Composite antifouling adsorbing membrane and use thereof

Abstract

The application relates to a composite anti-fouling adsorption membrane and an application thereof, and belongs to the technical field of separation composite membranes. The application comprises the following steps: 1) dissolving carboxylated polyvinylidene fluoride, carboxymethyl chitosan and a pore-forming agent polyethylene glycol in a solvent, stirring and mixing, and vacuum degassing to obtain a casting solution; 2) pouring the casting solution on a glass plate to form a thick liquid film, immersing the thick liquid film into a coagulation bath to solidify into a film, and immersing the film into a pure water bath to obtain a wet film; 3) immersing the wet film into an acrylic acid solution containing a photoinitiator, performing a free radical polymerization reaction under the protection of nitrogen and through ultraviolet light irradiation to obtain a hydrophilic acrylic coating, then washing the coating with deionized water, and vacuum drying to obtain the composite anti-fouling adsorption membrane. The membrane has gradient pores, good mechanical properties and hydrophilicity, the preparation process is simple, the adsorption rate is fast, the adsorption capacity is high, the regeneration life is long, and the membrane has strong practicability.

Description

Technical Field

[0001] This invention belongs to the field of membrane separation technology, specifically a composite antifouling adsorption membrane and its applications. Background Technology

[0002] With increasingly stringent environmental regulations (such as the "Water Pollution Prevention and Control Action Plan" requiring heavy metal emission concentrations ≤0.1mg / L), the deep removal of trace heavy metals (μg / L-mg / L level) from industrial wastewater has become a technical challenge. Traditional adsorption materials (such as activated carbon and ion exchange resins) suffer from bottlenecks such as slow adsorption kinetics, poor selectivity, and low regeneration efficiency at low concentrations. For example: Activated carbon: The adsorption capacity for trace Pb²⁺ (<1mg / L) is less than 20mg / g, and it is easily interfered with by organic matter such as humic acid. Ion exchange resins: Frequent regeneration is required (the exchange capacity decreases by 50% after 3-5 cycles), resulting in high-salinity wastewater. Conventional polymer membranes: Hydrophobic PVDF membranes (contact angle >110°) suffer from flux attenuation rates >60% due to surface fouling, making them unable to stably treat low-concentration wastewater. Existing patented technologies (such as CN113041979A using chitosan coating modification) improve hydrophilicity, but face two major technical defects: Insufficient adsorption selectivity: Coexisting ions (Ca 2+ Na + When the concentration is 100 times higher than the target heavy metal, the removal rate of Pb²⁺ drops sharply to <70%; the trace adsorption kinetics are poor: the adsorption equilibrium time for 50 μg / L Cd²⁺ is >4 hours, which cannot meet the requirements for continuous treatment. Summary of the Invention

[0003] To address the aforementioned problems in the existing technology, the present invention aims to design and provide a technical solution for a composite antifouling adsorption membrane and its applications. This membrane combines high adsorption capacity, excellent mechanical strength, and hydrophilic antifouling properties to achieve a coupled adsorption and filtration effect, simultaneously treating micro-pollutants and trace heavy metals in water. Furthermore, the grafted polyacrylic acid coating gives the membrane excellent resistance to protein fouling, meeting the requirements for continuous treatment.

[0004] The composite antifouling adsorption membrane is characterized by being prepared using the following method: 1) Preparation of casting solution: At 75-85℃, add 15-20 wt% carboxylated polyvinylidene fluoride, 0.1-1 wt% carboxymethyl chitosan and 5-15 wt% pore-forming agent to a 64-79.9 wt% N,N-dimethylacetamide solution and stir evenly for 5-7 hours to obtain the casting solution; 2) Film scraping and phase inversion: After centrifuging and degassing the casting solution, it is poured onto a glass plate and scraped into a thick liquid film. The film is then immersed in a coagulation bath to solidify into a film, and then transferred to deionized water for soaking and washing to obtain a wet film. 3) UV grafting modification: The wet film is immersed in an acrylic acid solution containing a photoinitiator and subjected to free radical polymerization under nitrogen protection by UV irradiation to obtain a hydrophilic acrylic coating. After soaking and washing with deionized water until pH=7, and vacuum drying, a composite antifouling adsorption membrane is obtained.

[0005] The composite antifouling adsorption membrane is characterized in that, in step 1), 16-18 wt% carboxylated polyvinylidene fluoride, 0.4-0.6 wt% carboxymethyl chitosan, 8-12 wt% pore-forming agent, and N,N-dimethylacetamide solution is used as a solvent to make up to 100%.

[0006] The composite antifouling adsorption membrane is characterized in that, in step 1), the carboxylated polyvinylidene fluoride resin has a weight-average molecular weight of 400,000 to 700,000, and is selected from at least one of powder, granules, and flakes, preferably with a molecular weight range of 500,000 to 600,000; the carboxyl content of the carboxylated polyvinylidene fluoride is 1.5-3.0 mmol / g, preferably 2-2.5 mmol / g.

[0007] The composite antifouling adsorption membrane is characterized in that, in step 1), the pore-forming agent is at least one of polyethylene glycol 2000, polyethylene glycol 6000, polyethylene glycol 4000, and polyethylene glycol 8000.

[0008] The composite antifouling adsorption membrane is characterized in that, in step 1), the N,N-dimethylacetamide solution contains 4-6 wt% lithium chloride.

[0009] The composite antifouling adsorption membrane is characterized in that, in step 2), the thickness of the thick liquid film is 250-350 μm.

[0010] The composite antifouling adsorption membrane is characterized in that, in step 2), the coagulation bath is an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride, the temperature of the coagulation bath is 20℃-60℃, preferably 30℃-50℃, and the curing time is 8-12 minutes.

[0011] The composite antifouling adsorption membrane is characterized in that, in step 3), the concentration of the polyacrylic acid aqueous solution is 5-10 wt%, preferably 6-8 wt%, and the pH is 4.0; the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and the addition amount is 0.05-0.2 wt%, preferably 0.1-0.15 wt%.

[0012] The composite anti-fouling adsorption membrane is characterized in that, in step 3), the intensity of the ultraviolet lamp is 80-120 mW / cm², and the irradiation time is 8-12 minutes.

[0013] The composite antifouling adsorption membrane described above is used in the field of water treatment, especially in the preparation of ultrapure water in the electronics industry, the remediation of drinking water sources, and the treatment of radioactive wastewater from nuclear power plants.

[0014] This invention addresses the problem of deep removal of trace heavy metals from industrial wastewater. Based on solvent-induced phase separation and surface modification technology, it utilizes multi-factor synergistic regulation of membrane structure and surface functional groups to prepare a composite antifouling adsorption membrane. The preparation conditions significantly influence the thermodynamic and kinetic behavior during membrane formation, thus determining the membrane's microstructure and macroscopic properties. First, the concentration of polyvinylidene fluoride (PVDF) emulsion is fundamental to the membrane's mechanical strength and porosity. Building upon this, carboxymethyl chitosan and polyethylene glycol are introduced as multifunctional additives: carboxymethyl chitosan regulates the membrane surface's hydrophilicity and compatibility with PVDF through its carboxyl group content and degree of substitution, achieving uniform modification; polyethylene glycol acts as a pore-forming agent due to its molecular weight, particularly employing a dual-molecular-weight polyethylene glycol strategy to construct a interconnected heterogeneous structure of surface micropores and internal mesopores, greatly improving mass transfer efficiency. Finally, polyacrylic acid is grafted onto the membrane surface using ultraviolet light to construct a hydrophilic negatively charged layer, further enhancing antifouling and electrostatic properties. Through the above synergistic effect, the overall optimization of membrane pore size distribution, pore connectivity, surface functional groups and mechanical strength is achieved.

[0015] This invention achieves breakthroughs in three major technical challenges of trace heavy metal adsorption through multi-scale structural design and synergistic effects of functional groups: First, by combining gradient pore design with surface charge pre-enrichment, rapid adsorption of ultra-low concentrations (µg / L) of heavy metals is realized (equilibrium time ≤30 minutes); second, through multi-coordination and size sieving coupling, dual physical-chemical selectivity is achieved; finally, by combining a highly hydrophilic antifouling layer with in-situ acid regeneration technology, the antifouling performance and regeneration life of the membrane material are significantly improved. This membrane is specifically designed for complex scenarios such as ultrapure water in the electronics industry, drinking water source remediation, and radioactive wastewater, solving the three major industry problems of slow kinetics, poor selectivity, and short regeneration life of traditional adsorption materials, while reducing operation and maintenance costs by 80%.

[0016] The aforementioned composite antifouling adsorption membrane possesses high porosity and strong charge, combining the dual functions of adsorption and filtration. Furthermore, the highly hydrophilic carboxymethyl chitosan (CMCS) and polyacrylic acid (PAA) endow the membrane with excellent antifouling properties. Compared to traditional adsorption membrane materials that rely on embedded adsorbents, this composite adsorption membrane, through covalent reaction-based surface coating modification, significantly improves its long-term stability and extends the membrane's lifespan. The composite membrane preparation method described in this invention is simple, suitable for large-scale production, and has broad application prospects in fields such as ultrapure water in the electronics industry and drinking water purification. Detailed Implementation

[0017] The technical solution of the present invention will be clearly described below through corresponding embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0018] (1) At 80°C, 15 wt% carboxylated polyvinylidene fluoride, 0.1 wt% carboxymethyl chitosan, and 5 wt% polyethylene glycol 8000 were added to a 79.9 wt% N,N-dimethylacetamide solution and stirred uniformly for 6 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of polyvinylidene fluoride were 700,000 and 1.5 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 4 wt% lithium chloride.

[0019] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film with a thickness of 350 micrometers. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 20℃ and the solidification time is 8 minutes. Then, soak and wash it in 40℃ deionized water for 24 hours to obtain a wet film.

[0020] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.05 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 5 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 80 mW / cm² ultraviolet light for 8 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane. Example 2

[0021] (1) At 75°C, 20 wt% carboxylated polyvinylidene fluoride, 1 wt% carboxymethyl chitosan, and 15 wt% polyethylene glycol 2000 were added to a 64 wt% N,N-dimethylacetamide solution and stirred uniformly for 5 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of polyvinylidene fluoride were 400,000 and 3 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 6 wt% lithium chloride.

[0022] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film with a thickness of 250 micrometers. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 60℃ and the solidification time is 12 minutes. Then, soak and wash it in 35℃ deionized water for 26 hours to obtain a wet film.

[0023] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.2 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 10 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 120 mW / cm² ultraviolet light for 12 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane. Example 3

[0024] (1) At 85°C, 16 wt% carboxylated polyvinylidene fluoride, 0.5 wt% carboxymethyl chitosan, and 10 wt% polyethylene glycol 4000 were added to a 64 wt% N,N-dimethylacetamide solution and stirred uniformly for 7 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of the polyvinylidene fluoride were 600,000 and 2 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 5 wt% lithium chloride.

[0025] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film 300 micrometers thick. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 40℃ and the solidification time is 8 minutes. Then, soak and wash it in 45℃ deionized water for 22 hours to obtain a wet film.

[0026] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.1 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 8 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 100 mW / cm² ultraviolet light for 8 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane. Example 4

[0027] (1) At 80°C, 19 wt% carboxylated polyvinylidene fluoride, 0.75 wt% carboxymethyl chitosan, 6 wt% polyethylene glycol 2000, and 6 wt% polyethylene glycol 6000 were added to a 68.25 wt% N,N-dimethylacetamide solution and stirred uniformly for 6 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of polyvinylidene fluoride were 500,000 and 2.5 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 5.5 wt% lithium chloride.

[0028] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film with a thickness of 325 micrometers. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 50℃ and the solidification time is 10 minutes. Then, soak and wash it in 40℃ deionized water for 24 hours to obtain a wet film.

[0029] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.15 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 9 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 90 mW / cm² ultraviolet light for 12 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane. Example 5

[0030] (1) At 80°C, 18 wt% carboxylated polyvinylidene fluoride, 0.85 wt% carboxymethyl chitosan, 8 wt% polyethylene glycol 4000, and 5 wt% polyethylene glycol 8000 were added to a 68.15 wt% N,N-dimethylacetamide solution and stirred uniformly for 6 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of polyvinylidene fluoride were 550,000 and 2.8 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 4.5 wt% lithium chloride.

[0031] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film with a thickness of 275 micrometers. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 55℃ and the solidification time is 8 minutes. Then, soak and wash it in 40℃ deionized water for 24 hours to obtain a wet film.

[0032] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.12 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 8 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 85 mW / cm² ultraviolet light for 9 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane. Example 6

[0033] (1) At 80°C, 17 wt% carboxylated polyvinylidene fluoride, 0.95 wt% carboxymethyl chitosan, 9 wt% polyethylene glycol 2000, and 4 wt% polyethylene glycol 8000 were added to a 68.15 wt% N,N-dimethylacetamide solution and stirred uniformly for 6 hours to obtain a casting solution. The weight-average molecular weight and carboxyl content of polyvinylidene fluoride were 650,000 and 2.4 mmol / g, respectively, and the N,N-dimethylacetamide solution contained 4.8 wt% lithium chloride.

[0034] (2) After centrifuging and degassing the prepared casting solution, pour it onto a glass plate and scrape it into a liquid film with a thickness of 290 micrometers. Immerse it in an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride to solidify it into a film. The temperature of the coagulation bath is 45℃ and the solidification time is 10 minutes. Then, soak and wash it in 40℃ deionized water for 24 hours to obtain a wet film.

[0035] (3) The obtained wet membrane was immersed in an acrylic acid solution containing 0.17 wt% 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, the concentration of acrylic acid in water was 7 wt%, and the pH was 4. Further, under nitrogen protection, it was irradiated with 75 mW / cm² ultraviolet light for 8 minutes to induce a free radical polymerization reaction to obtain a hydrophilic polyacrylic acid coating. After that, it was soaked and washed with deionized water until the pH was 7, and then vacuum dried at 40°C to obtain a composite antifouling adsorption membrane.

[0036] The composite antifouling adsorption membranes prepared in Examples 1-6 were used. Six portions of 50 μg / L Cu were prepared. 2+ The solution was prepared, and the filtration pressure was set to 0.2 MPa.

[0037] The composite antifouling adsorption membrane Cu prepared in Example 1 2+ The adsorption capacity was 172.5 mg / g, and the flux was 57.1 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 91%, and it maintained 87% of its adsorption capacity after ten cycles.

[0038] The composite antifouling adsorption membrane Cu prepared in Example 2 2+ The adsorption capacity was 155.3 mg / g, and the flux was 68.4 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 90%, and it maintained 83% of its adsorption capacity after ten cycles.

[0039] The composite antifouling adsorption membrane Cu prepared in Example 3 2+ The adsorption capacity was 167.1 mg / g, and the flux was 42.9 L·m⁻². -2 ·h-1 After a 120-minute BSA filtration test, its flux recovery rate was 92%, and it maintained 85% of its adsorption capacity after ten cycles.

[0040] Organic film Cu prepared in Example 4 2+ The adsorption capacity was 168.3 mg / g, and the flux was 55.6 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 80%, and it maintained 75% of its adsorption capacity after ten cycles.

[0041] Organic film Cu prepared in Example 5 2+ The adsorption capacity was 127.5 mg / g, and the flux was 24.2 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 74%, and it maintained 80% of its adsorption capacity after ten cycles.

[0042] Organic film Cu prepared in Example 6 2+ The adsorption capacity was 120.4 mg / g, and the flux was 25.1 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 76%, and it maintained 82% of its adsorption capacity after ten cycles.

[0043] Prepare 6 portions of 50 μg / L Pb 2+ The solution was prepared, and the filtration pressure was set to 0.15 MPa.

[0044] Pb of the composite antifouling adsorption membrane prepared in Example 1 2+ The adsorption capacity was 179.4 mg / g, and the flux was 56.3 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 89%.

[0045] Pb of the composite antifouling adsorption membrane prepared in Example 2 2+ The adsorption capacity was 162.2 mg / g, and the flux was 65.1 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 90%.

[0046] Pb of the composite antifouling adsorption membrane prepared in Example 3 2+ The adsorption capacity was 169.7 mg / g, and the flux was 40.3 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 88%.

[0047] Pb of the organic membrane prepared in Example 4 2+ The adsorption capacity was 150.3 mg / g, and the flux was 52.3 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 70%.

[0048] Organic membrane As prepared in Example 5 3+ The adsorption capacity was 135.7 mg / g, and the flux was 28.4 L·m⁻². -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 78%.

[0049] Organic membrane Pb prepared in Example 6 2+ The adsorption capacity was 130.8 mg / g, and the flux was 30.0 L·m⁻¹. -2 ·h -1 After a 120-minute BSA filtration test, its flux recovery rate was 73%.

[0050] The experimental data above show that the composite antifouling adsorption membrane prepared by this invention can effectively solve the three major industry problems of slow kinetics, poor selectivity and short regeneration life of traditional adsorption materials, and can efficiently achieve deep removal of trace heavy metals (μg / L-mg / L level), providing a potential option for the preparation of ultrapure water in the electronics industry, the remediation of drinking water sources and the treatment of radioactive wastewater in nuclear power plants.

[0051] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A composite antifouling adsorption membrane, characterized in that... Prepared using the following method: 1) Preparation of casting solution: At 75-85℃, add 15-20 wt% carboxylated polyvinylidene fluoride, 0.1-1 wt% carboxymethyl chitosan and 5-15 wt% pore-forming agent to a 64-79.9 wt% N,N-dimethylacetamide solution and stir evenly for 5-7 hours to obtain the casting solution; 2) Film scraping and phase inversion: After centrifuging and degassing the casting solution, it is poured onto a glass plate and scraped into a thick liquid film. The film is then immersed in a coagulation bath to solidify into a film, and then transferred to deionized water for soaking and washing to obtain a wet film. 3) UV grafting modification: The wet film is immersed in an acrylic acid solution containing a photoinitiator and subjected to free radical polymerization under nitrogen protection by UV irradiation to obtain a hydrophilic acrylic coating. After soaking and washing with deionized water until pH=7, and vacuum drying, a composite antifouling adsorption membrane is obtained.

2. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 1): 16-18 wt% carboxylated polyvinylidene fluoride, 0.4-0.6 wt% carboxymethyl chitosan, 8-12 wt% porogen, and N,N-dimethylacetamide solution as solvent to make up to 100%.

3. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 1): the carboxylated polyvinylidene fluoride resin has a weight-average molecular weight of 400,000 to 700,000, and is selected from at least one of powder, granules, and flakes, with a preferred molecular weight range of 500,000 to 600,000; the carboxyl content of the carboxylated polyvinylidene fluoride is 1.5-3.0 mmol / g, preferably 2-2.5 mmol / g.

4. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 1), the pore-forming agent is at least one of polyethylene glycol 2000, polyethylene glycol 6000, polyethylene glycol 4000, and polyethylene glycol 8000.

5. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 1): the N,N-dimethylacetamide solution contains 4-6 wt% lithium chloride.

6. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 2): the thickness of the thick liquid film is 250-350 μm.

7. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 2): the coagulation bath is an aqueous solution containing 20wt% ethanol and 0.3wt% calcium chloride, the temperature of the coagulation bath is 20℃-60℃, preferably 30℃-50℃; the curing time is 8-12 minutes.

8. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 3): the concentration of the polyacrylic acid aqueous solution is 5-10 wt%, preferably 6-8 wt%, and the pH is 4.0; the photoinitiator is 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and the addition amount is 0.05-0.2 wt%, preferably 0.1-0.15 wt%.

9. The composite antifouling adsorption membrane as described in claim 1, characterized in that... In step 3): the intensity of the ultraviolet lamp is 80-120mW / cm², and the irradiation time is 8-12 minutes.

10. The application of the composite antifouling adsorption membrane as described in claim 1 in the field of water treatment, especially in the preparation of ultrapure water in the electronics industry, the remediation of drinking water sources, and the treatment of radioactive wastewater from nuclear power plants.