Method for modifying activated carbon fibers and use thereof

Abstract

The application provides a modification method of activated carbon fiber and application thereof, and the preparation method comprises the following steps: performing ultrasonic treatment on polyacrylonitrile-based activated carbon fiber cloth; and performing modification treatment on the polyacrylonitrile-based activated carbon fiber cloth after the ultrasonic treatment, wherein the modification treatment at least comprises one of ultraviolet light treatment and citric acid soaking treatment, so as to obtain an ultraviolet light modified ACF sheet, a citric acid soaking modified ACF sheet or a composite modified ACF sheet. The modification method of activated carbon fiber provided by the application adopts the composite treatment method of citric acid soaking+ultraviolet light treatment after ultrasonic treatment, so that the ACF composite modification treatment is performed, the energy consumption is low, the time is short, the reagent used is citric acid, the environment is friendly, the composite modification condition is more moderate, and the environment is protected.

Description

Technical Field

[0001] This invention relates to the field of carbon fiber material modification technology, and in particular to a method for modifying activated carbon fiber and its application. Background Technology

[0002] With the rapid development of my country's economy, there is a great demand for activated carbon fiber materials in aerospace and civilian applications such as air filters. However, my country lags behind in the technology for preparing high-performance carbon fiber materials, and relies heavily on imports.

[0003] Furthermore, current modification methods for activated carbon fibers primarily involve high-temperature heat treatment to increase the number of oxygen-containing functional groups on the surface. However, due to their poor high-temperature oxidation resistance, inert gas protection is required during high-temperature treatment, which drastically increases the modification cost of activated carbon fibers. In addition, modification methods for activated carbon fibers may also involve immersion and etching with strong acids and alkalis to increase the surface roughness of the fibers; however, these strong acid and alkali reagents can easily cause wastewater discharge problems in industrial production. Summary of the Invention

[0004] Based on this, the purpose of this invention is to propose a method for modifying activated carbon fibers and its application, so as to solve the problems of excessive modification cost or easy generation of waste liquid in existing activated carbon fiber modification methods.

[0005] On one hand, the present invention proposes a method for modifying activated carbon fibers, the preparation method comprising:

[0006] The polyacrylonitrile-based activated carbon fiber cloth was ultrasonically treated.

[0007] The ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth is modified by at least one of ultraviolet light treatment and citric acid immersion treatment to obtain ultraviolet-modified ACF sheets, citric acid-immersion modified ACF sheets, or composite modified ACF sheets.

[0008] In a preferred embodiment of the present invention, the modification treatment of the ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth includes:

[0009] The ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth was placed in a UV analyzer and irradiated with a UV lamp to obtain UV-modified ACF sheets.

[0010] In a preferred embodiment of the present invention, the modification treatment of the ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth includes:

[0011] The ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth was soaked in citric acid solution. After soaking, the polyacrylonitrile-based activated carbon fiber cloth was taken out and washed until neutral. It was then placed in an oven to dry, so as to obtain citric acid-soaked modified ACF sheets.

[0012] In a preferred embodiment of the present invention, the modification treatment of the ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth includes:

[0013] The UV-modified ACF sheet was immersed in citric acid solution. After immersion, the UV-modified ACF sheet was removed and washed until neutral. It was then placed in an oven to dry, thus obtaining the composite modified ACF sheet.

[0014] Alternatively, the citric acid-soaked modified ACF tablets can be placed in a UV analyzer and irradiated with a UV lamp to obtain composite modified ACF tablets.

[0015] In a preferred embodiment of the present invention, the ultrasonic treatment of the polyacrylonitrile-based activated carbon fiber cloth includes:

[0016] Cut the polyacrylonitrile-based activated carbon fiber cloth into pieces, place the cut polyacrylonitrile-based activated carbon fiber cloth into a beaker containing deionized water, and then sonicate the beaker containing the polyacrylonitrile-based activated carbon fiber cloth for 25-35 minutes.

[0017] In a preferred embodiment of the present invention, the concentration of the citric acid solution is 2%-10%.

[0018] In a preferred embodiment of the present invention, the ultraviolet light wavelength of the ultraviolet lamp is 254-365nm, and the ultraviolet irradiation time is 1-5h.

[0019] In a preferred embodiment of the present invention, the drying temperature of the oven is 100-140℃ and the drying time is 2-3 hours.

[0020] In a preferred embodiment of the present invention, the formula for calculating the SO2 absorption content of the prepared UV-modified ACF sheet, citric acid-impregnated modified ACF sheet, or composite modified ACF sheet is as follows:

[0021]

[0022] Where K represents the SO2 content adsorbed by the activated carbon fiber, mg / g; C0 represents the concentration of injected SO2, mg / ml; V nd The volume of SO2 injected is represented in ml; C(1 / 2I2) represents the concentration of the iodine standard solution in mol / L; V1 represents the volume of iodine standard solution consumed by the remaining SO2 after adsorption by the activated carbon fiber in ml; 32.0 is the mass of sulfur dioxide equivalent to 1 ml of 1 mol / L iodine standard solution in mg; m ACFThe mass of activated carbon fiber is expressed in grams (g).

[0023] On the other hand, the present invention also provides the application of activated carbon fibers obtained by a method for modifying activated carbon fibers in SO2 adsorption.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] 1. Ultraviolet light treatment has low energy consumption, and ultraviolet analyzers are very inexpensive and durable compared to instruments used in other modification methods.

[0026] 2. UV modification requires a short time, and UV light treatment is simple to operate, does not require highly skilled operators, and does not involve any danger to the human body.

[0027] 3. Citric acid is a commonly used organic acid that is harmless to the human body, environmentally friendly, and easily decomposed. After simple treatment, it can be directly discharged. Traditional soaking reagents are mostly strong oxidants, strong acids, and strong alkalis, which can easily cause waste liquid discharge problems in large-scale industrial production, which is detrimental to environmental protection.

[0028] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments of the invention. Attached Figure Description

[0029] Figure 1 Adsorption capacity of ACF-SO2 after UV light modification at different wavelengths;

[0030] Figure 2 Figure 1 shows the adsorption capacity of modified ACF-SO2 after soaking in citric acid of different concentrations.

[0031] Figure 3 This is a graph showing the adsorption capacity of ACF-SO2 under combined treatment.

[0032] Figure 4 FT-IR spectra of ACF materials prepared by different modification methods.

[0033] The following detailed description, in conjunction with the accompanying drawings, will further illustrate the present invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Several embodiments of the invention are illustrated in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] Examples 1-5

[0037] The polyacrylonitrile activated carbon fiber cloth (hereinafter referred to as ACF) was cut into pieces of 7.5cm*3cm, approximately 1g per piece. The cut ACF was then placed in a beaker containing 250ml of deionized water, and the beaker was placed in an ultrasonic cleaner for ultrasonic treatment for 30 minutes. Finally, the ACF pieces were placed in an oven and dried at 120℃ for 2 hours.

[0038] The ultrasonically treated ACF sheets were placed in a UV analyzer and irradiated with a 365nm UV lamp for 1h, 2h, 3h, 4h, and 5h, respectively, to obtain five ACF sheets modified by 365nm UV light treatment for different times. The prepared UV-modified ACF sheets were then subjected to SO2 adsorption tests.

[0039] Examples 6-10

[0040] The polyacrylonitrile activated carbon fiber cloth (hereinafter referred to as ACF) was cut into pieces of 7.5cm*3cm, approximately 1g / piece. The cut ACF was then placed in a beaker containing 250ml of deionized water, and the beaker was placed in an ultrasonic cleaner for ultrasonic treatment for 30 minutes. The ACF pieces were then placed in an oven at 120℃ for 2 hours to dry.

[0041] The ultrasonically treated ACF sheets were placed in a UV analyzer and irradiated with a 254nm UV lamp for 1h, 2h, 3h, 4h, and 5h, respectively, to obtain five ACF sheets modified by 254nm UV light treatment for different times. The prepared UV-modified ACF sheets were then subjected to SO2 adsorption tests.

[0042] Examples 11-15

[0043] The polyacrylonitrile activated carbon fiber cloth (hereinafter referred to as ACF) was cut into pieces of 7.5cm*3cm, approximately 1g / piece. The cut ACF was then placed in a beaker containing 250ml of deionized water, and the beaker was placed in an ultrasonic cleaner for ultrasonic treatment for 30 minutes. The ACF pieces were then placed in an oven at 120℃ for 2 hours to dry.

[0044] Five pieces of ACF (acetic acid fluoride) after ultrasonic treatment were immersed in 2%, 4%, 6%, 8%, and 10% citric acid solutions for 24 hours, respectively. Afterward, they were removed, washed with water until neutral, and then dried in an oven at 120℃ for 3 hours. They were then treated with 254nm UV light for 3 hours to obtain citric acid + UV modified ACF. The five pieces of composite modified ACF were then subjected to SO2 adsorption tests.

[0045] Examples 16-20

[0046] The polyacrylonitrile activated carbon fiber cloth (hereinafter referred to as ACF) was cut into pieces of 7.5cm*3cm, approximately 1g / piece. The cut ACF was then placed in a beaker containing 250ml of deionized water, and the beaker was placed in an ultrasonic cleaner for ultrasonic treatment for 30 minutes. The ACF pieces were then placed in an oven at 120℃ for 2 hours to dry.

[0047] Five pieces of ACF (acoustic fluoride) after ultrasonic treatment were placed in a UV analyzer and treated with 254nm UV light for 3 hours. Then, they were immersed in 2%, 4%, 6%, 8%, and 10% citric acid solutions, respectively, for 24 hours. Afterward, they were removed, washed with water until neutral, and dried in an oven at 120℃ for 3 hours. This yielded UV-modified ACF with citric acid immersion. The five pieces of composite modified ACF were then subjected to SO2 adsorption tests.

[0048] Comparative Example

[0049] The comparison example is a standard activated carbon fiber cloth (raw sheet) that has not undergone any of the following treatments: ultrasonic treatment, ultraviolet light treatment, or citric acid soaking.

[0050] Please refer to Table 1 below, which shows the SO2 adsorption capacity of ACF after ultrasonic treatment and modification with ultraviolet light at different wavelengths. As seen in the 365nm treatment, initially, the ACF-SO2 adsorption capacity gradually increased with the duration of ultraviolet light treatment, reaching its peak at 2 hours with an adsorption capacity of 6.012 mg / g, representing a 24.32% increase in adsorption rate. However, with further ultraviolet light exposure, the ACF-SO2 adsorption capacity began to decrease; even after 5 hours of 365nm ultraviolet light treatment, the adsorption rate actually decreased by 10.64%.

[0051] After treatment with 254nm ultraviolet light, the adsorption capacity of ACF-SO2 initially increased with the duration of irradiation. It reached its maximum at 6.573 mg / g after 3 hours of irradiation at 254nm, representing an increase of 35.91%. Therefore, we chose 254nm ultraviolet light treatment for 3 hours for subsequent composite modification.

[0052] Table 1. Adsorption capacity of ACF-SO2 after UV modification treatment at different wavelengths

[0053]

[0054] Please see Figure 1 The graph shows the adsorption capacity of ACF-SO2 after modification with different wavelengths of ultraviolet light. Figure 1 It is evident that after UV treatment, the adsorption capacity of ACF-SO2 is significantly increased compared to the original substrate. However, when exposed to UV light for an extended period, ACF exhibits noticeable aging, leading to a significant decrease in the material's SO2 adsorption capacity, even falling below that of the original substrate. Treatment with 254nm UV light for 3 hours demonstrates the best modification effect.

[0055] Please refer to Table 2 below, which shows the SO2 adsorption capacity of ACF after ultrasonic treatment and immersion in citric acid of different concentrations. As can be seen from the table, the SO2 adsorption capacity of ACF is significantly increased after immersion in citric acid. ACF immersed in 4% citric acid showed the highest SO2 adsorption capacity, reaching 6.583 mg / g, with an adsorption rate increase of 36.12%.

[0056] Table 2. Adsorption capacity of modified ACF-SO2 after soaking in citric acid of different concentrations

[0057]

[0058] Please see Figure 2 The graph shows the adsorption capacity of modified ACF-SO2 after soaking in different concentrations of citric acid. Figure 2 It can also be clearly seen that after soaking in citric acid, the overall ACF-SO2 adsorption capacity is increased compared to the original tablet.

[0059] Please refer to Table 3 below for the adsorption data of ACF-SO2 after different composite treatments. As can be seen from the table, after ultrasonic treatment, ACF was first soaked in 8% citric acid for 24 hours and then irradiated with 254nm ultraviolet light for 3 hours. The adsorption capacity of SO2 reached 6.936 mg / g, and the adsorption rate was increased by 43.41% compared with the original tablet. Compared with single ultraviolet light treatment and citric acid soaking, it has been further improved, showing a very good composite modification effect.

[0060] After ultrasonic treatment, followed by 3 hours of 254nm ultraviolet light exposure and then citric acid immersion treatment, the optimal modified ACF-SO2 adsorption capacity was 6.465 mg / g, with an adsorption rate increase of 33.67%. However, the modification effect was not as good as that of single ultraviolet light modification and citric acid immersion modification.

[0061] Table 3. ACF-SO2 adsorption capacity after different composite treatments (UV treatment at 254 nm for 3 h)

[0062]

[0063]

[0064] Please see Figure 3 The graph shows the adsorption capacity of ACF-SO2 under combined treatment. Figure 3 As can be seen, the adsorption capacity of ACF-SO2 is improved after composite modification treatment. However, after sonication, ACF soaked in 8% citric acid for 24 hours and then irradiated with 254nm ultraviolet light for 3 hours has the largest adsorption capacity for SO2.

[0065] Please see Figure 4 The images show the FT-IR spectra of ACF materials prepared by different modification methods. Figure 4 As can be seen, after being soaked in citric acid, ACF at 1740-1650 cm⁻¹ -1 A more pronounced dimer absorption peak appeared, which is the C=O stretching vibration peak of —COOH; and it is located in the 3300-3500 cm⁻¹ range. -1 A more pronounced absorption peak also appeared at the 1300 cm⁻¹, which is the —OH stretching vibration peak, indicating that more oxygen-containing functional groups such as carboxyl groups were generated on the surface of the original ACF sheet after soaking in citric acid. After irradiation with 254 nm UV light, the C=O stretching vibration peak of —COOH and the —OH stretching vibration peak were clearly weakened, indicating that the oxygen-containing functional groups of ACF decreased under UV irradiation. After ultrasonication, ACF was first soaked in 8% citric acid and then irradiated with 254 nm UV light for 3 hours for composite modification treatment. It can be seen that the ACF surface still retains abundant oxygen-containing functional groups, and compared with the original sheet and ACF modified by a single treatment, its oxygen-containing functional groups at 1300 cm⁻¹ are significantly higher. -1 There is a distinct absorption peak on the left and right sides, which is the C-O-C stretching vibration peak of the ester group. This indicates that after the composite treatment, the oxygen-containing functional groups on the surface of the ACF material are more abundant and complex, thus further enhancing its adsorption capacity for SO2.

[0066] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0067] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for modifying activated carbon fibers, characterized in that, The modification method includes: After cutting the polyacrylonitrile-based activated carbon fiber cloth, place it in a beaker containing deionized water and sonicate it for 25-35 minutes. After sonication, dry it at 100-140℃ for 2-3 hours. The ultrasonically treated polyacrylonitrile-based activated carbon fiber cloth was subjected to composite modification treatment. The composite modification treatment was as follows: first, it was soaked in an 8% citric acid solution for 24 hours, then taken out and washed until neutral, and then placed in an ultraviolet analyzer and irradiated with an ultraviolet lamp with a wavelength of 254nm for 3 hours to obtain composite modified activated carbon fiber sheets. The composite modified activated carbon fiber sheet has an adsorption capacity of ≥6.93 mg / g for SO2, which is ≥43% higher than that of activated carbon fiber without ultrasonic treatment and composite modification treatment.

2. The method for modifying activated carbon fiber according to claim 1, characterized in that, The ultrasonic treatment time is 30 minutes.

3. The method for modifying activated carbon fiber according to claim 1, characterized in that, After ultrasonication, dry at 120℃ for 2 hours.

4. The method for modifying activated carbon fiber according to claim 1, characterized in that, The prepared composite modified activated carbon fiber sheet contains carboxyl, hydroxyl, and ester functional groups on its surface, with the characteristic absorption peak of the ester group located at 1300 cm⁻¹. -1 .

5. The method for modifying activated carbon fiber according to claim 1, characterized in that, The formula for calculating the SO2 absorption content of the prepared composite modified activated carbon fiber sheets is as follows: Where K represents the SO2 content adsorbed by the activated carbon fiber, mg / g; C0 represents the concentration of injected SO2, mg / ml; V nd The volume of SO2 injected is represented in ml; C(1 / 2I2) represents the concentration of the iodine standard solution in mol / L; V1 represents the volume of iodine standard solution consumed by the remaining SO2 after adsorption by the activated carbon fiber in ml; 32.0 is the mass of sulfur dioxide equivalent to 1 ml of 1 mol / L iodine standard solution in mg; m ACF The mass of activated carbon fiber is expressed in grams (g).

6. The application of activated carbon fiber obtained by the modification method of activated carbon fiber according to claim 1 in SO2 adsorption.

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