An ultra-high loading hydrogen-bonded organic framework anion separation membrane, and a preparation method and application thereof

Abstract

The application discloses an anion separation membrane of hydrogen-bonded organic framework with super-high loading capacity, and has the structural general formula: Compared with the prior art, the HOFs used in the application have regular and moderate pore diameters, can selectively transport ions, and the porous structure composed of flexible hydrogen bonds can effectively screen different size ions, thereby enhancing the ion separation performance of the membrane. Anion separation performance test results show that the HOFs anion separation membrane has excellent anion separation performance, and the ion screening performance is improved by more than 6 times compared with a commercial Neosepta ACS membrane, and the HOFs anion separation membrane prepared by the application can be used for anion separation.

Description

Technical Field

[0001] This invention relates to the field of separation membrane technology, specifically to an ultra-high loading hydrogen-bonded organic framework anion separation membrane, its preparation method, and its application. Background Technology

[0002] With the continuous development of society, economy, and industrialization, environmental pollution problems have also arisen. For example, industries such as coal chemical, petroleum, metallurgy, photovoltaic, and semiconductor manufacturing generate large amounts of high-concentration chlorides, fluorides, bromides, nitrates, and sulfates. How to economically and efficiently treat these saline wastewaters is of great significance for the sustainable and green development of society. Among various separation methods, membrane separation technology can achieve ion separation and recovery, and is low-carbon and environmentally friendly, attracting widespread attention. Hybrid matrix membranes, composed of polymer matrices and porous packing materials, combine the inherent advantages of polymer membranes with the excellent ion separation performance of porous packing materials, effectively improving the ion separation performance of the membrane.

[0003] When the filler content is high, an ion transport pathway dominated by the porous structure of the filler will be constructed within the membrane, which is more conducive to efficient ion separation. However, excessive filler content may also lead to problems such as filler deposition, agglomeration, and filler-matrix interface defects. Therefore, it is essential to prepare an ion separation membrane with ultra-high loading capacity and stable, defect-free properties for practical applications.

[0004] Patent CN115869791A discloses a method for preparing and applying a mixed matrix membrane based on porous organic cages. The method involves uniformly dispersing porous organic cages in a polymer matrix and preparing the mixed matrix membrane using a scraping method. While the mixed matrix membrane obtained by this method shows significantly improved separation performance compared to pure polymer membranes, its ion sieving capacity needs further improvement due to the low loading of porous organic cages.

[0005] Patent CN114950167A discloses a method for preparing ultra-high MOF-based hybrid matrix membranes. Utilizing the skeletal structure of the polymer matrix and dopamine molecules loaded on MOFs, the compatibility between the filler and the polymer matrix is ​​improved, with MOF content reaching up to 60 wt.% or more. However, this method is relatively cumbersome, and the stability of the dopamine molecules loaded on the MOFs requires further investigation.

[0006] Hydrogen-bonded organic frameworks (HOFs), as a novel class of porous crystalline materials, were first prepared by Chen Banglin et al., who demonstrated the ability to separate C2H2 / C2H4 structures using permanently porous HOFs (A Microporous Hydrogen-Bonded Organic Framework for Highly Selective C2H2 / C2H4 Separation at Ambient Temperature, Journal of the American Chemical Society, 2011-08-24). Due to their ability to be regenerated and healed through simple recrystallization, good solution processability, uniform pore size structure, large specific surface area and porosity, and good chemical and thermal stability, HOFs have been widely used in gas separation and storage, proton conduction, sensing, and biomedicine in recent years. However, the application of HOFs in ion separation is almost nonexistent.

[0007] Although HOFs mainly contain elements such as carbon, hydrogen, oxygen, and nitrogen, and have good intrinsic compatibility with polymer matrices, due to the differences in the properties and structures of porous materials and organic matrices, a stable homogeneous structure cannot be formed when a high content of porous materials is loaded inside an organic matrix. This makes it challenging to prepare high-load mixed matrix membranes with excellent ion sieving capabilities. Summary of the Invention

[0008] To address the shortcomings in this field, this invention proposes a method for preparing an anion separation membrane with ultra-high loading of hydrogen-bonded organic frameworks (HOFs). The anion separation membrane prepared by this invention has an ultra-high HOF loading and also exhibits superior ion transport rate and selectivity.

[0009] To achieve the above objectives, the first aspect of the present invention provides a hydrogen-bonded organic framework anion separation membrane with ultra-high loading capacity, having the following general structural formula:

[0010]

[0011] Wherein, 1000>m>10, 3000>n>10, R is α-D glucose or β-D glucose, and R′ includes, but is not limited to, ethyl, propyl, butyl, and pentyl;

[0012] The HOF includes the following basic structural units:

[0013]

[0014] Wherein, R1 is benzene or biphenyl, and R2 is an alkane with 0, 1, or 2 carbon atoms;

[0015] DAT1 and DAT2 have the following structures:

[0016]

[0017] The second aspect of this invention provides a method for preparing an ultra-high loading hydrogen-bonded organic framework anion separator, characterized in that a polymer matrix containing both carboxyl and hydroxyl groups and HOFs having diamino dimer supramolecular structural units are used as the main raw materials. Water, inorganic acid, and dialdehyde crosslinking agent are added, and the mixture undergoes acidification, amidation, and crosslinking reactions in sequence to prepare a membrane solution containing HOFs. The membrane solution is then coated onto the surface of a membrane substrate to form a membrane, which is then dried and demolded to obtain an ultra-high loading HOFs anion separator.

[0018] Preferably, the polymer matrix containing both carboxylate and hydroxyl groups has the following structural formula:

[0019]

[0020] Among them, M + Cations used for charge balance, including but not limited to Na + K + Ca 2+ wait;

[0021] Wherein, R is α-D glucose or β-D glucose;

[0022] The polymer matrix includes, but is not limited to: sodium carboxymethyl cellulose (CMC-Na) and sodium alginate (SA);

[0023] The molecular weight of the polymer matrix is ​​10,000 g / mol to 700,000 g / mol;

[0024] 3000>n>10.

[0025] Preferably, the HOF having diamino dimer supramolecular structural units, wherein the HOF comprises the following basic structural units,

[0026]

[0027] Wherein, R1 is benzene or biphenyl, and R2 is an alkane with 0, 1, or 2 carbon atoms;

[0028] DAT1 and DAT2 have the following structures:

[0029]

[0030] The HOFs having diamino dimer supramolecular structural units include, but are not limited to, 4,4',4",4"'-tetracyano(4,6-diamino-s-triazine-2-yl)tetraphenylmethane, 4,4',4"-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))-6,6',6"-tris(1,3,5-triazine-2,4-diamine), 3,5-tris(2,4-diamino-1,3,5-triazine-6-yl)-2,4,6-trimethylbenzene, and 2,7-bis(5-amino-1H-1,2,4-triazacyclo-3-yl)-1,2,3,6,7,8-hexaiso[6,5,4-def]iso-1,3,6,8-tetraone.

[0031] The mass ratio of HOF to polymer matrix is ​​(1-60):100.

[0032] Preferably, the inorganic acid includes, but is not limited to, one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0033] Preferably, the crosslinking agent is a dialdehyde solution with the following structural formula:

[0034] OHC-R'-CHO

[0035] R′ includes, but is not limited to, ethyl, propyl, butyl, and pentyl;

[0036] The mass ratio of the crosslinking agent to the polymer matrix is ​​(0.01-100):100.

[0037] Preferably, the acidification reaction equation is as follows:

[0038]

[0039] The reaction temperature is 20℃-60℃, and the reaction time is 0.5h-3h;

[0040] The amidation reaction equation is as follows:

[0041]

[0042] The reaction temperature is 30℃-90℃, and the reaction time is 0.5h-3h;

[0043] The crosslinking reaction equation is as follows:

[0044]

[0045] The reaction temperature is 30℃-90℃, and the reaction time is 0.5h-6h.

[0046] Preferably, the substrate includes, but is not limited to, polyvinylidene fluoride, nylon, polyethersulfone, polycarbonate, etc.

[0047] The substrate has a pore size of 0.1 μm to 0.45 μm;

[0048] The drying temperature is 30℃-100℃.

[0049] Preferably, the HOF content in the anion exchange membrane ranges from 0% to 60%.

[0050] A third aspect of this invention provides an anion separation membrane prepared by the above method for use in anion separation; wherein the anion is Cl. - / NO3 - Cl - SO4 2- NO3 - SO4 2- F - SO4 2- , Br - SO4 2- Cl - / PO4 3- One or more of the following; the anion separation is performed using diffusion dialysis.

[0051] Compared with the prior art, the beneficial effects of the present invention are:

[0052] (1) The HOFs used in this invention have regular and moderate pore size, which can selectively transport ions, and the porous structure composed of flexible hydrogen bonds can effectively sieve ions of different sizes, thereby enhancing the membrane ion separation performance.

[0053] (2) The HOFs and polymer matrix used in this invention can form certain bonds and interactions, which enhances the binding force between HOFs and polymer matrix, increases the loading of HOFs in the matrix, provides more transport paths for ion selective separation, and enhances ion separation performance.

[0054] (3) The polymer matrix used in this invention is rich in hydroxyl groups, which can undergo cross-linking reaction with the cross-linking agent to enhance the swelling resistance and stability of the membrane. In addition, during the cross-linking process, the polymer chains wrap around and encapsulate the HOFs material, further improving the loading and stability of HOFs in the polymer matrix.

[0055] (4) The method used in this invention is simple, the separation process is energy-saving and environmentally friendly, the HOF loading of the prepared membrane can reach up to 60%, and it has good mechanical properties and excellent ion separation performance. Attached Figure Description

[0056] Figure 1The images show the infrared spectra of the 20% HOF-CMC ion separation membrane prepared in Example 4, the pure CMC membrane in Comparative Example 1, and the HOF+CMC mixed membrane. The figures show that after introducing HOFs, the membrane at 1580 cm⁻¹... -1 The intensity of the primary amine stretching vibration peak at the wavenumber was significantly reduced, indicating that the amidation reaction between the amino and carboxyl groups consumed the primary amine content in the HOFs;

[0057] Figure 2 The images show scanning electron microscope (SEM) images of the 20% HOF-CMC ion separation membrane (left) prepared in Example 4 and the pure CMC membrane (right) in Comparative Example 1. As can be seen from the images, the membrane surfaces are uniform and dense.

[0058] Figure 3 The images show cross-sectional scanning electron microscope (SEM) images of the 20% HOF-CMC ion separation membrane (left) prepared in Example 4 and the pure CMC membrane (right) in Comparative Example 1. As can be seen from the images, the HOFs are uniformly dispersed within the membrane and have good compatibility with the matrix, without defects or aggregation.

[0059] Figure 4 The figures show the X-ray diffraction (XRD) spectra of the 40% HOF-CMC ion separation membrane prepared in Example 5, the 20% HOF-CMC ion separation membrane prepared in Example 4, and the pure CMC membrane in Comparative Example 1. As can be seen from the figures, with the increase of HOF content, the characteristic peaks of HOFs gradually appear in the XRD patterns, indicating that the amino groups reacting with the carboxyl groups are the edge amino groups of HOFs, and that the crystal structure of HOFs can stably exist in the polymer matrix. Detailed Implementation

[0060] Unless otherwise stated, all parts in this invention are parts by weight;

[0061] Unless otherwise stated, all raw materials and reagents used in this invention are commercially available products, or can be directly customized from a chemical reagent customization factory, or prepared in-house.

[0062] Among them, sodium carboxymethyl cellulose (CMC-Na), sodium alginate (SA), hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, glyoxal, malondialdehyde, succinaldehyde, and glutaraldehyde were purchased from Aladdin.

[0063] Polyvinylidene fluoride, nylon, polyethersulfone, and polycarbonate were purchased from Jinteng Experimental Equipment Co., Ltd.

[0064] Sources of HOFs (taking HOFs-4 as an example, it is prepared by using 3,5-diamino-1,2,4-triazole and 1,4,5,8-naphthalenetetracarboxylic dianhydride as raw materials, NN-dimethylacetamide as solvent, and a solvothermal method, reacting at 180℃ for 10h).

[0065] 4,4',4”'-Tetracyano(4,6-diamino-S-triazine-2-yl)tetraphenylmethane, denoted as HOFs-1, has the following structural formula:

[0066]

[0067] 4,4',4"-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))-6,6',6"-tris(1,3,5-triazine-2,4-diamine), denoted as HOFs-2, has the following structural formula:

[0068]

[0069] 5-Tris(2,4-diamino-1,3,5-triazin-6-yl)-2,4,6-trimethylbenzene, denoted as HOFs-3, has the following structural formula:

[0070]

[0071] 2,7-Bis(5-amino-1H-1,2,4-triazacyclo-3-yl)-1,2,3,6,7,8-hexaiso[6,5,4-def]iso-1,3,6,8-tetraone, denoted as HOFs-4, has the following structural formula:

[0072]

[0073] Example 1, as a comparative example 1

[0074] 1. In this embodiment, the mass fraction of HOFs is 0.

[0075] A method for preparing a pure polymer membrane includes the following steps:

[0076] Hydrochloric acid was added to 2g of a 1% sodium carboxymethyl cellulose (CMC-Na) or sodium alginate (SA) solution to adjust the polymer surface groups and acidify it. Then, 2mg of glutaraldehyde solution was added, and the mixture was stirred at 60℃ for 1h to allow it to react fully. The film solution was then uniformly coated onto the surface of a polyvinylidene fluoride substrate with a pore size of 0.22μm. The solvent was evaporated at 60℃ to form a film, which was denoted as CMC or SA.

[0077] 2. The pure polymer anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- , or Cl - / NO3 -、 or F - SO4 2- 、or Br - SO4 2- or NO3 -SO4 2- , or Cl - / PO4 3- .

[0078] The pure polymer anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 Cl - SO4 2- (or Cl) - / NO3 - 、 or F - SO4 2- 、or Br - SO4 2- or NO3 - SO4 2- , or Cl - / PO4 3- A mixed solution was prepared, with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization, and the test duration was 2 hours. Cl was measured by diffusion. - Concentration and SO4 2- Concentration calculations correspond to ion transport rates and selectivity.

[0079] The results show that for Cl - SO4 2- The selectivity of pure CMC membranes is only 3.7, corresponding to Cl... - The transmission rate is 3.7 mol m - 2 h -1 The selectivity of pure SA membrane is only 3.3, corresponding to Cl - The transmission rate is 3.9 mol m -2 h -1 The above-mentioned pure membrane has a high resistance to Cl. - SO4 2- Almost no separation performance;

[0080] For Cl - / NO3 - The selectivity of pure CMC membranes is only 1.1, corresponding to Cl... - The transmission rate is 1.9 mol m -2 h -1 ;

[0081] For F - SO4 2- The selectivity of pure CMC membranes is only 3.2, corresponding to F - The transmission rate is 3.2 mol m -2 h -1 ;

[0082] For Br - SO4 2- The selectivity of pure CMC membranes is only 4, corresponding to Br - The transmission rate is 3.9 mol m -2 h -1 ;

[0083] For NO3 - SO4 2- The selectivity of pure CMC membranes is only 3.7, corresponding to NO3. - The transmission rate is 3.8 mol m -2 h -1 ;

[0084] For Cl - / PO4 3- The selectivity of pure CMC membranes is only 3.7, corresponding to Cl... - The transmission rate is 3.8 mol m -2 h -1 .

[0085] Example 2

[0086] 1. A method for preparing an ultra-high loading HOFs anion exchange membrane, comprising the following steps:

[0087] Hydrochloric acid was added to 2g of a 1% CMC-Na solution to adjust the polymer surface groups and acidify it, converting CMC-Na to CMC. Then, 1mg of HOFs-4 was added, and the mixture was stirred at 60℃ for 2h. After stirring, 2mg of glutaraldehyde solution was added, and the mixture was stirred at 60℃ for 1h to allow for a complete reaction. The membrane solution was then uniformly coated onto the surface of polyvinylidene fluoride with a pore size of 0.22μm. The solvent was evaporated at 60℃ to obtain an HOFs mixed matrix membrane, denoted as 5% HOF-CMC.

[0088] 2. The 5% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2 .

[0089] The diffusion dialysis method is the same as that in Comparative Example 1.

[0090] The results show that the 5% HOF-CMC anion exchange membrane prepared in this embodiment has the desired effect on the overall performance. - SO4 2- The highest selectivity was 11.9, corresponding to Cl. - The transmission rate is 3.2 mol m -2 h -1Compared to the pure CMC membrane in Comparative Example 1, the 5% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl- ion exchange. - SO4 2- Selectivity was increased by up to 3.2 times, and separation performance was significantly improved.

[0091] Example 3

[0092] 1. In this embodiment, a 10% HOF-CMC anion exchange membrane was prepared using the same method as in Example 2.

[0093] 2. The 10% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0094] The diffusion dialysis method is the same as that in Comparative Example 1.

[0095] The results show that the 10% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 17.5, corresponding to Cl. - The transmission rate is 2.8 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 10% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2- Selectivity was increased by up to 4.7 times, and separation performance was significantly improved.

[0096] Example 4

[0097] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 2.

[0098] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0099] The diffusion dialysis method is the same as that in Comparative Example 1.

[0100] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 24.1, corresponding to Cl. - The transmission rate is 2.3 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-.- SO4 2- Selectivity was increased by up to 6.5 times, and separation performance was significantly improved.

[0101] Example 5

[0102] 1. In this embodiment, a 40% HOF-CMC anion exchange membrane was prepared using the same method as in Example 2.

[0103] 2. The 40% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0104] The diffusion dialysis method is the same as that in Comparative Example 1.

[0105] The results show that the 40% HOF-CMC anion exchange membrane prepared in this embodiment has the desired effect. - SO4 2- The highest selectivity was 20.6, corresponding to Cl. - The transmission rate is 1.7 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 40% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2- Selectivity was increased by up to 5.6 times, and separation performance was significantly improved.

[0106] Example 6

[0107] 1. In this embodiment, a 60% HOF-CMC anion exchange membrane was prepared using the same method as in Example 2.

[0108] 2. The 60% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0109] The diffusion dialysis method is the same as that in Comparative Example 1.

[0110] The results show that the 60% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 15.3, corresponding to Cl. - The transmission rate is 1.2 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 60% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2-Selectivity was increased by up to 4.1 times, and separation performance was significantly improved.

[0111] Example 7

[0112] 1. This embodiment follows the same method as in Example 2, except that the polymer matrix CMC-Na is changed to SA to prepare a 20% HOF-SA anion exchange membrane.

[0113] 2. The 20% HOF-SA anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0114] The diffusion dialysis method is the same as that in Comparative Example 1.

[0115] The results show that the 20% HOF-SA anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 22.1, corresponding to Cl. - The transmission rate is 2.1 mol m -2 h -1 Compared to the pure SA membrane in Comparative Example 1, the 20% HOF-SA anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2- Selectivity was increased by up to 6.7 times, and separation performance was significantly improved.

[0116] Example 8

[0117] 1. This embodiment follows the same method as in Example 2, except that the crosslinking agent glutaraldehyde is replaced with glyoxal to prepare a 20% HOF-CMC anion exchange membrane.

[0118] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0119] The diffusion dialysis method is the same as that in Comparative Example 1.

[0120] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 26.7, corresponding to Cl. - The transmission rate is 1.9 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2-Selectivity was increased by up to 7.2 times, and separation performance was significantly improved.

[0121] Example 9

[0122] 1. This embodiment follows the same method as in Example 2, except that the crosslinking agent glutaraldehyde is replaced with butyraldehyde to prepare a 20% HOF-CMC anion exchange membrane.

[0123] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0124] The diffusion dialysis method is the same as that in Comparative Example 1.

[0125] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 26.1, corresponding to Cl. - The transmission rate is 2.0 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2- Selectivity was increased by up to 7.1 times, and separation performance was significantly improved.

[0126] Example 10

[0127] 1. This embodiment follows the same method as in embodiment 2, except that the substrate is changed from polyvinylidene fluoride to nylon to prepare a 20% HOF-CMC anion exchange membrane.

[0128] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0129] The diffusion dialysis method is the same as that in Comparative Example 1.

[0130] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity was 23.3, corresponding to Cl. - The transmission rate is 2.5 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2-Selectivity was increased by up to 6.3 times, and separation performance was significantly improved.

[0131] Example 11

[0132] 1. This embodiment follows the same method as in Example 2, except that the substrate polyvinylidene fluoride is replaced with polyethersulfone to prepare a 20% HOF-CMC anion exchange membrane.

[0133] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0134] The diffusion dialysis method is the same as that in Comparative Example 1.

[0135] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity is 25.2, corresponding to Cl. - The transmission rate is 2.1 mol m -2 h -1 Compared to pure CMC in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2- Selectivity was increased by up to 6.8 times, and separation performance was significantly improved.

[0136] Example 12

[0137] 1. This embodiment follows the same method as in Example 2, except that the substrate polyvinylidene fluoride is replaced with polycarbonate to prepare a 20% HOF-CMC anion exchange membrane.

[0138] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - SO4 2- .

[0139] The diffusion dialysis method is the same as that in Comparative Example 1.

[0140] The results show that the 20% HOF-CMC anion exchange membrane Cl prepared in this embodiment has good performance. - SO4 2- The highest selectivity is 25.2, corresponding to Cl. - The transmission rate is 2.2 mol m -2 h -1 Compared to the pure CMC membrane in Comparative Example 1, the 20% HOF-CMC anion exchange membrane prepared in this example shows better performance for Cl-. - SO4 2-Selectivity was increased by up to 6.8 times, and separation performance was significantly improved.

[0141] Example 13

[0142] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 2.

[0143] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - / NO3 - .

[0144] The 20% HOF-CMC anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 Cl - / NO3 - The mixed solution was prepared with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization. The test duration was 2 hours. Cl was measured by diffusion dialysis. - Concentration and NO3 - Concentration calculations correspond to ion transport rates and selectivity.

[0145] The results show that the 20% HOF-CMC separation membrane Cl prepared in this embodiment - / NO3 - The highest selectivity is 3.3, corresponding to Cl. - The transmission rate is 1.8 mol m -2 h -1 In contrast, the selectivity of the pure CMC membrane in Comparative Example 1 was only 1.1, corresponding to Cl... - The transmission rate is 1.9 mol m -2 h -1 In comparison, the 20% HOF-CMC anion exchange membrane prepared in this embodiment has better performance against Cl-. - / NO3 - Selectivity was increased by up to 3.0 times, Cl - The transport rate decreased slightly. In summary, the hydrogen-bonded organic framework anion separation membrane prepared in this example achieves Cl... - / NO3 - The separation performance has been greatly improved.

[0146] Example 14

[0147] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 4.

[0148] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate F in a mixed solution. - SO4 2- .

[0149] The 20% HOF-CMC anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 F - SO4 2- The mixed solution was prepared with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization. The test duration was 2 hours. The diffusion efficiency was measured using the F-method. - Concentration and SO4 2- Concentration calculations correspond to ion transport rates and selectivity.

[0150] The results show that the 20% HOF-CMC separation membrane F prepared in this embodiment is effective. - SO4 2- The highest selectivity is 16.4, corresponding to F. - The transmission rate is 1.5 mol m -2 h -1 In contrast, the selectivity of the pure CMC membrane in Comparative Example 1 was only 3.2, corresponding to F... - The transmission rate is 3.2 mol m -2 h -1 In comparison, the 20% HOF-CMC anion exchange membrane prepared in this embodiment is more effective against F... - SO4 2- Selectivity increased by 5.1 times, F - The transport rate decreased slightly. In summary, the hydrogen-bonded organic framework anion exchange membrane prepared in this example achieved F... - SO4 2- The separation performance has been greatly improved.

[0151] Example 15

[0152] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 4.

[0153] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Br in a mixed solution. - SO4 2- .

[0154] The 20% HOF-CMC anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 Br- SO4 2- The mixed solution was prepared with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization. The test duration was 2 hours. Br was measured by diffusion. - Concentration and SO4 2- Concentration calculations correspond to ion transport rates and selectivity.

[0155] The results show that the 20% HOF-CMC separation membrane Br prepared in this embodiment... - SO4 2- The highest selectivity was 29.7, corresponding to Br - The transmission rate is 2.9 mol m -2 h -1 In contrast, the selectivity of the pure CMC membrane in Comparative Example 1 was only 4, corresponding to Br - The transmission rate is 3.9 mol / m. -2 h -1 In comparison, the 20% HOF-CMC anion exchange membrane prepared in this embodiment is more effective against Br. - SO4 2- Selectivity increased by up to 7.4 times, Br - The transport rate decreased slightly. In summary, the hydrogen-bonded organic framework anion exchange membrane prepared in this example achieves Br... - SO4 2- The separation performance has been greatly improved.

[0156] Example 16

[0157] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 4.

[0158] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate NO3 from a mixed solution. - SO4 2- .

[0159] The 20% HOF-CMC anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 NO3 - SO4 2- The mixed solution was prepared with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization. The test duration was 2 hours. NO3 was measured by diffusion dialysis. - Concentration and SO4 2- Concentration calculations correspond to ion transport rates and selectivity.

[0160] The results show that the 20% HOF-CMC membrane prepared in this embodiment can effectively separate NO3. - SO4 2- The highest selectivity was 26.9, corresponding to NO3. - The transmission rate is 2.7 mol m -2 h -1 In contrast, the selectivity of the pure CMC membrane in Comparative Example 1 was only 3.7, corresponding to NO3... - The transmission rate is 3.8 mol m -2 h -1 In comparison, the 20% HOF-CMC anion exchange membrane prepared in this embodiment is more effective against NO3-. - SO4 2- Selectivity increased by up to 7.3 times, NO3 - The transmission rate decreased slightly. In summary, the 20% HOF-CMC anion exchange membrane prepared in this example achieved NO3... - SO4 2- The separation performance has been greatly improved.

[0161] Example 17

[0162] 1. In this embodiment, a 20% HOF-CMC anion exchange membrane was prepared using the same method as in Example 4.

[0163] 2. The 20% HOF-CMC anion exchange membrane prepared in this embodiment was applied to diffusion dialysis to separate Cl in a mixed solution. - / PO4 3- .

[0164] The 20% HOF-CMC anion exchange membrane prepared in this embodiment was placed in a diffusion dialysis apparatus, wherein 100 mL of 0.5 mol / L solution was added to one side of the membrane. -1 Cl - / PO4 3- The mixed solution was prepared, with 100 mL of deionized water added to one side of the substrate. A magnetic stir bar was added to the diffusion dialysis apparatus to reduce the effect of concentration polarization. The test duration was 2 hours. Cl was measured by diffusion. - Concentration and PO4 3- Concentration calculations correspond to ion transport rates and selectivity.

[0165] The results show that the 20% HOF-CMC separation membrane Cl prepared in this embodiment - / PO4 3- The highest selectivity was 16.8, corresponding to Cl. - The transmission rate is 2.4 mol m -2 h -1 In contrast, the selectivity of the pure CMC membrane in Comparative Example 1 was only 3.7, corresponding to Cl... -The transmission rate is 3.8 mol m -2 h -1 In comparison, the 20% HOF-CMC anion exchange membrane prepared in this embodiment has better performance against Cl-. - / PO4 3- Selectivity increased by up to 4.5 times, Cl - The transport rate decreased slightly. In summary, the hydrogen-bonded organic framework anion separation membrane prepared in this example achieves Cl... - / PO4 3- The separation performance has been greatly improved.

[0166] As demonstrated by the above examples, the ultra-high loading HOFs anion exchange membrane prepared by this invention exhibits excellent anion separation performance. Furthermore, compared to the commercial Neosepta ACS membrane, its ion sieving performance is improved by more than 6 times. In addition, the membrane prepared by this invention is adaptable to different anion separation systems, demonstrating excellent separation performance and showing broad application prospects in the treatment of saline wastewater and the separation and purification of high-value-added ions.

[0167] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-high loading hydrogen-bonded organic framework anion separation membrane, characterized in that, Using sodium carboxymethyl cellulose or sodium alginate and HOF with diamino dimer supramolecular structural units as the main raw materials, water, inorganic acid and dialdehyde crosslinking agent are added, and the membrane solution containing HOFs is prepared by acidification reaction, amidation reaction and crosslinking reaction in sequence. The membrane solution is coated on the surface of the membrane substrate to form a membrane, and after drying and demolding, an ultra-high loading HOFs anion separation membrane is obtained.

2. The method according to claim 1, characterized in that, The HOF having diamino dimer supramolecular structural units, wherein the HOF includes the following basic structural units. ； Wherein, R1 is benzene or biphenyl, and R2 is an alkane with 1 or 2 carbon atoms; DAT1 and DAT2 have the following structures: ； The HOF having diamino dimer supramolecular structural units is 4,4',4'',4'''-tetracyano(4,6-diamino-s-triazine-2-yl)tetraphenylmethane, 4,4',4"-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))-6,6',6"-tris(1,3,5-triazine-2,4-diamine), 3,5-tris(2,4-diamino-1,3,5-triazine-6-yl)-2,4,6-trimethylbenzene or 2,7-bis(5-amino-1H-1,2,4-triazacyclo-3-yl)-1,2,3,6,7,8-hexaiso[6,5,4-def]iso-1,3,6,8-tetraone; The mass ratio of HOF to sodium carboxymethyl cellulose is 1:20; The mass ratio of HOF to sodium alginate is 1:

20.

3. The method according to claim 1, characterized in that, The inorganic acid includes one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

4. The method according to claim 1, characterized in that, The crosslinking agent is a dialdehyde solution with the following structural formula: ； R' is (-CH2-) n n is 0-3; The mass ratio of the crosslinking agent to sodium carboxymethyl cellulose is 1:10; The mass ratio of the crosslinking agent to sodium alginate is 1:

10.

5. The method according to claim 1, characterized in that, The substrate is polyvinylidene fluoride, nylon, polyethersulfone, or polycarbonate; The substrate has a pore size of 0.1 μm-0.45 μm; The drying temperature is 30℃-100℃.

6. The anion separation membrane obtained by the preparation method according to any one of claims 1-5 is applied to anion separation; wherein the anion is Cl. - / NO3 - Cl - SO4 2- NO3 - SO4 2- F - SO4 2- , Br - SO4 2- Cl - / PO4 3- One or more of the following; the anion separation is performed using diffusion dialysis.

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