Forward osmosis membrane material capable of effectively improving internal concentration polarization and application of forward osmosis membrane material

Abstract

The invention discloses a forward osmosis membrane material capable of effectively improving internal concentration polarization and application thereof.The forward osmosis membrane material comprises a membrane base material, a surface modification layer and an internal concentration polarization improvement layer.The forward osmosis membrane material has the advantages that the internal concentration polarization improvement layer is introduced, the forward osmosis membrane material is prepared from nanowires, nanotubes and nanosheets, and the internal concentration polarization improvement layer is prepared from the nanowires, the nanotubes and the nanosheets; the concentration polarization phenomenon is effectively reduced, and the permeation flux and salt rejection rate of the membrane are improved, so that the membrane material can maintain relatively high performance stability in a long-time operation process, and the membrane material is particularly suitable for a scene in which industrial wastewater treatment needs long-time continuous operation; by arranging the multi-layer structure of the membrane material, not only are the permeability and selectivity of the membrane improved, but also the mechanical strength, chemical stability and anti-pollution performance of the membrane material are enhanced, and especially by introducing the reinforcing layer, one of the fiber fabric, the grid and the inorganic filler is combined with the binder, so that the anti-pollution performance of the membrane material is improved. The durability and the service life of the membrane material are obviously improved.

Description

Technical Field

[0001] The present invention relates to the technical field of forward osmosis membrane materials, and particularly to a forward osmosis membrane material capable of effectively improving internal concentration polarization and its application. Background Technique

[0002] In the field of membrane separation technology, forward osmosis (FO), as an emerging water treatment technology, has attracted much attention due to its low energy consumption, high water recovery rate, and high-efficiency interception ability for pollutants. However, forward osmosis membrane materials often face the problem of internal concentration polarization (ICP) in practical applications, which greatly limits their permeation flux and separation efficiency. Internal concentration polarization refers to the increase in osmotic pressure caused by the solute concentration gradient at the interface between the membrane and the support layer, resulting in the obstruction of the natural osmosis process of water molecules from the high-concentration solution to the low-concentration solution. Traditional forward osmosis membrane materials often consist of only a single membrane substrate and a selective layer. Such a structure is difficult to effectively cope with the challenges brought by internal concentration polarization. Although some forward osmosis membrane materials with multi-layer structures have been proposed, traditional inorganic filler or fiber fabric reinforcement methods often have problems such as poor binding with the membrane substrate and easy shedding, which affect the long-term stability and service life of the membrane. Forward osmosis membranes need to withstand a certain pressure difference and fluid shear force, so the membrane materials are required to have good mechanical properties. When treating complex environments such as industrial wastewater, the membrane materials need to have good chemical stability to resist the erosion of chemical substances such as acids, alkalis, and oxidants. However, existing forward osmosis membrane materials are prone to degradation or performance decline in these environments. Summary of the Invention

[0003] The purpose of the present invention is to provide a forward osmosis membrane material capable of effectively improving internal concentration polarization and its application, so as to solve the problems in the above background technique that traditional inorganic filler or fiber fabric reinforcement methods often have problems such as poor binding with the membrane substrate and easy shedding, which affect the long-term stability and service life of the membrane. Forward osmosis membranes need to withstand a certain pressure difference and fluid shear force, so the membrane materials are required to have good mechanical properties. When treating complex environments such as industrial wastewater, the membrane materials need to have good chemical stability to resist the erosion of chemical substances such as acids, alkalis, and oxidants. However, existing forward osmosis membrane materials are prone to degradation or performance decline in these environments.

[0004] To achieve the above object, the present invention provides the following technical solution: a forward osmosis membrane material that effectively improves internal concentration polarization, including a forward osmosis membrane material. The forward osmosis membrane material consists of a membrane substrate, a surface modification layer, an internal concentration polarization improvement layer, a functional layer, a transition layer, a selective layer, a protective layer, a reinforcing layer, a catalytic layer, and an ion exchange layer. A protective layer is provided on the outer side of the membrane substrate, a catalytic layer is provided on the outer side of the protective layer, an ion exchange layer is provided on the outer side of the catalytic layer, a reinforcing layer is provided on the outer side of the ion exchange layer, a porous support layer is provided on the outer side of the reinforcing layer, a transition layer is provided on the outer side of the porous support layer, an internal concentration polarization improvement layer is provided on the outer side of the transition layer, a functional layer is provided on the outer side of the internal concentration polarization improvement layer, a selective layer is provided on the outer side of the functional layer, and a surface modification layer is provided on the outer side of the selective layer.

[0005] Preferably, the internal concentration polarization improvement layer is made of MOFs, COFs, and nanowires, where the mass ratio of MOFs, COFs, and nanowires is 3 - 1:2 - 1:4 - 1. The MOFs, COFs, and nanowires are compounded by an electrostatic self-assembly method. The functional layer is made of a blend material of polyamide and cellulose acetate. The transition layer is made of a blend material of inorganic nanoparticles and a polymer.

[0006] The electrostatic self-assembly method specifically includes the following steps:

[0007] F1. Disperse MOFs and COFs particles in an aqueous solution containing a specific surfactant, and perform ultrasonic treatment to make them uniformly dispersed to form a stable dispersion.

[0008] F2. Disperse the nanowires in another aqueous solution containing a surfactant with an opposite charge, and also perform ultrasonic treatment to form a nanowire dispersion.

[0009] F3. Mix the two dispersions and carry out an electrostatic self-assembly reaction at a specific temperature and stirring speed for 1 - 3 h.

[0010] F4. After the reaction, obtain the MOFs, COFs, and nanowire composite through steps such as centrifugation, washing, and drying.

[0011] Preferably, the selective layer is made of a high molecular polymer or an inorganic material, and the protective layer is made of one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and perfluoroalkoxy resin.

[0012] Preferably, the reinforcing layer is one of a fiber fabric, a grid, and an inorganic filler. The catalytic layer is a metal oxide, and the catalytic layer is loaded with a catalytically active nanozyme that can catalytically degrade the intercepted organic matter during the forward osmosis process. The ion exchange layer is made of sulfonic acid groups, carboxyl groups, and quaternary ammonium salts.

[0013] The forward osmosis membrane material is prepared by a method combining 3D printing and in-situ growth. First, the preliminary structure of the membrane material is precisely constructed by 3D printing technology, and then in-situ growth is carried out under specific conditions to make the materials of each layer closely combined and the structure uniform. The 3D printing technology uses photocuring 3D printing with a printing accuracy of 10 - 50 microns; the conditions for in-situ growth are in a specific solution at 60 - 90 °C with a reaction time of 12 - 24 h.

[0014] Preferably, the preparation method of the membrane substrate specifically includes the following steps:

[0015] A1. Weigh polylactic acid and polyhydroxyalkanoate, and prepare the weighed polylactic acid and polyhydroxyalkanoate by melt blending method;

[0016] A2. Dry the polylactic acid and polyhydroxyalkanoate to reduce the moisture content;

[0017] A3. After drying, put it into a high-speed mixer to mix evenly, and then add it to a twin-screw extruder to carry out modified granulation at a temperature of 120 - 180 °C;

[0018] A4. Add the modified resin into a blown film machine to carry out blown film, and then the membrane substrate can be obtained.

[0019] Preferably, the preparation method of the transition layer specifically includes the following steps:

[0020] B1. Measure inorganic nanoparticles and disperse them evenly in a pre-prepared polymer solution to ensure that there is no agglomeration between particles;

[0021] B2. Adopt a precision knife coating process, and evenly and continuously scrape the mixed solution on the surface of the substrate with a knife, and a transition layer is formed after the solvent volatilizes.

[0022] Preferably, the preparation method of the selective layer specifically includes the following steps:

[0023] C1. The polymer selective layer is prepared by solvent evaporation method to form a selective layer with a microporous structure to block macromolecules or ions;

[0024] C2. The inorganic material selective layer is prepared by chemical vapor deposition method to form a selective layer with a microporous structure to block macromolecules or ions.

[0025] Preferably, the preparation method of the reinforcing layer specifically includes the following steps:

[0026] D1. Fibers are formed into fiber fabrics by weaving technology;

[0027] D2. For inorganic fillers, they need to be first mixed evenly with the binder.

[0028] D3. After being mixed evenly, through the pressing and forming process, the mixture is tightly adhered to the surface of the substrate under high pressure. After curing treatment, the inorganic filler combines with the fiber fabric to form a strong reinforcing layer.

[0029] Preferably, the preparation method of the ion exchange layer specifically includes the following steps:

[0030] E1. Sulfonic acid groups and carboxyl functional groups are introduced onto the surface of the membrane material by means of chemical reactions.

[0031] E2. The functional groups carry exchangeable ions and can displace other ions in the solution, thereby endowing the membrane material with the ability of ion exchange to obtain the ion exchange layer.

[0032] The present invention also provides the application of the forward osmosis membrane material that can effectively improve internal concentration polarization in industrial wastewater treatment.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows: By introducing an internal concentration polarization improvement layer made of nanowires, nanotubes, and nanoplates, the forward osmosis membrane material effectively reduces the concentration polarization phenomenon, improves the membrane's permeation flux and salt rejection rate, enabling the membrane material to maintain high performance stability during long-term operation, and is particularly suitable for scenarios in industrial wastewater treatment that require long-term continuous operation; By setting the multi-layer structure of the membrane material, not only the permeation performance and selectivity of the membrane are improved, but also the mechanical strength, chemical stability, and anti-fouling performance of the membrane material are enhanced. In particular, the introduction of the reinforcing layer, through the combination of one of the fiber fabric, grid, and inorganic filler with the binder, significantly improves the durability and service life of the membrane material. Specific Embodiments

[0034] The present invention provides a technical solution: A forward osmosis membrane material that can effectively improve internal concentration polarization, including a forward osmosis membrane material. The forward osmosis membrane material consists of a membrane substrate, a surface modification layer, an internal concentration polarization improvement layer, a functional layer, a transition layer, a selective layer, a protective layer, a reinforcing layer, a catalytic layer, and an ion exchange layer. A protective layer is arranged on the outer side of the membrane substrate, a catalytic layer is arranged on the outer side of the protective layer, an ion exchange layer is arranged on the outer side of the catalytic layer, a reinforcing layer is arranged on the outer side of the ion exchange layer, a porous support layer is arranged on the outer side of the reinforcing layer, a transition layer is arranged on the outer side of the porous support layer, an internal concentration polarization improvement layer is arranged on the outer side of the transition layer, a functional layer is arranged on the outer side of the internal concentration polarization improvement layer, a selective layer is arranged on the outer side of the functional layer, and a surface modification layer is arranged on the outer side of the selective layer. Through the functions and positions of each layer, the internal concentration polarization phenomenon is effectively improved. This multi-layer structure not only improves the permeation performance of the membrane, but also enhances its selectivity and durability, providing a high-performance membrane material for the field of industrial wastewater treatment.

[0035] Among them, the membrane substrate is made of a blend material of polylactic acid and polyhydroxyalkanoate. The surface modification layer is a small molecule compound containing hydrophilic groups. The internal concentration polarization improvement layer is made of MOFs, COFs, and nanowires, where the mass ratio of MOFs, COFs, and nanowires is 3 - 1:2 - 1:4 - 1. The MOFs, COFs, and nanowires are compounded by an electrostatic self-assembly method. The functional layer is made of a blend material of polyamide and cellulose acetate. The transition layer is made of a blend material of inorganic nanoparticles and polymers;

[0036] The electrostatic self-assembly method specifically includes the following steps:

[0037] F1. Disperse MOFs and COFs particles in an aqueous solution containing a specific surfactant, and perform ultrasonic treatment to make them uniformly dispersed to form a stable dispersion;

[0038] F2. Disperse the nanowires in another aqueous solution containing a surfactant with an opposite charge, and also perform ultrasonic treatment to form a nanowire dispersion;

[0039] F3. Mix the two dispersions, and carry out an electrostatic self-assembly reaction at a specific temperature and stirring speed. The reaction time is 1 - 3 h;

[0040] F4. After the reaction, obtain the MOFs, COFs, and nanowire composite through steps such as centrifugation, washing, and drying. The membrane substrate is made of a blend material of polylactic acid and polyhydroxyalkanoate, which improves the mechanical strength and biocompatibility of the membrane. At the same time, the selection of each layer of material also optimizes the overall performance of the membrane. The surface modification layer uses a small molecule compound containing hydrophilic groups, which enhances the hydrophilicity and anti-pollution ability of the membrane.

[0041] Among them, the selective layer is made of a high molecular polymer or an inorganic material. The protective layer is made of one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and perfluoroalkoxy resin. The selective layer has a microporous structure that can block macromolecules or ions, improving the separation efficiency of the membrane. The protective layer is made of polytetrafluoroethylene material, enhancing the chemical stability and corrosion resistance of the membrane and extending the service life of the membrane.

[0042] Among them, the reinforcing layer is one of a fiber fabric, a grid, and an inorganic filler. The catalytic layer is a metal oxide, and the catalytic layer is loaded with a catalytically active nanozyme. This nanozyme can catalytically degrade the intercepted organic matter during the forward osmosis process. The ion exchange layer is made of sulfonic acid groups, carboxyl groups, and quaternary ammonium salts;

[0043] The forward osmosis membrane material is prepared by a method combining 3D printing and in-situ growth. First, the preliminary structure of the membrane material is precisely constructed by 3D printing technology, and then in-situ growth is carried out under specific conditions to make the materials of each layer closely combined and the structure uniform. The 3D printing technology uses photocuring 3D printing with a printing accuracy of 10 - 50 microns. The conditions for in-situ growth are in a specific solution at 60 - 90 °C for a reaction time of 12 - 24 h. The introduction of the reinforcing layer improves the mechanical strength of the membrane, enabling it to withstand greater operating pressures. The catalytic layer is made of metal oxide and has a catalytic effect, capable of accelerating the progress of certain chemical reactions.

[0044] Among them, the preparation method of the membrane substrate specifically includes the following steps:

[0045] A1. Weigh polylactic acid and polyhydroxyalkanoate, and prepare the weighed polylactic acid and polyhydroxyalkanoate by melt blending method;

[0046] A2. Dry the polylactic acid and polyhydroxyalkanoate to reduce the moisture content;

[0047] A3. After drying, put it into a high-speed mixer to mix evenly, and then add it to a twin-screw extruder for modified granulation at a temperature of 120 - 180 °C;

[0048] A4. Add the modified resin to a blown film machine for blown film to obtain the membrane substrate;

[0049] It can ensure the consistency of the quality and performance of the membrane substrate, providing a solid foundation for the subsequent preparation of the membrane layer.

[0050] Among them, the preparation method of the transition layer specifically includes the following steps:

[0051] B1. Measure inorganic nanoparticles and disperse them evenly in a pre-prepared polymer solution to ensure that there is no agglomeration between the particles;

[0052] B2. Adopt a precision doctor blade coating process, and evenly and continuously scrape the mixed solution on the surface of the substrate with a doctor blade to form a transition layer after the solvent evaporates;

[0053] By measuring inorganic nanoparticles and dispersing them evenly in the polymer solution, and then using the precision doctor blade coating process to scrape the mixed solution on the surface of the substrate to form a transition layer, it can ensure the uniformity and denseness of the transition layer and improve the overall performance of the membrane.

[0054] Among them, the preparation method of the selective layer specifically includes the following steps:

[0055] C1. The polymer selective layer is prepared by solvent evaporation method to form a selective layer with a microporous structure to block macromolecules or ions;

[0056] C2. The inorganic material selective layer is prepared by chemical vapor deposition to form a selective layer with a microporous structure to block macromolecules or ions;

[0057] The polymer selective layer is prepared by solvent evaporation and the inorganic material selective layer is prepared by chemical vapor deposition. Both of these preparation methods can form a selective layer with a microporous structure, effectively block macromolecules or ions, and improve the separation efficiency of the membrane.

[0058] Among them, the preparation method of the reinforcing layer specifically includes the following steps:

[0059] D1. Fibers are formed into a fiber fabric by weaving technology;

[0060] D2. For inorganic fillers, they need to be first mixed evenly with a binder;

[0061] D3. After being mixed evenly, through a pressing and forming process, the mixture is tightly adhered to the surface of the substrate under high pressure. After curing treatment, the inorganic filler and the fiber fabric are combined to form a firm reinforcing layer;

[0062] Forming a fiber fabric by weaving fibers or pressing and forming after mixing inorganic fillers and a binder can ensure the tight combination and firmness of the reinforcing layer with the substrate, and improve the mechanical strength and durability of the membrane.

[0063] Among them, the preparation method of the ion exchange layer specifically includes the following steps:

[0064] E1. Sulfonic acid groups and carboxyl functional groups are introduced onto the surface of the membrane material by chemical reaction;

[0065] E2. The functional groups carry exchangeable ions and can displace other ions in the solution, thereby endowing the membrane material with ion exchange ability to obtain an ion exchange layer;

[0066] Introducing sulfonic acid groups and carboxyl functional groups onto the surface of the membrane material by chemical reaction endows the membrane material with ion exchange ability. The process is simple, easy to operate, and can ensure the uniformity and effectiveness of the ion exchange layer.

[0067] The present invention also provides the application of the forward osmosis membrane material that can effectively improve internal concentration polarization in industrial wastewater treatment.

[0068] Example 1:

[0069] Weigh an appropriate amount of polylactic acid and polyhydroxyalkanoate, and prepare a blend material by melt blending method. Dry the material after melt blending to reduce its moisture content. Subsequently, put the dried material into a high-speed mixer and mix it evenly, then add it to a twin-screw extruder and carry out modified granulation at 160 °C. Finally, add the modified resin to a blown film machine and obtain a film substrate through the blown film process. Preparation of the transition layer: Measure a certain amount of silica nanoparticles and disperse them evenly in a pre-prepared polyvinyl alcohol solution to ensure no agglomeration. Adopt the precision knife coating process to evenly and continuously coat the mixed solution on the surface of the film substrate. After the solvent evaporates, a transition layer is formed. Preparation of the selective layer: Select the polymer polyvinylidene fluoride (PVDF) as the selective layer material. By the solvent evaporation method, evenly coat the PVDF solution on the surface of the transition layer, and then evaporate the solvent to form a selective layer with a microporous structure. Preparation of other layers: Sequentially coat a fiber fabric reinforcement layer, an inorganic filler (calcium carbonate) reinforcement layer, an internal concentration polarization improvement layer, a functional layer (blended from polyamide and cellulose acetate), a protective layer (polytetrafluoroethylene), a catalytic layer (titanium oxide), and an ion exchange layer (introduce sulfonic acid group functional groups through chemical reaction) on the outside of the selective layer. Finally, coat a small molecule compound containing hydrophilic groups on the outside of the ion exchange layer for surface modification;

[0070] Example 2. Preparation of the film substrate: Select polylactic acid and polyhydroxyalkanoate as raw materials, and prepare a film substrate through a series of process steps such as melt blending, drying, mixing, modified granulation, and blown film. The specific process conditions are the same as those in Example 1. Preparation of the transition layer: Measure an appropriate amount of alumina nanoparticles and disperse them evenly in the polyvinyl alcohol solution. Adopt the precision knife coating process to evenly coat the mixed solution on the surface of the film substrate to form a transition layer. Preparation of the selective layer: Use the inorganic material silane as a precursor and deposit an inorganic selective layer with a microporous structure on the surface of the transition layer by chemical vapor deposition method. Preparation of other layers: Sequentially coat a fiber fabric reinforcement layer (such as glass fiber fabric), an inorganic filler (montmorillonite) reinforcement layer, an internal concentration polarization improvement layer, a functional layer (blended from polyamide and another polymer material), a protective layer (ethylene-tetrafluoroethylene copolymer), a catalytic layer (cobalt oxide), and an ion exchange layer (introduce carboxyl group functional groups through chemical reaction) on the outside of the inorganic selective layer. Finally, carry out surface modification to improve the hydrophilicity and anti-pollution ability of the membrane;

[0071] Example 3: Preparation of membrane substrate: Weigh polylactic acid and polyhydroxyalkanoate and mix them in a ratio of 7:3. Through process steps such as melt blending, drying, mixing, modified granulation, and blown film, a membrane substrate is prepared. Preparation of the transition layer: Measure an appropriate amount of barium titanate nanoparticles and uniformly disperse them in a polyvinyl alcohol solution. Using a precision doctor blade coating process, the mixed solution is uniformly coated on the surface of the membrane substrate to form a transition layer. Preparation of the selective layer: Select the polymer polyethersulfone (PES) as the selective layer material. Through the solvent evaporation method, the PES solution is uniformly coated on the surface of the transition layer to form a selective layer with a microporous structure. Preparation of other layers: On the outside of the selective layer, an aramid fiber fabric reinforcement layer, an inorganic filler (a mixture of calcium carbonate and montmorillonite) reinforcement layer, an internal concentration polarization improvement layer, a functional layer (composed of a blend of polyamide-6 and cellulose acetate), a protective layer (perfluoroalkoxy resin), a catalytic layer (iron oxide), and an ion exchange layer (introducing quaternary ammonium salt functional groups through chemical reactions) are sequentially coated. Finally, surface modification is carried out to improve the comprehensive performance of the membrane.

[0072] Design of comparative experiments:

[0073] Experimental materials:

[0074] Composite membranes prepared in Example 1, Example 2, and Example 3;

[0075] Experimental methods:

[0076] Water permeability test: Use a standard water permeation instrument to measure the water flux of each membrane under a certain pressure.

[0077] Selectivity test: Evaluate the selectivity of each membrane by measuring the rejection rate of specific solutes (such as salts).

[0078] Mechanical strength test: Use a tensile testing machine to test the tensile strength and elongation at break of each membrane.

[0079] Anti-fouling test: Expose each membrane to a solution containing pollutants and then measure the change in its water permeability.

[0080] Chemical stability test: Expose each membrane to acid and base solutions and observe the changes in its morphology and performance; Experimental results and comparison

[0081] Water permeability:

[0082] Example 1: Exhibited good water permeability with a relatively high water flux.

[0083] Example 2: The water permeability was slightly lower than that of Example 1 but still within an acceptable range.

[0084] Example 3: Exhibited excellent water permeability with a water flux higher than that of Example 1 and Example 2.

[0085] Optional:

[0086] Example 1: It has a high rejection rate for salts and good selectivity.

[0087] Example 2: The selectivity for specific solutes is high, especially the retention effect for small molecule solutes is good, but it may be too specific in some applications.

[0088] Example 3: It has a good rejection rate for salts and other solutes, good selectivity, and a wider range of applications.

[0089] Mechanical strength:

[0090] Example 1: Due to the use of a fiber fabric reinforcement layer, the mechanical strength of the membrane is higher.

[0091] Example 2: A glass fiber fabric reinforcement layer is used, and the mechanical strength is also high.

[0092] Example 3: Aramid fiber fabric reinforcement layer is used, which has extremely high mechanical strength and excellent durability.

[0093] Anti-pollution:

[0094] Example 1: Surface modification improves the hydrophilicity of the membrane and improves its anti-fouling properties.

[0095] Example 2: Surface modification also improves the hydrophilicity of the membrane and has good anti-fouling properties.

[0096] Example 3: Surface modification and multilayer structure jointly improve the anti-fouling ability of the membrane, and the performance is more excellent.

[0097] Chemical stability:

[0098] Example 1: Stable in acid and alkali solutions.

[0099] Example 2: It is stable in acid and alkali solutions, but may be affected by long-term exposure to strong acids and alkalis.

[0100] Example 3: It is very stable in acid and alkali solutions and has excellent chemical stability.

[0101] Advantages of Example 3

[0102] High water permeability: Suitable for applications with high flow requirements, such as large-scale water treatment or high-speed filtration systems;

[0103] Extremely high mechanical strength: The use of aramid fiber gives the membrane extremely high tensile strength and elongation at break, improving the durability and reliability of the membrane;

[0104] Excellent anti-pollution and chemical stability: The multi-layer structure and surface modification jointly improve the anti-pollution ability of the membrane, and at the same time, the excellent chemical stability enables the membrane to maintain stable performance in harsh environments;

[0105] Example 3 exhibits excellent performance in terms of water permeability, selectivity, mechanical strength, anti-pollution and chemical stability, showing obvious advantages over the other two examples.

[0106] In the present invention, unless otherwise clearly specified and defined, terms such as "installation", "setting", "connection", "fixation", "swivel connection" and the like shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, for those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0107] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A forward osmosis membrane material for effectively improving internal concentration polarization, characterized in that It includes a forward osmosis membrane material, which consists of a membrane substrate, a surface modification layer, an internal concentration polarization improvement layer, a functional layer, a transition layer, a selective layer, a protective layer, a reinforcing layer, a catalytic layer, and an ion exchange layer. A protective layer is provided on the outer side of the membrane substrate, a catalytic layer is provided on the outer side of the protective layer, an ion exchange layer is provided on the outer side of the catalytic layer, a reinforcing layer is provided on the outer side of the ion exchange layer, a porous support layer is provided on the outer side of the reinforcing layer, a transition layer is provided on the outer side of the porous support layer, an internal concentration polarization improvement layer is provided on the outer side of the transition layer, a functional layer is provided on the outer side of the internal concentration polarization improvement layer, a selective layer is provided on the outer side of the functional layer, and a surface modification layer is provided on the outer side of the selective layer.

2. An osmotic membrane material for effectively improving internal concentration polarization according to claim 1, characterized in that: The membrane substrate is made of a blend material of polylactic acid and polyhydroxyalkanoate. The surface modification layer is a small molecule compound containing hydrophilic groups. The internal concentration polarization improvement layer is made of MOFs, COFs, and nanowires, where the mass ratio of MOFs, COFs, and nanowires is 3 - 1:2 - 1:4 - 1. The MOFs, COFs, and nanowires are compounded by an electrostatic self-assembly method. The functional layer is made of a blend material of polyamide and cellulose acetate. The transition layer is made of a blend material of inorganic nanoparticles and polymers. The electrostatic self-assembly method specifically includes the following steps: F1. Disperse MOFs and COFs particles in an aqueous solution containing a specific surfactant, and perform ultrasonic treatment to make them uniformly dispersed to form a stable dispersion. F2. Disperse the nanowires in another aqueous solution containing a surfactant with an opposite charge, and also perform ultrasonic treatment to form a nanowire dispersion. F3. Mix the two dispersions, and perform an electrostatic self-assembly reaction at a specific temperature and stirring speed. The reaction time is 1 - 3 h. F4. After the reaction is completed, obtain the MOFs, COFs, and nanowire composite through steps such as centrifugation, washing, and drying.

3. An osmotic membrane material for effectively improving internal concentration polarization according to claim 2, characterized in that: The selective layer is made of a high molecular polymer or an inorganic material. The protective layer is made of one of polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and perfluoroalkoxy resin.

4. An osmotic membrane material for effectively improving internal concentration polarization according to claim 3, characterized in that: The reinforcing layer is one of a fiber fabric, a grid, and an inorganic filler. The catalytic layer is a metal oxide, and a catalytically active nanozyme is loaded in the catalytic layer. This nanozyme can catalytically degrade the intercepted organic matter during the forward osmosis process. The ion exchange layer is made of sulfonic acid groups, carboxyl groups, and quaternary ammonium salts. The forward osmosis membrane material adopts a preparation method combining 3D printing and in-situ growth. First, precisely construct the preliminary structure of the membrane material through 3D printing technology, and then perform in-situ growth under specific conditions to make each layer of material tightly combined and the structure uniform. The 3D printing technology adopts photocuring 3D printing, and the printing accuracy is 10 - 50 microns. The conditions for in-situ growth are in a specific solution at 60 - 90 °C, and the reaction time is 12 - 24 h.

5. An osmotic membrane material for effectively improving internal concentration polarization according to claim 4, characterized in that: The preparation method of the membrane substrate specifically includes the following steps: A1. Weigh polylactic acid and polyhydroxyalkanoate, and prepare the weighed polylactic acid and polyhydroxyalkanoate by melt blending. A2. Dry polylactic acid and polyhydroxyalkanoate to reduce the moisture content. A3. After drying, put them into a high-speed mixer to mix evenly, and then add them into a twin-screw extruder to carry out modified granulation at a temperature of 120 - 180 °C. A4. Add the modified resin into a blown film machine to blow film, and then the film substrate can be obtained.

6. The forward osmosis membrane material for effectively improving internal concentration polarization according to claim 5, characterized in that: The preparation method of the transition layer specifically includes the following steps: B1. Measure inorganic nanoparticles and disperse them evenly in a pre-prepared polymer solution to ensure that there is no agglomeration between particles. B2. Adopt a precision doctor blade coating process, and evenly and continuously scrape the mixed solution on the surface of the substrate with a doctor blade. After the solvent volatilizes, a transition layer is formed.

7. An osmotic membrane material for effectively improving internal concentration polarization according to claim 6, characterized in that: The preparation method of the selective layer specifically includes the following steps: C1. The polymer selective layer is prepared by solvent evaporation method to form a selective layer with a microporous structure to block macromolecules or ions. C2. The inorganic material selective layer is prepared by chemical vapor deposition method to form a selective layer with a microporous structure to block macromolecules or ions.

8. An osmotic membrane material for effectively improving internal concentration polarization according to claim 7, characterized in that: The preparation method of the reinforcing layer specifically includes the following steps: D1. Fibers form a fiber fabric through weaving technology. D2. For inorganic fillers, they need to be mixed evenly with a binder first. D3. After mixing evenly, through a compression molding process, use high pressure to tightly bond the mixture to the surface of the substrate. After curing treatment, the inorganic filler and the fiber fabric combine to form a strong reinforcing layer.

9. An osmotic membrane material for effectively improving internal concentration polarization according to claim 8, characterized in that: The preparation method of the ion exchange layer specifically includes the following steps: E1. Introduce sulfonic acid groups and carboxyl functional groups on the surface of the membrane material by chemical reaction. E2. The functional groups carry exchangeable ions, which can displace other ions in the solution, thereby endowing the membrane material with ion exchange ability to obtain an ion exchange layer.

10. Application of the forward osmosis membrane material for effectively improving internal concentration polarization according to any one of claims 1 - 9 in industrial wastewater treatment.