Method for preparing active carbon fiber with assistance of supercritical carbon dioxide, active carbon fiber and application of active carbon fiber

Abstract

The invention relates to the technical field of functional carbon fibers, and discloses a method for preparing active carbon fibers assisted by supercritical carbon dioxide, the active carbon fibers and application of the active carbon fibers. The method comprises the following steps: (S1) carrying out spinning and pre-oxidation treatment on a spinning solution to obtain pre-oxidized fibers; (S2) under a first supercritical carbon dioxide condition, contacting the pre-oxidized fiber, a silver nitrate solution and a surfactant to obtain a silver-containing pre-oxidized fiber; and (S3) carrying out low-temperature carbonization, acidification treatment and high-temperature carbonization treatment on the silver-containing pre-oxidized fiber to obtain the silver-containing active carbon fiber. According to the method, the silver particles are deposited under the assistance of supercritical carbon dioxide, the silver-containing active carbon fiber with the high specific surface area can be prepared, and the silver-containing active carbon fiber has the good antibacterial performance.

Description

Technical Field

[0001] This invention relates to the field of functional carbon fiber technology, specifically to a method for preparing activated carbon fiber with supercritical carbon dioxide assistance, as well as activated carbon fiber and its applications. Background Technology

[0002] Activated carbon fiber (ACF) shares similar characteristics with activated carbon, such as a large specific surface area and a large number of microporous structures, resulting in superior adsorption performance. However, activated carbon fiber also exhibits superior mechanical properties and is easier to recycle and reuse than activated carbon. Therefore, it is widely used in wastewater treatment, air purification, hydrogen storage, solvent recovery, pharmaceuticals, carriers, anti-toxic materials, and hydrometallurgy.

[0003] The antibacterial mechanism of silver particles or silver ions mainly consists of five aspects. First, silver ions (Ag) + It can firmly adhere to the cell membrane using Coulomb's attraction, and reacts with the cell wall via peptidoglycan, causing damage to the bacteria's intrinsic components or impairing its production function; Ag + Accumulation on the cell membrane surface affects bacterial membrane permeability and can disrupt microbial electron transport and substance transport systems. Ag+ can block ATP production and disrupt DNA replication. Ag+ can penetrate the cell wall and enter the cell, where it binds to certain groups within bacteria and other organisms, causing protein coagulation, resulting in cell death due to loss of the ability to divide and proliferate. + It can act as a catalytic active center, activate surrounding oxygen, generate hydroxyl radicals and reactive oxygen ions, destroy the proliferation ability of microbial cells, and inhibit or kill bacteria.

[0004] CN106676676B discloses a blood filter based on polyacrylonitrile-based activated carbon fiber. The method involves first subjecting polyacrylonitrile fibers to a three-stage heat treatment to obtain pre-oxidized fibers, then performing low-temperature carbonization at 600-900℃ in a nitrogen atmosphere, followed by activation for 60-200 minutes in a nitrogen:water vapor volume ratio of 1:1 at 700-1000℃ to obtain the final activated carbon fiber. This activation method is cumbersome and yields activated carbon fibers with a low specific surface area.

[0005] CN112226847A discloses a durable antibacterial and antifungal fiber and its applications. It mainly utilizes activated carbon fibers to adsorb antibacterial agents. The carbon fiber chips with adsorbed antibacterial agents are extruded with polyacrylonitrile using a twin-screw extruder to produce antibacterial fibers. The fibers are then subjected to tension heat treatment, oiling, and winding to produce durable antibacterial fibers. However, the antibacterial fibers prepared by this method only utilize the properties of the antibacterial agents; the fibers themselves do not possess adsorption properties, resulting in relatively limited performance characteristics.

[0006] Therefore, researching and developing an activated carbon fiber with good antibacterial properties is of great significance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies in preparing activated carbon fibers, such as low specific surface area and poor antibacterial properties. This invention provides a method for preparing activated carbon fibers with supercritical carbon dioxide assistance, as well as the activated carbon fibers and their applications. This invention utilizes supercritical carbon dioxide to assist in the deposition of silver particles, which can prepare silver-containing activated carbon fibers with high specific surface area and better antibacterial properties.

[0008] To achieve the above objectives, a first aspect of the present invention provides a method for preparing silver-containing activated carbon fibers with supercritical carbon dioxide assistance, wherein the method comprises:

[0009] (S1) The spinning solution is subjected to spinning and pre-oxidation treatment to obtain pre-oxidized fiber;

[0010] (S2) Under the first supercritical carbon dioxide condition, the pre-oxidized fiber, silver nitrate solution and surfactant are contacted to obtain silver-containing pre-oxidized fiber;

[0011] (S3) The silver-containing pre-oxidized fiber is subjected to low-temperature carbonization, acidification and high-temperature carbonization to obtain silver-containing activated carbon fiber.

[0012] A second aspect of the present invention provides a silver-containing activated carbon fiber prepared by the aforementioned method.

[0013] A third aspect of the present invention provides an application of the aforementioned silver-containing activated carbon fiber in water purification.

[0014] Through the above technical solution, the present invention has the following beneficial effects:

[0015] (1) The activated carbon fibers prepared by this invention are obtained by supercritical carbon dioxide-assisted deposition of silver particles and assisted acid activation. This is a new method for preparing high specific surface area activated carbon fibers with high silver particle deposition. The specific surface area of ​​the obtained activated carbon fibers can reach 1000-3000 m². 2 / g.

[0016] (2) The present invention utilizes supercritical carbon dioxide to assist in the deposition of silver particles, which can greatly increase the amount of silver particles deposited.

[0017] (3) At the same time, supercritical carbon dioxide is environmentally friendly and pollution-free. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] As previously stated, the first aspect of this invention provides a method for preparing silver-containing activated carbon fibers using supercritical carbon dioxide assistance, wherein the method includes:

[0020] (S1) The spinning solution is subjected to spinning and pre-oxidation treatment to obtain pre-oxidized fiber;

[0021] (S2) Under the first supercritical carbon dioxide condition, the pre-oxidized fiber, silver nitrate solution and surfactant are contacted to obtain silver-containing pre-oxidized fiber;

[0022] (S3) The silver-containing pre-oxidized fiber is subjected to low-temperature carbonization, acidification and high-temperature carbonization to obtain silver-containing activated carbon fiber.

[0023] The inventors of this invention have discovered that using supercritical carbon dioxide to assist in the deposition of silver particles can significantly increase the amount of silver particles deposited, enabling the preparation of polyacrylonitrile activated carbon fibers with high specific surface area. Furthermore, supercritical carbon dioxide is environmentally friendly and pollution-free. In a further preferred embodiment, the inventors have found that before high-temperature carbonization, further activation treatment of the acidified fibers with supercritical carbon dioxide is performed. Because supercritical carbon dioxide possesses both liquid and fluid properties, the preparation of activated carbon fibers does not cause micropore collapse or leave any organic solvent residue.

[0024] According to the present invention, in step (S1), the spinning solution is spun into fibers (preferably polyacrylonitrile fibers) by wet spinning or dry-jet wet spinning. There are no specific limitations on the spinning conditions. In this invention, the spinneret orifice diameter is 0.05-0.06 mm, the number of spinneret orifices is 2800-3200, the solid content of the spinning solution is 11-12%, the coagulation bath temperature is around 0°C, the coagulation bath concentration is 10-15%, the hot drawing process is conducted with hot water at 90-96°C, and the draw ratio is 10-12. Preferably, the spinneret orifice diameter is 0.055 mm, the number of spinneret orifices is 3000, the solid content of the spinning solution is 11.8%, the coagulation bath temperature is 0°C, the coagulation bath concentration is 12%, the hot drawing process is conducted with hot water at 94°C, and the draw ratio is 10.

[0025] In this invention, the coagulation bath can be one or more solvents selected from dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and sodium thiocyanate (NaSCN). According to this invention, the spinning solution includes one or more of polyacrylonitrile-based spinning solution, viscose-based spinning solution, and pitch-based spinning solution, preferably polyacrylonitrile-based spinning solution.

[0026] According to the present invention, the spinning solvent in the spinning solution is selected from one or more of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and dimethylacetamide (DMAc).

[0027] According to the present invention, in step (S2), the pre-oxidation is carried out in four temperature zones, namely 210-230℃, 230-240℃, 250-260℃, and 270-280℃, and the pre-oxidation time is 45-60 minutes; preferably, the pre-oxidation is carried out in four temperature zones, namely 220℃, 235℃, 255℃, and 275℃, and the pre-oxidation time is 45 minutes.

[0028] According to the present invention, in step (S2), the first supercritical carbon dioxide conditions include: a temperature of 35-90°C, a pressure of 8-16 MPa, and a treatment time of 10-30 min; preferably, the temperature is 40-80°C, the pressure is 10-14 MPa, and the treatment time is 15-25 min.

[0029] According to the present invention, in step (S2), the first supercritical carbon dioxide condition further includes: purging air 2-5 times and depressurizing for 1-3 minutes; preferably, it is carried out in a reactor under the condition of a stirring rate of 100-500 rpm.

[0030] According to the present invention, the concentration of the silver nitrate solution is 0.5-2 mol / L, preferably 0.8-1.8 mol / L.

[0031] According to the present invention, the surfactant is selected from one or more of perfluoropolyether phosphate ethers, phosphate esters and alkylbenzene sulfonates, preferably perfluoropolyether phosphate ethers.

[0032] According to the present invention, the mass ratio of the surfactant to the silver nitrate solution is (0.005-0.02):1, preferably (0.01-0.015):1.

[0033] According to the present invention, the conditions for low-temperature carbonization include: a temperature of 300-800°C and a time of 2-15 min; preferably, the heating rate during the low-temperature carbonization process is 5-10°C / min.

[0034] According to the present invention, the acidification treatment conditions include: using phosphoric acid and / or hydrochloric acid, preferably, the concentration of the acid is 0.1-3 g / ml, and the soaking time is 5-18 h; more preferably, the concentration of the acid is 0.2-3 g / ml, and the soaking time is 5-10 h.

[0035] According to the present invention, the conditions for high-temperature carbonization include: high-temperature carbonization for 2-15 minutes at a temperature of 1200-1600°C under inert gas protection; preferably, the heating rate during the high-temperature carbonization process is 5-30°C / min.

[0036] According to the present invention, the inert gas is N2 or Ar.

[0037] According to the present invention, in a preferred embodiment, the method further includes: in step (S3), before performing the high-temperature carbonization treatment, subjecting the fiber obtained by the acidification treatment to a second supercritical carbon dioxide activation treatment; preferably, the conditions for the second supercritical carbon dioxide activation treatment include: a temperature of 50-140°C, a pressure of 8-20 MPa, and a treatment time of 10-50 min; preferably, a temperature of 60-130°C, a pressure of 9-18 MPa, and a treatment time of 15-45 min.

[0038] According to the present invention, in step (S3), the second supercritical carbon dioxide condition further includes: purging air 2-5 times, with a depressurization time of 1-3 minutes.

[0039] According to a preferred embodiment of the present invention, a method for preparing silver-containing activated carbon fibers with supercritical carbon dioxide assistance includes:

[0040] (S1) Polyacrylonitrile spinning solution is used to prepare polyacrylonitrile fibers by wet spinning. The fibers are then subjected to pre-oxidation treatment to obtain pre-oxidized polyacrylonitrile fibers.

[0041] (S2) In a supercritical reactor, the prepared pre-oxidized fiber is placed in a supercritical reactor containing a surfactant perfluoropolyether phosphate ether / silver nitrate solution and the reaction cover is fixed. After the air in the reactor is removed by CO2 several times, CO2 is introduced to a certain pressure. After reacting for a period of time under stirring conditions, CO2 gas is released to depressurize and the prepared silver-containing pre-oxidized fiber is taken out.

[0042] (S3) The silver-containing pre-oxidized fibers after treatment are subjected to low-temperature carbonization under inert gas protection. The resulting low-temperature carbonized fibers are then immersed in an acid solution to obtain pretreated active low-temperature carbon fibers.

[0043] (S4) Then, in a supercritical reactor, the obtained pre-oxidized fiber is placed into a supercritical carbon dioxide reactor and the reaction cover is fixed. After the air in the reactor is removed by CO2 several times, CO2 is introduced to a certain pressure. After reacting for a period of time, CO2 gas is released to depressurize and the prepared active low-temperature carbon fiber is taken out.

[0044] (S5) The porous activated low-temperature carbon fiber after treatment is subjected to high-temperature carbonization under inert gas protection, and after cooling, activated carbon fiber containing silver particles is obtained.

[0045] A second aspect of the present invention provides a silver-containing activated carbon fiber prepared by the aforementioned method.

[0046] According to the present invention, in a preferred embodiment, the silver-containing activated carbon fiber is a silver-containing polyacrylonitrile-based activated carbon fiber.

[0047] According to the present invention, the activated carbon fiber prepared by the present invention is obtained by supercritical carbon dioxide-assisted deposition of silver particles and assisted acid activation. This is a novel method for preparing high-specific-surface-area activated carbon fibers with high silver particle deposition content. The specific surface area of ​​the silver-containing activated carbon fiber obtained is 1000-3000 m². 2 / g, preferably 1121-2983m 2 / g; the total pore volume is 0.5-0.9 ml / g, preferably 0.58-0.86 ml / g.

[0048] According to the present invention, the method utilizes supercritical carbon dioxide to assist in the deposition of silver particles, which can greatly increase the amount of silver particles deposited. The silver loading in the silver-containing activated carbon fiber is 3-60 mg / g, preferably 4-60 mg / g, and more preferably 5-60 mg / g.

[0049] A third aspect of the present invention provides an application of the aforementioned silver-containing activated carbon fiber in water purification.

[0050] According to the present invention, the purified water can be used to purify domestic water and / or industrial water.

[0051] The present invention will be described in detail below through embodiments.

[0052] In the following examples and comparative examples:

[0053] The test was conducted according to Test Method 1 of GB21551.2-2010, using the film-applied method. The bacteria tested were Escherichia coli, Staphylococcus aureus, and Candida albicans.

[0054] Mechanical performance parameters were measured according to the method in GB / T 3362-2017;

[0055] Specific surface area and pore volume were determined by nitrogen adsorption / desorption testing of activated carbon fibers using a JW-BK222 fully automated physical adsorption analyzer. Before testing, the samples were degassed under vacuum at 250℃ for 2-3 hours to remove gases and impurities from the pores. Using nitrogen as the adsorbate, the amount of nitrogen adsorbed was measured at 77K within a relative pressure range (P / P0) of 0-1, yielding the adsorption / desorption isotherm of the activated carbon fibers. Based on this isotherm, the specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method. The total pore volume (Vtot) was determined using the amount of N2 adsorbed when the relative pressure was close to 1 (P / P0 = 0.99).

[0056] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0057] Example 1

[0058] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0059] (S1) Polyacrylonitrile fibers were prepared by wet spinning of a DMSO / polyacrylonitrile (PAN) spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot drawing process was carried out in hot water at 94℃.

[0060] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 1mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 15 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0061] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 0.2g / ml for acid activation for 5h.

[0062] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0063] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0064] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 1121 m². 2 / g, the total pore volume is 0.58ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 4mg / g.

[0065] Example 2

[0066] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0067] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0068] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.02, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 15 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0069] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 0.2g / ml for acid activation for 5h.

[0070] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0071] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0072] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 1201 m². 2 / g, the total pore volume is 0.59ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 8mg / g.

[0073] Example 3

[0074] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0075] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0076] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0077] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 0.2g / ml for acid activation for 5h.

[0078] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0079] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0080] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 1385 m². 2 / g, the total pore volume is 0.61ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 13mg / g.

[0081] Example 4

[0082] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0083] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0084] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0085] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 1.0g / ml for acid activation for 5h.

[0086] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0087] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0088] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 1489 m². 2 / g, the total pore volume is 0.63ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 16mg / g.

[0089] Example 5

[0090] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0091] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0092] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0093] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 2.0g / ml for acid activation for 5h.

[0094] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0095] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0096] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 1409 m². 2 / g, with a total pore volume of 0.62ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 15mg / g.

[0097] Example 6

[0098] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0099] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0100] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0101] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 8 hours.

[0102] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0103] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0104] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2084 m². 2 / g, the total pore volume is 0.72ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 31mg / g.

[0105] Example 7

[0106] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0107] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0108] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0109] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 16h.

[0110] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 60°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0111] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0112] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2753 m². 2 / g, the total pore volume is 0.83ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 49mg / g.

[0113] Example 8

[0114] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0115] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0116] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0117] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 16h.

[0118] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 130°C, introduce CO2 into the reactor until the pressure reaches 10 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0119] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0120] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2731 m². 2 / g, the total pore volume is 0.83ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 48mg / g.

[0121] Example 9

[0122] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0123] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0124] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0125] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 16h.

[0126] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 130°C, introduce CO2 into the reactor until the pressure reaches 18 MPa. Remove the air twice. After processing for 20 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0127] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0128] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2798 m². 2 / g, the total pore volume is 0.84ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 53mg / g.

[0129] Example 10

[0130] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0131] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0132] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0133] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 16h.

[0134] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 130°C, introduce CO2 into the reactor until the pressure reaches 18 MPa. Remove the air twice. After processing for 50 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0135] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0136] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2912 m². 2 / g, the total pore volume is 0.85ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 56mg / g.

[0137] Example 11

[0138] This embodiment illustrates the preparation of silver-containing polyacrylonitrile-based activated carbon fibers using the method of the present invention.

[0139] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMF / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0140] (S2) The spun fibers are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, for a total of 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration 2mol / L) are placed in a supercritical carbon dioxide reactor. CO2 is introduced into the reactor at 40℃ until the pressure reaches 10MPa. The air is removed twice. The reactor is treated for 30 minutes with a stirring rate of 500r / min, and then the pressure is slowly released for 2 minutes. The fibers are then removed.

[0141] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 3.0g / ml for acid activation for 16h.

[0142] (S4) Place the activated low-temperature carbon fiber into a supercritical carbon dioxide reactor. At 130°C, introduce CO2 into the reactor until the pressure reaches 18 MPa. Remove the air twice. After processing for 50 minutes, slowly depressurize for 2 minutes and then remove the activated low-temperature carbon fiber.

[0143] (S5) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0144] Silver-containing polyacrylonitrile-based activated carbon fibers were obtained, and the specific surface area of ​​the activated carbon fibers was tested to be 2983 m². 2 / g, the total pore volume is 0.86ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 60mg / g.

[0145] Comparative Example 1

[0146] Silver-containing polyacrylonitrile-based activated carbon fibers were prepared using the same method as in Example 1, except that they were not activated by supercritical carbon dioxide. Specifically:

[0147] (S1) Polyacrylonitrile fibers were prepared by wet spinning of DMSO / polyacrylonitrile spinning solution with a solid content of 11.8%. The spinneret orifice diameter was 0.055 mm and the number of spinneret orifices was 3000. The PAN fibers were passed through a coagulation bath with a coagulation bath temperature and concentration of 0℃ and 12% respectively. The hot stretching process was carried out in hot water at 94℃.

[0148] (S2) The fibers obtained from spinning are pre-oxidized in an oxidation furnace in four temperature zones: 220℃, 235℃, 255℃, and 275℃, respectively, for 45 minutes to prepare pre-oxidized fibers. The pre-oxidized fibers and a mixed solution of silver nitrate / perfluoropolyether phosphate ether (silver nitrate:perfluoropolyether phosphate ether = 1:0.01, silver nitrate concentration is 1mol / L) are placed in a three-necked flask and mechanically stirred at 300r / min for 30min. The mixture is then removed and allowed to air dry for 12 hours.

[0149] (S3) Then the pre-oxidized fiber is carbonized at a low temperature from 300 to 800℃ at a heating rate of 10℃ / min. The carbonized fiber is then immersed in a hydrochloric acid solution with a concentration of 0.2g / ml for acid activation. After immersion for 5 hours, it is dried in an oven to obtain activated low-temperature carbon fiber.

[0150] (S4) After being removed, the fiber is heated at a rate of 30℃ / min under N2 atmosphere protection from room temperature to 1200℃.

[0151] The resulting silver-containing polyacrylonitrile-based activated carbon fibers had a tested specific surface area of ​​875 m². 2 / g, the total pore volume is 0.51ml / g, and the silver loading in the silver-containing polyacrylonitrile-based activated carbon fiber is 2mg / g.

[0152] Test Example 1

[0153] Examples 1-11 and Comparative Example 1 were tested for antibacterial and mechanical properties. Five tests were conducted in parallel for each example and comparative example, and the average value was taken. The results are shown in Table 1.

[0154] Table 1

[0155]

[0156]

[0157] As shown in the table above, the silver loading in the polyacrylonitrile-based activated carbon fibers with deposited silver particles prepared by this invention is greatly improved, resulting in good antibacterial and bacteriostatic effects and enhancing the antibacterial effect.

[0158] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing silver-containing activated carbon fibers with supercritical carbon dioxide assistance, characterized in that, The method includes: (S1) The spinning solution is subjected to spinning and pre-oxidation treatment to obtain pre-oxidized fiber; (S2) Under the first supercritical carbon dioxide condition, the pre-oxidized fiber, silver nitrate solution and surfactant are contacted to obtain silver-containing pre-oxidized fiber; (S3) The silver-containing pre-oxidized fiber is subjected to low-temperature carbonization, acidification and high-temperature carbonization to obtain silver-containing activated carbon fiber.

2. The method according to claim 1, wherein, In step (S2), the first supercritical carbon dioxide conditions include: a temperature of 35-90℃, a pressure of 8-16MPa, and a treatment time of 10-30min; Preferably, the temperature is 40-80℃, the pressure is 10-14MPa, and the treatment time is 15-25min; Preferably, in step (S2), the first supercritical carbon dioxide condition further includes: purging air 2-5 times, with a depressurization time of 1-3 minutes; Preferably, the process is carried out at a stirring rate of 100-500 rpm.

3. The method according to claim 1, wherein, The concentration of the silver nitrate solution is 0.5-2 mol / L, preferably 0.8-1.8 mol / L.

4. The method according to any one of claims 1-3, wherein, The surfactant is selected from one or more of perfluoropolyether phosphate ethers, phosphate salts, and alkylbenzene sulfonates; And / or, the mass ratio of the surfactant to the silver nitrate solution is (0.005-0.02):1, preferably (0.01-0.015):

1.

5. The method according to claim 1, wherein, The spinning solution includes one or more of polyacrylonitrile-based spinning solution, viscose-based spinning solution and pitch-based spinning solution, preferably polyacrylonitrile-based spinning solution; And / or, the spinning solvent in the spinning solution is selected from one or more of N,N-dimethylformamide, dimethyl sulfoxide, and dimethylacetamide.

6. The method according to claim 1, wherein, The conditions for low-temperature carbonization include: a temperature of 300-800℃ and a time of 2-15 minutes; Preferably, the heating rate during the low-temperature carbonization process is 5-10℃ / min; And / or, the acidification treatment conditions include: using phosphoric acid and / or hydrochloric acid, preferably, the concentration of the acid is 0.1-3 g / ml, and the soaking time is 5-18 h; And / or, the conditions for high-temperature carbonization include: high-temperature carbonization for 2-15 minutes at a temperature of 1200-1600°C under inert gas protection; Preferably, the heating rate during the high-temperature carbonization process is 5-30℃ / min.

7. The method according to any one of claims 1-6, wherein, The method further includes: in step (S3), before performing the high-temperature carbonization treatment, subjecting the fiber obtained by the acidification treatment to a second supercritical carbon dioxide active treatment; Preferably, the conditions for the second supercritical carbon dioxide active treatment include: a temperature of 50-140℃, a pressure of 8-20MPa, and a treatment time of 10-50min; Preferably, the temperature is 60-130℃, the pressure is 9-18MPa, and the treatment time is 15-45min.

8. A silver-containing activated carbon fiber prepared by the method according to any one of claims 1-7.

9. The silver-containing activated carbon fiber according to claim 8, wherein, The specific surface area of ​​the silver-containing activated carbon fiber is 1000-3000 m². 2 / g, with a total pore volume of 0.5-0.9 ml / g; Preferably, the silver loading in the silver-containing activated carbon fiber is 3-60 mg / g, and more preferably 4-60 mg / g.

10. The application of the silver-containing activated carbon fiber as described in claim 8 or 9 in water purification.

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