A batch preparation method of cobalt-based heterojunction catalyst, cobalt-based heterojunction catalyst and application thereof

Abstract

This invention relates to a method for the batch preparation of cobalt-based heterojunction catalysts, the cobalt-based heterojunction catalysts themselves, and their applications. The invention utilizes a green, environmentally friendly, and simple ball milling and calcination method to prepare cobalt-based heterojunction catalysts. This batch preparation method avoids organic solvent pollution, is low-cost, and environmentally friendly. The prepared cobalt-based heterojunction catalysts exhibit high specific surface area and uniform metal site dispersion, enhance catalytic degradation activity against various pollutants in water treatment, and demonstrate good cycle stability, making them suitable for industrial wastewater treatment.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation and water treatment, specifically relating to a method for batch preparation of cobalt-based heterojunction catalysts, cobalt-based heterojunction catalysts and their applications. Background Technology

[0002] In recent years, water pollution caused by persistent micropollutants has become a hot topic of concern for the international community and the scientific community. Sulfamethoxazole (SMX), a widely used sulfonamide antibiotic, exhibits strong environmental stability and is difficult to degrade naturally. It enters the environment through medical, aquaculture, and domestic wastewater, inhibiting the growth of aquatic organisms even at low concentrations, and its long-term accumulation may affect human health through the food chain. Traditional wastewater treatment methods such as biological treatment, adsorption, and ozone oxidation are inefficient and costly in degrading structurally stable pollutants like SMX, failing to meet treatment requirements. Therefore, developing more effective removal technologies and utilizing green energy is a crucial issue in the current environmental protection field.

[0003] Among numerous wastewater treatment technologies, advanced oxidation technologies (AORs) are widely used for the removal of various organic pollutants due to their advantages such as strong oxidizing power, mild reaction conditions, excellent removal effect, and short reaction cycle. Among these, AORs using peroxymonosulfate (PMS) as the oxidant have received extensive research and application due to their good water solubility, convenient storage and transportation, and outstanding oxidizing power. However, PMS itself has a relatively weak ability to oxidize organic pollutants and requires activation by external substances or energy to generate highly oxidizing free radicals in order to achieve efficient degradation of organic pollutants. Currently, mainstream catalysts include transition metal salts and their oxides in homogeneous systems, as well as composite salts in heterogeneous systems. However, these catalysts generally suffer from narrow pH application ranges, easy loss from the reaction system, and significant metal leaching, which can easily lead to secondary pollution, limiting their practical application scenarios.

[0004] Heterojunction catalysts exhibit significant advantages in advanced oxidation technologies due to their unique interfacial structure and electronic properties: they enhance redox performance through synergistic effects of metal sites and electron transfer channels, significantly improving the efficiency of active species generation and pollutant degradation rates, while inhibiting charge recombination to extend free radical lifetime; they possess both strong stability and excellent cycling performance, effectively reducing the risk of metal leaching, and can maintain activity over a wide pH range, making them suitable for complex wastewater qualities; they have broad-spectrum degradation capabilities, enabling the simultaneous degradation or complete mineralization of various persistent micropollutants, and can reduce energy consumption by lowering reaction activation energy. Combined with a simple and easily scalable preparation process, they significantly reduce industrial application costs, making them the preferred catalytic system for the efficient treatment of recalcitrant pollutants.

[0005] In summary, the existing technology has the following shortcomings:

[0006] 1. Defects in synthesis methods: Traditional cobalt-based mixture synthesis relies on solvothermal methods, template methods, etc., which require a large amount of organic solvents or high-temperature and high-pressure equipment, resulting in high production costs and poor environmental performance, and cannot meet the needs of large-scale production; existing heterostructure construction processes are complex, and the metal sites are unevenly dispersed, making it difficult to form a stable synergistic effect, which affects the stability of catalytic performance and batch reproducibility.

[0007] 2. Catalytic performance defects: Existing cobalt-based catalysts have low degradation efficiency for various pollutants in water treatment (such as organic dyes and chlorine-containing compounds), especially under low temperature or room temperature conditions, which results in insufficient activity and requires additional energy consumption; heterogeneous cobalt-based catalysts have limited specific surface area, insufficient exposure of active sites, and easy loss of metal, resulting in short service life and high risk of secondary pollution.

[0008] 3. Application adaptability deficiency: Existing cobalt-based catalytic mixtures lack specific designs for water treatment scenarios, making it difficult to balance the needs of batch preparation with high-efficiency degradation performance, and thus failing to meet the actual application scenarios of industrial wastewater treatment. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] To address the problems of poor activity of existing cobalt-based catalysts in degrading persistent micropollutants and the complexity and difficulty in mass production of heterojunction structures, this invention provides a method for mass production of cobalt-based heterojunction catalysts, the cobalt-based heterojunction catalyst itself, and its applications. This mass production method utilizes a green and simple ball milling process, avoiding organic solvent pollution, and is low-cost and environmentally friendly. The prepared cobalt-based heterojunction catalyst exhibits high specific surface area, uniform metal site dispersion, enhanced catalytic degradation activity against various pollutants in water treatment, and good cycle stability, making it suitable for industrial wastewater treatment.

[0011] Solution for solving the problem

[0012] [1] A method for batch preparation of a cobalt-based heterojunction catalyst, comprising the following steps:

[0013] The salts of metal M and cobalt salts were mechanically ball-milled to obtain a mixture;

[0014] The mixture was calcined in air to obtain a MO-Co3O4 cobalt-based heterojunction catalyst.

[0015] Wherein, M is one or both of Cu and Zn;

[0016] The mass ratio of the salt of metal M to the cobalt salt is (1~50):1.

[0017] [2] According to the batch preparation method described in [1],

[0018] The salt of metal M is an acetate of metal M;

[0019] The cobalt salt is a cobalt acetate.

[0020] [3] According to the batch preparation method described in [1] or [2],

[0021] The ball-to-material ratio of the mechanical ball mill is (40~80):1; and / or,

[0022] The conditions for the mechanical ball milling are: a ball milling speed of 100-600 rpm, a ball milling time of 1-10 hours, and a ball milling mode of forward rotation, reverse rotation, or alternating forward and reverse rotation.

[0023] [4] According to the batch preparation method described in [3],

[0024] The ball milling mode is to rotate forward for 30 minutes and then stop for 5-10 minutes, then rotate backward for 30 minutes and then stop for 5-10 minutes, repeating the cycle 1-10 times.

[0025] [5] The batch preparation method according to any one of [1]-[4],

[0026] The calcination temperature is 400-800℃, the heating rate is 1-5℃ / min, and the calcination time is 2-4 h.

[0027] [6] A cobalt-based heterojunction catalyst, which is obtained by any one of the batch preparation methods described in [1]-[5].

[0028] [7] An application of a cobalt-based heterojunction catalyst prepared by any one of [1]-[5] in batch preparation or a cobalt-based heterojunction catalyst according to [6] for water treatment.

[0029] The cobalt-based heterojunction catalyst is used to decompose oxidants to generate reactive oxygen species to degrade pollutants in water.

[0030] [8] Based on the application described in [7],

[0031] The active oxygen species are selected from one or more of sulfate radicals, hydroxyl radicals, singlet oxygen, and high-valence metal oxygen species.

[0032] [9] According to the application described in [7] or [8],

[0033] The oxidant is selected from one or more of ozone, hydrogen peroxide, and persulfate.

[0034]

[10] According to the application described in [9],

[0035] The oxidant is persulfate, and the concentration of persulfate is 0.1~1.25 mM; and / or,

[0036] The dosage of the cobalt-based heterojunction catalyst is 0.05~5.0 g / L.

[0037] The effects of the invention

[0038] 1. This invention utilizes a green, environmentally friendly, and simple ball milling and calcination method to prepare cobalt-based heterojunction catalysts. During the preparation process, cobalt salts are selected, and different metal salts such as Cu and Zn are added during ball milling to create a good synergistic effect between metal atoms, increasing their functional diversity. This batch preparation method is simple to operate, low in cost, avoids organic solvent pollution, reduces the risk of secondary pollution, is environmentally friendly, and can realize the large-scale synthesis of cobalt-based heterojunction mixtures.

[0039] 2. The cobalt-based heterojunction catalyst prepared by this invention has the characteristics of high specific surface area and uniform metal site dispersion. The larger specific surface area provides more reactive sites, which greatly improves the migration rate of oxygen species and significantly enhances the catalytic degradation activity of various pollutants (such as sulfamethoxazole or bisphenol A) in water treatment. At the same time, it improves the stability and recycling performance of the catalyst. Attached Figure Description

[0040] Figure 1 The image shows a transmission electron microscope (TEM) image of the Co-Cu heterojunction catalyst prepared in Example 1.

[0041] Figure 2 The X-ray photoelectron spectroscopy (XPS) spectrum of the Co-Cu heterojunction catalyst prepared in Example 1;

[0042] Figure 3 X-ray diffraction (XRD) patterns of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2;

[0043] Figure 4 X-ray diffraction (XRD) patterns of the catalysts prepared in Example 6, Comparative Example 3, and Comparative Example 4;

[0044] Figure 5 The graph shows the degradation effect of the Co-Cu heterojunction catalyst prepared in Examples 1-5 on the hydrogen persulfate system for sulfamethoxazole.

[0045] Figure 6 The degradation effect of the catalyst-activated hydrogen persulfate system prepared in Examples 1, 1, 2, 1 and 2 on sulfamethoxazole is shown in the figure.

[0046] Figure 7 The degradation effect of the catalyst-activated hydrogen persulfate system prepared in Example 6, Comparative Example 3, and Comparative Example 4 on bisphenol A is shown in the figure.

[0047] Figure 8 The attached figures show the nitrogen adsorption-desorption of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0048] Figure 9 The pore size distribution diagrams are for the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2.

[0049] Figure 10 The graph shows the removal rate of sulfamethoxazole in the Co-Cu heterojunction catalyst activated by Example 1 for 12 hours. Detailed Implementation

[0050] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below. The term "exemplary" as used herein means "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as superior to or better than other embodiments.

[0051] Furthermore, to better illustrate the present invention, numerous specific details are set forth in the following detailed embodiments. Those skilled in the art should understand that the present invention can be practiced without certain specific details. In other instances, methods, means, apparatus, and steps well known to those skilled in the art have not been described in detail in order to highlight the spirit of the present invention.

[0052] Unless otherwise stated, all units used in this specification are international standard units, and all numerical values ​​and ranges appearing in this invention should be understood to include systematic errors that are unavoidable in industrial production.

[0053] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0054] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0055] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0056] The core of this invention lies in the fact that cobalt-based heterojunction catalysts can be prepared in large quantities through ball milling and calcination.

[0057] Specifically, the present invention provides a method for the batch preparation of a cobalt-based heterojunction catalyst, which includes the following steps:

[0058] The salts of metal M and cobalt salts were mechanically ball-milled to obtain a mixture;

[0059] The mixture was calcined in air to obtain a MO-Co3O4 cobalt-based heterojunction catalyst.

[0060] Where M is one or both of Cu and Zn;

[0061] The mass ratio of the salt of metal M to the cobalt salt is (1~50):1.

[0062] In this invention, the mass ratio of the salt of metal M to the cobalt salt is (1~50):1, preferably (4~20):1, for example, it can be 1:1, 3:2, 4:1, 5:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, etc. When the content of cobalt salt is low (e.g., the mass ratio of the salt of metal M to the cobalt salt is 50:1), due to insufficient core active sites, the bimetallic synergy and lattice defects are weakened, resulting in poor PMS activation and pollutant degradation effects. When the content of cobalt salt is high (e.g., the mass ratio of the salt of metal M to the cobalt salt is 3:2), due to the excessive proportion of cobalt salt, cobalt oxide is prone to abnormal grain growth and agglomeration during high-temperature calcination, resulting in a sharp decrease in specific surface area. A large number of active sites are wrapped and covered, which reduces the effective contact area, and the catalytic activity decreases instead of increasing.

[0063] In this invention, the salt of metal M can be an acetate of metal M.

[0064] In this invention, the cobalt salt is a cobalt acetate.

[0065] In this invention, the ball-to-material ratio of the mechanical ball mill is (40~80):1, for example, it can be 50:1, 60:1, 70:1, etc.

[0066] In this invention, the conditions for mechanical ball milling are as follows: the ball milling speed is 100~600 rpm, for example, 200 rpm, 300 rpm, 400 rpm, 500 rpm, etc.; the ball milling time is 1~10 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, 310 minutes, 6 hours, 7 hours, 8 hours, 9 hours, etc.; the ball milling mode is forward rotation, reverse rotation, or alternating forward and reverse rotation, preferably alternating forward and reverse rotation.

[0067] In some embodiments of the present invention, the ball milling mode is to rotate forward for 30 minutes and then stop for 5-10 minutes, rotate backward for 30 minutes and then stop for 5-10 minutes, and repeat 1-10 times.

[0068] In this invention, when the reaction raw materials are copper acetate and cobalt acetate, the mechanical ball milling conditions can be as follows: ball milling time is 5 hours, rotating forward for 30 minutes and stopping for 5 minutes, rotating backward for 30 minutes and stopping for 5 minutes, repeating 5 times, and the ball milling speed is 500 r / min.

[0069] In this invention, when the reaction raw materials are zinc acetate and cobalt acetate, the mechanical ball milling conditions can be as follows: ball milling time is 4 hours, rotating forward for 30 minutes and stopping for 10 minutes, rotating backward for 30 minutes and stopping for 10 minutes, repeating 4 times, and the ball milling speed is 400 r / min.

[0070] In this invention, there are no special limitations on the type, model, material of the grinding jar and grinding balls of the ball mill; any material that can achieve the technical effects described in this invention is acceptable.

[0071] In this invention, calcination can be carried out in a muffle furnace. The calcination temperature is 400-800℃, for example, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, etc.; the heating rate is 1-5℃ / min, for example, 1.5℃ / min, 2℃ / min, 2.5℃ / min, 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min, etc.; the calcination time is 2-4h, for example, 2.5h, 3h, 3.5h, etc.

[0072] Traditional single-metal oxide catalysts have a single active site and suffer from an inherent contradiction of "high activity - low stability": highly active metals (such as Co) are easily dissolved and their structures are prone to collapse, while low-active metals (such as ZnO) have extremely low catalytic efficiency. In contrast, the catalyst prepared in this invention forms a heterojunction structure, not a simple physical mixture. The two metal oxides form a highly uniformly dispersed composite phase structure with no obvious phase separation or metal agglomeration, and the active sites are fully exposed. This cobalt-based heterojunction catalyst features a high specific surface area and uniformly dispersed metal sites, enhancing the synergistic effect between metal atoms.

[0073] The present invention also provides a cobalt-based heterojunction catalyst, which is obtained by the aforementioned batch preparation method.

[0074] The present invention also provides a cobalt-based heterojunction catalyst obtained by the aforementioned batch preparation method or an application of the aforementioned cobalt-based heterojunction catalyst for water treatment, wherein the cobalt-based heterojunction catalyst is used to decompose oxidants to generate active oxygen species to degrade pollutants in water.

[0075] In this invention, the active oxygen species are selected from one or more of sulfate radicals, hydroxyl radicals, singlet oxygen, and high-valence metal oxygen species.

[0076] In this invention, the oxidant is selected from one or more of ozone, hydrogen peroxide, and persulfate, preferably peroxymonosulfate.

[0077] In this invention, the cobalt-based heterojunction catalyst can activate peroxymonosulfate (such as potassium peroxymonosulfate) to generate free radicals and / or non-free radical reactive oxygen species to degrade pollutants in water.

[0078] In some embodiments of the present invention, the oxidant is peroxymonosulfate, and the concentration of the peroxymonosulfate is 0.1~1.25 mM, for example, 0.2 mM, 0.5 mM, 0.8 mM, 1.0 mM, 1.2 mM, etc.

[0079] In this invention, the dosage of the cobalt-based heterojunction catalyst is 0.05~5.0 g / L, for example, it can be 0.08 g / L, 0.1 g / L, 0.12 g / L, 0.15 g / L, 0.2 g / L, 0.25 g / L, 0.5 g / L, 1.0 g / L, 2.0 g / L, 3.0 g / L, 4.0 g / L, etc.

[0080] In this invention, the water includes drinking water or organic wastewater; further, the organic wastewater includes one or more of the following: pharmaceutical wastewater, printing and dyeing wastewater, petrochemical wastewater, and papermaking wastewater.

[0081] Example

[0082] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0083] Example 1

[0084] 4 g of copper acetate and 1 g of cobalt acetate were placed in an agate ball mill jar. Then, 200 g of agate balls of different diameters (Φ) (Φ 5 mm: Φ 10 mm in a mass ratio of 1:1) were added to the jar. The mill was operated at 500 rpm, rotating clockwise for 30 min and stopping for 5 min, then rotating counterclockwise for 30 min and stopping for 5 min, repeating this cycle 5 times. After milling for 5 h, mixture A was obtained. Mixture A was placed in a muffle furnace and heated to 500 °C at a rate of 2 °C / min under air atmosphere, and calcined for 3 h to obtain a Co-Cu heterojunction catalyst (CuO-Co3O4).

[0085] Examples 2-5

[0086] Following the preparation method of Example 1, the mass ratio of copper acetate to cobalt acetate was changed to 3:2, 10:1, 20:1 and 50:1 respectively, while the other steps were the same, to prepare Co-Cu heterojunction catalyst (CuO-Co3O4).

[0087] Example 6

[0088] 1 g of cobalt acetate and 1 g of zinc acetate were placed in a stainless steel ball mill jar. Then, 100 g of agate balls of different diameters (Φ) (Φ 5 mm: Φ 10 mm mass ratio of 1:1) were added to the jar, resulting in a ball-to-material ratio of 50:1. The milling speed was 400 rpm, with the mill running forward for 30 min and then stopping for 10 min, followed by reverse rotation for 30 min and then stopping for 10 min, repeated 4 times. After milling for 4 h, mixture B was obtained. Mixture B was placed in a muffle furnace and heated to 500 °C at a rate of 2 °C / min under air atmosphere, and calcined for 3 h to obtain a Co-Zn heterojunction catalyst (ZnO-Co3O4).

[0089] Comparative Example 1

[0090] Following the preparation method of Example 1, 5 g of copper acetate was weighed and placed in an agate ball mill jar. The remaining steps were the same, and a CuO control sample (CuO) was prepared.

[0091] Comparative Example 2

[0092] Following the preparation method of Example 1, 5 g of cobalt acetate was weighed and placed in an agate ball mill jar. The remaining steps were the same, and a Co3O4 control sample (Co3O4) was prepared.

[0093] Comparative Example 3

[0094] Following the preparation method of Example 6, 2 g of cobalt acetate was weighed and placed in a stainless steel ball mill jar. The remaining steps were the same, and a Co3O4 control sample (Co3O4) was prepared.

[0095] Comparative Example 4

[0096] Following the preparation method of Example 6, 2 g of zinc acetate was weighed and placed in a stainless steel ball mill jar. The remaining steps were the same, and a ZnO control sample (ZnO) was prepared.

[0097] Structural testing

[0098] The transmission electron microscope (TEM) image of the Co-Cu heterojunction catalyst prepared in Example 1 is shown below. Figure 1 X-ray photoelectron spectroscopy (XPS) image is shown below. Figure 2The X-ray diffraction (XRD) patterns of the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown below. Figure 3 .from Figure 1 As can be seen, the two metal oxides form a highly uniformly dispersed composite phase structure with no obvious phase separation or metal agglomeration, and the active sites are fully exposed. Figure 2 and Figure 3 This indicates that the Co-Cu heterojunction catalyst is composed of Co3O4 and CuO, proving the successful synthesis of a pure-phase binary composite oxide.

[0099] The X-ray diffraction (XRD) patterns of the catalysts prepared in Example 6, Comparative Example 3, and Comparative Example 4 are shown below. Figure 4 .from Figure 4 It can be seen that the Co-Zn heterojunction catalyst prepared in Example 6 clearly shows the characteristic peaks of two substances, Co3O4 and ZnO, that is, the Co-Zn heterojunction catalyst is composed of Co3O4 and ZnO.

[0100] Performance testing

[0101] (Degradation effect of sulfamethoxazole)

[0102] Using sulfamethoxazole (SMX) as a model organic pollutant, the pollutant concentration in the simulated wastewater was 10 mg / L, the target wastewater volume for a single treatment was 250 mL, the catalyst dosage was 0.1 g / L, the persulfate concentration was 1.0 mM, and the reaction time was 30 min.

[0103] The degradation effect of the Co-Cu heterojunction catalyst (CuO-Co3O4) in Examples 1-5 on sulfamethoxazole activated by hydrogen persulfate was tested, and the results are as follows: Figure 5 As shown. From Figure 5 It can be seen that sulfamethoxazole can be degraded when the mass ratio of copper salt to cobalt salt is in the range of 3:2 to 50:1. Preferably, when the mass ratio of copper salt to cobalt salt is (4 to 20):1, the degradation rate of sulfamethoxazole can reach more than 90% in 30 minutes. More preferably, when the mass ratio of copper salt to cobalt salt is 4:1, the degradation effect is the best, and the degradation rate of sulfamethoxazole reaches 100% in about 25 minutes.

[0104] The effects of catalysts prepared in Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 1 + Comparative Example 2 (mass ratio 4:1) on the degradation of sulfamethoxazole in water by activated hydrogen persulfate were tested. The results are as follows: Figure 6 As shown. From Figure 6It can be seen that, under the same reaction conditions, the Co-Cu heterojunction catalyst synthesized in Example 1 has significantly better degradation efficiency and reaction rate for SMX than the single metal oxide catalyst. Moreover, the good performance of this catalyst is due to the formation of the heterojunction structure rather than simple physical mixing.

[0105] (Degradation effect of bisphenol A)

[0106] Bisphenol A was used as the model organic pollutant, with a pollutant concentration of 10 mg / L in the simulated wastewater. The target wastewater volume for a single treatment was 250 mL, the catalyst dosage was 0.1 g / L, the persulfate concentration was 1.0 mM, and the reaction time was 20 min.

[0107] The degradation performance of bisphenol A in water by the catalysts prepared in Example 6, Comparative Example 3, and Comparative Example 4 for activated hydrogen persulfate was tested. The experimental results are shown in [Figure Number]. Figure 7 Where C0 is the initial concentration of bisphenol A in water, and C is the concentration of bisphenol A in water after a certain degradation time. Figure 7 It can be seen that when the ZnO-Co3O4 addition amount is 0.1 g / L, the degradation rate of bisphenol A can reach 100% after 6 min of reaction. However, when the addition amount of ZnO and Co3O4 alone is 0.1 g / L, their degradation effect on bisphenol A is negligible. These results indicate that ZnO-Co3O4 has excellent catalytic performance as a persulfate and can be used for the effective removal of pollutants from water.

[0108] (Specific surface area test)

[0109] The nitrogen adsorption-desorption figures for the catalysts prepared in Example 1, Comparative Example 1, and Comparative Example 2 are shown in the attached figures. Figure 8 Aperture distribution is shown in Figure 9 While pure Co3O4 possesses the highest specific surface area and pore volume, it is predominantly composed of small mesopores. These tiny channels are prone to collapse and sintering during high-temperature calcination or reaction, leading to the burial of active sites and reducing the catalyst's cycle stability. In contrast, the pore size distribution of Co-Cu heterojunction catalysts shifts towards larger mesopores, forming a more stable pore structure. On one hand, the larger pore size reduces the mass transfer resistance between reactants and products, facilitating the diffusion and adsorption of pollutant molecules on the catalyst surface; on the other hand, the heterostructure inhibits grain aggregation and pore collapse, reducing cobalt ion dissolution and improving the catalyst's structural stability. Pure CuO, due to its extremely low pore volume and scarce pores, suffers from insufficient exposure of active sites and low mass transfer efficiency, exhibiting the worst catalytic performance. Therefore, Co-Cu heterojunction catalysts, through optimized pore structure, achieve a balance between specific surface area, mass transfer efficiency, and structural stability, providing crucial support for their superior catalytic performance.

[0110] (Continuous flow test)

[0111] The Co-Cu heterojunction catalyst prepared in Example 1 was used to activate the persulfate system for continuous degradation of sulfamethoxazole for 12 hours. The removal efficiency is shown in [Figure 1]. Figure 10 .from Figure 10 As can be seen, during the continuous 12-hour degradation process, the removal rate of sulfamethoxazole by Co-Cu heterojunction activated persulfate can reach 100%. The results indicate that the Co-Cu heterojunction catalyst has good stability.

[0112] It should be noted that although the technical solution of the present invention has been described with specific examples, those skilled in the art will understand that the present invention should not be limited thereto.

[0113] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or technical improvements to the embodiments in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for batch preparation of a cobalt-based heterojunction catalyst, characterized in that, Includes the following steps: The salts of metal M and cobalt salts were mechanically ball-milled to obtain a mixture; The mixture was calcined in air to obtain a MO-Co3O4 cobalt-based heterojunction catalyst. Wherein, M is one or both of Cu and Zn; The mass ratio of the salt of metal M to the cobalt salt is (1~50):

1.

2. The batch preparation method according to claim 1, characterized in that, The salt of metal M is an acetate of metal M; The cobalt salt is a cobalt acetate.

3. The batch preparation method according to claim 1 or 2, characterized in that, The ball-to-material ratio of the mechanical ball mill is (40~80):1; and / or, The conditions for the mechanical ball milling are: a ball milling speed of 100-600 rpm, a ball milling time of 1-10 hours, and a ball milling mode of forward rotation, reverse rotation, or alternating forward and reverse rotation.

4. The batch preparation method according to claim 3, characterized in that, The ball milling mode is to rotate forward for 30 minutes and then stop for 5-10 minutes, then rotate backward for 30 minutes and then stop for 5-10 minutes, repeating the cycle 1-10 times.

5. The batch preparation method according to any one of claims 1-4, characterized in that, The calcination temperature is 400-800℃, the heating rate is 1-5℃ / min, and the calcination time is 2-4 h.

6. A cobalt-based heterojunction catalyst, obtained by the batch preparation method according to any one of claims 1-5.

7. An application of a cobalt-based heterojunction catalyst obtained by the batch preparation method according to any one of claims 1-5 or the cobalt-based heterojunction catalyst according to claim 6 for water treatment, characterized in that, The cobalt-based heterojunction catalyst is used to decompose oxidants to generate reactive oxygen species to degrade pollutants in water.

8. The application according to claim 7, characterized in that, The active oxygen species are selected from one or more of sulfate radicals, hydroxyl radicals, singlet oxygen, and high-valence metal oxygen species.

9. The application according to claim 7 or 8, characterized in that, The oxidant is selected from one or more of ozone, hydrogen peroxide, and persulfate.

10. The application according to claim 9, characterized in that, The oxidant is persulfate, and the concentration of persulfate is 0.1~1.25 mM; and / or, The dosage of the cobalt-based heterojunction catalyst is 0.05~5.0 g / L.

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