Cobalt-loaded peanut shell biochar composite material as well as preparation method and application thereof
By preparing cobalt-supported peanut shell biochar composite materials, the problems of loading and stability of cobalt-based catalysts were solved, and the efficient activation of peracetic acid to degrade organic pollutants, especially sulfamethoxazole, was achieved, exhibiting high catalytic activity and stability.
Patent Information
- Application Number
- CN202610074033.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-28
- Publication Date
- 2026-02-24
AI Technical Summary
Existing cobalt-based catalysts suffer from contradictions between catalytic activity and loading, catalytic stability and loading, and limitations in the universality of supports and processes. It is difficult to achieve high cobalt loading, high dispersion of active sites, high reaction stability and low leaching rate, and it is impossible to efficiently activate peracetic acid to degrade organic pollutants.
By first preparing peanut shell biochar through pyrolysis, and then carrying out hydrothermal reaction and high-temperature pyrolysis, a cobalt-supported peanut shell biochar composite material was prepared. Using peanut shell biochar as a carrier, the cobalt species were stably loaded in a highly dispersed form through hydrothermal reaction and high-temperature pyrolysis, forming strong chemical bonds, thus achieving high loading and high catalytic activity.
It achieves high loading capacity, high catalytic activity, high reaction stability and low leaching rate, and can efficiently activate peracetic acid to degrade organic pollutants, especially antibiotics such as sulfamethoxazole, and has significant catalytic performance and structural stability.
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Figure CN121551004A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of functional materials technology, specifically to a cobalt-loaded peanut shell biochar composite material, its preparation method, and its application. Background Technology
[0002] With the acceleration of industrialization, various recalcitrant organic pollutants, such as antibiotics, dyes, and endocrine disruptors, are entering the aquatic environment, posing a serious threat to ecosystems and human health. Advanced oxidation processes have attracted much attention due to their ability to generate strong oxidizing free radicals, thereby efficiently degrading pollutants. Persulfate activation is one of the commonly used techniques, but it has limitations such as high oxidant costs and secondary pollution from some activation methods. In recent years, peroxide oxidants such as peracetic acid (PAA) have shown application potential due to their strong oxidizing power and environmentally friendly byproducts, but efficient and stable activation technologies for them still need to be developed.
[0003] Biochar, a porous carbon material obtained from biomass pyrolysis, is widely used as a catalyst support due to its abundant sources, low cost, environmental friendliness, and ease of functionalization. Transition metals (such as cobalt, iron, and copper) supported on biochar can effectively activate oxidants such as persulfate or hydrogen peroxide. Cobalt-based catalysts have attracted particular attention due to their excellent activation potential for various peroxides. However, the following prominent problems still exist in the existing technology: The trade-off between catalytic activity and loading capacity means that increasing the loading of active metal is often necessary to improve catalytic efficiency. However, conventional methods such as impregnation-pyrolysis can easily lead to the aggregation and uneven distribution of metal nanoparticles during the process of increasing cobalt loading, which can clog the support pores and mask active sites, resulting in a decrease in catalytic efficiency.
[0004] The contradiction between catalytic stability and loading: high loading is usually accompanied by a weakening of the interaction between the metal and the support, which makes the active components easy to leach out and lose during the catalytic process. This not only causes catalyst deactivation, but also causes secondary pollution of heavy metals, making it difficult to meet the stringent stability requirements of actual water treatment applications.
[0005] The universality of carriers and processes is limited. The performance of biochar carriers is highly dependent on the source of precursors and their own physicochemical properties, such as pore structure, surface functional groups, and ash composition. Most existing technologies focus on general processes and fail to design loading processes that match specific carriers, making it difficult to simultaneously achieve high dispersion and strong binding of metals with optimization of carrier structure.
[0006] Therefore, designing a preparation method that can simultaneously achieve high cobalt loading, high active site dispersion, high reaction stability, low leaching rate, high recycling stability, and match with a specific biochar support, thereby obtaining a composite material that can efficiently and stably activate oxidants such as peracetic acid, is a key technical problem that urgently needs to be solved in the field of water treatment catalytic materials. Summary of the Invention
[0007] To address the aforementioned technical problems, this application provides a cobalt-supported peanut shell biochar composite material, its preparation method, and its application. This application involves first preparing peanut shell biochar through a first pyrolysis, then using the peanut shell biochar as a carrier, and finally, through a hydrothermal reaction followed by a second high-temperature pyrolysis, ensuring that high-content cobalt species are stably loaded onto the peanut shell biochar in a highly dispersed form. The resulting cobalt-supported peanut shell biochar composite material achieves high loading capacity, high catalytic activity, high reaction stability, low leaching rate, and high recyclability stability, exhibiting significant advantages, particularly in activating peracetic acid to degrade organic pollutants.
[0008] In a first aspect, this application provides a method for preparing the cobalt-supported peanut shell biochar composite material, comprising the following steps: Peanut shell biochar was dispersed in an aqueous solution of CoCl2·6H2O and subjected to a hydrothermal reaction. After the reaction was completed, the product was dried to obtain a solid product. The solid product was then subjected to pyrolysis again in an inert atmosphere at a temperature of 750-850℃ to obtain the cobalt-supported peanut shell biochar composite material.
[0009] Furthermore, the mass ratio of peanut shell biochar to cobalt salt is 1:(1-5); preferably, the mass ratio of peanut shell biochar to cobalt salt is 1:(4-5).
[0010] Furthermore, the concentration of the CoCl2·6H2O aqueous solution is 0.03M-0.09M.
[0011] Furthermore, the hydrothermal reaction conditions include a reaction temperature of 65℃-75℃ and a reaction time of 3-5h; preferably, the hydrothermal reaction conditions are a reaction temperature of 70℃ and a reaction time of 4h.
[0012] Furthermore, the drying conditions include a drying temperature of 75℃-85℃ and a drying time of 10-14h; preferably, the drying conditions are a drying temperature of 80℃ and a drying time of 12h.
[0013] Furthermore, the temperature is increased to 750-850℃ at a heating rate of 4-6℃ / min, and the pyrolysis time is 2-4 hours; preferably, the pyrolysis conditions are to increase the temperature to 800℃ at a heating rate of 5℃ / min and pyrolyze for 3 hours.
[0014] Furthermore, the product after pyrolysis at elevated temperature is washed repeatedly with ethanol and ultrapure water until the washing liquid is neutral, and then dried to obtain the cobalt-supported peanut shell biochar composite material.
[0015] Furthermore, the preparation method of the peanut shell biochar includes: placing peanut shell powder in an inert atmosphere and heating it to pyrolyze to obtain peanut shell biochar powder; repeatedly washing the obtained peanut shell biochar powder with ultrapure water until neutral, and drying it to obtain the peanut shell biochar.
[0016] Furthermore, the peanut shell powder has a particle size of 180-220 mesh.
[0017] Furthermore, the pyrolysis conditions in the preparation method of peanut shell biochar include heating to 650-750℃ at a heating rate of 4-6℃ / min and pyrolysis for 1.5-3 hours.
[0018] Furthermore, the drying conditions in the preparation method of peanut shell biochar include a drying temperature of 75-85℃ and a drying time of 2-4h.
[0019] Secondly, this application provides a cobalt-loaded peanut shell biochar composite material, prepared by the method of the first aspect, wherein the cobalt-loaded peanut shell biochar composite material includes peanut shell biochar and cobalt species loaded on the peanut shell biochar; wherein the cobalt species includes metallic cobalt and / or cobalt oxides; and the atomic ratio of cobalt to C in the cobalt-loaded peanut shell biochar composite material is (0.2-0.3):1.
[0020] The atomic ratio is the ratio of the number of cobalt atoms to the number of carbon atoms.
[0021] Furthermore, the cobalt oxide includes Co. 2+ oxides, Co 3+ Oxides.
[0022] Furthermore, the cobalt-loaded peanut shell biochar composite material has a mesoporous structure.
[0023] Furthermore, the total pore volume of the cobalt-supported peanut shell biochar composite material is not less than 0.06 cm³ / g; preferably, the total pore volume of the cobalt-supported peanut shell biochar composite material is 0.06-0.08 cm³ / g.
[0024] Furthermore, the specific surface area of the cobalt-supported peanut shell biochar composite material is not less than 80 m². 2 / g; preferably, the specific surface area of the cobalt-supported peanut shell biochar composite material is 80-120m². 2 / g.
[0025] Thirdly, this application provides the application of the cobalt-supported peanut shell biochar composite material described in the second aspect as a catalyst in activating oxidants.
[0026] Furthermore, the oxidant is peracetic acid, persulfate, perdisulfate, or hydrogen peroxide; preferably, the oxidant is peracetic acid.
[0027] Fourthly, this application provides the application of the cobalt-supported peanut shell biochar composite material described in the second aspect as a catalyst in water treatment.
[0028] Furthermore, the cobalt-supported peanut shell biochar composite material is used as a catalyst to degrade sulfamethoxazole in water.
[0029] Compared with the prior art, this application includes the following beneficial technical effects: This application provides a cobalt-supported peanut shell biochar composite material, its preparation method, and its application. The preparation method involves first preparing peanut shell biochar through a first pyrolysis, and then using the peanut shell biochar as a carrier, through a first hydrothermal reaction followed by a second high-temperature pyrolysis, so that high-content cobalt species are stably loaded onto the peanut shell biochar in a highly dispersed form. This achieves high loading capacity, high catalytic activity, high reaction stability, low leaching rate, and high recycling stability, and shows significant advantages, especially in activating peracetic acid to degrade organic pollutants.
[0030] The cobalt-supported peanut shell biochar composite material prepared in this application has a high cobalt loading. Even when the percentage of cobalt atoms in the composite material is as high as 12% or more, it can still maintain excellent catalytic activity, structural stability, low leaching, and recycling stability. This is attributed to the preparation method of first preparing peanut shell biochar by high-temperature pyrolysis of peanut shell powder in an inert atmosphere, and then using peanut shell biochar as a carrier, as well as the preparation method of first hydrothermal reaction and then high-temperature pyrolysis, as detailed below: In the first pyrolysis, peanut shell powder is placed in an inert atmosphere and heated to 650-750℃ for 1.5-3 hours. This process transforms the peanut shells into peanut shell biochar with a stable carbon skeleton, abundant pores, high specific surface area, and specific surface chemistry of oxygen-containing functional groups (-COOH, -OH). The high specific surface area and abundant pores provide ample space for subsequent large-scale adsorption and cobalt precursors, which is the physical basis for achieving high loading capacity. The stable carbon skeleton and surface oxygen-containing functional groups (-COOH, -OH) are key to the subsequent formation of chemical bonds with cobalt, achieving low leaching of the composite material.
[0031] Peanut shell biochar was dispersed in a concentrated cobalt salt aqueous solution (0.03-0.09 M) and subjected to a hydrothermal reaction at 65-75℃ for several hours. The hydrothermal environment enhanced molecular thermal motion, forcing the high concentration of Co to... 2+Ions diffuse and penetrate deeply into the pores and defects of peanut shell biochar, rather than remaining only on the surface. Heating activates the oxygen-containing functional groups (-COOH, -OH) on the surface of the peanut shell biochar, enabling them to react with Co. 2+ A stronger coordination complexation occurs, resulting in chemical bonding.
[0032] The second pyrolysis involves drying the product after the hydrothermal reaction and then pyrolyzing it at high temperature (750-850℃) under an inert atmosphere. This high temperature causes the cobalt-based precursor to decompose and reduce in situ within the pores and defects of the carbon framework. The porous structure of carbon restricts the migration and growth of the decomposition products, resulting in fine-sized, highly dispersed metallic cobalt and / or cobalt oxide nanoparticles. At this high temperature, strong interactions occur between the cobalt species and the carbon support, forming strong chemical bonds such as Co-C, Co-OC, or Co-O-Si. These bonds firmly bind high cobalt content to the carbon framework, achieving high loading and low leaching. Simultaneously, the high temperature partially graphitizes the carbon support, making the carbon atoms at the defect edges more reactive and capable of forming more stable bonds with the cobalt species.
[0033] This application employs a process of first preparing peanut shell biochar through a first pyrolysis, followed by a hydrothermal reaction, and then a second pyrolysis. This process creates a synergistic effect, with the peanut shell biochar serving as a carrier. It possesses high lignin and silicon content, and abundant mesopores. During the hydrothermal reaction, it acts as numerous additional adsorption and coordination centers, strongly adsorbing Co. 2+ This improves the loading capacity. The high lignin content of peanut shell biochar endows the carbon skeleton with excellent mechanical strength and thermal stability, allowing its pore structure to be maintained or even optimized during subsequent high-temperature pyrolysis. BET characterization data confirms that the specific surface area and total pore volume of the composite material are significantly increased compared to the original peanut shell biochar, avoiding common pore blockage and structural collapse under high loads. During the high-temperature pyrolysis stage, the silicon component in the peanut shell biochar forms strong Co-O-Si chemical bonds with cobalt species. This bonding strength far exceeds the surface physical adsorption or weak coordination effects relied upon by conventional impregnation methods, becoming a key reason for the composite material's extremely low cobalt leaching rate and excellent cycling stability, achieving synergy between raw materials and preparation methods.
[0034] In the first aspect of this application, CoCl2·6H2O is used as the cobalt source. During the hydrothermal reaction-high-temperature pyrolysis process, chloride ions play a crucial role. In the hydrothermal stage, Cl... - With Co 2+The formation of the dichloro complex [CoCl2(H2O)4] provides suitable hydrolysis kinetics, facilitating deep and uniform pre-dispersion of the cobalt precursor within the porous structure of peanut shell biochar, thus laying the foundation for high dispersibility at high loading levels. During subsequent high-temperature pyrolysis, the loaded cobalt chloride precursor (i.e., the solid product obtained from the hydrothermal reaction) decomposes, producing not only cobalt oxides / cobalt metal but also releasing HCl gas. Trace amounts of HCl etch or activate oxygen-containing functional groups or silicon species on the biochar surface, exposing more highly active silicon sites and significantly promoting the formation of strong Co-O-Si bonds between the cobalt species and the support—a unique chemical environment not found in other cobalt salts. Other cobalt salts, such as Co(NO3)2·6H2O, possess strong oxidizing properties due to the presence of nitrate ions, but their coordination ability is weak, and the hydrothermal reaction almost entirely occurs as [Co(H2O)6]. 2+ Cobalt, being strongly positively charged, is easily adsorbed and blocked at the inlet by electrostatic adsorption on the surface of biochar, making deep penetration difficult. During pyrolysis, it decomposes violently at around 200℃, producing a large amount of NOx gas. This rapid process easily leads to the migration and aggregation of cobalt species into larger particles. Lacking the in-situ activation effect of HCl, cobalt has poor dispersibility, and the particles are more prone to growth, resulting in weaker binding to the carrier (lacking the strong bonds facilitated by Cl⁻), leading to a higher leaching rate. Other cobalt salts, such as the sulfate anion in CoSO₄·7H₂O, can react with Co… 2+ It forms an inner or outer complex, but the binding is weak. In the hydrothermal reaction, sulfate ions shield Co to some extent. 2+ Positively charged, but readily reacts with Ca in water. 2+ Precipitation interference can occur; during high-temperature pyrolysis, SOx gas is produced, which is highly corrosive and toxic. SOx may form stable sulfate or sulfite intermediates with cobalt, and these species may still be difficult to completely decompose at 800°C. The residual sulfur can poison the catalytically active sites of cobalt. Other cobalt salts, such as cobalt acetate (Co(CH3COO)2·4H2O), readily form complexes with their acetate anions, but the acetate itself may hydrolyze or decompose in high-temperature hydrothermal processes, complicating the system. During high-temperature pyrolysis, organic matter decomposes, producing a reducing atmosphere (CO, H2), which is conducive to the formation of metallic cobalt (Co). 0 However, the process generates a large amount of carbon-containing volatile gases, which may cause disordered carbon deposition, block the pores of the material, make the process difficult to control in terms of repeatability, and the pyrolysis carbon deposition may mask the active sites, and the specific surface area may decrease.
[0035] This application employs a hydrothermal reaction to allow cobalt to fully contact and combine with the functional groups on the surface of peanut shell biochar in the liquid phase. Subsequent pyrolysis at elevated temperatures decomposes and transforms the cobalt species, forming strong chemical bonds (such as Co-OC and Co-NC) with the carbon matrix. This ensures that the cobalt species in the cobalt-loaded peanut shell biochar composite material are uniformly loaded into the defects and pores of the peanut shell biochar, effectively preventing cobalt species aggregation and leaching, and improving the catalytic activity and stability of the material. The composite material possesses a rich mesoporous structure, which is beneficial for the diffusion and mass transfer of reactants and products. Simultaneously, high-temperature pyrolysis promotes the graphitization of the carbon matrix, improving the overall conductivity of the composite material and synergistically optimizing electron transfer efficiency. The Co present in the composite material... 2+ The presence of cobalt species with multiple valence states, such as Co³⁺, facilitates rapid electron transfer, thereby enabling efficient and stable activation of oxidants like peracetic acid. This achieves a synergistic construction of the microstructure and active components.
[0036] The composite material prepared in this application possesses dual functions of adsorption and enrichment as well as catalytic oxidation. Its high specific surface area fully exposes active sites, enabling strong synergy with oxidants and exhibiting rapid and efficient removal capabilities for recalcitrant organic pollutants in water (especially antibiotics such as sulfamethoxazole). The strong chemical bonds (Co-O-Si, Co-OC) of the composite material ensure structural stability and extremely low metal leaching during multiple catalyst cycles, avoiding secondary pollution. Using inexpensive and readily available agricultural waste such as peanut shells as raw material aligns with the green chemistry concept of treating waste with waste, offering significant advantages such as low cost, environmental friendliness, and ease of promotion.
[0037] This application achieves a synergistic effect through the precise design and high matching between a peanut shell biochar carrier, a two-step preparation method involving hydrothermal reaction followed by high-temperature pyrolysis, and the application of activated peroxides (such as PAA). This overcomes the technical bottleneck of high-loaded cobalt catalysts, which struggle to balance activity, stability, and dispersibility, and provides a novel, efficient, stable, and green catalyst solution for advanced oxidation water treatment technology.
[0038] In summary, this application employs a preparation process involving a first pyrolysis to prepare peanut shell biochar, followed by a hydrothermal reaction and a second pyrolysis. Cobalt species, including metallic cobalt and / or cobalt oxides, are loaded onto the peanut shell biochar. The resulting cobalt-loaded peanut shell biochar composite material exhibits a high cobalt loading capacity and extremely high dispersibility of the cobalt species, providing highly active sites for activating oxidants. Furthermore, the leaching of active cobalt species is significantly inhibited, demonstrating high stability for recycling. The peanut shell biochar, acting as a carrier, provides a high specific surface area and conductivity, promoting electron transfer and adsorbing and enriching pollutants, thereby increasing the local reaction concentration. The composite material prepared by loading cobalt species onto peanut shell biochar has a stable structure, enhancing its catalytic efficiency for oxidants. Attached Figure Description
[0039] The present application will be described in further detail below with reference to the accompanying drawings and preferred embodiments. However, those skilled in the art will understand that these drawings are drawn only for the purpose of explaining the preferred embodiments and therefore should not be construed as limiting the scope of this disclosure. Furthermore, unless specifically indicated, the drawings are only schematic representations of the composition or structure of the described objects and may contain exaggerated depictions, and the drawings are not necessarily drawn to scale.
[0040] Figure 1 Figures show the structural characterization of peanut shell biochar, cobalt-supported peanut shell biochar composite material, and used cobalt-supported peanut shell biochar composite material, as well as the degradation of sulfamethoxazole in different systems. Among them, (a) is the XRD spectrum; (b) is the FTIR spectrum; (c) is the nitrogen adsorption-desorption isotherm; and (d) is the degradation of sulfamethoxazole in different systems.
[0041] Figure 2 The image shows the Raman spectra of the peanut shell biochar and cobalt-supported peanut shell biochar composite materials prepared in Example 1.
[0042] Figure 3 The diagram shows the pseudo-first-order kinetic rate constants for the degradation of sulfamethoxazole in different reaction systems.
[0043] Figure 4 The images show the scanning electron microscope (SEM), transmission electron microscope (TEM), and EDS elemental analysis of the peanut shell biochar and cobalt-supported peanut shell biochar composite prepared in Example 1; where (a) is the SEM image of the peanut shell biochar; (b) is the C... 0.09 (c) is the SEM image of the cobalt-loaded peanut shell biochar composite material; (d) is the TEM image of the cobalt-loaded peanut shell biochar composite material; (e) is the surface distribution map of C element in the EDS element of the cobalt-loaded peanut shell biochar composite material; (f) is the surface distribution map of O element in the EDS element of the cobalt-loaded peanut shell biochar composite material; (g) is the distribution map of Co element in the EDS element of the cobalt-loaded peanut shell biochar composite material.
[0044] Figure 5 XPS analysis images of peanut shell biochar, cobalt-supported peanut shell biochar composite material and used cobalt-supported peanut shell biochar composite material are shown. (a) is the full spectrum; (b) is the C 1s spectrum; (c) is the O 1s spectrum; and (d) is the Co 2p spectrum.
[0045] Figure 6 This is a cyclic experimental diagram of cobalt-loaded peanut shell biochar composite material. Detailed Implementation
[0046] The following is in conjunction with the appendix Figures 1 to 6This application will be described in detail.
[0047] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0048] Raw materials and reagents Peanut shells: purchased from Taobao.
[0049] Cobalt chloride hexahydrate: purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).
[0050] Peracetic acid: purchased from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China).
[0051] Unless otherwise specified, all other reagents used in the embodiments of this application are from conventional commercially available products.
[0052] Detection methods Sulfamethoxazole (SMX) concentration determination The concentration of sulfamethoxazole (SMX) was determined using a Shimadzu ultra-high performance liquid chromatography-triple quadrupole mass spectrometry (LC-MS / MS, model LC20AD, 8045, Shimadzu Corporation, Japan). LC conditions: Separation was performed using a C18 column (3 μm, 2.1 × 100 mm) with isocratic elution (mobile phase A (water containing 0.1% formic acid) 70%, mobile phase B (acetonitrile) 30%), flow rate 0.3 mL / min, column temperature 35 °C.
[0053] Mass spectrometry conditions: ESI ion source, positive ion mode; precursor ion m / z 254.1, daughter ions m / z 92 (collision energy -28V) and m / z 156 (collision energy -16V). Injection volume 2 μL, retention time 4 min.
[0054] Characterization methods Material morphology analysis was performed using a field emission scanning electron microscope (SEM, model SU8230, Hitachi Regulus, Japan) and a transmission electron microscope (TEM, model Talos F200S, Thermo Fisher Scientific, USA).
[0055] Specific surface area and pore size distribution were determined by nitrogen physical adsorption (BET, model ASAP 2460, McMurray, USA).
[0056] Phase structure data were acquired using an X-ray diffractometer (XRD, model X'Pert Pro MPD, SmartLab, Japan).
[0057] The molecular structure and functional groups of the material were analyzed using a Fourier transform infrared spectrometer (FT-IR, model TENSOR 27, Bruker, Germany).
[0058] The elemental chemical state of the material surface was characterized using an X-ray photoelectron spectroscopy (XPS, model AXIS SUPRA, Shimadzu, Japan).
[0059] The structural defects and stability of the material were analyzed using a high-resolution Raman spectrometer (Raman, model LabRAM HR evolution, Horiba, France).
[0060] The specific implementation method of this application is as follows. Example 1
[0061] This embodiment provides cobalt-loaded peanut shell biochar (C 0.09 The preparation method of the BC composite material is as follows: Peanut shell powder of 200 mesh was placed in a nitrogen atmosphere and heated to 700°C at a heating rate of 5°C / min for 2 hours. The resulting peanut shell biochar powder was repeatedly washed with ultrapure water until neutral and then dried at 80°C for 3 hours to obtain peanut shell biochar (BC).
[0062] 0.5 g of peanut shell biochar was uniformly dispersed in 100 mL of CoCl2·6H2O solution (0.09 M), with a mass ratio of peanut shell biochar to CoCl2·6H2O of 1:4.28. The reaction was carried out under continuous magnetic stirring (70 °C, 4 h). Subsequently, the slurry was dried at 80 °C for 12 h to obtain a solid product, which was then pyrolyzed at 800 °C for 3 h under a nitrogen atmosphere at a heating rate of 5 °C / min. The product was then washed sequentially with ethanol and ultrapure water (3 times each) until the washings were neutral, and finally dried under vacuum at 80 °C for 8 h to obtain a cobalt-supported peanut shell biochar composite material.
[0063] Based on Example 1, this application prepared cobalt-loaded peanut shell biochar composite materials with different cobalt loading ratios. The CoCl2·6H2O solutions were 0.03M and 0.06M, respectively, and the rest were exactly the same as in Example 1. The specific parameters are shown in Table 1.
[0064] Table 1. Parameters for different cobalt loading ratios
[0065] Application Example 1 This application example uses the cobalt-supported peanut shell biochar composite material prepared in Example 1 for the treatment of water containing sulfamethoxazole. The specific process is as follows: A 5 mg / L sulfamethoxazole solution was placed in a 250 mL glass reactor; then a 200 mg / L cobalt-supported peanut shell biochar composite material C was added. 0.09 BC was used as a catalyst, with a total volume concentration of 200 mg / L. The reaction was carried out at 25°C with constant magnetic stirring at 500 rpm, and the pH was adjusted to 6.8. 0.2 mM peracetic acid solution was added to initiate the reaction, bringing the total volume of the reaction system to 200 mL. Samples were taken periodically using a precision pipette, 1 mL each time. Immediately after sampling, the reaction was quenched with 50 μL of 0.1 M Na₂S₂O₃ solution, and the sample was filtered through a 0.22 μm needle filter before analysis. Used cobalt-supported peanut shell biochar composite material was collected by centrifugation, thoroughly rinsed with ultrapure water, and dried in a vacuum oven at 60°C.
[0066] Based on Application Example 1, the cobalt-supported peanut shell biochar composite material, peracetic acid, and peanut shell biochar prepared in Examples 2 and 3 were used to treat water containing sulfamethoxazole. The treatment process was the same as in Application Example 1, and the specific parameters are shown in Table 2.
[0067] Table 2 Application Example Parameters
[0068] This application compares the peanut shell biochar prepared in Example 1 (denoted as BC) and the cobalt-supported peanut shell biochar composite material prepared in Example 1 (denoted as C). 0.09 BC), and the used cobalt-loaded peanut shell biochar composite material collected in Example 1 (denoted as Used C). 0.09 XPS analysis was performed on BC, and the results are shown in Table 3.
[0069] Table 3. Elemental composition (atomic percentage, %) based on XPS analysis
[0070] Table 3 shows that cobalt-loaded peanut shell biochar (C 0.09The Co atomic percentage in the BC composite material is as high as 12.75%, which directly confirms the successful loading of a high cobalt content. Simultaneously, the C content decreases to 49.39%, and the O content increases to 30.99%, indicating that cobalt exists mainly in the form of oxides / hydroxides, with the introduction of additional oxygen. In the used cobalt-loaded peanut shell biochar composite material, the Co content decreased from 12.75% to 6.80%, which is not a simple leaching process. The C content rebounded to 60.36%, and the O content decreased to 26.05%. This is attributed to the consumption or transformation of unstable, high-valence cobalt species on the surface during the reaction, while exposing more carbon substrate, and changes in the oxygen-containing functional groups on the carbon substrate surface. It is also noteworthy that approximately 53% of Co was retained (6.80 / 12.75), indicating that the material has good structural stability and that the active components are not easily completely lost.
[0071] The specific surface area and pore volume of the peanut shell biochar prepared in Example 1 and the cobalt-supported peanut shell biochar composites prepared in Examples 1-3 were tested in this application, and the results are shown in Table 4.
[0072] Table 4 C x Characterization results of specific surface area and pore volume of BC composite material
[0073] This application characterized the peanut shell biochar prepared in Example 1, the cobalt-supported peanut shell biochar composite material prepared in Examples 1-3, the used cobalt-supported peanut shell biochar composite material collected in Application Example 1, and the used peanut shell biochar composite material collected in Comparative Application Example 2, including XRD, FTIR, and nitrogen adsorption-desorption detection analysis. Furthermore, this application investigated the degradation of sulfamethoxazole in Examples 1-3 and Comparative Application Examples 1-2. The results are as follows: Figure 1 As shown, BC represents peanut shell biochar, C 0.03 BC indicates cobalt-loaded peanut shell biochar (C 0.03 BC) composite material, C 0.06 BC indicates cobalt-loaded peanut shell biochar (C 0.06 BC) composite material, C 0.09 BC indicates cobalt-loaded peanut shell biochar (C 0.09 BC) composite material, Used C 0.09 BC represents the collected cobalt-loaded peanut shell biochar (C 0.09 BC) composite material, PAA indicates that the catalyst is peracetic acid, C 0.03 BC+PAA indicates that the catalyst is cobalt-supported peanut shell biochar (C 0.03 BC) Composite material and peracetic acid system, C 0.06BC+PAA indicates that the catalyst is cobalt-supported peanut shell biochar (C 0.06 BC) Composite material and peracetic acid system, C 0.09 BC+PAA indicates that the catalyst is cobalt-supported peanut shell biochar (C 0.09 BC) composite material and peracetic acid system.
[0074] This application also conducted Raman spectroscopy analysis on the peanut shell biochar prepared in Example 1 and the cobalt-supported peanut shell biochar composite material prepared in Example 1, and the results are as follows: Figure 2 As shown.
[0075] This application investigated the pseudo-first-order kinetics of the treatment process of water containing sulfamethoxazole in Comparative Application Example 1 and Application Examples 1-3, specifically studying the pseudo-first-order kinetics of sulfamethoxazole degradation in different catalyst reaction systems. The results are as follows: Figure 3 As shown.
[0076] Depend on Figure 1 XRD analysis (a) shows that the characteristic peak observed at 2θ 26.3° of the original peanut shell biochar corresponds to the (002) crystal plane of graphitic carbon, indicating its amorphous carbon structure. Compared with single biochar, the cobalt-supported peanut shell biochar composite material shows the unique crystallization spectrum of metallic cobalt, indicating that cobalt has been successfully introduced into the peanut shell biochar matrix. The diffraction peaks appearing at 20.9°, 36.5°, 42.4°, 44.5°, 51.5°, and 76.2° in the figure are assigned to CoO2, CoO, and Co, respectively. 0 The crystal forms have (001), (111), (200), (002), (101), and (110) crystal planes. It is worth noting that CoO2 and Co... 0 The intensity of the diffraction peaks is positively correlated with the increase of cobalt loading concentration.
[0077] like Figure 1 As shown in (b), the cobalt-supported peanut shell biochar composite material exhibits high cobalt content at 3438, 1633, and 1091 cm⁻¹. -1 The three FT-IR characteristic absorption bands at 550 cm⁻¹ correspond to O–H, C=O, and C–O bonds, respectively. Meanwhile, the cobalt-supported peanut shell biochar composite material exhibits [missing information - likely a specific characteristic or characteristic] at 550 cm⁻¹. -1 An additional absorption band appears, attributed to the stretching vibration of the Co–O bond. The intensity of the Co–O absorption band gradually decreases with increasing cobalt loading, indicating that cobalt oxide species gradually migrate to other cobalt species (such as CoO2 and Co). 0 This change is consistent with the XRD results.
[0078] Depend on Figure 1As shown in (c), the N2 adsorption-desorption isotherm of the cobalt-loaded peanut shell biochar composite exhibits a type IV curve structure, indicating the presence of a mesoporous structure. Combined with Table 4, the specific surface area gradually increases with increasing cobalt loading, with the original peanut shell biochar (BC) having a specific surface area of 71.63 m². 2 / g, while the specific surface area of the cobalt-supported peanut shell biochar composite material systematically increases, C 0.09 The BC composite material has the largest specific surface area, reaching 118.06 m². 2 A larger specific surface area and pore volume per g mean more exposed active sites, faster mass transfer rates, and better catalytic activation performance. Therefore, the composite material provided in this application not only loads highly active cobalt species but also optimizes and improves the pore structure of the peanut shell biochar support itself, achieving a specific surface area of over 118 m² / g and a total pore volume of over 0.076 cm³ / g. This provides abundant contact interfaces and transport channels for reactants, which is an important reason for its ultra-high catalytic activity.
[0079] In addition, Raman spectroscopy analysis ( Figure 2 The study further elucidated the structural changes caused by the introduction of cobalt. Compared with the original peanut shell biochar, the cobalt-loaded peanut shell biochar composite exhibited a higher defect carbon to graphite carbon strength ratio (ID / IG), indicating that cobalt loading introduced structural defects by partially disrupting the graphite skeleton of the peanut shell biochar.
[0080] Figure 1 Figure (d) shows the degradation efficiency of sulfamethoxazole in different systems. Direct oxidation with peracetic acid showed limited degradation efficiency (approximately 19.7%). Meanwhile, the cobalt-supported peanut shell biochar composite showed an adsorption rate of only 8.2% for sulfamethoxazole; conversely, peanut shell biochar alone achieved an adsorption rate of 67.8%, attributed to the abundant functional groups and excellent specific surface area of peanut shell biochar. This comparison highlights the trade-off between adsorption capacity and catalytic function caused by cobalt modification. Notably, as the cobalt concentration increased from 0.03 M to 0.09 M, the degradation efficiency of sulfamethoxazole increased from 84.4% to 90.1%, while the pseudo-first-order kinetic constant (kobs) of sulfamethoxazole degradation increased from 0.00846 min⁻¹. -1 Increased to 0.00981 min -1 ( Figure 3The cobalt-supported peanut shell biochar composite / peracetic acid system achieved an excellent sulfamethoxazole degradation efficiency of 90.1% within 4 minutes, indicating that the cobalt-supported peanut shell biochar composite can effectively activate peracetic acid to generate free radicals, thereby oxidizing pollutants. The results show that the introduction of cobalt can transform peanut shell biochar from a passive adsorbent into an active peracetic acid activator, thus achieving rapid and efficient sulfamethoxazole degradation. Based on specific surface area optimization, catalytic performance, and structural characterization, the cobalt-supported peanut shell biochar composite was identified as the most effective catalyst and was therefore selected for subsequent research.
[0081] This application presents scanning electron microscopy, transmission electron microscopy, and EDS elemental analyses of the peanut shell biochar and cobalt-supported peanut shell biochar composite materials prepared in Example 1. The results are as follows: Figure 4 As shown. By Figure 4 As shown in (a), the original peanut shell biochar exhibits a blocky structure, while the surface of the cobalt-loaded peanut shell biochar composite material shows uniformly distributed cobalt-containing spherical particles. Figure 4 (b) Figure 4 As shown in (c), the cobalt-supported peanut shell biochar composite material has a uniform layered structure. From... Figure 4 In image (d), the interplanar spacings of 0.24 nm for the CoO(111) crystal plane, 0.20 nm for the Co(111) crystal plane, and 0.24 nm for the CoO2(100) crystal plane are clearly visible. Figure 4 The C, O and Co elements in the cobalt-supported peanut shell biochar composite are uniformly distributed.
[0082] This application performed XPS analysis on the peanut shell biochar prepared in Example 1, the cobalt-supported peanut shell biochar composite material, and the used cobalt-supported peanut shell biochar composite material collected in Example 1. The results are as follows: Figure 5 As shown. The chemical states of different elements in the cobalt-supported peanut shell biochar composite material were characterized by X-ray photoelectron spectroscopy. Figure 5 (and Table 3). Figure 5 Full spectrum analysis in (a) confirmed the coexistence of Co, C and O elements, verifying that cobalt has been successfully loaded into the peanut shell biochar matrix. Figure 5 The medium (b) high-resolution C1s spectrum shows three peaks, corresponding to graphitic carbon (284.8 eV), C–O (286.39 eV), and C=O (288.94 eV), respectively. Notably, compared to bulk peanut shell biochar (BC), the oxygenated carbon content in the cobalt-supported peanut shell biochar composite increased from 9.04% to 29.54%, while the graphitic carbon content decreased from 90.96% to 70.46%, indicating partial carbon oxidation. Figure 5In the O 1s spectrum in (c), the two peaks with binding energies of 529.9 eV and 531.6 eV are attributed to surface-adsorbed oxygen and lattice oxygen, respectively. ads The strength increased from 66.87% in peanut shell biochar to C 0.09 70% of BC is attributed to the increased specific surface area of the cobalt-supported peanut shell biochar composite, which enhances O ads Adsorption. Figure 5 The middle (d) Co 2p spectrum shows characteristic spin-orbit splitting (Co 2p3 / 2 and Co 2p1 / 2), and satellite peaks at 787.2 eV and 803.4 eV indicate the presence of Co. 2+ Oxidation state, other characteristic peaks are Co 0 (795.86 eV), Co 3+ (781.0and 797.1 eV) and Co 2+ (783.4 and 798.3 eV. This multivalent system enables synergistic activation of peracetic acid (PAA): Co) 0 and Co 2+ The oxidative cleavage pathway is driven by electron transfer, while Co 3+ This mediates reduction and activation to generate highly active CH3C(O)OO• free radicals.
[0083] Based on Application Example 1, this application evaluates the reusability of cobalt-loaded peanut shell biochar composite material through five consecutive cyclic experiments. After each round of experiments, the used C200C ...0C2000000C20000000C200000000 0.09 The BC composite material was thoroughly rinsed with ultrapure water and dried in a vacuum oven at 60°C for subsequent reuse. The results are as follows: Figure 6 As shown. By Figure 6 Cyclic experiments showed that after five cycles, the degradation efficiency of sulfamethoxazole decreased slightly from 90.1% to 81.8%. This is attributed to the cumulative degradation products covering the surface active sites of the cobalt-supported peanut shell biochar composite. This result demonstrates the good reusability and stability of the cobalt-supported peanut shell biochar composite in the cobalt-supported peanut shell biochar composite / peracetic acid system.
[0084] The present application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present application. The descriptions of the embodiments above are only for the purpose of helping to understand the present disclosure and its core ideas. It should be noted that those skilled in the art can make several improvements and modifications to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.
Claims
1. A method for preparing a cobalt-supported peanut shell biochar composite material, characterized in that, Includes the following steps: Peanut shell biochar was dispersed in an aqueous solution of CoCl2·6H2O and subjected to a hydrothermal reaction. After the reaction was completed, the product was dried to obtain a solid product. The solid product was then subjected to pyrolysis again in an inert atmosphere at a temperature of 750-850℃ to obtain the cobalt-supported peanut shell biochar composite material. The mass ratio of peanut shell biochar to cobalt salt is 1:(1-5). The conditions for hydrothermal reactions include a reaction temperature of 65℃-75℃; The method for preparing peanut shell biochar includes: placing peanut shell powder in an inert atmosphere and heating it to pyrolyze it to obtain peanut shell biochar powder.
2. The preparation method of the cobalt-supported peanut shell biochar composite material as described in claim 1, characterized in that, The concentration of the CoCl2·6H2O aqueous solution is 0.03M-0.09M; The conditions for the hydrothermal reaction include a reaction time of 3-5 hours.
3. The preparation method of the cobalt-supported peanut shell biochar composite material as described in claim 1, characterized in that, The drying conditions include a drying temperature of 75℃-85℃ and a drying time of 10-14 hours.
4. The preparation method of the cobalt-supported peanut shell biochar composite material as described in claim 1, characterized in that, The temperature is increased to 750-850℃ at a rate of 4-6℃ / min, and the pyrolysis time is 2-4 hours.
5. The method for preparing the cobalt-supported peanut shell biochar composite material as described in claim 1, characterized in that, The product after pyrolysis at elevated temperature is washed repeatedly with ethanol and ultrapure water until the washing solution is neutral, and then dried to obtain the cobalt-supported peanut shell biochar composite material.
6. The method for preparing the cobalt-supported peanut shell biochar composite material as described in claim 1, characterized in that, The method for preparing the peanut shell biochar includes: repeatedly washing the obtained peanut shell biochar powder with ultrapure water until neutral, and drying it to obtain the peanut shell biochar.
7. The method for preparing the cobalt-supported peanut shell biochar composite material as described in claim 6, characterized in that, In the preparation method of peanut shell biochar, the pyrolysis is carried out by heating to 650-750℃ at a heating rate of 4-6℃ / min and pyrolyzing for 1.5-3 hours. The drying temperature is 75-85℃; the drying time is 2-4 hours.
8. A cobalt-supported peanut shell biochar composite material, prepared by the method for preparing the cobalt-supported peanut shell biochar composite material according to any one of claims 1-7, characterized in that, The cobalt-loaded peanut shell biochar composite material includes peanut shell biochar and cobalt species loaded on the peanut shell biochar; wherein the cobalt species includes metallic cobalt and / or cobalt oxides; the atomic ratio of cobalt to C in the cobalt-loaded peanut shell biochar composite material is (0.2-0.3):
1.
9. The cobalt-supported peanut shell biochar composite material as described in claim 8, characterized in that, The cobalt-supported peanut shell biochar composite material has a mesoporous structure; the total pore volume of the cobalt-supported peanut shell biochar composite material is not less than 0.06 cm³ / g; And / or, the specific surface area of the cobalt-supported peanut shell biochar composite material is not less than 80 m². 2 / g.
10. The application of the cobalt-supported peanut shell biochar composite material as described in any one of claims 8-9 as a catalyst in the activation of peracetic acid.