Preparation method of modified household garbage incineration fly ash

Abstract

The invention relates to the technical field of environmental waste treatment, and discloses a preparation method of modified household garbage incineration fly ash, the modified household garbage incineration fly ash comprises the following components by mass: 90-99 parts of a fly ash matrix; 0.1 to 2 parts of a plasma activation layer; 0.5 to 8 parts of a silicon oxide coating layer; the preparation method comprises the following steps: pretreating the fly ash; performing plasma activation; preparing a mineralizing solution; performing biomimetic mineralization; and calcining at low temperature. The plasma activation layer is introduced, the silicon oxide coating layer is constructed, and the phosphorus oxide or the boron oxide is cooperatively introduced, so that the microstructure and the surface chemical property of the material are effectively optimized, the specific surface area and the pore volume of the material are increased, and a microporous, mesoporous and macropore synergistic multistage pore channel structure is constructed; the adsorption capacity and the adsorption rate of various waste gas pollutants are improved.

Description

Technical Field

[0001] This application relates to the field of environmental waste treatment technology, specifically a method for preparing modified municipal solid waste incineration fly ash. Background Technology

[0002] Municipal solid waste incineration, as an efficient technology for waste reduction and harmless treatment, is widely used globally. However, the fly ash generated during incineration contains high concentrations of heavy metals, dioxins, and other harmful substances, and is classified as hazardous waste. Its safe disposal and resource utilization have become a serious challenge facing the environmental field. Traditional fly ash disposal methods, such as solidification and landfill, not only occupy a large amount of land resources but also pose long-term environmental risks, failing to fundamentally solve the problem.

[0003] Existing technologies have been extensively explored for the resource utilization of fly ash from municipal solid waste incineration. For example, researchers have attempted to use it as an admixture in cement building materials or in the preparation of roadbed materials, aiming to solidify its harmful components and achieve large-scale utilization. In addition, some studies have focused on using fly ash as a potential adsorbent for treating pollutants in wastewater or exhaust gases.

[0004] However, existing methods for improving the adsorption performance of unmodified municipal solid waste incineration fly ash often involve acid-base activation, high-temperature calcination, or the introduction of a single modifier. However, these methods are complex, energy-intensive, and prone to causing secondary pollution. Existing modification methods are generally unable to effectively construct multi-level porous structures with high specific surface area, abundant active sites, and excellent mass transfer performance, and they also fail to fully address the problem of fly ash surface inertization. Therefore, this invention provides a method for preparing modified municipal solid waste incineration fly ash to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a method for preparing modified municipal solid waste incineration fly ash, which solves the problems of small specific surface area, underdeveloped pore structure, lack of surface active sites, and poor adsorption selectivity in existing municipal solid waste incineration fly ash.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A first aspect of the present invention provides a modified municipal solid waste incineration fly ash, comprising the following components in parts by weight: Fly ash matrix: 90-99 parts; Plasma activation layer: 0.1-2 parts; Silicon oxide coating: 0.5-8 parts; Phosphorus oxides: 0.01-0.5 parts.

[0007] 90-99 parts of fly ash matrix: Municipal solid waste incineration fly ash itself has a complex mineral composition, mainly including silicates, aluminosilicates and a small amount of metal oxides. Although the adsorption performance of raw fly ash is limited due to its dense structure and limited specific surface area, as an industrial solid waste, it provides abundant silicon, aluminum, calcium and other elements for this invention, which are the core material basis for the subsequent modification process.

[0008] Plasma activation layer (0.1-2 parts): Utilizing plasma-assisted low-temperature activation technology, the non-thermal effects of high-energy particles (such as electrons, ions, and active free radicals) in plasma are employed to selectively physical etch and chemically modify the fly ash substrate surface within a relatively low temperature range (150℃ to 250℃). This process not only effectively removes the passivation layer from the fly ash surface, exposing more potential active sites, but also allows plasma to induce the formation of new micropores and mesopores on the fly ash surface in situ, introducing abundant active functional groups (such as hydroxyl, carboxyl, carbonyl, and active carbon dots). These activation sites and functional groups significantly increase the specific surface area and surface energy of the fly ash, and serve as heterogeneous nucleation centers for silica precursors in subsequent biomimetic mineralization processes, effectively lowering the nucleation energy barrier and promoting the uniform and dense growth of the silicon oxide coating layer on its surface.

[0009] 0.5-8 parts of silicon oxide coating: This coating is mainly composed of amorphous silica (SiO2), and its formation benefits from the precise control of biomimetic mineralization technology. This invention draws on the principle of precisely controlling the growth of inorganic minerals under mild conditions in living organisms. By introducing biomolecular template agents (such as gelatin or chitosan) as structure-directing agents, and under precise pH gradient induction, it guides the silicic acid precursor to undergo in-situ self-assembly, polymerization, and cross-linking on the plasma-activated fly ash surface. The three-dimensional network-like silicon oxide layer formed in this process not only effectively stabilizes the mineral structure of the fly ash, but also, during the subsequent low-temperature calcination process, precisely forms a macroporous network with controllable size and good connectivity in the space occupied by the biomolecular template agent after its removal.

[0010] Phosphorus oxide or boron oxide (0.01 to 0.5 parts, based on phosphorus or boron): This component is a further functional modification of the silicon oxide coating layer. During the biomimetic mineralization process, the amount of phosphate or borate added is precisely controlled to co-deposit with the silica precursor on the fly ash surface, thereby forming silicon-phosphorus composite oxides or silicon-boron composite oxides within the silicon oxide framework. These phosphorus or boron elements are covalently bonded to the silicon oxide structure, rather than being simple physical dopants, thus ensuring the stability and persistence of the functional components. The introduction of phosphorus or boron can significantly alter the electronic structure and acidity / basicity of the material surface, increasing the number of Lewis acid sites or Brønsted acid sites. These newly added active sites endow the modified fly ash with a stronger adsorption affinity for specific pollutants (such as ammonia, amine compounds, heavy metal ions, etc.), including chemisorption, thereby improving the broad-spectrum and selective adsorption performance of the material.

[0011] Forms a uniform dispersion; The dispersion was combined with modified low-density polyethylene, ammonium polyphosphate microcapsules, silicone-modified melamine, and zinc-boron synergist and molded using a multi-zone temperature-controlled extrusion process. The extrusion temperature was set at 185℃, the pulse extrusion frequency was 0.9Hz, and the screw speed was 50rpm, ultimately yielding uniform flame-retardant composite material particles.

[0012] A second aspect of the present invention provides a method for preparing modified municipal solid waste incineration fly ash, which is used to prepare the modified municipal solid waste incineration fly ash described above, comprising the following steps: Fly ash pretreatment: The fly ash from municipal solid waste incineration is mechanically screened to remove coarse impurities with a particle size greater than 1 mm; then, the screened fly ash is finely ground until the average particle size of the fly ash is less than 50 micrometers as detected by a laser particle size analyzer; and the ground fly ash is baked at a temperature of 100°C to 110°C for 1.5 to 2.5 hours to remove physically adsorbed water. Plasma activation: The pretreated fly ash sample is evenly spread and placed in a plasma reactor; the reactor is evacuated to a vacuum level of approximately 50 Pa or less; then, a preset atmosphere is introduced, which is a mixture of inert gas and active gas (the active gas is selected from hydrogen or oxygen), and the pressure inside the reaction chamber is maintained in the range of 100 Pa to 500 Pa; radio frequency or microwave power is applied to excite the plasma, and during the plasma activation process, the temperature of the fly ash sample is maintained in a low temperature range of 150°C to 250°C, and the activation time is controlled in the range of 30 minutes to 60 minutes; after the plasma activation is completed, the reactor is cooled to room temperature under an inert atmosphere, and the activated fly ash sample is removed; mineralization solution preparation: a mineralization solution is prepared, which contains a silicate precursor, a biomolecular template agent, and phosphate or borate; Bionic mineralization: The plasma-activated fly ash sample is slowly added to the mineralization solution while stirring to ensure that the fly ash particles are fully and uniformly dispersed. The solid-liquid mass ratio of the fly ash to the mineralization solution is in the range of 1:10 to 1:20. Under continuous stirring, the pH value of the system is gradually adjusted from the initial state to a weakly alkaline range, i.e., pH 6 to pH 8, by titration or dropwise addition. The pH adjustment process is controlled within about 1 to 3 hours. After adjusting to the target pH value, the reaction is continued to be stirred for about 1 to 2 hours. After the reaction is completed, the solid phase product is separated from the liquid phase by centrifugation or vacuum filtration, and the solid product is repeatedly washed with deionized water about 3 to 5 times until the pH value of the washing solution is close to neutral. Low-temperature calcination: The washed solid product is subjected to low-temperature calcination in an air atmosphere at a heating rate of about 2°C / min to 5°C / min, and the temperature is raised to a target temperature of 200°C to 300°C. The product is then calcined at this temperature for 2 to 3 hours. After calcination, the sample is cooled to room temperature with the furnace to obtain the modified municipal solid waste incineration fly ash.

[0013] In summary, this application includes at least one of the following beneficial technical effects: 1. This invention introduces a plasma activation layer, constructs a silicon oxide coating layer, and synergistically introduces phosphorus oxide or boron oxide, which effectively optimizes the microstructure and surface chemical properties of the material, increases the specific surface area and pore volume of the material, and constructs a multi-level pore structure with synergistic micropores, mesopores and macropores, thereby improving the adsorption capacity and adsorption rate of various waste gas pollutants (such as volatile organic compounds, ammonia, etc.).

[0014] 2. This invention employs plasma-assisted low-temperature activation technology. This technology enables directional modification of fly ash surfaces at lower temperatures, effectively exposing and activating the active sites of fly ash, while significantly reducing energy consumption and secondary pollution. Furthermore, through the deep synergy between plasma activation and biomimetic mineralization technology, the controllable growth of silicon oxides and phosphorus / boron oxides on the activated fly ash surface results in a uniform and dense functional coating layer, avoiding the agglomeration or unevenness problems that may occur in traditional methods.

[0015] 3. This invention employs plasma-assisted low-temperature activation to pretreat fly ash to expose active sites and introduce a plasma activation layer. It also constructs a silicon oxide coating layer on the surface of the activated fly ash using a biomimetic mineralization method, and synergistically introduces phosphorus oxides or boron oxides to form a composite adsorbent material with a multi-level porous structure and specific surface functional groups. This successfully transforms this low-value-added industrial waste into a functional material with high adsorption performance, effectively alleviating the pressure of fly ash storage and environmental risks. Attached Figure Description

[0016] Figure 1 This is a flowchart of the preparation method of this application. Detailed Implementation

[0017] The following is in conjunction with the appendix Figure 1 This application will be described in further detail below.

[0018] Please see the appendix Figure 1 : Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0019] Example 1: Raw material components (by mass fraction): Fly ash matrix: 94.5 parts; Plasma activation layer: 1 piece; Silicon oxide coating: 4 parts; Phosphorus oxides: 0.2 parts.

[0020] Preparation steps: S1. Fly Ash Pretreatment: Take fly ash from municipal solid waste incineration and mechanically screen it to remove coarse impurities with a particle size greater than 1 mm. Then, finely grind the screened fly ash until, as measured by a laser particle size analyzer, the average particle size of the fly ash is less than 25 micrometers. The ground fly ash is then baked at 105°C for 2 hours to remove physically adsorbed water.

[0021] S2. Plasma Activation: The pretreated fly ash sample is evenly spread in a sample tray and placed inside a plasma reactor. The reactor is evacuated to a vacuum level below approximately 50 Pa. Then, a preset atmosphere, a mixture of argon and hydrogen with a volume ratio of 1:9, is introduced to maintain the pressure within the reaction chamber at 300 Pa. Radio frequency power is applied to excite the plasma. During activation, the fly ash sample temperature is maintained at 200°C for 45 minutes. After activation, the reactor is cooled to room temperature under an inert atmosphere, and the activated fly ash sample is removed.

[0022] S3. Preparation of mineralization solution: Weigh an appropriate amount of tetraethyl orthosilicate as a silica precursor, and weigh an appropriate amount of gelatin as a biomolecular template agent. The amount of gelatin added is 1.25 parts relative to the mass of tetraethyl orthosilicate. Additionally, weigh an appropriate amount of disodium hydrogen phosphate as a phosphate, with a molar ratio to tetraethyl orthosilicate of 0.03. Dissolve the above components in deionized water to prepare a mineralization solution.

[0023] S4. Biomimetic Mineralization: The plasma-activated fly ash sample is slowly added to the mineralization solution at a solid-liquid mass ratio of 1:15, and continuous stirring is maintained to ensure sufficient dispersion of the fly ash particles. Under continuous stirring, the pH value of the system is gradually adjusted from the initial state to pH 7 by adding dilute ammonia dropwise, with the pH adjustment process controlled over approximately 2 hours. After adjusting to the target pH value, the reaction is continued with stirring for approximately 1.5 hours. After the reaction is complete, the solid product and liquid phase are separated by centrifugation, and the solid product is repeatedly washed four times with deionized water until the pH value of the washing solution is close to neutral.

[0024] S5. Low-temperature calcination: The washed solid product is placed in a muffle furnace for low-temperature calcination. Calcination is carried out in an air atmosphere at a heating rate of 3.5°C / min, reaching a target temperature of 250°C, and then calcined at this temperature for 2.5 hours. After calcination, the sample is cooled to room temperature with the furnace to obtain the modified municipal solid waste incineration fly ash of Example 1.

[0025] Example 2: Raw material components (by mass fraction): Fly ash matrix: 90 parts; Plasma activation layer: 0.1 part; Silicon oxide coating: 0.5 parts; Phosphorus oxides: 0.01 parts.

[0026] Preparation steps: S1. Fly Ash Pretreatment: Take fly ash from municipal solid waste incineration and mechanically screen it to remove coarse impurities with a particle size greater than 1 mm. Then, finely grind the screened fly ash until, as measured by a laser particle size analyzer, the average particle size of the fly ash is less than 30 micrometers. The ground fly ash is then baked at 100°C for 1.5 hours to remove physically adsorbed water.

[0027] S2. Plasma Activation: The pretreated fly ash sample is evenly spread in a sample tray and placed inside a plasma reactor. The reactor is evacuated to a vacuum level below approximately 50 Pa. Then, a preset atmosphere, a mixture of argon and oxygen with a volume ratio of 0.5:9.5, is introduced to maintain the pressure within the reaction chamber at 100 Pa. Radio frequency power is applied to excite the plasma. During activation, the fly ash sample temperature is maintained at 150°C for 30 minutes. After activation, the reactor is cooled to room temperature under an inert atmosphere, and the activated fly ash sample is removed.

[0028] S3. Preparation of mineralization solution: Weigh an appropriate amount of sodium silicate as a silicate precursor, and weigh an appropriate amount of chitosan as a biomolecular template agent. The amount of chitosan added is 0.5 parts relative to the mass of sodium silicate. Additionally, weigh an appropriate amount of boric acid as a borate, with a molar ratio of 0.01 to sodium silicate. Dissolve the above components in deionized water to prepare a mineralization solution.

[0029] S4. Biomimetic Mineralization: The plasma-activated fly ash sample is slowly added to the mineralization solution at a solid-liquid mass ratio of 1:10, and continuous stirring is maintained to ensure full dispersion of the fly ash particles. Under continuous stirring, the pH value of the system is gradually adjusted from the initial state to pH 6 by adding dilute acid (such as dilute hydrochloric acid), with the pH adjustment process controlled over approximately 1 hour. After adjusting to the target pH value, the reaction is continued with stirring for approximately 1 hour. After the reaction is completed, the solid product and liquid phase are separated by vacuum filtration, and the solid product is repeatedly washed three times with deionized water until the pH value of the washing solution is close to neutral.

[0030] S5. Low-temperature calcination: The washed solid product is placed in a muffle furnace for low-temperature calcination. Calcination is carried out in an air atmosphere at a heating rate of 2°C / min, reaching a target temperature of 200°C, and then held at this temperature for 2 hours. After calcination, the sample is cooled to room temperature with the furnace to obtain the modified municipal solid waste incineration fly ash of Example 2.

[0031] Example 3: Raw material components (by mass fraction): Fly ash matrix: 99 parts; Plasma activation layer: 2 parts; Silicon oxide coating: 8 parts; Phosphorus oxides: 0.5 parts.

[0032] Preparation steps: S1. Fly Ash Pretreatment: Take fly ash from municipal solid waste incineration and mechanically screen it to remove coarse impurities with a particle size greater than 1 mm. Then, finely grind the screened fly ash until, as measured by a laser particle size analyzer, the average particle size of the fly ash is less than 20 micrometers. The ground fly ash is then baked at 110°C for 2.5 hours to remove physically adsorbed water.

[0033] S2. Plasma Activation: The pretreated fly ash sample is evenly spread in a sample tray and placed inside a plasma reactor. The reactor is evacuated to a vacuum level below approximately 50 Pa. Then, a preset atmosphere, a mixture of argon and hydrogen with a volume ratio of 2:8, is introduced to maintain the pressure within the reaction chamber at 500 Pa. A microwave power supply is applied to excite the plasma. During activation, the fly ash sample temperature is maintained at 250°C for 60 minutes. After activation, the reactor is cooled to room temperature under an inert atmosphere, and the activated fly ash sample is removed.

[0034] S3. Preparation of mineralization solution: Weigh an appropriate amount of tetraethyl orthosilicate as a silica precursor, and weigh an appropriate amount of gelatin as a biomolecular template agent. The amount of gelatin added is 2 parts relative to the mass of tetraethyl orthosilicate. Additionally, weigh an appropriate amount of potassium dihydrogen phosphate as a phosphate, with a molar ratio of 0.05 to tetraethyl orthosilicate. Dissolve the above components in deionized water to prepare a mineralization solution.

[0035] S4. Biomimetic Mineralization: The plasma-activated fly ash sample is slowly added to the mineralization solution at a solid-liquid mass ratio of 1:20, and continuous stirring is maintained to ensure full dispersion of the fly ash particles. Under continuous stirring, the pH value of the system is gradually adjusted from the initial state to pH 8 by adding dilute alkaline water (such as sodium hydroxide solution), with the pH adjustment process controlled over approximately 3 hours. After adjusting to the target pH value, the reaction is continued with stirring for approximately 2 hours. After the reaction is completed, the solid product and liquid phase are separated by centrifugation, and the solid product is repeatedly washed 5 times with deionized water until the pH value of the washing solution is close to neutral.

[0036] S5. Low-temperature calcination: The washed solid product is placed in a muffle furnace for low-temperature calcination. Calcination is carried out in an air atmosphere at a heating rate of 5°C / min, reaching a target temperature of 300°C, and then held at this temperature for 3 hours. After calcination, the sample is cooled to room temperature with the furnace to obtain the modified municipal solid waste incineration fly ash of Example 3.

[0037] Comparative Example 1: The difference between this comparative example and Example 1 is that the plasma activation step is omitted, while the rest are the same.

[0038] Comparative Example 2: The difference between this comparative example and Example 1 is that no phosphate or borate was added in the mineralization solution preparation step; all other steps are the same.

[0039] Comparative Example 3: The difference from Example 1 is that no phosphate or borate was added in the mineralization solution preparation step of this comparative example.

[0040] Experiment 1: Experimental objective: To quantify and compare the adsorption capacity and adsorption efficiency of Example 1 and Comparative Example 1 for a specific pollutant through a simulated waste gas adsorption experiment.

[0041] Experimental steps: Adsorbent preparation: The samples of Example 1 and Comparative Example 1 were dried at 100°C for 2 hours to remove surface-adsorbed moisture and then cooled to room temperature.

[0042] Accurately weigh equal masses (e.g., 1.0 g each) of the sample from Example 1 and the sample from Comparative Example 1, and uniformly pack them into two identical adsorption columns, ensuring consistent packing density.

[0043] Adsorption system setup: The adsorption column is connected to a simulated waste gas adsorption experimental device. This device includes a gas cylinder (carrier gas, pollutant gas), a gas flow controller, a mixing chamber, a temperature control device, an adsorption column, and an online gas concentration analyzer. Ensure all pipe connections are properly sealed and there are no gas leaks.

[0044] Adsorption experiment parameter settings: Set the adsorption temperature to 25℃, the initial concentration of pollutant gas to 100ppm (volume fraction), and the total gas flow rate to 100mL / min. Set the flow ratio of carrier gas to pollutant gas to precisely control the pollutant concentration.

[0045] Adsorption experiment procedure: Blank operation: Without connecting the adsorption column, introduce pollutant gas of a set concentration and record the initial pollutant concentration using an online gas concentration analyzer as a baseline value.

[0046] Sample adsorption: The adsorption columns of Example 1 and Comparative Example 1 were connected to the adsorption system, respectively. A pollutant gas of a set concentration was introduced, and an online gas concentration analyzer was started simultaneously to monitor the pollutant concentration at the outlet of the adsorption column in real time.

[0047] Breakthrough curve plotting: Continuously record the change in outlet pollutant concentration over time until the outlet concentration reaches or approaches the initial concentration, i.e., adsorbent saturation. Plot the adsorption breakthrough curve (relationship between outlet concentration and time) based on the real-time data.

[0048] Calculate adsorption capacity: Based on the breakthrough curve, calculate the breakthrough adsorption capacity and saturation adsorption capacity of the adsorbent. The calculation formula is based on gas flow rate, initial concentration, outlet concentration, and adsorption time.

[0049] The experimental results are shown in Table 1.

[0050] Table 1: Results of Adsorption Performance Comparison Test As shown in Table 1, the sample of Example 1, after plasma activation treatment, exhibits significantly better adsorption capacity and adsorption rate for the target pollutant than that of Comparative Example 1. This result strongly confirms that the plasma-assisted low-temperature activation technology used in this invention improves the adsorption performance of the material by modifying the surface of the fly ash matrix.

[0051] In Comparative Example 1, the fly ash substrate without plasma activation typically exhibits a dense passivation layer and limited active sites, restricting effective contact with pollutant molecules and chemisorption. Even with subsequent biomimetic mineralization, the formation of the silicon oxide coating may be uneven due to the lack of a sufficiently activated substrate, and the overall pore structure construction efficiency of the material is limited. In contrast, Example 1 introduced a plasma activation step prior to biomimetic mineralization. The non-thermal effects of high-energy particles (such as active radicals, electrons, and ions) in plasma enable selective physical etching and chemical modification of the fly ash surface at relatively low temperatures (150°C–250°C). This process effectively strips away the passivation layer on the fly ash surface, exposing more original active sites and in-situ inducing and activating new surface functional groups, such as hydroxyl, carboxyl, or active carbon dots.

[0052] Therefore, the active layer formed by plasma activation promotes the uniform and dense growth of silicon oxides and phosphorus oxides (or boron oxides) on the fly ash surface. The surface functional groups introduced by plasma activation directly participate in the adsorption of pollutant molecules, increasing the density and activity of adsorption sites. This invention achieves the transformation of municipal solid waste incineration fly ash from an inert carrier to a highly efficient adsorbent material through the synergistic effect of plasma activation and biomimetic mineralization.

[0053] Experiment 2: Experimental objective: To quantify and compare the adsorption capacity and adsorption selectivity of Example 1 and Comparative Example 2 for specific pollutants through a simulated waste gas adsorption experiment.

[0054] Experimental steps: Adsorbent preparation: The samples of Example 1 and Comparative Example 2 were dried at 100°C for 2 hours to remove the surface-adsorbed moisture and then cooled to room temperature. Accurately weigh equal masses (e.g., 1.2 g each) of the sample from Example 1 and the sample from Comparative Example 2, and uniformly pack them into two identical adsorption columns, ensuring consistent packing density.

[0055] Adsorption system setup: Connect the adsorption column to the simulated waste gas adsorption experimental device. This device includes a gas cylinder (carrier gas and pollutant gas), a gas flow controller, a mixing chamber, a temperature control device, an adsorption column, and an online gas concentration analyzer. Ensure that all pipeline connections are well sealed and there is no gas leakage.

[0056] Adsorption experiment parameter settings: Set the adsorption temperature to 30℃, the initial concentration of the target pollutant gas to 50ppm (volume fraction), and the total gas flow rate to 120mL / min. Set the flow ratio of carrier gas to pollutant gas to control the pollutant concentration.

[0057] Adsorption experiment procedure: Blank operation: Without connecting the adsorption column, introduce pollutant gas of a set concentration and record the initial pollutant concentration using an online gas concentration analyzer as a baseline value.

[0058] Sample adsorption: The adsorption columns of Example 1 and Comparative Example 2 were connected to the adsorption system, respectively. A pollutant gas of a set concentration was introduced, and an online gas concentration analyzer was started simultaneously to monitor the pollutant concentration at the outlet of the adsorption column in real time.

[0059] Breakthrough curve plotting: Continuously record the change in outlet pollutant concentration over time until the outlet concentration reaches or approaches the initial concentration, i.e., adsorbent saturation. Plot the adsorption breakthrough curve (relationship between outlet concentration and time) based on the real-time data.

[0060] Calculate adsorption capacity: Based on the breakthrough curve, calculate the breakthrough adsorption capacity and saturation adsorption capacity of the adsorbent. The calculation formula is based on gas flow rate, initial concentration, outlet concentration, and adsorption time.

[0061] The experimental results are shown in Table 2.

[0062] Table 2: Adsorption Performance Comparison Test Results As shown in Table 2, compared with Comparative Example 2 which did not introduce phosphorus oxides or boron oxides, the sample of Example 1 containing this functional component exhibited a significant increase in adsorption capacity for the target pollutant. This result fully verifies the effectiveness of introducing phosphorus or boron elements into the material composition design of this invention in optimizing the surface chemical properties and adsorption activity of the adsorbent.

[0063] While the sample in Comparative Example 2 possessed a basic silicon oxide coating and a hierarchical porous structure, its surface lacked chemical sites capable of efficiently interacting with specific pollutants. When phosphorus (or boron) is introduced in oxide form, it can covalently bond to the silicon oxide coating, forming silicon-phosphorus composite oxides or silicon-boron composite oxides. These composite oxides introduce additional Lewis acid sites or Brønsted acid sites onto the material surface, significantly altering the electron distribution and acid-base properties of the material. For example, for alkaline pollutants such as ammonia, these newly added acidic sites can provide strong chemisorption, firmly capturing pollutant molecules through acid-base interactions (such as hydrogen bonds or coordination bonds).

[0064] Therefore, the introduction of phosphorus oxides (or boron oxides) improves the selective adsorption capacity of modified fly ash materials for specific types of pollutants (such as nitrogen-, sulfur-, or chlorine-containing organic compounds), effectively removing specific harmful components from complex systems.

[0065] Experiment 3: Experimental objective: By simulating waste gas adsorption experiments, the adsorption capacity and adsorption rate of specific pollutants of Example 1 and Comparative Example 3 were quantitatively compared.

[0066] Experimental steps: Adsorbent preparation: The samples of Example 1 and Comparative Example 3 were dried at 100°C for 2 hours to remove the surface-adsorbed moisture and then cooled to room temperature. Accurately weigh equal masses (e.g., 1.1 g each) of the sample from Example 1 and the sample from Comparative Example 3, and uniformly pack them into two identical adsorption columns, ensuring consistent packing density.

[0067] Adsorption system setup: Connect the adsorption column to the simulated waste gas adsorption experimental device. This device includes a gas cylinder (carrier gas and pollutant gas), a gas flow controller, a mixing chamber, a temperature control device, an adsorption column, and an online gas concentration analyzer. Ensure that all pipeline connections are well sealed and there is no gas leakage.

[0068] Adsorption experiment parameter settings: The adsorption temperature was set to 35℃, the initial concentration of the target pollutant gas was set to 80ppm (volume fraction), and the total gas flow rate was set to 110mL / min. Set the flow ratio of carrier gas to pollutant gas to control the pollutant concentration.

[0069] Adsorption experiment procedure: Blank operation: Without connecting the adsorption column, introduce pollutant gas of a set concentration and record the initial pollutant concentration using an online gas concentration analyzer as a baseline value.

[0070] Sample adsorption: The adsorption columns of Example 1 and Comparative Example 3 were connected to the adsorption system, respectively. A pollutant gas of a set concentration was introduced, and an online gas concentration analyzer was started simultaneously to monitor the pollutant concentration at the outlet of the adsorption column in real time.

[0071] Breakthrough curve plotting: Continuously record the change in outlet pollutant concentration over time until the outlet concentration reaches or approaches the initial concentration, i.e., adsorbent saturation. Plot the adsorption breakthrough curve (relationship between outlet concentration and time) based on the real-time data.

[0072] Calculate adsorption capacity: Based on the breakthrough curve, calculate the breakthrough adsorption capacity and saturation adsorption capacity of the adsorbent. The calculation formula is based on gas flow rate, initial concentration, outlet concentration, and adsorption time.

[0073] The experimental results are shown in Table 3.

[0074] Table 3: Test data on extrusion stability and molding accuracy As shown in Table 3, by comparing the adsorption performance of Example 1 (silicon oxide coating content within the range specified in the invention) and Comparative Example 3 (silicon oxide coating content below the lower limit), insufficient silicon oxide coating content will significantly reduce the adsorption capacity and efficiency of the material for the target pollutant.

[0075] In the biomimetic mineralization process, the plasma-activated fly ash surface serves as a nucleation substrate, guiding the polymerization and growth of silica precursors. When the mass fraction of the silicon oxide coating layer is insufficient, as shown in Comparative Example 3, the resulting coating layer may be discontinuous, not dense, or insufficient in thickness. This incomplete coating not only fails to adequately cover the inactive areas of the fly ash matrix surface, but more importantly, it cannot effectively form and stabilize micropores, mesopores, and macropores in the hierarchical pore structure, leading to a significant decrease in the specific surface area and pore volume of the material. The number and accessibility of adsorption sites are severely limited, making it difficult for pollutant molecules to effectively enter and diffuse into the adsorbent, thus hindering the adsorption process.

[0076] Therefore, the presence of silicon oxide coating within a specific mass fraction range ensures that the modified fly ash material can form a complete and highly interconnected hierarchical porous structure, providing a huge physical adsorption space for pollutants and optimizing the mass transfer path, enabling pollutant molecules to quickly diffuse to the active adsorption sites. By controlling the content of silicon oxide, the uniform construction of the coating and the effective formation of the hierarchical porous structure are ensured, thereby enabling the deep functionalization of municipal solid waste incineration fly ash.

[0077] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be covered within the scope of protection of this application.

Claims

1. A modified fly ash from municipal solid waste incineration, characterized in that, The components include the following parts by mass: Fly ash matrix: 90-99 parts; Plasma activation layer: 0.1-2 parts; Silicon oxide coating: 0.5-8 parts; Phosphorus oxides: 0.01-0.5 parts.

2. The modified municipal solid waste incineration fly ash according to claim 1, characterized in that, The plasma activation layer is formed by activation with reducing atmosphere plasma or oxidizing atmosphere plasma.

3. The modified municipal solid waste incineration fly ash according to claim 1, characterized in that, The silicon oxide coating layer is amorphous silicon dioxide, and the phosphorus oxide is covalently bonded to the silicon oxide coating layer.

4. The modified municipal solid waste incineration fly ash according to claim 1, characterized in that, The modified municipal solid waste incineration fly ash has a multi-level pore structure consisting of micropores, mesopores, and macropores, with the macropore diameter ranging from 50 nanometers to 500 nanometers.

5. A method for preparing modified municipal solid waste incineration fly ash, applied to the modified municipal solid waste incineration fly ash described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Mechanically screen the fly ash from municipal solid waste incineration to remove impurities with a particle size greater than 1 mm, grind it to reduce the average particle size of the fly ash to less than 50 micrometers, and bake it at a temperature of 100℃-110℃ for 1.5 hours to 2.5 hours. S2. The ground fly ash is subjected to a mixed atmosphere of inert gas and active gas at a temperature of 150℃-250℃ and a pressure range of 100Pa-500Pa, and plasma activation is applied for 30 minutes-60 minutes. S3. Prepare mineralization solutions of silica precursors, biomacromolecule templates, and phosphates or borates. S4. Disperse the plasma-activated fly ash in the mineralization solution, induce mineralization through pH gradient, and then separate and wash. S5. The mineralized fly ash is calcined at a low temperature of 200℃-300℃ for 2-3 hours to obtain the final product.

6. The method for preparing modified municipal solid waste incineration fly ash according to claim 5, characterized in that, In step S1, the average particle size of the fly ash from municipal solid waste incineration is detected by a laser particle size analyzer.

7. The preparation process of modified municipal solid waste incineration fly ash according to claim 5, characterized in that, In step S2, the inert gas is argon, and the active gas is hydrogen or oxygen. The volume ratio of hydrogen to argon can be selected within the range of 0.5:9.5-2:8; The volume ratio of oxygen to argon can be selected within the range of 0.5:9.5 to 2:

8.

8. The preparation process of modified municipal solid waste incineration fly ash according to claim 5, characterized in that, In step S3, the silica precursor is tetraethyl orthosilicate or sodium silicate, and the biomolecular template agent is gelatin or chitosan.

9. The preparation process of modified municipal solid waste incineration fly ash according to claim 5, characterized in that, In step S4, the molar ratio of the phosphate or borate to the silica precursor is 0.01-0.05.

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