Flat ceramic nanofiltration membrane for purifying water and preparation method thereof

Abstract

The application relates to the technical field of filter membrane materials, in particular to a flat plate ceramic nanofiltration membrane for water purification and a preparation method thereof. The method comprises the following steps: S1, placing a flat plate ceramic membrane support in dichloromethane containing an amino silane coupling agent to obtain an amino-modified flat plate ceramic membrane A after reaction; S2, mixing phenolic resin microspheres with graphene oxide to prepare a functional dispersion liquid B; S3, adding the functional dispersion liquid B into a vacuum filtration device in which the flat plate ceramic membrane A is placed, performing reaction, vacuum filtration, drying, and obtaining a flat plate ceramic nanofiltration membrane. The heterojunction structure formed by graphene oxide (2D) and phenolic resin (0D) promotes the ability of the heterojunction to generate H2O2 under light, can in-situ sterilize and purify water, degrades organic pollutants, and improves the anti-pollution performance of the membrane; meanwhile, the layered structure of the graphene oxide ensures that the water flux of the ceramic membrane is not affected and improves the filtering precision of the membrane.

Description

Technical Field

[0001] This invention relates to the field of filter membrane material technology, and in particular to a flat-plate ceramic nanofiltration membrane for water purification and its preparation method. Background Technology

[0002] With the escalation of water pollution, the development of efficient and long-lasting water purification membrane technologies has become an urgent need. While traditional ceramic nanofiltration membranes possess advantages such as high chemical stability, high temperature resistance, and high mechanical strength, they also face the following technical bottlenecks:

[0003] ① Insufficient antifouling performance: Natural organic matter (such as humic acid), microorganisms and inorganic salts are easily adsorbed or deposited on the membrane surface, leading to membrane pore blockage and significant water flux reduction;

[0004] ② Sterilization function depends on external processes: It requires steps such as ultraviolet radiation or chlorine disinfection to achieve sterilization, and cannot 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 cost of water flux, making it difficult to meet the needs of high-efficiency water purification.

[0006] Existing improved solutions (such as surface-coated TiO2 nanocatalysts) can degrade pollutants through photocatalytic reactions, but they have problems such as low quantum efficiency, the need for additional electron donors, easy aggregation and deactivation, and the photocatalytic process may damage the integrity of the membrane structure.

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

[0008] The main objective of this invention is to provide a flat-plate ceramic nanofiltration membrane for water purification and its preparation method, so as to solve the above-mentioned technical problems.

[0009] To achieve the above objectives, the present invention provides a method for preparing a flat-panel ceramic nanofiltration membrane, comprising the following steps:

[0010] S1: Provide an alumina-based flat ceramic membrane support, and place the flat ceramic membrane support in dichloromethane containing an aminosilane coupling agent. After reacting at room temperature for 42-54 hours, remove the support to obtain an amino-modified flat ceramic membrane A.

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

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

[0013] Preferably, the method 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 removing it to obtain an amino-modified flat ceramic membrane A.

[0014] Preferably, step S1 further includes: sealing one side of the flat ceramic membrane support with tape, and then placing it 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 the flat ceramic membrane support placed in dichloromethane containing an aminosilane coupling agent is 180-250℃, and the reaction time is 10-30 min.

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

[0018] Preferably, step S2 includes: mixing phenolic resin microspheres and graphene oxide in a ratio of 1:0.1 to 10 with an aqueous solution, and then ultrasonically dispersing the mixture for 0.5 to 2 hours to obtain 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) and N-hydroxysuccinimide (NHS).

[0020] The present invention also provides a flat-panel ceramic nanofiltration membrane, which is prepared by the preparation method described in any of the preceding claims.

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

[0022] In this 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 surface of graphene or the hydroxyl groups of phenolic resin microspheres. The carboxyl groups of graphene oxide undergo an amidation reaction with the amino-modified ceramic membrane surface under EDC / NHS activation, making the catalyst less prone to peeling off from the membrane surface and solving the problem of catalyst adhesion on the ceramic membrane surface. Utilizing the layered structure of graphene oxide and the spherical structure of phenolic resin, the 2D layered structure of graphene oxide can achieve a highly ordered layered structure during the filtration process, thereby improving the membrane... The mechanical strength of the membrane is improved. Phenolic resin is an 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. This structure can improve the retention accuracy while retaining a large pure water flux. The heterojunction can significantly inhibit photogenerated electron-hole recombination and prolong charge lifetime, thereby efficiently generating H2O2 under light irradiation (quantum efficiency improved by 3-5 times). The H2O2 generated by phenolic resin under light irradiation can be used to achieve in-situ sterilization and degradation of organic pollutants, which can reduce the fouling performance of the membrane during use. Attached Figure Description

[0023] The accompanying drawings, as part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation of the invention. Obviously, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without creative effort. In the drawings:

[0024] Figure 1 This is a schematic diagram of the preparation process of the flat ceramic nanofiltration membrane in this 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 photograph of the appearance of the flat ceramic nanofiltration membrane prepared in Example 1.

[0027] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0028] The technical problems solved by the embodiments of the present invention, the technical solutions adopted, and the technical effects achieved will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other equivalent or obvious variations of embodiments obtained by those skilled in the art without creative effort fall within the protection scope of the present invention. The embodiments of the present invention can be embodied in various different ways as defined and covered by the claims.

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

[0030] It should be noted that, in the absence of explicit limitations or conflicts, the various embodiments and their technical features in this invention 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-panel ceramic nanofiltration membrane, comprising the following steps:

[0033] An alumina-based flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, the membrane was removed to obtain a flat ceramic membrane A with amino-modified 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. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to obtain solution B2. Solutions B1 and B2 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.

[0034] Example 2:

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

[0036] The flat ceramic membrane was boiled in deionized water for 1 hour and dried in an oven at 105°C 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 make solution B1. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 were mixed and placed in a vacuum filtration device containing the flat ceramic membrane. The mixture was reacted 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, including the following steps:

[0039] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in dichloromethane containing 0.5% 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, the membrane was removed to obtain a flat ceramic membrane A with amino-modified 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 make solution B1. Solution B1 was placed in a vacuum filter containing the amino-modified flat ceramic membrane A and reacted for 1 hour. After filtration, the membrane was dried at 60°C for 4 hours.

[0040] Example 4:

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

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

[0043] Example 5

[0044] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, it was removed to obtain a flat ceramic membrane A with amino-modified 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 make solution B1. 0.5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 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] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, it was removed to obtain a flat ceramic membrane A with amino-modified membrane separation layer. 5 mg of monolayer graphene oxide was dispersed in 1 mL of water, and 1 mL of EDC / NHS solution was added to make solution B1. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 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] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.3% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, it was removed to obtain a flat ceramic membrane A with amino-modified 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 make solution B1. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 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] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, it was removed to obtain a flat ceramic membrane A with amino-modified 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 make solution B1. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The reaction was carried out for 0.5 hours, filtered, and dried at 60°C for 4 hours to obtain a flat ceramic nanofiltration membrane.

[0051] Example 9

[0052] A flat ceramic membrane support was boiled in deionized water for 1 hour and dried in an oven at 105°C for 2 hours. One side of the flat ceramic membrane support was sealed with tape and then placed in 0.5% dichloromethane of 3-aminopropyltriethoxysilane. After reacting at room temperature for 48 hours, it was removed to obtain a flat ceramic membrane A with amino-modified 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 make solution B1. 5 mg of phenolic resin microspheres were weighed into 1 mL of water and subjected to high-speed ball milling for 10 seconds to make solution B2. Solutions B1 and B2 were mixed and placed in a vacuum filtration device containing the amino-modified flat ceramic membrane A. The reaction was carried out 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 rejection 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) ℃.

[0054] The pure water flux, bovine serum albumin (BSA) rejection, 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 The image shown 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. Figure 2 This is a photograph of the appearance of the flat ceramic nanofiltration membrane prepared in Example 1.

[0058] Table 1 shows that the ordered stacking of graphene oxide on the ceramic membrane improves the pure water flux recovery rate, but the pure water flux remains low. After forming a heterojunction multilayer structure with phenolic resin, the pure water flux remains the highest while maintaining a high rejection rate. 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, thus improving the 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 can oxidize and degrade bovine serum albumin on the membrane surface, improving the membrane flux recovery rate. The silane coupling agent content and the amination time on the membrane surface affect the adhesion of the catalyst layer, thereby affecting the membrane rejection and flux recovery.

[0059] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A method for preparing a flat-panel ceramic nanofiltration membrane, characterized in that, Including the following steps: S1: Provide an alumina-based flat ceramic membrane support, and place the flat ceramic membrane support in dichloromethane containing an aminosilane coupling agent. After reacting at room temperature for 42-54 h, remove the support to obtain an amino-modified flat ceramic membrane A. S2, Phenolic resin microspheres and graphene oxide are mixed with an activated aqueous solution at a mass ratio of 1:0.1~2 and then ultrasonically dispersed for 0.5-2 hours to obtain functional dispersion B; The activated aqueous solution is a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC / N-hydroxysuccinimide NHS mixed MES buffer at a mass ratio of 1:

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

2. The method for preparing a flat-plate ceramic nanofiltration membrane according to claim 1, characterized in that, 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 removing it to obtain an amino-modified flat ceramic membrane A.

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

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

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

6. A flat-plate ceramic nanofiltration membrane, characterized in that, It is prepared by any one of the preparation methods described in claims 1-5.

7. The application of the flat-plate ceramic nanofiltration membrane according to claim 6 in water purification.

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