Recycling of polyester textile waste

Abstract

The invention discloses a method for recycling polyester textile waste. The method comprises the following steps: enabling the textile waste to be in contact with a natural deep eutectic solvent; filtering and separating out undissolved polyester fibers, and cleaning and drying; contacting the dried polyester fibers with an organic solvent mixture; carrying out multi-stage membrane filtration on the dissolved mixture under the protection of inert gas, and carrying out concentration treatment on the filtered solution; dividing the concentrated solution into two parts, adding at least one functional monomer and a photoinitiator into one part to obtain a functional spinning solution, and taking the other part as a basic spinning solution; the functionalized spinning solution and the basic spinning solution are conveyed to an electrostatic field with the voltage of 10-30 kV at the same time, an electric field gradient is formed between a solution conveying area and a fiber collecting area, electric field distribution is adjusted to control deposition of fibers in the collecting area, and a nanofiber membrane is formed in the collecting area. According to the technical scheme, the waste polyester textiles can be converted into products with high added values.

Description

Technical Field

[0001] The invention relates to the technical field of recycling polyester textile waste, in particular to recycling and utilizing polyester textile waste. Background Art

[0002] Polyester textile waste refers to waste materials generated during the production and use of textiles. These wastes are mainly made of polyethylene terephthalate (PET) and are one of the main components of global textile waste. Polyester fibers are widely used in clothing, home textiles and other fields due to their high strength, durability and chemical resistance. However, polyester textiles are difficult to degrade naturally after being discarded, resulting in a large amount of solid waste accumulation and environmental pollution. Therefore, how to effectively recycle polyester textile waste has become one of the important topics in the current environmental protection field.

[0003] The existing treatment of polyester textile waste mainly adopts mechanical recycling, which usually breaks polyester textile waste into recycled fibers by shearing and high-temperature heat treatment. However, this process often leads to a significant decrease in the mechanical properties of the fibers, and the fibers are deformed and broken under stress, and cannot maintain their original strength and toughness. The quality of the final recycled materials is poor and cannot be used in the production of high value-added products. Summary of the invention

[0004] The main purpose of the present invention is to solve the technical problem that the existing mechanical recycling method cannot convert waste polyester textiles into products with high added value.

[0005] A first aspect of the present invention provides a method for recycling polyester textile waste, wherein the recycling of polyester textile waste comprises: contacting the textile waste with a natural deep eutectic solvent, the natural deep eutectic solvent comprising a hydrogen bond acceptor and at least two hydrogen bond donors, and stirring at a predetermined temperature for a predetermined time; filtering and separating the undissolved polyester fibers, and washing and drying the separated polyester fibers; contacting the dried polyester fiber with an organic solvent mixture comprising a halogenated alkane, a fluorine-containing organic acid and a lactone compound; Under the protection of inert gas, the dissolved mixture is subjected to multi-stage membrane filtration, and the filtered solution is concentrated; The concentrated solution is divided into two parts, one part is added with at least one functional monomer and a photoinitiator to obtain a functionalized spinning solution, and the other part is used as a basic spinning solution; The functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV to form an electric field gradient between the solution delivery area and the fiber collection area. The electric field distribution is adjusted to control the deposition of the fibers in the collection area to form a nanofiber membrane in the collection area.

[0006] Optionally, the step of contacting the textile waste with a natural deep eutectic solvent, wherein the natural deep eutectic solvent comprises a hydrogen bond acceptor and at least two hydrogen bond donors, and stirring at a preset temperature for a predetermined time comprises: Cut the textile waste into small pieces of 1-5 cm² and dry them in vacuum at 50°C for 6 hours; A natural deep eutectic solvent is prepared, the preparation steps comprising: selecting choline chloride as a hydrogen bond acceptor, selecting lactic acid and urea as hydrogen bond donors, mixing them in a molar ratio of 1:2:0.5, adding 1wt% of cerium oxide nanocatalyst, and heating the mixture from room temperature to 80°C at a heating rate of 2°C / min under nitrogen protection, and stirring for 2 hours to form a transparent liquid; Mixing the dried textile waste pieces with the prepared natural deep eutectic solvent in a mass ratio of 1:10; The mixture is placed in a temperature-controlled reactor and stirred at a preset temperature for a predetermined time.

[0007] Optionally, the stirring at a preset temperature for a predetermined time includes: The temperature was raised from room temperature to 60 °C at a heating rate of 2 °C / min and maintained at a stirring speed of 600 rpm for 1 h; Continue to increase the temperature to 80°C at a rate of 1°C / min and maintain at a stirring speed of 800 rpm for 2 hours; Finally, the temperature was lowered to 70°C at a rate of 1°C / min and maintained at a stirring speed of 700 rpm for 1 hour.

[0008] Optionally, filtering and separating the undissolved polyester fibers, and washing and drying the separated polyester fibers, comprises: The reaction mixture is subjected to solid-liquid separation using a three-stage series filter, wherein the pore sizes of the three-stage series filter are 50 μm, 30 μm and 10 μm, respectively; The separated polyester fibers were subjected to multi-stage gradient ultrasonic cleaning, specifically comprising: firstly, cleaning with deionized water at a frequency of 40kHz for 20 minutes, then cleaning with ethanol at a frequency of 60kHz for 15 minutes, and finally cleaning with acetone at a frequency of 80kHz for 10 minutes, and the cleaning liquid was removed by centrifugal separation between each stage of cleaning; The cleaned polyester fiber was precooled at -40°C for 2 hours; Freeze drying was performed under a vacuum of 0.01 mbar, first at a heating rate of 1°C / min from -40°C to 0°C and maintained for 6 hours, then at a heating rate of 0.5°C / min to room temperature and maintained for 18 hours; Pulse vacuum drying was performed at 40°C for 2 hours, with a pulse cycle of evacuating to 0.1 mbar for 2 minutes and passing dry nitrogen to normal pressure for 1 minute.

[0009] Optionally, the polyester fiber after the drying treatment is contacted with an organic solvent mixture, wherein the organic solvent mixture contains halogenated alkanes, fluorine-containing organic acids and lactone compounds, including: preparing an organic solvent mixture, comprising: selecting dichloromethane as a halogenated alkane, trifluoroacetic acid as a fluorine-containing organic acid, and γ-butyrolactone as a lactone compound, and mixing them in a volume ratio of 3:6:1; The dried polyester fiber is mixed with the prepared organic solvent mixture at a mass ratio of 1:20; Under nitrogen protection, first dissolve at 60°C for 2 hours, and then continue to dissolve at 80°C for 4 hours; During the dissolution process, the reaction mixture was intermittently sonicated for 1 min every 30 min at a power of 200 W and a frequency of 40 kHz.

[0010] Optionally, the dissolved mixture is subjected to multi-stage membrane filtration under the protection of an inert gas, and the filtered solution is concentrated, comprising: Under the protection of inert gas, the dissolved mixture is filtered through filter membranes with pore sizes of 10 μm, 1 μm and 0.1 μm in sequence; During the filtration process, vibrations of 100-500kHz are applied to the filter membrane; The filtered solution is concentrated at a temperature range of -5°C to 5°C and a pressure of 0.1-1 mbar, and the volatilized solvent is condensed and recovered.

[0011] Optionally, the concentrated solution is divided into two parts, one part of which is added with at least one functional monomer and a photoinitiator to obtain a functionalized spinning solution, and the other part is used as a basic spinning solution, comprising: The concentrated solution is divided into two equal parts; Adding 1-5% by weight of a functional monomer mixture to a portion of the solution, wherein the functional monomer mixture includes a hydrophobic monomer, a hydrophilic monomer and an antibacterial monomer; Adding 0.1-1% of photosensitive nanoparticles as a photoinitiator to the solution to which the functional monomer is added; Stirring the solution to which the functional monomer and the photoinitiator are added at a speed of 300-500 rpm for 30-60 minutes under light-proof conditions to obtain a functionalized spinning solution; Another part of the solution without adding the functional monomer is concentrated under reduced pressure at 60-80° C. for 10-30 minutes to obtain a basic spinning solution.

[0012] Optionally, the functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV, an electric field gradient is formed between the solution delivery area and the fiber collection area, and the electric field distribution is adjusted to control the deposition of the fibers in the collection area to form a nanofiber membrane in the collection area, including: The functionalized spinning solution and the basic spinning solution are respectively delivered through the coaxial nozzles, wherein the functionalized spinning solution is delivered through the inner nozzle and the basic spinning solution is delivered through the outer nozzle; A multi-pole electric field is set between the nozzle and the collector, and a non-uniform electric field distribution is generated by adjusting the voltage of each pole within the range of 10-30kV; A conductive pattern is provided on the surface of the collector, and the conductivity of the conductive pattern is arrive Adjustable within S / m range; During the fiber deposition process, a low-frequency vibration of 50-200 Hz is applied to the collector; During the formation of the nanofiber membrane, the electric field strength and distribution are gradually changed through program control, and the range of change of the electric field strength is an increase or decrease of 1-3 kV every 5 minutes.

[0013] Optionally, after forming the nanofiber membrane in the collection area, the method further comprises: The nanofiber membrane is placed in an environment filled with inert gas and irradiated with ultraviolet light of 280-320 nm wavelength for 10-30 minutes; heat treating the cross-linked nanofiber membrane at 50-70° C. for 2-4 hours; The heat-treated nanofiber membrane is immersed in a nano-titanium dioxide solution with a mass fraction of 0.5-2% for 1-3 hours, and then dried at 80-100° C. for 30-60 minutes.

[0014] Core technical issue: How to efficiently convert complex waste polyester textiles into functional nanofiber materials with high added value while ensuring the environmental friendliness and economic feasibility of the entire process.

[0015] The technical solution provided in the embodiment of the present application enables the polyester fibers to be separated under mild conditions without being damaged by contacting textile waste with a natural deep eutectic solvent. Natural deep eutectic solvent (NADES) is an environmentally friendly solvent composed of hydrogen bond donors and hydrogen bond acceptors. It has high selectivity and good solubility, and can achieve effective separation of fiber materials under relatively low temperature conditions. Unlike the fiber degradation problem that may occur during mechanical recycling, the present invention completes the extraction of polyester fibers at a lower temperature and a milder environment through a chemical separation step, effectively retaining the physical and chemical properties of polyester fibers. This method not only reduces mechanical damage to the fibers, but also avoids the use of harmful chemicals through the selective design of the solvent, thereby improving the environmental friendliness and economic feasibility of the process.

[0016] The present application further improves the added value of the reuse of polyester textile waste through multi-stage membrane filtration and electrostatic spinning technology. In the filtration stage, the dissolved polyester fibers can be effectively separated through the step-by-step treatment of the multi-stage filtration membrane to ensure the thorough removal of impurities, which greatly improves the purity and quality of the final regenerated fibers. The subsequent electrostatic spinning process allows the regenerated polyester fibers to be deposited into nanofiber membranes through the action of the electric field, significantly improving the functionality of the material. This nanofiber membrane not only has good mechanical properties, but also can be endowed with multiple functions such as hydrophobicity and antibacterial properties through the introduction of functional monomers, thereby greatly broadening the application field of the regenerated material. Compared with the traditional mechanical recycling method, the technical solution of the present invention not only improves the recycling efficiency of the material, but also solves the defects of poor quality and limited use of the regenerated materials in the prior art through the preparation process of the multifunctional material, truly realizing the transformation of polyester textile waste into high value-added products, and providing a practical solution for the sustainable recycling of discarded textiles. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0018] Figure 1 This is a schematic diagram of an embodiment of the recycling of polyester textile waste in an embodiment of the present invention.

[0019] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0022] In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, "and / or" in the full text includes three solutions. Taking A and / or B as an example, it includes technical solution A, technical solution B, and technical solution that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, which must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0023] An embodiment of the present application provides a method for recycling polyester textile waste. Figure 1 A flow chart of the recycling of polyester textile waste provided in one embodiment of the present application. In this embodiment, the method includes: See also Figure 1 , contacting the textile waste with a natural deep eutectic solvent, wherein the natural deep eutectic solvent comprises a hydrogen bond acceptor and at least two hydrogen bond donors, and stirring at a preset temperature for a predetermined time; In one embodiment of the present invention, the textile waste is contacted with a natural deep eutectic solvent, wherein the natural deep eutectic solvent comprises a hydrogen bond acceptor and at least two hydrogen bond donors, and stirred at a preset temperature for a predetermined time, comprising: cutting the textile waste into small pieces of 1-5 cm², and vacuum drying at 50°C for 6 hours; preparing a natural deep eutectic solvent, the configuration steps comprising: selecting choline chloride as a hydrogen bond acceptor, selecting lactic acid and urea as hydrogen bond donors, mixing them in a molar ratio of 1:2:0.5, adding 1wt% of cerium oxide nanocatalyst, and under nitrogen protection, heating from room temperature to 80°C at a heating rate of 2°C / min, stirring for 2 hours to form a transparent liquid; mixing the dried textile waste pieces with the prepared natural deep eutectic solvent in a mass ratio of 1:10; placing the mixture in a temperature-controllable reactor, and stirring at a preset temperature for a predetermined time.

[0024] Specifically, in this scheme, the textile waste is first cut into small pieces of 1-5 cm², which is to increase the surface area of ​​the textile waste in contact with the solvent to enhance the dissolution efficiency in subsequent treatment. This step will not cause a significant decrease in the mechanical properties of the fiber or deformation and breakage of the fiber under stress as in traditional mechanical recycling. Traditional mechanical recycling methods usually break polyester fibers into smaller particles or fibrous structures through high-intensity shearing, extrusion or grinding. In this process, the fiber will be subjected to severe physical forces, which will destroy the molecular chain structure of the fiber and greatly reduce the mechanical properties of the fiber (such as strength and toughness). The quality of the regenerated fiber material finally produced is poor and cannot meet the needs of high value-added products. Moreover, high-temperature heat treatment in mechanical recycling may further aggravate the deterioration of such mechanical properties, because at high temperatures, the molecular structure of polyester fibers will undergo irreversible changes, reducing its physical properties. In contrast, the operation of cutting the textile waste into small pieces of 1-5 cm² in this scheme is only to increase the surface area of ​​the textile waste, thereby improving the efficiency of the contact between the solvent and the fiber. The force applied during this cutting process is relatively mild, and it is more of a pretreatment step rather than a destructive breakup of the fiber structure. Therefore, such a cutting operation will not cause significant damage to the molecular structure of the polyester fiber, nor will it reduce the mechanical properties of the fiber. In addition, the small pieces of fiber after cutting still maintain their complete fiber morphology, without experiencing the molecular chain breakage caused by shear force, which is significantly different from the "strong crushing" in mechanical recycling. Since there is no high-intensity mechanical force, the fiber can maintain its original strength and toughness during the subsequent dissolution process, which provides a guarantee for the high quality of the recycled material.

[0025] Next, the cut textile waste is vacuum dried at 50°C for 6 hours. The purpose of the drying process is mainly to remove moisture or volatile impurities in the waste to ensure that the subsequent dissolution process will not be affected by moisture. The use of a vacuum environment avoids the risk of fiber oxidation or degradation in high-temperature air, and the temperature of 50°C is relatively low, far below the melting point of polyester fiber (usually around 260°C), so it will not cause damage to the fiber structure.

[0026] The dried textile waste pieces will be mixed with the prepared natural deep eutectic solvent (NADES) at a mass ratio of 1:10. NADES is a green solvent composed of a hydrogen bond acceptor and a hydrogen bond donor. In this scheme, choline chloride is selected as the hydrogen bond acceptor, and lactic acid and urea are selected as hydrogen bond donors, and they are mixed at a molar ratio of 1:2:0.5. Choline chloride and lactic acid can form a stable hydrogen bond network, which enhances the solvent's ability to dissolve polyester fibers. At the same time, urea further increases the polarity of the solvent by forming additional hydrogen bonds, making the dissolution process more efficient. Compared with traditional mechanical methods, chemical dissolution methods can act more gently on the fiber structure, avoiding damage caused by mechanical force, thereby maintaining the molecular chain integrity of the fiber.

[0027] 1wt% of cerium oxide nanocatalyst is added to the solvent to accelerate the dissolution reaction and reduce the energy required for the reaction. The entire solvent preparation process needs to be carried out under nitrogen protection to prevent oxygen from oxidizing the solvent system. After sufficient stirring, the resulting transparent liquid will have good solubility and can act efficiently on polyester fibers.

[0028] After mixing the dried textile waste pieces with the prepared natural deep eutectic solvent in a mass ratio of 1:10, the entire mixture will be placed in a temperature-controlled reactor and stirred at a preset temperature. The temperature and stirring control in this process can ensure sufficient contact between the fiber and the solvent, so that the polyester fiber can be evenly dissolved. Due to the mildness of the natural deep eutectic solvent and the controllability of the entire process, the molecular structure of the fiber will not be destroyed, thereby maintaining the mechanical properties of the fiber. Ultimately, the dissolution of polyester fiber in the solvent not only avoids the damage problem in mechanical methods, but also achieves efficient dissolution at lower temperatures and less energy consumption, so that the recycled fiber material has high added value.

[0029] In one embodiment of the present invention, the stirring at a preset temperature for a predetermined time includes: heating from room temperature to 60°C at a heating rate of 2°C / min, and maintaining at a stirring speed of 600rpm for 1 hour; continuing to heat to 80°C at a heating rate of 1°C / min, and maintaining at a stirring speed of 800rpm for 2 hours; and finally cooling to 70°C at a cooling rate of 1°C / min, and maintaining at a stirring speed of 700rpm for 1 hour.

[0030] Specifically, the temperature is raised from room temperature to 60°C at a rate of 2°C / min. The slow heating in this process can not only avoid thermal damage to the polyester fiber, but also gradually increase the interaction between the solvent and the fiber, promoting the uniform dissolution of the fiber. 60°C is selected as the intermediate temperature point because the fluidity of the solvent and the solubility of the polyester fiber can reach a balance at this time, which is conducive to the further progress of the subsequent reaction. In addition, too fast a heating rate may cause rapid expansion or even deformation of the fiber, while too slow a heating rate may lead to a decrease in the dissolution efficiency, so a heating rate of 2°C / min is used.

[0031] After reaching 60°C, the system was kept at a stirring speed of 600 rpm for 1 hour. The purpose of stirring at this stage was to ensure that the fiber and the solvent were fully mixed and to prevent the fiber from settling or adhering to the wall of the reactor.

[0032] Next, the system continued to heat up to 80°C at a heating rate of 1°C / min. Compared with the previous heating rate of 2°C / min, the heating rate in this stage was slowed down in order to further and steadily improve the solvent's solubility without causing thermal stress concentration in the fiber. The reaction temperature of 80°C is one of the key temperature points for the dissolution of polyester fibers. At this time, the solvent's solubility reaches its optimal state, and the molecular chains of the polyester fibers are fully expanded in the solvent. The stirring speed of 800rpm can provide stronger shear force to accelerate the dissolution of the fibers, while ensuring that the fibers in the solution are evenly distributed without forming local solution retention.

[0033] After keeping it for 2 hours, the temperature was lowered from 80°C to 70°C at a cooling rate of 1°C / min. During the cooling process, a stable temperature change rate must also be maintained to prevent the solution in the reaction system from cooling too quickly and causing the solute to recrystallize or precipitate. By slowly cooling, the molecular structure in the solution can be gradually stabilized, and the sudden change in temperature will not cause the reorganization of fibers or solutes. At the same time, the stirring speed of 700rpm can ensure the uniformity of the reaction system during the cooling stage and prevent the fibers in the solvent from agglomerating or precipitating during the cooling process.

[0034] Please continue reading Figure 1 , filtering and separating the undissolved polyester fibers, and washing and drying the separated polyester fibers; In one embodiment of the present invention, the filtering and separating out the undissolved polyester fibers, and washing and drying the separated polyester fibers, include: using a three-stage series filter to separate the solid and liquid from the reaction mixture, wherein the pore sizes of the three-stage series filter are 50 μm, 30 μm and 10 μm, respectively; performing multi-stage gradient ultrasonic cleaning on the separated polyester fibers, specifically including: first, washing with deionized water at a frequency of 40 kHz for 20 minutes, then washing with ethanol at a frequency of 60 kHz for 15 minutes, and finally washing with ethanol at a frequency of 80 kHz for 15 minutes. The fiber was cleaned with acetone for 10 minutes at a high frequency, and the cleaning solution was removed by centrifugation between each cleaning stage; the cleaned polyester fiber was precooled at -40°C for 2 hours; freeze-dried at a vacuum degree of 0.01 mbar, firstly heated from -40°C to 0°C at a heating rate of 1°C / min and maintained for 6 hours, then heated to room temperature at a heating rate of 0.5°C / min and maintained for 18 hours; pulse vacuum drying was performed at 40°C for 2 hours, with a pulse period of 2 minutes to evacuate to 0.1 mbar, and 1 minute to pass dry nitrogen to normal pressure.

[0035] Specifically, the three-stage series filter is a device that connects multiple filters with different pore sizes. The filters with different pore sizes are arranged at intervals in the direction of liquid flow, and the filter pore sizes are 50μm, 30μm and 10μm respectively. This graded filtration method can effectively intercept particles of different sizes by gradually reducing the pore size. For example, the initial 50μm filter is used to remove larger impurities or undissolved solids, followed by a 30μm filter to further filter smaller particles, and finally a 10μm filter to ensure that the finest solid matter is intercepted. This design avoids the risk of clogging of a single filter and ensures that fibers and impurities can be gradually separated, greatly improving the efficiency and stability of filtration.

[0036] After solid-liquid separation, the separated polyester fiber needs to be cleaned by multi-stage gradient ultrasonic cleaning. Ultrasonic cleaning is a process that uses high-frequency sound waves to form tiny bubbles in the liquid. The impact force generated when these bubbles burst quickly can effectively remove dirt and residual chemicals on the fiber surface. First, use deionized water at a frequency of 40kHz to clean for 20 minutes. The purpose of this step is to remove the initial dirt and water-soluble substances on the fiber surface. Deionized water will not pollute the fiber and ensure the cleanliness of the cleaning. Subsequently, use ultrasonic waves at a frequency of 60kHz and ethanol solution for 15 minutes. As an organic solvent, ethanol can remove residual organic matter on the fiber surface, and due to its rapid evaporation characteristics, it is conducive to the subsequent drying process. Finally, use ultrasonic waves at a frequency of 80kHz and acetone for 10 minutes. Acetone is a strong organic solvent that can further remove those organic residues that are difficult to dissolve. These three cleaning steps are performed in sequence to ensure that all kinds of dirt and chemical residues on the fiber surface can be thoroughly removed. After each ultrasonic cleaning, the cleaning liquid is removed by centrifugal separation, and the fiber and cleaning solution are separated by high-speed rotation to ensure that the cleaned fiber is completely free of liquid residue.

[0037] After washing, the polyester fiber is placed in a pre-cooling treatment at -40℃ for 2 hours. The purpose of this step is to prepare for the subsequent freeze drying. Through the pre-cooling treatment, the water in the fiber can be quickly frozen to form ice crystals, ensuring that the water can be directly sublimated during the freeze drying process, avoiding the influence of water on the fiber structure when it exists in liquid state. Next, the fiber enters the freeze drying equipment, and the vacuum degree is maintained at an extremely low pressure of 0.01mbar. Freeze drying is a process that directly sublimates solid water (ice) into gas under low temperature vacuum to avoid the damage of water to the material in liquid state. The freeze drying process first increases the temperature from -40℃ to 0℃ at a heating rate of 1℃ / min and maintains it for 6 hours. This slow heating rate ensures that the ice crystals can sublimate evenly and stably, avoiding fiber shrinkage or deformation caused by too fast heating. Subsequently, it is heated to room temperature at a heating rate of 0.5℃ / min and maintained for 18 hours to ensure that the remaining water is completely sublimated and the fiber reaches the best state after drying.

[0038] Finally, in order to further ensure the thoroughness of drying of the polyester fiber, pulse vacuum drying was carried out at 40°C for 2 hours. Pulse vacuum drying is to further remove moisture by periodically changing the vacuum degree. The specific operation is to evacuate to 0.1mbar every 2 minutes, and then introduce dry nitrogen to normal pressure for 1 minute. In this way, trace moisture on the fiber surface can be gradually removed, while also avoiding the stress on the fiber surface that may be caused by continuous vacuum. The pulse operation ensures the gentleness of the drying process, preventing the fiber from cracking or deforming due to over-drying, and by adding dry nitrogen, the removal of volatile residues can be accelerated.

[0039] Please continue reading Figure 1 , contacting the dried polyester fiber with an organic solvent mixture, wherein the organic solvent mixture comprises a halogenated alkane, a fluorine-containing organic acid and a lactone compound; In one embodiment of the present invention, the polyester fiber after the drying treatment is contacted with an organic solvent mixture, wherein the organic solvent mixture contains halogenated alkanes, fluorinated organic acids and lactone compounds, comprising: preparing an organic solvent mixture, comprising: selecting dichloromethane as the halogenated alkanes, trifluoroacetic acid as the fluorinated organic acid, and γ-butyrolactone as the lactone compound, and mixing them in a volume ratio of 3:6:1; mixing the polyester fiber after the drying treatment with the prepared organic solvent mixture in a mass ratio of 1:20; first dissolving at 60°C for 2 hours under nitrogen protection, and then continuing to dissolve at 80°C for 4 hours; during the dissolution process, intermittently ultrasonicating the reaction mixture for 1 minute every 30 minutes, and the power of the ultrasonic treatment is 200 W and the frequency is 40 kHz.

[0040] Specifically, dichloromethane, as a non-polar solvent, can effectively dissolve polyester molecules, especially its good solubility for polymer materials. In addition, trifluoroacetic acid, as a fluorine-containing organic acid, can further enhance the polarity of the solvent and help break the hydrogen bond structure in the polyester fiber, thereby promoting dissolution. γ-butyrolactone is a compound commonly used to enhance solvent stability and reaction efficiency. As an auxiliary component, it can not only ensure the uniformity of the solution, but also help maintain the dissolution speed and uniformity of the fiber.

[0041] The dried polyester fiber and the solvent mixture are mixed at a mass ratio of 1:20 to ensure that the solvent fully covers the fiber surface and undergoes a uniform dissolution reaction with it. If the solvent ratio is too small, the contact area between the fiber and the solvent is insufficient and the fiber cannot be completely dissolved; conversely, if the solvent ratio is too large, it will cause a waste of resources. The ratio of 1:20 can effectively dissolve the fiber and ensure the rational use of resources.

[0042] Dissolution under nitrogen protection is to avoid possible oxidation or moisture absorption caused by exposure of dichloromethane and trifluoroacetic acid to the air, and to maintain the purity and stability of the solvent system. The nitrogen environment not only prevents the solvent from reacting with moisture or oxygen in the air, but also ensures that the solvent does not evaporate too quickly during the dissolution process, thereby maintaining the continuity and efficiency of the reaction.

[0043] The dissolution process is divided into two stages. First, it is dissolved at 60°C for 2 hours. The temperature setting of 60°C is based on the dissolution characteristics of polyester fibers. At this temperature, the solvent can quickly penetrate the fiber structure and begin to dissolve the surface layer. At this time, the polyester molecular chains gradually untie, but will not be subjected to excessive thermal stress, so the basic physical properties of the material can be maintained. The purpose of this stage is to start the dissolution of the fiber slowly and evenly.

[0044] Next, the temperature is raised to 80°C and maintained for 4 hours. 80°C is the optimal temperature for the dissolution of polyester fibers. At this temperature, the intermolecular forces between the solvent and the fiber are greatly enhanced, and the molecular chains inside the fiber will gradually unfold and dissolve into the solution. This process lasts for 4 hours, which is enough to ensure that the fiber is completely dissolved and prevent the appearance of incompletely reacted residues during the dissolution process.

[0045] In addition, intermittent ultrasonic treatment is introduced to further promote dissolution. Ultrasonic treatment is performed for 1 minute every 30 minutes, with a power of 200W and a frequency of 40kHz. Ultrasonic treatment produces local high pressure and microbubble rupture effects through cavitation effect, which can effectively destroy the undissolved and insoluble parts of polyester fibers and accelerate the disintegration of fibers. The intermittent setting is to provide continuous dissolution driving force without damaging the fibers.

[0046] Please continue reading Figure 1 , under the protection of inert gas, the dissolved mixture is subjected to multi-stage membrane filtration, and the filtered solution is concentrated; In one embodiment of the present invention, the dissolved mixture is subjected to multi-stage membrane filtration under the protection of an inert gas, and the filtered solution is concentrated, including: under the protection of an inert gas, the dissolved mixture is filtered through filter membranes with pore sizes of 10 μm, 1 μm and 0.1 μm in sequence; during the filtration process, a vibration of 100-500 kHz is applied to the filter membrane; within a temperature range of -5°C to 5°C, the filtered solution is concentrated at a pressure of 0.1-1 mbar, and the volatile solvent is condensed and recovered.

[0047] Specifically, inert gas protection (such as nitrogen) is selected to prevent the active ingredients in the solution from reacting with oxygen or moisture in the air during the filtration process, maintaining the stability and purity of the solution. The purpose of this step is to ensure that the insoluble impurities in the solution can be filtered out step by step. The 10μm primary filter membrane is used to remove larger particles and fiber fragments, while the subsequent 1μm and 0.1μm filter membranes successively remove finer particles and impurities, ensuring that only evenly distributed dissolved components remain in the solution.

[0048] During the filtration process, applying 100-500kHz vibration helps prevent clogging of the filter membrane and ensure the continuity and efficiency of filtration. Vibration acts on the filter membrane through a small mechanical amplitude, which can reduce the accumulation of particles in the solution on the membrane surface and prevent particles from blocking the micropores, thereby increasing the filtration speed and extending the service life of the filter membrane. The vibration frequency range is set between 100-500kHz to ensure that sufficient cleaning effect can be maintained on filter membranes of different sizes and avoid excessive damage to the membrane structure.

[0049] Next, the filtered solution is concentrated. The concentration process is carried out in a temperature range of -5°C to 5°C to prevent excessive evaporation of volatile components in the solution and maintain the stability of the reaction liquid. In a low temperature environment, the solvent evaporation rate is reduced, which can better control the concentration effect in the solution and reduce the decomposition or denaturation of the solute due to increased temperature. In addition, applying a low pressure of 0.1-1mbar during the concentration process can effectively increase the evaporation rate of the solvent while avoiding overheating of the solution.

[0050] At the same time, in order to minimize the waste of solvents and environmental impact, the volatilized solvents are condensed and recovered during the concentration process. After the solvent evaporates, it can be effectively converted back into liquid through the condensation system for reuse. This not only improves the utilization efficiency of the solvent and reduces operating costs, but also reduces the pollution of the solvent's volatilization emissions to the environment.

[0051] Please continue reading Figure 1 , dividing the concentrated solution into two parts, adding at least one functional monomer and a photoinitiator into one part to obtain a functionalized spinning solution, and using the other part as a basic spinning solution; In one embodiment of the present invention, the concentrated solution is divided into two parts, one part of which is added with at least one functional monomer and a photoinitiator to obtain a functionalized spinning solution, and the other part is used as a basic spinning solution, including: dividing the concentrated solution into two parts; adding a functional monomer mixture with a mass fraction of 1-5% to one part of the solution, wherein the functional monomer mixture includes a hydrophobic monomer, a hydrophilic monomer and an antibacterial monomer; adding 0.1-1% of photosensitive nanoparticles as a photoinitiator to the solution to which the functional monomer is added; stirring the solution to which the functional monomer and the photoinitiator are added at a speed of 300-500 rpm for 30-60 minutes under light-proof conditions to obtain a functionalized spinning solution; and concentrating the other part of the solution to which the functional monomer is not added under reduced pressure at 60-80°C for 10-30 minutes to obtain a basic spinning solution.

[0052] Specifically, the composition of the functional monomer mixture includes hydrophobic monomers, hydrophilic monomers and antibacterial monomers. This formula design is to give the final fiber material multifunctionality. Hydrophobic monomers can make the fiber material have good water resistance and are suitable for special environmental conditions or application scenarios; hydrophilic monomers improve the hygroscopicity and affinity of the material with water; the addition of antibacterial monomers can make the material have antibacterial functions, especially in the medical, sanitary and textile fields. This property can extend the service life of the material and improve its safety. Through the reasonable ratio of these three types of monomers, the final spinning solution prepared can have multiple functions at the same time to meet the needs of different fields.

[0053] After the functional monomer is added to the solution, 0.1-1% of photosensitive nanoparticles need to be added as photoinitiators. Photoinitiators can initiate polymerization reactions under light, and their introduction can control the timing and rate of polymerization, especially in light-controlled reactions. This process can accurately adjust the morphology and structure of the material. The use of photosensitive nanoparticles can not only improve the efficiency of the reaction, but also ensure that the polymerization reaction is completed under lower energy light conditions, thereby reducing energy consumption. In addition, the nanoparticles are small in size and can be evenly dispersed in the solution, which will not affect the viscosity of the solution and the smooth progress of the spinning process.

[0054] Next, the solution with added functional monomers and photoinitiators is placed in a light-proof condition and stirred at a speed of 300-500rpm for 30-60 minutes. The main purpose of this step is to ensure that the functional monomers, photoinitiators and basic solution are fully mixed. The light-proof condition is to prevent the photoinitiator from starting the polymerization reaction prematurely during the stirring process, and to ensure that the entire system can only start polymerization after it is evenly dispersed. The stirring speed is set between 300-500rpm, which can not only provide sufficient shear force to ensure the uniformity of the solution, but also avoid excessive stirring rate causing nanoparticle agglomeration or solution foaming, affecting the stability of spinning. The choice of stirring time ensures that all components can be completely dissolved and form a stable functionalized spinning solution.

[0055] For the other part of the solution without adding functional monomers, it is concentrated under reduced pressure at 60-80°C for 10-30 minutes to obtain a basic spinning solution. The purpose of reduced pressure concentration is to further remove the solvent so that the solution reaches a viscosity suitable for spinning. The temperature range of 60-80°C ensures that the solvent can evaporate quickly under low pressure conditions without causing thermal degradation of the solute or changes in the properties of the solution. By adjusting the temperature and pressure conditions, the viscosity of the solution can be precisely controlled to ensure good fluidity and film-forming properties in the subsequent spinning process. The reduced pressure concentration time is adjusted according to the initial concentration and target viscosity of the solution to ensure that the concentration is completed within 10-30 minutes so that the solution has stable spinning performance.

[0056] Please continue reading Figure 1 , the functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV, an electric field gradient is formed between the solution delivery area and the fiber collection area, the electric field distribution is adjusted to control the deposition of the fibers in the collection area, and a nanofiber membrane is formed in the collection area.

[0057] In one embodiment of the present invention, the functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV, an electric field gradient is formed between the solution delivery area and the fiber collection area, the electric field distribution is adjusted to control the deposition of the fibers in the collection area, and a nanofiber membrane is formed in the collection area, including: separately delivering the functionalized spinning solution and the basic spinning solution through a coaxial nozzle, wherein the functionalized spinning solution is delivered through an inner nozzle, and the basic spinning solution is delivered through an outer nozzle; a multi-pole electric field is set between the nozzle and the collector, and a non-uniform electric field distribution is generated within a range of 10-30 kV by adjusting the voltage of each pole; a conductive pattern is set on the surface of the collector, and the conductivity of the conductive pattern is within a range of arrive The electric field strength is adjustable within the range of S / m; during the fiber deposition process, a low-frequency vibration of 50-200 Hz is applied to the collector; during the nanofiber membrane formation process, the electric field strength and distribution are gradually changed through program control, and the range of the electric field strength change is 1-3 kV increase or decrease every 5 minutes.

[0058] Specifically, in this scheme, the functionalized spinning solution and the basic spinning solution are first delivered separately through the coaxial nozzle. The design of the coaxial nozzle allows the functionalized spinning solution to be delivered through the inner nozzle and the basic spinning solution to be delivered through the outer nozzle. The key to this design is that the two solutions will not merge during the spraying process, because the strong electric field during electrospinning causes the solution to be instantly stretched into fibers. This extremely fast stretching speed allows the solution to be stretched into an independent fiber structure before it diffuses or mixes. Finally, a fiber with a "core-shell" structure is formed. The functionalized solution serves as the core of the fiber, while the basic solution is coated on the outer layer to form a multi-layer composite fiber. The functionalized solution in the inner layer gives the fiber specific functionality, such as antibacterial, hydrophilic or hydrophobic, while the outer layer provides strength and physical protection to ensure the durability and performance of the fiber in the application.

[0059] Electrospinning relies on an electric field to stretch a solution to form fibers. Here we need to explain why the electric field can stretch the solution: when an electric field is applied between the nozzle and the collector, the ejected solution is charged, and the electrostatic force applied by the electric field overcomes the surface tension of the solution, causing it to be quickly stretched from the nozzle into fibers. The electric field breaks the cohesion of the solution molecules to form a filament structure by providing a strong electrostatic force. The strength of the electric field directly affects the stretching speed and diameter of the fiber. Higher electric field strengths provide greater stretching forces and generate thinner fibers, while lower electric fields are suitable for generating thicker fiber structures. In addition, the setting of a non-uniform electric field ensures that the fibers are uniformly stressed during the stretching process, preventing the fibers from being entangled or unevenly deposited, and ensuring the quality and consistency of the fiber membrane.

[0060] In this process, a conductive pattern is set on the collector surface, and the conductivity of the conductive pattern is adjustable. By adjusting the local conductivity, the electric field distribution on the collector surface is affected, so that the deposition position and density of the fibers can be precisely controlled. By adjusting the conductivity, the intensity of the electric field can be guided in different areas of the collector surface, so that denser fiber deposition is formed in the required area, while other areas form sparser fiber deposition. Through this precise control, the thickness and morphology of the fiber membrane can be adjusted according to different application requirements.

[0061] During the fiber deposition process, low-frequency vibration of 50-200Hz is applied to the collector to further optimize the fiber arrangement and deposition effect. Low-frequency vibration can eliminate fiber accumulation caused by electrostatic adsorption, promote the uniform diffusion of fibers on the collector surface, and form a smooth and consistent deposition layer. The vibration frequency is designed not to damage the fiber structure, but to promote the orderly arrangement of fibers on the collector surface, forming a denser and more uniform fiber film.

[0062] During the nanofiber membrane formation process, the electric field strength is programmed and dynamically adjusted by 1-3kV every 5 minutes to meet the fiber stretching and deposition requirements at different stages. This dynamic adjustment is to meet the needs of different fiber formation stages. When the fibers are initially stretched from the nozzle, the higher electric field strength can provide sufficient stretching force to quickly form fine fibers from the solution. When the fibers are gradually deposited, appropriately reducing the electric field strength can make the fibers deposit more evenly, avoiding excessive stretching of the fibers leading to breakage or uneven deposition. By programmatically controlling the gradual adjustment of the electric field strength, it is ensured that the fibers are subjected to appropriate stretching forces during the forming and deposition stages, thereby forming a uniform and dense fiber membrane and improving its mechanical properties and structural consistency.

[0063] In one embodiment of the present invention, after forming a nanofiber membrane in the collection area, the following steps include: placing the nanofiber membrane in an environment filled with inert gas and irradiating it with ultraviolet light of a wavelength of 280-320nm for 10-30 minutes; heat-treating the cross-linked nanofiber membrane at 50-70°C for 2-4 hours; immersing the heat-treated nanofiber membrane in a nano titanium dioxide solution with a mass fraction of 0.5-2% for 1-3 hours, and then drying it at 80-100°C for 30-60 minutes.

[0064] Specifically, in this scheme, after the nanofiber membrane is formed, it needs to be further processed to enhance its function and structural stability. First, the nanofiber membrane is placed in an environment filled with an inert gas (such as nitrogen or argon) and irradiated with ultraviolet light at a wavelength of 280-320nm for 10-30 minutes. This step triggers a photocrosslinking reaction through ultraviolet light irradiation, so that the molecular chains inside the fiber form a more stable three-dimensional network structure, enhancing the mechanical strength and chemical resistance of the nanofiber membrane. The inert gas environment is selected to avoid oxygen interfering with the crosslinking reaction and prevent oxidation of the membrane surface, thereby maintaining chemical stability. The irradiation time of 10-30 minutes is to ensure that the crosslinking reaction is fully carried out without excessively damaging the structure of the membrane.

[0065] After the UV irradiation, the fiber membrane is then heat treated at 50-70°C for 2-4 hours. The purpose of the heat treatment is to further stabilize the cross-linked structure, eliminate residual stress in the material, and improve the crystallinity and mechanical properties of the fiber membrane by rearrangement of the molecular chains. This temperature range can avoid damage to the membrane structure by high temperature, while effectively improving the strength and flexibility of the material. Next, the heat-treated nanofiber membrane will be immersed in a nano-titanium dioxide solution with a mass fraction of 0.5-2% for 1-3 hours. Nano-titanium dioxide gives the fiber membrane additional functions such as photocatalytic, antibacterial and self-cleaning properties. By dipping in a solution at this concentration, a uniform coating of titanium dioxide particles can be formed on the membrane surface, ensuring uniform distribution of functionality. The immersion time is controlled to 1-3 hours to ensure sufficient particle attachment without affecting the pore structure of the fiber membrane.

[0066] After impregnation, the fiber membrane is dried at 80-100°C for 30-60 minutes to remove moisture from the solution and solidify the titanium dioxide coating. The drying temperature is set at 80-100°C, which can accelerate the evaporation of water while avoiding damage to the structure of the fiber membrane due to excessive temperature. The drying time of 30-60 minutes ensures uniform curing of the coating and complete volatilization of water, so that the titanium dioxide particles are firmly attached to the surface of the membrane. After these processing steps, the nanofiber membrane not only has excellent mechanical strength, but also has functions such as photocatalysis and antibacterial, ensuring excellent performance in a variety of application scenarios.

[0067] It should also be noted that in the present application, the natural deep eutectic solvent (NADES) can be recycled and reused. Due to its good stability and low volatility, NADES will not undergo chemical decomposition or significant loss during the treatment of textile waste. After the treatment, the solvent can be separated from the reaction system by low-temperature evaporation or reduced pressure distillation, and then purified and concentrated to restore its original properties. In this way, the recovered NADES can be used again in a new textile waste treatment cycle, ensuring the sustainability and economy of the process, and greatly reducing solvent waste and environmental impact.

[0068] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for recycling polyester textile waste, characterized in that: include: contacting the textile waste with a natural deep eutectic solvent, the natural deep eutectic solvent comprising a hydrogen bond acceptor and at least two hydrogen bond donors, and stirring at a predetermined temperature for a predetermined time; filtering and separating the undissolved polyester fibers, and washing and drying the separated polyester fibers; contacting the dried polyester fiber with an organic solvent mixture comprising a halogenated alkane, a fluorine-containing organic acid and a lactone compound; Under the protection of inert gas, the dissolved mixture is subjected to multi-stage membrane filtration, and the filtered solution is concentrated; The concentrated solution is divided into two parts, one part is added with at least one functional monomer and a photoinitiator to obtain a functionalized spinning solution, and the other part is used as a basic spinning solution; The functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV to form an electric field gradient between the solution delivery area and the fiber collection area. The electric field distribution is adjusted to control the deposition of the fibers in the collection area to form a nanofiber membrane in the collection area.

2. The method for recycling polyester textile waste according to claim 1, characterized in that: The step of contacting the textile waste with a natural deep eutectic solvent, wherein the natural deep eutectic solvent comprises a hydrogen bond acceptor and at least two hydrogen bond donors, and stirring at a preset temperature for a predetermined time comprises: Cut the textile waste into small pieces of 1-5 cm² and dry them in vacuum at 50°C for 6 hours; A natural deep eutectic solvent is prepared, the preparation steps comprising: selecting choline chloride as a hydrogen bond acceptor, selecting lactic acid and urea as hydrogen bond donors, mixing them in a molar ratio of 1:2:0.5, adding 1wt% of cerium oxide nanocatalyst, and heating the mixture from room temperature to 80°C at a heating rate of 2°C / min under nitrogen protection, and stirring for 2 hours to form a transparent liquid; Mixing the dried textile waste pieces with the prepared natural deep eutectic solvent in a mass ratio of 1:10; The mixture is placed in a temperature-controlled reactor and stirred at a preset temperature for a predetermined time.

3. The method for recycling polyester textile waste according to claim 2, characterized in that: The stirring at a preset temperature for a predetermined time comprises: The temperature was raised from room temperature to 60 °C at a heating rate of 2 °C / min and maintained at a stirring speed of 600 rpm for 1 h; Continue to increase the temperature to 80°C at a rate of 1°C / min and maintain at a stirring speed of 800 rpm for 2 hours; Finally, the temperature was lowered to 70°C at a rate of 1°C / min and maintained at a stirring speed of 700 rpm for 1 hour.

4. The method for recycling polyester textile waste according to claim 1, characterized in that: The filtering and separating out the undissolved polyester fibers, and washing and drying the separated polyester fibers, comprises: The reaction mixture is subjected to solid-liquid separation using a three-stage series filter, wherein the pore sizes of the three-stage series filter are 50 μm, 30 μm and 10 μm, respectively; The separated polyester fibers were subjected to multi-stage gradient ultrasonic cleaning, specifically comprising: firstly, cleaning with deionized water at a frequency of 40kHz for 20 minutes, then cleaning with ethanol at a frequency of 60kHz for 15 minutes, and finally cleaning with acetone at a frequency of 80kHz for 10 minutes, and the cleaning liquid was removed by centrifugal separation between each stage of cleaning; The cleaned polyester fiber was precooled at -40°C for 2 hours; Freeze drying was performed under a vacuum of 0.01 mbar, first at a heating rate of 1°C / min from -40°C to 0°C and maintained for 6 hours, then at a heating rate of 0.5°C / min to room temperature and maintained for 18 hours; Pulse vacuum drying was performed at 40°C for 2 hours, with a pulse cycle of evacuating to 0.1 mbar for 2 minutes and passing dry nitrogen to normal pressure for 1 minute.

5. The method for recycling polyester textile waste according to claim 1, characterized in that: The step of contacting the dried polyester fiber with an organic solvent mixture, wherein the organic solvent mixture comprises halogenated alkanes, fluorine-containing organic acids and lactone compounds, including: preparing an organic solvent mixture, comprising: selecting dichloromethane as a halogenated alkane, trifluoroacetic acid as a fluorine-containing organic acid, and γ-butyrolactone as a lactone compound, and mixing them in a volume ratio of 3:6:1; The dried polyester fiber is mixed with the prepared organic solvent mixture at a mass ratio of 1:20; Under nitrogen protection, first dissolve at 60°C for 2 hours, and then continue to dissolve at 80°C for 4 hours; During the dissolution process, the reaction mixture was intermittently sonicated for 1 min every 30 min at a power of 200 W and a frequency of 40 kHz.

6. The method for recycling polyester textile waste according to claim 1, characterized in that: The method of filtering the dissolved mixture through multi-stage membranes under the protection of an inert gas and concentrating the filtered solution comprises: Under the protection of inert gas, the dissolved mixture is filtered through filter membranes with pore sizes of 10 μm, 1 μm and 0.1 μm in sequence; During the filtration process, vibrations of 100-500kHz are applied to the filter membrane; The filtered solution is concentrated at a temperature range of -5°C to 5°C and a pressure of 0.1-1 mbar, and the volatilized solvent is condensed and recovered.

7. The method for recycling polyester textile waste according to claim 1, characterized in that: The concentrated solution is divided into two parts, one part of which is added with at least one functional monomer and a photoinitiator to obtain a functionalized spinning solution, and the other part is used as a basic spinning solution, comprising: The concentrated solution is divided into two equal parts; Adding 1-5% by weight of a functional monomer mixture to a portion of the solution, wherein the functional monomer mixture includes a hydrophobic monomer, a hydrophilic monomer and an antibacterial monomer; Adding 0.1-1% of photosensitive nanoparticles as a photoinitiator to the solution to which the functional monomer is added; Stirring the solution to which the functional monomer and the photoinitiator are added at a speed of 300-500 rpm for 30-60 minutes under light-proof conditions to obtain a functionalized spinning solution; Another part of the solution without adding the functional monomer is concentrated under reduced pressure at 60-80° C. for 10-30 minutes to obtain a basic spinning solution.

8. The method for recycling polyester textile waste according to claim 1, characterized in that: The functionalized spinning solution and the basic spinning solution are simultaneously delivered to an electrostatic field with a voltage of 10-30 kV, an electric field gradient is formed between the solution delivery area and the fiber collection area, and the electric field distribution is adjusted to control the deposition of the fibers in the collection area to form a nanofiber membrane in the collection area, including: The functionalized spinning solution and the basic spinning solution are respectively delivered through the coaxial nozzles, wherein the functionalized spinning solution is delivered through the inner nozzle and the basic spinning solution is delivered through the outer nozzle; A multi-pole electric field is set between the nozzle and the collector, and a non-uniform electric field distribution is generated by adjusting the voltage of each pole within the range of 10-30kV; A conductive pattern is provided on the surface of the collector, and the conductivity of the conductive pattern is arrive Adjustable within S / m range; During the fiber deposition process, a low-frequency vibration of 50-200 Hz is applied to the collector; During the formation of the nanofiber membrane, the electric field strength and distribution are gradually changed through program control, and the range of change of the electric field strength is an increase or decrease of 1-3 kV every 5 minutes.

9. The method for recycling polyester textile waste according to claim 1, characterized in that: After forming the nanofiber membrane in the collection area, the method comprises: The nanofiber membrane is placed in an environment filled with inert gas and irradiated with ultraviolet light of 280-320 nm wavelength for 10-30 minutes; heat treating the cross-linked nanofiber membrane at 50-70° C. for 2-4 hours; The heat-treated nanofiber membrane is immersed in a nano-titanium dioxide solution with a mass fraction of 0.5-2% for 1-3 hours, and then dried at 80-100° C. for 30-60 minutes.

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