Electromagnetic shielding composite material based on waste mask and PEDOT: PSS and preparation method and application thereof

Abstract

The invention relates to an electromagnetic shielding composite material based on waste masks and PEDOT: PSS and a preparation method and application thereof, and belongs to the technical field of materials for reflecting radiation and shielding electric fields and magnetic fields. The preparation method comprises the following steps: (1) introducing carboxyl on the surface of polypropylene fiber PP of the waste mask FM; (2) grafting polystyrolsulfon acid (PSS) to the surface of the waste mask FM with carboxyl; (3) coating poly (3, 4-ethylenedioxythiophene) PEDOT on the surface of the waste mask FM of which the surface is grafted with polystyrolsulfon acid (PSS); (4) loading Cu-MOF in situ; (5) adsorbing polytetrafluoroethylene (PTFE) nano plastic in the water body by utilizing FM / Cu-MOF / PEDOT: PSS; and (6) carrying out hot pressing on the FM / Cu-MOF / PEDOT: PSS on which the PTFE nano plastic is adsorbed. According to the invention, the two wastes, namely the waste mask and the nano plastic, are converted into the composite material with the electromagnetic shielding function, so that the effect of turning waste into wealth is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of materials for reflecting radiation and shielding electric and magnetic fields, and in particular to an electromagnetic shielding composite material based on discarded masks and PEDOT:PSS, and a preparation method and application thereof. Background Art

[0002] Microplastics generally refer to plastic particles with a particle size of less than 5mm. Microplastic pollution has a wide range and has been detected in soil and water. The small size of microplastic particles makes it possible for organisms to swallow them. They are ideal carriers of many hydrophobic organic pollutants and heavy metals, increasing the possibility of plastic additives or chemicals adsorbed on microplastics being released into the body after ingestion. Microplastic pollution has become one of the global environmental pollution problems. Although most of the plastic fragments produced in the waste plastic recycling process are used, a small amount of fragments still enter the sewage treatment plant with the workshop production wastewater. At present, sewage treatment plants mainly focus on COD in water. Cr While the removal of BOD5, TN, and TP is not done specifically, there is no treatment for microplastics in the water, allowing them to persist in the wastewater and enter rivers and oceans through sewage treatment plant discharge, thereby polluting water bodies in the natural environment. The PP fibers in the non-woven fabric of discarded masks have a mesh size of 0.5-30 microns. Therefore, the original discarded masks can only intercept and filter microplastics larger than 0.5 microns in water. They are unable to intercept and filter microplastics smaller than 0.5 microns, especially those at the nanoscale.

[0003] On the other hand, with the continuous advancement of human science and the rapid development of electronic information technology, a series of electromagnetic radiation, interference, and leakage caused by natural phenomena or man-made electronic devices have become one of the most pressing issues in today's society. Electronic pollution not only interferes with, degrades, or hinders the normal operation of peripheral equipment, but also poses a serious threat to human health. To address this problem, electromagnetic shielding materials that can effectively block the propagation of electromagnetic waves and reduce electromagnetic pollution have gradually attracted widespread attention. In recent years, conductive polymer composites (CPCs) have replaced metal materials as one of the most popular shielding materials due to their corrosion resistance, low cost, low density, and easy processing. The controllable conductivity of composites also provides significant room for the design of subsequent shielding materials. However, with the exception of a few polymers that are inherently conductive, most polymers are electrically insulating and have poor electromagnetic shielding performance. Therefore, how to improve the conductivity of CPCs to enhance electromagnetic shielding effectiveness is currently a hot topic in the field of electromagnetic shielding.

[0004] The existing Chinese patent application number 202111434746.X discloses a method for preparing an isolation functional network structure composite material after treating microplastics in wastewater. However, the conductive agent of this invention is adhered to the mask via polydopamine, which easily falls off when adsorbing microplastics in water. The existing Chinese patent application number 202311019301.4 discloses a method for preparing a hierarchical porous composite material using discarded masks and MOF. However, the MOF of this invention is directly loaded on the insulating mask fibers, which has limited improvement in conductivity and electromagnetic shielding performance.

[0005] Therefore, how to convert discarded masks and nanoplastics in water into electromagnetic shielding composite materials is the technical problem to be solved by this application. Summary of the Invention

[0006] In view of this, the present application provides an electromagnetic shielding composite material based on discarded masks and PEDOT:PSS, as well as its preparation method and application, which organically combines the treatment of nanoplastics in wastewater with the treatment of discarded masks, thereby reducing the pollution of discarded masks and effectively treating and removing nanoplastic pollutants in wastewater. The obtained composite material has certain application prospects in the field of electromagnetic shielding and can effectively overcome the defects of the above-mentioned prior art.

[0007] The first aspect of the present application provides a method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS, comprising the following steps:

[0008] (1) using the oxidizing effect of an oxidant to introduce carboxyl groups on the surface of the polypropylene fiber PP of the discarded mask FM to obtain a discarded mask FM with carboxyl groups on the surface;

[0009] (2) utilizing the high activity of the bridging agent to graft polystyrene sulfonic acid PSS onto the surface of the discarded mask FM with carboxyl groups, thereby obtaining the discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface;

[0010] (3) coating the surface of the discarded mask FM with polystyrene sulfonate PSS grafted on the surface of the discarded mask FM to form a highly conductive core-shell structure with polystyrene sulfonate PSS as the core and poly3,4-ethylenedioxythiophene PEDOT as the shell, i.e., the discarded mask FM with PEDOT:PSS grafted on the surface;

[0011] (4) In situ loading of Cu-MOF on the poly (3,4-ethylenedioxythiophene) PEDOT shell of discarded face mask FM grafted with PEDOT:PSS on the surface to obtain FM / Cu-MOF / PEDOT:PSS with adsorption effect;

[0012] (5) using FM / Cu-MOF / PEDOT:PSS to adsorb polytetrafluoroethylene (PTFE) nanoplastics in water to obtain FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastics;

[0013] (6) Hot pressing the FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastic to obtain a FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material.

[0014] Preferably, the oxidant is selected from one of a dilute nitric acid solution with a concentration of 0.1 to 5 mol / L, a potassium permanganate solution with a concentration of 0.01 to 1 mol / L, and an ammonium persulfate solution with a concentration of 0.01 to 1 mol / L; or

[0015] In step (1), the specific preparation process of the discarded mask FM with carboxyl groups on the surface is: after removing the nose bridge strip and ear straps of the discarded mask FM, cutting it into squares with a side length of 0.5 to 5 cm with scissors, soaking it in an oxidant solution for 5 to 200 minutes, taking it out and washing it with deionized water, and drying it to obtain the discarded mask FM with carboxyl groups on the surface.

[0016] Preferably, the bridging agent is selected from one of toluene diisocyanate TDI, diphenylmethane diisocyanate MDI, naphthalene 1,5-diisocyanate NDI, and p-phenylene diisocyanate; or

[0017] In step (2), the specific preparation process of the discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface is as follows: at room temperature, toluene diisocyanate TDI is placed in a reaction bottle, and then a catalyst with a molar ratio of 1: (5-20) to toluene diisocyanate TDI is added, and then polystyrene sulfonic acid PSS with a molar ratio equal to toluene diisocyanate TDI is added to a constant pressure funnel, and polystyrene sulfonic acid PSS is slowly added dropwise to toluene diisocyanate TDI for reaction. After the dropwise addition is completed, stirring is continued for 1-5 hours to complete the reaction, and then the discarded mask FM with carboxyl groups on the surface is added, and stirring is continued for 1-5 hours. The discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface is obtained after washing with toluene and deionized water in turn, and drying is performed; or

[0018] The catalyst is stannous octoate or dibutyltin dilaurate.

[0019] Preferably, in step (3), the specific preparation process of the highly conductive core-shell structure is:

[0020] The discarded mask FM with polystyrene sulfonate PSS grafted on the surface is dispersed in deionized water, and poly (3,4-ethylenedioxythiophene) PEDOT in an equal molar ratio to polystyrene sulfonate PSS is added, and the mixture is stirred for 1-5 hours. The mixture is centrifuged and dried to obtain the discarded mask FM with PEDOT:PSS grafted on the surface, wherein PEDOT:PSS forms a highly conductive core-shell structure on the surface of the discarded mask FM with polystyrene sulfonate PSS as the core and poly (3,4-ethylenedioxythiophene) PEDOT as the shell.

[0021] Preferably, in step (4), the specific preparation process of the FM / Cu-MOF / PEDOT:PSS is:

[0022] Dissolve copper nitrate trihydrate in water and disperse it evenly to obtain solution A; dissolve 2-methylimidazole in water and disperse it evenly to obtain solution B; place the discarded mask FM with PEDOT:PSS grafted on the surface into solution B, and then quickly add solution A to solution B, let it stand for 2-6 hours, then take it out and wash it with deionized water, and then dry it to obtain FM / Cu-MOF / PEDOT:PSS.

[0023] Preferably, in step (5), the specific preparation process of the FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastic is as follows:

[0024] The FM / Cu-MOF / PEDOT:PSS is fixed in a device containing wastewater containing polytetrafluoroethylene (PTFE) nanoplastics, and the nanoplastics in the wastewater are adsorbed. After the adsorption is saturated, the FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastics is obtained.

[0025] Preferably, the specific process of the adsorption treatment to reach adsorption saturation is:

[0026] After stirring the wastewater at room temperature for at least 60 minutes, the FM / Cu-MOF / PEDOT:PSS was taken out every 10-40 minutes, and adsorption saturation was considered to be reached when the amount of nanoplastics in a fixed field of view no longer increased under an electron microscope.

[0027] Preferably, in step (6), the hot pressing temperature is 160-190° C., and the hot pressing time is 15-40 min.

[0028] The second aspect of the present application further provides an electromagnetic shielding composite material, which is prepared by the above-mentioned method.

[0029] A third aspect of the present application also provides applications of the above-mentioned electromagnetic shielding composite material in the field of electromagnetic shielding.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] (1) In this application, insulating PSS is first grafted onto the fiber surface of FM, and then the conductive polymer PEDOT is deposited on the PSS surface, and Cu-MOF is further grown in situ on the high-conductivity PEDOT layer, so that Cu-MOF is connected through conductive channels, ultimately improving the material's conductivity and electromagnetic shielding performance.

[0032] (2) This application increases the dielectric properties of FM / Cu-MOF / PEDOT:PSS by adsorbing PTFE nanoplastics, ultimately improving the electromagnetic shielding performance of the material.

[0033] (3) Part of the raw materials of the hierarchical porous composite material of the present application are derived from discarded masks, which improves the waste recycling efficiency, promotes the recycling of resources, and transforms discarded masks and nanoplastics into composite materials with electromagnetic shielding function, thus turning waste into treasure; the cost of raw materials is relatively low, thereby reducing the total cost of preparing the composite material of the present application and facilitating mass production; in addition, the process of the present application is simple, and there is no need for additional disinfection and sterilization of discarded masks. The melt blending process is carried out at high temperature, and the high-temperature melting stage can simultaneously complete the uniform mixing of the raw materials and the disinfection and sterilization of the raw materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following briefly introduces the drawings required for use in the description of the present application or the prior art. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0035] Figure 1 : Infrared analysis (A), XRD analysis (B) and thermogravimetric analysis (C) of Comparative Example 2 and Comparative Example 1, nitrogen adsorption-desorption isotherm and pore size distribution (D), XPS spectrum (E) of Comparative Example 1, wherein E1: XPS rough scan of the sample of Comparative Example 1, E2: C of the sample of Comparative Example 1 1s Fine scan, E3: N of the sample of comparative example 1 1s Fine scan, E4: S of the sample of Comparative Example 1 2p Fine scanning image, SEM image of comparative example 2 (F1), SEM image of comparative example 1 (F2) and element distribution map of comparative example 1 (F3);

[0036] Figure 2: SEM image (A) and element distribution (B) of Example 1 after adsorption of PTFE nanoplastics, the influence of time (C), pH value (D), and PTFE size (E) on the adsorption amount of Comparative Example 3 and Example 1;

[0037] Figure 3 : The conductive properties (A) and electromagnetic shielding properties (B, C) of Example 1 and Comparative Examples 1-3. DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of this application more clear, the technical solutions of this application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of this application, not all of them. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0039] Unless otherwise specified, the experimental methods used in the examples of this application are all conventional methods.

[0040] In the following examples and comparative examples, unless otherwise specified, all raw materials can be purchased commercially or prepared by conventional methods.

[0041] Example 1

[0042] A method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS comprises the following steps:

[0043] (1) Carboxyl groups were introduced onto the surface of polypropylene (PP) fibers of discarded face masks (FM) using the oxidative action of dilute nitric acid. The concentration of the dilute nitric acid was 0.5 mol / L. The specific process was as follows: after removing the nose bridge and ear straps from the discarded face masks, the masks were cut into 1 cm squares with scissors and immersed in dilute nitric acid for 20 min. After removal, the masks were rinsed with deionized water and dried for later use.

[0044] (2) Using the high activity of TDI, polystyrene sulfonic acid (PSS) is grafted onto the surface of FM. The specific process is as follows: at room temperature, 10 g of TDI is placed in a reaction bottle, 4.66 g of stannous octoate is added, and then PSS in an equal molar ratio to TDI is added into a constant pressure funnel. Polystyrene sulfonic acid PSS is slowly added dropwise to toluene diisocyanate TDI for reaction. After the addition is complete, stirring is continued for 1 hour to allow the reaction to complete. Then, the FM with a carboxyl group on the surface obtained in step (1) is added, stirring is continued for 1 hour, and the FM with PSS grafted on the surface is obtained by washing and drying with toluene and deionized water in turn.

[0045] (3) Poly(3,4-ethylenedioxythiophene) (PEDOT) is coated on the surface of a discarded mask FM grafted with polystyrene sulfonic acid (PSS), forming a highly conductive core-shell structure on the surface of the discarded mask FM, with PSS as the core and PEDOT as the shell. The specific process is as follows: the FM grafted with PSS on the surface obtained in step (2) is dispersed in deionized water, PEDOT is added in an equal molar ratio to PSS, stirred for 1 hour, centrifuged, and dried to obtain a FM grafted with PEDOT:PSS on the surface, wherein PEDOT:PSS forms a highly conductive core-shell structure on the surface of the FM, with PSS as the core and PEDOT as the shell.

[0046] (4) In situ loading of Cu-MOF on the PEDOT shell of the discarded mask FM with PEDOT:PSS grafted on the surface to obtain FM / Cu-MOF / PEDOT:PSS with adsorption effect. The specific process is as follows: 0.2 g of copper nitrate trihydrate is dissolved in 40 ml of water and dispersed evenly to obtain solution A; 1.5 g of 2-methylimidazole is dissolved in 40 ml of water and dispersed evenly to obtain solution B. The FM with PEDOT:PSS grafted on the surface obtained in step (3) is fixed in solution B, and then solution A is quickly added to solution B. After standing for 4 hours, the FM is taken out, washed with deionized water, and dried to obtain FM / Cu-MOF / PEDOT:PSS.

[0047] (5) Using FM / Cu-MOF / PEDOT:PSS to adsorb polytetrafluoroethylene (PTFE) nanoplastics in water. The specific process is as follows: the FM / Cu-MOF / PEDOT:PSS is fixed in a device containing wastewater containing PTFE nanoplastics, and the nanoplastics in the wastewater are adsorbed. After reaching adsorption saturation, the discarded masks containing nanoplastics are taken out to obtain the discarded masks; the adsorption process to reach adsorption saturation is as follows: after stirring the wastewater at room temperature for at least 60 minutes, the discarded masks are taken out every 10 minutes and observed under an electron microscope. If the amount of nanoplastics in the fixed field of view no longer increases, it is considered that adsorption saturation has been reached.

[0048] (6) Hot pressing the FM / Cu-MOF / PEDOT:PSS adsorbed with PTFE nanoplastics to obtain a FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material. The specific process is as follows: hot pressing the FM / Cu-MOF / PEDOT:PSS adsorbed with PTFE nanoplastics at a temperature of 180°C and a time of 30 minutes. Finally, a FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material is obtained.

[0049] Example 2

[0050] The FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material provided in this embodiment can refer to Example 1, except that the dilute nitric acid in step (1) is replaced with 0.05 mol / L ammonium persulfate.

[0051] Example 3

[0052] The FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material provided in this embodiment can refer to Example 1, except that the TDI in step (2) is replaced by an equimolar amount of diphenylmethane diisocyanate (MDI).

[0053] Comparative Example 1

[0054] Comparative Example 1 is FM / Cu-MOF / PEDOT:PSS without adsorption of PTFE nanoplastics, named FM / Cu-MOF / PEDOT:PSS (before adsorption).

[0055] Comparative Example 2

[0056] Comparative Example 2 is an original discarded mask without adsorption of PTFE nanoplastics, named original FM (before adsorption).

[0057] Comparative Example 3

[0058] Comparative Example 3 is an original discarded mask subjected to the same PTFE nanoplastic adsorption treatment as in Example 1, and is named original FM (after adsorption).

[0059] Test Case

[0060] The removal rate of PTFE nanoplastics in wastewater was measured for Example 1 and Comparative Example 1 respectively. Cr , BOD5, TN and TP were effectively removed. When calculating the removal rate of PTFE nanoplastics, the total starting concentration of PTFE nanoplastics in the wastewater was 0.1-0.5 mg / ml, and the particle size range was 10-200 nm.

[0061] When carrying out conductivity and electromagnetic shielding performance tests, Example 1 is FM / Cu-MOF / PEDOT:PSS adsorbed with PTFE nanoplastics, named FM / Cu-MOF / PEDOT:PSS (after adsorption). Comparative Example 1 is FM / Cu-MOF / PEDOT:PSS without adsorbing PTFE nanoplastics, named FM / Cu-MOF / PEDOT:PSS (before adsorption). Comparative Example 2 is the original discarded mask without adsorbing PTFE nanoplastics, named original FM (before adsorption). Comparative Example 3 is the original discarded mask that performs the same PTFE nanoplastic adsorption process as Example 1, named original FM (after adsorption). Example 1, compared with Comparative Example 3, illustrates that introducing Cu-MOF and PEDOT:PSS can effectively increase the electromagnetic shielding effectiveness of the mask.

[0062] Comparison between Example 1 and Comparative Example 1 shows that adsorption of PTFE nanoplastics can also effectively increase the electromagnetic shielding effectiveness of the mask.

[0063] Figure 1 The composition and structure of Comparative Example 1 were confirmed by infrared, XRD, thermogravimetric, and XPS. SEM showed that the fiber surface of Comparative Example 2 was originally smooth, but became rough after the introduction of PEDOT:PSS and Cu-MOF. EDS confirmed that PEDOT:PSS and Cu-MOF were evenly distributed on the FM surface. BET analysis showed that the specific surface area of ​​Comparative Example 1 was 213 m 2 ·g -1 The average pore size is 2.19 nm, which provides a basis for the adsorption of PTFE nanoplastics.

[0064] Figure 2 (A) confirmed that PTFE nanoplastic particles were uniformly adsorbed on the surface of Example 1, Figure 2 The evenly distributed F element in (B) confirms that the PTFE nanoplastic is evenly distributed on the surface of Example 1. Figure 2 (C) shows that Example 1 reaches adsorption equilibrium within 20 minutes, and the final adsorption amount in 120 minutes slowly increases to 78.2 mg / g, while Comparative Example 3 reaches an adsorption equilibrium amount of 6.7 mg / g within 20 minutes and then stops increasing. Figure 2 (D) shows that the adsorption capacity of Example 1 can remain stable in a water environment with a Ph value of 5-9. Figure 2 (E) shows that the adsorption capacity of Example 1 can be maintained when the size of the PTFE nanoplastic is 100-1000 nm.

[0065] Figure 3 (A) shows that the conductivity of Example 1 increases after adsorption of PTFE. Figure 3(B, C) show that the electromagnetic shielding effectiveness of Example 1 is increased after the adsorption of PTFE. This may be because the adsorption of PTFE forms an isolated conductive network in the material, which improves the dissipation path of electromagnetic waves inside the material.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS, characterized in that: The following steps are involved: (1) using the oxidizing effect of an oxidant to introduce carboxyl groups on the surface of the polypropylene fiber PP of the discarded mask FM, thereby obtaining a discarded mask FM with carboxyl groups on the surface; (2) utilizing the high activity of the bridging agent to graft polystyrene sulfonic acid PSS onto the surface of the discarded mask FM with carboxyl groups, thereby obtaining the discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface; (3) coating the surface of the discarded mask FM with polystyrene sulfonate PSS grafted on the surface of the discarded mask FM to form a highly conductive core-shell structure with polystyrene sulfonate PSS as the core and poly3,4-ethylenedioxythiophene PEDOT as the shell, i.e., the discarded mask FM with PEDOT:PSS grafted on the surface; (4) In situ loading of Cu-MOF on the poly (3,4-ethylenedioxythiophene) PEDOT shell of discarded face mask FM grafted with PEDOT:PSS on the surface to obtain FM / Cu-MOF / PEDOT:PSS with adsorption effect; (5) using FM / Cu-MOF / PEDOT:PSS to adsorb polytetrafluoroethylene (PTFE) nanoplastics in water to obtain FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastics; (6) The FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastics is hot-pressed to obtain a FM / Cu-MOF / PEDOT:PSS electromagnetic shielding composite material.

2. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 1, characterized in that: The oxidant is selected from one of a dilute nitric acid solution with a concentration of 0.1 to 5 mol / L, a potassium permanganate solution with a concentration of 0.01 to 1 mol / L, and an ammonium persulfate solution with a concentration of 0.01 to 1 mol / L; or In step (1), the specific preparation process of the discarded mask FM with carboxyl groups on the surface is: after removing the nose bridge strip and ear straps of the discarded mask FM, cutting it into squares with a side length of 0.5 to 5 cm with scissors, soaking it in an oxidant solution for 5 to 200 minutes, taking it out and washing it with deionized water, and drying it to obtain the discarded mask FM with carboxyl groups on the surface.

3. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 1, characterized in that: The bridging agent is selected from one of toluene diisocyanate TDI, diphenylmethane diisocyanate MDI, naphthalene 1,5-diisocyanate NDI, and p-phenylene diisocyanate; or In step (2), the specific preparation process of the discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface is as follows: at room temperature, toluene diisocyanate TDI is placed in a reaction bottle, and then a catalyst with a molar ratio of 1: (5-20) to toluene diisocyanate TDI is added, and then polystyrene sulfonic acid PSS with a molar ratio equal to toluene diisocyanate TDI is added to a constant pressure funnel, and polystyrene sulfonic acid PSS is slowly added dropwise to toluene diisocyanate TDI for reaction. After the dropwise addition is completed, stirring is continued for 1-5 hours to complete the reaction, and then the discarded mask FM with carboxyl groups on the surface is added, and stirring is continued for 1-5 hours. The discarded mask FM with polystyrene sulfonic acid PSS grafted on the surface is obtained after washing with toluene and deionized water in turn, and drying is performed; or The catalyst is stannous octoate or dibutyltin dilaurate.

4. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 1, characterized in that: In step (3), the specific preparation process of the highly conductive core-shell structure is as follows: The discarded mask FM with polystyrene sulfonate PSS grafted on the surface is dispersed in deionized water, and poly (3,4-ethylenedioxythiophene) PEDOT in an equal molar ratio to polystyrene sulfonate PSS is added, and the mixture is stirred for 1-5 hours. The mixture is centrifuged and dried to obtain the discarded mask FM with PEDOT:PSS grafted on the surface, wherein PEDOT:PSS forms a highly conductive core-shell structure on the surface of the discarded mask FM with polystyrene sulfonate PSS as the core and poly (3,4-ethylenedioxythiophene) PEDOT as the shell.

5. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 4, characterized in that: In step (4), the specific preparation process of the FM / Cu-MOF / PEDOT:PSS is as follows: Dissolve copper nitrate trihydrate in water and disperse it evenly to obtain solution A; dissolve 2-methylimidazole in water and disperse it evenly to obtain solution B; place the discarded mask FM with PEDOT:PSS grafted on the surface into solution B, and then quickly add solution A to solution B, let it stand for 2-6 hours, then take it out and wash it with deionized water, and then dry it to obtain FM / Cu-MOF / PEDOT:PSS.

6. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 1, characterized in that: In step (5), the specific preparation process of the FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastic is as follows: The FM / Cu-MOF / PEDOT:PSS is fixed in a device containing wastewater containing polytetrafluoroethylene (PTFE) nanoplastics, and the nanoplastics in the wastewater are adsorbed. After the adsorption is saturated, the FM / Cu-MOF / PEDOT:PSS adsorbed with polytetrafluoroethylene (PTFE) nanoplastics is obtained.

7. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 6, characterized in that: The specific process of the adsorption treatment to achieve adsorption saturation is: After stirring the wastewater at room temperature for at least 60 minutes, the FM / Cu-MOF / PEDOT:PSS was taken out every 10-40 minutes, and adsorption saturation was considered to be reached when the amount of nanoplastics in a fixed field of view no longer increased under an electron microscope.

8. The method for preparing an electromagnetic shielding composite material using discarded masks and PEDOT:PSS according to claim 1, characterized in that: In step (6), the hot pressing temperature is 160-190° C., and the hot pressing time is 15-40 min.

9. An electromagnetic shielding composite material, characterized in that: An electromagnetic shielding composite material prepared by the method according to any one of claims 1 to 8.

10. Use of the electromagnetic shielding composite material according to claim 9 in the field of electromagnetic shielding.

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