Preparation method for modifying asphalt by catalyzing waste plastic through biological enzyme

Abstract

The invention relates to a preparation method for modifying asphalt by catalyzing waste plastics through biological enzyme, and aims to realize recycling of the waste plastics and improve the performance of the asphalt through an innovative technical means. The method adopts a composite bio-enzyme catalysis and nano-enhancement technology, and comprises the steps of waste plastic pretreatment, compound enzyme solution preparation, enzyme catalysis modification reaction, interface optimization, post-treatment and the like. Firstly, waste plastic is subjected to low-temperature crushing and surface activation treatment, and an active functional group is introduced to improve the binding force with asphalt; then, a composite solution of laccase, lignin peroxidase and esterase is adopted to catalyze the reaction of the waste plastic and the asphalt, and the mechanical property of the composite material is optimized by adding carbon nanofibers and nano titanium dioxide. Finally, the modified asphalt with excellent performance is obtained through high-speed shearing and anti-aging treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of asphalt modification, and specifically to a preparation method for modifying asphalt with waste plastics by using bio-enzyme catalysis. Background Art

[0002] With the increasingly serious global environmental problems, the treatment and resource utilization of waste plastics have become the focus of attention in today's society. According to statistical data, the global annual production of plastic waste exceeds 300 million tons, and a large amount of waste plastics directly enter landfills or the natural environment due to the lack of effective recycling and treatment, causing huge environmental pollution. Traditional waste plastic treatment methods, such as incineration and landfill, although can temporarily solve the problem of the whereabouts of waste plastics, but bring secondary pollution and resource waste. Therefore, developing an efficient and environmentally friendly waste plastic treatment technology has important practical significance.

[0003] In this context, taking waste plastics as a resource, recycling and reusing them, especially as a modified material applied in road construction, has become a research hotspot in recent years. Asphalt, as the most commonly used road construction material, is widely used in the construction of roads, bridges and airport runways due to its good adhesion, wear resistance, water resistance and high service performance. However, some properties of asphalt, such as high-temperature softening, low-temperature brittleness and crack resistance, still have certain limitations, which affect its use effect under extreme climate conditions. Therefore, modifying asphalt to improve its properties has become an important research direction in the field of materials science.

[0004] In recent years, the research on using waste plastics as asphalt modifiers has gradually received attention. Using waste plastics to modify asphalt can not only effectively reduce the negative impact of plastic waste on the environment, but also improve the properties of asphalt, enhancing its high-temperature stability, low-temperature crack resistance and aging resistance. For example, plastics such as polyethylene (PE), polypropylene (PP), and polystyrene (PS) have been applied to the modification of asphalt, and through physical mixing or chemical reactions with asphalt, the mechanical properties and durability of asphalt have been significantly improved. However, these methods still face problems such as poor adhesion between plastics and asphalt in application, resulting in limited modification effects.

[0005] To overcome this problem, in recent years, some studies have tried to improve the compatibility between plastics and asphalt, and enhance their adhesion and chemical bonding force by introducing different surface treatment methods, such as heat treatment, chemical treatment and surface activation. For example, using methods such as plasma treatment and chemical oxidation to activate the surface of waste plastics can introduce active functional groups such as hydroxyl and carboxyl groups on the plastic surface, thereby increasing the intermolecular interaction force between plastics and asphalt molecules. This surface treatment technology is of great significance for improving the modification effect of asphalt.

[0006] In addition, with the increasing popularity of the concepts of green environmental protection and sustainable development, bio-enzyme catalytic technology, as a mild, efficient, and environmentally friendly catalytic technology, has gradually attracted attention in the research of waste plastic modified asphalt. As a catalyst, bio-enzyme can efficiently catalyze the reaction between waste plastic and asphalt under low-temperature conditions, avoiding the energy consumption and environmental pollution problems in the traditional high-temperature treatment process. Using bio-enzyme to catalyze the modification reaction of waste plastics can promote the formation of surface functional groups on waste plastics, improve the chemical bonding between plastics and asphalt, and enhance the mechanical properties and durability of asphalt.

[0007] In addition, the development of nanotechnology provides new solutions for waste plastic modified asphalt. Nanomaterials, such as nano-titanium dioxide, nano-carbon fiber, etc., due to their unique physical and chemical properties, can significantly improve the mechanical properties, heat resistance, and aging resistance of modified asphalt. The combination of nano-enhancement technology and waste plastic modified asphalt can optimize the interaction between waste plastics and asphalt at the molecular level, thus obtaining more excellent modification effects.

[0008] Therefore, combining bio-enzyme catalytic technology, surface treatment technology, and nano-enhancement technology can not only effectively solve the compatibility problem between waste plastics and asphalt, but also realize the recycling and reuse of waste plastics while improving the performance of modified asphalt, which has important environmental and economic value.

[0009] Through this method of combining multiple technologies, not only can the performance of asphalt be improved and its service life be enhanced, but also it helps to reduce the environmental pollution of waste plastics and promote the realization of sustainable development. The present invention proposes a new preparation method for waste plastic modified asphalt through the combination of bio-enzyme catalysis and nano-enhancement technology, filling the technical gap in this field and having good application prospects. Summary of the Invention

[0010] The purpose of the present invention is to provide a preparation method for waste plastic modified asphalt using bio-enzyme catalysis to solve the problems raised in the above background technology.

[0011] To achieve the above purpose, the present invention provides the following technical solution: A preparation method for waste plastic modified asphalt using bio-enzyme catalysis, through the combination of composite bio-enzyme catalysis and nano-enhancement technology, successively includes the following steps:

[0012] (1) Pretreatment of waste plastics: Wash and dry the waste plastics, then perform low-temperature crushing to obtain waste plastic particles with a particle size of 0.05 - 0.5 mm, and perform surface activation through low-temperature plasma treatment or chemical oxidation to introduce active functional groups such as hydroxyl or carboxyl groups to improve the binding efficiency of subsequent catalytic reactions;

[0013] (2) Preparation of composite bio - enzyme solution: Based on the surface characteristics of the waste plastic particles obtained by pretreatment in step (1), a composite enzyme solution containing laccase, lignin peroxidase and esterase is prepared. Nano - titanium dioxide is added as a catalytic enhancer, a bio - based surfactant and a stabilizer, and the pH value is adjusted to 4.5 - 6.5 to ensure that the enzyme activity adapts to the subsequent reaction conditions;

[0014] (3) Enzyme - catalyzed modification reaction: The waste plastic particles obtained in step (1) and matrix asphalt are mixed evenly at a mass ratio of 8 - 20:100 at 130 - 150 °C to form a preliminary dispersion system. Then, the composite bio - enzyme solution prepared in step (2) is added, and the catalytic reaction is carried out at 60 - 80 °C, so that the surface functional groups of the waste plastic react with asphalt molecules to form chemical bonds and generate a stable composite structure;

[0015] (4) Interface optimization: Nano - carbon fibers are added to the reaction system obtained in step (3), and ultrasonic dispersion is used to enhance the multi - phase interface compatibility among the waste plastic, asphalt and nano - materials, further improving the mechanical properties of the composite structure;

[0016] (5) Post - treatment: The reaction product obtained in step (4) is subjected to high - speed shearing to refine the dispersed phase, an anti - aging agent is added, and it is heat - cured at 120 - 140 °C to obtain modified asphalt with optimized properties.

[0017] As a preferred technical solution of the present invention, in step (1), the waste plastic is selected from one or a mixture of polyethylene, polypropylene, and polystyrene; the cryogenic grinding is carried out using a liquid nitrogen freezing grinding device, the grinding temperature is - 50 °C to - 20 °C, and the average particle size of the waste plastic particles obtained is 0.1 - 0.3 mm.

[0018] As a preferred technical solution of the present invention, in step (1), the specific conditions of the surface activation treatment are as follows:

[0019] Low - temperature plasma treatment: A radio - frequency plasma device is used, with a power of 100 - 200 W, a treatment time of 5 - 10 minutes, and the atmosphere is oxygen or nitrogen to introduce hydroxyl or carboxyl groups on the surface of the waste plastic particles;

[0020] Chemical oxidation treatment: Peracetic acid or hydrogen peroxide solution is used, with a concentration of 5 - 15 wt%, a treatment temperature of 30 - 50 °C, and a treatment time of 10 - 20 minutes.

[0021] As a preferred technical solution of the present invention, in step (2), the preparation of the composite bio - enzyme solution includes the following components and conditions:

[0022] The enzyme activity ratio of laccase, lignin peroxidase and esterase is (1.5 - 2.5):1:1 to match the surface functional group characteristics of the waste plastic particles in step (1);

[0023] The total concentration of the enzyme solution is 1 - 3 U / mL;

[0024] The particle size of the nano-titanium dioxide is 10 - 20 nm, and the addition amount is 5 - 10% of the dry weight of the enzyme to enhance the enzyme catalytic efficiency;

[0025] The bio-based surfactant is sodium lignosulfonate or glycerol fatty acid ester, and the addition amount is 0.2 - 0.5% of the solution mass, preferably 0.3 - 0.4%, to improve the dispersibility of the enzyme solution in step (3);

[0026] The stabilizer is β-cyclodextrin or polyethylene glycol, and the addition amount is 0.1 - 0.3% of the solution mass to maintain the activity of the enzyme at the subsequent reaction temperature.

[0027] As a preferred technical solution of the present invention, in the step (3), the specific conditions of the enzyme-catalyzed modification reaction are:

[0028] The mixing device is a planetary stirrer, the stirring speed is 800 - 1200 rpm, the mixing temperature is 135 - 145 °C, and the mixing time is 20 - 40 minutes to ensure the preliminary dispersion of the waste plastic particles in the matrix asphalt;

[0029] The addition amount of the composite enzyme solution is 0.2 - 0.6% of the mass of the waste plastic particles, and it is added through a constant flow pump at a dropping speed of 0.1 - 0.5 mL / min;

[0030] The catalytic reaction is carried out in a constant-temperature stirring reaction kettle, the reaction temperature is 65 - 75 °C, the stirring speed is 300 - 600 rpm, and the reaction time is 2 - 5 hours to promote chemical bonding.

[0031] As a preferred technical solution of the present invention, the matrix asphalt is petroleum asphalt with a penetration of 60 - 100, a softening point of 45 - 55 °C, and an aromatic content of 20 - 35 wt% to provide reaction sites for chemical bonding with the waste plastic particles in step (3).

[0032] As a preferred technical solution of the present invention, in the step (4), the specifications and dispersion conditions of the nano-carbon fiber are:

[0033] The diameter of the nano-carbon fiber is 10 - 50 nm, and the length is 1 - 10 μm;

[0034] The addition amount of the nano-carbon fiber is 0.5 - 1.5% of the mass of the matrix asphalt, preferably 0.8 - 1.2%, to enhance the mechanical properties of the composite structure generated in step (3);

[0035] The nano-carbon fiber is ultrasonically dispersed using an ultrasonic generator with a frequency of 20 - 25 kHz, a power of 150 - 250 W, and a dispersion time of 5 - 10 minutes.

[0036] As a preferred technical solution of the present invention, in the step (5), the specific conditions of the post-treatment are as follows:

[0037] For high-speed shearing, a high-shear emulsifier is used, with a shearing rate of 3000 - 5000 rpm, a shearing temperature of 140 - 150 °C, and a shearing time of 30 - 60 minutes to refine the dispersed phase formed in step (4);

[0038] The anti-aging agent is a hindered phenol antioxidant or an amine antioxidant, and the addition amount is 0.1 - 0.3% of the mass of the matrix asphalt, preferably 0.15 - 0.25%, to improve the aging resistance of the modified asphalt;

[0039] The ripening is carried out in a heat-insulating stirring kettle at a temperature of 120 - 130 °C, a stirring speed of 200 - 400 rpm, and a time of 20 - 40 minutes.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] Firstly, by combining and modifying waste plastics with asphalt, the present invention not only effectively reduces the environmental pollution caused by waste plastics but also realizes the resource utilization of waste plastics, with significant environmental benefits. The recycling and reuse of waste plastics not only reduce the secondary pollution caused by landfilling and incinerating waste plastics but also greatly reduce the potential harm of plastic waste to soil and water sources. Through the combination of bio-enzyme catalysis, surface activation treatment, and nano-enhancement technology, the bonding force between waste plastics and asphalt is effectively enhanced, improving the performance of asphalt, making it have better thermal stability, low-temperature crack resistance, and aging resistance, thereby increasing the service life of asphalt and the durability of roads.

[0042] Secondly, the technical solution of the present invention can provide an efficient, mild, and environmentally friendly solution for asphalt modification. The use of bio-enzyme catalysis technology not only avoids energy consumption and environmental pollution during high-temperature treatment but also can efficiently promote the chemical reaction between waste plastics and asphalt at a lower temperature, improving the modification effect. The introduction of nano-enhancement technology further optimizes the mechanical properties of the modified asphalt, making it excellent in aspects such as compression resistance, crack resistance, and heat resistance, and suitable for road construction under various climate conditions. This multi-technology collaborative modification method not only improves the overall performance of the modified asphalt but also opens up a new path for the resource utilization of waste plastics, playing a positive role in promoting sustainable development. Detailed implementation manners

[0043] To further illustrate a preparation method of using bio - enzymes to catalyze the modification of waste plastics in asphalt, the following describes specific implementation methods in detail. These examples are only used to illustrate the technical solutions of the present invention and do not limit the protection scope. Equivalent substitutions or improvements made by those skilled in the art without departing from the technical solutions of the present invention all fall within the protection scope of the present invention.

[0044] The present invention provides a preparation method of using bio - enzymes to catalyze the modification of waste plastics in asphalt, which combines nano - enhancement technology and bio - enzyme catalytic reaction to significantly improve the dispersion and mechanical properties of waste plastics in asphalt. The following are the specific implementation steps of this method, including two examples and a comparison data table with a control group.

[0045] Implementation steps: Pretreatment of waste plastics: Wash and dry the waste plastics, and then perform low - temperature crushing to obtain waste plastic particles with a particle size of 0.1 - 0.3 mm.

[0046] Adopt low - temperature plasma treatment or chemical oxidation treatment to introduce active functional groups such as hydroxyl or carboxyl groups on the surface of waste plastic particles.

[0047] Low - temperature plasma treatment: Use a radio - frequency plasma device with a power of 100 - 200 W, a treatment time of 5 - 10 minutes, and an atmosphere of oxygen or nitrogen.

[0048] Chemical oxidation treatment: Use peracetic acid or hydrogen peroxide solution with a concentration of 5 - 15 wt%, a treatment temperature of 30 - 50 °C, and a treatment time of 10 - 20 minutes.

[0049] Prepare a composite bio - enzyme solution: Prepare a composite solution of laccase, lignin peroxidase, and esterase, and the enzyme activity ratio is (1.5 - 2.5):1:1.

[0050] The particle size of nano - titanium dioxide is 10 - 20 nm, and the addition amount is 5 - 10% of the dry weight of the enzyme.

[0051] Add bio - based surfactants such as sodium lignosulfonate or glycerol fatty acid ester (the addition amount is 0.2 - 0.5%), and use β - cyclodextrin or polyethylene glycol as stabilizers (the addition amount is 0.1 - 0.3%).

[0052] The total concentration of the enzyme solution is 1 - 3 U / mL, and the pH is adjusted to 4.5 - 6.5 to ensure that the enzyme activity adapts to the reaction conditions.

[0053] Enzyme - catalyzed modification reaction: Mix the waste plastic particles and matrix asphalt at a mass ratio of 8 - 20:100, control the temperature at 130 - 150 °C, uniformly mix through a planetary mixer, the stirring speed is 800 - 1200 rpm, and the mixing time is 20 - 40 minutes.

[0054] The addition amount of the composite bio-enzyme solution is 0.2 - 0.6% of the mass of the waste plastic particles, and the dropping rate is 0.1 - 0.5 mL / min.

[0055] The reaction temperature is controlled at 65 - 75 °C, the stirring speed is 300 - 600 rpm, and the reaction time is 2 - 5 hours.

[0056] Interface optimization: Add nano-carbon fiber with a specification of a diameter of 10 - 50 nm and a length of 1 - 10 μm, and the addition amount is 0.5 - 1.5% of the mass of the matrix asphalt.

[0057] Use ultrasonic dispersion technology with a frequency of 20 - 25 kHz, a power of 150 - 250 W, and a dispersion time of 5 - 10 minutes.

[0058] Post-treatment: High-speed shearing is carried out using a high-shear emulsifier with a shearing rate of 3000 - 5000 rpm, a shearing temperature of 140 - 150 °C, and a shearing time of 30 - 60 minutes.

[0059] Add anti-aging agents (such as hindered phenol antioxidants or amine antioxidants), and the addition amount is 0.1 - 0.3%.

[0060] Curing is carried out in a heat-insulating stirring kettle with the temperature controlled at 120 - 130 °C, the stirring speed of 200 - 400 rpm, and the time of 20 - 40 minutes.

[0061] Example 1 (bio-enzyme catalytic modified asphalt);

[0062] Pretreatment of waste plastics: Raw material selection: Select polyethylene (PE) waste plastics as raw materials.

[0063] Cleaning and drying: Clean and dry the waste plastics, wash them with deionized water, and dry for 24 hours.

[0064] Low-temperature grinding: Use a liquid nitrogen freezing and grinding device to grind the waste plastics to a particle size of 0.2 mm.

[0065] Surface activation treatment: Use a radio frequency plasma device with a power of 150 W and a treatment time of 8 minutes to introduce active functional groups such as hydroxyl or carboxyl groups.

[0066] Prepare a composite bio-enzyme solution: Prepare a composite solution of laccase, lignin peroxidase, and esterase, with an enzyme activity ratio of 2:1:1 and a total solution concentration of 2 U / mL.

[0067] Add nano-titanium dioxide (particle size of 10 - 20 nm), and the addition amount is 6% of the dry weight of the enzyme to enhance the enzyme catalytic efficiency.

[0068] Add sodium lignosulfonate (surfactant) and β-cyclodextrin (stabilizer), and adjust the pH value to 4.5.

[0069] Enzymatic catalytic modification reaction: Mixing waste plastics and asphalt: Mix waste plastic particles and matrix asphalt at a mass ratio of 10:100, control the mixing temperature at 135 °C, and the mixing time is 30 minutes.

[0070] Adding composite bio-enzyme solution: Drop the composite bio-enzyme solution (the addition amount is 0.5% of the mass of waste plastic particles) into the mixture through a constant flow pump, and the dropping speed is 0.2 mL / min.

[0071] Catalytic reaction conditions: Control the reaction temperature at 70 °C, the stirring speed is 400 rpm, and the reaction time is 3 hours.

[0072] Interface optimization: Adding nano-carbon fiber: Add nano-carbon fiber (diameter 15 nm, length 5 μm) to the reaction system, and the addition amount is 1.0% of the mass of matrix asphalt.

[0073] Ultrasonic dispersion: Use an ultrasonic generator (frequency 22 kHz, power 200 W) to disperse nano-carbon fiber, and the dispersion time is 8 minutes.

[0074] Post-treatment: High-speed shearing: Perform shearing in a high-shear emulsifier, the shearing rate is 4000 rpm, the shearing temperature is 145 °C, and the shearing time is 45 minutes.

[0075] Adding anti-aging agent: Add a hindered phenol antioxidant, and the addition amount is 0.2%.

[0076] Aging treatment: Age in a heat-insulating stirring kettle, control the temperature at 125 °C, the stirring speed is 300 rpm, and the time is 30 minutes.

[0077] Example 2 (different waste plastics and enzymatic catalytic conditions);

[0078] Pretreatment of waste plastics: Raw material selection: Select a mixture of waste polypropylene (PP) and polystyrene (PS).

[0079] Cleaning and drying: The same as in Example 1, use deionized water to clean and dry for 48 hours.

[0080] Low-temperature pulverization: Pulverize the waste plastics to a particle size of 0.3 mm, and use a liquid nitrogen freezing pulverization device for pulverization treatment.

[0081] Chemical oxidation treatment: Use hydrogen peroxide solution (concentration 10 wt%) for chemical oxidation treatment, the treatment temperature is 45 °C, and the treatment time is 15 minutes.

[0082] Prepare a composite bio-enzyme solution: Prepare a composite enzyme solution of laccase, lignin peroxidase and esterase, the enzyme activity ratio is 1.5:1:1, and the enzyme solution concentration is 1.8 U / mL.

[0083] The addition amount of nano-titanium dioxide is 7% of the dry weight of the enzyme.

[0084] Add fatty acid glyceride (surfactant) with an addition amount of 0.3%, and polyethylene glycol (stabilizer) with an addition amount of 0.2%.

[0085] Enzyme-catalyzed modification reaction: Mix waste plastic particles and matrix asphalt at a mass ratio of 12:100, control the mixing temperature at 145°C, and the mixing time is 40 minutes.

[0086] Dropwise addition of composite bio-enzyme solution: The addition amount of the composite bio-enzyme solution is 0.4% of the mass of the waste plastic particles, and the dropping rate is 0.3 mL / min.

[0087] The reaction temperature is 72°C, the stirring speed is 450 rpm, and the reaction time is 4 hours.

[0088] Interface optimization: Add nano-carbon fiber (diameter 20 nm, length 8 μm) with an addition amount of 1.2%.

[0089] Post-treatment: High-speed shearing, the shearing rate is 4500 rpm, the shearing temperature is 150°C, and the shearing time is 50 minutes.

[0090] Add hindered phenol antioxidant with an addition amount of 0.25%.

[0091] Control group (asphalt without modification treatment);

[0092] Waste plastic treatment: Raw material selection: The control group uses untreated waste plastics, and directly tests with waste plastics without cryogenic crushing or surface activation.

[0093] Waste plastic crushing: The waste plastics are not cryogenically crushed or mechanically treated, and are directly used for mixing with asphalt.

[0094] Surface treatment: Without any surface activation treatment, the waste plastics are directly used without plasma treatment or chemical oxidation.

[0095] Asphalt selection: Use standard petroleum asphalt with a penetration of 70, a softening point of 50°C, and an aromatic content of 25 wt%, without any modification treatment.

[0096] Modification process: Mixing of waste plastics and asphalt: Mix untreated waste plastics and petroleum asphalt at a mass ratio of 10:100, control the temperature at 140°C, and the mixing time is 30 minutes.

[0097] No bio-enzyme solution is used: Do not add any composite bio-enzyme solution, and directly mix waste plastics and asphalt.

[0098] Post-treatment: Shearing: Directly perform shearing in a high-shear emulsifier at a shearing rate of 3500 rpm, a shearing time of 30 minutes, and a temperature set at 145°C for a conventional shearing operation.

[0099] Anti-aging and mechanical property tests: Conduct standard tests on aging resistance and mechanical properties, and analyze the softening point, penetration, crack resistance, and tensile bond strength of this control group.

[0100] Comparison results: Through the above experimental steps, the performance differences among Example 1, Example 2, and the control group can be compared. The following are the comparison data of mechanical properties:

[0101]

[0102]

[0103] Through the experimental steps and performance comparisons of the above examples and the control group, it can be seen that the method of bio-enzyme catalytic modification of asphalt significantly improves the mechanical properties, aging resistance, and crack resistance of asphalt. Especially under the combined action of surface treatment of waste plastics, enzyme-catalyzed reactions, and nano-enhancement technology, the performance of the modified asphalt has been significantly improved. These experimental steps and data provide a scientific basis for the practical application of this method and demonstrate its potential in environmental protection and resource utilization.

[0104] The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements on some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method for modifying asphalt with waste plastics by using bio - enzyme catalysis, characterized in that, Through the combined catalytic action of composite bio-enzymes and nano-enhancement technology, the following steps are included in sequence: (1) Pretreatment of waste plastics: The waste plastics are cleaned, dried and then subjected to cryogenic grinding to obtain waste plastic particles with a particle size of 0.05 - 0.5 mm. The surface is activated by cryogenic plasma treatment or chemical oxidation to introduce active functional groups such as hydroxyl or carboxyl groups, so as to improve the bonding efficiency of subsequent catalytic reactions. (2) Preparation of composite bio-enzyme solution: Based on the surface characteristics of the waste plastic particles obtained from the pretreatment in step (1), a composite enzyme solution containing laccase, lignin peroxidase and esterase is prepared. Nano-titanium dioxide is added as a catalytic enhancer, a bio-based surfactant and a stabilizer, and the pH value is adjusted to 4.5 - 6.5 to ensure that the enzyme activity adapts to the subsequent reaction conditions. (3) Enzyme-catalyzed modification reaction: The waste plastic particles obtained in step (1) and matrix asphalt are mixed evenly at a mass ratio of 8 - 20:100 at 130 - 150 °C to form a preliminary dispersion system. Then, the composite bio-enzyme solution prepared in step (2) is added, and the catalytic reaction is carried out at 60 - 80 °C, so that the surface functional groups of the waste plastics and the asphalt molecules undergo chemical bonding to generate a stable composite structure. (4) Interface optimization: Nano-carbon fibers are added to the reaction system obtained in step (3), and ultrasonic dispersion is used to enhance the multiphase interface compatibility among the waste plastics, asphalt and nano-materials, further improving the mechanical properties of the composite structure. (5) Post-treatment: The reaction product obtained in step (4) is subjected to high-speed shearing to refine the dispersed phase, an anti-aging agent is added, and it is kept warm and cured at 120 - 140 °C to obtain modified asphalt with optimized properties.

2. The preparation method of a modified asphalt using bio - enzyme - catalyzed waste plastics according to claim 1, characterized in that, In step (1), the waste plastics are selected from one or a mixture of polyethylene, polypropylene, and polystyrene; the cryogenic grinding uses a liquid nitrogen freezing grinding device, and the grinding temperature is -50 °C to -20 °C, and the average particle size of the waste plastic particles obtained is 0.1 - 0.3 mm.

3. The preparation method of a modified asphalt using bio-enzyme to catalyze waste plastics according to claim 1, characterized in that, In the said step (1), the specific conditions of the surface activation treatment are as follows: Cryogenic plasma treatment: Use a radio frequency plasma device with a power of 100 - 200 W, a treatment time of 5 - 10 minutes, and the atmosphere is oxygen or nitrogen to introduce hydroxyl or carboxyl groups on the surface of the waste plastic particles. Chemical oxidation treatment: Use peracetic acid or hydrogen peroxide solution with a concentration of 5 - 15 wt%, a treatment temperature of 30 - 50 °C, and a treatment time of 10 - 20 minutes.

4. The preparation method of using bio - enzyme to catalyze the modification of waste plastic asphalt according to claim 1, characterized in that, In the said step (2), the preparation of the composite bio-enzyme solution includes the following components and conditions: The enzyme activity ratio of laccase, lignin peroxidase and esterase is (1.5 - 2.5):1:1 to match the surface functional group characteristics of the waste plastic particles in step (1). The total concentration of the enzyme solution is 1 - 3 U / mL. The particle size of nano-titanium dioxide is 10 - 20 nm, and the addition amount is 5 - 10% of the dry weight of the enzyme to enhance the enzyme catalytic efficiency. The bio-based surfactant is sodium lignosulfonate or glycerol fatty acid ester, and the addition amount is 0.2 - 0.5% of the solution mass to improve the dispersibility of the enzyme solution in step (3). The stabilizer is β-cyclodextrin or polyethylene glycol, and the addition amount is 0.1-0.3% of the solution mass to maintain the activity of the enzyme at the subsequent reaction temperature.

5. The preparation method of a modified asphalt using bio-enzyme catalysis for waste plastics according to claim 1, characterized in that, In the step (3), the specific conditions of the enzyme-catalyzed modification reaction are as follows: The mixing device is a planetary stirrer, with a stirring speed of 800-1200 rpm, a mixing temperature of 135-145 °C, and a mixing time of 20-40 minutes to ensure the preliminary dispersion of the waste plastic particles in the matrix asphalt; The addition amount of the composite bio-enzyme solution is 0.2-0.6% of the mass of the waste plastic particles, and it is added through a constant flow pump at a dropping rate of 0.1-0.5 mL / min; The catalytic reaction is carried out in a constant-temperature stirring reaction kettle, with a reaction temperature of 65-75 °C, a stirring speed of 300-600 rpm, and a reaction time of 2-5 hours to promote chemical bonding.

6. The preparation method of a modified asphalt using bio - enzyme - catalyzed waste plastics according to claim 1, characterized in that, The matrix asphalt is a petroleum asphalt with a penetration of 60-100, a softening point of 45-55 °C, and an aromatic content of 20-35 wt% to provide reaction sites for chemical bonding with the waste plastic particles in step (3).

7. A preparation method for modifying waste plastic modified asphalt by using bio-enzyme catalysis according to claim 1, characterized in that, In the step (4), the specifications and dispersion conditions of the nanofiber carbon are as follows: The diameter of the nanofiber carbon is 10-50 nm, and the length is 1-10 μm; The addition amount of the nanofiber carbon is 0.5-1.5% of the mass of the matrix asphalt to enhance the mechanical properties of the composite structure formed in step (3); The nanofiber carbon is dispersed by ultrasonic waves. An ultrasonic generator is used for ultrasonic dispersion, with a frequency of 20-25 kHz, a power of 150-250 W, and a dispersion time of 5-10 minutes.

8. The preparation method of using bio - enzyme to catalyze the modification of waste plastic modified asphalt according to claim 1, characterized in that, In the step (5), the specific conditions of the post-treatment are as follows: High-speed shearing is carried out using a high-shear emulsifier, with a shearing rate of 3000-5000 rpm, a shearing temperature of 140-150 °C, and a shearing time of 30-60 minutes to refine the dispersed phase formed in step (4); The anti-aging agent is a hindered phenol antioxidant or an amine antioxidant, and the addition amount is 0.1-0.3% of the mass of the matrix asphalt to improve the anti-aging performance of the modified asphalt; The ripening is carried out in a heat-insulating stirring kettle, with a temperature of 120-130 °C, a stirring speed of 200-400 rpm, and a time of 20-40 minutes.

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