Anionic membrane as well as preparation method and application thereof

Abstract

The invention provides an anionic membrane as well as a preparation method and application thereof. The preparation method of the anionic membrane comprises the following steps: S1, prepolymerization: dissolving a first unsaturated monomer containing a halogen group, a second unsaturated monomer and an initiator in an organic solvent, and carrying out polymerization reaction after dissolving to obtain a membrane casting solution; s2, curing: coating a supporting base material with the membrane casting solution, and curing to form a membrane; s3, functional modification: transferring a membrane into an organic amine solution for soaking after the membrane is completely cured to form a membrane, and fully reacting to obtain a functional modified anionic membrane; the molar ratio of the first unsaturated monomer to the second unsaturated monomer is 1: (0.03-0.10). According to the preparation method, the use of high-carcinogenicity chemicals such as chloromethyl methyl ether is avoided, the green production of the high-performance anion membrane is realized, the accurate regulation and control of the physical and chemical properties of the anion membrane are also realized, and higher current efficiency and lower unit energy consumption are obtained when the anion membrane is applied to the salt concentration test of electrodialysis.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically comprises an anion membrane and a preparation method and application thereof. Background Art

[0002] Anion exchange membranes (AEMs), as one of the core categories of ion exchange membranes, play an irreplaceable role in alkaline fuel cells, electrodialysis, electrochemical reduction of carbon dioxide, hydrogen production from water electrolysis, and industrial wastewater treatment. Their core function is to selectively transmit anions through positively charged groups (such as quaternary ammonium groups) fixed within the membrane, while blocking cations and neutral molecules, thereby achieving efficient regulation of ion transport. However, the preparation process of traditional anion membranes has long relied on hazardous chemicals such as chloromethyl ether (CMME) as key raw materials for chloromethylation or cross-linking reactions of functional groups. This process not only poses serious safety risks (chloromethyl ether is listed as a strong carcinogen), but also faces strict restrictions of environmental regulations, which greatly restricts the large-scale production and commercial application of anion membranes.

[0003] Currently, the preparation technology of anion membranes is mainly based on a two-step process: first, chloromethyl groups are introduced into the polymer backbone (such as polysulfone, polyphenylene ether) through a chloromethylation reaction, and then the chloromethyl groups are converted into quaternary ammonium groups through a quaternization reaction. Among them, chloromethyl ether is widely used as a chloromethylation agent due to its high reactivity, but its severe toxicity, volatility and by-products generated during the production process (such as formaldehyde and hydrogen chloride) pose a significant threat to the health of operators and the ecological environment. In addition, the strict control of chloromethyl ether has led to an increase in the cost of obtaining raw materials, and its residues may affect the long-term chemical stability of the membrane, especially under high temperature or strong alkaline conditions, which is prone to degradation, limiting the service life of the membrane.

[0004] In recent years, research on chloromethyl ether alternative technologies has become an important direction in the field of anion membranes. Some attempts include adopting non-chloromethylation routes (such as direct synthesis of monomers containing quaternary ammonium groups), using low-toxicity methylating reagents (such as iodomethane, dimethyl carbonate), or developing solvent-free green synthesis processes. However, these methods still have significant bottlenecks: for example, the synthesis of direct functionalized monomers is difficult and expensive; the reaction efficiency of alternative reagents is insufficient, resulting in low density of membrane functional groups and decreased ion conductivity; or the complexity of the process increases the difficulty of industrial production. Therefore, how to achieve efficient and low-cost preparation of anion membranes while abandoning chloromethyl ether and ensuring their electrochemical performance and durability has become a technical problem that needs to be broken through. Summary of the Invention

[0005] Summary of the invention For the problems referred to above that prior art exists, first object of the present invention is to provide a kind of preparation method of anionic membrane.Through molecular structure design and reaction path optimization, the use of chloromethyl ether is saved fully in the preparation process of anionic membrane, and the safety and environmental risk that it brings is eliminated from the source.In addition, this technology simplifies traditional multi-step reaction process, reduces energy consumption and raw material cost, and provides practical solution for the greenization of anionic membrane, large-scale production, and has outstanding industrial application prospect and social and economic benefit.

[0006] The second object of the present invention is to provide an anion membrane prepared by the above-mentioned preparation method.

[0007] The third object of the present invention is to provide an application of the anion membrane described above in electrodialysis.

[0008] To achieve the above first object, the technical solution adopted by the present invention includes:

[0009] The present invention discloses a method for preparing an anion membrane, comprising the following steps:

[0010] S1, prepolymerization: dissolving the first unsaturated monomer containing a halogen group, the second unsaturated monomer and an initiator in an organic solvent, and performing a polymerization reaction after dissolution to obtain a casting solution;

[0011] S2, solidification: coating the casting solution on the supporting substrate and solidifying it into a film;

[0012] S3. Functional modification: After the membrane is completely solidified, the membrane is transferred to an organic amine solution and fully reacted under closed conditions to obtain a functionally modified anion membrane;

[0013] The molar ratio of the first unsaturated monomer to the second unsaturated monomer is 1:0.03 to 0.10; for example, the molar ratio of the first unsaturated monomer to the second unsaturated monomer may be 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, 1:0.10, etc.

[0014] Furthermore, the first unsaturated monomer includes but is not limited to one of p-vinylbenzyl chloride, m-vinylbenzyl chloride, p-chlorostyrene, m-chlorostyrene, p-bromostyrene and m-bromostyrene;

[0015] The second unsaturated monomer includes, but is not limited to, o-divinylbenzene and / or p-divinylbenzene.

[0016] Furthermore, the initiator includes but is not limited to one or more of dibenzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, diethylhexyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptylonitrile, and tetraethylthiuram;

[0017] The organic solvent includes, but is not limited to, one or more of tetrahydrofuran, N-methylpyrrolidone, and N,N-dimethylformamide.

[0018] Further, the molar ratio of the first unsaturated monomer to the initiator is 1:0.002 to 0.05; illustratively, the molar ratio of the first unsaturated monomer to the initiator can be 1:0.002, 1:0.005, 1:0.01, 1:0.015, 1:0.02, 1:0.025, 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, etc.

[0019] Furthermore, the molar ratio of the first unsaturated monomer to the organic solvent is 1:0.5-5; illustratively, the molar ratio of the first unsaturated monomer to the organic solvent is 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, etc.

[0020] Furthermore, the polymerization reaction temperature is 40 to 70° C., and the polymerization reaction time is 1 to 4 hours.

[0021] Furthermore, the supporting substrate includes but is not limited to one of non-woven fabric, polypropylene mesh, polyvinyl chloride mesh, nylon mesh, polyester mesh, polyetheretherketone mesh, polyethylene film, and polypropylene film, and its thickness is 0.05 to 0.3 mm.

[0022] Furthermore, the curing reaction temperature is 70 to 100° C., and the curing reaction time is 12 to 24 hours.

[0023] Furthermore, the concentration of the organic amine solution is 30 to 60%;

[0024] The organic amine solution includes but is not limited to one or more of trimethylamine solution, triethylamine solution, tripropylamine solution, N,N-dicyclohexylmethylamine, N,N-dimethylaniline, N-propyldicyclohexylamine, N-methyldiethanolamine, and triethanolamine;

[0025] The reaction temperature of step S3 is 40-60° C., and the reaction time is 12-24 h.

[0026] To achieve the above second purpose, the technical solutions adopted by the present invention include:

[0027] The present invention discloses an anion membrane prepared by the above-mentioned preparation method.

[0028] To achieve the third objective, the present invention employs the following technical solutions:

[0029] The present invention discloses an application of the anion membrane described above in electrodialysis.

[0030] Beneficial effects of the present invention:

[0031] The present invention develops a highly efficient, low-cost, green and sustainable method for preparing anionic membranes. In this preparation method, a casting solution obtained by polymerizing a first unsaturated monomer containing a halogen group with another unsaturated monomer is selected. This method can avoid the use of hazardous chemicals such as chloromethyl ether as a key raw material in the preparation of anionic membranes, thereby achieving higher safety and lower cost, realizing the green production of high-performance anionic membranes, and also realizing precise control of the thickness of the anionic membranes. The method is applied in salt concentration tests of electrodialysis to obtain higher current efficiency and lower unit energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0033] Figure 1 The process flow chart in Example 1 of the present invention is shown. DETAILED DESCRIPTION

[0034] To more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. It should be understood that the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] In addition, unless otherwise specified, the raw materials used in the present invention can be obtained commercially, and any range recorded in the present invention includes the end value and any numerical value between the end values ​​and any sub-range formed by the end value or any numerical value between the end values.

[0036] Example 1

[0037] This example provides a method for preparing anion membrane. See the process flow chart for Figure 1 , the specific steps are as follows:

[0038] S1. Preparation of prepolymer solution: dissolving p-vinylbenzyl chloride, p-divinylbenzene, and azobisisobutyronitrile (AIBN) in NMP at a molar ratio of 1:0.05:0.005:1, and stirring thoroughly.

[0039] S2, prepolymerization reaction: the above prepolymer solution is heated to 45 ° C and polymerized. After 3 hours, the casting solution is obtained;

[0040] S3, coating the casting solution: the casting solution in S2 is smoothly coated on a polyvinyl chloride (PVC) mesh with a thickness of 0.15 mm using a doctor blade;

[0041] S4, film curing: transfer the polyvinyl chloride (PVC) mesh coated with the casting solution into an oven, set the oven temperature to 90°C, and keep it warm for 12 hours;

[0042] S5. Functional modification: After the membrane is completely solidified, the membrane is removed from the equipment and transferred to a 30% triethylamine solution, heated to 45°C, and fully stirred in a closed condition for 24 hours to obtain a functionally modified anion membrane.

[0043] The anionic membrane was used in conjunction with a cationic membrane (purchased from Shandong Tianwei Membrane Technology Co., Ltd., model TWEDC1) to assemble a 4020 electrodialysis membrane stack for salt concentration testing. The effective area of ​​the membrane is 0.05m 2 The number of groups is 4. The cathode and anode are titanium plates with iridium and tantalum oxide coatings. The cathode and anode are connected in series. The electrode liquid is 5% sodium sulfate solution. The concentration of the desalination chamber and the concentration chamber is 5% sodium chloride solution. The operating current is 15A (current density 300A / m 2 ), tested at room temperature (25°C) for 1 hour. The results showed that the anion membrane prepared according to the above scheme had a total thickness of 0.19 mm, an ion exchange capacity of 1.08 mmol / g, and a surface resistance of 4.3 Ω·cm 2 During the electrodialysis membrane component test, the current efficiency was 73.5%, the unit energy consumption was 529.80kwh / t, and the unit processing capacity was 481.32g / (m 2 ·h).

[0044] Example 2

[0045] This example provides a method for preparing an anion membrane, and the specific steps are as follows:

[0046] S1. Preparation of prepolymer solution: dissolving p-vinylbenzyl chloride, p-divinylbenzene, and azobisisobutyronitrile (AIBN) in NMP in a molar ratio of 1:0.08:0.005:1, and stirring thoroughly.

[0047] S2, prepolymerization reaction: the above prepolymer solution is heated to 45 ° C and polymerized. After 3 hours, the casting solution is obtained;

[0048] S3, coating the casting solution: the casting solution in S2 is smoothly coated on a polyvinyl chloride (PVC) mesh with a thickness of 0.15 mm using a doctor blade;

[0049] S4, film curing: transfer the polyvinyl chloride (PVC) mesh coated with the casting solution into an oven, set the oven temperature to 90°C, and keep it warm for 12 hours;

[0050] S5. Functional modification: After the membrane is completely solidified, the membrane is removed from the equipment and transferred to a 30% triethylamine solution, heated to 45°C, and fully stirred in a closed condition for 24 hours to obtain a functionally modified anion membrane.

[0051] The anionic membrane was used in conjunction with a cationic membrane (purchased from Shandong Tianwei Membrane Technology Co., Ltd., model TWEDC1) to assemble a 4020 electrodialysis membrane stack for salt concentration testing. The effective area of ​​the membrane is 0.05m 2 The number of groups is 4. The cathode and anode are titanium plates with iridium and tantalum oxide coatings. The cathode and anode are connected in series. The electrode liquid is 5% sodium sulfate solution. The concentration of the desalination chamber and the concentration chamber is 5% sodium chloride solution. The operating current is 15A (current density 300A / m 2 ), tested at room temperature (25°C) for 1 hour. The results showed that the anion membrane prepared according to the above scheme had a total thickness of 0.23 mm, an ion exchange capacity of 0.89 mol / g, and a surface resistance of 6.1 Ω·cm 2 During the electrodialysis membrane component test, the current efficiency was 63.8%, the unit energy consumption was 660.61kwh / t, and the unit processing capacity was 417.79g / (m 2 ·h).

[0052] Example 3

[0053] This example provides a method for preparing an anion membrane, and the specific steps are as follows:

[0054] S1. Preparation of prepolymer solution: dissolving p-vinylbenzyl chloride, p-divinylbenzene, and azobisisobutyronitrile (AIBN) in NMP at a molar ratio of 1:0.05:0.005:1, and stirring thoroughly.

[0055] S2, prepolymerization reaction: the above prepolymer solution is heated to 45 ° C and polymerized. After 3 hours, the casting solution is obtained;

[0056] S3, coating the casting solution: the casting solution in S2 is smoothly coated on a polyethylene film with a thickness of 0.10 mm using a doctor blade;

[0057] S4, film curing: the polyethylene film coated with the casting solution is transferred to an oven, the oven temperature is set to 90°C, and the temperature is kept for 12 hours;

[0058] S5. Functional modification: After the membrane is completely solidified, the membrane is removed from the equipment and transferred to a 30% triethylamine solution, heated to 45°C, and fully stirred in a closed condition for 24 hours to obtain a functionally modified anion membrane.

[0059] The anionic membrane was used in conjunction with a cationic membrane (purchased from Shandong Tianwei Membrane Technology Co., Ltd., model TWEDC1) to assemble a 4020 electrodialysis membrane stack for salt concentration testing. The effective area of ​​the membrane is 0.05m 2 The number of groups is 4. The cathode and anode are titanium plates with iridium and tantalum oxide coatings. The cathode and anode are connected in series. The electrode liquid is 5% sodium sulfate solution. The concentration of the desalination chamber and the concentration chamber is 5% sodium chloride solution. The operating current is 15A (current density 300A / m 2 ), tested at room temperature (25°C) for 1 hour. The results showed that the anion membrane prepared according to the above scheme had a total thickness of 0.15 mm, an ion exchange capacity of 1.15 mol / g, and a surface resistance of 3.3 Ω·cm 2 During the electrodialysis membrane component test, the current efficiency was 70.2%, the unit energy consumption was 476.39kwh / t, and the unit processing capacity was 459.71g / (m 2 ·h).

[0060] Comparative Example 1

[0061] The anionic membrane TWEDA1 produced by Shandong Tianwei Membrane Technology Co., Ltd. was used as a comparative experiment, and the same conditions were tested as in Example 1. The test data are as follows:

[0062] The anion membrane has a thickness of 0.16 mm, an ion exchange capacity of 1.11 mmol / g, and a surface resistance of 3.6 Ω·cm. 2 During the electrodialysis membrane component test, the current efficiency was 72.3%, the unit energy consumption was 513.35kwh / t, and the unit processing capacity was 473.48g / (m 2 ·h).

[0063] The above tests show that the anion membrane prepared by the present invention has comparable performance to commercially available anion membranes. However, since commercially available anion membranes generally use chloromethyl ether technology, which is more hazardous, the anion membrane prepared by the present invention has outstanding industrial application prospects and social and economic benefits.

[0064] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing an anion membrane, characterized in that: The steps include: S1, prepolymerization: dissolving the first unsaturated monomer containing a halogen group, the second unsaturated monomer and an initiator in an organic solvent, and performing a polymerization reaction after dissolution to obtain a casting solution; S2, solidification: coating the casting solution on the supporting substrate and solidifying it into a film; S3. Functional modification: After the membrane is completely solidified, the membrane is transferred to an organic amine solution and fully reacted under closed conditions to obtain a functionally modified anion membrane; Wherein, the molar ratio of the first unsaturated monomer to the second unsaturated monomer is 1:0.03-0.

10.

2. The preparation method according to claim 1, characterized in that The first unsaturated monomer is selected from one of p-vinylbenzyl chloride, m-vinylbenzyl chloride, p-chlorostyrene, m-chlorostyrene, p-bromostyrene and m-bromostyrene; The second unsaturated monomer is selected from o-divinylbenzene and / or p-divinylbenzene.

3. The preparation method according to claim 1, characterized in that The initiator is selected from one or more of dibenzoyl peroxide, dodecyl peroxide, di-tert-butyl peroxide, tert-butyl perbenzoate, diisopropyl peroxydicarbonate, diethylhexyl peroxydicarbonate, azobisisobutyronitrile, azobisisoheptylonitrile, and tetraethylthiuram; The organic solvent is selected from one or more of tetrahydrofuran, N-methylpyrrolidone, and N,N-dimethylformamide.

4. The preparation method according to claim 1, characterized in that The molar ratio of the first unsaturated monomer to the initiator is 1:0.002-0.

05.

5. The preparation method according to claim 1, characterized in that The polymerization reaction temperature is 40-70° C., and the polymerization reaction time is 1-4 hours.

6. The preparation method according to claim 1, characterized in that The supporting substrate is selected from one of non-woven fabrics, polypropylene mesh, polyvinyl chloride mesh, nylon mesh, polyester mesh, polyetheretherketone mesh, polyethylene film, and polypropylene film, and has a thickness of 0.05 to 0.3 mm.

7. The preparation method according to claim 1, characterized in that The temperature of the curing reaction is 70 to 100° C., and the time of the curing reaction is 12 to 24 hours.

8. The preparation method according to claim 1, characterized in that The concentration of the organic amine solution is 30-60%; The organic amine solution is selected from one or more of trimethylamine solution, triethylamine solution, tripropylamine solution, N,N-dicyclohexylmethylamine, N,N-dimethylaniline, N-propyldicyclohexylamine, N-methyldiethanolamine, and triethanolamine; The reaction temperature of step S3 is 40-60° C., and the reaction time is 12-24 h.

9. An anion membrane, characterized in that The preparation method is described in any one of claims 1 to 8.

10. Use of the anionic membrane as claimed in claim 9 in electrodialysis.

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