:

[0041] This embodiment 4 provides a method for preparing a flat ceramic nanofiltration membrane, comprising the following steps:

[0042] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane was removed to obtain amino-modified flat ceramic membrane A in a membrane separation layer machine. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water, and high-speed spherical ink was added for 10 seconds to obtain solution B2. Solution B2 was placed in a vacuum filtration device containing amino-modified flat ceramic membrane A, reacted for 1 hour, filtered, and dried at 60°C for 4 hours.

[0043] Example 5

[0044] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 0.5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The mixture was reacted for 1 hour, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0045] Example 6

[0046] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 5 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The mixture was reacted for 1 hour, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0047] Example 7

[0048] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.3% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The mixture was reacted for 1 hour, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0049] Example 8

[0050] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The mixture was reacted for 0.5 hours, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0051] Example 9

[0052] The flat ceramic membrane support was placed in deionized water and boiled for 1 hour, then dried in a 105°C oven for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% 3-aminopropyltriethoxysilane in dichloromethane. After reacting at room temperature for 48 hours, the membrane separation layer was removed and an amino-modified flat ceramic membrane A was obtained. 1 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to obtain solution B1. 5 mg of phenolic resin microspheres were weighed and dissolved in 1 mL of water and high-speed graphitization was performed for 10 seconds to obtain solution B2. The B1 and B2 solutions were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The mixture was reacted for 10 minutes, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0053] Test method: The pure water flux, the retention rate of BSA bovine serum albumin (0.1 g / L) and the flux recovery rate of the membrane were tested at a transmembrane pressure difference of 0.4 MPa and a temperature of (25±2)°C.

[0054] The pure water flux, retention of bovine serum albumin (BSA) and flux recovery rate of the samples obtained in Examples 1-4 are shown in Table 1:

[0055] Table 1 Test results of samples obtained in Examples 1-4

[0056] Pure water flux (LMH) Retention rate (%) Flux recovery rate (%) Example 1 36 99.9 98.5 Example 2 34 99.4 95.2 Example 3 28 99.9 97.5 Example 4 42 84 80.1 Example 5 31 99.5 90.7 Example 6 25 99.9 98.9 Example 7 35 98.4 95.6 Example 8 35 99.1 96.2 Example 9 36 98.7 95.6

[0057] Please refer to Figure 1 , is a scanning electron micrograph of the surface morphology of graphene oxide / phenolic resin on the surface of the flat ceramic nanofiltration membrane prepared in Example 1; Figure 2 This is a photo of the appearance of the flat ceramic nanofiltration membrane prepared in Example 1.

[0058] As shown in Table 1, orderly stacking of graphene oxide on a ceramic membrane improves pure water flux recovery, but the pure water flux is relatively low. Forming a heterojunction multilayer structure with phenolic resin achieves the highest pure water flux while maintaining high rejection. This is because the staggered layered structure of graphene oxide facilitates the flow of water molecules, while the spherical structure of phenolic resin increases the interlayer spacing of graphene oxide, thereby improving pure water flux. Under visible light irradiation, the π-π structure of graphene oxide and phenolic resin promotes the two-electron reduction of O2 to produce H2O2, which oxidatively degrades bovine serum albumin on the membrane surface and improves the membrane's flux recovery. The silane coupling agent content and the duration of amination on the membrane surface affect the adhesion of the catalytic layer, which in turn influences membrane retention and flux recovery.

[0059] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. A method for preparing a flat ceramic nanofiltration membrane, characterized in that: Including steps: S1: providing an aluminum oxide-based flat ceramic membrane support, and placing the flat ceramic membrane support in dichloromethane containing an aminosilane coupling agent, reacting at room temperature for 42-54 hours, and then taking it out to obtain an amino-modified flat ceramic membrane A; S2, mixing phenolic resin microspheres and graphene oxide in a ratio of 1:0.1 to 10 to prepare a functional dispersion B; S3: Add the functional dispersion B into a vacuum filtration device containing the flat ceramic membrane A, react for 0.5-3 hours, and then vacuum filter. Then, dry the flat ceramic membrane A to obtain a flat ceramic nanofiltration membrane.

2. The method for preparing a flat ceramic nanofiltration membrane according to claim 1, wherein: The step S1 includes: boiling the flat ceramic membrane support in water for more than 0.5 hours, then placing it in dichloromethane containing an aminosilane coupling agent, reacting at room temperature for 46-50 hours, and then taking it out to obtain an amino-modified flat ceramic membrane A.

3. The method for preparing a flat ceramic nanofiltration membrane according to claim 2, wherein: The step S1 further includes: sealing one side of the flat ceramic membrane support body with tape, and then placing the support body in dichloromethane containing an aminosilane coupling agent for reaction.

4. The method for preparing a flat ceramic nanofiltration membrane according to any one of claims 1 to 3, characterized in that: The silane coupling agent is selected from at least one of N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane; wherein the content of the aminosilane coupling agent is 0.3-0.8%.

5. The method for preparing a flat ceramic nanofiltration membrane according to any one of claims 1 to 3, characterized in that: The flat ceramic membrane support is placed in dichloromethane containing an aminosilane coupling agent at a reaction temperature of 180-250° C. and a reaction time of 10-30 minutes.

6. The method for preparing a flat ceramic nanofiltration membrane according to claim 1, wherein: In step S2, the graphene oxide is a single-layer graphene oxide with a sheet diameter of 3-8 μm.

7. The method for preparing a flat ceramic nanofiltration membrane according to claim 1, wherein: The step S2 includes: mixing phenolic resin microspheres and graphene oxide in a ratio of 1:0.1-2 with an activated aqueous solution, and then ultrasonically dispersing for 0.5-2 hours to prepare a functional dispersion B.

8. The method for preparing a flat ceramic nanofiltration membrane according to claim 7, wherein: In step S2, the activated aqueous solution is a mixed MES buffer solution of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC / N-hydroxysuccinimide NHS in a mass ratio of 1:

1.

9. A flat ceramic nanofiltration membrane, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. Use of the flat ceramic nanofiltration membrane according to claim 9 in water purification.

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