An Ag / TiO2 / GO-doped PAN photocatalytic film, its preparation method and application

Abstract

This invention belongs to the field of photocatalytic materials, specifically relating to an Ag / TiO2 / GO-doped PAN photocatalytic film, its preparation method, and its applications. This invention utilizes a one-step method to prepare the Ag / TiO2 / GO composite material, subsequently adding Ag / TiO2 / GO to PAN, and then preparing the Ag / TiO2 / GO-PAN photocatalytic film via electrospinning. The thin film material prepared by this invention can be applied in fields such as air purification, wastewater treatment, and antibacterial clothing, exhibiting high catalytic activity and good stability.

Description

Technical Field

[0001] This invention belongs to the field of catalytic membrane technology, specifically relating to an Ag / TiO2 / GO doped PAN photocatalytic membrane, its preparation method, and its application. Background Technology

[0002] As the contradiction between humanity's ever-increasing energy demand and growing energy shortage intensifies, the development and utilization of new energy sources, especially solar energy, has become increasingly important. Photocatalysis, with its advantages of mild reaction conditions and the ability to directly convert solar energy into chemical energy, has attracted much attention from researchers.

[0003] Photocatalysis technology refers to the process by which a photocatalyst absorbs light energy under external light radiation, generating conduction band electrons and valence band holes, which are then adsorbed onto the catalyst surface and undergo a chemical reaction. The photocatalytic process of a PAN film involves the following steps: The PAN film serves as the substrate, supporting the photocatalytic material. When light reaches the TiO2-PAN film, the photocatalytic material absorbs light energy, generating excited-state electrons and holes. Under the influence of light absorption, these excited-state electrons and holes react to produce reactive oxygen species, such as hydroxyl radicals (·OH) and superoxide radicals (·O). 2- These reactive oxygen species (ROS) possess strong oxidizing capabilities and can react with organic pollutants, bacteria, and other microorganisms. For example, hydroxyl radicals can decompose organic pollutants into smaller, harmless substances through oxidation. Superoxide radicals can react with bacterial cell walls and other structures, destroying their structure and thus achieving a bactericidal effect. After the photocatalytic reaction, the reaction products are released into the environment. Depending on the reactants and reaction conditions, the reaction products can be harmless substances such as water and carbon dioxide.

[0004] PAN photocatalytic membranes have a wide range of applications and offer advantages such as broad wavelength response, reusability, and strong controllability. However, their photocatalytic efficiency is relatively low, requiring extended illumination times to achieve effective degradation or sterilization. This is primarily due to the low activity and poor light absorption efficiency of the photocatalytic material. Furthermore, the photocatalytic material in PAN membranes is prone to photocorrosion and structural damage under prolonged illumination, leading to a decline in photocatalytic performance. This limits the long-term stability and durability of the photocatalytic membrane.

[0005] In existing technologies, combining PAN with other semiconductor materials (such as TiO2, ZnO, CdS, etc.) to form heterojunctions can promote the effective separation of electron-hole pairs, reduce the recombination probability of charge carriers, and improve photocatalytic performance. However, there are problems such as complex preparation process, high cost, and poor interface matching between different materials, which may lead to poor contact and affect charge transfer efficiency.

[0006] Therefore, it is of paramount importance to develop a method that is both efficient and stable. Summary of the Invention

[0007] The purpose of this invention is to provide an Ag / TiO2 / GO-doped PAN photocatalytic film, its preparation method, and its applications. This invention prepares an Ag / TiO2 / GO composite material with excellent photocatalytic performance and adds it to a PAN film, which can greatly improve the film's light absorption capacity, catalytic performance, and antifouling ability.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for preparing an Ag / TiO2 / GO-doped PAN photocatalytic film includes the following steps:

[0010] (1) Mix modified graphene oxide powder, tetrabutyl titanate, and silver nitrate in a mass ratio of 1:(1-5):1, and add them to a water / ethanol mixture. Stir until homogeneous to obtain a mixed solution. Add the mixed solution to a sealed container and heat to 80-120℃ for 1-3 hours. After the reaction is complete, cool to room temperature, centrifuge, wash, and freeze-dry to obtain Ag / TiO2 / GO composite material. The modified graphene oxide powder includes chitosan modified graphene oxide powder and amino modified graphene oxide powder in a mass ratio of (2-3):1.

[0011] (2) Add Ag / TiO2 / GO composite material and PAN in a mass ratio of 1:(5-15) to N,N-dimethylformamide, stir magnetically at 45-60℃ for 30-120 min until completely dissolved, and then let stand at 32-35℃ to remove bubbles to obtain spinning solution.

[0012] (3) Add the spinning solution into the syringe, fix the syringe on the micro-injection pump, connect the needle of the injection pump to the positive terminal of the high voltage power supply, and connect the negative terminal to the receiving roller; control the electrospinning positive voltage to 15-18kV, the negative voltage to -1.5kV, the distance from the receiving roller to the needle to 5-15cm, and the spinning solution flow rate to 0.5-1.5mL / h to perform electrospinning and obtain Ag / TiO2 / GO doped PAN photocatalytic film.

[0013] Furthermore, the preparation method of the chitosan-modified graphene oxide powder includes the following steps:

[0014] (1) Disperse 1 part by mass of graphene oxide powder A in 10-15 parts by mass of deionized water, ultrasonically disperse for 1-3 hours, add 0.04-0.07 parts by mass of silane coupling agent KH550, reflux at 40-45℃ for 3-5 hours, centrifuge to obtain silane-modified graphene oxide powder.

[0015] (2) Disperse the silane-modified graphene oxide powder prepared in step (1) in 10-15 parts by mass of methanol, ultrasonically disperse for 1-3 hours, add 0.06-0.08 parts by mass of glutaraldehyde in a water bath at 40-45℃, add 0.01-0.015 parts by mass of acetic acid dropwise, and reflux for 3-5 hours; add dilute nitric acid solution of chitosan, and continue to reflux for 3-6 hours at 40-45℃. After the reaction is completed, centrifuge to obtain chitosan-modified graphene oxide powder.

[0016] Commercially available graphene oxide (GO) is prone to agglomeration, affecting the loading effect of titanium dioxide and silver. This invention improves the photocatalytic degradation activity of the photocatalytic membrane by modifying GO with chitosan. Chitosan can form a protective film on the GO surface, preventing GO sheets from agglomerating and maintaining its dispersibility and large specific surface area. This helps expose more active sites to participate in the photocatalytic reaction. Chitosan molecules contain a large number of amino and hydroxyl groups. These functional groups can not only serve as adsorption sites to immobilize organic pollutants, but also interact with photogenerated holes or electrons to generate more reactive oxygen species (ROS), such as hydroxyl radicals (·OH) and superoxide anion radicals (·O2). - These active species can more effectively degrade organic pollutants and improve photocatalytic degradation efficiency. Chitosan, as a natural polymer, has good film-forming properties and mechanical strength. It can help PAN fibers form a denser and more uniform network structure, improving the overall stability and durability of the photocatalytic membrane. This means that the photocatalytic membrane is not easily damaged or deactivated during long-term use and can maintain high catalytic activity. Chitosan-modified GO works together with Ag and TiO2 to form a multi-component synergistic system. Ag nanoparticles can act as electron traps to further promote charge separation; TiO2 provides efficient photocatalytic activity; while chitosan-modified GO enhances the stability and light absorption capacity of the material. This synergistic effect comprehensively improves the performance of the entire photocatalytic membrane.

[0017] Furthermore, the mass ratio of the graphene oxide powder A to chitosan is 1:(0.2-0.3).

[0018] Furthermore, the concentration of dilute nitric acid is 0.1-0.15 mol / L. The mass ratio of chitosan to dilute nitric acid is 1:(3-5).

[0019] Furthermore, the size of graphene oxide powder A is 1–3 μm; the number of layers is 1–3.

[0020] Furthermore, the preparation method of the amino-modified graphene oxide powder includes the following steps:

[0021] (1) Add graphene oxide powder B to deionized water and ultrasonically disperse at 0-5℃ for 30-40 min to obtain graphene oxide dispersion, wherein the concentration of graphene oxide is 0.1-0.2 g / L;

[0022] (2) Add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide to the graphene oxide dispersion, stir magnetically in an ice bath to obtain a mixed solution; continue to add ethylenediamine, react for 13-15 h, wash the product thoroughly with acetone / deionized water, dry it to obtain amino-modified graphene oxide powder.

[0023] To improve the water-oil separation performance of photocatalytic membranes, this invention adds amino-modified graphene oxide to the system and blends it with chitosan-modified graphene oxide powder in a specific ratio. The two work synergistically to improve the water-oil separation performance of the photocatalytic membrane, especially demonstrating excellent separation effects on water-in-hexane emulsions. By blending chitosan-modified graphene oxide (CS-GO) and amino-modified graphene oxide (NH2-GO) in a specific ratio, the hydrophilic effect in the photocatalytic membrane can be improved, significantly enhancing its water-oil separation performance, particularly exhibiting excellent separation effects on water-in-hexane emulsions.

[0024] Furthermore, the amount of ethylenediamine added is 2-7% of the volume of the mixed solution.

[0025] Furthermore, the amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide added is 20-30% of the mass of graphene oxide.

[0026] Furthermore, the amount of N-hydroxysuccinimide added is 20-30% of the mass of graphene oxide.

[0027] Furthermore, the size of the graphene oxide powder B is 1–3 μm; the number of layers is 1–3.

[0028] Furthermore, the ratio of the total mass of the mixed modified graphene oxide powder, tetrabutyl titanate, and silver nitrate to the mass of the water and ethanol mixture is 1:(7-10).

[0029] Furthermore, the mass ratio of water to ethanol in the water / ethanol mixture is 1:(1-5).

[0030] Furthermore, the total mass ratio of Ag / TiO2 / GO composite material and PAN to N,N-dimethylformamide is 1:(8-12).

[0031] This invention provides an Ag / TiO2 / GO-doped PAN photocatalytic film prepared by the aforementioned method.

[0032] The third aspect of the present invention provides the application of the Ag / TiO2 / GO-doped PAN photocatalytic membrane in air purification, wastewater treatment, and antibacterial clothing.

[0033] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0034] 1. To address the relatively low photocatalytic efficiency of TiO2-PAN photocatalytic films and the problems of photocorrosion and structural damage of TiO2 under prolonged light irradiation, this invention prepares a catalytic material with excellent catalytic performance and superior compatibility, Ag / TiO2 / GO, using a one-step method. Subsequently, Ag / TiO2 / GO is added to PAN, and Ag / TiO2 / GO-PAN photocatalytic films are prepared by electrospinning. This invention utilizes electrospinning to spin PAN spinning solutions containing the desired components; the steps are simple and the method is practical.

[0035] 2. This invention utilizes the characteristics of GO nanosheets—large specific surface area, high electron mobility, and numerous active sites—to load TiO2 and Ag onto GO using a simple solution method, resulting in a high-performance catalyst. TiO2 exhibits high chemical stability, is non-toxic, and possesses excellent photocatalytic performance, while Ag effectively captures photogenerated electrons generated in the system and possesses the unique surface plasmon resonance effect of noble metals. Subsequently, the Ag / TiO2 / GO mixture is loaded onto PAN to obtain an Ag / TiO2 / GO-PAN photocatalytic film. This not only significantly improves the photocatalytic activity of the film but also extends its light absorption range into the visible light region, substantially enhancing light utilization.

[0036] 3. The present invention provides a simple and low-cost method for preparing PAN photocatalytic membranes via electrospinning. By loading TiO2 and Ag onto GO, a novel high-efficiency photocatalyst, Ag / TiO2 / GO, is prepared. This catalyst has good compatibility with PAN and can effectively solve the problem of uneven distribution of TiO2 catalyst in the PAN matrix. In addition, this catalyst can enhance the light absorption capacity of the PAN membrane, promote the separation of electrons and holes, accelerate electron transport, and improve anti-fouling performance, thereby improving the stability of the photocatalytic performance of the PAN membrane.

[0037] 4. By modifying graphene oxide with chitosan, this invention can improve the photocatalytic degradation activity and stability of the photocatalytic membrane.

[0038] 5. In this invention, amino-modified graphene oxide is added to the system and compounded with chitosan-modified graphene oxide powder in a specific ratio. The two have a synergistic effect, which can improve the water-oil separation performance of the photocatalytic membrane, especially the excellent separation effect on water-in-hexane emulsion. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the preparation process of Ag / TiO2 / GO-PAN photocatalytic membrane.

[0040] Figure 2 SEM images of TiO2-PAN film (a) and Ag / TiO2 / GO-PAN film (b).

[0041] Figure 3 This is a schematic diagram showing the methyl orange decolorization rate of TiO2-PAN membrane and Ag / TiO2 / GO-PAN membrane. Detailed Implementation

[0042] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] All raw materials used in this invention are commercially available products:

[0044] PAN: Polyacrylonitrile powder, Hubei Kemaidi Chemical Co., Ltd., molecular weight 90,000.

[0045] 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), CAS No.: 25952-53-8.

[0046] N-hydroxysuccinimide (NHS), CAS No.: 5576-84-8.

[0047] Example 1

[0048] like Figure 1 As shown, this embodiment provides an Ag / TiO2 / GO-doped PAN photocatalytic film, the preparation method of which includes the following steps:

[0049] (1) A mixture of modified graphene oxide powder, tetrabutyl titanate, and silver nitrate in a mass ratio of 1:2:1 was added to a water / ethanol mixture and stirred until homogeneous to obtain a mixed solution. The mixed solution was then placed in a sealed container and heated to 100°C for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, centrifuged, washed, and freeze-dried to obtain the Ag / TiO2 / GO composite material. The modified graphene oxide powder consisted of chitosan-modified graphene oxide powder and amino-modified graphene oxide powder in a mass ratio of 2.4:1. The mass ratio of the total mass of the modified graphene oxide powder, tetrabutyl titanate, and silver nitrate to the mass of the water and ethanol mixture was 1:8. The mass ratio of water to ethanol in the water / ethanol mixture was 1:3.

[0050] (2) Add Ag / TiO2 / GO composite material and PAN in a mass ratio of 1:10 to N,N-dimethylformamide, stir magnetically at 50°C for 60 min until completely dissolved, and then let stand at 35°C to remove bubbles to obtain spinning solution; the total mass of Ag / TiO2 / GO composite material and PAN: the mass ratio of N,N-dimethylformamide is 1:10.

[0051] (3) Add the spinning solution into the syringe, fix the syringe on the micro-injection pump, connect the needle of the injection pump to the positive terminal of the high voltage power supply, and connect the negative terminal to the receiving roller; control the electrospinning positive voltage to 16kV, the negative voltage to -1.5kV, the distance from the receiving roller to the needle to 10cm, and the spinning solution flow rate to 1mL / h to perform electrospinning and obtain the Ag / TiO2 / GO doped PAN photocatalytic film.

[0052] The preparation method of the chitosan-modified graphene oxide powder includes the following steps:

[0053] (1) Disperse 1 part by mass of graphene oxide powder A in 12 parts by mass of deionized water, ultrasonically disperse for 2 hours, add 0.05 parts by mass of silane coupling agent KH550, reflux at 42°C for 4 hours, and centrifuge to obtain silane-modified graphene oxide powder; the size of graphene oxide powder A is 1 to 3 μm; the number of layers is 1 to 3.

[0054] (2) The silane-modified graphene oxide powder prepared in step (1) was dispersed in 12 parts by mass of methanol and ultrasonically dispersed for 2 hours. Then, under a water bath at 42°C, 0.07 parts by mass of glutaraldehyde was added, followed by dropwise addition of 0.012 parts by mass of acetic acid. The mixture was refluxed for 4 hours. A dilute nitric acid solution of chitosan was added, with a concentration of 0.12 mol / L. The mass ratio of chitosan to dilute nitric acid was 1:4. The mass ratio of graphene oxide powder A to chitosan was 1:0.25. The mixture was refluxed at 42°C for another 5 hours. After the reaction was completed, the mixture was centrifuged to obtain chitosan-modified graphene oxide powder.

[0055] The preparation method of the amino-modified graphene oxide powder includes the following steps:

[0056] (1) Add graphene oxide powder B to deionized water and ultrasonically disperse at 5°C for 35 min to obtain graphene oxide dispersion. The concentration of graphene oxide is 0.15 g / L. The size of graphene oxide powder B is 1 to 3 μm. The number of layers is 1 to 3.

[0057] (2) 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide were added to the graphene oxide dispersion and magnetically stirred in an ice bath to obtain a mixed solution; ethylenediamine was added, the amount of ethylenediamine added was 5% of the volume of the mixed solution; the reaction was carried out for 14 hours, the product was thoroughly washed with acetone / deionized water and dried to obtain amino-modified graphene oxide powder.

[0058] The amount of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide added is 25% of the mass of graphene oxide. The amount of N-hydroxysuccinimide added is 25% of the mass of graphene oxide.

[0059] Comparative Example 1

[0060] This comparative example provides a photocatalytic membrane, the preparation method of which includes the following steps:

[0061] (1) Weigh 1 part by mass of TiO2 (particle size 100-200nm) and 10 parts by mass of PAN respectively, then add the two powders to 100 parts by mass of DMF, stir magnetically at 60℃ for 80min until completely dissolved, and then let stand at 35℃ to remove bubbles to obtain spinning solution.

[0062] (2) Add the spinning solution into the syringe, fix the syringe on the micro-injection pump, connect the needle of the injection pump to the positive terminal of the high voltage power supply, and connect the negative terminal to the receiving roller; control the electrospinning positive voltage to 16kV, the negative voltage to -1.5kV, the distance from the receiving roller to the needle to 10cm, and the spinning solution flow rate to 1mL / h to perform electrospinning and obtain the Ag / TiO2 / GO doped PAN photocatalytic film.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that the mixed modified graphene oxide powder is replaced with graphene oxide powder, the size of which is 1-3 μm and the number of layers is 1-3.

[0065] Comparative Example 3

[0066] The difference between this comparative example and Example 1 is that the mixed modified graphene oxide powder is replaced with chitosan modified graphene oxide powder, and the preparation method of the chitosan modified graphene oxide powder is the same as in Example 1.

[0067] Comparative Example 4

[0068] The difference between this comparative example and Example 1 is that the mixed modified graphene oxide powder is replaced with amino modified graphene oxide powder; the preparation method of the amino modified graphene oxide powder is the same as in Example 1.

[0069] Comparative Example 5

[0070] The difference between this comparative example and Example 1 is that the mixed modified graphene oxide powder includes chitosan modified graphene oxide powder and amino modified graphene oxide powder in a mass ratio of 1:2.5.

[0071] Performance testing

[0072] (1) SEM scanning electron microscopy test: A piece of the photocatalytic membrane prepared in Example 1 and Comparative Example 1 was cut out to make a sample, and its morphological characteristics were observed under a scanning electron microscope.

[0073] Tested by SEM (Scanning Electron Microscopy) Figure 2 It was found that the surface of the photocatalytic membrane in Comparative Example 1 was relatively smooth, while the surface of the photocatalytic membrane in Example 1 had more protrusions than the original membrane, indicating that Ag / TiO2 / GO components were indeed introduced into the photocatalytic membrane in Example 1.

[0074] (2) Photocatalytic test: 10 mL of 100 mg / L methyl orange was added to 90 mL of distilled water to prepare a 10 mg / L methyl orange solution. The solution was stirred until homogeneous. Then, the photocatalytic membranes prepared in Example 1 and Comparative Example 1 were fixed with iron wire and immersed in the solution. The solution was stirred in the dark for 1 hour, and a certain amount of solution was taken every 1 hour for absorbance testing. Next, 5 mg of PMS was weighed and added to the solution. The solution was stirred under xenon lamp irradiation, and a certain amount of solution was taken every 10 minutes for absorbance testing and recording. The degradation rate η was calculated according to the formula η = (C0 - C t / C0)×100%=(A0-A t Calculated as (C0) × 100%, where C0 is the concentration before degradation and Ct is the concentration after degradation.

[0075] To test the recyclability of the sample, five cycles were conducted, and the cycle stability of the catalyst was characterized by comparing the photocatalytic degradation curves. Since the material is relatively easy to recover, after each cycle, the material was directly removed from the solution, washed three times with distilled water and ethanol, and then dried in an oven for future use.

[0076] pass Figure 3 It can be seen that the photocatalytic performance of Example 1 was significantly improved. The photocatalytic performance of the membrane was greatly enhanced due to the loading of GO material.

[0077] (3) Quantitative analysis of the photocatalytic degradation performance of tetracycline hydrochloride using a UV-Vis spectrophotometer: A 300W Xe lamp was used as the irradiation source. 50 mg of the photocatalytic membranes prepared in Example 1 and Comparative Examples 1-5 were placed in 50 mL of tetracycline hydrochloride aqueous solution, respectively. The solutions were stirred in the dark for 1 h to reach the adsorption-desorption equilibrium of the catalyst. Samples were taken every 30 min during this period. The solutions were then irradiated with visible light (300W Xe lamp), and samples were taken every 20 min. The analysis was performed using a UV-Vis spectrophotometer (ULTRA plus). The degradation rate of tetracycline hydrochloride within 240 min was calculated as follows: Degradation rate = (C0 - Ct / C0) × 100%, where C0 is the concentration before degradation and Ct is the concentration after degradation.

[0078] (4) Stability: The photocatalytic membranes prepared in Example 1 and Comparative Examples 1-5 were subjected to 20 degradation cycles. The degradation rate of tetracycline hydrochloride in the 20th cycle within 240 min was calculated.

[0079] (5) Oil-water separation: The organic carbon content of the solution before and after separation was analyzed using a total organic carbon analyzer. The water-in-hexane emulsion was tested separately. 20 mL of the water-in-oil emulsion was passed through the circular photocatalytic membrane prepared in Example 1 and Comparative Examples 1-5 with a diameter of 2 cm. The organic carbon content of the solution before and after filtration was measured. The oil-water separation efficiency was calculated as (organic carbon content in the solution before filtration - organic carbon content in the solution after filtration) / organic carbon content in the solution before filtration × 100%.

[0080] The results are shown in Table 1.

[0081] Table 1 Performance Test Results

[0082]

[0083] As can be seen from the above performance test results, Example 1 has good photodegradation effect, high stability, and good water-oil separation effect, making it a product with excellent overall performance.

[0084] The comparative examples, however, did not employ the necessary technical solutions, resulting in significantly inferior performance compared to the examples. The photocatalytic performance of the preparation method in Comparative Example 1 was poor, Comparative Example 2 did not modify the graphene oxide, and the composition and ratio of the mixed modified graphene oxide in Comparative Examples 3-5 were different, leading to a decrease in the photodegradation effect of the photocatalytic film and a deterioration in the water-oil separation effect. These experimental results further demonstrate the importance of the technical solutions defined in this invention for its technical effect.

[0085] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an Ag / TiO2 / GO-doped PAN photocatalytic film, characterized in that, Includes the following steps: (1) Mix the modified graphene oxide powder, tetrabutyl titanate, and silver nitrate in a mass ratio of 1:(1-5):1, and add them to a water / ethanol mixture. Stir until homogeneous to obtain a mixed solution. Add the mixed solution to a sealed container and heat to 80-120℃ for 1-3 hours. After the reaction is complete, cool to room temperature, centrifuge, wash, and freeze-dry to obtain the Ag / TiO2 / GO composite material. The mixed modified graphene oxide powder includes chitosan modified graphene oxide powder and amino modified graphene oxide powder in a mass ratio of (2-3):

1. (2) Add Ag / TiO2 / GO composite material and PAN in a mass ratio of 1:(5-15) to N,N-dimethylformamide, stir magnetically at 45-60℃ for 30-120 min until completely dissolved, and then let stand at 32-35℃ to remove bubbles to obtain spinning solution. (3) Add the spinning solution into the syringe, fix the syringe on the micro-injection pump, connect the needle of the injection pump to the positive terminal of the high voltage power supply, and connect the negative terminal to the receiving roller; control the electrospinning positive voltage to 15-18kV, the negative voltage to -1.5kV, the distance from the receiving roller to the needle to 5-15cm, and the spinning solution flow rate to 0.5-1.5mL / h to perform electrospinning and obtain Ag / TiO2 / GO doped PAN photocatalytic film; The preparation method of the chitosan-modified graphene oxide powder includes the following steps: (1) Disperse 1 part by mass of graphene oxide powder A in 10-15 parts by mass of deionized water, ultrasonically disperse for 1-3 hours, add 0.04-0.07 parts by mass of silane coupling agent KH550, reflux at 40-45℃ for 3-5 hours, centrifuge to obtain silane-modified graphene oxide powder. (2) Disperse the silane-modified graphene oxide powder prepared in step (1) in 10-15 parts by mass of methanol, ultrasonically disperse for 1-3 hours, add 0.06-0.08 parts by mass of glutaraldehyde in a water bath at 40-45℃, add 0.01-0.015 parts by mass of acetic acid dropwise, and reflux for 3-5 hours; add dilute nitric acid solution of chitosan, and continue to reflux for 3-6 hours at 40-45℃. After the reaction is completed, centrifuge to obtain chitosan-modified graphene oxide powder. The preparation method of the amino-modified graphene oxide powder includes the following steps: (1) Add graphene oxide powder B to deionized water and ultrasonically disperse at 0-5℃ for 30-40 min to obtain graphene oxide dispersion, wherein the concentration of graphene oxide is 0.1-0.2 g / L; (2) Add 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide to the graphene oxide dispersion, stir magnetically in an ice bath to obtain a mixed solution; continue to add ethylenediamine, react for 13-15 h, wash, dry to obtain amino-modified graphene oxide powder.

2. The method for preparing the Ag / TiO2 / GO-doped PAN photocatalytic film according to claim 1, characterized in that, The mass ratio of the graphene oxide powder A to chitosan is 1:(0.2-0.3).

3. The method for preparing the Ag / TiO2 / GO-doped PAN photocatalytic film according to claim 1, characterized in that, The size of graphene oxide powder A is 1-3 μm; number of layers: 1-3 layers.

4. The method for preparing the Ag / TiO2 / GO-doped PAN photocatalytic film according to claim 1, characterized in that, The size of graphene oxide powder B is 1-3 μm; number of layers: 1-3 layers.

5. The method for preparing the Ag / TiO2 / GO-doped PAN photocatalytic film according to claim 1, characterized in that, The ratio of the total mass of the mixed modified graphene oxide powder, tetrabutyl titanate, and silver nitrate to the mass of the water and ethanol mixture is 1:(7-10).

6. The method for preparing the Ag / TiO2 / GO-doped PAN photocatalytic film according to claim 1, characterized in that, The total mass ratio of Ag / TiO2 / GO composite material and PAN to N,N-dimethylformamide is 1:(8-12).

7. An Ag / TiO2 / GO-doped PAN photocatalytic film prepared by the preparation method according to any one of claims 1-6.

8. The application of the Ag / TiO2 / GO-doped PAN photocatalytic film prepared by the preparation method according to any one of claims 1-6, characterized in that, Applications of the Ag / TiO2 / GO doped PAN photocatalytic membrane in air purification, wastewater treatment, and antibacterial clothing.

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