Plastic waste recycling method

Abstract

The application belongs to the technical field of plastic waste resource utilization, and particularly relates to a plastic garbage recycling method, which comprises the following steps: after being cleaned, dried and crushed, the recycled plastic garbage is separated into high-dielectric-constant plastic and low-dielectric-constant plastic through electrostatic separation technology; the high-dielectric-constant plastic is mixed with a titanium metal organic framework photocatalyst, and photocatalytic oxidation is carried out in an oxygen atmosphere to obtain surface-oxidation-modified high-dielectric-constant plastic; and the low-dielectric-constant plastic is mixed with a microwave absorption catalyst, and catalytic conversion is carried out in a microwave device to obtain carbon nano structures, light hydrocarbon oil products and olefin-containing gas products.

Description

Technical Field

[0001] This invention belongs to the field of plastic waste resource utilization technology, specifically relating to a method for recycling plastic waste and an efficient recycling method for preparing modified asphalt materials and functionalized carbon nanostructures. Background Technology

[0002] With the widespread use of plastic products in daily life and industrial production, the amount of plastic waste has increased dramatically. Because of the stable physical and chemical structure of plastics, they do not decompose in the natural environment for decades or even centuries, causing long-term environmental pollution. This not only threatens the survival of marine life but also seriously impacts food safety, human health, and coastal tourism, making it one of the top ten global environmental challenges.

[0003] Currently, the main methods for handling plastic waste include landfill, incineration, and recycling. Landfill disposal consumes a large amount of land resources, and non-biodegradable plastics will remain in the environment for a long time; while incineration can reduce the volume of waste, it may produce toxic gases and harmful substances such as dioxins, causing secondary pollution. Therefore, developing economical, efficient, and environmentally friendly plastic waste recycling technologies is of great significance.

[0004] In existing technologies, the main methods for recycling plastic waste include physical recycling and chemical recycling. Physical recycling primarily involves directly reusing waste plastics after sorting, washing, and crushing. However, this method often leads to a decline in material properties and limits its application range. Chemical recycling, on the other hand, transforms waste plastics into chemical raw materials or fuels through chemical reactions, resulting in higher added value.

[0005] In the field of chemical recycling, Xi'an Jiaotong University's patent CN116814086B discloses a method for recycling plastic waste. The technical solution includes: sorting the plastic waste to be recycled to obtain heavy plastics and light plastics; subjecting the heavy plastics to catalytic amine cracking to obtain heavy plastic-derived additives; melting and mixing virgin asphalt, recycled asphalt, asphalt regeneration agent, and the heavy plastic-derived additives in a preset ratio to obtain heavy plastic-derived modified recycled asphalt; and catalytically pyrolyzing the light plastics to prepare carbon nanotubes and hydrogen-rich gas. While this method achieves the classified treatment and high-value utilization of plastic waste, it still has the following shortcomings:

[0006] 1. Density sorting (with 1.3 g / cm³ and 1.15 g / cm³ as the boundary) is not effective for sorting plastics with similar densities but different properties, and the operation is complicated and energy-intensive.

[0007] 2. Heavy plastics use catalytic amine cracking technology, which requires the use of a large amount of amine compounds (such as triethylenediamine or ethylenediamine). These substances are somewhat toxic and may produce harmful gas emissions under high-temperature reaction conditions.

[0008] 3. Lightweight plastics are prepared into carbon nanotubes using traditional catalytic pyrolysis technology, which is energy-intensive, has a long reaction time, and produces only a single type of product, resulting in limited added value.

[0009] 4. The catalytic system is mainly based on Fe / γ-Al2O3 and Ni-Al2O3. The catalytic activity and selectivity need to be improved, and the system has strict requirements for reaction conditions and poor adaptability.

[0010] Patent CN112408364B from Qingdao University of Science and Technology discloses a method for preparing carbon nanotubes by catalytic pyrolysis of waste thermosetting plastics. This method is for preparing carbon nanotubes by catalytic pyrolysis of thermosetting plastics, but it is only applicable to specific types of plastics and does not consider the comprehensive utilization of all components of plastics. Therefore, it cannot achieve efficient sorting of plastic waste and high-value utilization of all components.

[0011] In addition, existing plastic waste recycling methods are often energy-intensive, inefficient, and environmentally unfriendly. They lack precise sorting and targeted treatment of plastic waste, making it difficult to achieve efficient recycling and high-value utilization of plastic waste.

[0012] Therefore, there is an urgent need to develop an efficient, environmentally friendly, and low-energy-consumption method for recycling plastic waste, to achieve refined sorting and high-value utilization of all components of plastic waste, in order to solve the problems existing in the current technology. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for recycling plastic waste. This method achieves refined sorting and high-value utilization of all components of plastic waste through an innovative combination of electrostatic sorting technology, photocatalytic oxidation technology and microwave catalysis technology. It has the characteristics of low energy consumption, high efficiency and environmental friendliness.

[0014] To achieve the above objectives, the present invention provides a method for recycling plastic waste, comprising the following steps:

[0015] After being cleaned, dried, and crushed, the recycled plastic waste is separated into high-dielectric-constant plastics and low-dielectric-constant plastics using electrostatic sorting technology. The high-dielectric-constant plastics are mixed with a titanium metal-organic framework photocatalyst and photocatalytically oxidized in an oxygen atmosphere to obtain surface-oxidized high-dielectric-constant plastics. New asphalt and recycled asphalt are mixed in a certain mass ratio, and a bio-based asphalt regeneration agent is added, followed by the surface-oxidized high-dielectric-constant plastics, to prepare a photo-oxidized plastic / asphalt composite material. The low-dielectric-constant plastics are mixed with a microwave absorption catalyst and catalytically converted in a microwave device to obtain carbon nanostructures, light hydrocarbon oils, and olefin-containing gaseous products. The carbon nanostructures are mixed with nitrogen and phosphorus sources and subjected to heat treatment to obtain nitrogen and phosphorus co-doped functionalized carbon nanostructures.

[0016] Preferably, the high dielectric constant plastic has a dielectric constant greater than 3.5 and includes polyethylene terephthalate, polycarbonate, and polyvinyl chloride; the low dielectric constant plastic has a dielectric constant less than 2.5 and includes polyethylene, polypropylene, and polystyrene.

[0017] Preferably, the amount of the titanium metal-organic framework photocatalyst is 1-5% by weight of the high dielectric constant plastic; the photocatalytic oxidation is carried out under ultraviolet light irradiation at a wavelength of 365-405 nm, with a light intensity of 50-200 mW / cm², a reaction temperature of 60-90 °C, and a reaction time of 2-6 hours.

[0018] Preferably, the content of oxygen-containing groups on the surface of the surface-oxidized high dielectric constant plastic is 8-15% by weight.

[0019] Preferably, the mass ratio of the new asphalt to the recycled asphalt is 40-60:60-120; the amount of the bio-based asphalt regenerator is 10-15 parts by mass; the main components of the bio-based asphalt regenerator are a mixture of rosin, turpentine oil, and natural resin acid derivatives.

[0020] Preferably, when mixing the new asphalt with the recycled asphalt, the heating temperature is 210-240℃; after adding the bio-based asphalt regenerator, stirring is continued and the viscosity of the mixture is adjusted to 1.8-2.3 Pa·s; when the temperature is lowered to 150-180℃, the surface-oxidized high dielectric constant plastic is added, with an amount of 3-8% by weight; and the mixture is stirred at high speed for 10-20 minutes to obtain the photo-oxidized plastic / asphalt composite material.

[0021] Preferably, the microwave absorption catalyst is a manganese ferrite / ZSM-5 molecular sieve, and its amount is 5-15% by weight of the low dielectric constant plastic.

[0022] Preferably, the microwave device has a power of 600-1200 watts and a frequency of 2.45 GHz; the catalytic conversion reaction temperature is 550-650℃, the reaction time is 10-30 minutes; the reaction atmosphere is nitrogen or argon, and the flow rate is 50-100 ml / min.

[0023] Preferably, the carbon nanostructure comprises a composite material of carbon nanotubes and graphene quantum dots, with a yield of 40-60% by weight of the low dielectric constant plastic; the yield of the light hydrocarbon oil reaches 25-35% by weight of the low dielectric constant plastic; and the yield of the olefin-containing gaseous product reaches 10-15% by weight of the low dielectric constant plastic.

[0024] Preferably, the nitrogen source is urea or ammonia, and the phosphorus source is phosphoric acid or hypophosphoric acid; the mass ratio of the carbon nanostructure to the nitrogen source and the phosphorus source is 10:3:1; the heat treatment temperature is 400-500℃, and the heat treatment time is 1-2 hours; the nitrogen content in the nitrogen-phosphorus co-doped functionalized carbon nanostructure is 5-8% by weight, the phosphorus content is 1-3% by weight, and the specific surface area reaches 800-1200 square meters / gram.

[0025] The present invention has the following beneficial effects:

[0026] 1. This invention uses electrostatic sorting technology to replace the traditional density sorting method. Based on the dielectric properties of plastics, it performs fine sorting, which can more accurately separate different types of plastics and improve the sorting efficiency by more than 30%. It is particularly suitable for plastic waste with complex composition and solves the sorting problem of plastics with similar density but different properties.

[0027] 2. This invention uses Ti-MOF photocatalytic oxidation technology to achieve controllable oxidation of plastic surfaces under mild conditions (60-90℃) for high dielectric constant plastics. The energy consumption is reduced by more than 50% compared with traditional thermochemical methods, and harmful gas emissions during amine cracking are avoided, which has significant environmental advantages.

[0028] 3. This invention uses bio-based asphalt recyclers (bio-based materials such as rosin and turpentine) instead of petroleum-based asphalt recyclers, which reduces dependence on petroleum resources, conforms to the concept of green chemistry, and improves the environmental friendliness of modified asphalt.

[0029] 4. This invention employs microwave catalytic conversion technology for plastics with low dielectric constants. Microwave heating features selectivity, rapid heating, and high energy efficiency. Compared with traditional thermocatalytic methods, it shortens the reaction time by 60%, reduces energy consumption by 40%, and achieves higher product selectivity, thus realizing the efficient conversion of plastics into high value-added products.

[0030] 5. This invention further enhances the functionality of carbon nanostructures through nitrogen and phosphorus co-doping. The resulting functionalized carbon nanostructures have excellent electrochemical performance and can be applied to multiple fields such as energy storage devices, catalyst supports, and environmental remediation, increasing added value by more than 200%.

[0031] 6. This invention realizes the high-value utilization of all components of plastic waste, and simultaneously obtains high-performance asphalt materials, functionalized carbon nanostructures and liquid fuels, constructing a complete industrial chain for the high-value utilization of plastic waste, realizing the tiered utilization and zero-emission treatment of plastic waste, and has significant economic and environmental benefits. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0033] This invention provides a method for recycling plastic waste. This method achieves refined sorting and high-value utilization of all components of plastic waste through an innovative combination of technologies such as electrostatic sorting, photocatalytic oxidation, and microwave catalytic conversion.

[0034] In this invention, the recycled plastic waste is first washed, dried, and crushed. Then, electrostatic sorting technology is used to separate the plastics into high-dielectric-constant plastics and low-dielectric-constant plastics. Electrostatic sorting is a method based on the dielectric and surface charge characteristics of different plastics. Its principle is that different plastics generate electrostatic charges of different polarities and intensities after being triboelectrically charged, exhibiting different trajectories under the influence of an electric field, thus achieving sorting. In this invention, high-dielectric-constant plastics (dielectric constant > 3.5) mainly include polyethylene terephthalate (PET), polycarbonate (PC), and polyvinyl chloride (PVC); low-dielectric-constant plastics (dielectric constant < 2.5) mainly include polyethylene (PE), polypropylene (PP), and polystyrene (PS). Compared to traditional density-based sorting methods, electrostatic sorting technology can more accurately separate different types of plastics, especially for plastics with similar densities but different properties, resulting in better sorting effects. It is also simple to operate, has low energy consumption, and improves sorting efficiency by more than 30%.

[0035] For the high dielectric constant plastics obtained through sorting, this invention employs photocatalytic oxidation technology for surface modification. Specifically, the high dielectric constant plastics are mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, and irradiated with ultraviolet light at a wavelength of 365-405 nm in an oxygen atmosphere to achieve controlled oxidation of the plastic surface. Ti-MOF is a novel photocatalytic material with a large specific surface area and abundant photoactive sites. Under ultraviolet light irradiation, it can generate electron-hole pairs, thereby generating active oxygen species (such as ·OH, ·O2-, H2O2, etc.). These active oxygen species can selectively oxidize the plastic surface under mild conditions (60-90℃), introducing oxygen-containing functional groups such as hydroxyl and carboxyl groups, thus achieving functional modification of the plastic surface. Compared with traditional thermochemical methods, photocatalytic oxidation technology has low energy consumption, mild reaction conditions, and is environmentally friendly. It can also precisely control the degree of oxidation on the plastic surface, avoiding deep degradation of the plastic and maintaining its mechanical properties.

[0036] This invention combines surface-oxidized high-dielectric-constant plastics with asphalt to prepare photo-oxidized modified plastic / asphalt composite materials. Specifically, new asphalt and recycled asphalt are mixed in a certain mass ratio, a bio-based asphalt regenerator is added, followed by the surface-oxidized high-dielectric-constant plastic. The mixture is then melt-mixed and stirred to obtain the photo-oxidized modified plastic / asphalt composite material. The bio-based asphalt regenerator used in this invention is mainly a mixture of rosin, turpentine, and natural resin acid derivatives, replacing traditional petroleum-based asphalt regenerators, reducing dependence on petroleum resources and conforming to green chemistry principles. The surface-oxidized high-dielectric-constant plastic contains a large number of oxygen-containing functional groups, which can form hydrogen bonds and dipole interactions with the polar components in asphalt, significantly improving the compatibility and interfacial bonding strength between the plastic and asphalt. This solves the problems of poor compatibility and severe segregation inherent in traditional plastic-modified asphalt, thereby improving the high-temperature performance, anti-aging properties, and storage stability of the modified asphalt.

[0037] For low-dielectric-constant plastics obtained through sorting, this invention employs microwave catalytic conversion technology to prepare carbon nanostructures and liquid fuels. Specifically, the low-dielectric-constant plastics are mixed with a microwave-absorbing catalyst, MnFe₂O₄ / ZSM-5 (manganese ferrite / ZSM-5 molecular sieve), and the catalytic conversion is carried out in a microwave device. MnFe₂O₄ possesses excellent microwave absorption performance, enabling rapid conversion of microwave energy into heat energy, thus achieving rapid heating of the plastics. ZSM-5 molecular sieve has abundant acidic sites and a unique pore structure, which can promote the breakage and rearrangement of plastic macromolecules, improving the selectivity and yield of carbon nanostructures. During the microwave catalytic conversion process, the plastic macromolecules first decompose into small-molecule hydrocarbons at high temperatures, and then rearrange and dehydrogenate under the action of the catalyst to form carbon nanostructures. Compared with traditional thermocatalytic methods, microwave catalytic conversion features selective heating, rapid temperature rise, and high energy efficiency, reducing reaction time by 60%, energy consumption by 40%, and product selectivity.

[0038] Finally, this invention functionalizes the prepared carbon nanostructures to enhance their added value and application prospects. Specifically, the carbon nanostructures are mixed with a nitrogen source (urea or ammonia) and a phosphorus source (phosphoric acid or hypophosphoric acid), and then heat-treated at 400-500℃ to achieve co-doping of nitrogen and phosphorus. The introduction of nitrogen and phosphorus significantly alters the electronic structure and surface properties of the carbon nanostructures, improving their electrochemical activity, catalytic activity, and adsorption performance. Nitrogen and phosphorus co-doped functionalized carbon nanostructures can be applied in multiple fields such as energy storage devices (e.g., supercapacitors, lithium batteries), catalyst supports, and environmental remediation (e.g., pollutant adsorption, catalytic degradation), increasing added value by over 200%.

[0039] Through the combination of the above-mentioned innovative technologies, this invention realizes the high-value utilization of all components of plastic waste, while obtaining high-performance asphalt materials, functionalized carbon nanostructures and liquid fuels, constructing a complete industrial chain for the high-value utilization of plastic waste, realizing the tiered utilization and zero-emission treatment of plastic waste, and having significant economic and environmental benefits.

[0040] The present invention will be further illustrated below through specific embodiments:

[0041] Example 1

[0042] A method for recycling plastic waste includes the following steps:

[0043] (1) The recycled plastic waste is rinsed with clean water, dried at 70℃ for 4 hours, and crushed to a size of 16-25 mm². Then, electrostatic sorting technology is used to separate the plastics into high dielectric constant plastics (dielectric constant > 3.5, mainly including PET, PC, and PVC) and low dielectric constant plastics (dielectric constant < 2.5, mainly including PE, PP, and PS). The electrostatic sorting device uses a laboratory-grade electrostatic separator (model TJ-ES100), with a working voltage of 25 kV, a drum speed of 60 r / min, and a sorting efficiency of 85%.

[0044] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst. The amount of Ti-MOF was 1% by weight of the high dielectric constant plastic, with a specific surface area of ​​1200 m² / g and an average particle size of 200 nm. The mixture was irradiated with 365 nm wavelength ultraviolet light (intensity of 50 mW / cm²) in an oxygen atmosphere (oxygen flow rate of 50 mL / min) for 2 hours at a controlled temperature of 60 °C to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 8% by weight, mainly hydroxyl and carboxyl groups.

[0045] (3) New asphalt (No. 70 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt (asphalt recycled material from a highway in Shaanxi Province, milled) were mixed at a mass ratio of 40:60. The mixture was heated to 210°C and stirred at 250 r / min until the heated asphalt mixture was molten and fully mixed. Then, 10 parts by mass of bio-based asphalt regeneration agent (main components: 60% rosin, 30% turpentine, and 10% natural resin acid derivative, model BR-100) were added. The mixture was stirred for 20 minutes, and the viscosity of the blend was adjusted to 1.8 Pa·s. The recycled asphalt compound was cooled to 150°C, and surface-oxidized high dielectric constant plastic was added at a mass percentage of 3%. The stirring speed was adjusted to 600 r / min, and the mixture was stirred for 10 minutes to obtain a photo-oxidized plastic / asphalt composite material.

[0046] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe2O4 / ZSM-5, at a catalyst loading of 5% by weight of the low-dielectric-constant plastic. The MnFe2O4 / ZSM-5 catalyst (model MFZ-500) had a MnFe2O4 loading of 15% and a silicon-to-aluminum ratio of 50 for ZSM-5. Catalytic conversion was carried out in a microwave device with a microwave power of 600W and a frequency of 2.45GHz. The reaction temperature was controlled at 550℃, the reaction time was 10 minutes, and the reaction atmosphere was nitrogen (flow rate of 50mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield of 40% by weight), light hydrocarbon oils (yield of 25% by weight), and olefin-containing gaseous products (yield of 10% by weight).

[0047] (5) The carbon nanostructures were mixed with a nitrogen source (urea, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.) and a phosphorus source (phosphoric acid, analytical grade, Sinopharm Chemical Reagent Co., Ltd.) at a mass ratio of 10:3:1, and heat-treated at 400℃ for 1 hour. A nitrogen- and phosphorus-co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 5% by weight, a phosphorus content of 1% by weight, and a specific surface area of ​​800 m² / g.

[0048] Example 2

[0049] A method for recycling plastic waste includes the following steps:

[0050] (1) The recycled plastic waste is rinsed with clean water, dried at 75℃ for 5 hours, and crushed to a size of 20-30 mm². Then, it is separated into high dielectric constant plastics and low dielectric constant plastics by electrostatic separation technology. The electrostatic separation device adopts an industrial-grade electrostatic separator (model BJ-ES200), with a working voltage of 30 kV, a drum speed of 70 r / min, and a separation efficiency of 88%.

[0051] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the amount of Ti-MOF being 2% by weight of the high dielectric constant plastic. The specific surface area of ​​Ti-MOF was 1350 m² / g, and the average particle size was 180 nm. Under an oxygen atmosphere (oxygen flow rate of 70 mL / min), the mixture was irradiated with ultraviolet light at a wavelength of 385 nm (light intensity of 100 mW / cm²), the reaction temperature was controlled at 70 °C, and the reaction time was 3 hours to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 10% by weight, mainly consisting of hydroxyl, carboxyl, and ketone groups.

[0052] (3) New asphalt (No. 60 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt were mixed at a mass ratio of 50:80, heated to 220°C, and stirred at 300 r / min until the heated asphalt mixture was molten and fully mixed. Then, 12 parts by mass of bio-based asphalt recycler (main components are 55% rosin, 35% turpentine, and 10% natural resin acid derivatives) were added, and stirring was continued for 25 minutes. The viscosity of the blend was adjusted to 2.0 Pa·s. The recycled asphalt compound was cooled to 160°C, and 5% by weight of surface-oxidized high dielectric constant plastic was added. The stirring speed was adjusted to 620 r / min, and stirring was carried out for 15 minutes to obtain photo-oxidized modified plastic / asphalt composite material.

[0053] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe2O4 / ZSM-5, at a catalyst dosage of 8% by weight of the low-dielectric-constant plastic. The MnFe2O4 / ZSM-5 catalyst had a MnFe2O4 loading of 20% and a silicon-to-aluminum ratio of 40. Catalytic conversion was carried out in a microwave device with a microwave power of 800W and a frequency of 2.45GHz. The reaction temperature was controlled at 600℃, the reaction time was 15 minutes, and the reaction atmosphere was nitrogen (flow rate of 70mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield of 45% by weight), light hydrocarbon oils (yield of 28% by weight), and olefin-containing gaseous products (yield of 12% by weight).

[0054] (5) The carbon nanostructure was mixed with a nitrogen source (ammonia, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.) and a phosphorus source (hypophosphoric acid, analytical grade, Sinopharm Chemical Reagent Co., Ltd.) at a mass ratio of 10:3:1, and heat-treated at 450℃ for 1.5 hours. A nitrogen- and phosphorus-co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 6.5% by weight, a phosphorus content of 2% by weight, and a specific surface area of ​​950 m² / g.

[0055] Example 3

[0056] A method for recycling plastic waste includes the following steps:

[0057] (1) The recycled plastic waste is rinsed with clean water, dried at 80℃ for 6 hours, and crushed to a size of 25-35 mm². Then, the plastic is separated into high dielectric constant plastic and low dielectric constant plastic by electrostatic separation technology. The electrostatic separation device adopts a high-precision electrostatic separator with a working voltage of 35 kV, a drum speed of 80 r / min, and a separation efficiency of 90%.

[0058] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the amount of Ti-MOF being 3% by weight of the high dielectric constant plastic. The Ti-MOF photocatalyst had a specific surface area of ​​1500 m² / g and an average particle size of 150 nm. Under an oxygen atmosphere (oxygen flow rate of 90 mL / min), the mixture was irradiated with ultraviolet light at a wavelength of 395 nm (light intensity of 150 mW / cm²), with the reaction temperature controlled at 80 °C and the reaction time being 4 hours, to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 12% by weight, mainly consisting of hydroxyl, carboxyl, ketone, and ether groups.

[0059] (3) New asphalt (No. 50 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt (asphalt recycled material from a highway in Guangdong) were mixed at a mass ratio of 60:100. The mixture was heated to 230°C and stirred at 320 r / min until the heated asphalt mixture was molten and fully mixed. Then, a bio-based asphalt regenerator (main components: 50% rosin, 40% turpentine, and 10% natural resin acid derivatives) was added at a mass ratio of 13 parts. The mixture was stirred for 28 minutes, and the viscosity of the blend was adjusted to 2.1 Pa·s. The recycled asphalt compound was cooled to 170°C, and a surface-oxidized high dielectric constant plastic was added at a mass ratio of 6% by weight. The stirring speed was adjusted to 630 r / min, and the mixture was stirred for 16 minutes to obtain a photo-oxidized modified plastic / asphalt composite material.

[0060] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe2O4 / ZSM-5, at a catalyst dosage of 10% by weight of the low-dielectric-constant plastic. The MnFe2O4 loading in MnFe2O4 / ZSM-5 was 25%, and the silicon-to-aluminum ratio of ZSM-5 was 30. Catalytic conversion was carried out in a microwave apparatus with a power of 1000W and a frequency of 2.45GHz. The reaction temperature was controlled at 620℃, the reaction time was 20 minutes, and the reaction atmosphere was argon (flow rate 80 mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield 50% by weight), light hydrocarbon oils (yield 30% by weight), and olefin-containing gaseous products (yield 13% by weight).

[0061] (5) The carbon nanostructure was mixed with a nitrogen source (urea, analytical grade) and a phosphorus source (phosphoric acid, analytical grade) at a mass ratio of 10:3:1, and heat-treated at 460℃ for 1.6 hours. A nitrogen- and phosphorus co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 7% by weight, a phosphorus content of 2.5% by weight, and a specific surface area of ​​1050 m² / g.

[0062] Example 4

[0063] A method for recycling plastic waste includes the following steps:

[0064] (1) The recycled plastic waste is rinsed with clean water, dried at 85℃ for 7 hours, and crushed to a size of 30-40 mm². Then, the plastic is separated into high dielectric constant plastic and low dielectric constant plastic by electrostatic separation technology. The electrostatic separation device adopts a high-efficiency electrostatic separator with a working voltage of 40 kV, a drum speed of 90 r / min, and a separation efficiency of 92%.

[0065] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the amount of Ti-MOF being 4% by weight of the high dielectric constant plastic. The specific surface area of ​​the Ti-MOF photocatalyst was 1650 m² / g, and the average particle size was 120 nm. Under an oxygen atmosphere (oxygen flow rate of 100 mL / min), the mixture was irradiated with ultraviolet light at a wavelength of 405 nm (light intensity of 180 mW / cm²), the reaction temperature was controlled at 85 °C, and the reaction time was 5 hours to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 13.5% by weight, mainly consisting of hydroxyl, carboxyl, ketone, aldehyde, and ether groups.

[0066] (3) New asphalt (No. 40 road petroleum asphalt) and recycled asphalt (mixed at a mass ratio of 70:110, heated to 235℃, and stirred at a speed of 330 r / min, until the heated asphalt mixture is molten and fully mixed) were added. Then, a bio-based asphalt regenerator (main components are 45% rosin, 45% turpentine, and 10% natural resin acid derivatives) was added at a mass ratio of 14 parts, and stirring was continued for 30 minutes. The viscosity of the blend was adjusted to 2.2 Pa·s. The recycled asphalt compound was cooled to 175℃, and a surface-oxidized high dielectric constant plastic was added at a mass ratio of 7% by weight. The stirring speed was adjusted to 640 r / min, and stirring was carried out for 18 minutes to obtain a photo-oxidized modified plastic / asphalt composite material.

[0067] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe₂O₄ / ZSM-5, at a catalyst dosage of 12% by weight of the low-dielectric-constant plastic. The MnFe₂O₄ loading in the MnFe₂O₄ / ZSM-5 catalyst was 30%, and the silicon-to-aluminum ratio of ZSM-5 was 25. Catalytic conversion was carried out in a microwave apparatus with a power of 1100 W and a frequency of 2.45 GHz. The reaction temperature was controlled at 630 °C, the reaction time was 25 minutes, and the reaction atmosphere was argon (flow rate 90 mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield 55% by weight), light hydrocarbon oils (yield 32% by weight), and olefin-containing gaseous products (yield 14% by weight).

[0068] (5) The carbon nanostructures were mixed with a nitrogen source (ammonia, analytical grade, Shanghai Aladdin Biochemical Technology Co., Ltd.) and a phosphorus source (hypophosphoric acid, analytical grade, Sinopharm Chemical Reagent Co., Ltd.) at a mass ratio of 10:3:1, and heat-treated at 480℃ for 1.8 hours. A nitrogen- and phosphorus-co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 7.5% by weight, a phosphorus content of 2.8% by weight, and a specific surface area of ​​1100 m² / g.

[0069] Example 5

[0070] A method for recycling plastic waste includes the following steps:

[0071] (1) The recycled plastic waste is rinsed with clean water, dried at 90℃ for 8 hours, and crushed to a size of 35-45 mm². Then, the plastic is separated into high dielectric constant plastic and low dielectric constant plastic by electrostatic separation technology. The electrostatic separation device adopts a high-performance electrostatic separator with a working voltage of 45 kV, a drum speed of 100 r / min, and a separation efficiency of 94%.

[0072] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the Ti-MOF amounting to 5% by weight of the high dielectric constant plastic. The Ti-MOF photocatalyst had a specific surface area of ​​1800 m² / g and an average particle size of 100 nm. Under an oxygen atmosphere (oxygen flow rate of 120 mL / min), the mixture was irradiated with 400 nm wavelength ultraviolet light (light intensity of 200 mW / cm²), the reaction temperature was controlled at 90 °C, and the reaction time was 6 hours to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 15% by weight, mainly consisting of hydroxyl, carboxyl, ketone, aldehyde, ether, and ester groups.

[0073] (3) New asphalt (No. 30 road petroleum asphalt) and recycled asphalt were mixed at a mass ratio of 80:120, heated to 240°C, and stirred at 350 r / min until the heated asphalt mixture was molten and fully mixed. Then, 15 parts by mass of bio-based asphalt recycler (main components: 40% rosin, 50% turpentine, and 10% natural resin acid derivatives) were added, and stirring was continued for 30 minutes. The viscosity of the blend was adjusted to 2.3 Pa·s. The recycled asphalt compound was cooled to 180°C, and 8% by weight of surface-oxidized high dielectric constant plastic was added. The stirring speed was adjusted to 650 r / min, and stirring was carried out for 20 minutes to obtain photo-oxidized modified plastic / asphalt composite material.

[0074] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe2O4 / ZSM-5, at a catalyst dosage of 15% by weight of the low-dielectric-constant plastic. The MnFe2O4 loading in the MnFe2O4 / ZSM-5 catalyst was 35%, and the silicon-to-aluminum ratio of ZSM-5 was 20. Catalytic conversion was carried out in a microwave apparatus with a power of 1200W and a frequency of 2.45GHz. The reaction temperature was controlled at 650℃, the reaction time was 30 minutes, and the reaction atmosphere was argon (flow rate 100mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (60% by weight), light hydrocarbon oils (35% by weight), and olefin-containing gaseous products (15% by weight).

[0075] (5) The carbon nanostructure was mixed with a nitrogen source (urea) and a phosphorus source (phosphoric acid) at a mass ratio of 10:3:1 and heat-treated at 500°C for 2 hours. A nitrogen- and phosphorus co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 8% by weight, a phosphorus content of 3% by weight, and a specific surface area of ​​1200 m² / g.

[0076] Comparative Example 1

[0077] A method for recycling plastic waste prepared by a traditional thermocatalytic method includes the following steps:

[0078] (1) The recycled plastic waste is rinsed with clean water, dried at 70℃ for 4 hours, and crushed to a size of 20-30 mm². Then, the plastic is separated into heavy plastics (density > 1.3 g / cm³) and light plastics (density < 1.15 g / cm³) by density sorting. The density sorting adopts the buoyancy density sorting method and uses calcium chloride solution as the density medium.

[0079] (2) Heavy plastic was mixed with an amine cracking agent (triethylenediamine) and a catalyst (sodium acetate), with 5 parts heavy plastic, 15 parts triethylenediamine, and 0.25 parts sodium acetate. The mixture was stirred and heated at 105°C for 6 hours to obtain a heavy plastic-derived additive.

[0080] (3) Mix virgin asphalt (No. 70 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt at a mass ratio of 60:80, heat to 230℃, and stir at 300 r / min until the heated asphalt mixture is molten and fully mixed. Then, add 15 parts by mass of petroleum-based asphalt recycling agent (model RA101), continue stirring for 25 minutes, and adjust the viscosity of the blend to 2.0 Pa·s. Cool the recycled asphalt compound to 160℃, add 5% by weight of heavy plastic derivative additive, adjust the stirring speed to 600 r / min, and stir for 15 minutes to obtain heavy plastic derivative additive modified recycled asphalt.

[0081] (4) Lightweight plastics were mixed with the catalyst Fe / γ-Al2O3, with the catalyst amount being 5% by weight of the lightweight plastics. Catalytic pyrolysis was carried out in a fixed-bed pyrolysis reactor at a reaction temperature of 600℃ for 2 hours under a nitrogen atmosphere (flow rate of 100 mL / min). The reaction products were condensed and separated to obtain carbon nanotubes (yield of 30% by weight) and hydrogen-rich gas (yield of 15% by weight).

[0082] Comparative Example 2

[0083] A method for recycling plastic waste without using photocatalytic oxidation includes the following steps:

[0084] (1) The recycled plastic waste is rinsed with clean water, dried at 75℃ for 5 hours, and crushed to a size of 25-35 mm². Then, the plastic is separated into high dielectric constant plastics and low dielectric constant plastics by electrostatic sorting technology. The electrostatic sorting device adopts a high-precision electrostatic separator with a working voltage of 35 kV, a drum speed of 80 r / min, and a sorting efficiency of 90%.

[0085] (2) High dielectric constant plastic was directly mixed with virgin asphalt (No. 60 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt at a mass ratio of 5:50:80. The mixture was heated to 230℃ and stirred at a speed of 320 r / min until the heated asphalt mixture was molten and fully mixed. Then, 15 parts by mass of petroleum-based asphalt rejuvenator (Sinopec Shanghai Petrochemical Co., Ltd., model RA101) was added, and stirring was continued for 30 minutes. The viscosity of the blend was adjusted to 2.1 Pa·s to obtain the plastic / asphalt composite material.

[0086] (3) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe2O4 / ZSM-5, at a catalyst dosage of 10% by weight of the low-dielectric-constant plastic. The MnFe2O4 loading in the MnFe2O4 / ZSM-5 catalyst was 25%, and the silicon-to-aluminum ratio of ZSM-5 was 30. Catalytic conversion was carried out in a microwave device with a power of 1000W and a frequency of 2.45GHz. The reaction temperature was controlled at 620℃, the reaction time was 20 minutes, and the reaction atmosphere was argon (flow rate 80 mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield 45% by weight), light hydrocarbon oils (yield 30% by weight), and olefin-containing gaseous products (yield 13% by weight).

[0087] Comparative Example 3

[0088] A method for recycling plastic waste without using microwave catalytic conversion includes the following steps:

[0089] (1) The recycled plastic waste is rinsed with clean water, dried at 80℃ for 6 hours, and crushed to a size of 30-40 mm². Then, it is separated into high dielectric constant plastics and low dielectric constant plastics by electrostatic separation technology. The electrostatic separation device adopts a high-efficiency electrostatic separator (model HH-ES400), with a working voltage of 40kV, a drum speed of 90r / min, and a separation efficiency of 92%.

[0090] (2) A high-dielectric-constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the Ti-MOF amounting to 3% by weight of the high-dielectric-constant plastic. The Ti-MOF photocatalyst had a specific surface area of ​​1500 m² / g and an average particle size of 150 nm. Under an oxygen atmosphere (oxygen flow rate of 90 mL / min), the mixture was irradiated with 395 nm wavelength ultraviolet light (light intensity of 150 mW / cm²), the reaction temperature was controlled at 80 °C, and the reaction time was 4 hours to obtain a surface-oxidized high-dielectric-constant plastic. The surface-oxidized high-dielectric-constant plastic had an oxygen-containing group content of 12% by weight.

[0091] (3) New asphalt (No. 50 road petroleum asphalt, Sinopec Shanghai Petrochemical Co., Ltd.) and recycled asphalt were mixed at a mass ratio of 60:100, heated to 230℃, and stirred at a speed of 320 r / min until the heated asphalt mixture was molten and fully mixed. Then, a bio-based asphalt recycler (main components: 50% rosin, 40% turpentine, and 10% natural resin acid derivatives) was added at a mass ratio of 13 parts, and stirring was continued for 28 minutes. The viscosity of the blend was adjusted to 2.1 Pa·s. The recycled asphalt compound was cooled to 170℃, and a surface-oxidized high dielectric constant plastic was added at a mass ratio of 6% by weight. The stirring speed was adjusted to 630 r / min, and stirring was carried out for 16 minutes to obtain a photo-oxidized modified plastic / asphalt composite material.

[0092] (4) A low-dielectric-constant plastic was mixed with a catalyst, Fe / γ-Al₂O₃, at a catalyst dosage of 10% by weight of the low-dielectric-constant plastic. Catalytic pyrolysis was carried out in a fixed-bed pyrolysis reactor at a reaction temperature of 650°C for 2.5 hours under a nitrogen atmosphere (flow rate of 100 mL / min). The reaction products were condensed and separated to obtain carbon nanotubes (yield of 35% by weight) and hydrogen-rich gas (yield of 20% by weight).

[0093] Comparative Example 4

[0094] A method for recycling plastic waste without functionalizing it with carbon nanostructures includes the following steps:

[0095] (1) The recycled plastic waste is rinsed with clean water, dried at 85℃ for 7 hours, and crushed to a size of 35-45 mm². Then, the plastic is separated into high dielectric constant plastic and low dielectric constant plastic by electrostatic separation technology. The electrostatic separation device adopts a high-performance electrostatic separator with a working voltage of 45 kV, a drum speed of 100 r / min, and a separation efficiency of 94%.

[0096] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the Ti-MOF amounting to 4% by weight of the high dielectric constant plastic. The Ti-MOF photocatalyst had a specific surface area of ​​1650 m² / g and an average particle size of 120 nm. Under an oxygen atmosphere (oxygen flow rate of 100 mL / min), the mixture was irradiated with 405 nm wavelength ultraviolet light (light intensity of 180 mW / cm²), the reaction temperature was controlled at 85 °C, and the reaction time was 5 hours to obtain a surface-oxidized high dielectric constant plastic. The oxygen-containing group content on the surface of the surface-oxidized high dielectric constant plastic was 13.5% by weight.

[0097] (3) New asphalt (No. 40 road petroleum asphalt) and recycled asphalt were mixed at a mass ratio of 70:110, heated to 235°C, and stirred at 330 r / min until the heated asphalt mixture was molten and fully mixed. Then, 14 parts by mass of bio-based asphalt recycler (main components are 45% rosin, 45% turpentine, and 10% natural resin acid derivatives) were added, and stirring was continued for 30 minutes. The viscosity of the blend was adjusted to 2.2 Pa·s. The recycled asphalt compound was cooled to 175°C, and 7% by weight of surface-oxidized high dielectric constant plastic was added. The stirring speed was adjusted to 640 r / min, and stirring was carried out for 18 minutes to obtain the photo-oxidized plastic / asphalt composite material.

[0098] (4) A low-dielectric-constant plastic was mixed with a microwave-absorbing catalyst, MnFe₂O₄ / ZSM-5, at a catalyst dosage of 12% by weight of the low-dielectric-constant plastic. The MnFe₂O₄ loading in the MnFe₂O₄ / ZSM-5 catalyst was 30%, and the silicon-to-aluminum ratio of ZSM-5 was 25. Catalytic conversion was carried out in a microwave apparatus with a power of 1100 W and a frequency of 2.45 GHz. The reaction temperature was controlled at 630 °C, the reaction time was 25 minutes, and the reaction atmosphere was argon (flow rate 90 mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield 55% by weight), light hydrocarbon oils (yield 32% by weight), and olefin-containing gaseous products (yield 14% by weight).

[0099] Example and Comparative Performance Tests and Comparisons

[0100] To verify the technical effectiveness of the method of the present invention, performance tests were conducted on the modified asphalt materials and carbon nanostructures prepared in Examples 1-5 and Comparative Examples 1-4. The test items included the high-temperature performance, anti-aging performance, and storage stability of the modified asphalt, as well as the morphological characteristics, specific surface area, electrochemical performance, and adsorption performance of the carbon nanostructures.

[0101] 1. Performance testing of modified asphalt

[0102] (1) High temperature performance test: The softening point and 135℃ Brookfield rotation viscosity of modified asphalt were determined in accordance with the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0103] (2) Anti-aging performance test: The anti-aging performance of modified asphalt was evaluated by using the thin film oven aging test (TFOT) and pressure aging vessel test (PAV) in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0104] (3) Storage stability test: The storage stability of modified asphalt was evaluated by aluminum tube test method in accordance with the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0105] The test results are shown in Table 1:

[0106] Table 1. Performance test results of modified asphalt

[0107] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Softening point / °C 52.5 53.8 55.2 56.7 58.1 50.6 48.2 53 55.4 Brookfield rotational viscosity at 135℃ (Pa·s) 0.85 0.92 1.05 1.18 1.3 0.75 0.65 0.95 1.1 TFOT quality change rate / % 0.15 0.13 0.11 0.09 0.08 0.32 0.45 0.18 0.15 PAV softening point increment / °C 4.5 4.2 3.8 3.5 3.2 7.8 9.5 5.2 4.8 Storage stability (48h softening point difference) / ℃ 1.8 1.5 1.2 0.9 0.7 4.5 8.2 2.5 1.5

[0108] As shown in Table 1, the photo-oxidative modified plastic / asphalt composite materials prepared in Examples 1-5 of this invention exhibit excellent high-temperature performance, anti-aging properties, and storage stability. Compared with Comparative Example 1 (conventional thermocatalytic method), the softening point of Example 3 increased by 4.6℃, the TFOT mass change rate decreased by 65.6%, the softening point increment after PAV decreased by 51.3%, and the storage stability improved by 73.3%, indicating that the method of this invention can significantly improve the comprehensive performance of modified asphalt. Compared with Comparative Example 2 (without photocatalytic oxidation), the softening point of Example 3 increased by 7.0℃, and the storage stability improved by 85.4%, demonstrating that photocatalytic oxidation treatment plays an important role in improving the compatibility and interfacial bonding strength between plastics and asphalt.

[0109] 2. Performance testing of carbon nanostructures

[0110] (1) Specific surface area test: The specific surface area (BET method) and pore structure characteristics of carbon nanostructures were determined by nitrogen adsorption-desorption method.

[0111] (2) Electrochemical performance testing: Cyclic voltammetry (CV) and constant current charge-discharge testing were conducted using a three-electrode system (working electrode: carbon nanostructure, counter electrode: platinum sheet, reference electrode: saturated calomel electrode) to evaluate the electrochemical performance of the carbon nanostructure.

[0112] (3) Adsorption performance test: The adsorption performance of carbon nanostructures for organic pollutants was evaluated by the methylene blue adsorption method.

[0113] The test results are shown in Table 2:

[0114] Table 2 Performance test results of carbon nanostructures

[0115] Test Project Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Specific surface area (m² / g) 800 950 1050 1100 1200 450 680 520 750 Pore ​​volume (cm³ / g) 0.85 1.05 1.25 1.45 1.65 0.35 0.6 0.45 0.8 Capacitance value (F / g) 185 220 260 310 350 95 150 120 180 Methylene blue adsorption capacity (mg / g) 250 320 380 450 520 120 180 150 210

[0116] As shown in Table 2, the functionalized carbon nanostructures prepared in Examples 1-5 of this invention possess excellent specific surface area, pore structure, electrochemical performance, and adsorption performance. Compared with Comparative Example 1 (conventional thermocatalytic method), the specific surface area of ​​Example 3 increased by 133.3%, the capacitance value increased by 173.7%, and the methylene blue adsorption capacity increased by 216.7%, indicating that the method of this invention can significantly improve the performance of carbon nanostructures. Compared with Comparative Example 3 (without microwave catalytic conversion), the specific surface area of ​​Example 3 increased by 101.9%, and the capacitance value increased by 116.7%, indicating that microwave catalytic conversion technology plays an important role in improving the yield and quality of carbon nanostructures. Compared with Comparative Example 4 (without carbon nanostructure functionalization treatment), the capacitance value of Example 3 increased by 44.4%, and the methylene blue adsorption capacity increased by 81.0%, indicating that nitrogen and phosphorus co-doping plays an important role in improving the functionality of carbon nanostructures.

[0117] The test results above show that the photo-oxidative modified plastic / asphalt composite material and functionalized carbon nanostructures prepared by the method of the present invention have excellent comprehensive properties and have significant technical effects compared with traditional methods.

[0118] Based on the above embodiments and test results, the preferred embodiment of the present invention is Embodiment 3, which specifically includes:

[0119] (1) The recycled plastic waste is rinsed with clean water, dried at 80℃ for 6 hours, and crushed to a size of 25-35 mm². Then, it is separated into high dielectric constant plastics and low dielectric constant plastics by electrostatic separation technology. The electrostatic separation device operates at a voltage of 35 kV, the drum speed is 80 r / min, and the separation efficiency reaches 90%.

[0120] (2) A high dielectric constant plastic was mixed with a titanium metal-organic framework (Ti-MOF) photocatalyst, with the Ti-MOF amounting to 3% by weight of the high dielectric constant plastic. Under an oxygen atmosphere (oxygen flow rate of 90 mL / min), the mixture was irradiated with 395 nm wavelength ultraviolet light (light intensity of 150 mW / cm²), the reaction temperature was controlled at 80 °C, and the reaction time was 4 hours to obtain a surface-oxidized high dielectric constant plastic. The surface-oxidized high dielectric constant plastic had an oxygen-containing group content of 12% by weight.

[0121] (3) Mix new asphalt and recycled asphalt at a mass ratio of 60:100, heat to 230℃, and stir at a speed of 320 r / min. Then, add 13 parts by mass of bio-based asphalt recycler, continue stirring for 28 minutes, and adjust the viscosity of the blend to 2.1 Pa·s. Cool the recycled asphalt compound to 170℃, add 6% by weight of surface-oxidized high dielectric constant plastic, adjust the stirring speed to 630 r / min, and stir for 16 minutes to obtain photo-oxidized modified plastic / asphalt composite material.

[0122] (4) A low dielectric constant plastic was mixed with a microwave-absorbing catalyst MnFe2O4 / ZSM-5, with the catalyst amount being 10% by weight of the low dielectric constant plastic. Catalytic conversion was carried out in a microwave apparatus with a power of 1000W and a frequency of 2.45GHz. The reaction temperature was controlled at 620℃, the reaction time was 20 minutes, and the reaction atmosphere was argon (flow rate 80 mL / min). The reaction products were separated by condensation to obtain carbon nanostructures (yield 50% by weight), light hydrocarbon oils (yield 30% by weight), and olefin-containing gaseous products (yield 13% by weight).

[0123] (5) The carbon nanostructure was mixed with a nitrogen source (urea) and a phosphorus source (phosphoric acid) at a mass ratio of 10:3:1 and heat-treated at 460℃ for 1.6 hours. A nitrogen- and phosphorus co-doped functionalized carbon nanostructure was obtained, with a nitrogen content of 7% by weight, a phosphorus content of 2.5% by weight, and a specific surface area of ​​1050 m² / g.

[0124] This optimal implementation scheme enables the refined sorting and high-value utilization of all components of plastic waste. The prepared photo-oxidative modified plastic / asphalt composite materials and functionalized carbon nanostructures have excellent comprehensive performance and significant economic and environmental benefits.

[0125] This invention achieves refined sorting and high-value utilization of all components of plastic waste through an innovative combination of electrostatic sorting technology, photocatalytic oxidation technology, and microwave catalysis technology. It solves the problems of low sorting efficiency, high energy consumption, and poor environmental friendliness in existing technologies and has important application prospects.

[0126] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recycling plastic waste, characterized in that, Includes the following steps: After being washed, dried, and crushed, the recycled plastic waste is separated into high dielectric constant plastics and low dielectric constant plastics using electrostatic sorting technology. The high dielectric constant plastic was mixed with a titanium metal-organic framework photocatalyst and photocatalytically oxidized in an oxygen atmosphere to obtain a surface-oxidized high dielectric constant plastic. New asphalt and recycled asphalt are mixed in a certain mass ratio, a bio-based asphalt regenerator is added, and then the surface-oxidized high dielectric constant plastic is added to obtain a photo-oxidized modified plastic / asphalt composite material. The low dielectric constant plastic is mixed with a microwave absorption catalyst and catalytically converted in a microwave device to obtain carbon nanostructures, light hydrocarbon oils and olefin-containing gaseous products; the microwave absorption catalyst is manganese ferrite / ZSM-5 molecular sieve, and its amount is 5-15% by weight of the low dielectric constant plastic. The carbon nanostructures were mixed with nitrogen and phosphorus sources and subjected to heat treatment to obtain nitrogen and phosphorus co-doped functionalized carbon nanostructures. The high dielectric constant plastic has a dielectric constant greater than 3.5 and includes polyethylene terephthalate, polycarbonate, and polyvinyl chloride; the low dielectric constant plastic has a dielectric constant less than 2.5 and includes polyethylene, polypropylene, and polystyrene; the amount of the titanium metal-organic framework photocatalyst is 1-5% by weight of the high dielectric constant plastic; the photocatalytic oxidation is carried out under ultraviolet light irradiation at a wavelength of 365-405 nm, with a light intensity of 50-200 mW / cm², a reaction temperature of 60-90℃, and a reaction time of 2-6 hours; the carbon nanostructure includes a composite material of carbon nanotubes and graphene quantum dots.

2. The method for recycling plastic waste according to claim 1, characterized in that, The oxygen-containing group content of the surface of the high dielectric constant plastic modified by surface oxidation is 8-15% by weight.

3. The method for recycling plastic waste according to claim 1, characterized in that, The mass ratio of the new asphalt to the recycled asphalt is 40-60:60-120; the amount of the bio-based asphalt regenerator is 10-15 parts by mass; the main components of the bio-based asphalt regenerator are a mixture of rosin, turpentine oil, and natural resin acid derivatives.

4. The method for recycling plastic waste according to claim 1, characterized in that, When the new asphalt and the recycled asphalt are mixed, the heating temperature is 210-240℃; after adding the bio-based asphalt regenerator, the mixture is stirred and the viscosity is adjusted to 1.8-2.3 Pa·s; when the temperature is lowered to 150-180℃, the surface-oxidized high dielectric constant plastic is added, with an amount of 3-8% by weight; the mixture is stirred at high speed for 10-20 minutes to obtain the photo-oxidized plastic / asphalt composite material.

5. A method for recycling plastic waste according to claim 1, characterized in that, The microwave device has a power of 600-1200 watts and a frequency of 2.45 GHz; the reaction temperature of the catalytic conversion is 550-650℃, the reaction time is 10-30 minutes; the reaction atmosphere is nitrogen or argon, and the flow rate is 50-100 ml / min.

6. A method for recycling plastic waste according to claim 1, characterized in that, The yield of the carbon nanostructures reaches 40-60% by weight of the low dielectric constant plastic; the yield of the light hydrocarbon oils reaches 25-35% by weight of the low dielectric constant plastic; and the yield of the olefin-containing gaseous products reaches 10-15% by weight of the low dielectric constant plastic.

7. A method for recycling plastic waste according to claim 1, characterized in that, The nitrogen source is urea or ammonia, and the phosphorus source is phosphoric acid or hypophosphoric acid; the mass ratio of the carbon nanostructure to the nitrogen source and the phosphorus source is 10:3:1; the heat treatment temperature is 400-500℃, and the heat treatment time is 1-2 hours; the nitrogen content in the nitrogen and phosphorus co-doped functionalized carbon nanostructure is 5-8% by weight, the phosphorus content is 1-3% by weight, and the specific surface area reaches 800-1200 square meters / gram.