A multi-stage porous supramolecular composite filter membrane, a preparation method and application thereof

Abstract

The application belongs to the technical field of environmental functional materials, and discloses a multistage porous supramolecular composite filter membrane, a preparation method and application. The preparation method comprises the following steps: S1, immersing a support membrane into a first raw material solution to obtain a material coating; S2, immersing the material coating into a second raw material solution to obtain a filter membrane coated with a first layer of supramolecular material; S3, immersing the filter membrane coated with the first layer of supramolecular material into the first raw material solution, repeating steps S1-S2 multiple times, and vacuum drying to obtain a multistage porous supramolecular composite filter membrane. The preparation conditions are mild, the filter membrane is stable in a water environment, has strong permeability to water and sodium chloride, and can selectively remove organic impurities.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, and more specifically, relates to a multi-level porous supramolecular composite filter membrane, its preparation method, and its application. Background Technology

[0002] With the continuous development of national industry, the organic chlorination process generates a large amount of sodium chloride byproducts containing organic impurities, which has seriously impacted the environment. Simultaneously, environmental policies and regulations are constantly being updated, with increasingly stringent requirements for these sodium chloride byproducts containing organic impurities. Inefficient recovery of sodium chloride slag not only negatively impacts resource recycling but also hinders environmental protection efforts. Therefore, recycling sodium chloride byproducts would significantly reduce operating and environmental remediation costs. The main impurities in sodium chloride byproducts are the various organic residues remaining after the reaction. To meet the quality requirements of sodium chloride for ion-exchange membrane caustic soda production, it is necessary to substantially eliminate organic impurities in sodium chloride byproducts, controlling their content below 10 PPM, and the inorganic ammonia content below 5 PPM.

[0003] Currently, the following methods for treating sodium chloride byproducts are reported in the available literature: The first is the salt washing method, which uses only water and detergents to remove organic impurities and other components from the salt. This method is only suitable for waste salt residue with a simple composition and low impurity content. The second is the high-temperature treatment method, which uses high-temperature gas to calcine the salt residue powder, decomposing the impurities in the salt into gases. These gases are then treated through various processes to achieve the purpose of treating the salt residue byproducts. However, this process often encounters problems, leading to salt agglomeration, equipment wear, and equipment corrosion at high temperatures. The third method is the high-temperature carbonization method, which carbonizes and decomposes the waste salt residue at high temperatures, causing some of the organic impurities and other impurities in the waste salt residue to decompose into volatile gases, while the rest cokes into organic carbon. However, this process has some problems, such as difficulty in controlling the carbonization temperature and the softening of the salt residue surface, which easily leads to clumping and affects continuous processing. Furthermore, the TOC and other impurity content in the treated sodium chloride residue is difficult to meet the quality requirements for sodium chloride raw materials for ion-exchange membrane caustic soda.

[0004] Therefore, there is an urgent need to develop a multi-level porous supramolecular composite filter membrane that can be used to remove organic impurities from sodium chloride byproducts produced in chemical production, so that sodium chloride solution can meet the requirements of ion-exchange membrane caustic soda industry. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a multi-level porous supramolecular composite filter membrane, its preparation method, and its applications. The preparation conditions of this invention are mild, the filter membrane is stable in an aqueous environment, exhibits strong permeability to water and sodium chloride, and can selectively remove organic impurities.

[0006] To achieve the above objectives, the first aspect of the present invention provides a method for preparing a multi-level porous supramolecular composite filter membrane, the method comprising the following steps:

[0007] S1: Immerse the support membrane in the first raw material solution to obtain a material coating;

[0008] S2: Immerse the material coating into the second raw material solution to obtain a filter membrane coated with the first layer of supramolecular material;

[0009] S3: Immerse the first layer of supramolecular material filter membrane into the first raw material solution, repeat steps S1-S2 multiple times, and vacuum dry to obtain the multi-level porous supramolecular composite material filter membrane.

[0010] According to the present invention, preferably, the support membrane is a cellulose membrane or a glass fiber membrane.

[0011] According to the present invention, preferably, the first raw material solution and the second raw material solution each independently comprise the following components: raw material, water and acidic catalyst.

[0012] According to the present invention, preferably, the raw material is 1,3,5-tris(4-aminophenyl)benzene, trialdehyde phloroglucinol, 5'-(4-formyl-3-hydroxyphenyl)-3,3”-dihydroxy-[1,1':3',1”-terphenyl]-4,4”-dicarboxaldehyde, 2,5-dimethoxy-p-phenylenedialdehyde, or biphenyl diamine.

[0013] According to the present invention, preferably, the concentration of the raw material in the first raw material solution and the second raw material solution is independently 0.8-1.2 mg / mL.

[0014] According to the present invention, preferably, the acidic catalyst is at least one selected from formic acid, acetic acid and hydrochloric acid.

[0015] According to the present invention, preferably, the concentration of the acidic catalyst in the first raw material solution and the second raw material solution is independently 0.01-0.15 mol / L.

[0016] According to the present invention, preferably, in step S1, the support film is immersed in the first raw material solution at 20-30°C for 30-80 minutes to obtain a material coating.

[0017] According to the present invention, preferably, in step S2, the material coating is immersed in the second raw material solution at 20-30°C for 5-8 days to obtain a filter membrane coated with the first layer of supramolecular material.

[0018] In this invention, the raw materials in the first raw material solution and the raw materials in the second raw material solution undergo a polymerization reaction on a supporting membrane at room temperature to generate supramolecular materials; the filter membrane coated with the first layer of supramolecular materials is immersed in the first raw material solution to obtain a second material coating membrane; the second material coating membrane is immersed in the second raw material solution to obtain a filter membrane coated with two layers of supramolecular materials; the steps are repeated 5 times, and vacuum drying is performed to obtain a filter membrane coated with 5 layers of supramolecular materials, namely the ordered multi-level porous supramolecular composite material filter membrane of this invention.

[0019] According to the present invention, preferably, in step S3;

[0020] Repeat steps S1-S2 4-6 times;

[0021] The vacuum drying temperature is 20-30℃.

[0022] According to the present invention, preferably, the pore size of the multi-level porous supramolecular composite filter membrane is 1.5-3.5 nm.

[0023] This invention modifies the surface of highly permeable and highly hydrophilic cellulose or glass fiber membranes. Utilizing the principle of interfacial polymerization, it employs in-situ growth and layer-by-layer transfer techniques to load multi-level porous supramolecular materials onto the fiber surface of the membrane. By controlling the composition of the raw materials and the deposition process, a filter membrane with adjustable pore size is achieved. This allows for the selective adsorption of organic molecules without affecting the high permeability of water and sodium chloride, thereby removing organic impurities.

[0024] The second aspect of the present invention provides a method for preparing a multi-level porous supramolecular composite filter membrane, thereby obtaining a multi-level porous supramolecular composite filter membrane.

[0025] The third aspect of this invention provides the application of the aforementioned multi-level porous supramolecular composite filter membrane in wastewater treatment.

[0026] According to the present invention, preferably, the multi-stage porous supramolecular composite material filter membrane is used to remove organic impurities from sodium chloride byproducts generated in chemical production; the content of organic impurities in the obtained sodium chloride solution after filtration is below 10 PPM, preferably, the content of inorganic ammonia is below 5 PPM.

[0027] The beneficial effects of the technical solution of the present invention are as follows:

[0028] This invention employs an in-situ growth layer-by-layer assembly process to tightly bond the multi-level porous supramolecular composite material with the support membrane, firmly attaching it to the surface of the support membrane.

[0029] The preparation conditions of this invention are mild. Due to the optimization of pore size, water molecules and sodium chloride can pass through while organic impurities are blocked. Therefore, it has high selectivity and can be widely used in wastewater treatment. It has the characteristics of high operational flexibility and high efficiency in treating organic impurities.

[0030] The filter membrane of this invention can be directly used in the treatment of high-concentration sodium chloride waste salt solutions, unaffected by the high concentration of sodium chloride, and does not require heating or other operations as in traditional treatment methods, thus reducing energy consumption. The sodium chloride solution obtained after filtration using the filter membrane of this invention can meet the requirements of the ion-exchange membrane caustic soda industry.

[0031] The multi-level porous supramolecular composite filter membrane of this invention contains a large number of hydrophilic functional groups on its surface, which endow the filter membrane with extremely strong hydrophilicity and surface activity. The supramolecular material and the supporting membrane are firmly fixed by chemical bonds, which can significantly improve the filtration performance of the filter membrane and extend its service life.

[0032] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation

[0033] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0034] Example 1

[0035] This embodiment provides a method for preparing a multi-level porous supramolecular composite filter membrane, the method comprising the following steps:

[0036] S1: At 25°C, the cellulose membrane is immersed in the first raw material solution (the raw material is 1,3,5-tris(4-aminophenyl)benzene, with a concentration of 1 mg / mL; the acidic catalyst is hydrochloric acid, with a concentration of 0.12 mol / L) for 1 h to obtain the material coating;

[0037] S2: At 25°C, the material membrane is immersed in a second raw material solution (the raw material is trialdehyde phloroglucinol with a concentration of 1 mg / mL; the acidic catalyst is hydrochloric acid with a concentration of 0.12 mol / L) for 7 days to obtain a filter membrane coated with the first layer of supramolecular material.

[0038] S3: Immerse the first layer of supramolecular material filter membrane into the first raw material solution, repeat steps S1-S2 4 times, and vacuum dry at 25°C to obtain the multi-level porous supramolecular composite filter membrane with a pore size of 1.7 nm.

[0039] Example 2

[0040] This embodiment provides a method for preparing a multi-level porous supramolecular composite filter membrane. The only difference between this embodiment and Embodiment 1 is that:

[0041] The raw material for the second raw material solution is 5'-(4-formyl-3-hydroxyphenyl)-3,3”-dihydroxy-[1,1':3',1”-terphenyl]-4,4”-dicarboxaldehyde;

[0042] This embodiment yields a multi-level porous supramolecular composite filter membrane with a pore size of 2.4 nm.

[0043] Example 3

[0044] This embodiment provides a method for preparing a multi-level porous supramolecular composite filter membrane. The only difference between this embodiment and Embodiment 1 is that:

[0045] Replace "cellulose membrane" with "glass fiber membrane";

[0046] In this embodiment, the multi-level porous supramolecular composite filter membrane obtained has a pore size of 2.3 nm.

[0047] Example 4

[0048] This embodiment provides a method for preparing a multi-level porous supramolecular composite filter membrane. The only difference between this embodiment and Embodiment 1 is that:

[0049] Replace "cellulose membrane" with "glass fiber membrane";

[0050] The raw material for the second raw material solution is 2,5-dimethoxy-p-phenylenedialdehyde;

[0051] In this embodiment, the multi-level porous supramolecular composite filter membrane obtained has a pore size of 3.2 nm.

[0052] Example 5

[0053] This embodiment provides a method for preparing a multi-level porous supramolecular composite filter membrane. The only difference between this embodiment and Embodiment 1 is that:

[0054] Replace "cellulose membrane" with "glass fiber membrane";

[0055] The raw material for the first raw material solution is trialdehyde phloroglucinol;

[0056] The raw material for the second raw material solution is benzidine;

[0057] In this embodiment, the multi-level porous supramolecular composite filter membrane obtained has a pore size of 2.8 nm.

[0058] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing a multi-level porous supramolecular composite filter membrane, characterized in that, The preparation method includes the following steps: S1: Immerse the support membrane in the first raw material solution to obtain a material coating; S2: Immerse the material coating into the second raw material solution to obtain a filter membrane coated with the first layer of supramolecular material; S3: Immerse the first layer of supramolecular material filter membrane into the first raw material solution, repeat steps S1-S2 multiple times, and vacuum dry to obtain the multi-level porous supramolecular composite material filter membrane. The supporting membrane is a cellulose membrane or a glass fiber membrane; The first and second raw material solutions each independently consist of the following components: raw material, water, and acidic catalyst; The raw materials are 1,3,5-tris(4-aminophenyl)benzene, trialdehyde phloroglucinol, 5'-(4-formyl-3-hydroxyphenyl)-3,3''-dihydroxy-[1,1':3',1''-terphenyl]-4,4''-dicarboxaldehyde, 2,5-dimethoxy-p-phenylenedialdehyde, or biphenyl diamine; the concentration of each raw material in the first and second raw material solutions is independently 0.8-1.2 mg / mL. The acidic catalyst is at least one of formic acid, acetic acid, and hydrochloric acid, and the concentration of the acidic catalyst in the first raw material solution and the second raw material solution is independently 0.01-0.15 mol / L.

2. The method for preparing the multi-level porous supramolecular composite filter membrane according to claim 1, wherein, In step S1, the support membrane is immersed in the first raw material solution at 20-30°C for 30-80 minutes to obtain a material coating.

3. The method for preparing the multi-level porous supramolecular composite filter membrane according to claim 1, wherein, In step S2, the material coating is immersed in the second raw material solution at 20-30°C for 5-8 days to obtain a filter membrane coated with the first layer of supramolecular material.

4. The method for preparing the multi-level porous supramolecular composite filter membrane according to claim 1, wherein, In step S3; Repeat steps S1-S2 4-6 times; The vacuum drying temperature is 20-30℃.

5. The method for preparing the multi-level porous supramolecular composite filter membrane according to claim 1, wherein, The pore size of the multi-level porous supramolecular composite filter membrane is 1.5-3.5 nm.

6. The multi-level porous supramolecular composite filter membrane prepared by the method of any one of claims 1-5.

7. The application of the multi-level porous supramolecular composite filter membrane according to claim 6 in wastewater treatment.

8. The application according to claim 7, wherein, The multi-stage porous supramolecular composite material filter membrane is used to remove organic impurities from sodium chloride byproducts produced in chemical production; the content of organic impurities in the obtained sodium chloride solution after filtration is below 10 PPM.