A modified biomass charcoal-based material based on copper loading / prussian blue composite and a preparation method and application thereof

Abstract

This invention discloses a modified biomass carbon-based material based on copper-supported / Prussian blue composite, its preparation method, and its application, belonging to the field of environmental engineering and waste gas treatment technology. The preparation method of the modified biomass carbon-based material based on copper-supported / Prussian blue composite includes the following steps: co-pyrolyzing phytic acid with a biomass precursor to obtain a high specific surface area biomass carbon matrix material; modifying the biomass carbon matrix material with copper source loading and then calcining it to obtain a copper-supported modified biomass carbon material; adding the copper-supported modified biomass carbon material and a Prussian blue pre-nucleation solution to water, stirring, centrifuging to separate the precipitate, and washing to obtain the modified biomass carbon-based material based on copper-supported / Prussian blue composite. The modified biochar-based material based on copper-supported / Prussian blue composite obtained by this invention combines the high specific surface area and hierarchical porous structure of modified biochar, the Lewis acid coordination ability of copper active sites, and the confinement and adsorption enhancement effect of the Prussian blue framework, thereby achieving the synergistic effect of physical adsorption and chemical adsorption, and thus effectively improving the material's ability to capture ammonia.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering and waste gas treatment technology, and in particular relates to a modified biomass carbon-based material based on copper-supported / Prussian blue composite, its preparation method and application. Background Technology

[0002] Ammonia (NH3), a typical nitrogen-containing volatile pollutant, is widely derived from livestock and poultry farming, wastewater treatment, and industrial waste gas emissions. It not only causes odor pollution but also participates in the formation of secondary particulate matter in the atmosphere, affecting air quality and human health. For ammonia treatment, compared with other purification technologies, adsorption does not have the problems of volatility, viscosity, or corrosiveness. The adsorption process does not produce waste liquid, does not require additional oxidants, and operates under mild conditions, making it suitable for treating gases with low concentrations and high purification requirements. Based on these advantages, adsorption is considered one of the deep ammonia removal technologies with promising industrial applications. The key to ammonia adsorption purification lies in high-performance adsorbents; however, existing adsorption materials still have significant shortcomings in terms of efficiency and stability.

[0003] Unmodified biochar materials typically suffer from low specific surface area and underdeveloped pore structure, limiting their application as carriers of functional components. Phytic acid, during co-pyrolysis, can etch the carbon structure, promoting the formation and development of pores in biochar and thus increasing its specific surface area. Furthermore, as a bio-based organic acid, phytic acid exhibits better green and environmentally friendly properties compared to some traditional acid treatment agents. However, the adsorption of ammonia by phytic acid-modified biochar still primarily relies on physical adsorption mechanisms, with limited surface chemically active sites, resulting in limited selectivity and adsorption capacity enhancement for polar molecules. Since NH3 molecules are Brønsted bases and also Lewis bases, they can react not only with acidic sites but also with metal salts to form complexes. Therefore, further loading copper onto a high-specific-surface-area phytic acid-modified biochar matrix can utilize copper ions as Lewis acid centers to form multi-site coordination with ammonia molecules, thereby enhancing the material's interaction with ammonia and increasing its adsorption capacity. However, in single-metal doped systems, the metal is prone to agglomeration, the active sites are unevenly distributed, and the lack of ordered pore structure to confine and regulate the mass transfer of gas molecules limits the actual adsorption efficiency.

[0004] On the other hand, Prussian blue (PB) and its analogues, as a class of metal-cyanide bridged coordination compounds, possess a regular cubic crystal structure and open framework pores, containing abundant metal coordination centers that can interact with polar gas molecules. However, Prussian blue materials still have certain limitations when used alone, such as easy particle aggregation and poor dispersibility. Aggregation may lead to a decrease in effective specific surface area, insufficient exposure of active sites, and affect adsorption performance. Furthermore, traditional Prussian blue and its analogues also suffer from relatively limited pore size and specific surface area, which is not conducive to the diffusion of adsorbate molecules into the material interior, thus restricting their widespread application in the field of adsorption materials. Therefore, how to construct a composite material system that combines a high specific surface area carbon-based framework, uniformly dispersed copper active sites, and a stably loaded PB framework structure to achieve the synergistic effect of hierarchical pore structure and multiple active centers is a technical problem that urgently needs to be solved in the field of efficient ammonia adsorption. Currently, there is a lack of a preparation method that uses copper doping to regulate the carbon-based structure and further in-situ composites with PB to form a synergistic adsorption system. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a modified biomass char-based material based on a copper-supported / Prussian blue composite, its preparation method, and its applications. First, a porous biomass char matrix is ​​prepared by co-pyrolyzing waste biomass and phytic acid under an inert atmosphere. Then, copper is uniformly loaded onto the biomass char matrix through metal salt impregnation and heat treatment, constructing stable active sites on the surface of the biomass char matrix. Furthermore, a Prussian blue framework structure is introduced through in-situ composite technology, forming a modified biomass char-based material with hierarchical pores and dual metal coordination centers. This material combines the high specific surface area of ​​modified biomass char, the coordination adsorption capacity of copper active sites, and the confinement effect of the open framework of Prussian blue, achieving a synergistic enhancement of physical and chemical adsorption, thereby significantly improving the ammonia adsorption capacity and stability.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a modified biomass carbon-based material based on copper-supported / Prussian blue composite, comprising the following steps: co-pyrolyzing phytic acid with a biomass precursor to obtain a high specific surface area carbon matrix material; modifying the biomass carbon matrix material with copper source loading and then calcining it to obtain a copper-supported modified biomass carbon material; adding the copper-supported modified biomass carbon material and a Prussian blue pre-nucleation solution to water, stirring, centrifuging to separate the precipitate and washing it to obtain the modified biomass carbon-based material based on copper-supported / Prussian blue composite.

[0007] Furthermore, the ratio of the copper-supported modified biochar material, Prussian blue prenuclearization solution, and water is 0.8 g: 200 mL: 300 mL.

[0008] Furthermore, the preparation method of the copper-loaded modified biochar material includes the following steps: under an inert gas atmosphere, the biomass precursor is co-pyrolyzed with phytic acid to obtain a high specific surface area biochar material; the biochar material and copper source are added to ultrapure water, and the modified biochar material is modified by an equal volume impregnation method; the modified biochar material is taken out, dried, and then calcined to obtain the copper-loaded modified biochar material.

[0009] Furthermore, the biomass precursor is selected from sugarcane bagasse, bamboo powder, or camellia fruit shell; The copper source is anhydrous copper chloride.

[0010] Furthermore, the mass ratio of the biochar matrix material to the copper source is 1:0.423; the co-pyrolysis temperature is 600 °C, and the time is 2 h. The impregnation time is 12 hours; the specific operation of calcination is as follows: under an inert gas atmosphere, the temperature is increased at a rate of 5 °C / min, and the pyrolysis is carried out at a constant temperature of 350 °C for 2 hours.

[0011] Furthermore, the Prussian blue prenucleation solution is a mixed aqueous solution of ferric chloride hexahydrate and potassium ferrocyanide trihydrate.

[0012] Furthermore, the ratio of ferric chloride hexahydrate, potassium ferrocyanide trihydrate, and water is 1.2 g: 1.6 g: 200 mL.

[0013] This invention uses waste biomass such as sugarcane bagasse, bamboo powder, or camellia fruit shells as raw materials. A high specific surface area porous carbon framework is constructed by co-pyrolysis with phytic acid under an inert atmosphere. Based on this, uniform loading of metallic copper is achieved through equal-volume impregnation, introducing well-dispersed active sites. Furthermore, a Prussian blue framework structure is composited onto the surface of the copper-loaded modified biomass char via a liquid-phase in-situ composite method, forming a composite system synergistically constructed with a carbon-based porous structure, copper active site centers, and a coordination framework. This method features clear process steps, controllable parameters, and the copper loading and Prussian blue composite amount can be adjusted by the precursor ratio. The metal is uniformly dispersed and the interfacial bonding is stable, preventing agglomeration or detachment. The overall preparation process utilizes widely available and inexpensive raw materials, exhibits good reproducibility, and demonstrates excellent scalability and industrial application potential.

[0014] This invention addresses the limitations of existing biomass-based adsorbent materials, including limited adsorption capacity, single active sites, limited modification methods, and insufficient mass transfer efficiency. It proposes a method for preparing modified biomass-based materials based on a copper-supported / Prussian blue composite, achieving synergistic optimization of pore structure regulation and surface active site construction. Specifically, the phytic acid-modified biomass-based matrix provides a high specific surface area and a hierarchical pore structure, Prussian blue constructs ordered coordination channels and increases the mesopore ratio, and metallic Cu provides strong coordination active centers. The synergistic effect of these three components significantly enhances ammonia adsorption performance. Furthermore, this material system retains a certain adsorption capacity even after changing the metal species (e.g., Mn). This invention not only realizes the high-value utilization of biomass resources but also provides new ideas for the design of high-performance ammonia adsorbent materials.

[0015] Secondly, the present invention provides a modified biomass carbon-based material based on copper-supported / Prussian blue composite, which is prepared by the aforementioned preparation method.

[0016] The modified biomass carbon-based material prepared by this invention based on copper-supported / Prussian blue composite has a large specific surface area and abundant pore structure. The copper active sites on the support are uniformly dispersed, and the face-centered cubic (FCC) crystal structure of the supported Prussian blue is not affected. The structure is stable and has excellent ammonia adsorption performance.

[0017] Thirdly, the present invention provides an application of the above-mentioned modified biomass carbon-based material based on copper-supported / Prussian blue composite in ammonia adsorption and treatment.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects: The modified biochar-based material based on copper-supported / Prussian blue composite prepared in this invention combines the high specific surface area and hierarchical porous structure of modified biochar, the Lewis acidic coordination ability of copper active sites, and the confinement and adsorption enhancement effect of the Prussian blue framework, achieving a synergistic effect of physical and chemical adsorption, thereby effectively improving the material's ammonia capture capacity. Under conditions of 500 ppm ammonia concentration and 500 mL / min flow rate, the material exhibits good ammonia adsorption performance and stability. Phytic acid activation increases the specific surface area of ​​the biochar, providing more ample loading space and a more developed pore structure for the copper-supported / Prussian blue composite. Copper loading enhances the material's surface electronic regulation ability and ammonia molecule coordination binding ability. The composite of the Prussian blue framework further increases the number of accessible active centers and optimizes the gas mass transfer path, thus significantly improving ammonia adsorption capacity and purification efficiency. Simultaneously, the material exhibits structural stability and good cycle performance, making it suitable for livestock and poultry farming, wastewater treatment, and industrial waste gas purification. Attached Figure Description

[0019] To more clearly illustrate the embodiments of the present invention or existing technical solutions, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The N2 adsorption-desorption isotherm and pore size distribution of Cu@PSB / PB prepared in Example 1 are shown. Figure 2 The XRD pattern of Cu@PSB / PB prepared in Example 1; Figure 3 Infrared spectrum of Cu@PSB / PB prepared in Example 1; Figure 4 The adsorption breakthrough time curve of Cu@PSB / PB prepared in Example 1; Figure 5 The graph shows the adsorption cycle regeneration performance of Cu@PSB / PB prepared in Example 1. Figure 6 The adsorption breakthrough time curve of PSB / PB prepared for Comparative Example 1; Figure 7 The infrared spectrum of PSB / PB prepared in Comparative Example 1; Figure 8 The adsorption breakthrough time curve of Cu@PSB prepared for Comparative Example 2 is shown. Figure 9 The adsorption breakthrough time curve of Mn@PSB / PB prepared for Comparative Example 3; Figure 10 The adsorption breakthrough time curve of Cu@PBP / PB prepared in Example 2; Figure 11 The adsorption breakthrough time curve of Cu@PCS / PB prepared in Example 3; Figure 12 The graph shows a comparison of the ammonia saturation adsorption capacity of the biochar materials prepared in Example 1, Comparative Example 3, Comparative Example 1 and Comparative Example 2. Detailed Implementation

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0023] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0024] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0025] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0026] To facilitate understanding, the following technical terms will be explained.

[0027] In this invention, the equal-volume impregnation does not mean that the volume of the biochar material and the volume of water are the same. Instead, the volume of water added is determined based on the specific surface area of ​​the material, that is, the volume of water consumed after the material is fully saturated. The equal-volume impregnation method is a method for preparing supported catalysts by making the volume of the impregnation liquid equal to the pore volume of the support. This method can precisely control the loading of active components and avoid migration and aggregation.

[0028] The room temperature in this invention refers to 25±2℃.

[0029] Example 1: A method for preparing modified bagasse carbon-based materials based on copper-supported / Prussian blue composite. (1) Under a nitrogen atmosphere, bagasse powder that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h. The resulting PSB (biochar matrix material) is a bagasse carbon matrix material with a high specific surface area. (2) Take 1.0 g of PSB prepared in step (1) and 0.423 g of anhydrous copper chloride, add them to 3.5 mL of ultrapure water, sonicate for 1 h until fully mixed, and then impregnate at room temperature for 12 h. After that, take out the PSB and vacuum dry it at 80 °C for 12 h. (3) Transfer the material after vacuum drying in step (2) to a quartz boat, and perform programmed calcination at a rate of 5 °C / min under a nitrogen atmosphere. Then, perform constant temperature pyrolysis at 350 °C for 2 h to obtain Cu@PSB (copper-supported modified bagasse carbon material). (4) Take 1.2 g of ferric chloride hexahydrate and 1.6 g of potassium ferrocyanide trihydrate and add them to 200 mL of ultrapure water. Mix and stir at 45 °C for 15 min to obtain Prussian blue prenucleation solution; (5) Take 0.8 g of Cu@PSB prepared in step (3) and add it to 300 mL of ultrapure water for pre-dispersion. Then add the Prussian blue pre-nucleation solution prepared in step (4). The volume of the resulting mixed solution is 500 mL. Stir the mixed solution for 3 h, centrifuge to obtain the precipitate, and wash the precipitate three times with deionized water and anhydrous ethanol respectively to obtain Cu@PSB / PB (a modified bagasse carbon-based material based on copper-supported / Prussian blue composite).

[0030] Example 2: A method for preparing modified bamboo charcoal-based materials based on copper-supported / Prussian blue composite. (1) Under a nitrogen atmosphere, bamboo powder that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h to obtain PBP (biochar matrix material) as a high specific surface area bamboo char matrix material. (2) Take 1.0 g of PBP prepared in step (1) and 0.423 g of anhydrous copper chloride, add them to 3.5 mL of ultrapure water, sonicate for 1 h until fully mixed, and then impregnate at room temperature for 12 h. After that, take out the PBP and vacuum dry it at 80 °C for 12 h. (3) Transfer the material after vacuum drying in step (2) to a quartz boat, and calcine it at a programmed temperature rise rate of 5 °C / min under a nitrogen atmosphere. Then, pyrolyze it at a constant temperature of 350 °C for 2 h to obtain Cu@PBP (copper-loaded modified bamboo charcoal material). (4) Take 1.2 g of ferric chloride hexahydrate and 1.6 g of potassium ferrocyanide trihydrate and add them to 200 mL of ultrapure water. Mix and stir at 45 °C for 15 min to obtain Prussian blue prenucleation solution; (5) Take 0.8 g of Cu@PBP prepared in step (3) and add it to 300 mL of ultrapure water for pre-dispersion. Then add the Prussian blue pre-nucleation solution prepared in step (4). The volume of the resulting mixed solution is 500 mL. Stir the mixed solution for 3 h, centrifuge to obtain the precipitate, and wash the precipitate three times with deionized water and anhydrous ethanol respectively to obtain Cu@PBP / PB (a modified bamboo charcoal-based material based on copper-supported / Prussian blue composite).

[0031] Example 3: A method for preparing a modified Camellia oleifera fruit shell carbon-based material based on copper-supported / Prussian blue composite. (1) Under a nitrogen atmosphere, the camellia fruit shell that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h to obtain PCS (biochar matrix material) as a high specific surface area camellia fruit shell carbon matrix material. (2) Take 1.0 g of PCS prepared in step (1) and 0.423 g of anhydrous copper chloride, add them to 3.5 mL of ultrapure water, sonicate for 1 h until fully mixed, and then impregnate at room temperature for 12 h. After that, take out the PCS and vacuum dry it at 80 °C for 12 h. (3) Transfer the material after vacuum drying in step (2) to a quartz boat, and perform programmed calcination at a rate of 5 °C / min under a nitrogen atmosphere. Then, perform constant temperature pyrolysis at 350 °C for 2 h to obtain Cu@PCS (copper-supported modified camellia fruit shell carbon material). (4) Take 1.2 g of ferric chloride hexahydrate and 1.6 g of potassium ferrocyanide trihydrate and add them to 200 mL of ultrapure water. Mix and stir at 45 °C for 15 min to obtain Prussian blue prenucleation solution; (5) Take 0.8 g of Cu@PCS prepared in step (3) and add it to 300 mL of ultrapure water for pre-dispersion. Then add the Prussian blue pre-nucleation solution prepared in step (4). The volume of the resulting mixed solution is 500 mL. Stir the mixed solution for 3 h, centrifuge to obtain the precipitate, and wash the precipitate 3 times with deionized water and anhydrous ethanol respectively to obtain Cu@PCS / PB (a modified camellia fruit shell carbon-based material based on copper-supported / Prussian blue composite).

[0032] Comparative Example 1 (1) Under a nitrogen atmosphere, sugarcane bagasse powder that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h to obtain PSB (biochar matrix material) as a high specific surface area sugarcane bagasse carbon matrix material. (2) Take 1.2 g of ferric chloride hexahydrate and 1.6 g of potassium ferrocyanide trihydrate and add them to 200 mL of ultrapure water. Mix and stir at 45 °C for 15 min to obtain Prussian blue prenucleation solution; (3) Take 0.8 g of PSB prepared in step (1) and add it to 300 mL of ultrapure water for pre-dispersion. Then add the Prussian blue pre-nucleation solution prepared in step (2) to obtain a mixed solution volume of 500 mL. Stir the mixed solution for 3 h, centrifuge to obtain the precipitate, and wash the precipitate 3 times with deionized water and anhydrous ethanol respectively to obtain PSB / PB (Prussian blue / bagasse modified bagasse carbon composite material).

[0033] Comparative Example 2 (1) Under a nitrogen atmosphere, sugarcane bagasse powder that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h to obtain PSB (biochar matrix material) as a high specific surface area sugarcane bagasse carbon matrix material. (2) Take 1.0 g of PSB prepared in step (1) and 0.423 g of anhydrous copper chloride, add them to 3.5 mL of ultrapure water, sonicate for 1 h until fully mixed, and then impregnate at room temperature for 12 h. After that, take out the PSB and vacuum dry it at 80 °C for 12 h. (3) Transfer the material after vacuum drying in step (2) to a quartz boat, and perform a second calcination at a programmed temperature rise rate of 5 °C / min under a nitrogen atmosphere. Then, perform constant temperature pyrolysis at 350 °C for 2 h to obtain Cu@PSB (copper-loaded modified bagasse carbon material).

[0034] Comparative Example 3 (1) Under a nitrogen atmosphere, sugarcane bagasse powder that has passed through a 60-mesh sieve and phytic acid are placed in a tube furnace at a mass ratio of 1:1 and pyrolyzed at a constant temperature of 600 °C for 2 h to obtain PSB (biochar matrix material) as a high specific surface area sugarcane bagasse carbon matrix material. (2) Take 1.0 g of PSB prepared in step (1) and 0.458 g of anhydrous manganese chloride, add them to 3.5 mL of ultrapure water, sonicate for 1 h until fully mixed, and then impregnate at room temperature for 12 h. After that, take out the PSB and vacuum dry it at 80 °C for 12 h. (3) Transfer the material after vacuum drying in step (2) to a quartz boat, and perform a second calcination at a programmed temperature rise rate of 5 °C / min under a nitrogen atmosphere. Then, perform constant temperature pyrolysis at 350 °C for 2 h to obtain Mn@PSB (manganese-doped modified bagasse carbon material). (4) Take 1.2 g of ferric chloride hexahydrate and 1.6 g of potassium ferrocyanide trihydrate and add them to 200 mL of ultrapure water. Mix and stir at 45 °C for 15 min to obtain Prussian blue prenucleation solution; (5) Take 0.8 g of Mn@PSB prepared in step (3) and add it to 300 mL of ultrapure water, then add the Prussian blue prenucleation solution prepared in step (4). The volume of the resulting mixed solution is 500 mL. Stir the mixed solution for 3 h, centrifuge to obtain the precipitate, and wash the precipitate three times with deionized water and anhydrous ethanol respectively to obtain Mn@PSB / PB (manganese-doped Prussian blue composite modified bagasse carbon-based material).

[0035] 0.8 g each of Cu@PSB / PB prepared in Example 1, Cu@PBP / PB prepared in Example 2, Cu@PCS / PB prepared in Example 3, PSB / PB prepared in Comparative Example 1, Cu@PSB prepared in Comparative Example 2, and Mn@PSB / PB prepared in Comparative Example 3 were weighed and placed in quartz adsorption tubes. Ammonia adsorption performance was tested at an ammonia flow rate of 500 mL / min and a concentration of 500 ppm. The ammonia outlet concentration was measured using an ammonia infrared analyzer to determine the ammonia adsorption capacity of each composite material.

[0036] Figure 1 The N2 adsorption-desorption isotherms and pore size distribution diagrams for Cu@PSB / PB prepared in Example 1 are shown below. Figure 1 The N2 adsorption-desorption isotherms of Cu@PSB / PB exhibit typical Type IV characteristics, accompanied by an H4 hysteresis loop. The adsorption capacity increases rapidly in the low-pressure region, indicating that the material possesses both abundant micropores and a well-developed mesoporous structure, with capillary condensation occurring within the pores. The specific surface area of ​​this material is 483.24 m². 2 / g, total pore volume is 0.49 cm³. 3 The / g value indicates a high specific surface area and a well-developed pore structure. Prussian blue itself possesses a unique face-centered cubic open framework structure, whose abundant coordination channels and cage-like structures effectively increase the mesopore volume of the composite material, thus forming a hierarchical porous structure. This structure facilitates the full exposure of active sites and promotes the diffusion and mass transfer of ammonia molecules within the channels, thereby enhancing the ammonia adsorption performance of the material.

[0037] Figure 2 The XRD pattern of Cu@PSB / PB prepared in Example 1 is shown below. Figure 2 It can be seen that Cu@PSB / PB still mainly has an amorphous carbon structure. The four obvious characteristic diffraction peaks at 2θ = 17.5, 24.8, 35.4 and 39.8° are attributed to the (200), (220), (400) and (420) crystal planes of Prussian blue, respectively. The results show that the composite material of Prussian blue and Cu@PSB was successfully prepared by in-situ deposition. After the composite of Prussian blue and Cu@PSB, its face-centered cubic (FCC) crystal structure was not destroyed.

[0038] Figure 3 The infrared spectrum of Cu@PSB / PB prepared in Example 1 is shown below. Figure 3 It can be seen that Cu@PSB / PB has abundant functional groups, and at 2083 cm⁻¹ -1 The strong peak at that location belongs to the characteristic peak of PB and is Fe. 2+ -C≡N-Fe 3+ C≡N stretching vibrations in the element, located at 598 and 500 cm⁻¹. -1 The two moderately intense peaks are attributed to the stretching vibrations of Fe-C and Fe-N, respectively, further confirming the successful composite of Prussian blue with Cu@PSB.

[0039] Figure 7 The infrared spectrum of PSB / PB prepared in Comparative Example 1 is shown below, compared with the infrared spectrum of Cu@PSB / PB prepared in Example 1. Figure 3 The comparison shows that -OH and COO in Cu@PSB / PB - The enhanced intensity and sharper peak shape of the characteristic peaks indicate that the introduction of Cu promoted the uniform dispersion of PB on the carrier surface and increased the oxygen-containing functional group content of the composite material.

[0040] Figure 4 This is an adsorption breakthrough time curve of Cu@PSB / PB prepared in Example 1. Figure 6 The adsorption breakthrough time curve is shown for PSB / PB prepared in Comparative Example 1. Figure 8 The adsorption breakthrough time curve is shown for Cu@PSB prepared in Comparative Example 2. Figure 9 The adsorption breakthrough time curve of Mn@PSB / PB prepared for Comparative Example 3; Figure 12 The graph shows a comparison of the ammonia saturation adsorption capacity of the biochar materials prepared in Example 1, Comparative Example 3, Comparative Example 1 and Comparative Example 2.

[0041] from Figure 4 As can be seen, Cu@PSB / PB exhibits good ammonia capture ability and stability, with a breakthrough adsorption time of 197 min. The NH3 outlet concentration was detected using an ammonia infrared analyzer, and the calculated saturated ammonia adsorption capacity of Cu@PSB / PB was 62.34 mg / g. Its cyclic regeneration performance is as follows: Figure 5 As shown, Cu@PSB / PB retained 69.8% of its initial adsorption capacity after 5 cycles under desorption conditions at 200 °C, exhibiting good cycle stability and regeneration potential. Furthermore, compared to Cu@PSB materials without Prussian blue (e.g., ...), ... Figure 8 As shown), its adsorption performance is significantly improved, indicating that the composite Prussian blue can significantly enhance the material's ability to capture NH3. Meanwhile, compared with the unloaded Cu material in Comparative Example 1, which only composited Prussian blue with PSB / PB material (as shown), its adsorption performance is significantly improved. Figure 6As shown in the figure, the preloading of metal Cu not only promotes the stable anchoring of Prussian blue on the biochar matrix, but also the coexistence of the two components does not cause competition or inhibition between active sites. On the contrary, metal Cu and PB exhibit excellent functional complementarity during the adsorption process, which together maximizes the ammonia adsorption capacity of the material.

[0042] Figure 10 The adsorption breakthrough time curve of Cu@PBP / PB prepared in Example 2 is shown. The NH3 outlet concentration was detected using an ammonia infrared analyzer, and the calculated saturated adsorption capacity of Cu@PBP / PB was 58.13 mg / g. Figure 9 It can be seen that the breakthrough adsorption time of Cu@PBP / PB is 99 min, which is lower than the ammonia adsorption performance of Cu@PSB / PB in Example 1. This is attributed to the fact that, compared with bamboo powder, the modified biochar prepared by co-pyrolysis of sugarcane bagasse and phytic acid usually has a richer microporous structure and a larger specific surface area, which can provide more anchoring sites for Cu and Prussian blue, making the active components more uniformly dispersed, more stable in loading, and exposing more effective adsorption sites, thereby improving the ammonia adsorption capacity and prolonging the breakthrough time.

[0043] Figure 11 The adsorption breakthrough time curve of Cu@PCS / PB prepared in Example 3 is shown. The NH3 outlet concentration was detected using an ammonia infrared analyzer, and the calculated saturated adsorption capacity of Cu@PCS / PB was 50.57 mg / g. Figure 11 It can be seen that its breakthrough adsorption time is 148 min, and its adsorption performance is also lower than that of modified sugarcane bagasse carbon-based material. The reduction in performance may be due to the low degree of pore development and specific surface area of ​​the modified biochar prepared from camellia fruit shell, which makes it difficult to provide sufficient efficient adsorption sites and anchoring space for active components, thereby reducing its adsorption performance.

[0044] like Figure 6 As shown, the breakthrough adsorption time of the PSB / PB prepared in Comparative Example 1 was 34 min. The NH3 outlet concentration was detected using an ammonia infrared analyzer, and the calculated saturated adsorption capacity was 32.08 mg / g, significantly lower than that of the Cu-modified composite material. This indicates that the adsorption performance of PB combined with modified biochar alone is relatively limited, the number of active sites on the material surface is small, and the dispersion and binding stability of PB on the biochar matrix surface are weak, making it difficult to form an efficient synergistic adsorption interface. In contrast, the Cu loading not only provides additional active centers but also promotes the uniform dispersion of PB and its interfacial interaction with the support surface, thereby effectively improving the ammonia adsorption performance.

[0045] like Figure 8As shown in the figure, the ammonia breakthrough adsorption curve of Cu@PSB prepared in Comparative Example 2 indicates that the breakthrough adsorption time of Cu@PSB is 72 min and the saturated adsorption capacity of ammonia is 32.72 mg / g, indicating that the copper loading has a high adsorption capacity for ammonia, which is mainly attributed to Cu 2+ As a Lewis acid center, it can coordinate with the lone pair electrons of NH3 molecules, thereby enhancing the material's chemisorption capacity for ammonia. Simultaneously, the introduction of Cu can modulate the electronic structure and local chemical environment of the biochar surface, promoting the formation of more active sites and improving ammonia utilization efficiency. However, due to the lack of Prussian blue composite material, the types of active sites on the material surface remain relatively limited, and the synergistic effect of hierarchical pore structure and multifunctional sites is lacking; therefore, the overall adsorption capacity remains relatively limited.

[0046] The ammonia breakthrough adsorption curve of Mn@SB / PB prepared in Comparative Example 3 (e.g.) Figure 9 As shown in the figure, the breakthrough adsorption time of Mn@SB / PB is 148 min, and the saturated adsorption capacity of ammonia is 45.13 mg / g. This indicates that the preparation method and biomass char matrix material of the present invention still have a certain ammonia adsorption capacity after changing different metal components. However, compared with Cu@PSB / PB, the adsorption performance of Mn@PSB / PB is reduced, indicating that Cu may have a stronger coordination effect with ammonia than Mn. In addition, the dispersion state of Cu on the surface of biomass char matrix may be better than that of Mn, which is conducive to exposing more effective active sites and further enhancing the chemical adsorption capacity of the material.

[0047] This invention constructs a highly efficient ammonia adsorbent material with both hierarchical porous structure and multifunctional active sites by synergistically introducing metallic Cu and Prussian blue onto the surfaces of biochar matrices modified with different phytic acid. Experimental results show that the type of biochar matrix significantly affects the ammonia adsorption performance of the material. Cu@PSB / PB, prepared using modified bagasse char derived from bagasse waste biomass as the matrix, exhibits the best performance, with a saturated ammonia adsorption capacity of 62.34 mg / g and a breakthrough time of 197 min. The adsorption performance of materials using bamboo powder and camellia oleifera fruit shells as carbon matrices decreases sequentially. This may be mainly attributed to the differences in specific surface area and pore structure formed after phytic acid modification of different biomass precursors. Higher specific surface area and more developed micro / mesoporous structures generally provide more adsorption sites and loading space for active components, thereby promoting improved adsorption performance. Furthermore, while single-component modified biochar-based materials (PSB / PB or Cu@PSB) possess a certain ammonia adsorption capacity, their overall performance is limited. In contrast, the adsorption performance of the Cu@PSB / PB composite material is significantly improved. The above results indicate that the synergistic effect of Cu and PB can effectively increase the number of active sites on the surface of modified biochar materials, enhance Lewis acidity, and promote coordination between them and ammonia, thereby significantly improving their adsorption performance.

[0048] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing modified biomass carbon-based materials based on copper-supported / Prussian blue composites, characterized in that, The process includes the following steps: co-pyrolyzing phytic acid with a biomass precursor to obtain a high specific surface area biomass carbon matrix material; modifying the biomass carbon matrix material with a copper source and then calcining it to obtain a copper-loaded modified biomass carbon material; adding the copper-loaded modified biomass carbon material and a Prussian blue pre-nucleation solution to water, stirring, centrifuging to separate the precipitate, and washing to obtain the modified biomass carbon matrix material based on the copper-loaded / Prussian blue composite.

2. The preparation method of the modified biomass carbon-based material based on copper-supported / Prussian blue composite according to claim 1, characterized in that, The ratio of copper-loaded modified biochar material, Prussian blue prenuclearization solution, and water is 0.8 g: 200 mL: 300 mL.

3. The method for preparing modified biomass carbon-based materials based on copper-supported / Prussian blue composites according to claim 1, characterized in that, The biomass precursor is selected from sugarcane bagasse, bamboo powder or camellia fruit shell; The copper source is anhydrous copper chloride.

4. The method for preparing modified biomass carbon-based materials based on copper-supported / Prussian blue composite according to claim 1, characterized in that, The mass ratio of the biochar matrix material to the copper source is 1:0.423; The co-pyrolysis temperature was 600 °C and the time was 2 h. The copper source load modification time is 12 hours; The specific operation of the calcination is as follows: under an inert gas atmosphere, the temperature is increased at a rate of 5 °C / min, and the pyrolysis is carried out at a constant temperature of 350 °C for 2 h.

5. The method for preparing modified biomass carbon-based materials based on copper-supported / Prussian blue composites according to claim 1, characterized in that, The Prussian blue prenucleation solution is a mixed aqueous solution of ferric chloride hexahydrate and potassium ferrocyanide trihydrate.

6. The method for preparing modified biomass carbon-based materials based on copper-supported / Prussian blue composites according to claim 5, characterized in that, The ratio of ferric chloride hexahydrate, potassium ferrocyanide trihydrate, and water is 1.2 g: 1.6 g: 200 mL.

7. A modified biomass-based carbon material based on copper-supported / Prussian blue composite, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of the modified biomass carbon-based material based on copper-supported / Prussian blue composite as described in claim 7 in ammonia treatment.

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