Method for preparing smoke dust filtering material by recycling waste aramid fiber fabric

Abstract

The invention discloses a method for preparing a smoke dust filtering material by recycling waste aramid fiber fabric, and relates to the technical field of high polymer materials. When the smoke dust filtering material is prepared, waste aramid fiber fabric is cut, washed and dried, and then reacts with 3-chloropropyl isocyanate and dibutyl (allyl) phosphine in sequence to prepare modified aramid fiber; the preparation method comprises the following steps: enabling graphene oxide powder to react with 3-aminopropyltrimethoxysilane to prepare pre-modified graphene oxide, and then enabling the pre-modified graphene oxide to react with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane to prepare modified graphene oxide; the modified aramid fibers and the modified graphene oxide are mixed and then subjected to electrostatic spinning, and an aramid nanofiber membrane is prepared; and immersing the aramid nanofiber membrane into a 2, 2-dimethoxy-2-phenyl acetophenone solution, and carrying out ultraviolet radiation, so as to obtain the smoke dust filtering material. The smoke dust filtering material prepared by the invention has good filtering performance, flame retardant property, antibacterial property, mechanical property and heavy metal ion adsorption performance.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, in particular to a method for preparing smoke filter materials by recycling waste aramid fabrics. Background Art

[0002] With the development of the aramid industry, the recycling of waste aramid fabrics has become a huge challenge that people cannot avoid. The recycling and reuse of aramid fabrics in a greener and more environmentally friendly way has become a topic of increasing concern and heated discussion.

[0003] With the development and advancement of science and technology, research on high-temperature filter materials has attracted widespread attention from scholars both domestically and internationally. High-temperature filter materials have a wide range of applications, primarily in the automotive, pharmaceutical, environmental, nuclear, and military sectors. High-temperature dust filtration requires filter media with excellent heat and chemical resistance. Aramid, with its high strength, high modulus, high-temperature resistance, and high filtration efficiency, is widely used in this field.

[0004] Industrial smoke emissions from industries such as iron and steel, cement kilns, thermal power plants, waste incineration, and the chemical industry are the primary cause of current air pollution. Eliminating air pollution at the source and controlling high-temperature industrial smoke emissions are of great significance to environmental protection. Therefore, the present invention has prepared a smoke filter material with excellent filtration, flame retardancy, antibacterial, mechanical, and heavy metal ion adsorption properties. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for recycling waste aramid fabrics to prepare smoke filter materials, so as to solve the problems existing in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: A method for preparing a smoke filter material by recycling waste aramid fabrics. The smoke filter material is prepared by immersing an aramid nanofiber membrane in a 2,2-dimethoxy-2-phenylacetophenone solution and subjecting it to ultraviolet irradiation.

[0007] As an optimization, the aramid nanofiber membrane is prepared by electrostatic spinning after mixing modified aramid fiber and modified graphene oxide.

[0008] As an optimization, the modified aramid fiber is prepared by cutting, washing, and drying waste aramid fabrics, and then reacting them with 3-chloropropyl isocyanate and dibutyl (allyl) phosphine in sequence.

[0009] As an optimization, the modified graphene oxide is prepared by reacting graphene oxide powder with 3-aminopropyltrimethoxysilane to obtain pre-modified graphene oxide, and then reacting with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane to obtain the pre-modified graphene oxide.

[0010] A method for recycling waste aramid fabrics to prepare smoke filter materials, comprising the following preparation steps: (1) Cutting, washing and drying waste aramid fabrics to obtain waste aramid fabric recycling materials; mixing the waste aramid fabric recycling materials, 3-chloropropyl isocyanate and dibutyltin dilaurate in a nitrogen atmosphere, washing and drying after taking out to obtain pre-modified aramid fiber; mixing the pre-modified aramid fiber, dibutyl (allyl) phosphine and N,N-dimethylacetamide in a nitrogen atmosphere, performing reduced pressure distillation, washing and drying to obtain modified aramid fiber; (2) Graphene oxide powder, N,N'-dicyclohexylcarboximide, and tetrahydrofuran were mixed evenly, ultrasonically dispersed, 3-aminopropyltrimethoxysilane was added and stirred for reaction, filtered, washed, and dried to obtain pre-modified graphene oxide; pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, and N,N-dimethylformamide were mixed evenly, deionized water was added dropwise at a uniform rate, stirred for reaction, residual water was removed with anhydrous calcium chloride, centrifuged, washed, and dried to obtain modified graphene oxide; (3) The modified aramid fiber, lithium chloride, and N,N-dimethylacetamide were mixed evenly, stirred to dissolve, and modified graphene oxide was added, and ultrasonic dispersion was performed to obtain a spinning solution; the spinning solution was added to a syringe and electrospun to obtain an aramid nanofiber membrane; the aramid nanofiber membrane was immersed in a 2,2-dimethoxy-2-phenylacetophenone solution, and irradiated with ultraviolet light with a wavelength of 365 nm to react, and then taken out, washed, and dried to obtain a smoke filter material.

[0011] As an optimization, the modified aramid fiber described in step (1) includes the following preparation steps: cutting the waste aramid fabric into 1.5 cm × 1.5 cm strips, placing them in anhydrous ethanol for ultrasonic cleaning for 20 to 40 minutes, taking them out and washing them with deionized water for 2 to 4 times, and vacuum drying them at 60 to 70 ° C for 6 to 8 hours to obtain the waste aramid fabric recycling material; in a nitrogen atmosphere, the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate are mixed uniformly in a mass ratio of 1: (30 to 50): (0.002 to 0.004), and reacting them at room temperature for 10 to 12h, take it out and wash it with acetone 2~4 times, and vacuum dry it at 20~30℃ for 10~12h to obtain pre-modified aramid fiber; under nitrogen atmosphere, the pre-modified aramid fiber, dibutyl (allyl) phosphine, and N,N-dimethylacetamide are evenly mixed in a mass ratio of 1: (0.6~0.8): (30~50), stirred at 80~90℃ and 200~300r / min for 70~72h, and N,N-dimethylacetamide is removed by reduced pressure distillation, washed with anhydrous ethanol 2~4 times, and vacuum dried at 40~50℃ for 10~12h to obtain modified aramid fiber.

[0012] As an optimization, the modified graphene oxide described in step (2) includes the following preparation steps: graphene oxide powder, N,N'-dicyclohexylcarboximide, and tetrahydrofuran are mixed uniformly in a mass ratio of 1: (0.06~0.08): (15~20), ultrasonically dispersed for 20~40min, 3-aminopropyltrimethoxysilane in an amount of 1~1.5 times the mass of graphene oxide is added, stirred at 20~30℃ and 200~300r / min for 4~6h, filtered and washed with anhydrous ethanol 4~6 times, and vacuum dried at 50~60℃ for 10~12h to obtain pre-modified graphene oxide; pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, N,N-dimethylformamide are mixed uniformly in a mass ratio of 1: (0.06~0.08): (15~20), ultrasonically dispersed for 20~40min, 3-aminopropyltrimethoxysilane in an amount of 1~1.5 times the mass of graphene oxide is added, stirred at 200~300r / min for 4~6h, filtered and washed with anhydrous ethanol 4~6 times, and vacuum dried at 50~60℃ for 10~12h to obtain pre-modified graphene oxide. (0.7~0.8): (0.6~0.7): (0.004~0.006): (40~50) were mixed evenly, ultrasonically dispersed for 20~40 minutes, stirred at 60~70°C and 200~300 r / min for 40~60 minutes, and deionized water (0.18~0.22 times the mass of the pre-modified graphene oxide) was uniformly added at a dropping rate of 3 ml / min. The mixture was stirred at 60~70°C and 200~300 r / min for 4~5 hours, cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 8000~10000 rpm for 10~12 minutes. The obtained precipitate was washed with anhydrous ethanol 2~4 times and vacuum dried at 40~50°C for 10~12 hours to obtain modified graphene oxide.

[0013] As an optimization, the smoke filter material described in step (3) includes the following preparation steps: uniformly mixing modified aramid fiber, lithium chloride, and N,N-dimethylacetamide in a mass ratio of 1: (0.2~0.5): (8~9), stirring and dissolving at 80~90℃ and 200~300r / min for 10~12h, cooling to room temperature, adding 0.08~0.12 times of modified graphene oxide to the modified aramid fiber, ultrasonically dispersing for 20~40min to obtain a spinning solution; adding the spinning solution into a syringe, electrospinning for 10~12h to obtain an aramid nanofiber membrane; immersing the aramid nanofiber membrane in a 2,2-dimethoxy-2-phenylacetophenone solution, using ultraviolet light with a wavelength of 365nm, irradiating the reaction for 0.5~1.5h, taking it out, washing it with deionized water 2~4 times, and vacuum drying it at 20~30℃ for 10~12h to obtain a smoke filter material.

[0014] As an optimization, the graphene oxide powder has a thickness of 1 nm and a single-layer sheet diameter of 0.5-10 μm, and was purchased from Shanghai Maoguo Nanotechnology Co., Ltd.

[0015] As an optimization, the electrospinning process parameters are: using silicone oil paper as the receiving material, the spinning voltage is 20~30kV, the receiving distance is 15~25cm, the liquid feeding speed is 0.1~0.2mL / h, the temperature is 20~30℃, and the humidity is 48%~52%.

[0016] As an optimization, the 2,2-dimethoxy-2-phenylacetophenone solution is prepared by mixing 2,2-dimethoxy-2-phenylacetophenone and acetone in a mass ratio of 1: (90~100).

[0017] As an optimization, the reaction process of the pre-modified aramid fiber in step (1) is as follows: .

[0018] As an optimization, the reaction process of the modified aramid fiber in step (1) is as follows: .

[0019] As an optimization, the reaction process of the pre-modified graphene oxide in step (2) is as follows: .

[0020] Compared with the prior art, the present invention has the following beneficial effects: When preparing the smoke filter material, the present invention comprises the following steps: cutting, washing, and drying waste aramid fabric, and then reacting the fabric with 3-chloropropyl isocyanate to obtain pre-modified aramid fiber; reacting the pre-modified aramid fiber with dibutyl (allyl) phosphine to obtain modified aramid fiber; reacting graphene oxide powder with 3-aminopropyltrimethoxysilane to obtain pre-modified graphene oxide; reacting the pre-modified graphene oxide with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane to obtain modified graphene oxide; mixing the modified aramid fiber and the modified graphene oxide, and then electrospinning the mixture to obtain an aramid nanofiber membrane; and immersing the aramid nanofiber membrane in a 2,2-dimethoxy-2-phenylacetophenone solution and irradiating the mixture with ultraviolet light to obtain the smoke filter material.

[0021] First, waste aramid fabric is cut, washed, and dried, and then reacted with 3-chloropropyl isocyanate to produce pre-modified aramid fiber; the isocyanate group on the 3-chloropropyl isocyanate can replace the hydrogen atoms on the amide bond on the aramid surface, introducing the chlorine element into the material; the pre-modified aramid fiber is reacted with dibutyl (allyl) phosphine to produce modified aramid fiber, introducing the phosphorus element into the material and improving the material's flame retardant properties; the chlorine element on the pre-modified aramid fiber reacts with dibutyl (allyl) phosphine to form a quaternary phosphonium salt with antibacterial properties, thereby improving the material's antibacterial properties. At the same time, double bonds are introduced into the material, which react with the thiol groups on the modified graphene oxide to form a cross-linked network structure, thereby improving the material's mechanical properties.

[0022] Secondly, the graphene oxide powder is reacted with 3-aminopropyltrimethoxysilane to prepare pre-modified graphene oxide. Graphene oxide has a large specific surface area and contains a large number of oxygen-containing groups on the surface. It can adsorb heavy metal ions through electrostatic and complexation, thereby improving the material's ability to adsorb heavy metal ions. During the combustion process, graphene oxide can promote the formation of a denser and more continuous carbon layer, play a physical barrier role, and thus improve the flame retardant properties of the material. Graphene oxide has good mechanical properties. Modification of graphene oxide with 3-aminopropyltrimethoxysilane improves the graphene oxide's mechanical properties. The dispersion of graphene oxide with aramid fiber enhances the mechanical properties of the material; at the same time, silicon is introduced into the material to further improve the flame retardant properties of the material; pre-modified graphene oxide is reacted with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane to prepare modified graphene oxide, and amino and thiol groups are introduced into the material. The amino groups can form complexes with heavy metal ions, thereby improving the material's ability to adsorb heavy metal ions; at the same time, the thiol groups on the modified graphene oxide can react with the double bonds on the modified aramid fiber to form a thiol-ene reaction, forming a cross-linked network structure, which further improves the mechanical properties of the material.

[0023] Finally, the modified aramid fiber and modified graphene oxide were mixed and electrospun to produce an aramid nanofiber membrane. Graphene oxide was doped into the modified aramid fiber to narrow the diameter distribution of the nanofibers and distribute them in small sizes, making the gas filtration path more tortuous and improving the retention of fine particles, thereby improving the filtration performance of the material; the aramid nanofiber membrane was immersed in a 2,2-dimethoxy-2-phenylacetophenone solution and irradiated with ultraviolet light to produce a smoke filter material. 2,2-dimethoxy-2-phenylacetophenone was used as a photoinitiator. Under the irradiation of ultraviolet light, the double bonds on the modified aramid fiber and the thiol groups on the modified graphene oxide underwent a thiol-ene reaction to form a cross-linked network structure, thereby improving the mechanical properties of the material. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0025] The 2,2-dimethoxy-2-phenylacetophenone solution described in all the following examples and comparative examples was prepared by mixing 2,2-dimethoxy-2-phenylacetophenone and acetone in a mass ratio of 1:100.

[0026] Example 1: A method for recycling waste aramid fabrics to prepare smoke filter materials, comprising the following preparation steps: (1) Cut the waste aramid fabric into 1.5 cm × 1.5 cm strips, place them in anhydrous ethanol for ultrasonic cleaning for 20 min, take them out and wash them twice with deionized water, and vacuum dry them at 60 ° C for 6 h to obtain the waste aramid fabric recycling material; in a nitrogen atmosphere, the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate were mixed in a mass ratio of 1:30:0.002, reacted at room temperature for 10 h, and taken out. The pre-modified aramid fiber was washed twice with acetone and vacuum dried at 20°C for 10 h to obtain the pre-modified aramid fiber. Under a nitrogen atmosphere, the pre-modified aramid fiber, dibutyl (allyl) phosphine, and N,N-dimethylacetamide were uniformly mixed in a mass ratio of 1:0.6:30, stirred at 80°C and 200 r / min for 70 h, and N,N-dimethylacetamide was removed by vacuum distillation. The fiber was washed twice with anhydrous ethanol and vacuum dried at 40°C for 10 h to obtain the modified aramid fiber. (2) Graphene oxide powder, N,N'-dicyclohexylcarboximide and tetrahydrofuran were mixed in a mass ratio of 1:0.06:15, ultrasonically dispersed for 20 minutes, and 3-aminopropyltrimethoxysilane (1 times the mass of graphene oxide powder) was added. The mixture was stirred at 20°C and 200 r / min for 4 hours. The mixture was filtered and washed with anhydrous ethanol 4 times. The mixture was vacuum dried at 50°C for 10 hours to obtain pre-modified graphene oxide. Pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide and N,N-dimethylformamide were mixed in a mass ratio of 1:0.06:15. The mixture was ultrasonically dispersed for 20 minutes. The mixture was stirred at 20°C and 200 r / min for 4 hours. The mixture was filtered and washed with anhydrous ethanol 4 times. The mixture was vacuum dried at 50°C for 10 hours to obtain pre-modified graphene oxide. The mixture was uniformly mixed in a mass ratio of 1:0.7:0.6:0.004:40, ultrasonically dispersed for 20 minutes, stirred at 60°C and 200 r / min for 40 minutes, and deionized water (0.18 times the mass of the pre-modified graphene oxide) was uniformly added dropwise at a drop rate of 3 ml / min. The mixture was stirred at 60°C and 200 r / min for 4 hours, cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 8000 rpm for 10 minutes. The resulting precipitate was washed twice with anhydrous ethanol and dried in vacuo at 40°C for 10 hours to obtain modified graphene oxide. (3) The modified aramid fiber, lithium chloride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:0.2:8, stirred and dissolved at 80℃ and 200r / min for 10h, cooled to room temperature, and 0.08 times the modified graphene oxide of the modified aramid fiber was added, and ultrasonic dispersion was carried out for 20min to prepare a spinning solution; the spinning solution was added into a syringe, and silicone oil paper was used as the receiving material. Under the conditions of spinning voltage of 20kV, receiving distance of 15cm, liquid feed rate of 0.1mL / h, temperature of 20℃ and humidity of 48%, electrospinning was carried out for 10h to prepare an aramid nanofiber membrane; the aramid nanofiber membrane was immersed in 2,2-dimethoxy-2-phenylacetophenone solution, irradiated with ultraviolet light with a wavelength of 365nm for 0.5h, taken out and washed twice with deionized water, and vacuum dried at 20℃ for 10h to prepare a smoke filter material.

[0027] Example 2: A method for recycling waste aramid fabrics to prepare smoke filter materials, comprising the following preparation steps: (1) Cut the waste aramid fabric into 1.5 cm × 1.5 cm strips, place them in anhydrous ethanol for ultrasonic cleaning for 30 min, take them out and wash them with deionized water for 3 times, and vacuum dry them at 65 ° C for 7 h to obtain the waste aramid fabric recycling material; in a nitrogen atmosphere, the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate were mixed in a mass ratio of 1:40:0.003, reacted at room temperature for 11 h, and taken out. The pre-modified aramid fiber was washed with acetone three times and vacuum dried at 25°C for 11 hours to obtain a pre-modified aramid fiber. Under a nitrogen atmosphere, the pre-modified aramid fiber, dibutyl (allyl) phosphine, and N,N-dimethylacetamide were uniformly mixed in a mass ratio of 1:0.7:40, stirred at 85°C and 250 r / min for 71 hours, and N,N-dimethylacetamide was removed by vacuum distillation. The fiber was washed with anhydrous ethanol three times and vacuum dried at 45°C for 11 hours to obtain a modified aramid fiber. (2) Graphene oxide powder, N,N'-dicyclohexylcarboximide, and tetrahydrofuran were mixed in a mass ratio of 1:0.07:18, and ultrasonically dispersed for 30 minutes. 3-aminopropyltrimethoxysilane (1.3 times the mass of graphene oxide powder) was added, and stirred at 25°C and 250r / min for 5 hours. The mixture was filtered and washed with anhydrous ethanol 5 times, and vacuum dried at 55°C for 11 hours to obtain pre-modified graphene oxide. Pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, and N,N-dimethylformamide were mixed in a mass ratio of 1:0.07:18. The mixture was mixed in a molar ratio of 1:0.75:0.65:0.005:45, ultrasonically dispersed for 30 minutes, stirred at 65°C and 250 r / min for 50 minutes, and deionized water (0.2 times the mass of the pre-modified graphene oxide) was uniformly added dropwise at a drop rate of 3 ml / min. The mixture was stirred at 65°C and 250 r / min for 4.5 hours. The mixture was cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 9000 rpm for 11 minutes. The resulting precipitate was washed three times with anhydrous ethanol and dried in vacuo at 45°C for 11 hours to obtain modified graphene oxide. (3) The modified aramid fiber, lithium chloride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:0.35:8.5, stirred and dissolved at 85℃ and 250r / min for 11h, cooled to room temperature, and 0.1 times the modified graphene oxide of the modified aramid fiber was added, and ultrasonic dispersion was carried out for 30min to prepare a spinning solution; the spinning solution was added into a syringe, and silicone oil paper was used as the receiving material. Under the conditions of spinning voltage of 25kV, receiving distance of 20cm, liquid feed speed of 0.15mL / h, temperature of 25℃ and humidity of 50%, electrospinning was carried out for 11h to prepare an aramid nanofiber membrane; the aramid nanofiber membrane was immersed in 2,2-dimethoxy-2-phenylacetophenone solution, irradiated with ultraviolet light with a wavelength of 365nm for 1h, washed with deionized water 3 times after removal, and vacuum dried at 25℃ for 11h to prepare a smoke filter material.

[0028] Example 3: A method for recycling waste aramid fabrics to prepare smoke filter materials, comprising the following preparation steps: (1) Cut the waste aramid fabric into 1.5 cm × 1.5 cm strips, place them in anhydrous ethanol for ultrasonic cleaning for 40 min, take them out and wash them with deionized water for 4 times, and vacuum dry them at 70 ° C for 8 h to obtain the waste aramid fabric recycling material; in a nitrogen atmosphere, the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate were mixed in a mass ratio of 1:50:0.004, reacted at room temperature for 12 h, and taken out. The pre-modified aramid fiber was washed with acetone four times and vacuum dried at 30°C for 12 hours to obtain a pre-modified aramid fiber. Under a nitrogen atmosphere, the pre-modified aramid fiber, dibutyl (allyl) phosphine, and N,N-dimethylacetamide were uniformly mixed in a mass ratio of 1:0.8:50, stirred at 90°C and 300 r / min for 72 hours, and N,N-dimethylacetamide was removed by vacuum distillation. The fiber was washed with anhydrous ethanol four times and vacuum dried at 50°C for 12 hours to obtain a modified aramid fiber. (2) Graphene oxide powder, N,N'-dicyclohexylcarboximide and tetrahydrofuran were mixed in a mass ratio of 1:0.08:20, ultrasonically dispersed for 40 min, 3-aminopropyltrimethoxysilane (1.5 times the mass of graphene oxide powder) was added, stirred at 30 ° C, 300 r / min for 6 h, filtered and washed with anhydrous ethanol 6 times, and vacuum dried at 60 ° C for 12 h to obtain pre-modified graphene oxide; pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, N,N-dimethylformamide .... The mixture was uniformly mixed in a mass ratio of 1:0.8:0.7:0.006:50, ultrasonically dispersed for 40 minutes, stirred at 70°C and 300 r / min for 60 minutes, and deionized water (0.22 times the mass of the pre-modified graphene oxide) was uniformly added dropwise at a drop rate of 3 ml / min. The mixture was stirred at 70°C and 300 r / min for 5 hours, cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 10,000 rpm for 12 minutes. The resulting precipitate was washed four times with anhydrous ethanol and dried in vacuo at 50°C for 12 hours to obtain modified graphene oxide. (3) The modified aramid fiber, lithium chloride and N,N-dimethylacetamide were mixed uniformly in a mass ratio of 1:0.5:9, stirred and dissolved at 90℃ and 300r / min for 12h, cooled to room temperature, and 0.12 times the modified graphene oxide of the modified aramid fiber was added, and ultrasonic dispersion was carried out for 40min to prepare a spinning solution; the spinning solution was added into a syringe, and silicone oil paper was used as the receiving material. Under the conditions of spinning voltage of 30kV, receiving distance of 25cm, liquid feed rate of 0.2mL / h, temperature of 30℃ and humidity of 52%, electrospinning was carried out for 12h to prepare an aramid nanofiber membrane; the aramid nanofiber membrane was immersed in 2,2-dimethoxy-2-phenylacetophenone solution, irradiated with ultraviolet light with a wavelength of 365nm, and reacted for 1.5h. After being taken out, it was washed with deionized water 4 times and vacuum dried at 30℃ for 12h to prepare a smoke filter material.

[0029] Comparative Example 1: The difference between the method for preparing a smoke filter material by recycling waste aramid fabric in Comparative Example 1 and Example 2 lies in the difference in step (1). Step (1) is modified as follows: the waste aramid fabric is cut into 1.5 cm × 1.5 cm strips, ultrasonically cleaned in anhydrous ethanol for 30 min, washed three times with deionized water after removal, and vacuum dried at 65°C for 7 h to obtain the waste aramid fabric recycling material; under a nitrogen atmosphere, the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate are uniformly mixed in a mass ratio of 1:40:0.003, reacted at room temperature for 11 h, removed and washed three times with acetone, and vacuum dried at 25°C for 11 h to obtain the pre-modified aramid fiber. The remaining steps are the same as in Example 2.

[0030] Comparative Example 2: The difference between the method for preparing smoke filter material by recycling waste aramid fabric in Comparative Example 2 and Example 2 lies in the difference in step (2). Step (2) is modified as follows: graphene oxide powder, N,N'-dicyclohexylcarboximide and tetrahydrofuran are uniformly mixed in a mass ratio of 1:0.07:18, ultrasonically dispersed for 30 minutes, 3-aminopropyltrimethoxysilane (1.3 times the mass of graphene oxide powder) is added, stirred at 25°C and 250r / min for 5 hours, filtered and washed with anhydrous ethanol 5 times, and vacuum dried at 55°C for 11 hours to obtain pre-modified graphene oxide; pre-modified graphene oxide, 3-aminopropyltrimethoxysilane are mixed and the mixture is stirred at 25°C and 250r / min for 5 hours. Trimethoxysilane, sodium hydroxide, and N,N-dimethylformamide were uniformly mixed in a mass ratio of 1:0.75:0.005:45, and ultrasonically dispersed for 30 minutes. The mixture was stirred at 65°C and 250 rpm for 50 minutes. Deionized water (0.2 times the mass of the pre-modified graphene oxide) was uniformly added dropwise at a rate of 3 ml / min. The mixture was stirred at 65°C and 250 rpm for 4.5 hours. The mixture was cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 9000 rpm for 11 minutes. The resulting precipitate was washed three times with anhydrous ethanol and vacuum dried at 45°C for 11 hours to produce modified graphene oxide. The remaining steps were the same as in Example 2.

[0031] Comparative Example 3: The difference between the method for preparing smoke filter material by recycling waste aramid fabric in Comparative Example 3 and Example 2 lies in the difference in step (2). Step (2) is modified as follows: graphene oxide powder, N,N'-dicyclohexylcarboximide and tetrahydrofuran are mixed uniformly in a mass ratio of 1:0.07:18, ultrasonically dispersed for 30 minutes, 3-aminopropyltrimethoxysilane (1.3 times the mass of graphene oxide powder) is added, stirred at 25°C and 250r / min for 5 hours, filtered and washed with anhydrous ethanol 5 times, and vacuum dried at 55°C for 11 hours to obtain pre-modified graphene oxide; pre-modified graphene oxide, mercaptopropyl trimethoxysilane and 1.3 times the mass of graphene oxide powder are added, and the reaction is carried out at 25°C and 250r / min for 5 hours. Methoxysilane, sodium hydroxide, and N,N-dimethylformamide were uniformly mixed in a mass ratio of 1:0.65:0.005:45, and ultrasonically dispersed for 30 minutes. The mixture was stirred at 65°C and 250 rpm for 50 minutes. Deionized water (0.2 times the mass of the pre-modified graphene oxide) was uniformly added dropwise at a rate of 3 ml / min. The mixture was stirred at 65°C and 250 rpm for 4.5 hours. The mixture was cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 9000 rpm for 11 minutes. The resulting precipitate was washed three times with anhydrous ethanol and vacuum dried at 45°C for 11 hours to produce modified graphene oxide. The remaining steps were the same as in Example 2.

[0032] Comparative Example 4: The difference between the method for preparing smoke filter material by recycling waste aramid fabric in Comparative Example 4 and Example 2 is that step (2) is not performed, and step (3) is modified as follows: modified aramid fiber, lithium chloride, and N,N-dimethylacetamide are uniformly mixed in a mass ratio of 1:0.35:8.5, stirred and dissolved at 85°C and 250r / min for 11h, cooled to room temperature, and graphene oxide powder 0.1 times the modified aramid fiber is added, and ultrasonic dispersion is carried out for 30min to prepare a spinning solution; the spinning solution is added into a syringe. Using silicone oil paper as the receiving material, electrospinning was performed for 11 hours at a spinning voltage of 25 kV, a receiving distance of 20 cm, a liquid feed rate of 0.15 mL / h, a temperature of 25°C, and a humidity of 50% to produce an aramid nanofiber membrane. The aramid nanofiber membrane was then immersed in a 2,2-dimethoxy-2-phenylacetophenone solution and irradiated with ultraviolet light at a wavelength of 365 nm for 1 hour. The membrane was then removed and washed three times with deionized water and vacuum dried at 25°C for 11 hours to produce a smoke filter material. The remaining steps were the same as in Example 2.

[0033] Comparative Example 5: The difference between the method for preparing a smoke filter material by recycling waste aramid fabric in Comparative Example 5 and Example 2 lies in the difference in step (3). Step (3) is modified as follows: the modified aramid fiber, lithium chloride and N,N-dimethylacetamide are uniformly mixed in a mass ratio of 1:0.35:8.5, stirred and dissolved at 85°C and 250r / min for 11 hours, and cooled to room temperature to obtain a spinning solution; the spinning solution is added to a syringe, silicone oil paper is used as a receiving material, and electrostatic spinning is carried out for 11 hours under the conditions of a spinning voltage of 25kV, a receiving distance of 20cm, a liquid feed rate of 0.15mL / h, a temperature of 25°C and a humidity of 50% to obtain an aramid nanofiber membrane; the aramid nanofiber membrane is immersed in a 2,2-dimethoxy-2-phenylacetophenone solution, irradiated with ultraviolet light with a wavelength of 365nm for reaction for 1 hour, washed with deionized water three times after taking out, and vacuum dried at 25°C for 11 hours to obtain a smoke filter material. The remaining steps are the same as in Example 2.

[0034] Test Example 1: Filtration performance test: The filtration performance of the smoke filter materials obtained in each embodiment and comparative example was characterized using a TSI8130 automatic filter material tester. NaCl aerosol with an average size of 0.26 μm was used as the dust source. The samples were cut into squares with a side length of 14 cm and the test area was 100 cm. 2 , the air flow rate is 32L / min, calculate the filtration efficiency.

[0035] The results are shown in Table 1.

[0036]

[0037] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the smoke filter material prepared by the present invention has good filtering performance.

[0038] By comparison, the filtration efficiency of Examples 1 to 3 is greater than that of Comparative Example 5, indicating that the smoke filter material mainly plays a physical interception role in filtering solid particles. Solid particles with a particle size larger than the pore size of the smoke filter material will be intercepted, and particles with a smaller particle size will also be intercepted when passing through layers of fibers. Only solid particles with extremely small particle sizes will escape from the smoke filter material. Therefore, the pore size of the smoke filter material has an important influence on its filtration performance. Doping graphene oxide into the modified aramid fiber narrows the diameter distribution of the smoke filter material and distributes it to a smaller size, making the gas filtration path more tortuous, improving the retention of fine particles, and thus improving the filtration performance of the smoke filter material.

[0039] Test Example 2: Flame retardant performance test: According to GB / T6719-2009 "Technical Requirements for Bag Dust Collectors," flame-retardant filter materials should only smolder in flames and should not produce flames (i.e., an afterflame time of zero). The smoke filter materials obtained in each example and comparative example were cut into 300 mm x 89 mm specimens. The specimens were dried in a 105°C oven for 30 minutes, removed, and cooled in a desiccator for 40 minutes. The afterflame time of the specimens was then tested in accordance with GB / T5455-2014 "Fire Performance of Textiles - Determination of Vertical Damage Length, Smoldering, and Afterflame Time."

[0040] The results are shown in Table 2.

[0041]

[0042] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 1, it can be found that the smoke filter material prepared by the present invention has good flame retardant properties.

[0043] By comparison, the afterflame time of Examples 1 to 3 is shorter than that of Comparative Example 1, indicating that the modified aramid fiber is prepared by reacting the pre-modified aramid fiber with dibutyl (allyl) phosphine, and phosphorus is introduced into the material, thereby improving the flame retardant properties of the smoke filter material.

[0044] By comparison, the afterflaming time of Examples 1 to 3 is shorter than that of Comparative Examples 4 to 5, indicating that graphene oxide can promote the formation of a denser and continuous carbon layer during the combustion process, exert a physical barrier effect, and thus improve the flame retardant properties of the smoke filter material; graphene oxide is modified with 3-aminopropyltrimethoxysilane to improve the dispersibility of graphene oxide and aramid fiber, and silicon is introduced into the material, further improving the flame retardant properties of the smoke filter material.

[0045] Test Example 3: Antibacterial testing: The antibacterial rate against Escherichia coli and Staphylococcus aureus was tested according to GB / T20944.3-2008 “Evaluation of antibacterial properties of textiles”.

[0046] The results are shown in Table 3.

[0047]

[0048] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 3, it can be found that the smoke filter material prepared by the present invention has good antibacterial properties.

[0049] By comparison, the antibacterial rates of Escherichia coli and Staphylococcus aureus in Examples 1 to 3 are greater than those in Comparative Example 1, indicating that the chlorine element on the pre-modified aramid fiber reacts with dibutyl (allyl) phosphine to generate a quaternary phosphonium salt with antibacterial properties, thereby improving the antibacterial properties of the smoke filter material.

[0050] Test Example 4: Mechanical properties test: The smoke filter materials obtained in each embodiment and comparative example were cut into 15 cm × 4 cm specimens and tested using a tensile testing machine HD-609A at a clamping length of 60 mm, a tensile speed of 100 mm / min, a temperature of 20°C, and a relative humidity of 65%. Each sample was tested three times to test the breaking strength.

[0051] The results are shown in Table 4.

[0052]

[0053] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 4, it can be found that the smoke filter material prepared by the present invention has good mechanical properties.

[0054] By comparison, the breaking strength of Examples 1 to 3 is greater than that of Comparative Examples 2 and 4, indicating that when 2,2-dimethoxy-2-phenylacetophenone is used as a photoinitiator, under the irradiation of ultraviolet light, the double bonds on the modified aramid fiber and the thiol groups on the modified graphene oxide undergo a thiol-ene reaction to form a cross-linked network structure, thereby improving the mechanical properties of the smoke filter material.

[0055] By comparison, the fracture strength of Examples 1 to 3 is greater than that of Comparative Example 5, indicating that graphene oxide has good mechanical properties. Modification of graphene oxide with 3-aminopropyltrimethoxysilane improves the dispersibility of graphene oxide and aramid fiber, thereby enhancing the mechanical properties of the smoke filter material.

[0056] Test Example 5: Heavy metal ion adsorption performance test: Take 10 mg of each smoke filter material prepared in each example and comparative example, add it into 40 mL of 100 mg·L -1 The adsorption capacity was calculated by measuring the initial and equilibrium concentrations of the metal ions in the solution before and after adsorption. Qe = (C0 - Ce) V / m, where C0 (mg•L -1 ) represents the initial concentration of the solution, Ce(mg•L -1) represents the equilibrium concentration, V represents the volume of the solution, m represents the mass of the smoke filter material, Qe (mg•g -1 ) represents the adsorption amount at adsorption equilibrium.

[0057] The results are shown in Table 5.

[0058]

[0059] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 5 in Table 5, it can be found that the smoke filter material prepared by the present invention has good performance in adsorbing heavy metal ions.

[0060] By comparison, the adsorption amount of Examples 1 to 3 is greater than that of Comparative Examples 3 to 4, indicating that the modified graphene oxide is prepared by reacting the pre-modified graphene oxide with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane, and amino groups are introduced into the material. The amino groups can form complexes with heavy metal ions and adsorb heavy metal ions, thereby improving the heavy metal ion adsorption performance of the smoke filter material.

[0061] By comparison, the adsorption amount of Examples 1 to 3 is greater than that of Comparative Example 5, which shows that graphene oxide has a large specific surface area and contains a large number of oxygen-containing groups on the surface, which can adsorb heavy metal ions by electrostatic and complexation, thereby improving the performance of the smoke filter material in adsorbing heavy metal ions.

[0062] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for recycling waste aramid fabrics to prepare smoke filter materials, characterized in that: The smoke filter material is prepared by immersing an aramid nanofiber membrane in a 2,2-dimethoxy-2-phenylacetophenone solution and irradiating it with ultraviolet light; The aramid nanofiber membrane is prepared by electrostatic spinning after mixing modified aramid fiber and modified graphene oxide; The modified aramid fiber is prepared by cutting, washing, and drying waste aramid fabrics, and then reacting them with 3-chloropropyl isocyanate and dibutyl (allyl) phosphine in sequence; The modified graphene oxide is prepared by reacting graphene oxide powder with 3-aminopropyltrimethoxysilane to obtain pre-modified graphene oxide, which is then reacted with 3-aminopropyltrimethoxysilane and mercaptopropyltrimethoxysilane to obtain the modified graphene oxide.

2. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 1, characterized in that: The method comprises the following preparation steps: (1) Cutting, washing and drying waste aramid fabrics to obtain waste aramid fabric recycling materials; mixing the waste aramid fabric recycling materials, 3-chloropropyl isocyanate and dibutyltin dilaurate in a nitrogen atmosphere, washing and drying after taking out to obtain pre-modified aramid fiber; mixing the pre-modified aramid fiber, dibutyl (allyl) phosphine and N,N-dimethylacetamide in a nitrogen atmosphere, performing reduced pressure distillation, washing and drying to obtain modified aramid fiber; (2) Graphene oxide powder, N,N'-dicyclohexylcarboximide, and tetrahydrofuran are mixed evenly, ultrasonically dispersed, 3-aminopropyltrimethoxysilane is added and stirred for reaction, filtered, washed, and dried to obtain pre-modified graphene oxide; pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, and N,N-dimethylformamide are mixed evenly, deionized water is added dropwise at a uniform rate, stirred for reaction, residual water is removed with anhydrous calcium chloride, centrifuged, washed, and dried to obtain modified graphene oxide; (3) The modified aramid fiber, lithium chloride, and N,N-dimethylacetamide were mixed evenly, stirred to dissolve, and modified graphene oxide was added, and ultrasonic dispersion was performed to obtain a spinning solution; the spinning solution was added to a syringe and electrospun to obtain an aramid nanofiber membrane; the aramid nanofiber membrane was immersed in a 2,2-dimethoxy-2-phenylacetophenone solution, and irradiated with ultraviolet light with a wavelength of 365 nm to react, and then taken out, washed, and dried to obtain a smoke filter material.

3. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2, characterized in that: The modified aramid fiber described in step (1) includes the following preparation steps: cutting the waste aramid fabric into 1.5 cm × 1.5 cm strips, placing them in anhydrous ethanol for ultrasonic cleaning for 20 to 40 minutes, taking them out and washing them with deionized water for 2 to 4 times, and vacuum drying them at 60 to 70 ° C for 6 to 8 hours to obtain the waste aramid fabric recycling material; in a nitrogen atmosphere, mixing the waste aramid fabric recycling material, 3-chloropropyl isocyanate, and dibutyltin dilaurate in a mass ratio of 1: (30 to 50): (0.002 to 0.004) and reacting them at room temperature for 10 to 12 hours. After taking it out, it was washed with acetone for 2 to 4 times and vacuum dried at 20 to 30°C for 10 to 12 hours to obtain pre-modified aramid fiber; under a nitrogen atmosphere, the pre-modified aramid fiber, dibutyl (allyl) phosphine and N,N-dimethylacetamide were evenly mixed in a mass ratio of 1: (0.6 to 0.8): (30 to 50), stirred at 80 to 90°C and 200 to 300 r / min for 70 to 72 hours, and N,N-dimethylacetamide was removed by reduced pressure distillation. The fiber was washed with anhydrous ethanol for 2 to 4 times and vacuum dried at 40 to 50°C for 10 to 12 hours to obtain modified aramid fiber.

4. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2, characterized in that: The modified graphene oxide described in step (2) includes the following preparation steps: mixing graphene oxide powder, N,N'-dicyclohexylcarboximide, and tetrahydrofuran in a mass ratio of 1: (0.06~0.08): (15~20) evenly, ultrasonically dispersing for 20~40min, adding 3-aminopropyltrimethoxysilane in an amount of 1~1.5 times the mass of graphene oxide, stirring at 20~30℃, 200~300r / min for 4~6h, filtering and washing with anhydrous ethanol 4~6 times, and vacuum drying at 50~60℃ for 10~12h to obtain pre-modified graphene oxide; mixing pre-modified graphene oxide, 3-aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, sodium hydroxide, N,N-dimethylformamide in a mass ratio of 1: (0 .7~0.8): (0.6~0.7): (0.004~0.006): (40~50) were mixed evenly, ultrasonically dispersed for 20~40min, stirred at 60~70℃ and 200~300r / min for 40~60min, and deionized water (0.18~0.22 times the mass of the pre-modified graphene oxide) was uniformly added at a dropping rate of 3ml / min, and stirred at 60~70℃ and 200~300r / min for 4~5h. The mixture was cooled to room temperature, and residual water was removed with anhydrous calcium chloride. The mixture was centrifuged at 8000~10000rpm for 10~12min. The obtained precipitate was washed with anhydrous ethanol 2~4 times and vacuum dried at 40~50℃ for 10~12h to obtain modified graphene oxide.

5. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2, characterized in that: The smoke filter material described in step (3) includes the following preparation steps: uniformly mixing modified aramid fiber, lithium chloride, and N,N-dimethylacetamide in a mass ratio of 1: (0.2~0.5): (8~9), stirring and dissolving at 80~90°C and 200~300r / min for 10~12h, cooling to room temperature, adding 0.08~0.12 times of modified graphene oxide to the modified aramid fiber, ultrasonically dispersing for 20~40min to obtain a spinning solution; adding the spinning solution into a syringe, electrospinning for 10~12h to obtain an aramid nanofiber membrane; immersing the aramid nanofiber membrane in a 2,2-dimethoxy-2-phenylacetophenone solution, using ultraviolet light with a wavelength of 365nm, irradiating the reaction for 0.5~1.5h, taking out and washing with deionized water 2~4 times, and vacuum drying at 20~30°C for 10~12h to obtain a smoke filter material.

6. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2 or 4, characterized in that: The graphene oxide powder has a thickness of 1 nm and a single-layer sheet diameter of 0.5-10 μm.

7. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2 or 5, characterized in that: The electrospinning process parameters are as follows: silicone oil paper is used as the receiving material, the spinning voltage is 20-30 kV, the receiving distance is 15-25 cm, the liquid feeding speed is 0.1-0.2 mL / h, the temperature is 20-30° C., and the humidity is 48%-52%.

8. The method for preparing smoke filter material by recycling waste aramid fabric according to claim 2 or 5, characterized in that: The 2,2-dimethoxy-2-phenylacetophenone solution is prepared by mixing 2,2-dimethoxy-2-phenylacetophenone and acetone in a mass ratio of 1:(90-100).

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