A method and application for degrading waste plastics using plasma and application of plastic degradation products

Abstract

The application belongs to the technical field of waste plastic treatment, and particularly relates to a method for degrading waste plastics by using plasma and application and application of plastic degradation products, and comprises the following steps: 1) pretreating waste plastics to obtain micro plastics; 2) mixing the obtained micro plastics with a combustion improver to wet the micro plastics, and then reacting the micro plastics in a plasma environment to degrade the micro plastics. Compared with the prior art, the application solves the problems of the prior art, such as complicated operation, high cost, complex product distribution, generation of toxic gases in a high-temperature environment and the like, and realizes rapid degradation of waste plastics at normal temperature and pressure and without a catalyst.

Description

Technical Field

[0001] This invention belongs to the field of waste plastic treatment technology, specifically relating to a method and application of plasma degradation of waste plastics, as well as the application of plastic degradation products. Background Technology

[0002] The rapid development and mass production of plastic products have brought great convenience to human life, but have also caused serious harm to the human environment. Due to the difficulty in degrading waste plastics, soil and water sources are polluted, posing a serious threat to animals and plants. Furthermore, microplastics enter the human body through the food chain, posing potential health hazards. Therefore, how to effectively treat and utilize waste plastics to reduce their environmental impact has become a critical issue that urgently needs to be addressed.

[0003] Traditional waste plastic treatment methods, such as landfill and incineration, while reducing waste volume, also generate secondary pollution and waste energy, failing to fundamentally solve the plastic pollution problem. Considering that waste plastics originate from fossil fuels, converting them into energy is a promising approach, not only reducing plastic emissions but also effectively protecting existing fossil resources. Pyrolysis is the primary method for plastic degradation. Although significant progress has been made in recent decades in pyrolysis gasification reaction parameters, catalysts, and process design, the high endothermic performance of the degradation process requires higher energy input, which is a major obstacle to its economic viability. Furthermore, low degradation efficiency, long processing time, significant environmental impact, and the complexity of product distribution are other factors limiting the application of this method. In response to this situation, developing new, environmentally friendly, and efficient waste plastic treatment technologies has become an important task.

[0004] Low-temperature plasma, due to its low macroscopic temperature and high particle energy, has become a research hotspot in the field of waste plastic treatment. Xiao et al. (Xiao, H.; Harding, J.; Lei, S. et al, Hydrogen and aromatics recovery through plasma-catalytic pyrolysis of waste polypropylene. J. Clean. Prod. 2022, 350, 131467.) used a coaxial plasma reactor to perform two-stage fixed-bed pyrolysis of polypropylene on ZSM-5 catalyst, achieving an H2 production rate of 4.19 mmol / g. This improved the selectivity for benzene, toluene, and xylene while inhibiting wax formation. Ma et al. (Ma, Y.; Gao, N.; Quan, C. et al., High-yield H2 production from HDPE through integrated pyrolysis and plasma-catalysis reforming process. Chem. Eng. J. 2024, 479, 147877.) explored the effects of an integrated pyrolysis and plasma-catalytic reforming system on the degradation of polyethylene (PE). At 500℃, the synergistic effect reached 250.98%, and the total gas yield and H2 yield of PE under plasma-catalytic reforming were 146.5 mmol / g and 102.52 mmol / g, respectively. While the above technology achieves the required plastic degradation capacity, it suffers from several drawbacks, including complex operation, high cost, complex product distribution, generation of toxic gases at high temperatures, cumbersome catalyst synthesis and regeneration processes, and catalyst particle aggregation and carbon deposition leading to deactivation during high-temperature reactions. These factors are key limitations to its widespread application.

[0005] Therefore, there is a need to provide a waste plastic treatment method that is simple to process, produces usable products, and generates few pollutants. Summary of the Invention

[0006] The purpose of this invention is to provide a method and application for degrading waste plastics using plasma, as well as the application of plastic degradation products, in order to solve at least one of the above-mentioned problems. This solves the problems of complicated operation, high cost, complex product distribution, and toxic gas generation in high-temperature environments in the prior art. This solution achieves rapid degradation of waste plastics under normal temperature and pressure conditions without catalysts.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] The first aspect of this invention discloses a method for degrading waste plastics using plasma, comprising the following steps:

[0009] 1) Pre-treat waste plastics to obtain microplastics;

[0010] 2) The obtained microplastics are mixed with a combustion accelerant to wet the microplastics, and then a reaction is carried out in a plasma environment to degrade the microplastics.

[0011] Preferably, the pretreatment includes preliminary crushing, fine crushing and particle size classification, wherein the particle size of the microplastics is 110-130 μm.

[0012] More preferably, the pretreatment is as follows: first, the waste plastic is sorted, washed and dried, then the waste plastic is added to a shear crusher for preliminary crushing to obtain plastic particles with a particle size of 10-30mm, then the plastic particles are immersed in a low-temperature resistant container filled with liquid nitrogen to make the plastic brittle, then the brittle plastic particles are finely crushed by an ultrasonic crusher, and finally the particle size is classified by an air classifier to obtain microplastics with a particle size of 110-130μm.

[0013] Further preferred methods include: washing with deionized water 3-5 times; using 95% ethanol and washing with ethanol 3-5 times; drying with a vacuum freeze dryer at a temperature of -50 to -70°C, a pressure of 1-10 Pa, and a drying time of 20-24 hours; using a shear crusher with a power of 0.2-0.4 kW and a crushing time of 30-50 minutes; using liquid nitrogen for cooling at a temperature of -100°C to -196°C and a cooling time of 10-30 minutes; using a stainless steel cryogenic storage tank as the cryogenic container; using an ultrasonic pulverizer with a power of 0.5-2 kW and a frequency of 20-40 kHz; and using an airflow sieve with a power of 0.75-7.5 kW and a stainless steel screen with a mesh size of 120-150 mesh.

[0014] Preferably, the ratio of microplastics to combustion improver is 100-200 mg: 30-70 μL.

[0015] Preferably, the waste plastics include one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyurethane, polyamide, and epoxy resin.

[0016] Preferably, when the pH of the combustion accelerator is acidic, the combustion accelerator is peracetic acid and / or acetic acid (the volume ratio of peracetic acid to acetic acid is (0-2):(0-2)); when the pH of the combustion accelerator is neutral, the combustion accelerator is water; when the pH of the combustion accelerator is alkaline, the combustion accelerator is ammonia.

[0017] Preferably, in the plasma environment, the plasma is a dielectric barrier discharge plasma with a discharge power of 80-300W and a discharge frequency of 50-60Hz.

[0018] Preferably, the reaction is carried out at room temperature and pressure for 5-180 minutes.

[0019] Preferably, the reaction is carried out under a certain gas flow, wherein the certain gas flow is argon and / or oxygen, and the total gas velocity is 10-70 min / mL.

[0020] The second aspect of this invention discloses the application of a method for degrading waste plastics using plasma as described above in the field of solid waste treatment.

[0021] The third aspect of this invention discloses the application of waste plastic degradation products in the field of catalysis. The waste plastic degradation products are obtained by plasma degradation of waste plastics as described above. The waste plastic degradation products are one or more of solid crystalline carbon and gaseous H2, CO, CH4 and CO2.

[0022] This invention relates to a highly efficient plasma degradation method for plastics, conducted under ambient temperature and pressure conditions, reducing energy consumption and costs. First, ultrasonic-assisted cryogenic pulverization technology is used to process waste plastics into uniform microplastics, significantly increasing surface area and enhancing contact efficiency with plasma. Next, a mixture of oxygen and argon is introduced, optimizing plasma stability and oxidation reactions to improve the degradation rate. The use of a combustion aid further enhances the degradation rate, promoting the conversion of microplastics into crystalline carbon and gas. The crystalline carbon can be used to prepare highly efficient composite catalysts, and the gaseous products can be applied in thermocatalysis fields such as CO2 hydrogenation, CO hydrogenation, and CH4 dry reforming. This method is not only highly efficient and environmentally friendly but also simplifies subsequent processing and improves resource utilization. Compared with existing technologies, this invention primarily addresses the rapid degradation of waste plastics to obtain crystalline carbon and gaseous products under ambient temperature and pressure conditions without a catalyst. This invention has significant energy-saving and environmentally friendly advantages in improving degradation rate, processing efficiency, and resource utilization, solving many key problems in traditional methods.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention uses waste plastics as raw materials and utilizes ultrasonic-assisted low-temperature pulverization technology and DBD plasma discharge to degrade microplastics into crystalline carbon and gaseous products. The microplastics possess uniform particle shape and a large specific surface area, thereby improving their contact efficiency with plasma. This process is simple, efficient, environmentally friendly, and operates under mild reaction conditions (room temperature and pressure). It requires no catalyst, and the product distribution is simple. A specific oxygen and argon gas mixture optimizes plasma stability and oxidation reaction efficiency. The use of a combustion aid further enhances degradation efficiency, promoting the conversion of microplastics into crystalline carbon and gas. The crystalline carbon can be used to prepare composite catalysts for photocatalysis, electrocatalysis, and thermocatalysis. The gas can be applied in related thermocatalytic fields (such as CO2 hydrogenation, CO hydrogenation, and CH4 dry reforming). This enables the recycling of waste plastics and has promising application prospects.

[0025] More specifically:

[0026] 1) The plasma degradation method of the present invention is simple, efficient and environmentally friendly. Compared with traditional plastic degradation, it has the advantages of low energy consumption and equipment cost, simple product distribution, milder reaction conditions (room temperature and pressure), applicability to mixed plastics and no need for catalyst, and faster and more efficient reaction process.

[0027] 2) This invention utilizes ultrasonic-assisted low-temperature pulverization technology to pulverize waste plastics into microplastics. Ultrasonic technology can significantly improve pulverization efficiency, reduce thermal damage, and obtain uniform microplastic particles. The application of this technology can increase the specific surface area of ​​plastics, allowing for more thorough contact between plasma and plastics, which makes subsequent plasma treatment more efficient.

[0028] 3) In the plasma degradation of microplastics process of this invention, a gas mixture (oxygen and argon) is introduced. The combination of the gas mixture optimizes the stability of the plasma and the oxidation reaction. Oxygen provides the required oxidation environment, while argon provides a stable environment, avoiding excessive oxidation and side reactions, and ensuring the stability and high efficiency of the treatment process.

[0029] 4) In the plasma degradation of microplastics of this invention, a combustion aid (a mixture of acetic acid and peracetic acid, water or ammonia) is added. By optimizing different ratios and adjusting the pH, an optimal degradation environment is formed. The combustion aid not only accelerates the degradation process, but also provides the optimal reaction environment through pH regulation, which increases the degradation rate by lowering the reaction energy barrier.

[0030] 5) This invention utilizes plasma degradation of microplastics to obtain crystalline carbon and gaseous products, demonstrating the high efficiency and selectivity of the degradation process. The crystalline carbon can be used to prepare composite catalysts for photocatalysis, electrocatalysis, and thermocatalysis, while the gaseous products can be applied to related thermocatalysis fields (such as CO2 hydrogenation, CO hydrogenation, and CH4 dry reforming). Attached Figure Description

[0031] Figure 1 The image shows an SEM image of the product after plasma degradation of waste plastic in Example 1, where a is undegraded PE and b is degraded PE.

[0032] Figure 2 The image shows the XRD pattern of the product after plasma degradation of waste plastics in Example 1.

[0033] Figure 3 The graph shows the effect of different proportions of combustion improvers on the removal rate of waste plastics by plasma degradation in Examples 1-5.

[0034] Figure 4 The graph shows the effect of different proportions of mixed gas on the removal rate of waste plastics by plasma degradation in Examples 1 and 6-10.

[0035] Figure 5 The graph shows the effect of different pH values ​​of combustion aids on the removal rate of waste plastics by plasma degradation in Examples 1 and 11-15.

[0036] Figure 6 This is a graph showing the gas selectivity of different pH combustion aids for plasma degradation of waste plastics in Examples 1 and 11-15.

[0037] Figure 7 Raman spectroscopy plots of the products from plasma degradation of waste plastics in Examples 1 and 11-15 using combustion aids with different pH values.

[0038] Figure 8 The images show the FTIR spectra of the products from plasma degradation of waste plastics in Examples 1 and 11-15 when different pH combustion aids were used.

[0039] Figure 9 The water contact angle diagrams are shown for the products of plasma degradation of waste plastics in Examples 1 and 11-15 when different pH combustion aids were used.

[0040] Figure 10 The above are gas chromatograms of the products from plasma degradation of waste plastics when different pH combustion aids were used in Examples 1 and 11-15. Detailed Implementation

[0041] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] Unless otherwise specified, the reagents used in the following description are commercially available products and the methods used are those known in the art.

[0043] A method for degrading waste plastics using plasma, the method comprising the following steps:

[0044] 1) Pre-treat waste plastics to turn them into microplastics. The specific process is as follows: First, sort, wash and dry the waste plastics. Then, add the waste plastics to a shear crusher for preliminary crushing to obtain plastic particles with a particle size of 10-30mm. Next, immerse the plastic particles in a low-temperature resistant container filled with liquid nitrogen to make the plastic brittle. Then, use an ultrasonic crusher to refine and crush the brittle plastic particles. Finally, use an air classifier to classify the particle size to obtain microplastics with a particle size of 110-130μm.

[0045] 2) Place the microplastics in a plasma reactor, add a combustion aid to make the microplastics wet, and then use plasma to react the mixture to obtain crystalline carbon and high-value-added gaseous products.

[0046] Further, in step 1), the washing is performed 3-5 times with deionized water, the ethanol concentration is 95%, and the washing is performed 3-5 times with ethanol; the drying is carried out using a vacuum freeze dryer at a drying temperature of -50 to -70°C, a drying pressure of 1-10 Pa, and a drying time of 20-24 hours.

[0047] Furthermore, in step 1), the power of the shear crusher is 0.2-0.4kW, the crushing time is 30-50min; the liquid nitrogen cooling temperature is -100℃~-196℃, the cooling time is 10-30min, and the low-temperature container is a stainless steel cryogenic storage tank.

[0048] Further, in step 1), the ultrasonic pulverizer has a power of 0.5-2kW, a frequency of 20-40kHz, and a pulverization time of 20-40min; the air classifier has a power of 0.75-7.5kW, and the stainless steel screen has a mesh size of 120-150 mesh.

[0049] Further, in step 2), the waste plastics include one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyurethane, polyamide, and epoxy resin.

[0050] Furthermore, in step 2), the plasma is dielectric barrier discharge (DBD) plasma with a discharge power of 80-300W and a discharge frequency of 50-60Hz.

[0051] Furthermore, in step 2), the plasma treatment temperature is room temperature, the treatment pressure is atmospheric pressure, and the treatment time is 5-180 min.

[0052] Further, in step 2), the plasma reaction process is carried out under ventilated conditions, with the volume percentage of argon to oxygen being (0-100 vol%):(0-100 vol%), and the total gas velocity of the mixture being 10-70 min / mL.

[0053] Further, in step 2), the plasma reaction process is carried out with the addition of a combustion accelerant. When the pH of the combustion accelerant is acidic (3.5-6), the volume ratio of peracetic acid to acetic acid is (0-2):(0-2); when the pH of the combustion accelerant is neutral (7), the combustion accelerant is water; when the pH of the combustion accelerant is alkaline (9), the combustion accelerant is ammonia.

[0054] Furthermore, the volume ratio of microplastics to combustion improver is 100-200 mg: 30-70 μL.

[0055] Furthermore, in step 2), the products of plasma degradation of microplastics are only solids and gases. The solid is crystalline carbon, and the gas is one or more of H2, CO, CH4, and CO2.

[0056] This invention uses waste plastics as raw materials and utilizes ultrasonic-assisted low-temperature pulverization technology and DBD plasma discharge to degrade microplastics into crystalline carbon and gaseous products. The microplastics possess uniform particle shape and a large specific surface area, thereby improving their contact efficiency with plasma. This process is simple, efficient, environmentally friendly, and operates under mild reaction conditions (room temperature and pressure). It requires no catalyst, and the product distribution is simple. A specific oxygen and argon gas mixture optimizes plasma stability and oxidation reaction efficiency. The use of a combustion aid further enhances degradation efficiency, promoting the conversion of microplastics into crystalline carbon and gas. The crystalline carbon can be used to prepare composite catalysts for photocatalysis, electrocatalysis, and thermocatalysis. The gas can be applied in related thermocatalytic fields (such as CO2 hydrogenation, CO hydrogenation, and CH4 dry reforming). This enables the recycling of waste plastics and has promising application prospects.

[0057] Example 1:

[0058] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0059] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0060] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 2HAc / 1PAA.

[0061] Figure 1 This is a SEM image of the product after plasma degradation of PE in this embodiment. Figure 1 It can be seen that after plasma treatment, the solid becomes an irregular object with many cracks and elongated shapes. This indicates that plasma treatment may alter the surface structure and chemical properties of PE-4, leading to the breakage and carbonization of PE-4 molecules.

[0062] Figure 2 This is the XRD pattern of the product after plasma degradation of PE in this embodiment. Figure 2 It can be seen that the diffraction peaks of PE-4 disappear at approximately 21.6° and 24° (PDF#4-1995), indicating that the plasma discharge reaction process may lead to the breakage, cross-linking, compounding, or other forms of structural changes in the polyethylene molecular chains.

[0063] Example 2:

[0064] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0065] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0066] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 0:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 0HAc / 1PAA.

[0067] Example 3:

[0068] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0069] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0070] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 1:2) with pH 4 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 1HAc / 2PAA.

[0071] Example 4:

[0072] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0073] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0074] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid and peracetic acid volume ratio 1:1) with pH 4 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 1HAc / 1PAA.

[0075] Example 5:

[0076] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0077] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0078] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid and peracetic acid volume ratio 1:0) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 1HAc / OPAA.

[0079] Figure 3 This is a graph showing the effect of different proportions of combustion improvers on the removal rate of PE degraded by plasma in Examples 1-5. Figure 3 It can be seen that acetic acid alone has a relatively slow degradation process due to insufficient oxidizing power. Peracetic acid alone, although it has strong oxidizing power, lacks a suitable acidic environment, which leads to instability in the plasma reaction and reduces the overall degradation efficiency. When the ratio of HAc:PAA to combustion promoters is 2:1, the removal capacity of PE-4 is the greatest because they can produce the best synergistic effect. The acidic environment provided by acetic acid enhances the ionization in the plasma and promotes the generation of free radicals. These free radicals can effectively react with the oxidant generated by peracetic acid and accelerate the decomposition of PE.

[0080] Example 6:

[0081] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0082] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0083] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (0 vol% O2 and 100 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 0O2 / 100Ar.

[0084] Example 7:

[0085] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0086] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0087] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (10 vol% O2 and 90 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 10O2 / 90Ar.

[0088] Example 8:

[0089] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0090] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0091] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (20 vol% O2 and 80 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 20O2 / 80Ar.

[0092] Example 9:

[0093] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0094] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0095] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with pH 4 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (40 vol% O2 and 60 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 40O2 / 60Ar.

[0096] Example 10:

[0097] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0098] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0099] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (50 vol% O2 and 50 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as 50O2 / 50Ar.

[0100] Figure 4 This is a graph showing the effect of different proportions of mixed gas on the removal rate of PE by plasma degradation in Examples 1 and 6-10; Figure 4 It can be seen that in a single argon atmosphere, although the plasma has good stability, it lacks sufficient oxidizing power, resulting in a low degradation rate. When the oxygen ratio is high, although the oxidizing power increases, the stability of the plasma decreases, causing the degradation rate to basically not increase, and even instability may occur. The degradation rate reaches its optimal level when the gas ratio of oxygen to argon is 30 vol% O2: 70 vol% Ar. At this ratio, the oxygen concentration is sufficient to generate enough active oxygen species to effectively degrade PE, while the high proportion of argon ensures the stability and uniformity of the plasma, thus achieving efficient degradation.

[0101] Example 11:

[0102] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0103] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0104] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 3.5 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as PE-3.5.

[0105] Example 12:

[0106] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0107] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0108] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with pH 5 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as PE-5.

[0109] Example 13:

[0110] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0111] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0112] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 6 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled as PE-6.

[0113] Example 14:

[0114] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0115] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0116] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of water-based combustion aid with pH 7, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene produced under these conditions is labeled as PE-7.

[0117] Example 15:

[0118] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0119] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0120] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of ammonia water (pH 9) as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene produced under these conditions is labeled PE-9.

[0121] Figure 5 The graph shows the effect of different pH values ​​of combustion aids on the removal rate of waste plastics by plasma degradation in Examples 1 and 11-15. Figure 5 The results show that while lower pH can promote the generation of reactive oxygen species, excessive acidity may increase plasma instability and inhibit the reaction rate. Higher pH may make the environment too neutral or alkaline, leading to a decrease in the efficiency of reactive species generation and thus reducing the degradation rate. The mixed solution with pH 4 showed the best degradation effect. Acetic acid provides a moderately acidic environment, and peracetic acid, as a strong oxidant, can generate a large number of reactive oxides. These reactive oxides have the best reactivity under this environment and can effectively break the chemical bonds in PE molecules, promoting degradation.

[0122] Figure 6 The figures show the gas selectivity of different pH-based combustion aids for plasma degradation of waste plastics in Examples 1 and 11-15. The results indicate that as the pH of the combustion aid decreases, in addition to CO2 and H2, CO and CH4 are also produced as gaseous products. The optimal gaseous product distribution for plasma degradation of PE-4 was achieved when 50 μL of a mixture of acetic acid and peracetic acid at pH 4 was added. This is consistent with... Figure 5 Consistent.

[0123] Figure 7 The above are Raman spectroscopy plots of the products from plasma degradation of waste plastics in Examples 1 and 11-15 using combustion improvers with different pH values. Figure 7 It can be seen that as the pH of the combustion accelerator decreases, the ratio of the carbon G peak to the D peak gradually increases, indicating that the degraded carbon gradually transforms from amorphous to morphological. When 50 μL of combustion accelerator at pH 4 is added, the ratio of the G peak to the D peak corresponding to PE-4 reaches its maximum value, indicating that the solid of PE degraded by plasma forms crystalline carbon. This is consistent with SEM and XRD results. Figure 1 To.

[0124] Figure 8 The images shown are FTIR spectra of the products from plasma degradation of waste plastics in Examples 1 and 11-15 using combustion improvers with different pH values. Figure 8 It can be known that 3465cm -1 The position is a hydroxyl group, 1740cm -1 The position is an ester group, 1719 cm. -1 The position is a carbonyl group, 1630 cm. -1 The position is an aldehyde group, 1552cm -1 The position is a carboxyl group, 1170 and 1112 cm. -1 The position represents an ether bond. When 50 μL of combustion improvers at pH 7 and 9 are added, their corresponding values ​​are 1552 and 1112 cm⁻¹. -1 The peak disappeared and the other peaks were weak. As the pH gradually decreased, when the combustion accelerator was at pH 4 and 50 μL, all the peaks in PE-4 appeared and the intensity reached the maximum value. This indicates that the type and content of oxygen-containing functional groups affect the rate of plasma degradation of PE.

[0125] Figure 9 The diagram shows the water contact angle of the plasma-degraded waste plastic products in Examples 1 and 11-15 when different pH combustion aids were used. Figure 9 It can be seen that PE-4 has the lowest water contact angle (the size of the water contact angle is related to the type and content of oxygen-containing functional groups on the material surface; the smaller the value, the more oxygen-containing functional groups on the surface). Therefore, the plasma degradation ability of PE-4 is optimal, which is consistent with the FTIR diagram.

[0126] Figure 10 The above are gas chromatograms of the products from plasma degradation of waste plastics in Examples 1 and 11-15 using combustion improvers with different pH values. Figure 10 It can be seen that when the pH of the combustion improver is 7 and 9, its gas phase only contains H2 and CO2. As the pH gradually decreases, CO and CH4 appear in the gas phase. When the pH is 4, the gas phase of plasma degradation of PE-4 contains H2, CO, CH4, and CO2, respectively. This is consistent with... Figure 6 Consistent.

[0127] Example 16:

[0128] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0129] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0130] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 160 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled P-160.

[0131] Example 17:

[0132] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0133] (1) First, waste plastics are sorted to obtain 1 kg of polyethylene (PE) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are obtained by screening with an airflow sieve.

[0134] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with a pH of 4 and a combustion accelerant, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 10 mL / min into the reaction chamber containing the mixture (PE-4). Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The polyethylene under these conditions is labeled F-10.

[0135] Example 18:

[0136] A method for degrading waste plastics using plasma and the application of the degradation products, comprising the following steps:

[0137] (1) First, waste plastics are sorted to obtain 1 kg of epoxy resin (EP) waste plastics. Then, they are washed with deionized water and ethanol. Next, the washed PE is placed in a vacuum freeze dryer and dried at -60℃ for 24 hours. Then, it is preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. Then, the plastic particles are immersed in a stainless steel freeze tank containing liquid nitrogen for 20 minutes to embrittle. The plastic particles are further refined and crushed by an ultrasonic pulverizer. Finally, the microplastics with an average particle size of 120 μm are screened by an airflow sieve.

[0138] (2) Weigh 100 mg of pretreated epoxy resin (EP) microplastics and add them to the discharge reaction chamber. Simultaneously, add 50 μL of a mixed solution (acetic acid to peracetic acid volume ratio 2:1) with pH 4 as a combustion aid, ensuring thorough mixing until the mixture is moist. Then, introduce a mixed gas (30 vol% O2 and 70 vol% Ar) at a flow rate of 30 mL / min into the reaction chamber containing the mixture. Next, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gaseous products by plasma discharge treatment for 60 min. The epoxy resin under these conditions is labeled EP-4.

[0139] In summary, the raw materials used in this invention are readily available. The process of degrading microplastics using dielectric barrier discharge plasma is simple, efficient, environmentally friendly, and operates under mild reaction conditions (room temperature and pressure). It requires no catalyst and produces products with a clear distribution. Ultrasonic-assisted cryogenic pulverization technology breaks down waste plastics into microplastics, significantly increasing the reaction surface area. Combined with a mixed gas (oxygen and argon) and optimized combustion aids, highly efficient plastic degradation is achieved. The degradation products include high-value-added crystalline carbon, which can be used as a composite catalyst material, as well as gases used in various catalytic reactions. This invention offers significant advantages such as high degradation efficiency, low energy consumption, and wide application of the products, providing a new approach and method for turning waste plastics into valuable resources.

[0140] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for degrading waste plastics using plasma, characterized in that, Includes the following steps: 1) Pre-treating waste plastics to obtain microplastics; the pre-treatment includes: initial crushing to 10-30mm, liquid nitrogen embrittlement followed by ultrasonic refining and airflow sieving for particle size classification, wherein the particle size of the microplastics is 110-130μm; 2) The obtained microplastics are mixed with a combustion accelerant to wet the microplastics, and then reacted in a dielectric barrier discharge plasma environment to degrade the microplastics; when the pH of the combustion accelerant is acidic, the combustion accelerant is peracetic acid and / or acetic acid; when the pH of the combustion accelerant is neutral, the combustion accelerant is water; when the pH of the combustion accelerant is alkaline, the combustion accelerant is ammonia; the ratio of microplastics to combustion accelerant is 100-200 mg: 30-70 μL; the reaction is carried out under a mixed gas flow of argon and oxygen, and the volume ratio of argon to oxygen in the mixed gas flow is 80-50%: 20-50%; The degradation products of the waste plastic are one or more of solid crystalline carbon and gaseous substances such as H2, CO, CH4 and CO2.

2. The method for degrading waste plastics using plasma according to claim 1, characterized in that, The waste plastics include one or more of polyethylene, polypropylene, polyvinyl chloride, polystyrene, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyurethane, polyamide, and epoxy resin.

3. The method for degrading waste plastics using plasma according to claim 1, characterized in that, In the plasma environment described, the discharge power is 80-300W and the discharge frequency is 50-60Hz.

4. The method for degrading waste plastics using plasma according to claim 1, characterized in that, The reaction was carried out at room temperature and pressure for 5-180 minutes.

5. The method for degrading waste plastics using plasma according to claim 1, characterized in that, The total gas velocity of the mixed gas flow is 10-70 min / mL.

6. The application of a method for degrading waste plastics using plasma as described in any one of claims 1-5 in the field of solid waste treatment.

7. An application of a waste plastic degradation product in the field of catalysis, characterized in that, The waste plastic degradation products are obtained by the plasma degradation method as described in any one of claims 1-5.

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