Method for degrading waste plastics by using plasmas, application of method and application of plastic degradation product

Abstract

The invention belongs to the technical field of waste plastic treatment, and particularly relates to a method and application for degrading waste plastics through plasmas and application of plastic degradation products.The method comprises the following steps that 1, the waste plastics are pretreated, and micro-plastics are obtained; and 2) mixing the obtained micro-plastic with a combustion improver to wet the micro-plastic, and then reacting in a plasma environment to degrade the micro-plastic. Compared with the prior art, the method solves the problems of complicated operation, high cost, complicated product distribution, generation of toxic gas in a high-temperature environment and the like in the prior art, and realizes rapid degradation of the waste plastics under the conditions of normal temperature, normal pressure and no catalyst.

Description

Technical Field

[0001] The invention belongs to the technical field of waste plastic treatment, and specifically relates to a method and application of waste plastic degradation using plasma and application of plastic degradation products. Background Art

[0002] The rapid development and mass production of plastic products have brought great convenience to human life, but at the same time have caused serious harm to the human living environment. Due to the disadvantage that waste plastics are difficult to degrade, they cause soil and water pollution and pose a serious threat to animals and plants. In addition, plastic particles enter the human body through the food chain, posing a potential hazard to health. Therefore, how to effectively treat and utilize waste plastics and reduce their impact on the environment has become a key issue that needs to be solved urgently.

[0003] Traditional methods of waste plastic treatment, such as landfill and incineration, can reduce the amount of waste, but they also cause secondary pollution and energy waste, and cannot fundamentally solve the problem of plastic pollution. Considering that waste plastics are derived from fossil fuels, converting them into energy is a promising method that can not only reduce plastic emissions but also effectively protect existing fossil resources. Pyrolysis is the main method for plastic degradation. Although significant progress has been made in pyrolysis and gasification reaction parameters, catalysts, and process design in recent decades, the high endothermic performance of the degradation process requires higher energy input, which is the main obstacle to its economic benefits. In addition, low degradation efficiency, long processing time, large environmental impact, and the complexity of product distribution are another factor that limits the application of this method. In view of this situation, the development of new environmentally friendly and efficient waste plastic treatment technologies has become an important topic.

[0004] Low-temperature plasma has become a research hotspot in the field of waste plastic treatment due to its low macroscopic temperature and high particle energy. 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 a ZSM-5 catalyst, with an H2 production rate of 4.19 mmol / g, which improved the selectivity of benzene, toluene and xylene, while inhibiting the formation of wax. 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 effect of integrated pyrolysis and plasma catalytic reforming system on polyethylene (PE) degradation. The synergistic effect reached 250.98% at 500°C, and the total gas yield and H2 yield of plasma catalytic reforming PE were 146.5 and 102.52 mmol / g, respectively. Although the above-mentioned technologies have the required plastic degradation capacity, they are complicated to operate, cost-intensive, have complex product distribution, produce toxic gases in high temperature environment, and the catalyst synthesis and regeneration process are relatively cumbersome. In addition, the catalyst particles are easily aggregated and carbon deposition leads to their deactivation during the high temperature reaction, which are the key factors limiting their wide application.

[0005] Based on this, it is necessary to provide a method for treating waste plastics which is simple to handle, produces usable products and generates few pollutants. Summary of the invention

[0006] The purpose of the present invention is to solve at least one of the above problems and provide a method and application of using plasma to degrade waste plastics and the application of plastic degradation products, so as to solve the problems of complicated operation, high cost, complex product distribution, and generation of toxic gases in high temperature environment in the prior art. This scheme realizes the rapid degradation of waste plastics at normal temperature and pressure without catalyst.

[0007] The purpose of the present invention is achieved through the following technical solutions:

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

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

[0010] 2) The obtained microplastics are mixed with a combustion aid to wet the microplastics, and then reacted in a plasma environment to degrade the microplastics.

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

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

[0013] Further preferably, the number of washings with deionized water is 3-5 times, the concentration of ethanol is 95%, and the number of washings with ethanol is 3-5 times; the drying is carried out in a vacuum freeze dryer, the drying temperature is -50 to -70°C, the drying pressure is 1-10Pa, and the drying time is 20-24h; the power of the shear crusher is 0.2-0.4kW, and the crushing time is 30-50min; the liquid nitrogen cooling temperature is -100°C to -196°C, the cooling time is 10-30min, and the low-temperature resistant container is a stainless steel frozen storage tank; the power of the ultrasonic crusher is 0.5-2kW, the frequency of the ultrasonic crusher is 20-40kHz, and the crushing time is 20-40min; the power of the airflow screening machine is 0.75-7.5kW, and the mesh number of the stainless steel screen is 120-150 meshes.

[0014] Preferably, the dosage ratio of the microplastic to the combustion aid 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 improver is acidic, the combustion improver 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 improver is neutral, the combustion improver is water; when the pH of the combustion improver is alkaline, the combustion improver is aqueous ammonia.

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

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

[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 the present invention discloses an application of any of the above methods for degrading waste plastics using plasma in the field of solid waste treatment.

[0021] The third aspect of the present invention discloses an application of a waste plastic degradation product in the field of catalysis. The waste plastic degradation product is obtained by any of the above methods for degrading waste plastic using plasma. The waste plastic degradation product is solid crystalline carbon and one or more of the gases H2, CO, CH4 and CO2.

[0022] The invention relates to an efficient plasma degradation method for plastics, which is carried out under normal temperature and pressure conditions, reducing energy consumption and costs: first, ultrasonic-assisted low-temperature pulverization technology is used to process waste plastics into uniform microplastics, which significantly increases the surface area and enhances the contact efficiency with plasma. Then, a mixed gas of oxygen and argon is introduced to improve the degradation rate by optimizing the stability and oxidation reaction of the plasma. The use of a combustion aid further increases the degradation rate and promotes the conversion of microplastics into crystalline carbon and gas. Crystalline carbon can be used to prepare an efficient composite catalyst, and the gas product can be applied to thermal catalysis fields such as CO2 hydrogenation, CO hydrogenation and CH4 dry reforming. This method is not only efficient and environmentally friendly, but also simplifies the subsequent treatment process and improves resource utilization. Compared with the prior art, the present invention mainly solves the problem of rapidly degrading waste plastics at normal temperature and pressure without catalyst to obtain crystalline carbon and gas products. The present invention has significant energy-saving and environmentally friendly advantages in improving degradation rate, processing efficiency and resource utilization, and solves many key problems in traditional methods.

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

[0024] The present invention uses waste plastics as raw materials, and utilizes ultrasound-assisted low-temperature crushing technology and DBD plasma discharge to degrade microplastics to prepare crystalline carbon and gas products. The microplastics have a uniform particle shape and a large specific surface area, thereby improving their contact efficiency with the plasma. The process is simple, efficient, environmentally friendly, and has mild reaction conditions (normal temperature and pressure), and does not require a catalyst. The product distribution is simple, and the specific oxygen and argon mixed gas optimizes the stability of the plasma and the efficiency of the oxidation reaction. The use of a combustion aid further improves the degradation efficiency and promotes the conversion of microplastics into crystalline carbon and gas. The crystalline carbon can be used for carbon-based materials to prepare composite catalysts for application in the fields of photocatalysis, electrocatalysis and thermal catalysis, and the gas can be used in related thermal catalysis fields (such as CO2 hydrogenation, CO hydrogenation and CH4 dry reforming), which enables the recycling of waste plastics and has potential application prospects.

[0025] More specific:

[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 (normal temperature and pressure), applicable to mixed plastics, no need for catalysts, and faster and more efficient reaction process;

[0027] 2) The present 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 plasma to contact plastics more fully, which makes subsequent plasma treatment more efficient;

[0028] 3) In the process of plasma degradation of microplastics of the present invention, a gas mixture (oxygen and argon) is introduced. The gas mixture optimizes the stability and oxidation reaction of the plasma. 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 process of plasma degradation of microplastics of the present invention, a combustion aid (a mixture of acetic acid and peracetic acid, water or ammonia water) is added, and the best degradation environment is formed by optimizing different ratios and adjusting the pH. The combustion aid not only accelerates the degradation process, but also provides the best reaction environment through pH regulation, which increases the degradation rate by reducing the reaction energy barrier;

[0030] 5) The present invention utilizes plasma to degrade microplastics to obtain crystalline carbon and gas products, demonstrating the high efficiency and selectivity of the degradation process. The crystalline carbon can be used to prepare composite catalysts from carbon-based materials for application in photocatalysis, electrocatalysis and thermal catalysis, and the gas products can be applied in related thermal catalysis fields (such as CO2 hydrogenation, CO hydrogenation and CH4 dry reforming, etc.). BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a SEM image of the product after plasma degradation of waste plastics in Example 1, wherein a is PE that has not been degraded, and b is PE that has been degraded;

[0032] Figure 2 This is the XRD diagram of the product after plasma degradation of waste plastics in Example 1;

[0033] Figure 3 The figure is the effect of different proportions of combustion aids on the removal rate of waste plastics by plasma degradation in Examples 1-5;

[0034] Figure 4 The figure is 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 figure is the effect of different pH values ​​of the combustion aid on the removal rate of waste plastics by plasma degradation in Examples 1 and 11-15;

[0036] Figure 6 The gas selectivity diagram of the combustion aids with different pH values ​​for plasma degradation of waste plastics in Examples 1 and 11-15;

[0037] Figure 7 The Raman graphs of the products of waste plastics after plasma degradation when using combustion aids with different pH values ​​in Examples 1 and 11-15;

[0038] Figure 8 FTIR images of the products of waste plastics after plasma degradation when using combustion aids with different pH values ​​in Examples 1 and 11-15;

[0039] Fig. 9 The water contact angle diagram of the product after plasma degradation of waste plastics when using combustion aids with different pH values ​​in Examples 1 and 11-15;

[0040] Fig.10 The gas chromatograms of the products after plasma degradation of waste plastics when using combustion aids with different pH values ​​in Examples 1 and 11-15. DETAILED DESCRIPTION

[0041] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] In the following description, unless otherwise specified, the reagents used are conventional commercially available products, and the methods used are well 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: 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, then immerse the plastic particles in a low-temperature resistant container filled with liquid nitrogen to embrittle the plastic, then use an ultrasonic crusher to refine and crush the embrittled plastic particles, and finally use an airflow screening machine for particle size classification to obtain microplastics with a particle size of 110-130μm;

[0045] 2) The microplastics are placed in a plasma reactor, a combustion aid is added to make the microplastics reach a wet state, and then the mixture is reacted with plasma to obtain crystalline carbon and high value-added gas products.

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

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

[0048] Furthermore, in step 1), the power of the ultrasonic pulverizer is 0.5-2kW, the frequency of the ultrasonic pulverizer is 20-40kHz, and the pulverization time is 20-40min; the power of the airflow screening machine is 0.75-7.5kW, and the mesh number of the stainless steel screen is 120-150 meshes.

[0049] Furthermore, 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 a dielectric barrier discharge (DBD) plasma with a discharge power of 80-300 W and a discharge frequency of 50-60 Hz.

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

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

[0053] Furthermore, in step 2), the plasma reaction process is carried out in the state of adding a combustion aid. When the pH of the combustion aid 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 aid is equal to neutral (7), the combustion aid is water; when the pH of the combustion aid is alkaline (9), the combustion aid is ammonia water.

[0054] Furthermore, the volume ratio of the amount of microplastics to the combustion aid 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] The present invention uses waste plastics as raw materials, and utilizes ultrasound-assisted low-temperature crushing technology and DBD plasma discharge to degrade microplastics to prepare crystalline carbon and gas products. The microplastics have a uniform particle shape and a large specific surface area, thereby improving their contact efficiency with the plasma. The process is simple, efficient, environmentally friendly, and has mild reaction conditions (normal temperature and pressure), and does not require a catalyst. The product distribution is simple, and the specific oxygen and argon mixed gas optimizes the stability of the plasma and the efficiency of the oxidation reaction. The use of a combustion aid further improves the degradation efficiency and promotes the conversion of microplastics into crystalline carbon and gas. The crystalline carbon can be used for carbon-based materials to prepare composite catalysts for application in the fields of photocatalysis, electrocatalysis and thermal catalysis, and the gas can be used in related thermal catalysis fields (such as CO2 hydrogenation, CO hydrogenation and CH4 dry reforming), which enables the recycling of waste plastics and has potential application prospects.

[0057] Embodiment 1:

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

[0059] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0060] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) as a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 2HAc / 1PAA.

[0061] Figure 1 is the 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 long strips, which indicates that plasma treatment of PE-4 may change its surface structure and chemical properties, and then cause the PE-4 molecules to break and carbonize.

[0062] Figure 2 is the XRD diagram 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 about 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 of the polyethylene molecular chain.

[0063] Embodiment 2:

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

[0065] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0066] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber, and at the same time drop 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 0:1) as a combustion aid to fully mix them into a wet state, then introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4), then apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process, and finally obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 0HAc / 1PAA.

[0067] Embodiment 3:

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

[0069] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0070] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 1:2) as a combustion aid to fully mix them into a wet state. Then, introduce 30 mL / min of mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 minutes. The polyethylene under this condition is marked as 1HAc / 2PAA.

[0071] Embodiment 4:

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

[0073] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0074] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 1:1) as a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 1HAc / 1PAA.

[0075] Embodiment 5:

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

[0077] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0078] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber, and at the same time drop 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 1:0) as a combustion aid to fully mix them into a wet state, then introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4), then apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process, and finally obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 1HAc / 0PAA.

[0079] Figure 3 The figure is the effect of different proportions of the combustion aid on the removal rate of plasma degradation PE in Examples 1-5. Figure 3 It can be seen that when acetic acid is used alone, the degradation process is relatively slow due to the lack of sufficient oxidizing ability. When peracetic acid is used alone, although it has strong oxidizing ability, it lacks a proper acidic environment, resulting in instability of the plasma reaction, thereby reducing the overall degradation efficiency. When the combustion aid HAc:PAA=2:1, the removal ability of PE-4 is the largest 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 to accelerate the decomposition of PE.

[0080] Embodiment 6:

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

[0082] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0083] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) as a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (0 vol% O2 and 100 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. Polyethylene under this condition is marked as 0O2 / 100Ar.

[0084] Embodiment 7:

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

[0086] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0087] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (10 vol% O2 and 90 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 10O2 / 90Ar.

[0088] Embodiment 8:

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

[0090] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0091] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (20 vol% O2 and 80 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 20O2 / 80Ar.

[0092] Embodiment 9:

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

[0094] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0095] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (40 vol% O2 and 60 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 40O2 / 60Ar.

[0096] Embodiment 10:

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

[0098] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0099] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) as a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (50 vol% O2 and 50 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as 50O2 / 50Ar.

[0100] Figure 4 Graph showing the effect of different proportions of mixed gas on the removal rate of plasma degradation PE in Examples 1 and 6-10; Figure 4 It can be seen that in a single argon environment, although the plasma has good stability, it lacks sufficient oxidizing ability and the degradation rate is low. When the oxygen ratio is high, although the oxidizing ability increases, the stability of the plasma decreases, resulting in the degradation rate basically no longer increasing, and even instability may occur. When the gas ratio of oxygen to argon is 30vol% O2:70vol% Ar, the degradation rate reaches the best. At this ratio, the oxygen concentration is sufficient to generate enough active oxygen species to effectively degrade PE. At the same time, the high proportion of argon ensures the stability and uniformity of the plasma, thereby achieving efficient degradation.

[0101] Embodiment 11:

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

[0103] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0104] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture (volume ratio of acetic acid to peracetic acid 2:1) with a pH of 3.5 and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture. Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as PE-3.5.

[0105] Embodiment 12:

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

[0107] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0108] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 5 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture. Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as PE-5.

[0109] Embodiment 13:

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

[0111] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0112] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 6 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture. Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as PE-6.

[0113] Embodiment 14:

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

[0115] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0116] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of water combustion aid with a pH of 7 to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture. Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as PE-7.

[0117] Embodiment 15:

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

[0119] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0120] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of ammonia combustion aid with a pH of 9 to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture. Then, apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as PE-9.

[0121] Figure 5 The figure is the effect of different pH values ​​of the combustion aids on the removal rate of waste plastics by plasma degradation in Examples 1 and 11-15. Figure 5 It shows that although a lower pH value can also promote the generation of reactive oxygen species, excessive acidity may lead to increased plasma instability and inhibit the reaction rate. A higher pH value may make the environment too neutral or alkaline, resulting in a decrease in the efficiency of active species generation, thereby reducing the degradation rate. The mixed solution with a pH of 4 shows the best degradation effect. Acetic acid provides a moderately acidic environment, and peracetic acid, as a strong oxidant, can produce a large number of reactive oxides. These reactive oxides have the best reaction activity in this environment and can effectively break the chemical bonds in PE molecules and promote degradation.

[0122] Figure 6 The gas selectivity diagram of different pH combustion aids for plasma degradation of waste plastics in Examples 1 and 11-15 shows that as the pH of the combustion aid decreases, in addition to CO2 and H2, CO and CH4 will also be produced in the gas products. When 50 μL of a mixture of acetic acid and peracetic acid with a pH of 4 is added as a combustion aid, the distribution of gas products of plasma degradation of PE-4 reaches the best, which is also consistent with Figure 5 be consistent.

[0123] Figure 7 The Raman diagrams of the products of waste plastics after plasma degradation when using combustion aids of different pH in Examples 1 and 11-15 are shown in FIG. Figure 7 It can be seen that as the pH of the combustion aid decreases, the ratio of carbon G peak to D peak gradually increases, which indicates that the degraded carbon gradually changes from amorphous to morphological. When 50 μL of the combustion aid with a pH of 4 is added, the ratio of G peak to D peak corresponding to PE-4 reaches the maximum value, indicating that the solid of PE degraded by plasma forms crystalline carbon, which is consistent with the SEM and XRD Figure 1 To.

[0124] Figure 8 FTIR images of the products of waste plastics after plasma degradation using combustion aids of different pH values ​​in Examples 1 and 11-15. Figure 8 It can be seen that 3465cm -1 The hydroxyl group is at 1740 cm -1 The ester group is at 1719cm -1 The carbonyl group is at 1630 cm -1 Aldehyde group, 1552 cm -1 The carboxyl group is at 1170 and 1112 cm -1 When 50 μL of the combustion aid at pH 7 and 9 was added, their corresponding 1552 and 1112 cm -1 The peak at 4°C disappeared and the intensities of other peaks were weak. As the pH gradually decreased, when the pH was 4 and the combustion aid was 50 μL, all the peaks in PE-4 appeared and the intensity reached the maximum value, indicating that the type and content of oxygen-containing functional groups affect the rate of plasma degradation of PE.

[0125] Fig. 9 The water contact angle diagram of the product after plasma degradation of waste plastics when using different pH combustion aids in Examples 1 and 11-15, Fig. 9 It can be seen that the water contact angle of PE-4 is the lowest (the size of the water contact angle is related to the type and content of oxygen-containing functional groups on the surface of the material. The smaller the value, the more oxygen-containing functional groups on the surface). Therefore, the ability of plasma to degrade PE-4 is the best, which is consistent with the FTIR graph.

[0126] Fig.10 The gas chromatograms of the products of plasma degradation of waste plastics when using combustion aids of different pH values ​​in Examples 1 and 11-15 are shown in FIG. Fig.10 It can be seen that when the pH of the combustion aid is 7 and 9, their gas phases only have H2 and CO2. As the pH gradually decreases, CO and CH4 appear in the gas phase products. When the pH is 4, the gas phases of plasma degradation of PE-4 are H2, CO, CH4 and CO2, respectively. This is consistent with Figure 6 be consistent.

[0127] Embodiment 16:

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

[0129] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0130] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a voltage of 160 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as P-160.

[0131] Embodiment 17:

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

[0133] (1) First, waste plastics were sorted to obtain 1 kg of polyethylene (PE) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h. The PE was then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement. The plastic particles were further finely crushed with an ultrasonic pulverizer, and finally screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0134] (2) Weigh 100 mg of pretreated polyethylene (PE) microplastics and add them to the discharge reaction chamber. At the same time, add 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) as a combustion aid to mix them thoroughly and evenly until they are wet. Then, introduce 10 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture (PE-4). Then, apply a voltage of 200 W to the electrodes of the discharge reaction chamber to trigger the discharge process. Finally, crystalline carbon and gas products are obtained by plasma discharge treatment for 60 min. The polyethylene under this condition is marked as F-10.

[0135] Embodiment 18:

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

[0137] (1) First, waste plastics were sorted to obtain 1 kg of epoxy resin (EP) waste plastics, which were then washed with deionized water and ethanol. The washed PE was then placed in a vacuum freeze dryer and dried at -60°C for 24 h, and then preliminarily crushed to obtain plastic particles with a particle size of 10-30 mm. The plastic particles were then immersed in a stainless steel freezing tank filled with liquid nitrogen for 20 min of embrittlement, and further finely crushed with an ultrasonic pulverizer. Finally, the plastic particles were screened with an airflow sifter to obtain microplastics with an average particle size of 120 μm.

[0138] (2) Weigh 100 mg of pretreated epoxy resin (EP) microplastics and add them to the discharge reaction chamber, and at the same time drop 50 μL of a mixture of pH 4 (volume ratio of acetic acid to peracetic acid 2:1) and a combustion aid to fully mix them into a wet state, then introduce 30 mL / min of a mixed gas (30 vol% O2 and 70 vol% Ar) into the reaction chamber containing the mixture, then apply a 200 W voltage to the electrodes of the discharge reaction chamber to trigger the discharge process, and finally obtain crystalline carbon and gas products by plasma discharge treatment for 60 min. The epoxy resin under this condition is marked as EP-4.

[0139] In summary, the raw materials of the present invention are easy to obtain, and the process of degrading microplastics by dielectric barrier discharge plasma is simple, efficient, environmentally friendly, mild reaction conditions (normal temperature and pressure), and no catalyst is required, and the product distribution is concise; the waste plastics are crushed into microplastics by ultrasonic-assisted low-temperature crushing technology, which significantly increases the reaction specific surface area, and the mixed gas (oxygen and argon) and optimized combustion aid are combined to achieve efficient degradation of plastics; the degradation products include crystalline carbon with high added value, which can be used as a composite catalyst material, as well as gases for various catalytic reactions. The technology of the present invention has the significant advantages of high degradation efficiency, low energy consumption, and wide application of products, and provides new ideas and methods for turning waste plastics into treasures.

[0140] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and 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 present invention should be within the scope of protection of the present invention.

Claims

1. A method for degrading waste plastics using plasma, characterized in that: The steps include: 1) Pre-treating waste plastics to obtain microplastics; 2) The obtained microplastics are mixed with a combustion aid to wet the microplastics, and then reacted in a plasma environment to degrade the microplastics.

2. The method for degrading waste plastics using plasma according to claim 1, characterized in that: The pretreatment includes preliminary crushing, fine crushing and particle size classification, and the particle size of the microplastics is 110-130μm.

3. The method for degrading waste plastics using plasma according to claim 1, characterized in that: The dosage ratio of the microplastic to the combustion aid is 100-200 mg: 30-70 μL.

4. 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.

5. The method for degrading waste plastics using plasma according to claim 1, characterized in that: When the pH of the combustion improver is acidic, the combustion improver is peracetic acid and / or acetic acid; when the pH of the combustion improver is neutral, the combustion improver is water; when the pH of the combustion improver is alkaline, the combustion improver is ammonia water.

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

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

8. The method for degrading waste plastics using plasma according to claim 1, characterized in that: The reaction is carried out under a certain gas flow, which is argon and / or oxygen, and the total gas velocity is 10-70 min / mL.

9. Use of the method for degrading waste plastics using plasma as claimed in any one of claims 1 to 8 in the field of solid waste treatment.

10. An application of waste plastic degradation products in the field of catalysis, characterized in that: The waste plastic degradation product is obtained by the method for degrading waste plastic using plasma as described in any one of claims 1 to 8, and the waste plastic degradation product is solid crystalline carbon and one or more of the gases H2, CO, CH4 and CO2.

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