Composite membrane material for sewage treatment and preparation method thereof

Abstract

The invention discloses a composite membrane material for sewage treatment and a preparation method thereof, and belongs to the technical field of sewage treatment, and the composite membrane material is prepared by loading three layers of different network polymers on the surface of a ceramic chip; the network-like polymer is prepared by performing esterification reaction on alpha-cyclodextrin, beta-cyclodextrin, gamma-cyclodextrin and 2, 2 '-[oxybis (ethylene glycol oxygen)] diacetyl chloride respectively; the composite membrane material for sewage treatment prepared by the invention has relatively strong adsorption performance, relatively high mechanical strength and stability, and has a good application prospect in the aspects of adsorption of refractory organic wastewater and treatment of heavy metals and ammonia nitrogen.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage treatment, and in particular relates to a composite membrane material for sewage treatment and a preparation method thereof. Background Art

[0002] Natural rivers are currently characterized by high chemical oxygen demand, high suspended solids, and high hardness. Furthermore, industrial wastewater discharge leads to an increase in organic pollutants in natural rivers. Therefore, wastewater treatment in natural rivers has become extremely important. Among the many wastewater treatment technologies, composite membrane materials, due to their high selectivity, high flux, and ease of integration, are key to solving water pollution problems. Currently, widely used single-layer composite membranes integrate multiple functional components and adsorption channels of varying sizes, enabling the simultaneous removal of multiple pollutants (such as heavy metals, organic matter, oils, and bacteria) from wastewater, thereby improving purification efficiency per unit area.

[0003] However, this "integrated" design has significant flaws: heterogeneous pores optimized for adsorbing different pollutants (macromolecules, ions, colloids, etc.) are tightly packed within the same membrane layer, causing pollutants to rapidly compete for limited adsorption sites and easily saturating the membrane. Furthermore, saturated pollutant particles accumulate on the membrane surface and in the narrow, crowded pores within, forming a dense filter cake layer and causing deep pore blockage. This compact structure makes it difficult to clear blockages once they occur, leading to a sharp drop in membrane flux and the need for frequent cleaning or replacement, which increases operating costs and shortens service life. Therefore, the preparation of a new composite membrane material is of great significance for improving wastewater treatment efficiency and extending the service life of the material. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a composite membrane material for sewage treatment and a preparation method thereof.

[0005] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions: A composite membrane material for sewage treatment is prepared according to the following method: three layers of different network polymers are loaded on the surface of a ceramic sheet; The network polymer is prepared by respectively carrying out esterification reaction between α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin and 2,2'-[oxybis(ethylene glycol oxygen)] diacetyl chloride.

[0006] The method for preparing the composite membrane material for sewage treatment comprises the following steps: 1) Add α-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, then add triethylamine, and stir to mix evenly to obtain a viscous mixture. The obtained viscous mixture is evenly coated on a ceramic sheet and allowed to stand for 24-48 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer; 2) adding β-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, and then adding triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1), and letting it stand for 24 to 48 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding γ-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, and then adding triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2), and letting it stand for 24 to 48 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 5 to 10 hours and then drying to obtain a composite membrane material for sewage treatment.

[0007] The organic solvent in step 1) is tetrahydrofuran, acetone, dimethylformamide or dimethyl sulfoxide.

[0008] The mass ratio of α-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine in step 1) is 1:1-1.8:1-2:0.8-1.5.

[0009] In step 2), the mass ratio of β-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine is 1:1.2-2:1-2:0.9-1.8.

[0010] In step 3), the mass ratio of γ-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine is 1:1.3-2.4:1-2:1-2.4.

[0011] The thickness of the film on the surface of the ceramic sheet loaded with the α-cyclodextrin network polymer in step 1) is 0.1-0.2 mm.

[0012] The thickness of the film on the surface of the ceramic sheet loaded with the β-cyclodextrin network polymer in step 2) is 0.1-0.2 mm.

[0013] The thickness of the film on the surface of the ceramic sheet loaded with the γ-cyclodextrin network polymer in step 3) is 0.1-0.2 mm.

[0014] Compared with the prior art, the present invention has the following advantages: The composite membrane material for sewage treatment of the present invention has a unique cavity structure of cyclodextrin that can wrap and adsorb organic pollutants, and can also be used as a microbial carrier to degrade ammonia nitrogen pollutants. It can also form complexes with heavy metal ions to adsorb and remove heavy metal ions. The ceramic sheet has a porous structure and has high mechanical strength and chemical stability, and can be used for sewage treatment. The present invention uses three cyclodextrins of different sizes (α, β and γ-cyclodextrin) as nodes of the polymerization reaction, and prepares a network polymer through esterification reaction with diacetyl chloride, and applies it to the surface of the ceramic sheet. After polymerization and curing, a porous film rich in cyclodextrin is formed on the surface of the ceramic sheet. Then, a network polymer obtained by the reaction of the second cyclodextrin and diacetyl chloride is applied, and cured to form a second layer of film. This step is repeated to finally prepare three layers of porous films rich in cyclodextrin. Its structural schematic diagram is shown as follows. Figure 1 As shown, each layer of film and ceramic sheet is tightly connected by a large number of hydrogen bonds. The network polymer increases the specific surface area of the material on the one hand, and on the other hand increases the adsorption sites and improves the adsorption efficiency.

[0015] The composite membrane material for sewage treatment of the present invention arranges multiple layers of thin films with different pore sizes and functional properties in an orderly layered manner to prepare a layered composite film, which overcomes the limitations of a single-layer film; the multi-layer film can be specifically optimized for pollutants in a specific size range, and the pollutants are intercepted and adsorbed step by step, avoiding disordered competition for adsorption sites among different pollutants in the same layer, improving the utilization rate of the material, and extending the service life of the material; in addition, the cyclodextrin side chain is a flexible ether chain, so there are interlayer gaps between the layers of the film, and these interlayer gaps provide buffer space, avoiding the problem of pore blockage caused by adsorption saturation of the single-layer membrane, and ensuring the stability of the material in use.

[0016] The composite membrane material for sewage treatment of the present invention has strong adsorption performance, high mechanical strength and stability, and has good application prospects in the adsorption of difficult-to-degrade organic wastewater, heavy metals and ammonia nitrogen treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the material of the present invention; In the figure, 1, ceramic sheet; 2, α-cyclodextrin film layer; 3, β-cyclodextrin film layer, 4, γ-cyclodextrin film layer. DETAILED DESCRIPTION

[0018] In order to better understand the technical solutions of the present invention, the following is a further detailed description of the above content of the present invention through specific implementation methods in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0019] Example 1 1) 1 kg of α-cyclodextrin and 1 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1 kg of tetrahydrofuran, and 0.8 kg of triethylamine was added, and the mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.1 mm and allowed to stand for 24 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 1.2 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1 kg of acetone, and then adding 0.9 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.1 mm, and letting it stand for 24 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 1.3 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1 kg of acetone, and then adding 1 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.1 mm, and letting it stand for 24 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 5 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0020] Example 2 1) 1 kg of α-cyclodextrin and 1.1 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.2 kg of acetone, and then 1 kg of triethylamine was added. The mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.12 mm and allowed to stand for 30 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 1.4 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.2 kg of acetone, and then adding 1 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.12 mm, and letting it stand for 30 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 1.5 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.2 kg of acetone, and then adding 1.4 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.12 mm, and letting it stand for 30 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 6 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0021] Example 3 1) 1 kg of α-cyclodextrin and 1.3 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.5 kg of dimethylformamide, and then 1.1 kg of triethylamine was added. The mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.15 mm and allowed to stand for 35 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 1.5 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.3 kg of dimethyl sulfoxide, and then adding 1.3 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.14 mm, and letting it stand for 35 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 1.8 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.2 kg of dimethyl sulfoxide, and then adding 1.8 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.15 mm, and letting it stand for 35 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 8 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0022] Example 4 1) 1 kg of α-cyclodextrin and 1.5 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.4 kg of dimethyl sulfoxide, and then 1.3 kg of triethylamine was added. The mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.18 mm and allowed to stand for 40 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 1.6 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.5 kg of tetrahydrofuran, and then adding 1.5 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.16 mm, and letting it stand for 40 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 2 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.2 kg of dimethyl sulfoxide, and then adding 2 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.17 mm, and letting it stand for 42 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 8 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0023] Example 5 1) 1 kg of α-cyclodextrin and 1.6 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.5 kg of acetone, and then 1.4 kg of triethylamine was added. The mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.19 mm and allowed to stand for 45 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 1.8 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.8 kg of dimethyl sulfoxide, and then adding 1.6 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.12 mm, and letting it stand for 46 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 2.2 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.5 kg of acetone, and then adding 2.2 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.19 mm, and letting it stand for 46 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 9 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0024] Example 6 1) 1 kg of α-cyclodextrin and 1.8 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 2 kg of tetrahydrofuran, and then 1.5 kg of triethylamine was added. The mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.2 mm and allowed to stand for 48 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of β-cyclodextrin and 2 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 2 kg of tetrahydrofuran, and then adding 2 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.2 mm, and letting it stand for 48 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding 1 kg of γ-cyclodextrin and 2.4 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 2 kg of tetrahydrofuran, and then adding 2.4 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2) to a coating thickness of 0.2 mm, and letting it stand for 48 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 10 hours and then drying it to obtain a composite membrane material for sewage treatment. Comparative Example 1: 1 kg of γ-cyclodextrin and 1.8 kg of 2,2'-[oxybis(ethylene glycoloxy)]diacetyl chloride were added to 1.2 kg of dimethyl sulfoxide, and then 1.8 kg of triethylamine was added, and the mixture was stirred and mixed evenly to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet with a coating thickness of 0.15 mm and allowed to stand for 35 hours to obtain a ceramic sheet with a surface loaded with a γ-cyclodextrin network polymer; the prepared ceramic sheet with a surface loaded with a γ-cyclodextrin network polymer was soaked in water for 8 hours and then dried to obtain a composite membrane material for sewage treatment.

[0025] Comparative Example 2 1) 1 kg of α-cyclodextrin and 1.3 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.5 kg of dimethylformamide, and then 1.1 kg of triethylamine was added, and the mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.15 mm and allowed to stand for 35 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer; 2) adding 1 kg of β-cyclodextrin and 1.5 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.3 kg of dimethyl sulfoxide, and then adding 1.3 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.14 mm, and letting it stand for 35 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded β-cyclodextrin network polymer prepared in step 2) in water for 8 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0026] Comparative Example 3 1) 1 kg of α-cyclodextrin and 1.3 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride were added to 1.5 kg of dimethylformamide, and then 1.1 kg of triethylamine was added, and the mixture was stirred and mixed to obtain a viscous mixture. The obtained viscous mixture was evenly coated on a ceramic sheet to a thickness of 0.15 mm and allowed to stand for 35 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer. 2) adding 1 kg of α-cyclodextrin and 1.5 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.3 kg of dimethyl sulfoxide, and then adding 1.3 kg of triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1) to a coating thickness of 0.14 mm, and letting it stand for 35 hours to obtain a ceramic sheet with two layers of α-cyclodextrin network polymer loaded on the surface; 3) Add 1 kg of α-cyclodextrin and 1.8 kg of 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to 1.2 kg of dimethyl sulfoxide, and then add 1.8 kg of triethylamine, and stir to mix uniformly to obtain a viscous mixture. The obtained viscous mixture is evenly coated on the ceramic sheet with two layers of α-cyclodextrin network polymer on the surface obtained in step 2) to a coating thickness of 0.15 mm. The ceramic sheet is allowed to stand for 35 hours to obtain a ceramic sheet with three layers of α-cyclodextrin network polymer on the surface; 4) Soaking the ceramic sheet with the three-layer α-cyclodextrin network polymer loaded on its surface prepared in step 3) in water for 8 hours and then drying it to obtain a composite membrane material for sewage treatment.

[0027] The composite membrane materials for sewage treatment prepared in Examples 1 to 6 of the present invention and Comparative Examples 1 to 3 were placed in a treatment tank, where the initial concentrations of phenol, benzo[a]pyrene, and naphthalene in the treatment tank were all 20 ppm. After 3 hours, the concentrations of each pollutant in the tank were measured, and the adsorption efficiency was calculated. The test results are shown in Table 1. As shown in Table 1, the composite membrane materials for sewage treatment prepared in the present invention have higher adsorption efficiency than the comparative examples.

[0028] Table 1 Adsorption efficiency of materials prepared in Examples and Comparative Examples (%)

[0029] The composite membrane materials for sewage treatment prepared in Examples 1 to 6 of the present invention and Comparative Examples 1 to 3 were respectively used to treat electroplating sewage, and the treatment results are shown in Table 2. As can be seen from the results in Table 2, the composite membrane materials for sewage treatment prepared in the present invention have greater adsorption efficiency and better adsorption effect on heavy metals than the comparative examples, and the electroplating sewage treated with the composite membrane materials for sewage treatment can meet the discharge standards.

[0030] Table 2 Treatment results of electroplating wastewater by materials prepared in Examples and Comparative Examples

[0031] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A composite membrane material for sewage treatment, characterized in that: The preparation method is as follows: three layers of different network polymers are loaded on the surface of the ceramic sheet; The network polymer is prepared by respectively carrying out esterification reaction between α-cyclodextrin, β-cyclodextrin and γ-cyclodextrin and 2,2'-[oxybis(ethylene glycol oxygen)] diacetyl chloride.

2. The method for preparing the composite membrane material for sewage treatment according to claim 1, characterized in that: The following steps are involved: 1) Add α-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, then add triethylamine, and stir to mix evenly to obtain a viscous mixture. The obtained viscous mixture is evenly coated on a ceramic sheet and allowed to stand for 24-48 hours to obtain a ceramic sheet with a surface-loaded α-cyclodextrin network polymer; 2) adding β-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, and then adding triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded α-cyclodextrin network polymer obtained in step 1), and letting it stand for 24 to 48 hours to obtain a ceramic sheet with the surface-loaded β-cyclodextrin network polymer; 3) adding γ-cyclodextrin and 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride to an organic solvent, and then adding triethylamine, stirring and mixing to obtain a viscous mixture, and evenly coating the obtained viscous mixture on the ceramic sheet with the surface-loaded β-cyclodextrin network polymer obtained in step 2), and letting it stand for 24 to 48 hours to obtain a ceramic sheet with the surface-loaded γ-cyclodextrin network polymer; 4) Soaking the ceramic sheet with the surface-loaded γ-cyclodextrin network polymer prepared in step 3) in water for 5 to 10 hours and then drying to obtain a composite membrane material for sewage treatment.

3. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: The organic solvent in step 1) is tetrahydrofuran, acetone, dimethylformamide or dimethyl sulfoxide.

4. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: The mass ratio of α-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine in step 1) is 1:1-1.8:1-2:0.8-1.

5.

5. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: In step 2), the mass ratio of β-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine is 1:1.2-2:1-2:0.9-1.

8.

6. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: In step 3), the mass ratio of γ-cyclodextrin, 2,2'-[oxybis(ethylene glycoloxy)] diacetyl chloride, organic solvent and triethylamine is 1:1.3-2.4:1-2:1-2.

4.

7. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: The thickness of the film on the surface of the ceramic sheet loaded with the α-cyclodextrin network polymer in step 1) is 0.1-0.2 mm.

8. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: The thickness of the film on the surface of the ceramic sheet loaded with the β-cyclodextrin network polymer in step 2) is 0.1-0.2 mm.

9. The method for preparing a composite membrane material for sewage treatment according to claim 2, wherein: The thickness of the film on the surface of the ceramic sheet loaded with the γ-cyclodextrin network polymer in step 3) is 0.1-0.2 mm.

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