A rare earth metal loaded bagasse biomass charcoal ammonia adsorbent, a preparation method and application thereof

Abstract

The application provides a rare earth metal loaded bagasse biomass charcoal ammonia adsorbent and a preparation method and application thereof, and belongs to the technical field of environmental functional materials.The application uses bagasse as a carbon matrix material, and modifies the material by phytic acid activation and rare earth metal salt loading to obtain a porous biomass charcoal material with uniform dispersion of rare earth metals.The introduction of the rare earth elements effectively controls the pore structure and surface electronic structure of the biomass charcoal, increases Lewis acid sites and coordination active centers, and enhances the chemical adsorption capacity of the biomass charcoal on ammonia molecules.The obtained adsorbent has a large specific surface area and rich surface functional groups, realizes the synergistic effect of physical adsorption and chemical adsorption, and significantly improves the ammonia adsorption capacity.The application has simple preparation process, low cost, and wide raw material sources, has good cycle stability and industrial application prospect, and can be used for ammonia purification in the fields of livestock and poultry breeding, sewage treatment and industrial waste gas treatment.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, and in particular relates to a rare earth metal supported bagasse biomass carbon-ammonia adsorbent, its preparation method and application. Background Technology

[0002] With the continuous expansion of livestock and poultry farming, wastewater treatment, and chemical production, ammonia (NH3) emissions have become an increasingly prominent problem. Ammonia not only has a strong, pungent odor, but it also easily forms secondary particulate matter (PM2.5). 2.5 High ammonia concentrations pose a serious threat to the ecological environment and human health. In enclosed or semi-enclosed environments (such as livestock sheds, landfills, and sewage treatment plants), excessively high ammonia concentrations can also affect production efficiency and operational safety. Therefore, developing efficient, low-cost, and environmentally friendly ammonia adsorption materials is of significant practical importance.

[0003] Currently, ammonia treatment technologies mainly include acid washing absorption, catalytic oxidation, biological treatment, and adsorption. Among these, adsorption has attracted widespread attention due to its simple operation, low energy consumption, and strong recyclability. Common adsorption materials include activated carbon, zeolites, molecular sieves, and metal oxides. However, traditional activated carbon mainly relies on physical adsorption, and its selectivity and adsorption capacity for polar ammonia molecules are limited. While zeolites and molecular sieves have certain selectivity, their preparation costs are high, and their adsorption performance is easily affected in high humidity environments. Therefore, developing novel ammonia adsorption materials with abundant active sites, tunable structures, and low costs has become a research hotspot.

[0004] Biochar, a porous carbon material obtained by pyrolysis of biomass under oxygen-limited or inert atmospheres, possesses advantages such as large specific surface area, tunable pore structure, abundant surface functional groups, and wide availability. Agricultural waste, represented by bagasse, is abundant and inexpensive, making it an ideal precursor for biochar production. However, unmodified biochar has limited ammonia adsorption capacity, with its adsorption mechanism primarily based on physical adsorption and insufficient chemical adsorption sites, thus restricting its application in the field of efficient ammonia removal.

[0005] In recent years, modifying biochar with metals or metal oxides to enhance its surface acidic sites and coordination adsorption capacity has become an important research direction. Rare earth metals, in particular, possess unique 4f electronic structures, exhibiting strong Lewis acidity and coordination capabilities. They can form stable coordination bonds or acid-base interactions with ammonia molecules, thus significantly improving the chemisorption performance of the material. Simultaneously, rare earth element loading may also regulate the pore structure and surface electronic structure of biochar, promoting multi-mechanism synergistic adsorption. However, current research on rare earth metal-loaded modified biochar for ammonia adsorption remains limited, and problems such as poor loading uniformity, low utilization of active sites, and complex preparation processes exist. Therefore, there is an urgent need to develop a method for preparing rare earth metal-loaded bagasse biochar ammonia adsorbents with controllable structure, abundant active sites, simple preparation process, and suitability for large-scale production, in order to improve the adsorption capacity and selectivity of ammonia and expand the pathways for high-value utilization of agricultural waste. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention proposes a method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, comprising the following steps: (1) Phytic acid and bagasse powder (SB) are mixed, deionized water is added and stirred, and dried to obtain phytic acid-bagasse mixture; (2) The phytic acid-bagasse mixture was subjected to programmed temperature pyrolysis under a nitrogen atmosphere, and after washing and drying, phytic acid activated bagasse biochar (PSB) was obtained. (3) The phytic acid activated bagasse biochar was loaded with rare earth metal salts by an equal volume impregnation method and dried to obtain a rare earth metal loaded bagasse biochar precursor. (4) The rare earth metal-supported bagasse biochar precursor is calcined under a nitrogen atmosphere to obtain the rare earth metal-supported bagasse biochar ammonia adsorbent (M@PSB, where M is a rare earth metal).

[0008] Further, in step (1), the mass ratio of phytic acid to bagasse powder is (1~3):(1~3), preferably 1:1 or 2:1.

[0009] Further, in step (2), the pyrolysis temperature of the programmed temperature pyrolysis is 400~800℃, and the reaction is carried out at a constant temperature for 1~5h under nitrogen protection. The heating rate of the programmed temperature pyrolysis is 5℃ / min.

[0010] Furthermore, in step (3), the rare earth metal salt is cerium chloride heptahydrate and / or lanthanum chloride heptahydrate.

[0011] Further, in step (3), the metal element in the rare earth metal salt accounts for 2-20% of the mass fraction of the phytic acid activated bagasse biochar, preferably 5%-20%.

[0012] Furthermore, in step (3), the equal-volume impregnation method is carried out under ultrasonic conditions, with an impregnation temperature of 35°C and an impregnation time of 12 hours.

[0013] Furthermore, in step (4), the calcination temperature is 300~600℃ and the calcination time is 1~4h.

[0014] More specifically, the preparation method of the rare earth metal supported bagasse biomass carbon-ammonia adsorbent of the present invention includes the following steps: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of (1~3): (1~3), add deionized water and mix for 8~20h, then dry in an oven at 80~150℃ for 10~24h. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature is increased at a rate of 5℃ / min, the pyrolysis temperature is set to 400~800℃, and the reaction is kept at a constant temperature for 1~5h; (4) After the reaction is complete, cool to room temperature, take out the sample and wash it with deionized water until neutral, and dry the washed material in an oven at 80~150℃ for 10~24h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and rare earth metal with a mass fraction of 2~20% of metal elements, use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in an oven at 80~150℃ to dry for 10~24h. (6) Transfer the material obtained in step (5) into a quartz boat and calcine it under a nitrogen atmosphere for 1-4 hours at a pyrolysis temperature of 300-600℃ to obtain rare earth metal-supported bagasse biomass carbon-ammonia adsorbent (M). X @PSB Y Where X represents the metal loading ratio and Y represents the mass ratio of phytic acid to bagasse powder.

[0015] The present invention also proposes a rare earth metal supported bagasse biomass carbon-ammonia adsorbent, which is prepared by the above preparation method.

[0016] The rare earth metal-supported bagasse biomass carbon ammonia adsorbent obtained by this invention has the characteristics of large specific surface area, uniform loading of rare earth metals, abundant active sites, and high sample synthesis yield.

[0017] The present invention also proposes an application of the above-mentioned rare earth metal supported bagasse biomass carbon ammonia adsorbent in the removal of gaseous ammonia.

[0018] This invention utilizes bagasse as a carbon source and employs a two-step heat treatment process combining phytic acid activation and equal-volume impregnation of rare earth metals to construct a structurally tunable rare earth metal-supported porous biochar system. Through synergistic activation with phytic acid in the initial stage, pore structure formation and phosphorus-containing functional groups are promoted during pyrolysis, providing abundant anchoring sites for subsequent rare earth metal loading. Simultaneously, a programmed temperature rise pyrolysis process under vacuum and nitrogen protection effectively avoids oxidation side reactions and improves the structural stability of the material. The equal-volume impregnation combined with secondary calcination method facilitates the uniform dispersion and stable loading of rare earth metals on the surface of the bagasse biochar, preventing agglomeration. The overall preparation process is controllable, reproducible, and suitable for large-scale production, combining the dual advantages of agricultural waste resource utilization and high-value-added functional material preparation.

[0019] Compared with the prior art, the present invention has the following advantages and technical effects: The rare earth metal-supported bagasse biomass carbon-ammonia adsorbent (M) prepared by this invention X @PSB Y This material possesses a large specific surface area and a well-developed pore structure, with uniformly distributed rare-earth active sites and phosphorus-containing functional groups on its surface, enabling synergistic enhancement of physical and chemical adsorption. The introduction of rare-earth metals significantly increases the number of Lewis acid sites in the material, enhancing its coordination adsorption capacity for ammonia molecules. It exhibits excellent adsorption performance and stability under ammonia concentrations of 500 ppm and flow rates of 500 mL / min. Furthermore, the material of this invention boasts high synthesis yield, a simple preparation method, uniform metal loading, stable structure, and suitability for large-scale scaling, demonstrating good potential for recycling and industrial application. Attached Figure Description

[0020] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 The N2 adsorption-desorption isotherm and pore size distribution of Ce5@PSB1 prepared in Example 1; Figure 2 The image shows the XRD pattern of Ce5@PSB1 in Example 1; Figure 3This is the adsorption breakthrough time curve of Ce5@PSB1 in Example 1; Figure 4 The diagram shows the cyclic stability of Ce5@PSB1 in Example 1; Figure 5 This is the adsorption breakthrough time curve of Ce5@PSB2 in Example 2; Figure 6 Ce in Example 3 20 Adsorption-breakthrough time curve of @PSB1; Figure 7 This is the adsorption-breakthrough time curve of La5@PSB1 in Example 4; Figure 8 The adsorption-breakthrough time curve of PSB in Comparative Example 1 is shown. Figure 9 This is the adsorption breakthrough time curve of Ni5@PSB1 in Comparative Example 2; Figure 10 This is a graph showing the adsorption breakthrough time of Ce@SB in Comparative Example 3. Figure 11 For PSB, Ce@SB, Ce5@PSB1, Ce5@PSB2, Ce 20 Results of saturated adsorption capacity determination for @PSB1, La5@PSB1, and Ni5@PSB1. 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] This invention provides a method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, comprising the following steps: (1) Mix phytic acid with bagasse powder, add deionized water and stir, and dry to obtain a phytic acid-bagasse mixture; (2) The phytic acid-bagasse mixture was subjected to programmed temperature pyrolysis under a nitrogen atmosphere, and after washing and drying, phytic acid activated bagasse biochar (PSB) was obtained. (3) Phytic acid activated bagasse biochar and rare earth metal salts were loaded by equal volume impregnation and dried to obtain rare earth metal loaded bagasse biochar precursor. (4) The rare earth metal-supported biochar precursor was calcined under a nitrogen atmosphere to obtain a rare earth metal-supported bagasse biochar ammonia adsorbent (M). X @PSB Y Where X represents the metal loading ratio and Y represents the mass ratio of phytic acid to bagasse powder.

[0027] In the preparation method of this invention, the phytic acid used contains polyphosphate groups, which act as an activator and uniformly composite with the carbon source precursor, laying the foundation for subsequent pyrolysis pore formation and the introduction of phosphorus-containing functional groups. Vacuum programmed temperature pyrolysis can eliminate air and avoid oxidation, and the programmed temperature can controllably form a porous carbon framework, simultaneously introducing phosphoric acid sites and improving the surface activity of biochar. Equal volume impregnation loading ensures that rare earth metal salts uniformly enter the biochar channels, avoiding agglomeration and achieving precise dispersion of metal sites. Subsequently, an inert atmosphere prevents metal oxidation, allowing the rare earth metals to be anchored in a stable valence state on the biochar surface, forming highly efficient ammonia adsorption active centers. The porous structure provides physical adsorption sites, while the rare earth metals and phosphorus-containing groups provide chemical adsorption sites, and the dual mechanism enhances ammonia adsorption performance.

[0028] In some preferred embodiments of the present invention, the mass ratio of phytic acid to bagasse powder is (1~3):(1~3); for example, it can be 1:1 or 2:1. If the ratio of phytic acid to bagasse powder is too low, there will be insufficient phytic acid, resulting in inadequate activation and pore formation, smaller specific surface area and pore volume, and weak physical adsorption capacity. If the ratio is too high, there will be excessive phytic acid, leading to excessive etching that causes the carbon skeleton to collapse, destroys the pore structure, and increases costs and the difficulty of subsequent washing.

[0029] In some preferred embodiments of the present invention, deionized water is added and mixed and stirred for 8-20 hours, and then dried in an oven at 80-150°C for 10-24 hours; for example, deionized water is added and mixed and stirred for 12 hours, and then dried in an oven at 105°C for 12 hours.

[0030] In some preferred embodiments of the present invention, the pyrolysis temperature of the programmed temperature pyrolysis is 400~800℃, and the reaction is carried out at a constant temperature for 1~5 hours under nitrogen protection. The heating rate of the programmed temperature pyrolysis is 5℃ / min. For example, the pyrolysis temperature of the programmed temperature pyrolysis is 600℃, and the reaction is carried out at a constant temperature for 2 hours under nitrogen protection.

[0031] In some preferred embodiments of the present invention, PSB is obtained by drying in an oven at 80~150℃ for 10~24h after programmed temperature pyrolysis; for example, it is dried in an oven at 105℃ for 12h.

[0032] In some preferred embodiments of the present invention, the rare earth metal salts are cerium chloride heptahydrate and / or lanthanum chloride heptahydrate. Ce and La have unique 4f electron structures and strong Lewis acidity, which can form stable coordination bonds with NH3, enhancing chemisorption. Furthermore, the chloride salts have good soluble properties and are easily and uniformly dispersed during equal-volume impregnation; the heptahydrates have moderate water of crystallization, making the impregnation process easy to control and preventing the introduction of impurities. Compared to non-rare earth metals (such as Ni), the coordination centers formed by Ce and La are more stable, resulting in higher ammonia adsorption capacity and selectivity.

[0033] In some preferred embodiments of the present invention, the metal element in the rare earth metal salt accounts for 2 to 20% of the mass fraction of phytic acid activated bagasse biochar; for example, the mass fraction is 5% and 20%.

[0034] In some preferred embodiments of the present invention, the equal-volume impregnation method is carried out under ultrasonic conditions, the impregnation temperature is 35°C, and the impregnation time is 12h.

[0035] In some preferred embodiments of the present invention, the calcination temperature is 300~600℃ and the calcination time is 1~4h; for example, the calcination temperature is 350℃ and the calcination time is 2h.

[0036] This invention also proposes a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, which is prepared by the above-described method.

[0037] The rare earth metal-supported bagasse biomass carbon ammonia adsorbent prepared in the embodiments of the present invention can be used to remove gaseous ammonia.

[0038] This invention utilizes a porous structure of rare earth metal-supported bagasse biomass carbon ammonia adsorbent to physically capture NH3 molecules. The acidic sites of the rare earth elements coordinate with the (alkaline) NH3, achieving efficient and stable adsorption. It can be used for the purification of low-concentration gaseous ammonia in livestock and poultry farming, sewage treatment, and industrial waste gas. The material is stable and recyclable, low in cost, and the raw materials are readily available, making it suitable for industrial-scale production.

[0039] All raw materials used in the embodiments of this invention were purchased commercially.

[0040] The technical solution of the present invention will be further illustrated by the following embodiments.

[0041] Example 1 A method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent includes the following steps: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 1:1, add deionized water and mix for 12 hours. After mixing, place in an oven at 105℃ and dry for 12 hours. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and cerium chloride heptahydrate (the metal element accounts for 5% of the mass fraction of PSB), use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in an oven at 105℃ to dry for 12h. (6) The material obtained in step (5) is transferred to a quartz boat and calcined for 2 hours under a nitrogen atmosphere. The pyrolysis temperature is 350℃ to obtain rare earth metal supported bagasse biomass carbon ammonia adsorbent (Ce5@PSB1).

[0042] Example 2 A method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent includes the following steps: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 2:1, add deionized water and mix for 12 hours. After mixing, place in an oven at 105℃ and dry for 12 hours. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and cerium chloride heptahydrate (the metal element accounts for 5% of the mass fraction of PSB), use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in an oven at 105℃ to dry for 12h. (6) The material obtained in step (5) is transferred to a quartz boat and calcined for 2 hours under a nitrogen atmosphere. The pyrolysis temperature is 350℃ to obtain rare earth metal supported bagasse biomass carbon ammonia adsorbent (Ce5@PSB2).

[0043] Example 3 A method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent includes the following steps: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 1:1, add deionized water and mix for 12 h, then dry in an oven at 105℃ for 12 h. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and cerium chloride heptahydrate (the metal element accounts for 20% of the mass fraction of PSB), use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in an oven at 105℃ to dry for 12h. (6) The material obtained in step (5) is transferred to a quartz boat and calcined under a nitrogen atmosphere for 2 hours at a pyrolysis temperature of 350℃ to obtain rare earth metal-supported bagasse biomass carbon-ammonia adsorbent (Ce). 20 @PSB1).

[0044] Example 4 A method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent includes the following steps: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 1:1, add deionized water and mix for 12 hours. After mixing, place in an oven at 105℃ and dry for 12 hours. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and lanthanum chloride heptahydrate (the metal element accounts for 5% of the mass fraction of PSB), use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in a 90℃ oven to dry for 12h. (6) The material obtained in step (5) is transferred to a quartz boat and calcined for 2 hours under a nitrogen atmosphere. The pyrolysis temperature is 350℃ to obtain rare earth metal supported bagasse biomass carbon ammonia adsorbent (La5@PSB1).

[0045] Comparative Example 1 Same as Example 1, except that the addition of cerium chloride heptahydrate is omitted, specifically: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 1:1, add deionized water and mix for 12 hours. After mixing, place in an oven at 105℃ and dry for 12 hours. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is complete, cool to room temperature, take out the sample and wash it with deionized water until neutral, and dry the washed material in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB).

[0046] Comparative Example 2 Same as Example 1, except that the rare earth metal (cerium chloride heptahydrate) is replaced with a non-rare earth metal (anhydrous nickel chloride), specifically: (1) Weigh phytic acid and sugarcane bagasse powder at a mass ratio of 1:1, add deionized water and mix for 12 hours. After mixing, place in an oven at 105℃ and dry for 12 hours. (2) Transfer the above mixture to a quartz boat, place it in the center of the quartz tube of the tube furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (3) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 hours. (4) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain phytic acid activated bagasse biochar (PSB). (5) Take 1.0g of PSB and anhydrous nickel chloride (the metal element accounts for 5% of the mass fraction of PSB), use the equal volume impregnation method, sonicate at 35℃ for 1h, impregnate for 12h, and then place in an oven at 105℃ to dry for 12h. (6) The material obtained in step (5) is transferred to a quartz boat and calcined for 2 hours under a nitrogen atmosphere. The pyrolysis temperature is 350℃ to obtain a non-rare earth metal supported bagasse biomass carbon ammonia adsorbent (Ni5@PSB1).

[0047] Comparative Example 3 Same as Example 1, except that the phytic acid activation treatment in step (1) is omitted, and the unactivated bagasse biochar is directly mixed with rare earth metals for modification, specifically: (1) Transfer the bagasse powder to a quartz boat, place it in the center of the quartz tube of the tubular furnace, seal it well, and then perform vacuuming three times to ensure that all air is removed. (2) Under nitrogen protection, the temperature was increased at a rate of 5℃ / min, the pyrolysis temperature was set to 600℃, and the reaction was kept at a constant temperature for 2 h. (3) After the reaction is completed, the sample is cooled to room temperature, taken out and washed with deionized water until neutral, and the washed material is dried in an oven at 105℃ for 12h to obtain bagasse biochar (SB). (4) Take 1.0g of sugarcane bagasse biochar and cerium chloride heptahydrate (the metal element accounts for 5% of the mass fraction of SB), use the equal volume impregnation method, sonicate at 35℃ for 1 h, impregnate for 12 h, and then place in an oven at 105℃ to dry for 12 h. (5) The material obtained in step (4) is transferred to a quartz boat and calcined in a nitrogen atmosphere for 2 hours at a pyrolysis temperature of 350°C to obtain rare earth metal supported bagasse biomass carbon ammonia adsorbent (Ce@SB).

[0048] Performance testing The adsorbents prepared in Examples 1-4 and Comparative Examples 1-3 were placed in quartz adsorption tubes, and their ammonia adsorption performance was tested at an ammonia flow rate of 500 mL / min and a concentration of 500 ppm.

[0049] Figure 1 The N2 adsorption-desorption isotherm and pore size distribution of Ce5@PSB1 prepared in Example 1 are shown below. Figure 1The N2 adsorption-desorption curves of Ce5@PSB1 show typical type I isotherms, indicating a rich microporous structure. The pore size distribution further confirms the uniform pore size distribution of Ce5@PSB1, mainly concentrated in micropores and narrow mesopores below 10 nm, with the most accessible pore size being 1.6 nm, indicating that the material is predominantly microporous. The specific surface area of ​​this material is 763.22 m². 2 / g, total pore volume is 0.42cm³ 3 / g, with a micropore volume of 0.24cm³. 3 / g, the high specific surface area and abundant micropores provide more active sites for ammonia adsorption. XRD analysis shows that Ce5@PSB1 has an amorphous structure. The XRD pattern does not show sharp characteristic peaks for Ce, indicating that the introduction of Ce did not significantly alter the carbon skeleton structure of bagasse biochar. Metallic Ce is mainly highly dispersed in PSB in an amorphous form, or uniformly distributed within the microporous structure of PSB, which is beneficial for the full exposure of active sites (see...). Figure 2 ).

[0050] Figure 3 This is the adsorption breakthrough time curve of Ce5@PSB1 in Example 1; Figure 4 The diagram shows the cyclic stability of Ce5@PSB1 in Example 1; Figure 5 This is the adsorption breakthrough time curve of Ce5@PSB2 in Example 2; Figure 6 Ce in Example 3 20 Adsorption-breakthrough time curve of @PSB1; Figure 7 This is the adsorption-breakthrough time curve of La5@PSB1 in Example 4; Figure 8 The adsorption-breakthrough time curve of PSB in Comparative Example 1 is shown. Figure 9 This is the adsorption breakthrough time curve of Ni5@PSB1 in Comparative Example 2; Figure 10 This is a graph showing the adsorption breakthrough time of Ce@SB in Comparative Example 3. Figure 11 In the examples and comparative examples, PSB, Ce@SB, Ce5@PSB1, Ce5@PSB2, and Ce 20 Results of saturated adsorption capacity determination for @PSB1, La5@PSB1, and Ni5@PSB1.

[0051] It can be seen that Ce5@PSB1 exhibits a high ammonia adsorption capacity, with a saturation adsorption capacity of 22.98 mg / g and an adsorption breakthrough time of up to 72 min, indicating that the material has a long adsorption protection time. Figure 3 Compared with Comparative Example 1, the PSB prepared without Ce loading under the same activation ratio and reaction temperature conditions had an ammonia saturation adsorption capacity of only 10.13 mg / g, indicating that the introduction of Ce active sites significantly improved the NH3 capture capacity. Furthermore, the adsorption-regeneration cycle experiment results showed that... Figure 4 After regeneration at 200℃ with nitrogen purging at 200 mL / min for 2 h, the adsorption capacities of Ce5@PSB1 material in five consecutive adsorption cycles were 22.98, 18.51, 17.92, 16.84, and 15.62 mg / g, respectively, showing a gradual decreasing trend. However, after the fifth cycle, it still retained an adsorption capacity of 15.62 mg / g, which is 67.97% of the initial adsorption capacity. This indicates that the material still has good cycle stability and regeneration performance during multiple adsorption-regeneration processes. The above results show that phytic acid activation and metal Ce loading can effectively construct relatively stable surface active sites and pore structures, thereby enabling the material to maintain good ammonia adsorption capacity during cyclic use.

[0052] The adsorption breakthrough time of Ce5@PSB2 was 66 min, and the saturated adsorption capacity of ammonia was 20.80 mg / g. Figure 5 Compared to the Ce5@PSB1 material in Example 1, the adsorption performance of the material was reduced, indicating that an appropriate amount of phytic acid activation can effectively increase the acidic functional groups on the biochar surface and optimize the pore structure, resulting in a more rational distribution of micropores and mesopores, thereby enhancing the synergistic effect between the matrix biochar and the supported metal. Therefore, by controlling the phytic acid activation ratio, the pore structure and surface chemical properties of the material can be regulated, thereby optimizing the ammonia adsorption performance of the material.

[0053] Ce 20 The adsorption breakthrough time of @PSB1 was 53 min, and the saturated adsorption capacity of ammonia was 20.30 mg / g. Figure 6Compared to the Ce5@PSB1 material in Example 1, its adsorption performance was reduced, indicating that the Ce loading ratio has a significant impact on the material's adsorption performance. An appropriate Ce loading can increase the active sites on the material surface and enhance the synergistic effect between the phytic acid-activated biochar matrix and the metal components. When the Ce loading ratio is too high, excess rare earth metal components are prone to agglomeration and block some pores, disrupting the original optimal pore structure distribution, reducing the effective specific surface area and the number of available adsorption sites, thus leading to a decrease in ammonia adsorption performance. Therefore, by controlling the Ce loading ratio, the pore structure and surface chemical properties of the material can be regulated, thereby optimizing the ammonia adsorption performance of the material.

[0054] The La5@PSB1 adsorption breakthrough time was 69 min, and the saturated adsorption capacity of ammonia was 21.25 mg / g. Figure 7 The results showed good ammonia adsorption performance, indicating that the introduction of La element can achieve a synergistic enhancement effect by strengthening Lewis acid sites and surface coordination active centers. Combined with the test results of Example 1, it can be further demonstrated that rare earth metal loading can effectively improve the ammonia adsorption performance of biomass carbon-based materials by regulating the surface chemical properties of the material, increasing Lewis acid active sites, and coordinating with ammonia.

[0055] The PSB adsorption-penetration time was 33 min (see...). Figure 8 The saturated adsorption capacity for ammonia was 10.13 mg / g. The adsorption breakthrough time of Ni5@PSB1 was 53 min (see...). Figure 9 The ammonia saturation adsorption capacity was 16.05 mg / g, lower than that of Ce5@PSB1 in Example 1 and La5@PSB1 in Example 3. This further indicates that rare earth metals Ce and La are more conducive to forming Lewis acidic centers and coordination adsorption sites on the surface of biochar that are more effective in reacting with NH3, thus exhibiting higher ammonia adsorption performance. In addition, Ce@SB, obtained by directly mixing and modifying unactivated bagasse biochar with Ce, had an adsorption breakthrough time of 33 min (see...). Figure 10 The saturated adsorption capacity of ammonia was 9.43 mg / g, significantly lower than that of Ce5@PSB1. This further indicates that phytic acid activation not only improves the pore structure of the material and introduces oxygen-containing functional groups, increasing the acidic sites and effective adsorption sites on the material surface, but also provides more anchoring sites for rare earth metal loading, improving the dispersion and stability of the metal active components on the biochar surface, thereby enhancing the interaction between the rare earth metal active sites and the carbon matrix material. This demonstrates that phytic acid activation and rare earth metal loading have a synergistic enhancing effect; both can jointly improve the pore structure, surface functional groups, and uniform distribution of active sites in the biochar material, thus improving the adsorption performance of biochar for NH3.

[0056] The combined experimental results of Examples 1-4, Comparative Examples 1, 2, and 3 show that this invention successfully constructs a highly efficient ammonia adsorption material with both well-developed pore structure and surface chemically active sites by loading rare earth metals onto the surface of phytic acid-modified bagasse biochar. Experimental results indicate that the bagasse biochar material activated with phytic acid and loaded with rare earth metals exhibits strong adsorption performance for NH3. The Ce5@PSB1 material achieves a saturated adsorption capacity of 22.98 mg / g and an adsorption breakthrough time of 72 min, demonstrating the best ammonia adsorption effect. Compared to PSB without rare earth metal loading and the Ni-loaded comparative material, rare earth metals Ce and La are more conducive to forming Lewis acidic centers and coordination active sites on the material surface, which are more effective for NH3 adsorption, thus significantly improving the adsorption capacity and dynamic adsorption performance of the material. Furthermore, research shows that phytic acid activation not only improves the pore structure of the biochar, introduces oxygen-containing functional groups and acidic sites, but also provides more anchoring points for rare earth metal loading, improving the dispersion and stability of the metal active components on the carbon matrix surface. This demonstrates a significant synergistic effect between phytic acid activation and rare earth metal loading. Both factors work together to optimize the surface chemistry and pore structure of the bagasse carbon-based material, promoting a uniform distribution of active sites and thus significantly enhancing the material's NH3 adsorption performance. Furthermore, Ce5@PSB1 maintains a high adsorption capacity even after multiple adsorption-regeneration cycles, indicating that the material of this invention also possesses good cycle stability and recyclability, thus showing promising prospects for practical applications.

[0057] This invention addresses the limitations of existing biochar-based adsorbents in terms of limited ammonia adsorption capacity, insufficient selectivity, and low utilization of active sites. It proposes a method for preparing functionalized bagasse biochar based on rare-earth metal modification, achieving synergistic optimization of pore structure control and surface active site construction. This method not only fully utilizes bagasse, a widely available and inexpensive agricultural and forestry waste resource, improving its high-value utilization, but also significantly enhances the material's adsorption and removal capacity under low-concentration ammonia conditions through the synergistic effect of phytic acid modification and rare-earth metal loading. This provides a new technical pathway for developing high-performance, biochar-based ammonia adsorbents.

[0058] 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. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, characterized in that, Includes the following steps: (1) Mix phytic acid with bagasse powder, add deionized water and stir, and dry to obtain a phytic acid-bagasse mixture; (2) The phytic acid-bagasse mixture is subjected to programmed temperature pyrolysis under a nitrogen atmosphere, and after washing and drying, phytic acid activated bagasse biochar is obtained. (3) The phytic acid activated bagasse biochar was loaded with rare earth metal salts by an equal volume impregnation method and dried to obtain a rare earth metal loaded biochar precursor. (4) The rare earth metal supported biochar precursor is calcined under a nitrogen atmosphere to obtain the rare earth metal supported bagasse biochar ammonia adsorbent.

2. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (1), the mass ratio of phytic acid to bagasse powder is (1~3):(1~3).

3. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (2), the pyrolysis temperature of the programmed heating pyrolysis is 400~800℃, and the reaction is carried out at a constant temperature for 1~5 hours under nitrogen protection.

4. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 3, characterized in that, The heating rate of the programmed pyrolysis is 5℃ / min.

5. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (3), the rare earth metal salt is cerium chloride heptahydrate and / or lanthanum chloride heptahydrate.

6. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (3), the metal element in the rare earth metal salt accounts for 2-20% of the mass fraction of the phytic acid activated bagasse biochar.

7. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (3), the equal volume impregnation method is carried out under ultrasonic conditions, the impregnation temperature is 35℃, and the impregnation time is 12h.

8. The preparation method of the rare earth metal-supported bagasse biomass carbon-ammonia adsorbent according to claim 1, characterized in that, In step (4), the calcination temperature is 300~600℃ and the calcination time is 1~4h.

9. A rare earth metal-supported bagasse biomass carbon-ammonia adsorbent, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the rare earth metal supported bagasse biomass carbon ammonia adsorbent as described in claim 9 in the removal of gaseous ammonia.

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