Preparation of solid waste-based magnetic multi-level porous material and method for removing micro / nanoplastics from polluted water

Abstract

The present invention provides a method for preparing a solid waste-based magnetic multi-level porous material and removing micro / nanoplastics from polluted water bodies, belonging to the field of solid waste resource utilization and water treatment. The present invention provides a method for preparing a solid waste-based magnetic multi-level porous material, comprising the following steps: mixing biomass raw materials, bauxite slag, and coal gangue with a strong base and then roasting them under a protective atmosphere to obtain roasted clinker containing biochar and iron; mixing the roasted clinker with water and performing a hydrothermal crystallization reaction to generate a molecular sieve to obtain the solid waste-based magnetic multi-level porous material. The solid waste-based magnetic multi-level porous material contains both the macropores of biochar and the micropores of the molecular sieve, can be used for adsorbing micro / nanoplastics in water bodies, and can be recycled multiple times. The solid waste raw material of the present invention is a large amount of solid waste stored, and the material prepared therefrom can play the role of treating waste with waste, with obvious economic and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the fields of solid waste resource utilization and water treatment, and in particular to a method for preparing a solid waste-based magnetic multi-level porous material and removing micro / nanoplastics from polluted water. Background Art

[0002] Microplastics generally refer to plastic particles with a particle size of less than 5mm, while nanoplastics refer to plastic particles with a particle size of less than 1000nm. Micro / nanoplastics can be divided into primary plastics and secondary plastics according to their source. Primary micro / nanoplastics are mostly tiny plastic particles contained in industrial products, which are directly released into the environment during the production and use process. Secondary micro- and nanoplastics are formed after cracking, abrasion or degradation through physical, chemical and biological effects. Micro / nanoplastics have the characteristics of small particle size, wide distribution and difficulty in degradation, which leads to their strong bioaccumulation and environmental persistence. As the size of plastics decreases, their environmental migration ability and biological toxicity become more obvious, posing a potential threat to the ecosystem.

[0003] Aquatic ecosystems are considered to be prone to accumulating micro- and nanoplastics. Surface runoff is the primary route of micro- and nanoplastics' entry into aquatic ecosystems. Different types of micro- and nanoplastics, such as fragments, fibers, particles, and foam, are often present in aquatic ecosystems. Their morphology and size vary significantly depending on the type of plastic and how it is fragmented. Consequently, the high concentrations of micro- and nanoplastics in water bodies, along with their diverse morphologies and sizes, make their management challenging.

[0004] Methods for removing micro- and nanoplastics can be broadly categorized into five categories: filtration, coagulation, biological methods, adsorption, and advanced oxidation. Filtration and advanced oxidation are limited by the pore size of the plastic, resulting in low efficiency and poor practical application. Adsorption, a more widely studied method, is difficult to apply to actual water bodies because materials like biochar, while effective at adsorption, cannot be recycled or reused. Summary of the Invention

[0005] The present invention provides a method for preparing a solid waste-based magnetic hierarchical porous material and removing micro- and nanoplastics from contaminated water. Using biomass, bauxite slag, and coal gangue as raw materials, and through calcination and crystallization, the solid waste-based magnetic hierarchical porous material is produced, effectively removing micro- and / or nanoplastics from water.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a solid waste-based magnetic multi-level porous material, comprising the following steps:

[0008] The biomass raw materials, bauxite waste slag, coal gangue and strong alkali are mixed and roasted under a protective atmosphere to obtain roasted clinker containing biochar and iron;

[0009] The roasted clinker is mixed with water and subjected to a hydrothermal crystallization reaction to generate a molecular sieve, thereby obtaining the solid waste-based magnetic multi-level porous material.

[0010] Preferably, the bauxite waste slag comprises, by mass fraction, 30-35% Fe2O3, 15-20% SiO2, 25-30% Al2O3, 2-10% CaO, 5-10% Na2O, 2-10% TiO2 and 1.5-2% impurities.

[0011] Preferably, the coal gangue comprises, by mass fraction, 0.5-1% Fe2O3, 55-60% SiO2, 40-45% Al2O3, 0.15-0.2% CaO, 1.02% TiO2 and 0.5-1% impurities.

[0012] Preferably, the molar ratio of the total carbon element to the aluminum element in the biomass raw material, bauxite waste slag, and coal gangue is 0.2-0.4:1;

[0013] The total molar ratio of aluminum element to silicon element is 1:0.8~1.2.

[0014] Preferably, the molar ratio of the total aluminum element in the biomass raw material, bauxite waste slag, and coal gangue to the metal element in the strong base is 1:1.5-5.

[0015] Preferably, the calcination temperature is 400-800° C. and the calcination time is 1-3 hours.

[0016] Preferably, the temperature of the hydrothermal crystallization reaction is 90-150° C., and the time is 3-24 hours.

[0017] The present invention also provides a solid waste-based magnetic multi-level porous material prepared by the preparation method described in the above technical solution.

[0018] The present invention also provides a method for removing micro- and / or nano-plastics from polluted water, comprising the following steps:

[0019] (1) The solid waste-based magnetic multilevel porous material described in the above technical solution is mixed with polluted water to adsorb micro- and / or nanoplastics, and then separated under the action of a magnetic field to obtain a solid waste-based magnetic multilevel porous material adsorbed with micro- and / or nanoplastics.

[0020] Preferably, the method further comprises: (2) mixing the solid waste-based magnetic multilevel porous material adsorbed with micro- and / or nanoplastics with a desorbent to desorb the micro- and / or nanoplastics, thereby obtaining a desorbed solid waste-based magnetic multilevel porous material;

[0021] (3) Repeat steps (1) to (2) on the desorbed solid waste-based magnetic multi-level porous material.

[0022] The solid waste raw materials used in this invention (biomass, bauxite slag, and coal gangue) are large, stockpiled solid wastes with low utilization rates and significant environmental hazards. The materials produced from these materials can effectively treat waste with waste. The magnetic biochar-molecular sieve composite material, which combines the macropores of biochar with the micropores of molecular sieves, can be used as an adsorbent for micro- and nanoplastics of various sizes. Furthermore, the material is magnetic and can be recovered under an applied magnetic field, providing technical support for the removal of micro- and nanoplastics from water.

[0023] After adsorption is completed, the multi-level porous material can be regenerated by sodium chloride solution and recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the XRD pattern of the solid waste-based magnetic multi-level porous material in Example 1;

[0025] Figure 2 This is the SEM image of the solid waste-based magnetic multi-level porous material in Example 1;

[0026] Figure 3 This is the removal effect of the solid waste-based magnetic multi-level porous material on PE plastic balls in water in Example 1;

[0027] Figure 4 This is the removal effect of the solid waste-based magnetic multi-level porous material on PS plastic balls in water after 5 cycles in Example 3. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a solid waste-based magnetic multi-level porous material, comprising the following steps:

[0029] The biomass raw materials, bauxite waste slag, coal gangue and strong alkali are mixed and roasted under a protective atmosphere to obtain roasted clinker containing biochar and iron;

[0030] The roasted clinker is mixed with water and subjected to a hydrothermal crystallization reaction to generate a molecular sieve, thereby obtaining the solid waste-based magnetic multi-level porous material.

[0031] The invention mixes biomass raw materials, bauxite waste slag, coal gangue and strong alkali, and then roasts them under a protective atmosphere to obtain roasted clinker containing biochar and iron.

[0032] In the present invention, the mixing preferably includes: grinding the biomass raw material, bauxite waste slag, and coal gangue separately through a 100-mesh sieve, mixing, drying, and then mixing with a strong base.

[0033] In the present invention, the molar ratio of the total carbon element to the aluminum element in the biomass raw material, bauxite waste slag and coal gangue is preferably 0.2~0.4:1, and the molar ratio of the total aluminum element to the silicon element is 1:1; in a specific embodiment of the present invention, the molar ratio of the total carbon element to the aluminum element in the biomass raw material, bauxite waste slag and coal gangue can be 0.2:1, 0.3:1 or 0.4:1, and the molar ratio of the total aluminum element to the silicon element is preferably 1:0.8~1.2. In a specific embodiment of the present invention, the molar ratio of the total aluminum element to the silicon element can be 1:0.8, 1:0.9, 1:1, 1.1: or 1.2:.

[0034] In the present invention, the biomass raw material preferably includes corn straw.

[0035] In the present invention, the bauxite waste slag preferably comprises Bayer red mud; and the molar ratio of aluminum to silicon in the bauxite waste slag is preferably greater than 1.

[0036] In terms of mass fraction, the bauxite waste slag preferably includes 30-35% of Fe2O3. In a specific embodiment of the present invention, the mass fraction of Fe2O3 in the bauxite waste slag may be 30%, 31%, 32%, 33%, 33.8%, 34% or 35%;

[0037] In terms of mass fraction, the bauxite waste slag preferably includes SiO2 15-20%. In a specific embodiment of the present invention, the mass fraction of SiO2 in the bauxite waste slag can be 15%, 16%, 16.06%, 17%, 18%, 19% or 20%;

[0038] In terms of mass fraction, the bauxite waste slag preferably includes Al2O3 25-30%. In a specific embodiment of the present invention, the mass fraction of Al2O3 in the bauxite waste slag can be 25%, 26%, 26%, 27%, 28%, 29.04% or 30%;

[0039] In terms of mass fraction, the bauxite waste slag preferably includes 2-10% CaO. In a specific embodiment of the present invention, the mass fraction of CaO in the bauxite waste slag may be 2%, 3%, 4%, 5%, 6%, 6.67%, 7%, 8%, 9% or 10%;

[0040] In terms of mass fraction, the bauxite waste slag preferably includes 5-10% Na2O. In a specific embodiment of the present invention, the mass fraction of Na2O in the bauxite waste slag may be 5%, 6%, 6.58%, 7%, 8%, 9% or 10%;

[0041] In terms of mass fraction, the bauxite waste slag preferably includes TiO2 2-10%. In a specific embodiment of the present invention, the mass fraction of TiO2 in the bauxite waste slag can be 2%, 3%, 4%, 5%, 5.86%, 6%, 7%, 8%, 9% or 10%;

[0042] In terms of mass fraction, the bauxite waste slag preferably includes 1.5-2% impurities. In a specific embodiment of the present invention, the mass fraction of the impurities in the bauxite waste slag can be 1.5%, 1.6%, 1.63%, 1.7%, 1.8%, 1.9% or 2%.

[0043] In the present invention, the molar ratio of aluminum to silicon in the coal gangue is preferably less than 1.

[0044] In terms of mass fraction, the coal gangue preferably includes 0.5% to 1% of Fe2O3. In a specific embodiment of the present invention, the mass fraction of Fe2O3 in the coal gangue can be 0.5%, 0.6%, 0.62%, 0.7%, 0.8%, 0.9% or 1%;

[0045] In terms of mass fraction, the coal gangue preferably includes SiO255-60%. In a specific embodiment of the present invention, the mass fraction of SiO2 in the coal gangue can be 55%, 55.48%, 56%, 57%, 58%, 59% or 60%;

[0046] In terms of mass fraction, the coal gangue preferably includes 40-45% Al2O3. In a specific embodiment of the present invention, the mass fraction of Al2O3 in the coal gangue may be 45%, 41%, 41.83%, 42%, 43%, 44% or 45%;

[0047] In terms of mass fraction, the coal gangue preferably includes 0.15-0.2% CaO. In a specific embodiment of the present invention, the mass fraction of CaO in the coal gangue may be 0.15%, 0.16%, 0.17%, 0.18%, 0.19% or 0.2%;

[0048] In terms of mass fraction, the coal gangue preferably includes TiO21.02%;

[0049] In terms of mass fraction, the coal gangue preferably includes 0.5-1% impurities. In a specific embodiment of the present invention, the mass fraction of the impurities in the coal gangue can be 0.5%, 0.6%, 0.7%, 0.8%, 0.87%, 0.9% or 1%.

[0050] In the present invention, the molar ratio of the total aluminum element in the biomass raw materials, bauxite waste slag, and coal gangue to the metal element in the strong base is preferably 1:2~6. In a specific embodiment of the present invention, the molar ratio of the total aluminum element in the biomass raw materials, bauxite waste slag, and coal gangue to the metal element in the strong base can be 1:2, 1:3, 1:4, 1:5 or 1:6; the strong base preferably includes sodium hydroxide.

[0051] In the present invention, the calcination temperature is preferably 400-800°C, and the time is 1-3 hours; in a specific embodiment of the present invention, the calcination temperature can be 400°C, 500°C, 600°C, 700°C or 800°C, and the time can be 1 hour, 2 hours or 3 hours.

[0052] In the present invention, the calcination is preferably carried out in a tubular furnace in a nitrogen atmosphere; the flow rate of the nitrogen is preferably 200 mL / min.

[0053] During the roasting process, the biomass raw materials are carbonized, the bauxite phase is activated, and the iron phase in the bauxite is reduced.

[0054] After obtaining the roasted clinker containing biochar and iron, the present invention mixes the roasted clinker with water and performs a hydrothermal crystallization reaction to generate a molecular sieve, thereby obtaining the solid waste-based magnetic multi-level porous material.

[0055] In the present invention, the mass ratio of the roasted clinker to water is preferably 1:10-15. In a specific embodiment of the present invention, the mass ratio of the roasted clinker to water can be 1:10, 1:11, 1:12, 1:13, 1:14 or 1:15.

[0056] In the present invention, the temperature of the hydrothermal crystallization reaction is preferably 90~150℃, and the time is preferably 3~24h. In a specific embodiment of the present invention, the temperature of the hydrothermal crystallization reaction can be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃ or 150℃, and the time can be 3h, 5h, 8h, 12h, 15h, 18h, 21h or 24h.

[0057] After the hydrothermal crystallization reaction is completed, the present invention preferably filters the obtained product, and then washes and dries the filtered solid.

[0058] The present invention also provides a solid waste-based magnetic multi-level porous material prepared by the preparation method described in the above technical solution

[0059] The present invention also provides a method for removing micro- and / or nano-plastics from polluted water, comprising the following steps:

[0060] (1) The solid waste-based magnetic multilevel porous material described in the above technical solution is mixed with polluted water to adsorb micro- and / or nanoplastics, and then separated under the action of a magnetic field to obtain a solid waste-based magnetic multilevel porous material adsorbed with micro- and / or nanoplastics.

[0061] In the present invention, the concentration of the solid waste-based magnetic multilevel porous material in the mixed solution is preferably 50 mg / L.

[0062] In the present invention, the adsorption time is preferably 1 to 4 hours.

[0063] In the present invention, the intensity of the magnetic field is preferably 20~100 kA / m. In a specific embodiment of the present invention, the intensity of the magnetic field can be 20kA / m, 30kA / m, 40kA / m, 50kA / m, 60kA / m, 70kA / m, 80kA / m, 90kA / m or 100kA / m.

[0064] In the present invention, the method preferably further comprises:

[0065] (2) mixing the solid waste-based magnetic multilevel porous material adsorbed with micro- and / or nanoplastics with a desorbent to desorb the micro- and / or nanoplastics, thereby obtaining the desorbed solid waste-based magnetic multilevel porous material;

[0066] In the present invention, the desorbent is preferably a sodium chloride solution, and the concentration of the sodium chloride solution is preferably 1-3 mol / L.

[0067] In the present invention, the desorption temperature is preferably 15-35° C., and the desorption time is preferably 0.5-3 h.

[0068] (3) Repeat steps (1) to (2) on the desorbed solid waste-based magnetic multi-level porous material.

[0069] The preparation of the solid waste-based magnetic multi-level porous material provided by the present invention and the method for removing micro / nanoplastics from polluted water bodies are described in detail below with reference to the examples, but they should not be understood as limiting the scope of protection of the present invention.

[0070] Example 1

[0071] Biomass feedstock (corn straw), bauxite waste (composition by mass: Fe₂O₃ 33.96%, SiO₂ 16.06%, Al₂O₃ 29.24%, CaO 6.67%, Na₂O 6.58%, TiO₂ 5.86%, and others 1.63%), and coal gangue (composition by mass: Fe₂O₃ 0.62%, SiO₂ 55.48%, Al₂O₃ 41.83%, CaO 0.18%, TiO₂ 1.02%, and others 0.87%) were ground through a 100-mesh sieve and mixed in a ratio of n(C):n(Al):n(Si) = 0.2:1:1. The dried mixed material was mixed with sodium hydroxide (Na:n(Al) = 3) and calcined in a tube furnace under a nitrogen atmosphere at 600°C for 1.6 hours to produce clinker.

[0072] 2 g of the calcined clinker was added to a 50 mL polytetrafluoroethylene liner reactor, 30 mL of water was added, and the mixture was hydroheated at 100°C for 12 h. After solid-liquid separation, the obtained solid was washed and dried to obtain a solid waste-based magnetic multilevel porous material.

[0073] The solid waste-based magnetic multilevel porous material of Example 1 was placed in a fluorescently labeled PE plastic ball solution with a particle size of 50 nm and a concentration of 10 mg / L. The concentration of the solid waste-based magnetic multilevel porous material was 50 mg / L. After an adsorption time of 2 hours, the solid waste-based magnetic multilevel porous material was separated from the solution by a magnet, and the removal rate of PE plastic balls in the solution reached 96.7%.

[0074] Figure 1 This is the XRD pattern of the solid waste-based magnetic multi-level porous material in Example 1;

[0075] Depend on Figure 1 It can be seen that the synthesized material contains type A zeolite and magnetite. Type A zeolite has micropores and has a good adsorption effect on small-sized nanoplastics. Magnetite has superparamagnetism and can be recovered under the condition of an external magnetic field.

[0076] Figure 2 This is the SEM image of the solid waste-based magnetic multi-level porous material in Example 1;

[0077] Depend on Figure 2 It can be seen that a composite material including biochar, zeolite and magnetite was synthesized, and the zeolite phase, magnetic phase and biochar were uniformly dispersed.

[0078] Figure 3 This is the removal effect of the solid waste-based magnetic multi-level porous material in Example 1 on PE plastic balls in water.

[0079] Example 2

[0080] Biomass feedstock (corn straw), bauxite waste (composition by mass: Fe₂O₃ 33.96%, SiO₂ 16.06%, Al₂O₃ 29.24%, CaO 6.67%, Na₂O 6.58%, TiO₂ 5.86%, and others 1.63%), and coal gangue (composition by mass: Fe₂O₃ 0.62%, SiO₂ 55.48%, Al₂O₃ 41.83%, CaO 0.18%, TiO₂ 1.02%, and others 0.87%) were ground through a 100-mesh sieve and mixed in a ratio of n(C):n(Al):n(Si) = 0.3:1:1. The dried mixed material was mixed with sodium hydroxide (Na:n(Al) = 4) and calcined in a tube furnace under a nitrogen atmosphere at 700°C for 2.2 hours to produce clinker.

[0081] 3 g of the roasted clinker was added to a 50 mL polytetrafluoroethylene liner reactor, 30 mL of water was added, and the mixture was hydroheated at 100 °C for 16 h. After solid-liquid separation, the obtained solid was washed and dried to obtain a solid waste-based magnetic multilevel porous material.

[0082] The solid waste-based magnetic multilevel porous material from Example 2 was placed in a solution of fluorescently labeled PVC plastic balls with a particle size of 1 μm and a concentration of 10 mg / L. The concentration of the solid waste-based magnetic multilevel porous material was 50 mg / L, and the adsorption time was 3 hours. The solid waste-based magnetic multilevel porous material was then separated from the solution using a magnet, achieving a 94.8% removal rate of the PVC plastic balls.

[0083] The adsorbed solid waste-based magnetic multilevel porous material was regenerated in a 1.5 mol / L sodium chloride solution at 25°C for 1.5 h, and then added to a 10 mg / L fluorescent-labeled PVC plastic ball solution (the concentration of the solid waste-based magnetic multilevel porous material was 50 mg / L) for adsorption for 3 h, with a removal rate of 91.8%.

[0084] Example 3

[0085] Biomass feedstock (green tea scraps), bauxite waste (composition by mass: Fe₂O₃ 33.96%, SiO₂ 16.06%, Al₂O₃ 29.24%, CaO 6.67%, Na₂O 6.58%, TiO₂ 5.86%, and others 1.63%), and coal gangue (composition by mass: Fe₂O₃ 0.62%, SiO₂ 55.48%, Al₂O₃ 41.83%, CaO 0.18%, TiO₂ 1.02%, and others 0.87%) were ground through a 100-mesh sieve and mixed in a ratio of n(C):n(Al):n(Si) = 0.25:1:1. The dried mixed material was mixed with sodium hydroxide at a ratio of n(Na):n(Al) = 3.3 and calcined in a tube furnace under a nitrogen atmosphere at 650°C for 1.5 hours to produce clinker.

[0086] 2 g of the roasted clinker was added to a 50 mL polytetrafluoroethylene liner reactor, 30 mL of water was added, and the mixture was hydroheated at 95°C for 22 h. After solid-liquid separation, the obtained solid was washed and dried to obtain a solid waste-based magnetic multilevel porous material.

[0087] The solid waste-based magnetic multi-level porous material of Example 3 was placed on a fluorescent label surface with a particle size of 1 μm and a concentration of 10 mg / L and NH 4+ In a solution of PS plastic balls containing the solid waste-based magnetic multilevel porous material, the concentration was 10 mg / L, and the adsorption time was 2 hours. The solid waste-based magnetic multilevel porous material was then separated from the solution using a magnet, achieving a 98.3% removal rate of the PS plastic balls.

[0088] The adsorbed solid waste-based magnetic multilevel porous material was regenerated by 1.3 mol / L sodium chloride solution at 25°C for 1.5 h, and then added to a 10 mg / L fluorescent-labeled PVC plastic ball solution (the concentration of the solid waste-based magnetic multilevel porous material was 10 mg / L) for adsorption for 2 h. The above steps were repeated 5 times, and the removal rates were 93.1%, 91.6%, 91.2%, 90.8% and 90.6%, respectively.

[0089] Figure 4 This is the removal effect of the solid waste-based magnetic multi-level porous material on PS plastic balls in water after 5 cycles in Example 3.

[0090] Comparative Example 1

[0091] RMBC-2 in Example 2 of patent CN 115869909 A.

[0092] Comparison was made with the adsorption experiment of micro / nano plastics conducted by the product in Example 2 of the present invention:

[0093] The two materials were placed in a solution of fluorescently labeled PVC plastic balls with a particle size of 1 μm and a concentration of 10 mg / L. The solid waste-based magnetic multilevel porous material concentration was 50 mg / L, and the adsorption time was 2 hours. The solid waste-based magnetic multilevel porous material was then separated from the solution using a magnet. The removal efficiency of Example 2 was 90.9%, while the removal rate of RMBC-2 was 44%.

[0094] In addition, compared with patent CN 115869909 A, the raw materials of the embodiments of the present invention are all solid waste, no external aluminum silicon source is required, and no suspension liquid is required to synthesize zeolite during the operation, which makes the operation simpler.

[0095] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for removing microplastics from polluted water, characterized in that: The following steps are involved: (1) Mixing the solid waste-based magnetic multi-level porous material with polluted water to adsorb microplastics, and then separating them under the action of a magnetic field to obtain a solid waste-based magnetic multi-level porous material adsorbed with microplastics; The method for preparing the solid waste-based magnetic multi-level porous material comprises the following steps: The biomass raw materials, bauxite waste slag, coal gangue and strong alkali are mixed and roasted under a protective atmosphere to obtain roasted clinker containing biochar and iron; The roasted clinker is mixed with water and subjected to a hydrothermal crystallization reaction to generate a molecular sieve, thereby obtaining the solid waste-based magnetic multi-level porous material; Calculated by mass fraction, the bauxite waste residue includes 30-35% of Fe2O3, 15-20% of SiO2, 25-30% of Al2O3, 2-10% of CaO, 5-10% of Na2O, 2-10% of TiO2 and 1.5-2% of impurities; Calculated by mass fraction, the coal gangue includes Fe2O3 0.5-1%, SiO2 55-60%, Al2O3 40-45%, CaO 0.15-0.2%, TiO2 1.02% and impurities 0.5-1%, and the sum of the mass fractions of Fe2O3, SiO2, Al2O3, CaO, TiO2 and impurities is 100%; The molar ratio of the total carbon element to the aluminum element in the biomass raw material, bauxite waste slag and coal gangue is 0.2-0.4:1, and the molar ratio of the total aluminum element to the silicon element is 1:(0.8-1.2); The calcination temperature is 400-800°C and the calcination time is 1-3 hours; The temperature of the hydrothermal crystallization reaction is 90-150° C., and the time is 3-24 hours.

2. The method according to claim 1, characterized in that The molar ratio of the total aluminum element in the biomass raw material, bauxite waste slag and coal gangue to the metal element in the strong base is 1: (2-6).

3. The method according to claim 1, characterized in that Also includes: (2) mixing the solid waste-based magnetic multilevel porous material adsorbed with microplastics with a desorbent to desorb the microplastics, thereby obtaining a desorbed solid waste-based magnetic multilevel porous material; (3) Repeat steps (1) to (2) on the desorbed solid waste-based magnetic multi-level porous material.

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