Silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber and method for preparing the same

Abstract

The application provides a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber and a preparation method thereof, and belongs to the technical field of carbon fibers, and comprises the following steps: S1, chitosan solution preparation; S2, silver nitrate-chitosan solution preparation; S3, preparation of polyacrylonitrile fiber loaded with silver ions-chitosan on the surface; S4, pre-oxidation; S5, treatment of the pre-oxidized fiber; S6, carbonization and activation; and S7, drying.The silver ions-chitosan solution is used to uniformly load silver ions on the surface of the polyacrylonitrile fiber, the concentration of the silver ions-chitosan solution is 0.5-5 wt%, the surface pore size and distribution of the prepared activated carbon fiber can be controlled by the concentration of the acid solution, and the activated carbon fiber is rich in pore size and uniform in pore distribution, and the specific surface area is 800-1600 m 2 / g.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon fiber, in particular to a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber and a preparation method thereof. BACKGROUND

[0002] Activated carbon fiber is a kind of high-efficiency adsorption functional material developed in the early 1960s and gradually industrialized, which has the advantages of large specific surface area, moderate pore size, uniform distribution, fast adsorption speed, etc. Its products can be in the form of silk, paper, felt, cloth, etc. It is widely used in medical treatment, water purification, air purification, aviation, military, nuclear industry, food industry, etc.

[0003] At present, the development and application of high-performance polyacrylonitrile-based, phenolic-based, and pitch-based activated carbon fibers in China are still in the laboratory research stage. The main research institutions include the Institute of Coal Chemistry of the Chinese Academy of Sciences, Tsinghua University, Nanjing University, Tianjin University, Jilin University, Sun Yat-sen University, Beijing University of Chemical Technology, and East China University of Technology. The research focuses mainly on laboratory preparation process, modification method, and application effect test evaluation. However, the specific surface area of polyacrylonitrile-based activated carbon fiber is generally small, which limits its application.

[0004] Patent CN201611022481.1 discloses a preparation method of polyacrylonitrile-based activated carbon fiber and the application of the activated carbon fiber, which comprises the following steps: (1) performing three-stage heat treatment and pre-oxidation of polyacrylonitrile filaments in an oxidation furnace; (2) performing two-stage anaerobic carbonization treatment of the pre-oxidized polyacrylonitrile filaments. This method has complex operation steps and cannot prepare polyacrylonitrile-based activated carbon fiber with high specific surface area.

[0005] Silver metal has a highly active cation, which can release a large number of positive charges on the surface of the material. Bacteria or other organic organisms with negative charges floating in the air will be adsorbed to the surface. After the positive and negative charges react, the respiration of the bacteria is inhibited, and the cell wall and cell membrane of the bacteria are completely deformed and ruptured, losing the ability to reproduce and survive, and causing "lysis death". In addition, heavy metals have super strong degradation function, which can destroy the enzyme system in the bacteria when the bacteria are adsorbed on the surface of silver, affecting the normal metabolism of the bacteria, thereby causing the death of the bacteria. Generally, antibiotics can only act on an average of 6 kinds of bacteria, but silver can eliminate 650 kinds of bacteria.

[0006] It is necessary to prepare an activated carbon fiber with high specific surface area and load high-concentration silver, so as to prepare a fiber with good antibacterial performance, which has broad application prospects.

[0007] CN202011239732.8 discloses a durable antibacterial and mildew-resistant fiber and its application, comprising activated carbon fiber, nano-level antibacterial agent, and polyacrylonitrile; the weight proportions of each raw material are: 15-30 parts activated carbon fiber, 60-70 parts polyacrylonitrile, and the nano-level antibacterial agent is 3-8% of the weight of activated carbon fiber. This invention uses activated carbon fiber, nano-level antibacterial agent, and polyacrylonitrile as raw materials. The activated carbon fiber is PAN-based carbon fiber, using the same substrate as polyacrylonitrile, resulting in good fiber mechanical properties. The activated carbon fiber adsorbs the nano-level antibacterial agent, which is adsorbed into the pores of the activated carbon fiber, improving wash fastness and ensuring the fiber's antibacterial effect, whiteness value, and mechanical properties. Furthermore, during the preparation process of the durable antibacterial and mildew-resistant fiber obtained by this invention, the fiber undergoes alternating tension heat treatment after stretching at a temperature of 250-290℃, which improves the fiber's breaking strength and elongation at break. Summary of the Invention

[0008] The purpose of this invention is to provide a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber and its preparation method. Silver ions are uniformly loaded onto the surface of polyacrylonitrile fibers using a silver ion-chitosan solution with a concentration of 0.5-5 wt%. The pore size and distribution of the prepared activated carbon fiber surface can be controlled by the concentration of an acid solution (0.5-2.0 mol / L), resulting in activated carbon fibers with abundant and uniform pore size. The specific surface area of ​​the activated carbon fiber can be controlled by the activation temperature, the flow rate of water vapor or a mixture of carbon dioxide and water vapor, and the activation time, achieving a specific surface area of ​​800-1600 m². 2 / g.

[0009] The technical solution of this invention is implemented as follows:

[0010] This invention provides a method for preparing silver-loaded antibacterial polyacrylonitrile-based activated carbon fibers, comprising the following steps:

[0011] S1. Preparation of chitosan solution: Chitosan is dissolved in acid solution at room temperature and stirred at room temperature for 2-6 hours to obtain a 1-10 wt% chitosan solution;

[0012] S2. Preparation of silver nitrate-chitosan solution: Add silver nitrate to the chitosan solution prepared in step S1, sonicate at room temperature for 30-60 min, and then magnetically stir for 30-60 min to obtain a 0.5-5 wt% silver ion-chitosan solution.

[0013] S3. Preparation of polyacrylonitrile fibers with surface-loaded silver ions-chitosan: Immerse polyacrylonitrile fibers in the silver ion-chitosan solution prepared in step S2 for 0.5-4 hours, air dry naturally for 12-24 hours, and then bake at 100℃ for 1-3 hours.

[0014] S4. Pre-oxidation: the silver ion-chitosan loaded polyacrylonitrile fiber prepared in step S3 is pre-oxidized at 150-300°C for 60-120 min to obtain a pre-oxidized fiber;

[0015] S5. Treatment of the pre-oxidized fiber: the pre-oxidized fiber prepared in step S4 is soaked in a solution for 2-6 h, naturally air-dried for 12-24 h, and then baked at 100°C for 1-3 h;

[0016] S6. Carbonization activation: the pre-oxidized fiber treated in step S5 is heated to 600-1000°C under inert gas protection, and then carbonized and activated by passing in a gas for 10-240 min, and cooled to obtain an activated carbon fiber;

[0017] S7. Drying: the activated carbon fiber treated in step S6 is washed with deionized water and dried to obtain a silver-loaded antibacterial activated carbon fiber.

[0018] As a further improvement of the present application, the chitosan in step S1 has a molecular weight of 20-100 thousand; and the acid solution is a 3-10 wt% formic acid, acetic acid, hydrochloric acid or benzoic acid solution.

[0019] As a further improvement of the present application, the polyacrylonitrile fiber in step S3 is obtained by wet spinning of an acrylonitrile polymerization solution.

[0020] As a further improvement of the present application, the solution in step S5 is a phosphoric acid, boric acid or a mixture of the two.

[0021] As a further improvement of the present application, the solute concentration of the solution is 0.5-2.0 mol / L.

[0022] As a further improvement of the present application, the gas in step S6 is water vapor or a mixture of carbon dioxide and water vapor with a molar ratio of (1-3):1.

[0023] As a further improvement of the present application, the flow rate of the gas is 10-100 mL per kg of pre-oxidized fiber per minute.

[0024] As a further improvement of the present application, the inert gas in step S6 is N2 or Ar, and the heating rate under the inert gas protection is 2-30°C / min.

[0025] The present application further protects a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber prepared by the above preparation method.

[0026] As a further improvement of the present application, the silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber has a specific surface area of 800-1600 m 2 / g.

[0027] The present application has the following advantages: the present application uniformly loads silver ions on the surface of polyacrylonitrile fibers by using a silver ion-chitosan solution, the concentration of the silver ion-chitosan solution is 0.5-5wt%, the surface pore size and distribution of the prepared activated carbon fiber can be controlled by the concentration of the acid solution, the solution concentration is 0.5-2.0mol / L, and the obtained is an activated carbon fiber with rich pore size and uniform distribution. The specific surface area of the activated carbon fiber can be controlled by the activation temperature, the flow rate of water vapor or carbon dioxide and water vapor mixed gas, and the activation time, and the specific surface area is 800-1600m 2 / g.

[0028] The silver loading amount of the prepared silver-loaded antibacterial type polyacrylonitrile-based activated carbon fiber can improve the antibacterial effect of the fiber, when the initial silver loading amount of the fiber reaches 1.5mg / g, the inhibition rate of the silver-loaded activated carbon fiber on escherichia coli and staphylococcus aureus can reach 99.99%, and when the initial silver loading amount reaches 3mg / g, the inhibition rate on candida albicans can reach 99.99%. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0030] Embodiment 1

[0031] 3g of chitosan (average molecular weight, 60,000) was dissolved in 147g of 5wt% formic acid solution at room temperature, stirred at room temperature for 4h, and 2wt% chitosan solution was obtained; 4.7g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonically treated for 30min at room temperature, and then magnetically stirred for 30min to obtain 3wt% silver nitrate-chitosan solution; 100g of 12K polyacrylonitrile fiber (single filament diameter 15-20μm) was soaked in the silver nitrate-chitosan solution for 4h, naturally air-dried for 12h, and then baked at 100℃ for 2h; the polyacrylonitrile fiber loaded with silver nitrate-chitosan was pre-oxidized at 200℃ for 80min; then the pre-oxidized fiber was soaked in a 1.5mol / L phosphoric acid solution for 6h; naturally air-dried for 24h, and pre-baked at 100℃ for 2h; the treated sample was heated to 800℃ at a heating rate of 10℃ / min under N2 protection, and then carbonized and activated by introducing water vapor, the gas flow rate was 5mL / min, and the time was 30min, and after cooling and washing, the silver-loaded antibacterial type polyacrylonitrile-based activated carbon fiber was obtained. The specific surface area was 936m 2 / g.

[0032] Example 2

[0033] At room temperature, 50 g of chitosan (average molecular weight, 43,000) was dissolved in 1200 g of 3 wt% acetic acid solution, stirred at room temperature for 4 h to obtain a 4 wt% chitosan solution; 19 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic treatment for 40 min at room temperature, and then magnetic stirring for 60 min to obtain a 1.5 wt% silver nitrate-chitosan solution; 500 g of polyacrylonitrile fiber 12K filament (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 2 h, naturally air-dried for 12 h, and then baked at 100°C for 4 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 260°C for 80 min; then the pre-oxidized fiber was soaked in a 2 mol / L phosphoric acid solution for 4 h; naturally air-dried for 24 h, and pre-baked at 100°C for 4 h; the treated sample was heated to 1000°C at a heating rate of 10°C / min under N2 protection, and then carbonized and activated by introducing water vapor, with a gas flow rate of 20 mL / min for 2 h, to obtain a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 1462 m 2 / g.

[0034] Example 3

[0035] At room temperature, 30 g of chitosan (average molecular weight, 55,000) was dissolved in 970 g of 5 wt% formic acid solution, stirred at room temperature for 3 h to obtain a 3 wt% chitosan solution; 20.4 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic treatment for 60 min at room temperature, and then magnetic stirring for 60 min to obtain a 2 wt% silver nitrate-chitosan solution; 300 g of polyacrylonitrile fiber 24K filament (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 6 h, naturally air-dried for 12 h, and then baked at 100°C for 3 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 240°C for 90 min; then the pre-oxidized fiber was soaked in a 2 mol / L boric acid solution for 5 h; naturally air-dried for 24 h, and pre-baked at 100°C for 3 h; the treated sample was heated to 950°C at a heating rate of 15°C / min under N2 protection, and then carbonized and activated by introducing water vapor, with a gas flow rate of 10 mL / min for 60 min, to obtain a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 1206 m 2 / g.

[0036] Example 4

[0037] At room temperature, 5 g of chitosan (average molecular weight, 60,000) was dissolved in 195 g of 3 wt% hydrochloric acid solution, stirred at room temperature for 4 h, to obtain a 2.5 wt% chitosan solution; 6.2 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic for 40 min at room temperature, and then magnetic stirring for 40 min, to obtain a 3 wt% silver nitrate-chitosan solution; 100 g of 48K polyacrylonitrile fiber (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 4 h, naturally air-dried for 12 h, and then baked at 100°C for 3 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 280°C for 50 min; then the pre-oxidized fiber was soaked in a 1.5 mol / L phosphoric acid solution for 6 h; naturally air-dried for 20 h, and pre-baked at 100°C for 3 h; the treated sample was heated to 1000°C at an argon gas flow rate of 10 mL / min and a heating rate of 15°C / min, and then carbonized and activated by introducing water vapor at a gas flow rate of 5 mL / min for 80 min, to obtain a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 713 m 2 / g.

[0038] Example 5

[0039] At room temperature, 15 g of chitosan (average molecular weight, 43,000) was dissolved in 285 g of 3 wt% benzoic acid solution, stirred at room temperature for 2 h, to obtain a 5 wt% chitosan solution; 12.5 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic for 50 min at room temperature, and then magnetic stirring for 50 min, to obtain a 4 wt% silver nitrate-chitosan solution; 200 g of 12K polyacrylonitrile fiber (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 4 h, naturally air-dried for 12 h, and then baked at 100°C for 2 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 220°C for 80 min; then the pre-oxidized fiber was soaked in a mixed solution of 1.5 mol / L phosphoric acid and 1.5 mol / L boric acid (volume ratio 1:1) for 4 h; naturally air-dried for 24 h, and pre-baked at 100°C for 2 h; the treated sample was heated to 900°C at a nitrogen gas flow rate of 20 mL / min and a heating rate of 15°C / min, and then carbonized and activated by introducing a mixed gas of carbon dioxide and water vapor (molar ratio 3:1) at a gas flow rate of 8 mL / min for 2 h, to obtain a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 1583 m 2 / g.

[0040] Example 6

[0041] At room temperature, 30 g of chitosan (average molecular weight, 38,000) was dissolved in 270 g of 10 wt% formic acid solution, stirred at room temperature for 2 h to obtain a 10 wt% chitosan solution; 15.8 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic treatment for 60 min at room temperature, and then magnetic stirring for 60 min to obtain a 5 wt% silver nitrate-chitosan solution; 200 g of 48K polyacrylonitrile fiber (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 4 h, naturally air-dried for 24 h, and then baked at 100°C for 3 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 280°C for 60 min; then the pre-oxidized fiber was soaked in a mixed solution of 2 mol / L phosphoric acid and 2 mol / L boric acid (volume ratio 1:1) for 6 h; naturally air-dried for 24 h, and then pre-baked at 100°C for 3 h; the treated sample was heated to 1000°C at a heating rate of 10°C / min under N2 protection, and then carbonized and activated by introducing a mixed gas of carbon dioxide and water vapor (molar ratio 2:1) at a gas flow rate of 5 mL / min for 60 min, to obtain a silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 983 m 2 / g.

[0042] Compared with the prior art, the silver ion-chitosan solution is used to uniformly load silver ions on the surface of the polyacrylonitrile fiber, the concentration of the silver ion-chitosan solution is 0.5-5 wt%, the surface pore size and distribution of the prepared activated carbon fiber can be controlled by the concentration of the acid solution, the concentration of the solution is 0.5-2.0 mol / L, and the obtained is an activated carbon fiber with rich pore size and uniform distribution. The specific surface area of the activated carbon fiber can be controlled by the activation temperature, the flow rate of water vapor or the mixed gas of carbon dioxide and water vapor, and the activation time, and the specific surface area is 800-1600 m 2 / g.

[0043] Comparative Example 1

[0044] Compared with Example 5, the difference is that after the silver nitrate-chitosan loaded polyacrylonitrile fiber is pre-oxidized, the pre-oxidized fiber is not treated with an acid solution, but is directly carbonized and activated by introducing a mixed gas of carbon dioxide and water vapor (molar ratio 3:1) under N2 protection, and the specific surface area of the prepared activated carbon fiber is 446 m 2 / g.

[0045] At room temperature, 15 g of chitosan (average molecular weight, 43,000) was dissolved in 285 g of 3 wt% benzoic acid solution, stirred at room temperature for 2 h, to obtain a 5 wt% chitosan solution; 12.5 g of silver nitrate powder was weighed and added to the chitosan solution, ultrasonic for 50 min at room temperature, and then magnetic stirring for 50 min, to obtain a 4 wt% silver nitrate-chitosan solution; 200 g of 12K polyacrylonitrile fiber (single filament diameter 15-20 μm) was soaked in the silver nitrate-chitosan solution for 4 h, naturally air-dried for 12 h, and then baked at 100 ℃ for 2 h; the silver nitrate-chitosan loaded polyacrylonitrile fiber was pre-oxidized at 220 ℃ for 80 min; then the pre-oxidized fiber was heated to 900 ℃ under N2 protection, with a heating rate of 15 ℃ / min, and carbonized and activated by introducing a mixed gas of carbon dioxide and water vapor (molar ratio 3:1) at a gas flow rate of 8 mL / min for 2 h, to obtain the silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber. The specific surface area was 446 m 2 / g.

[0046] Test Example 1

[0047] The antibacterial performance of Examples 1-6 and Comparative Example 1 was tested, and the results are shown in Table 1.

[0048] The test was performed according to the test method 1 of standard GB21551.2-2010, the detection bacteria were Escherichia coli, Staphylococcus aureus, and Candida albicans, each example and comparative example was tested in parallel for 5 times, and the average value was taken. The results are shown in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] As shown in the above table, the silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber prepared by the present application has good antibacterial and bacteriostatic effects.

[0053] The silver loading amount in the silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber prepared by the present application can improve the antibacterial effect of the fiber. When the initial silver loading amount of the fiber reaches 1.5 mg / g, the inhibition rate of the silver-loaded activated carbon fiber to Escherichia coli and Staphylococcus aureus can reach 99.99%, and when the initial silver loading amount reaches 3 mg / g, the inhibition rate to Candida albicans can reach 99.99%.

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing silver-loaded antibacterial polyacrylonitrile-based activated carbon fibers, characterized in that, Includes the following steps: S1. Preparation of chitosan solution: Chitosan is dissolved in acid solution at room temperature and stirred at room temperature for 2-6 hours to obtain a 1-10 wt% chitosan solution; S2. Preparation of silver nitrate-chitosan solution: Add silver nitrate to the chitosan solution prepared in step S1, sonicate at room temperature for 30-60 min, and then magnetically stir for 30-60 min to obtain a 0.5-5 wt% silver ion-chitosan solution; S3. Preparation of polyacrylonitrile fibers with surface-loaded silver ions-chitosan: Immerse polyacrylonitrile fibers in the silver ion-chitosan solution prepared in step S2 for 0.5-4 hours, allow to air dry naturally for 12-24 hours, and then bake at 100℃ for 1-3 hours; S4. Pre-oxidation: The polyacrylonitrile fibers with surface-loaded silver ions-chitosan prepared in step S3 are pre-oxidized at 150-300℃ for 60-120 min to obtain pre-oxidized fibers; S5. Treatment of pre-oxidized fiber: Soak the pre-oxidized fiber prepared in step S4 in solution for 2-6 hours; let it air dry naturally for 12-24 hours, and then bake it at 100℃ for 1-3 hours; the solution is phosphoric acid, boric acid or a mixture of the two, and the solute concentration of the solution is 0.5-2.0 mol / L; S6. Carbonization and Activation: The pre-oxidized fiber treated in step S5 is heated to 600-1000℃ under inert gas protection at a heating rate of 2-30℃ / min, held at this temperature, and carbonized and activated by introducing gas for 10-240min. After cooling, activated carbon fiber is obtained. The gas is water vapor or a mixture of carbon dioxide and water vapor, with a molar ratio of (1-3):

1. The gas flow rate is 10-100mL per kilogram of pre-oxidized fiber per minute. S7. Drying: The activated carbon fibers treated in step S6 are washed with deionized water and dried to obtain silver-loaded antibacterial activated carbon fibers with a specific surface area of ​​800-1600 m2 / g and an antibacterial rate of not less than 99.99% against Escherichia coli, Staphylococcus aureus and Candida albicans.

2. The method for preparing silver-loaded antibacterial polyacrylonitrile-based activated carbon fibers according to claim 1, characterized in that, The chitosan in step S1 has a molecular weight between 20,000 and 100,000; the acid solution is a 3-10 wt% solution of formic acid, acetic acid, hydrochloric acid, or benzoic acid.

3. The method for preparing silver-loaded antibacterial polyacrylonitrile-based activated carbon fibers according to claim 1, characterized in that, The polyacrylonitrile fiber described in step S3 is obtained by wet spinning from an acrylonitrile polymerization solution.

4. The method for preparing silver-loaded antibacterial polyacrylonitrile-based activated carbon fibers according to claim 1, characterized in that, The inert gas mentioned in step S6 is N2 or Ar.

5. A silver-loaded antibacterial polyacrylonitrile-based activated carbon fiber prepared by the preparation method according to any one of claims 1-4.

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