A multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane and a preparation method thereof
By introducing aminated multi-walled carbon nanotubes and ferric ions into the hydrogel composite separation membrane, a multi-interpenetrating cross-linked structure is constructed, which solves the problem that the hydrogel self-healing process depends on specific conditions and is limited by swelling. This achieves efficient and stable water filtration performance and mechanical strength, making it suitable for wastewater purification and separation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 天冀桢材科技(河北)有限公司
- Filing Date
- 2024-03-12
- Publication Date
- 2026-07-21
AI Technical Summary
The application of existing hydrogel separation membranes in the field of water filtration is limited by the fact that the self-healing process depends on specific conditions and the swelling capacity is limited, resulting in poor actual performance and insufficient mechanical strength, making them easy to damage.
A three-dimensional flexible network hydrogel composite separation membrane with multiple interpenetrating structures is constructed by introducing aminated multi-walled carbon nanotubes and ferric ions to build a multiple interpenetrating cross-linked structure, which enhances mechanical strength and swelling stability and forms a conductive path.
It maintains high separation performance during long-term use, possesses superior permeability, hydrophilicity, antifouling properties and electrical properties, and can achieve efficient interception and repair under the assistance of an electric field, thus extending its service life.
Smart Images
Figure CN117959961B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of wastewater separation technology, specifically to a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane and its preparation method. Background Technology
[0002] Membrane separation, as a cutting-edge technology for wastewater separation and purification, owes its key advantage to the integrity of its structure. Research has revealed that common organic separation membranes are susceptible to mechanical damage in practical applications, such as stress damage during installation, operation, and maintenance; degradation losses caused by chemical cleaning; and excessive local shear forces resulting from physical cleaning. This compromises their structural integrity, altering the membrane's pore structure, hindering effective separation and purification processes, and significantly impacting the membrane's lifespan.
[0003] Membrane separation technology, as a cutting-edge method in wastewater treatment, owes its core advantage to the integrity of its structure. However, in practical applications, we have found that conventional organic separation membranes often suffer various forms of damage, especially during installation, operation, and maintenance, where mechanical stress damage due to uneven stress is very common. Furthermore, the chemical degradation effect during chemical cleaning can also cause membrane material loss, while excessive localized shear forces during physical cleaning can negatively impact the membrane structure. Once the integrity of the membrane structure is compromised, its pore structure changes, making effective separation and purification impossible and significantly shortening the lifespan of the membrane module. Therefore, maintaining and enhancing the integrity of the membrane structure is crucial to ensuring the efficient and sustained operation of membrane separation technology in wastewater treatment.
[0004] Current membrane monitoring technologies cannot accurately locate damaged areas in membrane systems, nor can they effectively repair them. Therefore, researchers are striving to develop new membrane materials with higher mechanical strength, stronger selectivity, longer lifespan, and lower pollution tendency. Inspired by the self-healing mechanisms developed through the long evolution of plants and animals, researchers hope to create membrane materials that can mimic living systems. When such materials suffer mechanical damage, they can not only restore their original mechanical properties and damaged structure but also repair their impaired separation efficiency. The emergence of self-healing polymer separation materials undoubtedly helps extend the lifespan of separation membranes and alleviate environmental and resource pressures, thus attracting increasing attention from academia and industry. Hydrogels, as self-healing materials, achieve their self-healing process through flexible, dynamic, and reversible covalent and non-covalent bonds. With their unique three-dimensional flexible network structure and physicochemical properties, hydrogels have become important research subjects in biomedicine, soft-drive water purification, intelligent sensing, and optoelectronic devices. However, despite this, the application of hydrogels in water filtration remains limited. The primary issue is that the self-healing process of most hydrogels typically depends on specific conditions, such as specific temperatures, light exposure, pH levels, or the presence of certain chemicals. Secondly, while the swelling properties of hydrogels are crucial for their self-healing and separation / sieving performance, excessive swelling can lead to a significant reduction in membrane permeability, thus limiting their practical application in water filtration.
[0005] Therefore, there is an urgent need for a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane and its preparation method, in order to establish a stable conductive path, optimize the overall structure of the hydrogel, and bring new possibilities to water treatment and separation purification technologies. Summary of the Invention
[0006] To address this issue, the present invention provides a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane and its preparation method, thereby solving the problem that the existing technology suffers from poor practical application in the field of water filtration due to the dependence of the hydrogel's self-healing process on specific conditions and the limitation of swelling.
[0007] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane is provided, comprising a matrix, a base membrane, and a filler, wherein the matrix is polyacrylic acid, the base membrane is polyethersulfone, and the filler is aminated multi-walled carbon nanotubes and ferric ions.
[0008] According to a second aspect of the present invention, a method for preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane is provided, comprising the following steps: S1. Weigh out acrylic monomer, N,N-methylenebisacrylamide and polyethylene glycol respectively and disperse them evenly in deionized water. Add aminated multi-walled carbon nanotubes and disperse them ultrasonically. Then add ammonium persulfate to the dispersed mixed solution and stir at a constant temperature to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution. S2. The aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution prepared in S1 was spin-coated onto a polyethersulfone ultrafiltration membrane, and cross-linked and cured at a constant temperature. After the hydrogel was fully soaked and purified, it was dried in a vacuum oven at 60°C until constant weight, thus preparing an aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite membrane. S3. Take out the aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite film from S2 and immerse it in ferric chloride solution for constant temperature cross-linking and curing to construct a multi-interpenetrating cross-linked three-dimensional network conductive polyacrylic acid gel modified layer structure, namely, iron ion doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite film. S4. The iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane in S3 was placed in deionized water and the water was changed every 1-24 hours until the quality was stable. Finally, it was placed in a constant temperature vacuum oven to dry to constant weight, thus preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
[0009] Furthermore, in S1, the amount of acrylic acid monomer added is 0-20g, the amount of N,N-methylenebisacrylamide added is 0-0.5g, and the amount of polyethylene glycol added is 0-20g, which are uniformly dispersed in 40mL of deionized water.
[0010] Furthermore, the aminated multi-walled carbon nanotubes used have a purity >97%, an outer diameter of 3-15 nm, a length of 15-30 μm, and a polyacrylic acid purity >99%. N,N-methylenebisacrylamide, ammonium persulfate, and ferric chloride hexahydrate are AR grade powders.
[0011] Furthermore, in S1, the concentration of added aminated multi-walled carbon nanotubes is 0-5 mg / mL, and the nanotubes are ultrasonically dispersed at 0-200 W for 0-5 h.
[0012] Furthermore, in S1, the amount of ammonium persulfate added to the mixed solution is 0-0.5g, the temperature of constant temperature stirring is 0-100℃, and the stirring time is 0-2h.
[0013] Furthermore, in S2, the spin-coating amount of the aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution is 1-20 mL, and the polyethersulfone ultrafiltration membrane is prepared by impregnation phase inversion method.
[0014] Furthermore, the cross-linking curing temperature in S2 is 20-100℃, and the time is 0-24h.
[0015] Furthermore, in step S3, the concentration of the ferric chloride solution is 0-0.1 mol / L, the soaking time is 0-24 h, and the cross-linking curing temperature is 0-100 °C.
[0016] The present invention also provides the application of the multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane described in any one of the above technical solutions or the composite separation membrane prepared by the preparation method described in any one of the above technical solutions in wastewater purification.
[0017] The present invention has the following advantages: 1. This application significantly enhances the mechanical strength and swelling stability of polyacrylic acid hydrogels by introducing aminated multi-walled carbon nanotubes into the hydrogel system. On the one hand, the introduction of carbon nanotubes enhances the mechanical properties of the hydrogel network; on the other hand, the coordination linkage formed by the acid-amine condensation reaction between amino and carboxylic acid groups improves the dimensional stability and swelling resistance of the hydrogel under long-term immersion, resulting in superior performance during long-term use.
[0018] 2. This application uses aminated multi-walled carbon nanotubes modified with ferric chloride solution to modify a three-dimensional composite membrane of polyacrylic acid / polyethersulfone. Through the chelation of ferric ions with the polyacrylic acid hydrogel network, a polyacrylic acid hydrogel composite separation membrane with a multi-interpenetrating three-dimensional network structure with long-term stable swelling performance is constructed. The membrane exhibits excellent stability and maintains high-efficiency separation performance in a 100-day immersion test.
[0019] 3. The polyacrylic acid hydrogel composite separation membrane with a multi-interpenetrating three-dimensional network structure prepared by spin coating in this application has superior permeability, hydrophilicity, antifouling and electrical properties, and is suitable for various application environments. In addition to significantly improved mechanical properties, the polyacrylic acid hydrogel composite separation membrane with a multi-interpenetrating three-dimensional network structure also exhibits electrical-assisted repair performance, and can achieve a retention recovery rate of more than 90% for methylene blue dye solution under a 3V auxiliary voltage, demonstrating good recycling and repair capabilities. Attached Figure Description
[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.
[0021] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.
[0022] Figure 1 A schematic diagram of the multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane provided by the present invention; Figure 2 The test results of the long-term swelling ratio of the hydrogel composite separation membrane provided by the present invention; Figure 3 A schematic diagram comparing the mechanical strength of different hydrogel composites provided by this invention; Figure 4 A schematic diagram comparing the electric field-assisted methylene blue staining solution retention and repair performance of different hydrogel composite separation membranes provided by the present invention. Detailed Implementation
[0023] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0024] This invention provides a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane, comprising a matrix, a base membrane, and fillers. The matrix is polyacrylic acid (PAA), the base membrane is polyethersulfone (PES), and the fillers are aminated multi-walled carbon nanotubes (CNTs-NH2) and ferric ions (Fe2+). 3+ ).
[0025] This invention also provides a method for preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane, comprising the following steps: S1. Weigh out acrylic acid monomer (AA), N,N-methylenebisacrylamide (BIS) and polyethylene glycol (PEG-800) and disperse them evenly in deionized water. Add aminated multi-walled carbon nanotubes (CNTs-NH2) and disperse them ultrasonically. Then add ammonium persulfate (APS) to the dispersed mixed solution and stir at a constant temperature to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid (CNTs-NH2 / PAA) hydrogel precursor solution. S2. The aminated multi-walled carbon nanotube modified polyacrylic acid (CNTs-NH2 / PAA) hydrogel precursor solution prepared in S1 was spin-coated onto a polyethersulfone (PES) ultrafiltration membrane and cross-linked and cured at a constant temperature. After the hydrogel was fully soaked and purified, it was dried in a vacuum oven at 60℃ until constant weight to prepare an aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone (CNTs-NH2 / PAA / PES) three-dimensional composite membrane. S3. The aminated multi-walled carbon nanotube-modified polyacrylic acid / polyethersulfone (CNTs-NH2 / PAA / PES) three-dimensional composite film from S2 is removed and immersed in ferric chloride (FeCl3) solution for isothermal crosslinking and curing to construct a multi-interpenetrating crosslinked three-dimensional network conductive polyacrylic acid (PAA) gel modification layer structure, namely, iron ion-doped carbon nanotube aminated polyacrylic acid-polyethersulfone (FeCl3) composite film. 3+ (CNTs-NH2 / PAA / PES) multi-interpenetrating three-dimensional network composite membrane; S4. Amide-modified polyacrylate-polyethersulfone (Fe3O4) from iron-doped carbon nanotubes in S3. 3+ The CNTs-NH2 / PAA / PES multi-interpenetrating three-dimensional network composite membrane was placed in deionized water, and the water was changed every 1-24 hours until the quality stabilized. Finally, it was placed in a constant temperature vacuum oven to dry to constant weight, thus preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
[0026] Specifically, in S1, the amount of acrylic acid monomer (AA) added is 0-20g, the amount of N,N-methylenebisacrylamide (BIS) added is 0-0.5g, and the amount of polyethylene glycol (PEG-800) added is 0-20g, which are uniformly dispersed in 40mL of deionized water.
[0027] Specifically, the aminated multi-walled carbon nanotubes (CNTs-NH2) used have a purity >97%, an outer diameter of 3-15 nm, a length of 15-30 μm, and a polyacrylic acid (PAA) purity >99%. N,N-methylenebisacrylamide (BIS), ammonium persulfate (APS), and ferric chloride hexahydrate (FeCl3·6H2O) are AR grade powders.
[0028] Specifically, in S1, the concentration of aminated multi-walled carbon nanotubes (CNTs-NH2) added is 0-5 mg / mL, and it is ultrasonically dispersed at 0-200 W for 0-5 h.
[0029] Specifically, the amount of ammonium persulfate (APS) added to the mixed solution in S1 is 0-0.5g, the temperature of constant temperature stirring is 0-100℃, and the stirring time is 0-2h.
[0030] In particular, the spin-coating amount of the polyacrylic acid (CNTs-NH2 / PAA) hydrogel precursor solution modified with aminated multi-walled carbon nanotubes in S2 is 1-20 mL, and the polyether sulfone (PES) ultrafiltration membrane is prepared by impregnation phase inversion method.
[0031] Specifically, the cross-linking curing temperature in S2 is 20-100℃, and the time is 0-24h.
[0032] Specifically, the concentration of ferric chloride (FeCl3) solution in S3 is 0-0.1 mol / L, the soaking time is 0-24 h, and the cross-linking curing temperature is 0-100℃.
[0033] Specifically, the ferric chloride (FeCl3) solution is prepared by mixing ferric chloride hexahydrate (FeCl3·6H2O) and deionized water.
[0034] The present invention also provides the application of the multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane of any one of the above technical solutions or the composite separation membrane prepared by any one of the above technical solutions in wastewater purification.
[0035] Example 1 This embodiment provides a method for preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane, including the following steps: S1: Weigh 12g of acrylic monomer, 0.12g of crosslinking agent N,N-methylenebisacrylamide and 10g of polyethylene glycol, respectively, disperse them in 40mL of deionized water, stir at 60℃ for 1h, add aminated multi-walled carbon nanotubes to prepare a solution with a concentration of 0.5mg / mL, sonicate at 180W for 1h, then add 0.12g of ammonium persulfate initiator to the well dispersed mixture, react at 60℃ for 1h to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution.
[0036] S2: Take 10 mL of the aminated multi-walled carbon nanotube-modified polyacrylic acid hydrogel precursor solution prepared in S1 and spin-coat it uniformly onto the polyethersulfone ultrafiltration membrane. Incubate at 60°C for 6 hours for crosslinking and curing. After thoroughly immersing and purifying the hydrogel, dry it in a vacuum oven at 60°C to constant weight to obtain the aminated multi-walled carbon nanotube-modified polyacrylic acid / polyethersulfone three-dimensional composite membrane.
[0037] S3: The aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite film from S2 was taken out and immersed in 0.06 mol / L ferric chloride solution at 25℃ for 12 h to construct a multi-interpenetrating cross-linked three-dimensional network conductive polyacrylic acid gel modified layer structure, namely, iron ion doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite film.
[0038] S4: The iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane in S3 was immersed in deionized water, and the water was changed every 24 hours until the quality was stable. After it was fully purified, it was dried in a vacuum oven at 60℃ to constant weight to prepare a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
[0039] Example 2 This embodiment provides a method for preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane, including the following steps: S1: Weigh 12g of acrylic acid monomer, 0.12g of crosslinking agent N,N-methylenebisacrylamide, and 10g of polyethylene glycol, and disperse them in 40mL of deionized water. After stirring at 60℃ for 1h, add aminated multi-walled carbon nanotubes to prepare a solution with a concentration of 1mg / mL. Sonicate the solution at 180W for 1h. Then add 0.12g of ammonium persulfate initiator to the well-dispersed mixture and react at 60℃ for 1h to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution.
[0040] S2: Take 10 mL of the aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution prepared in S1 and spin-coat it uniformly onto the polyethersulfone ultrafiltration membrane. Incubate at 60℃ for 6 hours for crosslinking and curing. After thoroughly immersing and purifying the hydrogel, dry it in a vacuum oven at 60℃ until constant weight to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite membrane.
[0041] S3: The aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite film from S2 was taken out and immersed in a 0.06 mol / L ferric chloride solution at 25℃ for 12 h to construct a multi-interpenetrating cross-linked three-dimensional network conductive polyacrylic acid gel modified layer structure, namely, iron ion doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite film.
[0042] S4: The iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane in S3 was immersed in deionized water, and the water was changed every 12 hours until the quality was stable. After it was fully purified, it was dried in a 60℃ constant temperature vacuum oven to constant weight to prepare a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
[0043] Example 3 This embodiment provides a method for preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane, including the following steps: S1: Weigh 12g of acrylic acid monomer, 0.12g of crosslinking agent N,N-methylenebisacrylamide, and 10g of polyethylene glycol and disperse them in 40mL of deionized water. After stirring at 60℃ for 1h, add aminated multi-walled carbon nanotubes to prepare a solution with a concentration of 0.25 mg / mL. Sonicate the solution at 180W for 1h. Then add 0.12g of ammonium persulfate to the well-dispersed mixture and react at 60℃ for 1h to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution. S2: Take 10 mL of the aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution prepared in S1 and spin-coat it evenly on the polyethersulfone ultrafiltration membrane. Crosslink and cure the membrane at 60℃ for 6 h. After fully immersing and purifying the hydrogel, dry it in a vacuum oven at 60℃ until constant weight to prepare an aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite membrane. S3: Take out the aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite film from S2 and soak it in 0.06 mol / L ferric chloride solution at 25℃ for 12 h to construct a multi-interpenetrating cross-linked three-dimensional network conductive polyacrylic acid gel modified layer structure, namely iron ion doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite film. S4: The iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane in S3 was immersed in deionized water, and the water was changed every 8 hours until the quality was stable. After it was fully purified, it was dried in a vacuum oven at 60℃ to constant weight to prepare a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
[0044] The finished multi-interpenetrating three-dimensional flexible network hydrogel composite separation membranes prepared in Examples 1-3 were subjected to relevant tests, and the results are as follows: Figure 1-4 As shown.
[0045] Summarize: 1. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membranes obtained in Examples 1-3 include a polyethersulfone-based membrane and an iron-doped carbon nanotube aminated polyacrylic acid-polyethersulfone hydrogel modification layer, such as... Figure 1 As shown, based on the in-situ polymerization of polyacrylic acid, aminated multi-walled carbon nanotubes and trivalent iron ions are incorporated into the three-dimensional flexible gel network of polyacrylic acid to obtain a modified conductive polyacrylic acid hydrogel layer with a multi-interpenetrating structure.
[0046] 2. By comparing the long-term swelling performance of different hydrogel composite separation membranes in aqueous solution, it was found that the long-term stability of the iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-penetrating three-dimensional network composite membrane was superior after introducing an aminated multi-walled carbon nanotube and a three-dimensional flexible interpenetrating network of ferric ions. It maintained swelling stability even after 100 days of immersion. Figure 2 As shown, this solves the problem of poor long-term swelling stability of common hydrogel networks in water.
[0047] 3. Through Figure 3 The comparison of mechanical strength of different hydrogel composite separations shows that the polyacrylic acid / polyethersulfone hydrogel composite separation membrane with the introduction of aminated multi-walled carbon nanotubes and trivalent iron ions has excellent mechanical properties, and can achieve high elongation at break and mechanical strength. The mechanical strength and elongation at break of the iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane can reach about twice that of the unmodified polyethersulfone membrane, effectively avoiding the problem of damage to the integrity of the membrane structure.
[0048] 4. Through Figure 4 Electric field-assisted remediation data of hydrogel composite separation membranes revealed that iron-doped carbon nanotube-aminated polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membranes exhibit certain electric field-assisted remediation performance under electric field assistance. The concentration of methylene blue dye in the feed and filtrate at 664 nm was measured using a UV spectrophotometer. The results showed that the iron-doped carbon nanotube-aminated polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane demonstrated high separation and purification performance in treating methylene blue dye, effectively retaining the dye, and maintaining a retention efficiency of over 90% even after multiple cycles. This indicates that this composite membrane material possesses excellent stability and regeneration capabilities, showing potential application value in wastewater treatment, dye separation and recovery, and especially in electro-driven membrane separation technology, where the electric field significantly enhances the removal efficiency of specific pollutants.
[0049] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A three-dimensional flexible network hydrogel composite separation membrane with multiple interpenetrating layers, characterized in that, It includes a matrix, a base film, and fillers, wherein the matrix is polyacrylic acid, the base film is polyethersulfone, and the fillers are aminated multi-walled carbon nanotubes and ferric ions; The preparation method of the multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane includes the following steps: S1. Weigh out acrylic monomer, N,N-methylenebisacrylamide and polyethylene glycol respectively and disperse them evenly in deionized water. Add aminated multi-walled carbon nanotubes and disperse them ultrasonically. Then add ammonium persulfate to the dispersed mixed solution and stir at a constant temperature to obtain an aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution. S2. The aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution prepared in S1 was spin-coated onto a polyethersulfone ultrafiltration membrane, and cross-linked and cured at a constant temperature. After the hydrogel was fully soaked and purified, it was dried in a vacuum oven at 60°C until constant weight, thus preparing an aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite membrane. S3. Take out the aminated multi-walled carbon nanotube modified polyacrylic acid / polyethersulfone three-dimensional composite film from S2 and immerse it in ferric chloride solution for constant temperature cross-linking and curing to construct a multi-interpenetrating cross-linked three-dimensional network conductive polyacrylic acid gel modified layer structure, namely, iron ion doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite film. S4. The iron ion-doped carbon nanotube aminated modified polyacrylic acid-polyethersulfone multi-interpenetrating three-dimensional network composite membrane in S3 was placed in deionized water and the water was changed every 1-24 hours until the quality was stable. Finally, it was placed in a constant temperature vacuum oven to dry to constant weight, thus preparing a multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane.
2. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, The amount of acrylic acid monomer added in S1 is 0-20g, the amount of N,N-methylenebisacrylamide added is 0-0.5g, and the amount of polyethylene glycol added is 0-20g, which are uniformly dispersed in 40mL of deionized water.
3. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, The aminated multi-walled carbon nanotubes used have a purity >97%, an outer diameter of 3-15 nm, a length of 15-30 μm, and a polyacrylic acid purity >99%. N,N-methylenebisacrylamide, ammonium persulfate, and ferric chloride hexahydrate are AR grade powders.
4. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, In S1, the concentration of aminated multi-walled carbon nanotubes added is 0-5 mg / mL, and the nanotubes are ultrasonically dispersed at 0-200 W for 0-5 h.
5. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, In step S1, the amount of ammonium persulfate added to the mixed solution is 0-0.5g, the temperature of constant temperature stirring is 0-100℃, and the stirring time is 0-2h.
6. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, In S2, the spin-coating amount of the aminated multi-walled carbon nanotube modified polyacrylic acid hydrogel precursor solution is 1-20 mL, and the polyethersulfone ultrafiltration membrane is prepared by impregnation phase inversion method.
7. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, The cross-linking and curing temperature in S2 is 20-100℃, and the time is 0-24h.
8. The multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane as described in claim 1, characterized in that, In step S3, the concentration of the ferric chloride solution is 0-0.1 mol / L, the soaking time is 0-24 h, and the cross-linking curing temperature is 0-100℃.
9. The application of the multi-interpenetrating three-dimensional flexible network hydrogel composite separation membrane according to any one of claims 1-8 in wastewater purification.