Hollow fiber composite membrane, method for preparing the same, and use thereof

Abstract

This invention relates to hollow fiber composite membranes, their preparation methods, and applications. The preparation method includes the following steps: providing a meta-aramid hollow fiber base membrane; preparing a crosslinking solution by mixing bisphenol A type water-soluble epoxy resin, a water-based amine curing agent, a polysaccharide compound, a water-soluble humectant, and water, wherein the mass ratio of bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:15-100:30; modifying the surface of the meta-aramid hollow fiber base membrane using the crosslinking solution, and forming a crosslinked layer through heat treatment to obtain the hollow fiber composite membrane; before modifying the surface of the meta-aramid hollow fiber base membrane using the crosslinking solution, controlling the water mass fraction in the meta-aramid hollow fiber base membrane to be 45%-70%. The hollow fiber composite membrane prepared by this method possesses excellent dye / salt separation performance, high operational stability, and high water flux, making it better suited for dye wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of separation membrane technology, and in particular to hollow fiber composite membranes, their preparation methods, and applications. Background Technology

[0002] The textile industry is one of my country's pillar industries, but it is also a typical high-water-consuming industry, requiring nearly 100 million tons of softened water for process use annually. Its dyeing and printing wastewater has complex sources and variable pollutant composition, characterized by large fluctuations in water quality, high organic content, and high color (mainly from colored dyes). Direct discharge would seriously harm the ecological environment and human health, while also causing a huge waste of water resources. Nanofiltration membranes, due to their unique pore size and charge characteristics, possess advantages such as low operating pressure and high permeation flux. They exhibit different selectivities for monovalent and divalent ions and can efficiently retain small-molecule organic matter, and have been widely used in drinking water treatment, dye wastewater treatment, and resource recovery.

[0003] Hollow fiber nanofiltration membranes, among others, possess advantages such as large water treatment capacity, large specific surface area, and backwashability, effectively improving their antifouling ability and extending their service life. However, when treating dye wastewater, existing hollow fiber nanofiltration membranes retain inorganic salts along with dyes, leading to ineffective separation of dyes and salts. Furthermore, most existing hollow fiber nanofiltration membranes are composed of a base membrane and a separation layer formed by interfacial polymerization. The interfacial bonding between the base membrane and the separation layer is typically weak, making the separation layer prone to peeling during long-term operation or backwashing, thus affecting the operational stability of the hollow fiber nanofiltration membrane. In addition, existing hollow fiber nanofiltration membranes still suffer from low water flux. Summary of the Invention

[0004] Therefore, it is necessary to provide a hollow fiber composite membrane, its preparation method, and its application to address the above problems. The hollow fiber composite membrane prepared by this method has excellent dye / salt separation performance, high operational stability, and high water flux, and can be better applied to dye wastewater treatment.

[0005] A method for preparing a hollow fiber composite membrane includes the following steps:

[0006] Provide meta-aramid hollow fiber base membranes;

[0007] A crosslinking liquid is prepared by combining a bisphenol A type water-soluble epoxy resin, a water-based amine curing agent, a polysaccharide compound, a water-soluble humectant, and water, wherein the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:15-100:30.

[0008] The surface of the meta-aramid hollow fiber base membrane is modified using the crosslinking solution, and a crosslinking layer is formed by heat treatment to obtain a hollow fiber composite membrane. Before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 45%-70%.

[0009] In one embodiment, the mass fraction of the bisphenol A type water-soluble epoxy resin in the crosslinking liquid is 0.5%-1.5%;

[0010] And / or, the mass fraction of the aqueous amine curing agent in the crosslinking liquid is 0.1%-0.5%;

[0011] And / or, the mass fraction of the polysaccharide compound in the crosslinking solution is 0.2%-2%;

[0012] And / or, the mass fraction of the water-soluble moisturizer in the crosslinking solution is 5%-10%.

[0013] In one embodiment, the epoxy equivalent in the bisphenol A type water-soluble epoxy resin is 200 g / eq-500 g / eq;

[0014] And / or, the water-based amine curing agent is selected from water-soluble amine low-temperature curing agents, and the amine value of the water-soluble amine low-temperature curing agent is 180mgKOH / g-350mgKOH / g;

[0015] And / or, the polysaccharide compound has a molecular weight of 100,000 Da to 200,000 Da, and the polysaccharide compound is selected from at least one of hydroxyethyl cellulose, sodium alginate or sodium carboxymethyl cellulose;

[0016] And / or, the water-soluble moisturizer is selected from glycerol and / or propylene glycol.

[0017] In one embodiment, before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the surface of the meta-aramid hollow fiber base membrane is activated with an alkaline solution, and then the activated meta-aramid hollow fiber base membrane is rinsed with water, drained, and the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 45%-70%, wherein the mass fraction of alkaline compound in the alkaline solution is 0.5%-5%.

[0018] And / or, the heat treatment temperature is 80℃-120℃, and the time is 1min-3min.

[0019] In one embodiment, when the meta-aramid hollow fiber base membrane is a self-supporting meta-aramid hollow fiber base membrane, the wall thickness of the self-supporting meta-aramid hollow fiber base membrane is 200μm-300μm.

[0020] In one embodiment, when the meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, the reinforced meta-aramid hollow fiber base membrane includes a support tube and a meta-aramid membrane composited on the surface of the support tube.

[0021] In one embodiment, the preparation method of the reinforced meta-aramid hollow fiber base membrane includes the following steps: mixing meta-aramid polymer with a first pore-forming agent, a second pore-forming agent, an inorganic salt, and an organic solvent and heating until completely dissolved; after degassing, a casting solution is obtained; the casting solution is applied to the surface of a support tube through a spray nozzle, cured into a film in a coagulation bath, and then rinsed to obtain the reinforced meta-aramid hollow fiber base membrane, wherein the molecular weight of the first pore-forming agent is less than or equal to 1000 Da, and the molecular weight of the second pore-forming agent is greater than or equal to 10000 Da;

[0022] And / or, the thickness of the meta-aramid film is 60 μm-120 μm;

[0023] And / or, the outer diameter of the support tube is 0.8mm-1.4mm;

[0024] And / or, the material of the support tube is selected from polyester fiber.

[0025] In one embodiment, in the casting solution, the mass fraction of the meta-aramid polymer is 8%-16.5%, the mass fraction of the first pore-forming agent is 1%-8.5%, the mass fraction of the second pore-forming agent is 1%-3.5%, and the mass fraction of the inorganic salt is 1.5%-7.5%.

[0026] And / or, the first pore-forming agent is selected from at least one of polyethylene glycol, propylene glycol, glycerol or diethylene glycol;

[0027] And / or, the second pore-forming agent is selected from polyvinylpyrrolidone and / or polyethylene oxide;

[0028] And / or, the inorganic salt is selected from lithium chloride and / or calcium chloride.

[0029] A hollow fiber composite membrane prepared by the aforementioned method.

[0030] Application of the hollow fiber composite membrane described above in dye wastewater treatment equipment.

[0031] In the preparation method of the hollow fiber composite membrane of the present invention, when the surface of the base membrane is modified by crosslinking liquid and then heated, the bisphenol A type water-soluble epoxy resin in the crosslinking liquid undergoes a ring-opening addition reaction with the water-based amine curing agent to form a three-dimensional network structure crosslinked layer. By controlling the mass ratio of the two, the three-dimensional network structure has a low crosslinking density, thereby obtaining a loosely structured crosslinked layer. At the same time, under the catalysis of the water-based amine curing agent, on the one hand, the active NH bond in the amide bond on the surface of the meta-aramid hollow fiber base membrane undergoes a ring-opening addition reaction with the epoxy group of the bisphenol A type water-soluble epoxy resin. The formation of high-energy and stable CN bonds significantly enhances the bonding force between the base membrane and the crosslinking layer, ensuring the long-term operational stability of the composite membrane. On the other hand, the hydroxyl groups in the polysaccharide molecules in the crosslinking solution undergo ring-opening addition reactions with the epoxy groups of the bisphenol A type water-soluble epoxy resin to form CO bonds, grafting the hydrophilic polysaccharide into the three-dimensional network structure to construct a continuous hydrophilic three-dimensional network structure, thereby ultimately obtaining a hydrophilic and loose crosslinking layer. This crosslinking layer allows for the effective retention of dyes with larger molecular weights, while small molecule inorganic salts can easily permeate, thus achieving efficient separation of dyes and salts.

[0032] In addition, by controlling the mass fraction of water in the meta-aramid hollow fiber base membrane, the membrane pores can be effectively protected while controlling the penetration depth of the crosslinking liquid on the base membrane surface, avoiding excessive penetration of the crosslinking liquid and clogging of the base membrane pores, thereby maintaining the overall permeability of the base membrane and ensuring that the hollow fiber composite membrane has a high water flux. Moreover, the water-soluble humectant in the crosslinking liquid can effectively slow down the water evaporation rate during heat treatment, preventing the crosslinking layer from forming closed pores due to excessive dehydration, maintaining the open pore structure, and further improving the water flux of the hollow fiber composite membrane.

[0033] Therefore, the hollow fiber composite membrane prepared by the method of the present invention has excellent dye / salt separation performance, high operational stability and high water flux, and can be better applied to dye wastewater treatment. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 This is an electron microscope image of the cross-section of the hollow fiber composite membrane prepared in Example 1 of the present invention;

[0036] Figure 2 This is an electron microscope image of the hollow fiber composite membrane prepared in Example 1 of the present invention. Detailed Implementation

[0037] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional range of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0039] The method for preparing the hollow fiber composite membrane provided by the present invention includes the following steps:

[0040] Provide meta-aramid hollow fiber base membranes;

[0041] A crosslinking liquid is prepared by combining a bisphenol A type water-soluble epoxy resin, a water-based amine curing agent, a polysaccharide compound, a water-soluble humectant, and water, wherein the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:15-100:30.

[0042] The surface of the meta-aramid hollow fiber base membrane is modified using the crosslinking solution, and a crosslinking layer is formed by heat treatment to obtain a hollow fiber composite membrane. Before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 45%-70%.

[0043] In this invention, a meta-aramid hollow fiber base membrane is used, that is, meta-aramid is used as the main material of the base membrane. Since meta-aramid is a linear macromolecule composed of amide groups linked to meta-phenyl groups, it is a regularly arranged serrated macromolecule. The covalent bonds linked at the meta positions do not have a conjugation effect. Due to the strong effect of hydrogen bonds, the chemical structure of meta-aramid is stable, thus giving the meta-aramid hollow fiber base membrane excellent hydrophilicity, mechanical properties, heat resistance and chemical corrosion resistance, which is beneficial to improving the water flux and operational stability of the hollow fiber composite membrane.

[0044] When the crosslinking solution is used to modify the surface of the meta-aramid hollow fiber base film and a crosslinking layer is formed by heat treatment, during the process, the bisphenol A type water-soluble epoxy resin in the crosslinking solution undergoes a ring-opening addition reaction with the water-based amine curing agent to form a three-dimensional network structure crosslinking layer. By controlling the mass ratio of the two, the three-dimensional network structure has a low crosslinking density, thereby obtaining a loosely structured crosslinking layer. Meanwhile, under the catalysis of water-based amine curing agents, on the one hand, the active NH bonds in the amide bonds on the surface of the meta-aramid hollow fiber base membrane undergo a ring-opening addition reaction with the epoxy groups of the bisphenol A type water-soluble epoxy resin to form CN bonds with high bond energy and strong stability, significantly enhancing the bonding force between the base membrane and the crosslinked layer and ensuring the long-term operational stability of the composite membrane; on the other hand, the hydroxyl groups in the polysaccharide compounds in the crosslinking solution undergo a ring-opening addition reaction with the epoxy groups of the bisphenol A type water-soluble epoxy resin to form CO bonds, grafting hydrophilic polysaccharides into the three-dimensional network structure to construct a continuous hydrophilic three-dimensional network structure, thereby ultimately obtaining a hydrophilic and loose crosslinked layer. This crosslinked layer can effectively retain dyes with larger molecular weights, while small molecule inorganic salts can easily permeate, thus achieving efficient separation of dyes and salts.

[0045] Furthermore, before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, controlling the mass fraction of water in the meta-aramid hollow fiber base membrane can effectively protect the membrane pores while controlling the penetration depth of the crosslinking solution on the base membrane surface. This prevents excessive penetration of the crosslinking solution from clogging the base membrane pores, thereby maintaining the overall permeability of the base membrane and ensuring that the hollow fiber composite membrane has a high water flux. Moreover, the water-soluble humectant in the crosslinking solution can effectively slow down the water evaporation rate during heat treatment, preventing the crosslinked layer from forming closed pores due to excessive dehydration, maintaining the open pore structure, and further improving the water flux of the hollow fiber composite membrane.

[0046] Therefore, the hollow fiber composite membrane prepared by the method of the present invention has excellent dye / salt separation performance, high operational stability and high water flux, and can be better applied to dye wastewater treatment.

[0047] It should be noted that, in the process of preparing the crosslinking solution, although the bisphenol A type water-soluble epoxy resin and the water-based amine curing agent can undergo a crosslinking reaction at room temperature, the reaction rate is relatively slow in aqueous solution. Therefore, in the prepared crosslinking solution, both mainly exist in an unreacted form, and the crosslinking reaction mainly occurs during the subsequent heat treatment process.

[0048] In this invention, the meta-aramid hollow fiber base membrane can be a self-supporting hollow fiber meta-aramid membrane or a reinforced hollow fiber meta-aramid membrane, preferably a reinforced hollow fiber meta-aramid membrane.

[0049] Optionally, when the meta-aramid hollow fiber base membrane is a self-supporting meta-aramid hollow fiber base membrane, the wall thickness of the self-supporting meta-aramid hollow fiber base membrane is 200μm-300μm; it can be understood that the self-supporting meta-aramid hollow fiber base membrane refers to a meta-aramid membrane with a hollow fiber morphology; by controlling its thickness, the pressure resistance stability of the base membrane can be effectively improved.

[0050] Optionally, when the meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, the reinforced meta-aramid hollow fiber base membrane includes a support tube and a meta-aramid membrane composited on the surface of the support tube. It can be understood that, compared with the self-supporting meta-aramid hollow fiber base membrane, the provision of the support tube in the reinforced meta-aramid hollow fiber base membrane can significantly improve the tensile strength and pressure resistance stability of the meta-aramid hollow fiber base membrane, ensuring that the subsequent hollow fiber composite membrane can withstand relatively higher filtration pressure while maintaining the outer diameter of the meta-aramid membrane stable and preventing it from being flattened.

[0051] In one embodiment, the thickness of the meta-aramid film is 60 μm-120 μm.

[0052] Optionally, the outer diameter of the support tube is 0.8mm-1.4mm; by controlling the outer diameter of the support tube, it is beneficial to improve the pressure resistance stability of the meta-aramid hollow fiber base film.

[0053] Optionally, the material of the support tube is preferably polyester fiber.

[0054] In this invention, the preparation method of meta-aramid hollow fiber base membrane is not particularly limited. In one embodiment, meta-aramid hollow fiber base membrane is prepared by a non-solvent phase separation method.

[0055] Specifically, when the meta-aramid hollow fiber base membrane is a self-supporting meta-aramid hollow fiber base membrane, the preparation method of the self-supporting meta-aramid hollow fiber base membrane includes the following steps: mixing the meta-aramid polymer with a first pore-forming agent, a second pore-forming agent, an inorganic salt, and an organic solvent and heating until completely dissolved, then degassing to obtain a casting solution; extruding the casting solution and the core solution through an annular nozzle into a coagulation bath, and then solidifying through phase separation to obtain a self-supporting meta-aramid hollow fiber base membrane, wherein the molecular weight of the first pore-forming agent is less than or equal to 1000 Da, and the molecular weight of the second pore-forming agent is greater than or equal to 10000 Da.

[0056] In one embodiment, in the step of mixing the meta-aramid polymer with a first pore-forming agent, a second pore-forming agent, an inorganic salt, and an organic solvent and heating until completely dissolved, the heating temperature is 70°C-85°C.

[0057] In one embodiment, the coagulation bath is selected from water or a mixed solution containing a non-aqueous solvent and water, wherein the mass fraction of the non-aqueous solvent in the mixed solution is ≤50%, and the temperature of the coagulation bath is 40°C-60°C.

[0058] In one embodiment, the core fluid is a mixed solution formed by a solvent and a non-solvent, wherein the solvent is selected from at least one of N,N-dimethylacetamide, N-methylpyrrolidone, and γ-butyrolactone; and the non-solvent is water.

[0059] When the meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, the preparation method of the reinforced meta-aramid hollow fiber base membrane includes the following steps: mixing the meta-aramid polymer with a first pore-forming agent, a second pore-forming agent, an inorganic salt, and an organic solvent and heating until completely dissolved, then degassing to obtain a casting solution; applying the casting solution to the surface of a support tube through a spray nozzle, curing it into a film in a coagulation bath, and then rinsing to obtain the reinforced meta-aramid hollow fiber base membrane, wherein the molecular weight of the first pore-forming agent is less than or equal to 1000 Da, and the molecular weight of the second pore-forming agent is greater than or equal to 10000 Da.

[0060] In one embodiment, pure water is used for rinsing, wherein the rinsing temperature is 35°C-50°C.

[0061] Optionally, in the casting solution, the mass fraction of the meta-aramid polymer is 8%-16.5%, the mass fraction of the first pore-forming agent is 1%-8.5%, the mass fraction of the second pore-forming agent is 1%-3.5%, and the mass fraction of the inorganic salt is 1.5%-7.5%. This configuration, by controlling the mass fraction of each component in the casting solution, helps to ensure that the prepared meta-aramid hollow fiber membrane maintains high mechanical strength while possessing high flux, suitable pore size, and good structural uniformity. This, in turn, helps to improve the overall permeation, operational stability, and separation efficiency of dyes and salts in the hollow fiber composite membrane.

[0062] Further, the first pore-forming agent is selected from at least one of polyethylene glycol, propylene glycol, glycerol, or diethylene glycol; the second pore-forming agent is selected from polyvinylpyrrolidone and / or polyethylene oxide, preferably polyvinylpyrrolidone; and the inorganic salt is selected from lithium chloride and / or calcium chloride.

[0063] It should be noted that in the present invention, the casting solution formulation and dissolution conditions used in the preparation methods of the self-supporting meta-aramid hollow fiber base film and the reinforced meta-aramid hollow fiber base film are the same, as are the composition and temperature conditions of the coagulation bath.

[0064] In this invention, the mass fraction of the bisphenol A type water-soluble epoxy resin in the crosslinking solution is 0.5%-1.5%; the mass fraction of the water-based amine curing agent in the crosslinking solution is 0.1%-0.5%. By controlling the mass fractions of the bisphenol A type water-soluble epoxy resin and the water-based amine curing agent in the crosslinking solution, the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent can be effectively controlled within a specific range, thereby facilitating the obtaining of a crosslinked layer with a loose structure and better achieving efficient separation of dyes and inorganic salts.

[0065] In this invention, the epoxy equivalent in the bisphenol A type water-soluble epoxy resin is 200 g / eq-500 g / eq. This setting allows for effective control of the reaction rate and crosslinking density between the bisphenol A type water-soluble epoxy resin and the water-based amine curing agent by controlling the epoxy equivalent in the bisphenol A type water-soluble epoxy resin. This helps ensure that the crosslinked layer has sufficient mechanical strength and chemical stability while also possessing a suitable loose structure and hydrophilicity, thereby synergistically improving the dye / salt separation efficiency, water flux, and long-term operational stability of the hollow fiber composite membrane.

[0066] It should be noted that in this invention, the bisphenol A type water-soluble epoxy resin can be prepared by conventional methods or can be purchased directly from the market.

[0067] Optionally, the water-based amine curing agent is selected from water-soluble amine low-temperature curing agents, and the amine value of the water-soluble amine low-temperature curing agent is 180mgKOH / g-350mgKOH / g.

[0068] Furthermore, the water-soluble amine low-temperature curing agent is selected from modified fatty amines and / or polyether amine curing agents, wherein the modified fatty amine is preferably a water-soluble polyether diamine and / or a polyoxyethylene modified water-soluble fatty amine.

[0069] Optionally, the mass fraction of the polysaccharide compound in the crosslinking solution is 0.2%-2%. This configuration allows for effective control of the hydroxyl content by adjusting the mass fraction of the polysaccharide compound in the crosslinking solution. On one hand, the hydroxyl groups undergo ring-opening addition reactions with the epoxy groups, grafting hydrophilic polysaccharide segments onto the three-dimensional network, which improves the hydrophilicity of the crosslinking layer, thereby enhancing the water flux and antifouling properties of the hollow fiber composite membrane. On the other hand, the grafted hydrophilic polysaccharide segments utilize their steric hindrance effect, synergistically working with the low crosslinking density achieved by controlling the mass ratio of epoxy resin to amine curing agent, resulting in a relatively loose structure in the crosslinking layer. This allows monovalent inorganic salts to easily permeate, while dyes with larger molecular weights are still efficiently retained, achieving efficient separation of dyes and salts by the hollow fiber composite membrane.

[0070] In this invention, the molecular weight of the polysaccharide compound is 100,000 Da to 200,000 Da. By controlling the molecular weight of the polysaccharide compound within a suitable range, the crosslinking layer can be better formed into a loose hydrophilic structure through appropriate steric hindrance and hydration expansion, while ensuring the grafting efficiency and mechanical strength of the crosslinking layer. This results in high water flux, dye / salt separation performance, and long-term operational stability of the hollow fiber composite membrane.

[0071] Furthermore, the polysaccharide compound is selected from at least one of hydroxyethyl cellulose, sodium alginate, or sodium carboxymethyl cellulose.

[0072] Optionally, the mass fraction of the water-soluble humectant in the crosslinking liquid is 5%-10%. By controlling the mass fraction of the water-soluble humectant, the rate of water evaporation can be better controlled, preventing the crosslinking layer from forming closed pores due to excessive dehydration, maintaining the open pore structure, and further improving the water flux of the hollow fiber composite membrane.

[0073] Furthermore, the water-soluble moisturizer is selected from glycerol and / or propylene glycol, preferably glycerol.

[0074] In this invention, before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the surface of the meta-aramid hollow fiber base membrane is activated with an alkaline solution, followed by rinsing with water, draining, and controlling the water mass fraction in the meta-aramid hollow fiber base membrane to be 45%-70%. This arrangement, by activating the surface of the meta-aramid hollow fiber base membrane with an alkaline solution, partially hydrolyzes the amide bonds on the surface of the meta-aramid hollow fiber base membrane, generating active groups such as amino and carboxyl groups, thereby effectively activating the meta-aramid fibers. The surface of the hollow fiber base membrane is activated to allow it to undergo ring-opening addition reactions with the epoxy groups in the crosslinking solution under the catalysis of the aqueous amine curing agent in the subsequent crosslinking solution, forming covalent bonds. This significantly enhances the interfacial bonding between the crosslinked layer and the meta-aramid hollow fiber base membrane, preventing the crosslinked layer from peeling off during long-term operation. At the same time, the surface activation treatment of the meta-aramid hollow fiber base membrane can also improve its surface hydrophilicity, which is beneficial to the uniform coating of the crosslinking solution and promotes the full progress of the crosslinking reaction at the interface, thereby further improving the operational stability, water flux, and dye and salt separation performance of the hollow fiber composite membrane.

[0075] Optionally, the mass fraction of the alkaline compound in the alkaline solution is 0.5%-5%. By controlling the mass fraction of the alkaline compound in the alkaline solution, the activation level of the meta-aramid hollow fiber membrane surface can be effectively regulated. On the one hand, this provides sufficient active groups to enhance the covalent anchoring force between the crosslinked layer and the meta-aramid hollow fiber membrane, thereby improving the operational stability of the hollow fiber composite membrane. On the other hand, it avoids excessive hydrolysis from damaging the meta-aramid hollow fiber membrane, maintaining its good mechanical properties and permeability, thus synergistically improving the separation performance and water flux of the hollow fiber composite membrane.

[0076] Furthermore, the alkaline compound is preferably sodium hydroxide and / or potassium hydroxide.

[0077] In one embodiment, the activation treatment time is 3 min to 10 min.

[0078] Optionally, the heat treatment temperature is 80℃-120℃ and the time is 1min-3min. By controlling the temperature and time of the heat treatment, the active groups on the surface of the bisphenol A type water-soluble epoxy resin, water-based amine curing agent, polysaccharide compound, and meta-aramid hollow fiber base membrane in the crosslinking solution can be effectively crosslinked, thereby improving the integrity of the crosslinked layer and improving the separation performance, operational stability, and water flux of the hollow fiber composite membrane.

[0079] In one embodiment, the preferred time for modifying the surface of the meta-aramid hollow fiber base film with the crosslinking liquid is 0.5 min to 1.5 min.

[0080] In one embodiment, the specific steps for modifying the surface of the meta-aramid hollow fiber base film with the crosslinking liquid and forming a crosslinked layer by heat treatment are as follows: the meta-aramid hollow fiber base film is released from the unwinding machine and uniformly coated onto the outer surface of the meta-aramid hollow fiber base film by passing it through a composite nozzle containing the crosslinking liquid; then, excess crosslinking liquid is removed by blowing with an annular air knife; next, it is heat-treated in an oven; finally, it is wound up by a winding machine.

[0081] In one embodiment, the unwinding machine speed is 2m / min-10m / min, and the pressure of the annular air knife blowing is 0.01MPa-0.1MPa.

[0082] In one embodiment, the temperature of the composite nozzle is 50°C-70°C.

[0083] Furthermore, this invention also provides a hollow fiber composite membrane prepared using the method described above. This hollow fiber composite membrane possesses excellent dye / salt separation performance, high operational stability, and high water flux, making it better suited for dye wastewater treatment.

[0084] In addition, the present invention also provides an application of the hollow fiber composite membrane as described above in a dye wastewater treatment device.

[0085] The hollow fiber composite membrane, its preparation method, and its applications will be further described below through specific embodiments. However, those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified, specific conditions in the embodiments are performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0086] Example 1

[0087] Meta-aramid polymer was mixed with glycerol, polyvinylpyrrolidone, lithium chloride, and dimethylacetamide and heated to 80°C. The mixture was stirred until completely dissolved, and then degassed to obtain a homogeneous casting solution. The casting solution contained 12% meta-aramid polymer, 5% glycerol, 1.5% polyvinylpyrrolidone, and 3% lithium chloride by mass. Bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 200 g / eq) and a water-based amine curing agent were also mixed. A crosslinking solution was prepared by uniformly mixing water-soluble polyether diamine (amine value 300 mg KOH / g), hydroxyethyl cellulose (molecular weight 100,000 Da), glycerol, and water. In the crosslinking solution, the mass fraction of the bisphenol A type water-soluble epoxy resin was 0.5%, the mass fraction of the water-based amine curing agent was 0.12%, the mass fraction of the hydroxyethyl cellulose was 0.6%, the mass fraction of the glycerol was 6%, and the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent was 100:24.

[0088] The above-mentioned casting solution is applied to the surface of a polyester support tube (outer diameter of 1 mm) through a spray nozzle, and then drawn into a coagulation bath for curing. The coagulation bath is a mixed solution of water and dimethylacetamide, and the mass fraction of dimethylacetamide in the mixed solution is 30%. The temperature of the coagulation bath is 50°C. Then, it is rinsed in water at 40°C, and the filaments are wound into a basket without breaking to obtain a meta-aramid hollow fiber base membrane. After soaking in pure water, it is ready for use. The meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, which includes a polyester support tube and a meta-aramid membrane composited on the surface of the support tube. The wall thickness of the meta-aramid membrane is 70 μm.

[0089] The meta-aramid hollow fiber base membrane was immersed in a sodium hydroxide aqueous solution for 6 minutes, wherein the mass fraction of sodium hydroxide in the aqueous solution was 1%. It was then rinsed with pure water and drained, with the mass fraction of water in the meta-aramid hollow fiber base membrane controlled at 65%. The meta-aramid hollow fiber base membrane was then unwound at a speed of 3 m / min and passed through a composite nozzle containing crosslinking liquid. After a 1-minute stroke, the crosslinking liquid was uniformly coated onto the outer surface of the meta-aramid hollow fiber base membrane, wherein the temperature of the composite nozzle was 50℃. Excess crosslinking liquid was then removed by blowing with an annular air knife at a pressure of 0.03 MPa. Finally, it was heat-treated in an oven at 90℃ for 3 minutes. After winding, the membrane was obtained as shown in the image. Figure 1 and Figure 2 The hollow fiber composite membrane shown.

[0090] Example 2

[0091] Meta-aramid polymer was mixed with polyethylene glycol 400, polyvinylpyrrolidone, lithium chloride, and dimethylacetamide and heated to 80°C. The mixture was stirred until completely dissolved, and then degassed to obtain a homogeneous casting solution. The casting solution contained 11.5% meta-aramid polymer, 2% polyethylene glycol 400, 2% polyvinylpyrrolidone, and 6% lithium chloride. Bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent 200 g / eq) was also used. A crosslinking liquid is prepared by uniformly mixing a water-based amine curing agent (water-soluble polyether diamine with an amine value of 300 mg KOH / g), sodium alginate, glycerol, and water. In the crosslinking liquid, the mass fraction of the bisphenol A type water-soluble epoxy resin is 1%, the mass fraction of the water-based amine curing agent is 0.3%, the mass fraction of sodium alginate (molecular weight of 200,000 Da) is 1.5%, and the mass fraction of glycerol is 8%. The mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:30.

[0092] The casting solution described above is applied to the surface of a polyester support tube (outer diameter of 1.2 mm) through a spray nozzle, and then drawn into a coagulation bath for curing. The coagulation bath is a mixed solution of water and dimethylacetamide, with a mass fraction of 30% for dimethylacetamide, and the temperature of the coagulation bath is 50°C. The membrane is then rinsed in water at 40°C, and wound into a basket without breaking the fibers to obtain a meta-aramid hollow fiber base membrane. After soaking in pure water, the membrane is ready for use. The meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, which includes a polyester support tube and a meta-aramid membrane composited on the surface of the support tube. The meta-aramid membrane has a wall thickness of 100 μm.

[0093] The meta-aramid hollow fiber base membrane was immersed in a sodium hydroxide aqueous solution for 10 minutes, wherein the mass fraction of sodium hydroxide in the aqueous solution was 0.5%. It was then rinsed with pure water and drained, with the mass fraction of water in the meta-aramid hollow fiber base membrane controlled at 50%. The meta-aramid hollow fiber base membrane was then unwound at a speed of 3 m / min and passed through a composite nozzle containing crosslinking liquid. After a 1-minute stroke, the crosslinking liquid was uniformly coated onto the outer surface of the meta-aramid hollow fiber base membrane, wherein the temperature of the composite nozzle was 70℃. Excess crosslinking liquid was then removed by blowing with an annular air knife at a pressure of 0.05 MPa. Finally, it was heat-treated in an oven at 110℃ for 1.5 minutes, and then wound up to obtain a hollow fiber composite membrane.

[0094] Example 3

[0095] Meta-aramid polymer was mixed with propylene glycol, polyethylene oxide, calcium chloride, and dimethylacetamide and heated to 80°C. The mixture was stirred until completely dissolved, and then degassed to obtain a homogeneous casting solution. The casting solution contained 9.5% meta-aramid polymer, 8.5% propylene glycol, 3.5% polyethylene oxide, and 1.5% calcium chloride by mass. Bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 230 g / eq) and a water-based amine curing agent were also mixed. A crosslinking solution was prepared by uniformly mixing (polyoxyethylene modified water-soluble fatty amine, amine value 350 mg KOH / g), sodium carboxymethyl cellulose, propylene glycol, and water. In the crosslinking solution, the mass fraction of the bisphenol A type water-soluble epoxy resin was 1.5%, the mass fraction of the water-based amine curing agent was 0.5%, the mass fraction of sodium alginate (molecular weight 150,000 Da) was 2%, and the mass fraction of propylene glycol was 10%. The mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent was 3:1.

[0096] The above-mentioned casting solution is applied to the surface of a polyester support tube (outer diameter of 0.8 mm) through a spray nozzle, and then drawn into a coagulation bath for curing. The coagulation bath is a mixed solution of water and dimethylacetamide, and the mass fraction of dimethylacetamide in the mixed solution is 50%. The temperature of the coagulation bath is 40°C. Then, it is rinsed in water at 35°C, and the unbroken fibers are wound into a basket to obtain a meta-aramid hollow fiber base membrane. After soaking in pure water, it is ready for use. The meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, which includes a polyester support tube and a meta-aramid membrane composited on the surface of the support tube. The wall thickness of the meta-aramid membrane is 80 μm.

[0097] The meta-aramid hollow fiber base membrane was immersed in a potassium hydroxide aqueous solution for 3 minutes, wherein the mass fraction of potassium hydroxide in the aqueous solution was 10%. It was then rinsed with pure water and drained, with the mass fraction of water in the meta-aramid hollow fiber base membrane controlled at 70%. The meta-aramid hollow fiber base membrane was then unwound at a speed of 3 m / min and passed through a composite nozzle containing crosslinking liquid. After a 1-minute stroke, the crosslinking liquid was uniformly coated onto the outer surface of the meta-aramid hollow fiber base membrane, wherein the temperature of the composite nozzle was 60℃. Excess crosslinking liquid was then removed by blowing with an annular air knife at a pressure of 0.1 MPa. Finally, it was heat-treated in an oven at 120℃ for 1 minute, and then wound up to obtain a hollow fiber composite membrane.

[0098] Example 4

[0099] Example 4 differs from Example 1 only in that, in the step of preparing the crosslinking solution, a bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 180 g / eq) is used instead of a bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 200 g / eq); all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0100] Example 5

[0101] Example 5 differs from Example 1 only in that, in the step of preparing the crosslinking solution, a bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 530 g / eq) is used instead of a bisphenol A type water-soluble epoxy resin (bisphenol A diglycidyl ether, epoxy equivalent of 200 g / eq); all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0102] Example 6

[0103] Compared with Example 1, Example 6 differs only in that maltodextrin (molecular weight of 8000 Da) is used instead of hydroxyethyl cellulose (molecular weight of 100,000 Da) in the step of preparing the crosslinking solution; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0104] Example 7

[0105] Compared with Example 1, Example 7 differs only in that, in the step of preparing the crosslinking solution, high-polymerization-degree polyvinyl alcohol (molecular weight of 280,000 Da) is used instead of hydroxyethyl cellulose (molecular weight of 100,000 Da); all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0106] Example 8

[0107] Compared with Example 1, Example 8 differs only in that the mass fraction of hydroxyethyl cellulose is 0.1% in the step of preparing the crosslinking solution; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0108] Example 9

[0109] Compared with Example 1, Example 9 differs only in that the mass fraction of hydroxyethyl cellulose is 2.5% in the step of preparing the crosslinking solution; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0110] Example 10

[0111] Example 10 differs from Example 1 only in that the mass fraction of glycerol is 4% in the step of preparing the crosslinking solution; all other conditions are the same, resulting in a hollow fiber composite membrane.

[0112] Example 11

[0113] Example 11 differs from Example 1 only in that the mass fraction of glycerol is 12% in the step of preparing the crosslinking solution; all other conditions are the same, resulting in a hollow fiber composite membrane.

[0114] Example 12

[0115] Example 12 differs from Example 1 only in that it does not include the step of immersing the meta-aramid hollow fiber base membrane in an aqueous sodium hydroxide solution for 6 minutes. Instead, the meta-aramid hollow fiber base membrane is directly drained, and the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 65%. Then, the meta-aramid hollow fiber base membrane is released by an unwinding machine at a speed of 3 m / min. All other conditions are the same, and a hollow fiber composite membrane is obtained.

[0116] Example 13

[0117] Compared with Example 1, Example 13 differs only in that the mass fraction of lithium chloride is 8% in the step of preparing the casting solution; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0118] Comparative Example 1

[0119] Compared with Example 1, Comparative Example 1 differs only in that polyvinylidene fluoride is used instead of meta-aramid polymer in the step of preparing the casting solution; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0120] Comparative Example 2

[0121] Compared with Example 1, Comparative Example 2 differs only in that the preparation of the crosslinking solution does not contain bisphenol A type water-soluble epoxy resin; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0122] Comparative Example 3

[0123] Compared with Example 1, Comparative Example 3 differs only in that the step of preparing the crosslinking liquid does not contain an aqueous amine curing agent; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0124] Comparative Example 4

[0125] Compared with Example 1, Comparative Example 4 differs only in that, in the step of preparing the crosslinking liquid, the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:5; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0126] Comparative Example 5

[0127] Compared with Example 1, Comparative Example 5 differs only in that, in the step of preparing the crosslinking liquid, the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:50; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0128] Comparative Example 6

[0129] Compared with Example 1, Comparative Example 6 differs only in that the preparation of the crosslinking solution does not contain glycerol; all other conditions are the same, resulting in a hollow fiber composite membrane.

[0130] Comparative Example 7

[0131] Compared with Example 1, Comparative Example 7 differs only in that the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 30%; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0132] Comparative Example 8

[0133] Compared with Example 1, Comparative Example 8 differs only in that the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 80%; all other conditions are the same, and a hollow fiber composite membrane is obtained.

[0134] Comparative Example 9

[0135] Comparative Example 9 differs from Example 1 only in that it does not include the step of preparing the crosslinking liquid and passing it through a composite nozzle containing the crosslinking liquid to uniformly coat the outer surface of the meta-aramid hollow fiber base film after a 1-minute stroke. Specifically, the meta-aramid hollow fiber base film is released from the unwinding machine at a speed of 3 m / min and first enters an aqueous phase solution for 1 minute. The aqueous phase solution is prepared by mixing piperazine and water, and the mass fraction of piperazine in the aqueous phase solution is 1.5%. Then, excess aqueous phase solution is blown away by an annular air knife with a pressure of 0.03 MPa. Next, the meta-aramid hollow fiber base film containing the aqueous phase solution is passed through a composite nozzle containing an oil phase solution. The oil phase solution is prepared by mixing trimesoyl chloride, xylene, and n-hexane, and the mass fraction of trimesoyl chloride in the oil phase solution is 0.2% and the mass fraction of xylene is 5%. Finally, it is treated in a 100°C oven for 1 minute and then wound up to obtain a hollow fiber composite film.

[0136] The properties of the hollow fiber composite membranes prepared in Examples 1 to 13 and Comparative Examples 1 to 9 were tested respectively. The test results are shown in Tables 1 and 2. The specific test methods are as follows:

[0137] Membrane water flux (F) and rejection rate (R) test: 2000 mg / L Na2SO4 and 1000 mg / L Congo red solution were used as raw water, and the membrane water flux (F) and rejection rate (R) were measured after running at 0.3 MPa and 25℃ for 0.5 h.

[0138] Operational stability test: After backwashing at 0.3 MPa for 8 hours, the Congo red rejection rate was tested under the above test conditions;

[0139] Tensile strength test: Select a sample membrane filament and clamp it at both ends on the clamps of the universal tensile testing machine. The effective clamping length is 100mm and the tensile rate is 200mm / min. Each sample is tested 5 times and the strength value of the membrane filament is measured in N.

[0140] Table 1

[0141]

[0142] Table 2

[0143]

[0144] It should be noted that in Tables 1 and 2, membrane water flux (F) is the volume (V) of water passing through the effective membrane area (S) per unit time (t) under certain operating conditions, and its unit is L / (m²). 2 h), the calculation formula is: F=V / (S×t), where V is the volume of water passing through the hollow fiber composite membrane in time t, S is the effective membrane area, and t is time.

[0145] Retention rate (R): Under certain operating conditions, the solute concentration (C) of the feed solution f ) and the concentration of solute in the permeate (C p The difference between the feed solution solute concentration (C) and the solute concentration in the feed solution (C) f The ratio of R to C is calculated using the following formula: R = (1 - C) / (1 - C) p / C f ) × 100%.

[0146] Meanwhile, based on the data in Tables 1 and 2, compared to Examples 1 and 4 to 5, it can be seen that controlling the epoxy equivalent in the bisphenol A type water-soluble epoxy resin within a suitable range is beneficial for regulating the crosslinking density and grafting density of the crosslinking layer, thereby obtaining a better crosslinking layer with a hydrophilic and loose structure, and thus improving the water flux, dye / inorganic salt separation performance, and operational stability of the hollow fiber composite membrane. Compared to Examples 1 and 6 to 9, it can be seen that controlling the molecular weight of the polysaccharide compound and the mass fraction of the polysaccharide compound in the crosslinking solution within a suitable range is beneficial for ensuring the grafting efficiency and mechanical strength of the crosslinking layer, while using appropriate steric hindrance and hydration expansion to better form a loose hydrophilic structure in the crosslinking layer, thus better achieving high water flux, dye / salt separation performance, and long-term operational stability of the hollow fiber composite membrane. Compared to Examples 1 and 10 to 11, it can be seen that controlling the mass fraction of the humectant in the crosslinking solution... Within a suitable range, it is beneficial to better ensure the overall permeability of the hollow fiber composite membrane, thereby better achieving high water flux, dye / salt separation performance, and long-term operational stability of the hollow fiber composite membrane. Compared with Examples 1 and 12, it can be seen that using an alkaline solution to activate the surface of the meta-aramid hollow fiber base membrane can effectively activate the active groups on the surface of the meta-aramid hollow fiber base membrane, so that under the catalysis of the water-based amine curing agent, they undergo ring-opening addition reaction with the epoxy groups in the bisphenol A type water-soluble epoxy resin to form covalent bonds, significantly enhancing the interfacial bonding force between the crosslinked layer and the meta-aramid hollow fiber base membrane, preventing the crosslinked layer from peeling off during long-term operation, and improving its surface hydrophilicity, thereby further improving the operational stability, water flux, and dye / salt separation performance of the hollow fiber composite membrane. Compared with Examples 1 and 13, it can be seen that by controlling the mass fraction of inorganic salts in the casting solution, it is beneficial to improve the viscosity system of the casting solution, thereby obtaining higher permeability.

[0147] Compared with Example 1 and Comparative Examples 1 to 9, it can be seen that in the preparation method of the hollow fiber composite membrane of the present invention, by adding bisphenol A type water-soluble epoxy resin, water-based amine curing agent, polysaccharide compound and water-soluble humectant to the crosslinking liquid, and controlling the mass ratio of bisphenol A type water-soluble epoxy resin to water-based amine curing agent, and controlling the mass fraction of water in the meta-aramid hollow fiber base membrane, under this synergistic effect, a hydrophilic and loose crosslinking layer can be obtained while ensuring the overall permeability of the meta-aramid hollow fiber base membrane. Moreover, the crosslinking layer and the meta-aramid hollow fiber base membrane are chemically bonded and have high interfacial bonding force, so that the hollow fiber composite membrane has excellent dye / salt separation performance, high water flux and high operational stability.

[0148] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0149] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for producing a hollow fiber composite membrane, characterized by, Includes the following steps: Provide meta-aramid hollow fiber base membranes; A crosslinking liquid is prepared by combining a bisphenol A type water-soluble epoxy resin, a water-based amine curing agent, a polysaccharide compound, a water-soluble humectant, and water, wherein the mass ratio of the bisphenol A type water-soluble epoxy resin to the water-based amine curing agent is 100:15-100:

30. The surface of the meta-aramid hollow fiber base membrane is modified using the crosslinking solution, and a crosslinking layer is formed by heat treatment to obtain a hollow fiber composite membrane. Before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the mass fraction of water in the meta-aramid hollow fiber base membrane is controlled to be 45%-70%.

2. The method for preparing the hollow fiber composite membrane according to claim 1, characterized in that, The mass fraction of the bisphenol A type water-soluble epoxy resin in the crosslinking solution is 0.5%-1.5%; And / or, the mass fraction of the aqueous amine curing agent in the crosslinking liquid is 0.1%-0.5%; And / or, the mass fraction of the polysaccharide compound in the crosslinking solution is 0.2%-2%; And / or, the mass fraction of the water-soluble moisturizer in the crosslinking solution is 5%-10%.

3. The method for preparing the hollow fiber composite membrane according to claim 1, characterized in that, The epoxy equivalent in the bisphenol A type water-soluble epoxy resin is 200g / eq-500g / eq; And / or, the water-based amine curing agent is selected from water-soluble amine low-temperature curing agents, and the amine value of the water-soluble amine low-temperature curing agent is 180mgKOH / g-350mgKOH / g; And / or, the polysaccharide compound has a molecular weight of 100,000 Da to 200,000 Da, and the polysaccharide compound is selected from at least one of hydroxyethyl cellulose, sodium alginate or sodium carboxymethyl cellulose; And / or, the water-soluble moisturizer is selected from glycerol and / or propylene glycol.

4. The method for preparing the hollow fiber composite membrane according to claim 1, characterized in that, Before modifying the surface of the meta-aramid hollow fiber base membrane with the crosslinking solution, the method further includes activating the surface of the meta-aramid hollow fiber base membrane with an alkaline solution, then rinsing the activated meta-aramid hollow fiber base membrane with water, draining it, and controlling the mass fraction of water in the meta-aramid hollow fiber base membrane to be 45%-70%, wherein the mass fraction of alkaline compound in the alkaline solution is 0.5%-5%. And / or, the heat treatment temperature is 80℃-120℃, and the time is 1min-3min.

5. The method for preparing the hollow fiber composite membrane according to claim 1, characterized in that, When the meta-aramid hollow fiber base membrane is a self-supporting meta-aramid hollow fiber base membrane, the wall thickness of the self-supporting meta-aramid hollow fiber base membrane is 200μm-300μm.

6. The method for preparing the hollow fiber composite membrane according to claim 1, characterized in that, When the meta-aramid hollow fiber base membrane is a reinforced meta-aramid hollow fiber base membrane, the reinforced meta-aramid hollow fiber base membrane includes a support tube and a meta-aramid membrane composited on the surface of the support tube.

7. The method for preparing the hollow fiber composite membrane according to claim 6, characterized in that, The preparation method of the reinforced meta-aramid hollow fiber base membrane includes the following steps: mixing meta-aramid polymer with a first pore-forming agent, a second pore-forming agent, an inorganic salt, and an organic solvent, and heating until completely dissolved, followed by degassing to obtain a casting solution; applying the casting solution to the surface of a support tube through a spray nozzle, curing it into a film in a coagulation bath, and then rinsing to obtain the reinforced meta-aramid hollow fiber base membrane, wherein the molecular weight of the first pore-forming agent is less than or equal to 1000 Da, and the molecular weight of the second pore-forming agent is greater than or equal to 10000 Da; And / or, the thickness of the meta-aramid film is 60 μm-120 μm; And / or, the outer diameter of the support tube is 0.8mm-1.4mm; And / or, the material of the support tube is selected from polyester fiber.

8. The method for preparing the hollow fiber composite membrane according to claim 7, characterized in that, In the casting solution, the mass fraction of the meta-aramid polymer is 8%-16.5%, the mass fraction of the first pore-forming agent is 1%-8.5%, the mass fraction of the second pore-forming agent is 1%-3.5%, and the mass fraction of the inorganic salt is 1.5%-7.5%. And / or, the first pore-forming agent is selected from at least one of polyethylene glycol, propylene glycol, glycerol or diethylene glycol; And / or, the second pore-forming agent is selected from polyvinylpyrrolidone and / or polyethylene oxide; And / or, the inorganic salt is selected from lithium chloride and / or calcium chloride.

9. A hollow fiber composite membrane prepared by the method for preparing a hollow fiber composite membrane according to any one of claims 1 to 8.

10. The application of the hollow fiber composite membrane as described in claim 9 in a dye wastewater treatment device.

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