Ozone oxidation catalysts, their preparation methods and applications

Abstract

This application relates to the field of catalyst technology, and more particularly to an ozone oxidation catalyst, its preparation method, and its application. The preparation method of the ozone oxidation catalyst of this application includes: providing a porous adsorption substrate; preparing a mixed solution containing an active metal salt and a complexing agent; wherein the active metal salt includes one or more of cobalt salt, iron salt, nickel salt, manganese salt, and copper salt; placing the porous adsorption substrate in the mixed solution and carrying out a hydrothermal reaction under pH 5-6 conditions; and then calcining the porous adsorption substrate after the hydrothermal reaction to obtain the ozone oxidation catalyst. The ozone oxidation catalyst prepared in this application has the characteristics of stable structure of the active metal component on the surface of the porous adsorption substrate, low metal ion dissolution, and good cycle performance. When used in wastewater treatment, it can improve the utilization rate of ozone, thereby achieving efficient removal of COD from wastewater under low-cost conditions.

Description

Technical Field

[0001] This application belongs to the field of catalyst technology, and in particular relates to an ozone oxidation catalyst, its preparation method and application. Background Technology

[0002] Industrial wastewater discharges are large in volume and complex in composition. Improper treatment can easily cause serious pollution to the local aquatic environment. Chemical Oxygen Demand (COD), as one of the important indicators of industrial wastewater, has attracted widespread attention regarding its corresponding treatment technologies. Currently, COD treatment technologies for industrial wastewater mainly include adsorption, chemical coagulation, membrane separation, biological methods, and advanced oxidation technologies.

[0003] Adsorption methods primarily utilize porous materials with large specific surface areas as adsorbents to adsorb pollutants in water, thereby purifying wastewater. However, these adsorbents have poor selectivity, and their adsorption efficiency decreases when the wastewater composition is complex. Furthermore, the adsorbents are difficult to recover and reuse. Chemical coagulation involves adding flocculants to wastewater, utilizing the flocculants' adsorption bridging, double-layer compression, and entrapment effects to remove pollutants. This method requires large quantities of flocculants, is costly, and improper treatment of the generated chemical sludge can easily cause secondary pollution. Membrane separation uses specially structured membranes to selectively allow certain components in wastewater to permeate, thereby reducing COD. This method has high investment and operating costs, a short membrane lifespan, and requires regular cleaning, making it difficult to apply industrially. Additionally, biological methods have relatively poor treatment efficiency and long treatment cycles, also hindering industrial application. Therefore, it is difficult to achieve good COD removal efficiency while ensuring economic viability when using these methods to treat industrial wastewater.

[0004] Advanced oxidation technologies primarily utilize the generation of highly oxidizing hydroxyl radicals under specific conditions to oxidize and degrade organic pollutants in water. Ozone oxidation, as a type of advanced oxidation technology, is characterized by its rapid reaction rate and low secondary pollution, making it suitable for treating recalcitrant wastewater. However, ozone is prone to ineffective decomposition in water, resulting in low utilization. Therefore, to improve ozone utilization, porous supports with large specific surface areas are needed to load active metal components for catalysis. Ozone oxidation catalysts are generally obtained by impregnating a porous support such as diatomaceous earth with an active metal component solution for ion exchange, followed by calcination. The resulting ozone oxidation catalyst has an unstable surface structure, and the active metal components on the porous support are easily dissolved. Therefore, it not only easily causes secondary pollution but also reduces its sustained catalytic capacity. Summary of the Invention

[0005] The purpose of this application is to provide an ozone oxidation catalyst, its preparation method, and its application, aiming to solve the problem of how to improve the surface stability of the ozone oxidation catalyst to enhance the catalytic effect.

[0006] To achieve the above-mentioned objectives, the technical solution adopted in this application is as follows:

[0007] In a first aspect, this application provides a method for preparing an ozone oxidation catalyst, comprising:

[0008] Provide porous adsorption substrates;

[0009] Prepare a mixed solution containing an active metal salt and a complexing agent; wherein the active metal salt includes one or more of cobalt salt, iron salt, nickel salt, manganese salt and copper salt;

[0010] The porous adsorption substrate is placed in a mixed solution and subjected to a hydrothermal reaction at a pH of 5–6. The porous adsorption substrate after the hydrothermal reaction is then calcined to obtain an ozone oxidation catalyst.

[0011] In one embodiment, the active metal salt includes cobalt salt and iron salt.

[0012] In one embodiment, at least one of the following conditions is met:

[0013] The molar ratio of cobalt in cobalt salts to iron in iron salts is 1:(1~3);

[0014] The weight ratio of the porous active substrate to the molar amount of iron in the iron salt is 10 g: (0.01~0.1) mol;

[0015] The cobalt salt is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride;

[0016] The iron salt is selected from at least one of ferric sulfate, ferric nitrate and ferric chloride.

[0017] In one embodiment, the hydrothermal reaction conditions include a temperature of 280–320°C and a time of 4–8 hours.

[0018] In one embodiment, the calcination conditions include a temperature of 420–480°C and a time of 4–8 hours.

[0019] In one embodiment, the porous adsorption substrate is selected from acid-modified porous adsorption substrates. The preparation steps of the acid-modified porous adsorption substrate include: placing the initial porous active substrate in a 0.8-1.2 mol / L dilute sulfuric acid solution and stirring for 5-7 hours, then filtering and washing to neutralize.

[0020] In one embodiment, at least one of the following conditions is met:

[0021] The porous adsorption substrate is selected from one or more of diatomaceous earth, activated alumina, activated carbon, and hydrotalcite-like materials;

[0022] The complexing agent is selected from one or more of citric acid, malic acid, lactic acid, and ethylenediaminetetraacetic acid.

[0023] Secondly, this application provides an ozone oxidation catalyst, which is prepared by the preparation method described above.

[0024] Thirdly, this application provides an application of the above-mentioned ozone oxidation catalyst in the ozone treatment of industrial wastewater.

[0025] In one embodiment, the weight ratio of the ozone oxidation catalyst to the volume of the industrial wastewater is (5-15) g: 1 L.

[0026] The ozone oxidation catalyst preparation method provided in the first aspect of this application involves placing a porous adsorption substrate in a mixed solution containing an active metal salt and a complexing agent, and subjecting it to a hydrothermal reaction under specific pH conditions, followed by calcination to obtain the ozone oxidation catalyst. During this preparation process, the active metal component can undergo hydrothermal synthesis to form a stable spinel structure in situ on the surface of the porous adsorption substrate under the complexing effect of the complexing agent. Subsequent calcination further enhances the stability of the structure. This not only increases the ozone catalytic active sites on the surface of the porous adsorption substrate but also reduces the dissolution of metal ions, lowering secondary pollution. More importantly, the structural stability of the porous adsorption substrate surface ensures that the prepared ozone oxidation catalyst retains excellent catalytic performance even after multiple cycles. Therefore, the ozone oxidation catalyst obtained by the preparation method of this application features a stable structure of the active metal component on the porous adsorption substrate surface, low metal ion dissolution, and good cycle performance. When used in wastewater treatment, it can improve ozone utilization, thereby achieving efficient COD removal from wastewater under low-cost conditions.

[0027] The ozone oxidation catalyst provided in the second aspect of this application is prepared by the ozone oxidation catalyst preparation method unique to this application. Based on the characteristics of the preparation process of hydrothermal synthesis combined with calcination, the ozone oxidation catalyst of this application has the characteristics of stable structure of active metal components on porous adsorption substrate surface, low metal ion dissolution, and good cycle performance. Therefore, such an ozone oxidation catalyst can improve the utilization rate of ozone and achieve efficient removal of COD from wastewater at low cost.

[0028] The ozone oxidation catalyst provided in the third aspect of this application is used in the ozone treatment of industrial wastewater. Based on the characteristics of the ozone oxidation catalyst of this application—stable structure of the active metal component on the porous adsorption substrate, low metal ion dissolution, and good cycle performance—this ozone oxidation catalyst is applied to ozone treatment of wastewater. Through the porous adsorption substrate, most pollutants are adsorbed onto the substrate surface, catalyzing ozone to generate hydroxyl radicals for rapid decomposition and oxidation of pollutants. The synergistic effect of the porous adsorption substrate and the stable surface structure of the active metal component enhances the catalytic effect of ozone, improving ozone utilization. Therefore, it has excellent application prospects in ozone treatment of industrial wastewater. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the preparation method of the ozone oxidation catalyst provided in the embodiments of this application;

[0031] Figure 2 This is the XRD pattern of the ozone oxidation catalyst provided in the embodiments of this application. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects 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.

[0033] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0034] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items.

[0035] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0036] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0037] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, any scaling up or down of the content of the relevant components according to the embodiments of this application is within the scope disclosed in the embodiments of this application. Specifically, the mass described in the embodiments of this application can be a mass unit known in the chemical industry, such as μg, mg, g, or kg.

[0038] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0039] The first aspect of this application provides a method for preparing an ozone oxidation catalyst, such as... Figure 1 As shown, the preparation method includes the following steps:

[0040] S01: Provides a porous adsorption substrate;

[0041] S02: Prepare a mixed solution containing an active metal salt and a complexing agent; wherein the active metal salt includes one or more of cobalt salt, iron salt, nickel salt, manganese salt and copper salt;

[0042] S03: The porous adsorption substrate is placed in a mixed solution and subjected to a hydrothermal reaction at a pH of 5-6. The porous adsorption substrate after the hydrothermal reaction is then calcined to obtain an ozone oxidation catalyst.

[0043] Ozone, as a strong oxidant, has a redox potential of 2.07V. The mechanism of ozone oxidation of organic pollutants in wastewater mainly involves two aspects: (a) the direct action of ozone; and (b) the indirect action following the decomposition of ozone to generate hydroxyl radicals (·OH). The former reaction is slow, while the latter produces ·OH with a redox potential of 2.8V, resulting in faster oxidation efficiency. Furthermore, the active sites on heterogeneous catalysts can promote the decomposition of ozone to generate ·OH, enhancing the efficiency of catalytic ozonation. The mechanism of ozone decomposition to generate ·OH is as follows:

[0044] (

[0045]

[0046]

[0047]

[0048] (5) HO3·→·OH+O2

[0049] As can be seen from the above reaction formula, every three molecules of ozone can generate two molecules of ·OH, which in turn oxidizes the organic matter in the wastewater, thereby reducing the COD content of the wastewater.

[0050] This application provides a method for preparing a heterogeneous ozone oxidation catalyst to improve ozone utilization and enhance the catalytic ozone oxidation effect of the catalyst. In this method, a porous adsorption substrate is placed in a mixed solution containing an active metal salt and a complexing agent and subjected to a hydrothermal reaction under specific pH conditions, followed by calcination to obtain the ozone oxidation catalyst. During this preparation process, the active metal component can form a stable spinel structure in situ on the surface of the porous adsorption substrate through hydrothermal synthesis under the complexing effect of the complexing agent. Subsequent calcination further strengthens the structural stability. This not only increases the ozone catalytic active sites on the surface of the porous adsorption substrate but also reduces the dissolution of metal ions, lowering secondary pollution. More importantly, the structural stability of the porous adsorption substrate surface ensures that the prepared ozone oxidation catalyst retains excellent catalytic performance even after multiple cycles. Therefore, the ozone oxidation catalyst obtained by the method of this application has the characteristics of stable active metal component structure on the porous adsorption substrate surface, low metal ion dissolution, and good cycle performance. When used in wastewater treatment, it can improve ozone utilization, thereby achieving efficient COD removal from wastewater under low-cost conditions.

[0051] In step S01, the porous adsorption substrate provided can be an acid-modified porous adsorption substrate.

[0052] The porous adsorption substrate used is a porous matrix material capable of supporting active metal components. The high adsorption capacity of the porous adsorption substrate and the catalytic activity of the supported active metal components synergistically enhance ozone removal of pollutants, thereby improving COD removal efficiency. Furthermore, acid treatment of the porous adsorption substrate reduces surface impurity content, increases the specific surface area and pore volume, thus providing a better carrier effect and allowing for effective hydrothermal reactions with the active metal components under the action of a complexing agent.

[0053] In one embodiment, the porous adsorption substrate may be selected from one or more of diatomaceous earth, activated alumina, activated carbon and hydrotalcite, with diatomaceous earth being preferred. The porous nature of diatomaceous earth has a large specific surface area, which is beneficial to the dispersion of active sites and provides more active sites.

[0054] In one embodiment, the acid-modified porous adsorbent substrate is prepared by acid treatment of an initial porous active substrate. The specific steps include: placing the initial porous active substrate in a 0.8–1.2 mol / L dilute sulfuric acid solution and stirring for 5–7 hours, then filtering and washing until the solution is neutral. Under these conditions, the acid treatment is more effective. In a specific embodiment, the acid treatment step includes: preparing a 0.8–1.2 mol / L dilute sulfuric acid solution, then adding a certain amount of the initial porous active substrate and stirring at room temperature (25–27°C) and 300–500 rpm for 5–7 hours; filtering and washing the porous active substrate until the washing solution is neutral; and drying to obtain the acid-modified porous active substrate.

[0055] Step S02 is the preparation step of a mixed solution containing an active metal salt and a complexing agent.

[0056] The active metal salt in the mixed solution includes one or more of cobalt, iron, nickel, manganese, and copper salts; specifically, it can be a soluble sulfate, nitrate, or chloride salt corresponding to each active metal. For example, the cobalt salt can be at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride; the iron salt can be at least one of ferric sulfate, ferric nitrate, and ferric chloride; the nickel salt can be at least one of nickel sulfate, nickel nitrate, and nickel chloride; the manganese salt can be at least one of manganese sulfate, manganese nitrate, and manganese chloride; and the copper salt can be at least one of copper sulfate, copper nitrate, and copper chloride. The complexing agent in the mixed solution is selected from one or more of citric acid, malic acid, lactic acid, and ethylenediaminetetraacetic acid, which have a good complexing effect on active metal ions. The specific preparation steps of the mixed solution include: adding the complexing agent and the required active metal salt to water and stirring to obtain the mixed solution.

[0057] In one embodiment, the active metal salt may include at least two of cobalt, iron, nickel, manganese, and copper salts. Further, the active metal salt includes cobalt and iron salts. Cobalt and iron exhibit better catalytic activity, and these two metal ions, through the action of a complexing agent, form spinel-structured cobalt ferrite in situ on the surface of the porous active substrate. This structurally stable ozone oxidation catalyst thus exhibits excellent cyclic catalytic performance.

[0058] Furthermore, the molar ratio of cobalt in the cobalt salt to iron in the iron salt is 1:(1-3). Under this ratio, the two metal ions grow in situ on the surface of the porous active substrate and have a better catalytic effect. More preferably, the molar ratio of cobalt in the cobalt salt to iron in the iron salt is 1:2.

[0059] Furthermore, the weight ratio of the porous active substrate to the molar amount of iron in the iron salt is 10 g: (0.05~0.15) mol. The synergistic effect of the porous adsorption substrate and the loaded active metal component is better at this ratio. Furthermore, the weight ratio of the porous active substrate to the molar amount of cobalt in the cobalt salt and the molar amount of iron in the iron salt is 10 g: 0.05 mol: 0.1 mol.

[0060] Step S03 is the hydrothermal reaction and calcination process.

[0061] The hydrothermal reaction is carried out at a pH of 5–6. Under these conditions, the material will not degrade, and a stable spinel structure can be synthesized in situ on the surface of the porous adsorption substrate. Specifically, the acid-modified porous adsorption substrate is placed in a mixed solution and stirred to form a suspension. Then, ammonia water (such as an ammonia solution with a mass dispersion of 26–30%) is added to adjust the pH to 5–6.

[0062] In one embodiment, the hydrothermal reaction conditions include: a temperature of 280–320°C, such as 280°C, 290°C, 300°C, 310°C, etc.; and a time of 4–8 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc. These conditions can significantly improve the efficiency of the hydrothermal reaction. After the hydrothermal reaction is complete, the mixture is filtered and the filter residue is washed until the washing liquid is neutral. The washed material is then transferred to a muffle furnace for calcination.

[0063] In one embodiment, the calcination conditions include: a temperature of 420–480°C, such as 420°C, 430°C, 450°C, 460°C, etc.; and a time of 4–8 hours, such as 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, etc. These conditions can significantly improve calcination efficiency. After calcination, further grinding yields a powdered porous adsorbent substrate loaded with active metal (stable spinel structure), which is the ozone oxidation catalyst.

[0064] The second aspect of this application provides an ozone oxidation catalyst, which is prepared by the preparation method described above in the embodiments of this application.

[0065] The ozone oxidation catalyst preparation method unique to this application has the characteristics of hydrothermal synthesis combined with calcination. Therefore, such an ozone oxidation catalyst has the characteristics of stable structure of active metal components on porous adsorption substrate surface, low metal ion dissolution, and good cycle performance. Thus, the ozone oxidation catalyst of this application can improve the utilization rate of ozone and achieve efficient removal of COD from wastewater at low cost.

[0066] The third aspect of this application provides an application, namely, the application of the ozone oxidation catalyst prepared by the above preparation method in ozone treatment of industrial wastewater.

[0067] The ozone oxidation catalyst based on the embodiments of this application has the characteristics of stable structure of active metal components on porous adsorption substrate, low metal ion dissolution, and good cycle performance. Therefore, when this ozone oxidation catalyst is applied to ozone treatment of wastewater, most pollutants are adsorbed onto the surface of the porous adsorption substrate, and ozone is catalyzed to generate hydroxyl radicals to rapidly decompose and oxidize pollutants. The synergistic effect of the porous adsorption substrate and the active metal components with stable surface structure enhances the catalytic effect of ozone and improves the utilization rate of ozone, thus showing good application prospects in ozone treatment of industrial wastewater.

[0068] In one embodiment, the weight ratio of the ozone oxidation catalyst to the volume of industrial wastewater is (5-15) g: 1 L. For example, 5 g, 8 g, 10 g, 12 g, or 15 g of the ozone oxidation catalyst of this application can be used in 1 L of industrial wastewater. Because the embodiments of this application utilize a porous adsorption substrate with a large specific surface area to support the active metal component, and a structurally stable ozone oxidation catalyst is prepared through hot water synthesis, the utilization rate of ozone can be improved. Therefore, the low-dosage ozone oxidation catalyst has a good catalytic effect, and efficient removal of COD from wastewater can be achieved under low-cost conditions.

[0069] Specifically, the COD removal efficiency of the ozone oxidation catalyst was verified under the conditions of room temperature and ozone flux of 9 mg / min. Compared with the adsorption efficiency of a single porous adsorption substrate, ozone catalysis alone, adsorption of a porous adsorption substrate plus ozone catalysis, and ozone catalysis by cobalt ferrite, the ozone oxidation catalyst prepared in this application has a significant improvement. Moreover, the catalyst still has a high COD removal efficiency after 6 cycles, thus exhibiting good cycle performance.

[0070] The following description is based on specific embodiments.

[0071] Example 1

[0072] An ozone oxidation catalyst, prepared by the following steps:

[0073] (1) Prepare 250 mL of 1 mol / L dilute sulfuric acid solution, add 10 g of diatomaceous earth and stir for 6 h at room temperature and 400 rpm. Filter and wash the diatomaceous earth material until the washing solution is neutral. After drying, obtain acid-modified diatomaceous earth material.

[0074] (2) Add 9.6g citric acid, 14.05g CoSO4·7H2O, and 20g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified diatomaceous earth prepared in step (1) to form a suspension. Use 28% ammonia water to control the pH of the suspension to 5. Stir at room temperature for 3h and then transfer to a reaction vessel. Perform hydrothermal reaction at 300℃ for 6h. Filter the mixture after hydrothermal reaction and wash the filter residue until the washing liquid is neutral. Transfer the washed material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the diatomaceous earth material loaded with cobalt and iron, which is the ozone oxidation catalyst. Its crystal structure X-ray diffraction (XRD) is as follows: Figure 2 As shown in the figure, the characteristic diffraction peaks of diatomaceous earth amorphous opal and cobalt ferrite with spinel structure are included, indicating that the prepared ozone oxidation catalyst has a stable spinel structure generated in situ.

[0075] Catalytic applications of ozone oxidation catalysts:

[0076] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (industrial wastewater parameters are shown in Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration stops, filter (this completes one cycle; if you want to test it again, repeat the same steps with the used ozone oxidation catalyst). Analyze the filtrate. The COD in the filtrate decreased to 185.2mg / L, and the COD removal rate was 85%. Repeat the test multiple times.

[0077] Table 1 Water quality indicators of industrial wastewater

[0078] Samples to be processed COD (mg / L) Oil (mg / L) pH Ammonium sulfate condensate 1236.8 18 7.76

[0079] Example 2

[0080] An ozone oxidation catalyst, prepared by the following steps:

[0081] (1) Prepare acid-modified diatomaceous earth material, the same as in Example 1.

[0082] (2) Add 9.6g citric acid, 14.05g CoSO4·7H2O and 30g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified diatomite prepared in step (1) to form a suspension. Use 28% ammonia water to control the pH of the suspension to 5. Stir at room temperature for 3h and then transfer to a reaction vessel. Perform hydrothermal reaction at 300℃ for 6h. Filter the mixture after hydrothermal reaction and wash the filter residue until the washing liquid is neutral. Transfer the washed material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the diatomite material loaded with cobalt iron, which is the ozone oxidation catalyst.

[0083] Catalytic applications of ozone oxidation catalysts:

[0084] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (see Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration, filter the solution. Analyze the filtrate. The COD in the filtrate decreased to 292.3mg / L, and the COD removal rate was 76.4%. Repeat the test multiple times.

[0085] Example 3

[0086] An ozone oxidation catalyst, prepared by the following steps:

[0087] (1) Prepare acid-modified diatomaceous earth material, the same as in Example 1.

[0088] (2) Add 9.6g citric acid, 14.05g CoSO4·7H2O and 10g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified diatomite prepared in step (1) to form a suspension. Use 28% ammonia water to control the pH of the suspension to 5. Stir at room temperature for 3h and then transfer to a reaction vessel. Perform hydrothermal reaction at 300℃ for 6h. Filter the mixture after hydrothermal reaction and wash the filter residue until the washing liquid is neutral. Transfer the washed material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the diatomite material loaded with cobalt iron, which is the ozone oxidation catalyst.

[0089] Catalytic applications of ozone oxidation catalysts:

[0090] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (see Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration, filter the solution. Analyze the filtrate. The COD in the filtrate decreased to 346.1mg / L, and the COD removal rate was 72%. Repeat the test multiple times.

[0091] Example 4

[0092] An ozone oxidation catalyst, prepared by the following steps:

[0093] (1) Prepare 250 mL of 1 mol / L dilute sulfuric acid solution, add 10 g of activated alumina and stir for 6 h at room temperature and 400 rpm. Filter and wash until the washing solution is neutral, and dry to obtain acid-modified activated alumina.

[0094] (2) Add 9.6g citric acid, 14.05g CoSO4·7H2O and 20g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified active alumina prepared in step (1) to form a suspension. Use 28% ammonia water to control the pH of the suspension to 5. Stir at room temperature for 3h and then transfer to a reaction vessel. Perform hydrothermal reaction at 300℃ for 6h. Filter the mixed solution after hydrothermal reaction and wash the filter residue until the washing liquid is neutral. Transfer the washed material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the cobalt-iron-loaded active alumina material, which is the ozone oxidation catalyst.

[0095] Catalytic applications of ozone oxidation catalysts:

[0096] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (see Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration, filter the solution. Analyze the filtrate. The COD in the filtrate decreased to 465.9mg / L, and the COD removal rate was 62.3%. Repeat the test multiple times.

[0097] Example 5

[0098] An ozone oxidation catalyst, prepared by the following steps:

[0099] (1) Prepare acid-modified diatomaceous earth material, the same as in Example 1.

[0100] (2) Add 9.6g citric acid, 12.48g CuSO4·5H2O and 20g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified diatomite prepared in step (1) to form a suspension. Use 28% ammonia water to control the pH of the suspension to 5. Stir at room temperature for 3h and then transfer to a reaction vessel. Perform hydrothermal reaction at 300℃ for 6h. Filter the mixture after hydrothermal reaction and wash the filter residue until the washing liquid is neutral. Transfer the washed material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the copper and iron loaded diatomite material, which is the ozone oxidation catalyst.

[0101] Catalytic applications of ozone oxidation catalysts:

[0102] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (see Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration, filter the solution. Analyze the filtrate. The COD in the filtrate decreased to 592.3mg / L, and the COD removal rate was 52.1%. Repeat the test multiple times.

[0103] Comparative Example 1

[0104] The preparation steps of using acid-modified diatomaceous earth material as an ozone oxidation catalyst are as follows: 250 mL of 1 mol / L dilute sulfuric acid solution is prepared, 10 g of diatomaceous earth is added and stirred at room temperature and 400 rpm for 6 h, the diatomaceous earth material is filtered and washed until the washing solution is neutral, and then dried to obtain acid-modified diatomaceous earth material.

[0105] Take 5g of the acid-modified diatomaceous earth material obtained in the above steps into a 1L beaker, add 500mL of prepared industrial wastewater (see Table 1), and stir continuously at 400rpm for 3h. After stirring is stopped, filter. Take the filtrate for analysis. The COD in the filtrate decreased to 871.3mg / L, and the COD removal rate was 29.5%. Repeat the test multiple times.

[0106] Comparative Example 2

[0107] Acid-modified diatomaceous earth was used as an ozone oxidation catalyst, and the preparation steps were the same as those in Comparative Example 1.

[0108] 5g of acid-modified diatomaceous earth material was placed in a 1L volume air flotation column, and 500mL of prepared industrial wastewater (see Table 1) was added. Ozone was introduced from the bottom of the air flotation column using an ozone generator at a flux of 9mg / min for 3 hours. After aeration was stopped, the column was filtered. The filtrate was analyzed, and the COD in the filtrate was reduced to 800.9mg / L, with a COD removal rate of 35.2%. The test was repeated multiple times.

[0109] Comparative Example 3

[0110] The preparation steps of using cobalt ferrite as an ozone oxidation catalyst are as follows: 14.05g CoSO4·7H2O and 20g Fe2(SO4)3 were added to 500mL of deionized water and stirred to form a mixed solution. The pH of the solution was adjusted to 5 using 28% ammonia water. The mixed solution was filtered and the material was washed until the washing liquid was neutral. The washed material was transferred to a muffle furnace and calcined at 450℃ for 6h. After grinding, cobalt ferrite was obtained.

[0111] 5g of cobalt ferrite material was placed in a 1L volume air flotation column, and 500mL of prepared industrial wastewater was added (see Table 1). Ozone was introduced from the bottom of the air flotation column using an ozone generator at a flux of 9mg / min for 3 hours. After aeration, the solution was filtered. The filtrate was analyzed, and the COD in the filtrate was reduced to 647.3mg / L, with a COD removal rate of 47.7%. The test was repeated multiple times.

[0112] Comparative Example 4

[0113] An ozone oxidation catalyst, prepared by the following steps:

[0114] (1) Prepare acid-modified diatomaceous earth material, the same as in Example 1.

[0115] (2) Add 14.05g CoSO4·7H2O and 20g Fe2(SO4)3 to 500mL of deionized water and stir to form a mixed solution. Add the acid-modified diatomite prepared in step (1) and impregnate for 6h. Filter the impregnated mixture and dry it at 80℃ for 8h. Transfer the dried material to a muffle furnace and calcine at 450℃ for 6h. After grinding, obtain the diatomite material loaded with cobalt and iron, which is the ozone oxidation catalyst.

[0116] Catalytic applications of ozone oxidation catalysts:

[0117] Take 5g of the ozone oxidation catalyst material obtained in the above steps and place it in a 1L volume air flotation column. Add 500mL of prepared industrial wastewater (see Table 1). Use an ozone generator to introduce ozone from the bottom of the air flotation column at a flux of 9mg / min for 3 hours. After aeration, filter the solution. Analyze the filtrate. The COD in the filtrate decreased to 280.7mg / L, and the COD removal rate was 77.3%. Repeat the test multiple times.

[0118] Performance testing

[0119] The application effect data of the ozone oxidation catalysts prepared in Examples 1-5 and Comparative Examples 1-4 are shown in Table 2 below.

[0120] Table 2

[0121]

[0122]

[0123] As can be seen from the data in Table 2 above, during the preparation of the ozone oxidation catalyst based on the embodiments of this application, the active metal component can form a stable spinel structure in situ on the surface of the porous adsorption substrate through hydrothermal synthesis under the complexation effect of the complexing agent. Therefore, the metal ion dissolution is small, and the ozone oxidation catalyst has good cycle performance, which can better remove COD from the wastewater. The ozone oxidation catalyst prepared in Example 1 has the best catalytic effect.

[0124] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. Use of an ozone oxidation catalyst in the treatment of industrial wastewater with ozone, characterized in that, The method for preparing the ozone oxidation catalyst includes: A porous adsorption substrate is provided, wherein the porous adsorption substrate includes diatomaceous earth; Prepare a mixed solution containing an active metal salt and a complexing agent; wherein the active metal salt includes cobalt salt and iron salt; The porous adsorption substrate is placed in the mixed solution and subjected to a hydrothermal reaction at a pH of 5-6. Under the action of the complexing agent, the active metal component in the active metal salt forms a spinel structure in situ on the surface of the porous adsorption substrate. Then, the porous adsorption substrate after the hydrothermal reaction is calcined to obtain the ozone oxidation catalyst.

2. The application as described in claim 1, characterized in that, At least one of the following conditions must be met: The molar ratio of cobalt in the cobalt salt to iron in the iron salt is 1:(1~3). The weight ratio of the porous active substrate to the molar amount of iron in the iron salt is 10 g : (0.05~0.15) mol; The cobalt salt is selected from at least one of cobalt sulfate, cobalt nitrate, and cobalt chloride; The iron salt is selected from at least one of ferric sulfate, ferric nitrate, and ferric chloride.

3. The application as described in claim 1, characterized in that, The conditions for the hydrothermal reaction include: a temperature of 280~320℃ and a time of 4~8h.

4. The application as described in claim 1, characterized in that, The calcination conditions include a temperature of 420~480℃ and a time of 4~8h.

5. The application as described in any one of claims 1-4, characterized in that, The porous adsorption substrate is selected from acid-modified porous adsorption substrates. The preparation steps of the acid-modified porous adsorption substrate include: placing the initial porous active substrate in a 0.8~1.2mol / L dilute sulfuric acid solution and stirring for 5~7h, then filtering and washing to neutralize it.

6. The application as described in any one of claims 1-4, characterized in that, The complexing agent is selected from one or more of citric acid, malic acid, lactic acid, and ethylenediaminetetraacetic acid.

7. The application as described in any one of claims 1-4, characterized in that, The weight ratio of the ozone oxidation catalyst to the volume of the industrial wastewater is (5~15) g: 1 L.

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