An artificial water channel permeation membrane regulated by nanobubbles and a preparation method thereof

Abstract

This invention discloses an artificial water channel permeable membrane controlled by nanobubbles and its preparation method. The artificial water channel permeable membrane comprises a water-absorbing layer, an artificial water channel layer, and a protective layer stacked sequentially. The water-absorbing layer and the protective layer are composed of superhydrophilic nanofibers. The artificial water channel layer is composed of intertwined fluorinated branched carbon nanotubes and nanobubbles uniformly distributed within their pores. The fluorinated branched carbon nanotubes are branched carbon nanotubes grafted with fluorine-containing segments, and the branched carbon nanotubes have a branched long-chain structure. This artificial water channel permeable membrane can operate under long-term conditions while maintaining high water permeability and high ion repulsion.

Description

Technical Field

[0001] This invention relates to the field of permeation membrane technology, and in particular to an artificial water channel permeation membrane controlled by nanobubbles and its preparation method. Background Technology

[0002] Water scarcity is a significant challenge facing society today, and seawater desalination is an important method for obtaining fresh water from nature to address this problem. Membrane separation technology, as an emerging technology, has enormous application potential in the field of water treatment. Membrane distillation, electrodialysis, and reverse osmosis all have important applications in seawater desalination. However, current seawater desalination membrane separation technologies all require external driving force for separation, which leads to high energy consumption and high costs.

[0003] Forward osmosis is a membrane separation process that uses the osmotic pressure difference between two solutions to drive mass transfer. In this process, water molecules on the low osmotic pressure side spontaneously transfer mass to the high osmotic pressure side, while ions in both solutions are retained, thus achieving forward osmosis. Semipermeable membranes allow water molecules to pass through while retaining ions in the water, playing a crucial role in forward osmosis.

[0004] In nature, aquaporins exhibit high water permeability and strong ion repulsion. Currently, these aquaporins have been used to synthesize artificial biomembranes, such as the aquaporin biomembrane disclosed in CN115532079A, which uses a vesicle fusion method to encapsulate the prepared aquaporin in a phospholipid bilayer membrane, and then spread it onto a nanofiltration membrane. However, because aquaporins are difficult to maintain their biological activity in high-salt environments, this aquaporin biomembrane cannot meet normal osmotic conditions; moreover, the cost of artificially purifying or manufacturing aquaporins is high, and their stability is low, limiting the application of this type of aquaporin biomembrane. Some studies have also designed and prepared artificial water channels, such as the composite biomimetic membrane with artificial water channels disclosed in CN114728241A, which uses synthesized HC8 nanocrystals embedded in a polyamide layer to prepare a composite biomimetic membrane with artificial channels. However, this membrane has a low water flux, making it difficult to meet the needs of large-scale applications. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is how to improve the stability of the permeable membrane so that it can maintain high water permeability and high ion repulsion for a long time.

[0006] To address the aforementioned technical problems, this invention provides a permeable membrane for artificial water channels regulated by nanobubbles, comprising a water-absorbing layer, an artificial water channel layer, and a protective layer stacked sequentially. The water-absorbing layer and the protective layer are composed of superhydrophilic nanofibers, and the artificial water channel layer is composed of entangled fluorinated branched carbon nanotubes and nanobubbles uniformly distributed within their pores. The fluorinated branched carbon nanotubes are branched carbon nanotubes grafted with fluorine-containing segments, and the branched carbon nanotubes have a branched long-chain structure.

[0007] This invention relates to an artificial water channel permeation membrane with a three-layer structure. The water-absorbing layer is made of superhydrophilic nanofiber membrane, which helps to reduce membrane fouling and decrease internal concentration polarization during the permeation process. The middle layer consists of fluorinated branched carbon nanotubes and nanobubbles existing between the fluorinated branched carbon nanotubes, forming artificial water channels. Due to the hydrophobicity of the fluorinated branched carbon nanotubes, nanobubbles of similar size to the pores are formed between the branched carbon nanotubes. The entangled structure of the fluorinated branched carbon nanotubes makes the existing nanobubbles more stable, thus providing long-lasting forward osmosis performance. A superhydrophilic nanofiber protective layer is then added to effectively prevent the escape of bubbles within the artificial water channel layer, which helps to improve the stability of the permeation membrane. This artificial water channel permeation membrane can operate under long-term conditions while maintaining high water permeability and high ion repulsion.

[0008] Furthermore, the branched carbon nanotubes have a diameter of 5-20 nm, a branch length of 5-15 μm, and a branching degree of 20%-80%. The diameter of the branched carbon nanotubes affects the size of the nanobubbles; within the above range, the permeation membrane performance is better. The branch length and branching degree affect the stability of the permeation membrane; exceeding the above range will lead to a decrease in stability.

[0009] Furthermore, the size of the nanobubbles is 50-300 nm. Due to the spatial confinement effect of the nanobubbles between the branched carbon nanotubes and the negative charge carried on the surface of the nanobubbles, salt ions in the water are difficult to pass through, while water molecules can be stably transported due to the sliding effect on the surface of the nanobubbles. If the size of the nanobubbles is too large, the bubbles will aggregate and the performance of the permeation membrane will decrease; if the size is too small, the ability to retain salt ions will be reduced.

[0010] Furthermore, the thickness of the artificial water channel layer is 50-200 nm, and the contact angle is 120°-150°. Limiting the thickness and contact angle range of the artificial water channel layer can balance high water flux and salt ion retention capacity. When the artificial water channel is too thick, the contact angle will increase, the water permeation resistance will increase, and the water flux will decrease. When the thickness of the artificial water channel is less than this range, the water contact angle will decrease. Although the water permeation resistance will decrease, the retention capacity of salt ions in the water will decrease.

[0011] Furthermore, the protective layer has a thickness of 10-50 μm, a contact angle of 0-10°, and a wetting time of 1-5 s; the water-absorbing layer has a thickness of 40-100 μm, an average pore diameter of 0.20-1.00 μm, a contact angle of 0-10°, and a wetting time of 1-5 s. The parameters of the protective layer and the water-absorbing layer are limited. If these parameters exceed the range, water permeation resistance will increase, and water flux will decrease; if they are below the range, nanobubbles in the artificial water channels will become unstable, and the permeation membrane will fail.

[0012] Furthermore, the superhydrophilic nanofibers in the water-absorbing layer and the protective layer have a diameter of 30-150 nm, and are made of one or more of cellulose acetate, polyethersulfone, and polyacrylonitrile. The nanofiber diameter affects the pore diameter of the water-absorbing layer and the protective layer, and within a defined range, the water flux and stability of the water-absorbing layer and the protective layer can be guaranteed.

[0013] The present invention also provides a method for preparing the above-mentioned artificial water channel permeable membrane regulated by nanobubbles, comprising the following steps:

[0014] S1. The first polymer is mixed with the first dispersion solvent to form a first electrospinning solution, and electrospinning is performed using the first electrospinning solution to prepare a water-absorbing layer.

[0015] S2, a dispersion of fluorinated branched carbon nanotubes, is deposited on the surface of the water-absorbing layer by vacuum filtration or electrostatic spraying to prepare an artificial water channel layer;

[0016] S3. Mix the second polymer with the second dispersion solvent to form a second electrospinning solution, and use the second electrospinning solution to perform electrospinning to lay a superhydrophilic protective layer on the artificial water channel layer.

[0017] S4. High-temperature hot pressing treatment is carried out to obtain an artificial water channel permeable membrane.

[0018] Further, in step S1, the first polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the first dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether; in step S2, the second polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the second dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether.

[0019] Furthermore, in step S2, the concentration of fluorinated branched carbon nanotubes in the dispersion is 0.1-1.0 mg / mL.

[0020] Furthermore, in step S2, the distribution density of fluorinated branched carbon nanotubes on the water-absorbing layer is 50-400 mg / m³. 2 The distribution density of fluorinated branched carbon nanotubes determines the thickness, contact angle, and other performance parameters of the artificial water channel layer. By limiting the concentration and distribution density of the dispersion, the artificial water channel layer can be made to have high water permeability and high ion repulsion performance.

[0021] The method for preparing the artificial water channel permeable membrane of this invention is simple and convenient, and easy to scale up. The prepared artificial water channel permeable membrane can operate under long-term conditions and maintain high water permeability and high ion repulsion, and has broad application prospects in power generation, seawater desalination, wastewater treatment and other fields. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the artificial water channel permeable membrane and the artificial water channel layer in a specific embodiment of the present invention.

[0023] Figure 2 These are transmission electron microscope images of branched carbon nanotubes in a specific embodiment of the present invention.

[0024] Figure 3 This is a scanning electron microscope image of the distribution of fluorinated branched carbon nanotubes in the water-absorbing layer in Example 1 of the present invention.

[0025] Figure 4 This is a photograph of the water contact angle of the fluorinated branched carbon nanotubes in Example 1 of this invention.

[0026] Figure 5 This is a performance test diagram of the artificial water channel permeable membrane prepared in Example 1 of the present invention. Detailed Implementation

[0027] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0028] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This application specification and embodiments are merely exemplary.

[0030] Embodiments of the present invention provide an artificial water channel permeable membrane controlled by nanobubbles and a method for its preparation. Combined with... Figure 1 As shown, the artificial water channel permeable membrane has a three-layer structure, including a water-absorbing layer, an artificial water channel layer, and a protective layer stacked sequentially. The water-absorbing layer and the protective layer are composed of superhydrophilic nanofibers, while the artificial water channel layer consists of entangled fluorinated branched carbon nanotubes and uniformly distributed nanobubbles within their pores. The fluorinated branched carbon nanotubes are branched carbon nanotubes grafted with fluorine-containing segments, and these branched carbon nanotubes have a branched long-chain structure. During use, due to the hydrophobicity of the fluorinated branched carbon nanotubes, nanobubbles of similar size to the pores are formed between the branched carbon nanotubes. Due to the spatial confinement effect of the nanobubbles between the branched carbon nanotubes and the negative charge carried on the surface of the nanobubbles, salt ions in the water are difficult to pass through, while water molecules can be stably transported due to the sliding effect on the surface of the nanobubbles. This achieves both high water permeability and high ion repulsion in the permeable membrane.

[0031] In a specific embodiment of the present invention, the water-absorbing layer is a superhydrophilic nanofiber membrane, the material of which can be selected from cellulose acetate, polyethersulfone, polyacrylonitrile, etc., with a nanofiber diameter of 30-150 nm; the thickness of the water-absorbing layer is 40-100 μm, the average pore diameter is 0.20-1.00 μm, the instantaneous water droplet contact angle is 0-10°, and the wetting time is 1-5 s. The water-absorbing layer has excellent water permeability, which helps to reduce membrane fouling and reduce internal concentration polarization during the permeation process.

[0032] In a specific embodiment of the present invention, the protective layer is a superhydrophilic nanofiber membrane, the material of which can be selected from polyacrylonitrile, polyethersulfone, cellulose acetate, etc., with a nanofiber diameter of 30-150 nm; the thickness of the protective layer is 10-50 μm, the instantaneous water droplet contact angle is 0-10°, and the wetting time is 1-5 s. The protective layer has excellent water permeability but can prevent nanobubbles from passing through, thereby preventing the escape of bubbles within the artificial water channel layer and helping to improve the stability of the permeable membrane.

[0033] In a specific embodiment of the present invention, the thickness of the artificial water channel layer is 50-200 nm, and the contact angle is 120°-150°. The artificial water channel selective layer is composed of intertwined fluorinated branched carbon nanotubes and uniformly distributed nanobubbles within their pores, with the nanobubbles having a size of 50-300 nm; the fluorinated branched carbon nanotubes are branched carbon nanotubes grafted with fluorine-containing segments, and the morphology of the branched carbon nanotubes is as follows. Figure 2 As shown, it is a carbon nanotube with a branched long-chain structure. In a specific embodiment, the diameter of the branched carbon nanotube is 5-20 nm, the branch length is 5-15 μm, and the degree of branching is 20%-80%.

[0034] The preparation method of the above-mentioned artificial water channel permeable membrane includes the following steps:

[0035] S1. The first polymer is mixed with the first dispersing solvent to form a first electrospinning solution, and electrospinning is performed using the first electrospinning solution to prepare a water-absorbing layer.

[0036] In a specific embodiment, the first polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the first dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether. The first polymer powder and the first dispersing solvent are stirred at 50-90°C for 6-10 hours to form a first electrospinning solution with a polymer mass fraction of 6%-12%.

[0037] In a specific implementation, the electrospinning process parameters for the water-absorbing layer are as follows: nozzle diameter is 0.8-1.1 mm, liquid injection speed is 0.9-1.2 mL / h, electrospinning voltage is 10-22 KV, receiving distance is 14-18 cm, needle movement distance is 100-300 cm, receiving roller speed is 200-300 rpm, electrospinning temperature is 20-40℃, spinning ambient humidity is 20-60%, and spinning time is 5-10 h.

[0038] S2. Fluorinated branched carbon nanotubes are mixed with a second dispersing solvent to form a dispersion. The dispersion is deposited on the surface of the water-absorbing layer by vacuum filtration or electrostatic spraying to prepare an artificial water channel layer.

[0039] In a specific embodiment, the concentration of the fluorinated branched carbon nanotube dispersion is 0.1-1.0 mg / mL, and the dispersion solvent is one of ethanol, methanol, and ethylene glycol.

[0040] In one specific embodiment, the fluorinated branched carbon nanotubes are deposited via vacuum filtration with a filtration pressure difference of 0-1 bar, and the distribution density of the fluorinated branched carbon nanotubes on the water-absorbing layer is 50-400 mg / m³. 2 .

[0041] In another specific embodiment, the fluorinated branched carbon nanotubes are deposited by electrostatic spraying, and the spraying process parameters are as follows: the nozzle diameter is 0.8-1.1 mm, the dispersion injection speed is 0.9-1.2 mL / h, the spraying voltage is 10-22 KV, the receiving distance is 14-18 cm, the needle movement distance is 100-300 cm, the receiving roller speed is 200-300 rpm, the spraying temperature is 20-40℃, the spraying ambient humidity is 20-60%, and the spraying time is 5-10 h.

[0042] S3. The second polymer is mixed with the second dispersion solvent to form a second electrospinning solution. Electrospinning is performed using the second electrospinning solution to lay a superhydrophilic protective layer on the artificial water channel layer.

[0043] In a specific embodiment, the second polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the second dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether. The second polymer powder and the second dispersing solvent are stirred at 50-90°C for 6-10 hours to form a second electrospinning solution with a polymer mass fraction of 6%-12%.

[0044] In a specific implementation, the electrospinning process parameters for the protective layer are as follows: nozzle diameter is 0.8-1.1 mm, liquid injection speed is 0.9-1.2 mL / h, electrospinning voltage is 13-22 KV, receiving distance is 14-18 cm, needle movement distance is 100-220 cm, receiving roller speed is 250-350 rpm, electrospinning temperature is 20-40℃, spinning ambient humidity is 20-60%, and spinning time is 1-4 h.

[0045] S4. High-temperature hot pressing treatment is carried out to obtain an artificial water channel permeable membrane.

[0046] In a specific implementation, the temperature of the high-temperature hot pressing is 60-100℃, and the hot pressing time is 2-6 hours.

[0047] The above preparation method is simple and convenient, and easy to scale up. The prepared artificial water channel permeable membrane can operate under long-term conditions and maintain high water permeability and high ion repulsion, and has broad application prospects in power generation, seawater desalination, wastewater treatment and other fields.

[0048] The present invention will be further described in detail below with reference to specific embodiments.

[0049] Example 1

[0050] (1) Polyacrylonitrile powder was dissolved in a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide (mass ratio 1:1) and stirred at 80°C for 10 h to prepare an electrospinning solution with a polymer mass fraction of 6%.

[0051] (2) Take 8 mL of the electrospinning solution from step (1) and put it into a syringe. Install the syringe on an electrospinning machine to spin the solution and prepare the first water-absorbing layer. The electrospinning parameters are as follows: nozzle diameter is 0.8 mm, liquid injection speed is 1.0 mL / h, electrospinning voltage is 16.5 KV, receiving distance is 16 cm, receiving roller speed is 300 rpm, needle movement distance is 280 cm, electrospinning temperature is 40℃, spinning environment humidity is 20%, and spinning time is 8 h.

[0052] (3) An artificial water channel layer was prepared by depositing 1.50 mL of a 0.5 mg / mL fluorinated branched carbon nanotube ethanol dispersion onto a hydrophilic and porous electrospun substrate membrane using vacuum filtration at a pressure difference of 0 bar. The distribution density of the fluorinated branched carbon nanotubes was 400 mg / m³. 2 The distribution of fluorinated branched carbon nanotubes in the water-absorbing layer is as follows: Figure 3 As shown, fluorinated branched carbon nanotubes are entangled with each other; the water contact angle of the fluorinated branched carbon nanotubes was measured, and the results are as follows. Figure 4 As shown, the water contact angle is 150°, exhibiting strong hydrophobicity. During the use of the permeation membrane, nanobubbles similar in size to the pores will form between the branched carbon nanotubes.

[0053] (4) Take 10 mL of the electrospinning solution from step (1) and put it into a syringe. Then, lay a protective layer on the artificial water channel layer by electrospinning. The electrospinning parameters are as follows: nozzle diameter is 0.8 mm, liquid injection speed is 1.0 mL / h, electrospinning voltage is 16.5 KV, receiving distance is 16 cm, needle movement distance is 200 cm, receiving roller speed is 300 rpm, electrospinning temperature is 40℃, spinning environment humidity is 20%, and spinning time is 3 h.

[0054] (5) After spinning, the membrane is placed in an 80℃ oven for 4 hours to obtain a permeable membrane with artificial water channels.

[0055] The permeable membrane of the prepared artificial water channel was subjected to permeability testing. 1 mol / L NaCl was used as the draw solution and deionized water as the feed solution. The results are as follows: Figure 5 As shown, the forward water flux is 27 Lm. -2 h -1 The reverse salt flux was as low as 0.085 gm. -2 h -1After 4 hours of operation, the water flux decreased by only 6%, indicating that the permeation membrane has extremely high water-salt selectivity and stability.

[0056] Example 2

[0057] (1) Dissolve polyethersulfone in N,N-dimethylformamide and stir at 80°C for 10 h to prepare an electrospinning solution with a polymer mass fraction of 8%.

[0058] (2) Take 8 mL of the electrospinning solution from step (1) and put it into a syringe. Install the syringe on an electrospinning machine to spin and prepare a water-absorbing layer. The electrospinning parameters are: nozzle diameter 0.8 mm, liquid injection speed 1.0 mL / h, electrospinning voltage 16.5 KV, receiving distance 16 cm, needle movement distance 280 cm, receiving roller speed 300 rpm, electrospinning temperature 40℃, spinning environment humidity 20%, and spinning time 8 h.

[0059] (3) A 0.25 mL methanol dispersion of fluorinated branched carbon nanotubes with a concentration of 0.5 mg / mL was deposited onto a hydrophilic and porous electrospun substrate membrane by vacuum filtration at a pressure difference of 1.0 bar to prepare an artificial water channel layer, wherein the distribution density of the hydrophobic branched carbon nanotube layer was 60 mg / m³. 2 .

[0060] (4) Take 9 mL of the electrospinning solution from step (1) and put it into a syringe. Then, use electrospinning to lay a protective layer on the artificial water channel layer. The electrospinning parameters are as follows: nozzle diameter is 0.9 mm, liquid injection speed is 1.1 mL / h, electrospinning voltage is 15.5 KV, receiving distance is 15 cm, needle movement distance is 180 cm, receiving roller speed is 260 rpm, electrospinning temperature is 30℃, spinning environment humidity is 15%, and spinning time is 3 h.

[0061] (5) After spinning, the membrane is placed in an 80℃ oven for hot pressing for 3 hours to obtain a permeable membrane with artificial water channels.

[0062] The prepared permeable membrane was used for permeation testing. 1 mol / L NaCl was used as the draw solution and deionized water as the feed solution. The result showed a forward water flux of 29 Lm. -2 h -1 The reverse salt flux is as low as 0.10 gm. -2 h -1 After 8 hours of operation, the water flux decreased by only 5%, demonstrating that the permeation membrane exhibits extremely high water-salt selectivity and stability.

[0063] Example 3

[0064] (1) Dissolve cellulose acetate in a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide (mass ratio 2:1) and stir at 60°C for 9 h to prepare an electrospinning solution with a polymer mass fraction of 10%.

[0065] (2) Take 8.8 mL of the electrospinning solution from step (1) and put it into a syringe. Install the syringe on an electrospinning machine to spin and prepare a water-absorbing layer. The electrospinning parameters are: nozzle diameter 0.9 mm, liquid injection speed 1.1 mL / h, electrospinning voltage 13.5 KV, receiving distance 16 cm, needle movement distance 280 cm, receiving roller speed 300 rpm, electrospinning temperature 25℃, spinning environment humidity 20%, and spinning time 8 h.

[0066] (3) A 0.50 mL ethanol dispersion of fluorinated branched carbon nanotubes with a concentration of 0.5 mg / mL was deposited onto a hydrophilic and porous electrospun substrate membrane by vacuum filtration at a pressure difference of 0.5 bar to prepare an artificial water channel layer, wherein the distribution density of the hydrophobic branched carbon nanotube layer was 200 mg / m³. 2 .

[0067] (4) Take 8.8 mL of the electrospinning solution from step (1) and put it into a syringe. Then, use electrospinning to lay a protective layer on the artificial water channel layer. The electrospinning parameters are as follows: nozzle diameter is 0.9 mm, liquid injection speed is 1.1 mL / h, electrospinning voltage is 15.5 KV, receiving distance is 15 cm, needle movement distance is 200 cm, receiving roller speed is 260 rpm, electrospinning temperature is 30℃, spinning environment humidity is 15%, and spinning time is 3 h.

[0068] (5) After spinning, the membrane is placed in a 100℃ oven for 4 hours to obtain a permeable membrane with artificial water channels.

[0069] The prepared permeable membrane was used for permeation testing. 1 mol / L NaCl was used as the draw solution and deionized water as the feed solution. The result showed a forward water flux of 26 Lm. -2 h -1 The reverse salt flux is as low as 0.13 gm. -2 h -1 After 6 hours of operation, the water flux decreased by only 8%, demonstrating that the permeation membrane exhibits extremely high water-salt selectivity and stability.

[0070] Example 4

[0071] (1) Polyacrylonitrile powder was dissolved in a mixed solution of N,N-dimethylformamide and N,N-dimethylacetamide (mass ratio 1:1) and stirred at 80°C for 7 h to prepare an electrospinning solution with a polymer mass fraction of 9%.

[0072] (2) Take 8 mL of the electrospinning solution from step (1) and put it into a syringe. Install the syringe on an electrospinning machine to spin and prepare a water-absorbing layer. The electrospinning parameters are: nozzle diameter 0.8 mm, liquid injection speed 1.0 mL / h, electrospinning voltage 16.5 KV, receiving distance 16 cm, needle movement distance 280 cm, receiving roller speed 300 rpm, electrospinning temperature 40℃, spinning environment humidity 20%, and spinning time 8 h.

[0073] (3) 7.50 mL of an ethanol dispersion of fluorinated branched carbon nanotubes with a concentration of 8 mg / mL was placed on an electrostatic spraying device. The spraying parameters were: nozzle diameter 0.9 mm, liquid injection speed 1.2 mL / h, electrostatic spraying voltage 12 KV, receiving distance 16 cm, needle movement distance 180 cm, receiving roller speed 300 rpm, electrostatic spraying temperature 30℃, spraying ambient humidity 30%, and spraying time 6 h. An artificial water channel layer was prepared, in which the distribution density of fluorinated branched carbon nanotubes was 235 mg / m³. 2 .

[0074] (4) Take 8 mL of the electrospinning solution from step (1) and put it into a syringe. Then, lay a protective layer on the artificial water channel layer by electrospinning. The electrospinning parameters are as follows: nozzle diameter is 0.9 mm, liquid injection speed is 1.1 mL / h, electrospinning voltage is 15.5 KV, receiving distance is 15 cm, needle movement distance is 190 cm, receiving roller speed is 260 rpm, electrospinning temperature is 30℃, spinning environment humidity is 25%, and spinning time is 3 h.

[0075] (5) After spinning, the membrane is placed in an 80℃ oven for 4 hours to obtain a permeable membrane with artificial water channels.

[0076] The prepared permeable membrane was used for permeation testing. 1 mol / L NaCl was used as the draw solution and deionized water as the feed solution. The result showed a forward water flux of 26.5 Lm. -2 h -1 The reverse salt flux is as low as 0.10 gm. -2 h -1 After 5 hours of operation, the water flux decreased by only 5.5%, demonstrating that the permeation membrane exhibits extremely high water-salt selectivity and stability.

[0077] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of this disclosure, and all such changes and modifications will fall within the scope of protection of this invention.

Claims

1. An artificial aquaporin permeation membrane regulated by nanobubbles, characterized in that, The device comprises a water-absorbing layer, an artificial water channel layer, and a protective layer stacked sequentially. The water-absorbing layer and the protective layer are made of superhydrophilic nanofibers through electrospinning. The artificial water channel layer consists of entangled fluorinated branched carbon nanotubes and nanobubbles uniformly distributed within their pores. The fluorinated branched carbon nanotubes are branched carbon nanotubes grafted with fluorine-containing segments. The branched carbon nanotubes have a branched long-chain structure with a diameter of 5-20 nm, a branch length of 5-15 μm, and a branching degree of 20%-80%.

2. The artificial aquaporin channel permeation membrane regulated by nanobubbles according to claim 1, characterized in that, The size of the nanobubbles is 50-300 nm.

3. The artificial aquaporin channel permeation membrane regulated by nanobubbles according to claim 1, characterized in that, The artificial water channel layer has a thickness of 50-200 nm and a contact angle of 120°-150°.

4. The artificial aquaporin channel permeation membrane regulated by nanobubbles according to any one of claims 1-3, characterized in that, The protective layer has a thickness of 10-50 μm, a contact angle of 0-10°, and a wetting time of 1-5 s; the water-absorbing layer has a thickness of 40-100 μm, an average pore diameter of 0.20-1.00 μm, a contact angle of 0-10°, and a wetting time of 1-5 s.

5. The artificial aquaporin channel permeation membrane regulated by nanobubbles according to any one of claims 1-3, characterized in that, The superhydrophilic nanofibers of the water-absorbing layer and the protective layer have a diameter of 30-150 nm and are made of one or more of cellulose acetate, polyethersulfone, and polyacrylonitrile.

6. A method for producing the artificial aquaporin permeation membrane regulated by nanobubbles according to any one of claims 1 to 5, characterized by, Includes the following steps: S1. The first polymer is mixed with the first dispersion solvent to form a first electrospinning solution, and electrospinning is performed using the first electrospinning solution to prepare a water-absorbing layer. S2, a dispersion of fluorinated branched carbon nanotubes, is deposited on the surface of the water-absorbing layer by vacuum filtration or electrostatic spraying to prepare an artificial water channel layer; S3. Mix the second polymer with the second dispersion solvent to form a second electrospinning solution, and use the second electrospinning solution to perform electrospinning to lay a superhydrophilic protective layer on the artificial water channel layer. S4. High-temperature hot pressing treatment is carried out to obtain an artificial water channel permeable membrane.

7. The method of claim 6, wherein the method is characterized by, In step S1, the first polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the first dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether; in step S3, the second polymer is selected from one or more combinations of cellulose acetate, polyethersulfone, and polyacrylonitrile, and the second dispersing solvent is selected from one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, ethanol, and petroleum ether.

8. The method of claim 7, wherein the method is characterized by, In step S2, the concentration of fluorinated branched carbon nanotubes in the dispersion is 0.1-1.0 mg / mL.

9. The method of claim 7, wherein the method is characterized by, The distribution density of the fluorinated branched carbon nanotubes on the water-sucking layer in the step S2 is 50-400 mg / m 2 .

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