HPCACM-coated Co3O4 composite material, preparation method and application
By preparing HPCACM@Co3O4 composite materials, the problem of synergistic activation of straw cellulose-based water treatment materials was solved, achieving efficient activation of potassium persulfate and synergistic degradation of pollutants, improving the efficiency of water pollution treatment and promoting the high-value utilization of agricultural waste.
Patent Information
- Application Number
- CN202511860396.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-11
- Publication Date
- 2026-02-10
AI Technical Summary
Existing straw cellulose-based water treatment materials lack a synergistic activation function design with potassium persulfate, resulting in low degradation efficiency, narrow applicability, and poor reusability, making it difficult to meet the removal needs of recalcitrant pollutants in complex water bodies.
Cellulose was extracted from straw, and hollow porous cellulose acetate fiber membranes and hollow porous cellulose acetate-derived carbon fiber membranes were prepared by coaxial electrospinning. These membranes were then further combined with Co3O4 to form HPCACM@Co3O4 composite material, which achieved efficient activation of potassium persulfate and synergistic degradation of pollutants.
This composite material has a high specific surface area and a micro-mesoporous hierarchical structure, which can efficiently activate potassium persulfate, significantly improve the efficiency of water pollution treatment, and promote the high-value utilization of agricultural waste.
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Figure CN121490766A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of composite material technology, and particularly relates to an HPCACM@Co3O4 composite material, its preparation method, and its application. Background Technology
[0002] When straw is washed into water bodies by rainwater, its main component, cellulose, has a stable structure and a long natural degradation cycle. It will adsorb heavy metal ions, organic dyes, and pollutants such as nitrogen and phosphorus, which will aggravate eutrophication and destroy the aquatic ecological balance.
[0003] Cellulose, as an abundant natural polymer, possesses a porous structure, high specific surface area, and abundant hydroxyl functional groups, making it an ideal precursor for the preparation of functional materials. Potassium persulfate, as a highly efficient oxidant, is widely used in the degradation of water pollution; however, it requires activation to fully realize its oxidizing properties. Traditional activation methods (such as metal ion activation) suffer from drawbacks such as secondary pollution and poor stability. Existing straw cellulose-based water treatment materials are mostly single-adsorption products, lacking functional designs for synergistic activation with potassium persulfate. These materials suffer from low degradation efficiency, narrow applicability, and poor reusability, making it difficult to meet the removal requirements of recalcitrant pollutants in complex water bodies.
[0004] Therefore, developing composite activation materials based on straw cellulose to achieve efficient activation of potassium persulfate and synergistic degradation of pollutants, with the dual value of resource recycling and environmental governance, is of great practical significance for promoting the high-value utilization of agricultural waste and improving the efficiency of water pollution control. Summary of the Invention
[0005] To address the aforementioned problems, this invention provides an HPCACM@Co3O4 composite material, its preparation method, and its application. By extracting cellulose from straw and preparing rice straw-derived hollow porous cellulose acetate membranes, carbon fiber membranes, and HPCACM@Co3O4 composite materials through coaxial electrospinning, the invention achieves the goal of efficiently activating potassium persulfate and synergistically degrading pollutants.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] In a first aspect, the present invention provides a method for preparing HPCACM@Co3O4 composite material, comprising the following steps:
[0008] Preparation of rice straw-derived cellulose;
[0009] Preparation of rice straw-derived cellulose acetate (CA);
[0010] Preparation of hollow porous cellulose acetate fiber membrane (HPCAFM);
[0011] Preparation of hollow porous cellulose acetate-derived carbon fiber membranes (HPCACM);
[0012] Prepare HPCACM@Co3O4 composite material.
[0013] In some possible implementations, the preparation of rice straw-derived cellulose (CA) includes the following steps:
[0014] Wash and dry the rice straw, then crush it with a pulverizer, sieve it, and take 80-100 mesh rice straw powder for later use.
[0015] The rice straw powder and the aqueous ethanol solution were mixed at a solid-liquid ratio of 1g:(8-20)mL, placed in a closed reactor, and heated to react. After the reaction was completed, the mixture was filtered to obtain rice straw residue, which was then dried to obtain pretreated rice straw.
[0016] The pretreated rice straw and potassium hydroxide solution were mixed in a certain proportion and added to a flask. The ambient temperature was set at 85-95℃, and the mixture was stirred to react. After the reaction was completed, the alkali-treated rice straw solid was filtered out and mixed with a 4-6wt% hydrogen peroxide solution at a solid-liquid ratio of 1g:(90-110)ml. The mixture was heated and stirred at 65-5℃ for 1.5-2.5h to obtain the rice straw-derived cellulose.
[0017] The preparation of rice straw-derived cellulose acetate (CA) includes the following steps:
[0018] The rice straw-derived cellulose was mixed with glacial acetic acid, and 98% concentrated sulfuric acid was added as a catalyst. Acetic anhydride was then added, and an acetylation reaction was carried out at 30-50°C for 1-3 hours. After the reaction was completed, distilled water was added to the acetylated solution to precipitate the cellulose. The solution was then vacuum filtered and washed with deionized water until the filtrate was neutral. Finally, the filtered solid was freeze-dried to obtain the rice straw-derived cellulose acetate.
[0019] In some possible embodiments, the preparation of the hollow porous cellulose acetate fiber membrane (HPCAFM) using coaxial electrospinning and hydrothermal etching includes the following steps:
[0020] Preparation of coaxial electrospinning shell spinning solution: The coaxial electrospinning shell spinning solution contains three polymers: polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and rice straw-derived cellulose acetate (CA), with a mass ratio of PAN:PVP:CA = 1:(2.0-4.0):(3.0-5.0), and the total mass of the three polymers to the volume ratio of the solvent N,N-dimethylacetamide (DMAc) is (1.5-4.0):10 (g / mL);
[0021] Preparation of coaxial electrospinning core layer spinning solution: The coaxial electrospinning core layer spinning solution is a DMAc solution of polyvinylpyrrolidone (PVP) with a mass-to-volume ratio of (1.5-3.5):10 (g / mL).
[0022] At room temperature, with a positive voltage of 15-25kV and a negative voltage of 4-6kV, the spinning needle can be translated 0-5cm along the receiver direction. The distance between the spinning needle and the receiver is 14-18cm, and the spinning humidity is 50%-70%. Through the coaxial electrospinning method, the coaxial electrospinning shell layer spinning solution and the coaxial electrospinning core layer spinning solution are simultaneously pumped to perform spinning, thereby obtaining a nanofiber membrane; the nanofiber membrane is a core-shell structured nanofiber membrane.
[0023] The nanofiber membrane was placed in a pressure-resistant container, and deionized water was added. The liquid-to-solid volume-to-mass ratio was controlled to be no less than 80 mL / g, and no less than 80 mL of deionized water was required for every 1 g of nanofiber membrane to ensure that the nanofiber membrane was fully submerged. The container was then sealed and heat-treated at 110-130℃ for 2-4 hours to remove polyvinylpyrrolidone (PVP). After the reaction system was naturally cooled to room temperature, the reacted nanofiber membrane was removed, washed with deionized water until neutral, and finally freeze-dried to obtain the HPCAFM.
[0024] In some possible embodiments, the preparation of the hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM) includes the following steps:
[0025] HPCAFM was pre-oxidized in a muffle furnace and carbonized in a tubular furnace to obtain HPCACM;
[0026] The muffle furnace pre-oxidation includes: heating to 250-300°C in air or an oxygen-containing atmosphere at a heating rate of 0.5-2°C / min, maintaining the temperature, and reacting for 0.5-2 hours;
[0027] The tubular furnace carbonization process includes: heating to 550-650°C at a rate of 2-10°C / min under an inert atmosphere, maintaining the temperature, and reacting for 0.5-2 hours to obtain the HPCACM.
[0028] In some possible implementations, the preparation of the HPCACM@Co3O4 composite material includes the following steps:
[0029] The HPCACM carrier and Co(NO3)2·6H2O are dispersed in anhydrous ethanol at a certain mass molar ratio, with the amount of ethanol controlled at 60-100 mL per gram of carrier. The mixture is stirred for 0.5-2 h, and then a certain amount of NH4HCO3 is added. The mixture is stirred for another 4-8 h. The reactants are then removed and dried at 60-80℃ for 6-12 h to obtain the precursor. The precursor is placed in a muffle furnace and heated to 250-350℃ at a programmed heating rate of 1-5℃ / min under an air atmosphere. The temperature is maintained and calcined for 1-3 h. After natural cooling, the HPCACM@Co3O4 composite material is obtained.
[0030] In some possible embodiments, the volume fraction of the aqueous ethanol solution is 60-80%, the pretreated rice straw and potassium hydroxide solution are mixed at a solid-liquid ratio of 1g:(17.5-22.5)ml, the concentration of the potassium hydroxide solution is 4-6wt%, the heating reaction temperature is 160-240℃, and the reaction time is 2-3h.
[0031] In some possible embodiments, the rice straw-derived cellulose is mixed with glacial acetic acid at a solid-liquid ratio of 1g:(14-18)ml, the amount of concentrated sulfuric acid used is 1-3% of the volume of glacial acetic acid, and the mass ratio of the rice straw-derived cellulose to the acetic anhydride is 1:(3-5).
[0032] In some possible embodiments, the HPCACM and Co(NO3)2·6H2O are dispersed in anhydrous ethanol at a mass molar ratio of 1 g:(7.7-69.2) mmol; the amount of Co(NO3)2·6H2O added is controlled based on the HPCACM carrier so that the theoretical mass loading of cobalt in the composite material is 4.6%-41.4%; the molar ratio of Co(NO3)2·6H2O to NH4HCO3 is 1:(2.5-3.5).
[0033] Secondly, the present invention provides an HPCACM@Co3O4 composite material, which is obtained based on the preparation method of the first aspect.
[0034] Thirdly, the present invention also provides an application of the HPCACM@Co3O4 composite material, which, based on the composite material described in the second aspect, is applied to the degradation of water pollutants; the composite material has a high specific surface area and a micro-mesoporous hierarchical structure, providing a rich active interface for catalytic reactions, which helps to promote the mass transfer between reactants and products and efficiently activate potassium persulfate.
[0035] This invention provides an HPCACM@Co3O4 composite material, its preparation method, and its application. Rice straw-derived cellulose is extracted from straw, and then rice straw-derived cellulose acetate (CA), hollow porous cellulose acetate fiber membrane (HPCAFM), and hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM) are prepared sequentially to create the HPCACM@Co3O4 composite material. This novel composite material possesses a high specific surface area, providing abundant active interfaces for catalytic reactions. Its unique micro-mesoporous hierarchical structure further facilitates mass transfer between reactants and products, enabling efficient activation of potassium persulfate and exhibiting excellent catalytic degradation performance. This has significant practical implications for promoting the high-value utilization of agricultural waste and improving the efficiency of water pollution control. Attached Figure Description
[0036] Figure 1 SEM of hollow porous cellulose acetate fiber membrane HPCAFM;
[0037] Figure 2 SEM of hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM);
[0038] Figure 3 TEM of a hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM);
[0039] Figure 4 HPCACM@Co3O4SEM;
[0040] Figure 5 HPCACM@Co3O4TEM;
[0041] Figure 6 The elemental distribution of HPCACM@Co3O4;
[0042] Figure 7 XRD patterns of HPCACM, Co3O4 and HPCACM@Co3O4 composites;
[0043] Figure 8 N2 adsorption-desorption isotherms and pore size distributions of HPCACM, Co3O4 and HPCACM@Co3O4 composites;
[0044] Figure 9 The degradation efficiency of TC in seven different systems;
[0045] Figure 10 The effects of different Co3O4 loading, catalyst dosage, PMS concentration and initial pH value on TC degradation;
[0046] Figure 11 The effects of different interfering ions on TC degradation;
[0047] Figure 12 The XRD patterns of the catalyst before and after the reaction are shown in the three-cycle test of TC degradation. Detailed Implementation
[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0049] Example 1
[0050] This embodiment provides a method for preparing HPCACM@Co3O4 composite material, including the following steps:
[0051] Preparation of rice straw-derived cellulose;
[0052] Preparation of rice straw-derived cellulose acetate (CA);
[0053] Preparation of hollow porous cellulose acetate fiber membrane (HPCAFM);
[0054] Preparation of hollow porous cellulose acetate-derived carbon fiber membranes (HPCACM);
[0055] Preparation of HPCACM@Co3O4 composite material;
[0056] The preparation of rice straw-derived cellulose (CA) includes the following steps:
[0057] Wash and dry the rice straw, crush it with a pulverizer, sieve it, and take 80-100 mesh rice straw powder for later use.
[0058] Rice straw powder and an aqueous ethanol solution were mixed at a solid-liquid ratio of 1g:(8-20)mL and placed in a closed reactor. The volume fraction of the aqueous ethanol solution was 60-80%. The mixture was heated at 160-240℃ for 2-3 hours. After the reaction, the mixture was filtered to obtain rice straw residue, which was then dried to obtain pretreated rice straw. In this example, 5g of rice straw powder and 60ml of aqueous ethanol solution were reacted at 200℃ for 3 hours, and the volume fraction of the aqueous ethanol solution was 70%. In other examples, the reaction temperature could be 160 or 240℃, the reaction time could be 2 hours, and the volume fraction of the aqueous ethanol solution could be 60 or 80%.
[0059] Pretreated rice straw and potassium hydroxide solution were mixed in a flask at a solid-liquid ratio of 1g:(17.5-22.5)ml. The ambient temperature was set at 85-95℃, and the mixture was stirred to react. After the reaction was completed, the alkali-treated rice straw solid was filtered out and mixed with a 4-6wt% hydrogen peroxide solution at a solid-liquid ratio of 1g:(90-110)ml. The mixture was heated and stirred at 65-75℃ for 1.5-2.5h to obtain rice straw-derived cellulose. In this embodiment, 2g of pretreated rice straw was mixed with 35-45mL of potassium hydroxide solution and added to the flask. The alkali-treated rice straw solid was then mixed with 180-220mL of 2wt% hydrogen peroxide solution. In other embodiments, the concentration of hydrogen peroxide solution could be 4 or 6wt%.
[0060] The preparation of rice straw-derived cellulose acetate (CA) includes the following steps:
[0061] Rice straw-derived cellulose was mixed with glacial acetic acid at a solid-liquid ratio of 1g:(14-18)ml. Concentrated sulfuric acid with a mass fraction of 98% was added as a catalyst, with the amount of concentrated sulfuric acid being 1-3% of the volume of glacial acetic acid. Acetic anhydride was then added, with a mass ratio of rice straw-derived cellulose to acetic anhydride of 1:(3-5). An acetylation reaction was carried out at 30-50℃ for 1-3 hours. After the reaction, distilled water was added to the acetylated solution to precipitate the precipitate. The mixture was then vacuum filtered and washed with deionized water until the filtrate was neutral. Finally, the filtered solid was freeze-dried to obtain rice straw-derived cellulose acetate. In this embodiment, 0.5g of rice straw-derived cellulose was mixed with 7-9mL of glacial acetic acid.
[0062] Hollow porous cellulose acetate fiber membrane (HPCAFM) was prepared using coaxial electrospinning and hydrothermal etching methods, including the following steps:
[0063] Preparation of coaxial electrospinning shell spinning solution: The coaxial electrospinning shell spinning solution contains three polymers: polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and rice straw-derived cellulose acetate (CA), with a mass ratio of PAN:PVP:CA = 1:(2.0-4.0):(3.0-5.0), and the total mass of the three polymers to the volume ratio of the solvent N,N-dimethylacetamide (DMAc) is (1.5-4.0):10 (g / mL);
[0064] Preparation of coaxial electrospinning core layer spinning solution: The coaxial electrospinning core layer spinning solution is a DMAc solution of polyvinylpyrrolidone (PVP) with a mass-to-volume ratio of (1.5-3.5):10 (g / mL);
[0065] In this embodiment, the coaxial electrospinning shell layer spinning solution can be prepared by adding 0.2g PAN, 0.5g PVP and 0.7g CA to 6mL DMAc and stirring to dissolve; the coaxial electrospinning core layer spinning solution can be prepared by adding 1.5g PVP to 6mL DMAc and stirring to dissolve.
[0066] At room temperature, with a positive voltage of 20kV and a negative voltage of 5kV, the spinning needle can be translated 0cm wide along the receiver direction, the distance between the spinning needle and the receiver is 16cm, and the spinning humidity is 60%. Coaxial electrospinning is performed by simultaneously pumping coaxial electrospinning shell layer spinning solution and coaxial electrospinning core layer spinning solution to obtain a nanofiber membrane; the nanofiber membrane is a core-shell structured nanofiber membrane. In other embodiments, the positive voltage can be 15 or 25kV, the negative voltage can be 4 or 6kV, the spinning needle can be translated 5cm wide along the receiver direction, the distance between the spinning needle and the receiver can be 14 or 18cm, and the spinning humidity can be 50% or 70%.
[0067] The nanofiber membrane was placed in a pressure-resistant container, and deionized water was added to ensure that the liquid-to-solid volume ratio was not less than 80 mL / g, thus ensuring that the nanofiber membrane was fully submerged. The container was then sealed and heat-treated at 110-130℃ for 2-4 hours to remove polyvinylpyrrolidone (PVP). After the reaction system was naturally cooled to room temperature, the reacted nanofiber membrane was removed, washed with deionized water until neutral, and finally freeze-dried to obtain HPCAFM.
[0068] The preparation of hollow porous cellulose acetate-derived carbon fiber membranes (HPCACM) includes the following steps:
[0069] HPCAFM is obtained by pre-oxidation in a muffle furnace and carbonization in a tube furnace;
[0070] The pre-oxidation in a muffle furnace includes: heating to 280°C at a rate of 1°C / min in air or an oxygen-containing atmosphere, maintaining the temperature, and reacting for 1 hour; in other embodiments, the temperature can be increased to 250°C or 300°C at a rate of 0.5°C or 2°C / min, and reacted for 0.5 or 2 hours.
[0071] Tubular furnace carbonization includes: heating to 600°C at a heating rate of 5°C / min under an inert atmosphere, maintaining the temperature, and reacting for 1 hour to obtain HPCACM; in other embodiments, the heating rate can be 2 or 10°C / min to 550 or 650°C, and the reaction can be carried out for 0.5 or 2 hours.
[0072] The preparation of HPCACM@Co3O4 composite material includes the following steps:
[0073] HPCACM carrier and Co(NO3)2·6H2O are dispersed in anhydrous ethanol at a mass molar ratio of 1g:(7.7-69.2)mmol, with the ethanol content controlled at 60-100mL per gram of carrier. The mixture is stirred for 1 hour (or 0.5 or 2 hours in other embodiments), then a certain amount of NH4HCO3 is added, and stirring continues for 6 hours (or 4 or 8 hours in other embodiments). The reactants are then removed and dried at 60-80℃ for 6-12 hours to obtain the precursor. The precursor is placed in a muffle furnace and heated to 300℃ at a programmed heating rate of 3℃ / min under air atmosphere. The temperature is maintained for 2 hours, and the mixture is calcined. After natural cooling, the HPCACM@Co3O4 composite material is obtained. In other embodiments, the temperature can be increased to 250 or 350℃ at a heating rate of 1 or 5℃ / min, and calcined for 1 or 3 hours.
[0074] Using the HPCACM carrier as a reference, the amount of Co(NO3)2·6H2O added was controlled so that the theoretical mass loading of cobalt in the composite material was 4.6%-41.4%; the molar ratio of Co(NO3)2·6H2O to NH4HCO3 was 1:(2.5-3.5); in this embodiment, 80 mL of anhydrous ethanol was used for every 13 mg of carrier, and then 0.5 mmol of Co(NO3)2·6H2O and 1.5 mmol of NH4HCO3 were added.
[0075] Example 2
[0076] This embodiment provides an HPCACM@Co3O4 composite material, which is obtained based on the preparation method of Example 1.
[0077] Example 3
[0078] This embodiment provides an application of the HPCACM@Co3O4 composite material, based on the composite material of Example 2, for the degradation of water pollutants; the composite material has a high specific surface area and a micro-mesoporous hierarchical structure, providing a rich active interface for catalytic reactions, which helps to promote the mass transfer between reactants and products and efficiently activate potassium persulfate.
[0079] The hollow porous cellulose acetate fiber membrane (HPCAFM), hollow porous cellulose acetate derived carbon fiber membrane (HPCACM), and HPCACM@Co3O4 composite material prepared in Example 1 were characterized in terms of morphology and structure. The surface morphology and elemental distribution of the materials were observed using a TESCAN-MAIA3 field emission scanning electron microscope. The microstructure of the materials was then characterized using a JEOL JEM 2100F high-resolution transmission electron microscope. The results are as follows: Figure 1-6 As shown:
[0080] The hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM) and HPCACM@Co3O4 composite material prepared in Example 1, as well as Co3O4, were characterized by X-ray diffraction (XRD). The XRD patterns of the materials were measured using an XRD-7000 X-ray diffractometer manufactured by Shimadzu Corporation of Shanghai, and the crystal structure of the materials was analyzed by referring to standard cards. The test conditions were set as follows: X-ray target source: Cu-Kα; operating voltage: 40.0 kV; scanning range: 5° to 80°; scanning speed: 5° / min. The results are as follows: Figure 7 As shown
[0081] The hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM) and HPCACM@Co3O4 composite material prepared in Example 1, as well as Co3O4, were characterized for specific surface area and pore size distribution. Nitrogen adsorption-desorption tests were performed using a JW-BK100 surface area analyzer to detect the specific surface area, pore volume (total pore volume), and pore size (pore size) distribution. N2 was used as the protective gas during degassing, and the temperature was set to 90℃. The results are as follows: Figure 8 And as shown in Table 1:
[0082] Table 1. Distribution results of specific surface area, pore volume (total pore volume), and pore size (pore size).
[0083] sample <![CDATA[Specific surface area (m 2 g -1 )]]> Average porosity (nm) <![CDATA[Total pore volume (cm 3 g -1 )]]> HPCACM 415.6 5.301 0.5 <![CDATA[Co3O4]]> 52.1 34.123 0.473 <![CDATA[HPCACM@Co3O4]]> 257.2 7.84 0.49
[0084] Analysis of the nitrogen adsorption-desorption test results shows that HPCACM, HPCACM@Co3O4, and Co3O4 all exhibit typical Type IV isotherms accompanied by H4-type hysteresis loops, indicating that they all possess mesoporous structure characteristics. Among them, HPCACM exhibits the highest specific surface area (415.6 m²). 2 The isotherm of this material ( / g) rises sharply in the low-pressure region, combined with a sharp peak at 1.5 nm and a broad peak at 2-10 nm in the pore size distribution diagram, confirming that it is a hierarchical porous carbon material with numerous micropores and mesopores. After loading Co3O4 onto its surface to form the HPCACM@Co3O4 composite material, the specific surface area decreases to 257.2 m². 2 / g, while the pore size distribution showed a significant decrease in peak intensity for micropores smaller than 2nm and small mesopores of 2-5nm, directly proving that Co3O4 nanoparticles successfully loaded and partially blocked the micropores and smaller mesopores in the carbon substrate, leading to a decrease in specific surface area and pore volume. In contrast, pure-phase Co3O4 had the lowest specific surface area (52.1 nm). 2The adsorption capacity of Co3O4 nanoparticles in the low-pressure region of its isotherm is small, and the pore size distribution is concentrated in the range of 10-30 nm, indicating that it is a mesoporous metal oxide formed by the accumulation of nanoparticles and is almost free of micropores. In summary, this study successfully loaded and highly dispersed Co3O4 nanoparticles on a hierarchical porous carbon substrate. The composite material not only inherits the advantages of high specific surface area of carbon support, providing a rich active interface for catalytic reactions, but its unique micro-mesoporous hierarchical structure also helps to promote the mass transfer between reactants and products. This structure effectively prevents the aggregation of Co3O4, fully exposes the active sites, and allows Co3O4 to give full play to its advantages in the process of activating permonosulfate (PMS) to generate free radicals, showing catalytic potential superior to pure phase Co3O4.
[0085] Catalytic Degradation Experiment: Tetracycline (TC) was used as the target pollutant, and the catalytic activity of the HPCACM@Co3O4 composite material was evaluated by PMS activation. The catalytic degradation experiment was conducted in a continuously stirred 100 mL beaker at room temperature with a stirring speed of 100 rpm. First, the catalyst was added to 50 mL of a 20 mg / L TC solution and stirred for 30 min to reach adsorption-desorption equilibrium. Then, 20 mg of PMS was added to initiate the catalytic degradation reaction. At 0, 2, 4, 8, 12, 16, 20, 25, and 30 min, 1.9 mL of sample solution was taken and placed in a centrifuge tube containing 0.1 mL of 0.1 mol / L sodium thiosulfate to terminate the reaction. After centrifugation and filtration through a 0.45 μm microporous membrane, the TC concentration in the supernatant was detected at 356 nm using a UV-Vis spectrophotometer. The results are shown below. Figure 9 As shown, in the experiment: [Catalyst] = 0.15 g / L, [PMS] = 0.4 g / L, pH = 6.04.
[0086] Figure 9The degradation efficiency of TC in seven different systems was compared. TC showed virtually no degradation in systems containing only HPCACM, HPCACM@Co3O4, or Co3O4, while PMS alone achieved approximately 20% TC removal within 30 minutes, indicating that PMS possesses a certain oxidizing capacity. In the HPCACM+PMS system, the TC degradation rate was improved, suggesting that HPCACM material has a certain PMS activation ability. The Co3O4+PMS system further improved the degradation efficiency, demonstrating the effective activation of PMS by Co3O4. Notably, the HPCACM@Co3O4+PMS system exhibited the best catalytic performance, with a significantly higher TC degradation rate within 30 minutes compared to other systems, indicating that the composite material HPCACM@Co3O4 has excellent synergistic catalytic effect. All degradation processes conformed to a pseudo-first-order kinetic model, with the HPCACM@Co3O4+PMS system exhibiting the highest reaction rate constant, significantly superior to the single-component systems. The improved catalytic performance of the composite material may be attributed to the following reasons: (i) the hollow porous structure of HPCACM promotes mass transfer and adsorption of reactants; (ii) the uniform dispersion of Co3O4 nanoparticles on the support increases the number of active sites; and (iii) the interfacial interaction between the support and the metal oxide enhances the activation efficiency of PMS, thereby accelerating the degradation of TC.
[0087] Experiment exploring influencing factors:
[0088] The effect of Co salt dosage was investigated by using HPCACM@Co3O4 samples with different loadings for catalytic degradation experiments. Other reaction conditions and operation steps 1.4 were consistent.
[0089] The effect of catalyst dosage was investigated by varying the catalyst dosage in the reaction system (0.05, 0.10, 0.15, and 0.20 g / L), while other reaction conditions remained consistent with the catalytic degradation experiment.
[0090] Effect of PMS concentration: The PMS concentration in the reaction system was changed (0.2, 0.4 and 0.6 g / L), while other reaction conditions were consistent with the catalytic degradation experiment;
[0091] The effect of solution pH was investigated. Before adding the catalyst, the initial pH of the reaction solution was adjusted using 0.2 M H₂SO₄ or NaOH (3, 9, and 11). Other reaction conditions were consistent with the catalytic degradation experiments.
[0092] Effect of inorganic salt ions: Before adding the catalyst, different concentrations of NaCl, NaHCO3 and NaH2PO4 (5, 10 and 20 mM) were added to the reaction system, and other reaction conditions were the same as those in the catalytic degradation experiment.
[0093] The effect of organic matter was investigated by adding different concentrations of HA (2, 4 and 6 mg / L) to the reaction system before adding the catalyst, while other reaction conditions remained the same as in the catalytic degradation experiment.
[0094] The results are as follows Figure 10 As shown in the graph of the effect of Co3O4 loading, as the loading increases from 0.1 mmol to 0.9 mmol, both the degradation efficiency and the reaction rate k value show a trend of first increasing and then decreasing, reaching the optimal performance at 0.5 mmol (k = 0.0926 min). -1 This indicates that an appropriate catalyst loading can effectively expose active sites, while excessive loading may lead to particle agglomeration and reduce catalytic activity. Different catalyst dosages (0.05, 0.10, 0.15, and 0.20 g / L) have a significant impact on pollutant degradation. As the catalyst dosage increases from 0.05 g / L to 0.15 g / L, the degradation efficiency gradually improves, reaching its optimal performance at 0.15 g / L. This suggests that appropriately increasing the catalyst dosage helps expose more active sites and promotes PMS activation. However, when the catalyst dosage is further increased to 0.20 g / L, the degradation efficiency does not continue to improve but instead decreases slightly. This may be because excessive catalyst may trigger free radical quenching, inhibiting the reaction. Therefore, 0.15 g / L is the optimal catalyst dosage in this system, at which point the catalyst surface has sufficient active sites for efficient PMS activation. PMS concentration directly affects the amount of active species generated in the reaction system, thus determining the degradation efficiency of the target pollutant. As the PMS concentration increased from 0.2 g / L to 0.4 g / L, the pollutant degradation rate increased significantly, and the reaction rate constant k also increased accordingly, indicating that more PMS molecules were activated to generate free radicals or non-free radical active species, thereby accelerating the reaction process. However, when the PMS concentration further increased to 0.6 g / L, the degradation efficiency did not continue to improve; instead, it decreased to some extent. This may be because excess PMS acts as a free radical (such as SO4· ... - The PMS quencher consumes the already generated active species, thereby inhibiting the degradation reaction. Therefore, the optimal dosage concentration of PMS in this system is 0.4 g / L. The initial solution pH is a key factor affecting the catalytic degradation process, as it can alter the speciation and surface charge state of the pollutants and PMS. The degradation performance of the reaction system was evaluated within a pH range of 3 to 11, with the best catalytic activity observed at pH = 6.04, resulting in a corresponding rate constant k of 0.0905 min⁻¹. -1 Within a near-neutral pH range (approximately 6-9), the system maintained high degradation efficiency, indicating that the catalyst possesses good pH adaptability. However, under strong acid (pH=3) or strong base (pH=11) conditions, the degradation performance was inhibited, with the k value decreasing to 0.0693 min, respectively. -1With 0.048min -1 Possible causes of this phenomenon include: in an acidic environment, excessive H+... + It can quench SO4· - Co3O4 reacts with free radicals such as ·OH; however, under alkaline conditions, the active sites of Co3O4 readily react with OH radicals. - The formation of a hydroxide coating reduces surface reactivity, thus affecting the activation efficiency of PMS. Therefore, this catalytic system exhibits optimal degradation performance under near-neutral conditions.
[0095] In real-world aquatic environments, various inorganic anions and natural organic compounds are often present, which may significantly influence the catalytic degradation process. Therefore, this study evaluated the role of Cl... - HCO3 - H2PO4 - The effects of three common inorganic ions and humic acid (HA) at different concentrations on the degradation behavior of pollutants. Results are as follows: Figure 11 As shown, Cl - The addition of Cl showed a certain inhibitory effect on the degradation process, and with the increase of Cl... - As the concentration increased from 5 mM to 20 mM, the pollutant degradation efficiency gradually decreased, and the reaction rate constant k value also decreased accordingly, indicating that Cl... - The reaction system exhibits a concentration-dependent inhibitory effect, which may be due to Cl. - Will be with SO4· - It reacts with reactive free radicals such as ·OH, thereby weakening its overall oxidizing capacity; HCO3 - The reaction also exhibited an inhibitory effect; as the concentration increased from 5 mM to 20 mM, the pollutant degradation efficiency gradually decreased, and the reaction rate constant k also decreased from 0.0495 min. -1 Reduced to 0.0364 min -1 This indicates that HCO3 - This hindered the catalytic reaction to some extent, possibly because of HCO3. - It will quench SO4· in the system - It reacts with ·OH to convert it into a less oxidizing carbonate radical (CO3· OH). - This leads to a decrease in the degradation efficiency of the target pollutant; H2PO4 - It showed a slight promoting effect on the reaction system; with increasing concentration, both the pollutant degradation rate and the k-value increased slightly, indicating that H2PO4 exhibited a slight promoting effect on the reaction system. -To a certain extent, it can participate in the PMS activation process, promoting the generation of reactive oxide species and thus enhancing pollutant degradation. Furthermore, humic acid (HA), as a representative of natural organic matter, has a significant inhibitory effect on the catalytic degradation process. As the HA concentration increases from 2 mg / L to 6 mg / L, the pollutant degradation efficiency gradually decreases, and the k value decreases from 0.0693 min... -1 It dropped to 0.0586 min. -1 This is mainly due to the phenolic hydroxyl and carboxyl functional groups abundant in the HA molecule structure. On the one hand, these functional groups can compete with the target pollutants for active free radicals, and on the other hand, they may cover the active sites on the catalyst surface, thereby hindering the catalytic reaction.
[0096] Long-term stability experiment: Cyclic experiment. After the catalytic degradation reaction was completed, the used catalyst was taken out, washed three times with deionized water, dried at 60°C, and reused in the next cycle experiment. A total of three cycles were conducted. The catalyst before and after the three cycles was characterized by X-ray diffraction (XRD). The XRD pattern and TC degradation results are shown below. Figure 12 As shown.
Claims
1. A method for preparing HPCACM@Co3O4 composite material, characterized in that, Includes the following steps: Preparation of rice straw-derived cellulose; Preparation of rice straw-derived cellulose acetate; Preparation of hollow porous cellulose acetate fiber membranes; Preparation of hollow porous cellulose acetate-derived carbon fiber membranes; Prepare HPCACM@Co3O4 composite material.
2. The method for preparing an HPCACM@Co3O4 composite material according to claim 1, characterized in that, The preparation of rice straw-derived cellulose includes the following steps: Wash and dry the rice straw, then crush it with a pulverizer, sieve it, and take 80-100 mesh rice straw powder for later use. The rice straw powder and the aqueous ethanol solution were mixed at a solid-liquid ratio of 1g:(8-20)mL, placed in a closed reactor, and heated to react. After the reaction was completed, the mixture was filtered to obtain rice straw residue, which was then dried to obtain pretreated rice straw. The pretreated rice straw and potassium hydroxide solution were mixed in a certain proportion and added to a flask. The ambient temperature was set at 85-95℃, and the mixture was stirred to react. After the reaction was completed, the alkali-treated rice straw solid was filtered out and mixed with a 4-6 wt% hydrogen peroxide solution at a solid-liquid ratio of 1 g:(90-110) ml. The mixture was heated and stirred at 65-75℃ for 1.5-2.5 h to obtain the rice straw-derived cellulose. The preparation of rice straw-derived cellulose acetate includes the following steps: The rice straw-derived cellulose was mixed with glacial acetic acid, and 98% concentrated sulfuric acid was added as a catalyst. Acetic anhydride was then added, and an acetylation reaction was carried out at 30-50°C for 1-3 hours. After the reaction was completed, distilled water was added to the acetylated solution to precipitate the cellulose. The solution was then vacuum filtered and washed with deionized water until the filtrate was neutral. Finally, the filtered solid was freeze-dried to obtain the rice straw-derived cellulose acetate.
3. The method for preparing an HPCACM@Co3O4 composite material according to claim 1, characterized in that, The preparation of the hollow porous cellulose acetate fiber membrane, using coaxial electrospinning and hydrothermal etching, includes the following steps: Preparation of coaxial electrospinning shell spinning solution: The coaxial electrospinning shell spinning solution contains three polymers: polyacrylonitrile (PAN), polyvinylpyrrolidone (PVP), and rice straw-derived cellulose acetate (CA), with a mass ratio of PAN:PVP:CA = 1:(2.0-4.0):(3.0-5.0), and the total mass of the three polymers to the volume ratio of the solvent N,N-dimethylacetamide (DMAc) is (1.5-4.0):10 (g / mL); Preparation of coaxial electrospinning core layer spinning solution: The coaxial electrospinning core layer spinning solution is a DMAc solution of polyvinylpyrrolidone (PVP) with a mass-to-volume ratio of (1.5-3.5):10 (g / mL). At room temperature, with a positive voltage of 15-25kV and a negative voltage of 4-6kV, the spinning needle can be translated 0-5cm along the receiver direction. The distance between the spinning needle and the receiver is 14-18cm, and the spinning humidity is 50%-70%. Through the coaxial electrospinning method, the coaxial electrospinning shell layer spinning solution and the coaxial electrospinning core layer spinning solution are simultaneously pumped to perform spinning, thereby obtaining a nanofiber membrane; the nanofiber membrane is a core-shell structured nanofiber membrane. The nanofiber membrane was placed in a pressure-resistant container, and deionized water was added to ensure that the liquid-to-solid volume ratio was not less than 80 mL / g, thus ensuring that the nanofiber membrane was fully submerged. The container was then sealed and heat-treated at 110-130°C for 2-4 hours to remove polyvinylpyrrolidone (PVP). After the reaction system was naturally cooled to room temperature, the reacted nanofiber membrane was removed, washed with deionized water until neutral, and finally freeze-dried to obtain the HPCAFM.
4. The method for preparing an HPCACM@Co3O4 composite material according to claim 1, characterized in that, The preparation of the hollow porous cellulose acetate-derived carbon fiber membrane (HPCACM) includes the following steps: HPCAFM was pre-oxidized in a muffle furnace and carbonized in a tubular furnace to obtain HPCACM; The muffle furnace pre-oxidation includes: heating to 250-300°C in air or an oxygen-containing atmosphere at a heating rate of 0.5-2°C / min, maintaining the temperature, and reacting for 0.5-2 hours; The tubular furnace carbonization process includes: heating to 550-650°C at a rate of 2-10°C / min under an inert atmosphere, maintaining the temperature, and reacting for 0.5-2 hours to obtain the HPCACM.
5. The method for preparing an HPCACM@Co3O4 composite material according to claim 1, characterized in that, The preparation of the HPCACM@Co3O4 composite material includes the following steps: The HPCACM carrier and Co(NO3)2·6H2O are dispersed in anhydrous ethanol at a certain mass molar ratio, with the amount of ethanol controlled at 60-100 mL per gram of carrier. The mixture is stirred for 0.5-2 h, and then a certain amount of NH4HCO3 is added. The mixture is stirred for another 4-8 h. The reactants are then removed and dried at 60-80 °C for 6-12 h to obtain the precursor. The precursor is placed in a muffle furnace and heated to 250-350 °C at a programmed heating rate of 1-5 °C / min under an air atmosphere. The temperature is maintained and calcined for 1-3 h. After natural cooling, the HPCACM@Co3O4 composite material is obtained.
6. The method for preparing an HPCACM@Co3O4 composite material according to claim 2, characterized in that, The volume fraction of the aqueous ethanol solution is 60-80%, the pretreated rice straw and potassium hydroxide solution are mixed at a solid-liquid ratio of 1g:(17.5-22.5)ml, the concentration of the potassium hydroxide solution is 4-6wt%, the heating reaction temperature is 160-240℃, and the reaction time is 2-3h.
7. The method for preparing an HPCACM@Co3O4 composite material according to claim 2, characterized in that, The rice straw-derived cellulose and glacial acetic acid are mixed at a solid-liquid ratio of 1g:(14-18)ml, the amount of concentrated sulfuric acid used is 1-3% of the volume of glacial acetic acid, and the mass ratio of the rice straw-derived cellulose to the acetic anhydride is 1:(3-5).
8. The method for preparing an HPCACM@Co3O4 composite material according to claim 5, characterized in that, The HPCACM and Co(NO3)2·6H2O are dispersed in anhydrous ethanol at a mass molar ratio of 1g:(7.7-69.2)mmol; the amount of Co(NO3)2·6H2O added is controlled based on the HPCACM carrier so that the theoretical mass loading of cobalt in the composite material is 4.6%-41.4%; the molar ratio of Co(NO3)2·6H2O to NH4HCO3 is 1:(2.5-3.5).
9. An HPCACM@Co3O4 composite material, characterized in that, It is obtained based on the preparation method according to any one of claims 1-8.
10. An application of an HPCACM@Co3O4 composite material, based on the composite material of claim 9, for the degradation of water pollutants; the composite material has a high specific surface area and a micro-mesoporous hierarchical structure, providing abundant active interfaces for catalytic reactions, which helps to promote mass transfer between reactants and products and efficiently activate potassium persulfate.