A regenerated plastic based on high-activity rice hull ash and a preparation method and application thereof

Abstract

This invention relates to the field of recycled plastics technology, specifically to a recycled plastic based on highly active rice husk ash, its preparation method, and its application. The recycled plastic is obtained by extrusion of 60-80 parts by weight of recycled plastic granules, 20-40 parts by weight of highly active rice husk ash, 3-5 parts by weight of interfacial compatibilizer, 2-4 parts by weight of lubricant, and 0.5-1 parts by weight of heat stabilizer. The recycled plastic granules are selected from one or more of high-density polyethylene and polypropylene. The highly active rice husk ash is prepared by calcining and acid-hydrolyzing rice husks. The highly active rice husk ash exhibits strong interfacial bonding with the recycled plastic granules. The recycled plastic obtained by this invention has a density of only 0.95 g / cm³. 3 ~1.02g / cm 3 With a tensile strength exceeding 19MPa and an aging resistance tensile strength ratio exceeding 90%, it combines lightweight, high strength, and aging resistance, making it suitable for various engineering scenarios.

Description

Technical Field

[0001] This invention relates to the field of recycled plastics technology, specifically to a recycled plastic based on highly active rice husk ash, its preparation method, and its application. Background Technology

[0002] Petroleum-based virgin plastic resins rely on fossil resources for production, resulting in high carbon emissions during the process. They are also difficult to degrade naturally after use, and large-scale waste disposal easily causes white pollution, leading to low resource utilization rates. Current conventional waste plastic recycling technologies process waste plastics into recycled granules through crushing, washing, sorting, and melt granulation. Recycled plastics generally suffer from reduced mechanical properties, poor structural stability, and insufficient aging resistance, limiting their application to low-end products and failing to meet the strength, toughness, and durability requirements of high-performance engineering materials.

[0003] Agricultural waste rice husk ash is widely available and abundant, but it has low surface activity and poor compatibility with plastic matrices. Without activation treatment, it is difficult to form an effective interface with recycled plastics. Direct compounding not only fails to improve material performance but also easily leads to a decline in mechanical properties, making it difficult to achieve high-value utilization of waste plastics and rice husk ash. The industry urgently needs high-performance, green, and low-carbon recycling composite technology. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a recycled plastic based on highly active rice husk ash, its preparation method, and its application.

[0005] To facilitate understanding of this invention, the materials used in this invention and their abbreviations are listed below: High-density polyethylene, abbreviated as HDPE. Polypropylene, abbreviated as PP.

[0006] The first objective of this invention is to provide a recycled plastic based on highly active rice husk ash, which is obtained by mixing and extruding 60 to 80 parts of recycled plastic granules, 20 to 40 parts of highly active rice husk ash, 3 to 5 parts of interface compatibilizer, 2 to 4 parts of lubricant, and 0.5 to 1 part of heat stabilizer by weight.

[0007] The recycled plastic granules are selected from one or more of high-density polyethylene and polypropylene.

[0008] The interface compatibilizer is selected from any one of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted ethylene-vinyl acetate copolymer.

[0009] The lubricant is selected from any one of polyethylene wax, oxidized polyethylene wax, and stearic acid.

[0010] The heat stabilizer is selected from any one of antioxidant 1010, antioxidant 168, and antioxidant B225.

[0011] Highly active rice husk ash is prepared from rice husks through calcination and acid hydrolysis activation. The content of highly active amorphous SiO2 in the highly active rice husk ash is ≥90%, and the silanol content is 1.0 mmol / g~1.5 mmol / g. Therefore, highly active rice husk ash exhibits strong interfacial bonding with recycled plastic particles. Highly active rice husk ash can significantly improve the strength and aging resistance of substrates.

[0012] Preferably, the recycled plastic granules comprise 70 parts, the highly active rice husk ash comprises 30 parts, the interface compatibilizer comprises 4 parts, the lubricant comprises 3 parts, and the heat stabilizer comprises 0.75 parts.

[0013] Preferably, the method for preparing the highly active rice husk ash includes the following steps: The rice husks are cleaned and dried, then calcined at 500℃~600℃ for 2h~3h, and cooled to obtain primary active rice husk ash.

[0014] Primary activated rice husk ash was mixed with a 5%–10% sulfuric acid solution at a solid-liquid ratio of 1g:5mL–8mL and soaked at 40℃–50℃ and 200rpm–400rpm for 1–2 hours. The rice husk ash was repeatedly rinsed with deionized water until the pH of the filtrate reached 6.5–7.0. The rinsed rice husk ash was then dried at 105℃–110℃ for 3–5 hours to obtain highly activated rice husk ash. The sulfuric acid solution effectively etched the surface of the rice husk ash, removing impurities and generating active sites, thus increasing the specific surface area. Under the given solid-liquid ratio, temperature, and time conditions, ensuring sufficient activation of the primary activated rice husk ash, washing to neutrality and drying stabilized the moisture content, significantly improving the interfacial bonding ability between the rice husk ash and recycled plastics.

[0015] Preferably, the calcination temperature is 550°C and the time is 2.5 hours.

[0016] Preferably, the sulfuric acid solution has a mass fraction of 7%.

[0017] Preferably, the solid-liquid ratio is 1g:7.5mL.

[0018] The second objective of this invention is to provide a method for preparing recycled plastics based on highly active rice husk ash, comprising the following steps: Waste plastics are washed, dried, and crushed into particles with a diameter of 2mm to 5mm. These particles are then extruded and granulated at 150℃ to 180℃ to obtain recycled plastic granules. These recycled plastic granules are cylindrical particles with a diameter of 2mm to 5mm.

[0019] Mix 60-80 parts recycled plastic granules, 20-40 parts highly active rice husk ash, 3-5 parts interface compatibilizer, 2-4 parts lubricant, and 0.5-1 part heat stabilizer at 80-100℃ and 300-500rpm for 15-20 minutes to obtain a mixture. The mixing temperature of 80-100℃ allows for full plasticization and dispersion of the plastic and additives, while the extrusion temperature ensures uniform and stable melt. The combination of these two factors allows the highly active rice husk ash to effectively bind, improving the mechanical properties and aging resistance of the substrate and preventing degradation or poor molding.

[0020] The mixture is extruded at 160℃~190℃ to obtain recycled plastic.

[0021] The extrusion equipment used in this invention is a twin-screw extruder, which is a conventional basic equipment in the field of plastics processing. The twin-screw extruder has strong shearing and uniform mixing capabilities, which can ensure that the recycled plastic melt and the highly active rice husk ash are fully integrated, avoid uneven material dispersion, and ensure that the mechanical properties and aging resistance of the finished product are stable and meet the standards, making it suitable for large-scale production needs.

[0022] Preferably, the stirring temperature is 90°C, the stirring speed is 400 rpm, and the stirring time is 17 min.

[0023] The third objective of this invention is to provide an application of highly active rice husk ash-based recycled plastics in the preparation of recycled boards.

[0024] Preferably, the method of the application includes the following steps: passing recycled plastic through an extrusion molding process, cooling and shaping, and cutting to obtain a sheet.

[0025] Preferably, the recycled board is any one of the following: drainage board, green roof drainage protection board, garden sponge city permeable module, roadbed drainage filter board, basement anti-seepage drainage sheet, and municipal greening drainage layer.

[0026] Compared with the prior art, the present invention has the following beneficial effects: 1. The recycled plastic based on highly active rice husk ash of the present invention is obtained by extrusion of 60-80 parts by weight of recycled plastic granules, 20-40 parts by weight of highly active rice husk ash, 3-5 parts by weight of interface compatibilizer, 2-4 parts by weight of lubricant, and 0.5-1 parts by weight of heat stabilizer. The recycled plastic granules are selected from one or more of high-density polyethylene and polypropylene. The interface compatibilizer is selected from any one of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted ethylene-vinyl acetate copolymer. The lubricant is selected from any one of polyethylene wax, oxidized polyethylene wax, and stearic acid. The heat stabilizer is selected from any one of antioxidant 1010, antioxidant 168, and antioxidant B225. The highly active rice husk ash is prepared by calcining and acid-hydrolyzing rice husks. The highly active rice husk ash contains ≥90% highly active amorphous SiO2 and has a silanol content of 1.0 mmol / g-1.5 mmol / g. The active sites, such as silanol groups, on the surface of highly reactive rice husk ash can form chemical bonds with interfacial compatibilizers, achieving excellent interfacial bonding with the recycled plastic matrix. The rice husk ash, uniformly dispersed in the plastic matrix, enhances the material's strength and toughness by bearing stress and inhibiting crack propagation. Simultaneously, it forms a stable network structure, reducing molecular chain slippage and significantly improving the mechanical properties and aging resistance of recycled plastics, thus achieving solid waste reinforcement and toughening. Lubricants improve the mixing and dispersion of raw materials and optimize melt blending and extrusion flowability; heat stabilizers inhibit high-temperature processing degradation, ensuring the material's basic properties and enhancing long-term aging resistance.

[0027] The recycled plastic particles of this invention serve as a continuous matrix, possessing both light weight and toughness, thus establishing a low-density foundation for the substrate. Highly active rice husk ash has a low density; after calcination and acid hydrolysis activation, its surface is rich in active sites and has a low density, allowing it to be uniformly dispersed within the plastic matrix. It bears loads, inhibits crack propagation, and achieves a reinforcing effect. An interfacial compatibilizer promotes the interfacial bonding between the recycled plastic particles and the highly active rice husk ash, preventing agglomeration and ensuring the reinforcing effect is achieved. Lubricants and heat stabilizers ensure smooth processing and prevent material degradation. The recycled plastic of this invention achieves a balance between low density and high mechanical strength through the synergistic effect of recycled plastic particles, highly active rice husk ash, interfacial compatibilizer, lubricant, and heat stabilizer.

[0028] 2. The method for preparing recycled plastic of the present invention involves washing, drying, and crushing waste plastic into particles with a diameter of 2mm to 5mm. The particles are then extruded and granulated at 150℃ to 180℃ to obtain recycled plastic granules. 60 to 80 parts of the recycled plastic granules, 20 to 40 parts of highly active rice husk ash, 3 to 5 parts of an interfacial compatibilizer, 2 to 4 parts of a lubricant, and 0.5 to 1 part of a heat stabilizer are stirred at 80℃ to 100℃ and 300 rpm to 500 rpm for 15 to 20 minutes to obtain a mixture. The mixture is then extruded at 160℃ to 190℃ to obtain recycled plastic. The method of preparing recycled plastic of the present invention, by stirring at 80℃ to 100℃, pre-plasticizes the recycled plastic, and the appropriate stirring speed ensures uniform dispersion of the components, preventing the rice husk ash from agglomerating. Granulation at 150℃~180℃ and extrusion at 160℃~190℃ ensures sufficient melting and flow of the plastic without inducing degradation, while simultaneously promoting the interfacial bonding between rice husk ash and the matrix, ultimately yielding recycled plastics with stable mechanical properties, lightweight, and high strength. The method for preparing recycled plastics in this invention involves forming recycled granules of uniform particle size from waste plastics, then co-extruding them with highly active rice husk ash and additives to achieve efficient solid waste compounding. The process is simple and suitable for industrial production.

[0029] 3. The substrate prepared by this invention has multiple advantages such as lightweight, high strength, aging resistance, and environmental protection. It can be used not only in conventional roadbed and basement drainage scenarios, but also in complex corrosive environments such as saline soil and mine restoration, as well as in lightweight engineering scenarios such as roof greening. It effectively expands the high-end application fields of recycled waste plastic composite materials and promotes the upgrading of civil engineering materials towards green and low-carbon directions. Detailed Implementation

[0030] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the following detailed description, in conjunction with preferred embodiments, provides a clear and complete account of the technical solutions of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0031] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0032] The main materials used in this invention are high-density polyethylene, polypropylene, polyethylene wax, maleic anhydride-grafted polyethylene, oxidized polyethylene wax, stearic acid, antioxidant 1010, antioxidant 168, and antioxidant B225.

[0033] HDPE, PE, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, maleic anhydride grafted ethylene vinyl acetate copolymer, polyethylene wax, oxidized polyethylene wax, stearic acid, antioxidant 1010, antioxidant 168, antioxidant B225.

[0034] Among them, both HDPE and PE were purchased from Dongguan Yari Plastic Products Co., Ltd. Maleic anhydride grafted polyethylene was purchased from Guangzhou Fuyao New Materials Co., Ltd., with the model number ADMER NF528. Maleic anhydride grafted polypropylene was purchased from Dongguan Kaiwan New Materials Co., Ltd., with the model number Mitsui QB510 from Japan. Maleic anhydride grafted ethylene vinyl acetate copolymer was purchased from Nanjing Sute New Materials Co., Ltd., with the model number EVA-g-MAH 1810. Polyethylene wax, with a molecular weight of 3500 and a degree of polymerization of 78, was purchased from Dongguan Suwei New Materials Co., Ltd., with the model number product 100. Oxidized polyethylene wax, with a molecular weight of 4800 and a degree of polymerization of 94, was purchased from Dongguan Shanyi Plastic Co., Ltd., with the model number domestic E-20. Stearic acid was purchased from Kangqiao New Materials Co., Ltd., with the model number domestic 1801. Antioxidant 1010 was purchased from Shanghai Jinghong Chemical Technology Co., Ltd., with the model number antioxidant 1010. Antioxidant 168 was purchased from Dongguan Suwei New Materials Co., Ltd., with the model number antioxidant 168. Antioxidant B225 was purchased from Shanghai Jinghong Chemical Technology Co., Ltd., with the model number antioxidant B225.

[0035] Example 1 A preparation method of recycled plastic based on highly active rice husk ash, comprising the following steps: Wash the waste HDPE plastic, dry it, crush it into particles with a particle size of 3 mm, and extrude and pelletize it at 160 °C to obtain HDPE plastic particles.

[0036] Clean and dry the rice husk, crush it to a particle size of 2 mm, calcine it at 550 °C for 2.5 h, and cool it to obtain primary active rice husk ash.

[0037] Mix the primary active rice husk ash with a sulfuric acid solution with a mass fraction of 7.5% according to a solid-liquid ratio of 1 g: 6.4 mL, stir and soak it at 45 °C at a rotation speed of 200 rpm for 1.5 h. Rinse the rice husk ash repeatedly with deionized water until the pH value of the filtrate is 6.7, and dry the rinsed rice husk ash at 107 °C for 3 h to obtain highly active rice husk ash.

[0038] Mix 70 parts of HDPE plastic particles, 30 parts of highly active rice husk ash, 4 parts of maleic anhydride grafted polyethylene, 3 parts of polyethylene wax, and 0.75 parts of antioxidant 1010 at 90 °C and stir at 400 rpm for 17 min to obtain a mixed material. Feed the mixed material into a twin-screw extruder and extrude it at 170 °C, with a screw speed of 40 rpm, to obtain recycled plastic.

[0039] Example 2 A method for preparing recycled plastics based on highly active rice husk ash includes the following steps: Waste PP plastic is washed, dried, crushed into particles with a diameter of 2mm, and then extruded and granulated at 150℃ to obtain PP plastic granules.

[0040] Rice husks are cleaned, dried, crushed to a particle size of 1 mm, calcined at 500℃ for 2 hours, and then cooled to obtain primary active rice husk ash.

[0041] Primary activated rice husk ash was mixed with a 5% sulfuric acid solution at a solid-liquid ratio of 1g:5mL and soaked at 300rpm for 1 hour at 40℃. The rice husk ash was repeatedly rinsed with deionized water until the pH of the filtrate was 6.5. The rinsed rice husk ash was then dried at 105℃ for 4 hours to obtain highly activated rice husk ash.

[0042] 70 parts of PP plastic granules, 30 parts of highly active rice husk ash, 4 parts of maleic anhydride-grafted polyethylene, 3 parts of polyethylene wax, and 0.75 parts of antioxidant 1010 were stirred at 80°C and 300 rpm for 15 minutes to obtain a mixture. The mixture was then fed into a twin-screw extruder and extruded at 160°C and a screw speed of 30 rpm to obtain recycled plastic.

[0043] Example 3 A method for preparing recycled plastics based on highly active rice husk ash includes the following steps: Waste HDPE plastic is washed, dried, crushed into particles with a diameter of 5mm, and extruded and granulated at 180℃ to obtain HDPE plastic granules.

[0044] Rice husks are cleaned, dried, crushed to a particle size of 3 mm, calcined at 600℃ for 3 hours, and then cooled to obtain primary active rice husk ash.

[0045] Primary activated rice husk ash was mixed with a 10% sulfuric acid solution at a solid-liquid ratio of 1g:8mL and soaked at 50℃ and 400rpm for 2h. The rice husk ash was repeatedly rinsed with deionized water until the pH of the filtrate was 7.0. The rinsed rice husk ash was then dried at 110℃ for 5h to obtain highly activated rice husk ash.

[0046] 70 parts HDPE plastic granules, 30 parts high-activity rice husk ash, 4 parts maleic anhydride grafted polyethylene, 3 parts polyethylene wax, and 0.75 parts antioxidant 1010 were stirred at 100℃ and 500rpm for 20 minutes to obtain a mixture. The mixture was then fed into a twin-screw extruder and extruded at 190℃ with a screw speed of 50rpm to obtain recycled plastic.

[0047] Example 4 A method for preparing recycled plastics based on highly active rice husk ash includes the following steps: The ingredients in Example 1, which consisted of 70 parts HDPE plastic granules, 30 parts high-activity rice husk ash, 4 parts maleic anhydride-grafted polyethylene, 3 parts polyethylene wax, and 0.75 parts antioxidant 1010, were adjusted to 80 parts HDPE plastic granules, 40 parts high-activity rice husk ash, 5 parts maleic anhydride-grafted polyethylene, 4 parts polyethylene wax, and 1 part antioxidant 1010. All other conditions remained the same as in Example 1, resulting in recycled plastic.

[0048] Comparative Example 1 A method for preparing recycled plastics based on highly active rice husk ash includes the following steps: Waste HDPE plastic is washed, dried, crushed into particles with a diameter of 3mm, and extruded and granulated at 160℃ to obtain HDPE plastic granules.

[0049] Rice husks are cleaned and dried, then calcined at 550℃ for 2.5 hours and cooled to obtain highly active rice husk ash.

[0050] 70 parts HDPE plastic granules, 30 parts high-activity rice husk ash, 4 parts maleic anhydride grafted polyethylene, 3 parts polyethylene wax, and 0.75 parts antioxidant 1010 were stirred at 90℃ and 400rpm for 17 minutes to obtain a mixture. The mixture was fed into a twin-screw extruder and extruded at 170℃ with a screw speed of 40rpm to obtain recycled plastic.

[0051] To illustrate the beneficial effects of the present invention, the density, tensile strength, compressive strength and aging resistance of the recycled plastics prepared in Examples 1 to 4 and Comparative Example 1 were tested, and the specific methods are as follows.

[0052] The recycled plastics prepared in Examples 1-4 and Comparative Example 1 were shaped and cut into dumbbell-shaped sheet specimens of type 1A as specified in GB / T 1040.2-2022. The specific dimensions were: total length 174±2 mm, parallel section width 10±0.2 mm, parallel section length 80±1 mm, gauge length 75 mm, and thickness 4 mm. Their tensile strength was then tested, and their aging resistance was tested in a xenon lamp aging test chamber. The index was the ratio of tensile strength before and after the aging test. The tensile strength ratio was the ratio of the tensile strength of the recycled plastic after aging in the xenon lamp aging test chamber to the tensile strength of the unaged recycled plastic.

[0053] The recycled plastics prepared in Examples 1-4 and Comparative Example 1 were cooled and shaped with cold water, then cut into cubic specimens as specified in GB / T1033.1-2008, with standard dimensions of 20mm × 20mm × 20mm, and their density was tested. Subsequently, the compressive strength of the recycled plastics was tested using a universal testing machine.

[0054] The test results of density, tensile strength, compressive strength, and aging resistance of the recycled plastics prepared in Examples 1-4 and Comparative Example 1 are shown in Table 1. The results show that the recycled plastics prepared by this invention have significant performance advantages. Except for the unactivated rice husk ash in Comparative Example 1, the density of the recycled plastics of this invention is between 0.95 g / cm³. 3 ~1.02g / cm 3 It is far lower than the 2.3g / cm³ of traditional concrete drainage boards. 3 ~2.5g / cm 3 Compared to conventional drainage boards with a density of 1.1 g / cm³ 3 ~1.2g / cm 3 This achieves lightweight design, making it easier to handle during on-site construction.

[0055] In terms of strength indicators, the tensile strength of the drainage board substrates of the high-activity rice husk ash group in Examples 1 to 4 is all greater than 19 MPa, and the compressive strength is all greater than 8.5 MPa. Among them, the tensile strength and compressive strength of the recycled plastic prepared in Example 4 reach 22.3 MPa and 10.2 MPa, respectively. Compared with the strength indicators of the recycled plastic of unactivated rice husk ash in Comparative Example 1, the strength indicators are improved by 42% and 50%, respectively, showing the good compatibility and reinforcing effect of high-activity rice husk ash with waste plastic.

[0056] In terms of aging resistance, the tensile strength ratio of the high-activity rice husk ash drainage board substrate is greater than 90%, with Example 4 reaching 93.1%, while the tensile strength ratio of the unactivated rice husk ash group of recycled plastic is only 78.2%, indicating that the high-activity rice husk ash can effectively improve the aging resistance of recycled plastic.

[0057] Table 1. Performance test results of recycled plastics from waste plastics and highly reactive rice husk ash In summary, the recycled plastics made from waste plastics and highly active rice husk ash prepared by this invention combine lightweight, high strength, and excellent aging resistance, realizing the resource utilization of waste plastics and agricultural waste while meeting the requirements for use in drainage board projects, and thus possessing significant application value.

[0058] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described in this invention to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the inventive concept of this invention, can make other changes and modifications to these embodiments, and all such changes and modifications fall within the scope of this invention.

[0059] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. If such modifications and variations fall within the scope of equivalents of this invention, then this invention is also intended to include such modifications and variations.

Claims

1. A recycled plastic based on highly active rice husk ash, characterized in that, It is obtained by mixing and extruding 60-80 parts of recycled plastic granules, 20-40 parts of highly active rice husk ash, 3-5 parts of interface compatibilizer, 2-4 parts of lubricant, and 0.5-1 parts of heat stabilizer, by weight. The recycled plastic granules are selected from one or more of high-density polyethylene and polypropylene; The interface compatibilizer is selected from any one of maleic anhydride-grafted polyethylene, maleic anhydride-grafted polypropylene, and maleic anhydride-grafted ethylene-vinyl acetate copolymer. The lubricant is selected from any one of polyethylene wax, oxidized polyethylene wax, and stearic acid; The heat stabilizer is selected from any one of antioxidant 1010, antioxidant 168, and antioxidant B225; The highly active rice husk ash is prepared by calcining and acid hydrolysis of rice husks.

2. The recycled plastic based on highly active rice husk ash according to claim 1, characterized in that, The composition of the recycled plastic granules is 70 parts, the high-activity rice husk ash is 30 parts, the interface compatibilizer is 4 parts, the lubricant is 3 parts, and the heat stabilizer is 0.75 parts.

3. The recycled plastic based on highly active rice husk ash according to claim 1, characterized in that, The method for preparing the highly active rice husk ash includes the following steps: Clean and dry the rice husks, calcine them at 500℃~600℃ for 2h~3h, and then cool them to obtain primary active rice husk ash. Primary active rice husk ash is mixed with a 5%~10% sulfuric acid solution at a solid-liquid ratio of 1g:5mL~8mL and soaked at 40℃~50℃ and 200rpm~400rpm for 1h~2h. The rice husk ash is repeatedly rinsed with deionized water until the pH of the filtrate is 6.5~7.

0. The rinsed rice husk ash is then dried at 105℃~110℃ for 3h~5h to obtain highly active rice husk ash.

4. The recycled plastic based on highly active rice husk ash according to claim 3, characterized in that, The calcination temperature was 550℃ and the time was 2.5h.

5. The recycled plastic based on highly active rice husk ash according to claim 3, characterized in that, The sulfuric acid solution has a mass fraction of 7%.

6. The recycled plastic based on highly active rice husk ash according to claim 3, characterized in that, The solid-liquid ratio is 1g:7.5mL.

7. The method for preparing recycled plastic based on highly active rice husk ash according to claim 1, characterized in that, Includes the following steps: Waste plastics are washed, dried, and crushed into particles with a diameter of 2mm to 5mm. They are then extruded and granulated at 150℃ to 180℃ to obtain recycled plastic granules. Mix 60-80 parts of recycled plastic granules, 20-40 parts of highly active rice husk ash, 3-5 parts of interface compatibilizer, 2-4 parts of lubricant, and 0.5-1 part of heat stabilizer at 80-100℃ and 300-500rpm for 15-20 minutes to obtain a mixture. The mixture is extruded at 160℃~190℃ to obtain recycled plastic.

8. The method for preparing recycled plastic based on highly active rice husk ash according to claim 7, characterized in that, The stirring temperature was 90℃, the rotation speed was 400 rpm, and the stirring time was 17 min.

9. The application of the highly active rice husk ash-based recycled plastic in the preparation of recycled boards according to claim 1.

10. The application of a recycled plastic based on highly active rice husk ash according to claim 9 in the preparation of drainage boards, characterized in that, The method of the application includes the following steps: extruding recycled plastic, cooling and shaping it, and cutting it to obtain recycled sheets.

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