Cobalt hydroxide microsphere / metal organic framework composite catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of water treatment, and particularly discloses a cobalt hydroxide microsphere / metal organic framework composite catalyst as well as a preparation method and application thereof. The cobalt hydroxide microsphere / metal organic framework composite catalyst is prepared from the following raw materials: alkyl cobalt microspheres and metal organic framework nanoparticles; the weight ratio of the alkyl cobalt microspheres to the metal organic framework nanoparticles is 1: (0.1-5.0). The composite catalyst prepared by the invention has the characteristics of rapidly and efficiently exciting PMS in a water body to generate active free radicals to degrade emerging organic pollutants, is not easy to migrate and convert in a water environment, and has extremely low dissolution rate of main active substances and small harm to the environment.

Description

Technical Field

[0001] The present application belongs to the field of water treatment technology, and specifically relates to the field of stimulating monopersulfate to degrade emerging organic pollutants in water. More specifically, it relates to a cobalt hydroxide microsphere / metal organic framework composite catalyst and its preparation method and application. Background Art

[0002] Water is an essential element for human survival. However, about 97.5% of the water on the earth is distributed in the ocean and cannot be effectively used. Only about 1% of the water source is available for human use. Therefore, the problem of varying degrees of damage to the water environment caused by human activities cannot be ignored. In recent years, with the increasing production and application of new substances in the agricultural and industrial sectors, human activities have created huge material wealth, but this has also led to an increasing variety of pollutants in sewage and wastewater discharge. Water pollution has increasingly become a major challenge to human survival. The composition of pollutants in the water environment is complex. With the development of analytical chemistry technology, more and more pollutants have been detected in the water environment. What is worrying is emerging organic contaminants (EOCs). This term includes not only known types of pollutants, but also newly developed compounds that have negative effects on the environment and human health.

[0003] EOCs originate from hundreds of pollution sources and are a large and diverse class of organic compounds, including but not limited to pharmaceuticals and personal care products (PPCPs), pesticides, veterinary drugs, industrially prepared compounds and their by-products, and food additives. These pollutants are highly toxic and have a short half-life. Coupled with continuous human use, even trace levels of pollutants may cause huge environmental risks. Since the 1970s, developed countries have built a large number of public sewage treatment plants and have made certain achievements in point source treatment. The water quality of human discharge has been improved to a certain extent. However, since emerging organic pollutants are difficult to be naturally purified by the environment, the concentration of pollutants in water bodies continues to rise, and the water pollution problem has become more serious.

[0004] Many EOCs are difficult to remove by traditional drinking water and wastewater treatment technologies. In order to remove EOCs from contaminated water, people have developed a variety of technologies, including adsorption and advanced oxidation processes (AOPs). Among the adsorption technologies, the use of activated carbon, carbon nanotubes, carbon fibers, metal organic frameworks and ion exchange resins can adsorb EOCs to a certain extent. However, these adsorption methods have serious disadvantages, including: 1) the technology cannot degrade EOCs and achieve detoxification; 2) the regeneration cost of the adsorbent is high, and expensive and toxic organic solvents are usually required, resulting in a large amount of regeneration waste residues, which requires additional expensive treatment and disposal costs. Therefore, the development of new and efficient processes for treating EOCs has become a research hotspot.

[0005] Advanced oxidation technology is an oxidation technology developed in the 1980s. It is mainly used for the treatment of refractory organic pollutants. It has been a technology that has attracted much attention in wastewater treatment because of its high degradation efficiency and strong deep treatment capacity. The traditional concept of AOPs was proposed by Glaze et al. in 1987: an oxidation technology that uses the highly oxidizing hydroxyl radicals (·OH) generated in the reaction to oxidize and decompose or even mineralize organic pollutants. ·OH has a high standard redox potential (E0 = 1.8-2.7V) and can degrade most organic pollutants, converting them into low-toxic, easily biodegradable small molecules or even directly mineralizing them into inorganic substances.

[0006] With the continuous deepening of research, various types of derivative advanced oxidation technologies based on traditional theories have also emerged. Among them, the method based on sulfate free radicals is particularly favored by researchers due to its advantages such as fast degradation rate, good pH adaptability, and high degree of mineralization. The core of sulfate free radical advanced oxidation technology is the activation of persulfates (permonosulfate (PMS) and peroxydisulfate (PDS)). Among them, PMS is easier to activate and produce sulfate free radicals than PDS due to its highly asymmetric molecule. At present, studies have shown that transition metals can catalyze PMS to produce sulfate free radicals, but transition metals are usually used in large amounts when catalyzing PMS, and excessive transition metals are also a heavy metal pollutant while catalyzing PMS, which will cause secondary pollution to water bodies. Summary of the invention

[0007] In order to solve the above technical problems, the present application provides a cobalt hydroxide microsphere / metal organic framework composite catalyst and a preparation method thereof, and uses the same to efficiently excite PMS in water to generate active free radicals OH and / or SO4 -, · Use active free radicals with strong oxidizing properties to oxidatively decompose or even mineralize emerging organic pollutants. The emerging organic pollutants include but are not limited to pharmaceuticals and personal care products (PPCPs), antibiotics / resistance genes, perfluoroalkyl compounds (PFAS), etc.

[0008] In the first aspect, the present application provides a cobalt hydroxide microsphere / metal organic framework composite catalyst, which adopts the following technical solution: A cobalt hydroxide microsphere / metal organic framework composite catalyst, the raw materials used include alkyl cobalt microspheres and metal organic framework nanoparticles; the weight ratio of the alkyl cobalt microspheres to the metal organic framework nanoparticles is 1:(0.1-5.0).

[0009] More specifically, the alkyl cobalt microspheres are prepared by the following method: Cobalt nitrate hexahydrate, isopropanol and glycerol are mixed as raw materials, reacted at a temperature of 175-185° C. for 5.5-6.5 hours, and washed and precipitated after solid-liquid separation, dried and ground to obtain alkyl cobalt microspheres.

[0010] More specifically, the metal organic framework nanoparticles include one or more of MOF-74 nanoparticles, ZIF-8 nanoparticles, ZIF-67 nanoparticles, and MIL-88A nanoparticles.

[0011] More specifically, the metal elements doped in the metal organic framework nanoparticles include one or more of cobalt, iron, manganese and copper.

[0012] In the present application, the inventors describe cobalt-doped MOF-74 nanoparticles (Co-MOF-74-NP) as metal organic framework nanoparticles.

[0013] The Co-MOF-74-NP was prepared by the following method: Cobaltous(II) acetate tetrahydrate, methanol and 2,5-dihydroxyterephthalic acid were mixed and stirred at room temperature for 2-3 hours. After solid-liquid separation, the precipitate was washed, dried and ground to obtain Co-MOF-74-NP.

[0014] In the present application, the raw material mixing can be achieved by means of stirring and / or ultrasonic dispersion known to those skilled in the art.

[0015] The solid-liquid separation is achieved by centrifugation and / or suction filtration known to those skilled in the art. If suction filtration is used, a 0.22 μm organic filter membrane and / or a water membrane is used.

[0016] The washing is performed by washing 1-3 times with the solvent used in synthesizing the material, and then washing with ultrapure water until neutral.

[0017] The drying conditions are: drying at a temperature of 60-80° C. for 12 hours.

[0018] Through the above technical scheme, the present application uses alkyl cobalt microspheres (s-CoA) and metal organic framework nanoparticles (MOF-NP) as raw materials, and under certain temperature and time conditions, prepares a cobalt hydroxide microsphere / metal organic framework (CoMS / MOFs) composite catalyst with metal organic framework as carrier, and cobalt hydroxide microspheres are loaded on the metal organic framework carrier. Since the alkyl cobalt microspheres and metal organic framework nanoparticles can be firmly combined together during the hydrothermal reaction, the CoMS / MOFs composite catalyst prepared by the present application is not easy to migrate and transform in an aqueous environment, and the main active substance dissolution rate is extremely low, and the harm to the environment is relatively small. At the same time, the CoMS / MOFs composite catalyst also has good sedimentation performance, can be separated from the water body in a short time after use, and can realize the green pollution-free, low-energy-consumption rapid regeneration of the catalyst by simple filtration and washing, and the stability is relatively high, and the cycle of pollutant degradation-material regeneration can be carried out continuously for many times.

[0019] In addition, the CoMS / MOFs composite catalyst prepared in the present application can give full play to the synergistic effect of the two materials, CoMS and MOFs, and the internal pore structure is distributed in a large number of multi-levels, with a positively large specific surface area, a significant capillary effect, excellent ion exchange performance, diversified surface functional groups, and abundant active sites. Therefore, it has the effect of quickly and efficiently stimulating PMS to produce active free radicals to degrade new organic pollutants in water bodies.

[0020] Preferably, the weight ratio of the alkyl cobalt microspheres to the metal organic framework nanoparticles is 1:(0.5-1.0).

[0021] Alkyl cobalt microspheres and metal organic framework nanoparticles can be firmly combined in the hydrothermal reaction, and give full play to the synergy between the two materials, so that the prepared CoMS / MOFs composite catalyst can efficiently excite PMS to produce active free radicals. Since hydroxy cobalt is the main active substance in the whole catalyst, the above technical scheme is used to further optimize the ratio between alkyl cobalt microspheres and metal organic framework nanoparticles, so that the proportion of CoMS in the prepared composite catalyst is relatively high, and it can be more fully loaded on MOFs, further improving the excitation ability of CoMS / MOFs composite catalyst to PMS, thereby improving the degradation effect. It has been proved by experimental data that when the weight ratio of alkyl cobalt microspheres and metal organic framework nanoparticles is 1: 1, the prepared CoMS / MOFs composite catalyst has the strongest excitation ability to PMS and the best degradation effect on emerging organic pollutants in water bodies.

[0022] In the second aspect, the present application provides a method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst, which adopts the following technical scheme: A method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: mixing alkyl cobalt microspheres and metal organic framework nanoparticles as raw materials, subjecting them to hydrothermal reaction at a temperature of 135-165°C for 12 hours, washing and precipitating after solid-liquid separation, and drying to obtain the cobalt hydroxide microsphere / metal organic framework composite catalyst.

[0023] In a third aspect, the present application provides an application of a cobalt hydroxide microsphere / metal organic framework composite catalyst, using the following technical solution: An application of a cobalt hydroxide microsphere / metal organic framework composite catalyst, wherein the cobalt hydroxide microsphere / metal organic framework composite catalyst and PMS are added to an EOCs solution, wherein the temperature of the EOCs solution is not higher than 50°C and the pH value is greater than 3.

[0024] More specifically, the concentration of the EOCs solution is greater than 20 ng / L.

[0025] More specifically, 0.01-200 parts by weight of cobalt hydroxide microspheres / metal organic framework composite catalyst is added to each liter of the EOCs solution.

[0026] More specifically, the molar concentration of the PMS in the EOCs solution is 0.8-1.2 mmol / L.

[0027] Through the above technical solution, the present application adds a certain amount of CoMS / MOFs composite catalyst and PMS to a certain concentration of EOCs solution, which can stably and efficiently catalyze PMS to degrade EOCs in water and effectively remove EOCs pollutants in the solution. In the present application, the inventor takes the concentration of EOCs solution as 10 mg / L, the molar concentration of PMS in the EOCs solution as 0.1 mmol / L, and adds 0.1 g of CoMS / MOFs composite catalyst per liter of the EOCs solution as an example for illustration.

[0028] The application scenarios of this application include but are not limited to drinking water treatment, domestic sewage treatment, hospital sewage treatment, aquaculture sewage treatment, industrial wastewater treatment, landfill leachate treatment, groundwater remediation and emergency treatment of natural water pollution, etc. In different application scenarios, the cobalt hydroxide microspheres / metal organic framework composite catalyst has different contact forms with the water to be treated.

[0029] Specifically, in water treatment such as drinking water treatment, domestic sewage treatment, hospital sewage treatment, aquaculture sewage treatment, industrial wastewater treatment, and landfill leachate treatment, the steps are as follows: a. For some industrial wastewater and landfill leachate, it is necessary to preset sewage cooling pools and sewage pH adjustment pools to adjust and homogenize the sewage temperature and pH value so that the sewage temperature is no higher than 50°C and the pH value is greater than 3; b. Filling a reaction tower with the cobalt hydroxide microsphere / metal organic framework composite catalyst, using a water pump to continuously pump water and PMS solution into the reaction tower, and discharging the water after the pollutant reaction.

[0030] In water treatment such as groundwater remediation and emergency treatment of natural water pollution, the steps are as follows: a. The cobalt hydroxide microsphere / metal organic framework composite catalyst is loaded into a SMS non-woven fabric bag (SMS non-woven fabric is a composite non-woven fabric, which is a composite product of spunbond and meltblown, and has the characteristics of being non-toxic and tasteless, highly efficient in isolating bacteria, high strength, and good filtering performance), and is placed in the water body to be repaired or treated in an emergency through a well or other means; b. Add PMS to the water body to be repaired according to the concentration requirements for in-situ restoration; c. Check water quality regularly and add PMS to the water at any time.

[0031] In summary, this application has the following beneficial technical effects: 1. The CoMS / MOFs composite catalyst prepared in this application has the characteristics of rapidly and efficiently stimulating PMS in water to produce active free radicals to degrade emerging organic pollutants; 2. The CoMS / MOFs composite catalyst prepared in this application is not easy to migrate and transform in the water environment, and the dissolution rate of the main active substances is extremely low, which has little harm to the environment; 3. The CoMS / MOFs composite catalyst prepared in this application has good sedimentation performance and can be separated from the water body in a short time after use. Moreover, the green, pollution-free, low-consumption and rapid regeneration of the catalyst can be achieved through simple filtration and washing; 4. The CoMS / MOFs composite catalyst prepared in the present application has high stability and can perform the pollutant degradation-material regeneration cycle multiple times in succession. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a transmission electron microscope photograph of the CoMS / MOFs composite catalyst prepared in Examples 1-4 of the present application; Figure 2 It is a papaverine degradation effect diagram of Application Example 4 of the present application and Comparative Application Examples 3-4; Figure 3 This is a diagram showing the effect of repeatedly performing experiments to degrade papaverine in water using Application Example 4 as an example. DETAILED DESCRIPTION

[0033] The present application is further described in detail below in conjunction with the accompanying drawings, embodiments and application examples.

[0034] The EOCs solution of the present application includes but is not limited to drugs and personal care products (PPCPs), antibiotics / resistance genes, perfluoro / polyfluoroalkyl compounds (PFAS), etc. In the specific implementation of the present application, the PPCPs solution is used as an example for illustration. The PPCPs solution can be a solution containing various antibiotics, synthetic musks, analgesics, antihypertensive drugs, contraceptives, hypnotics, diet pills, hair sprays, hair dyes and bactericides. More specifically, the present application is described by taking an aqueous solution containing papaverine as an example, in which the concentration of papaverine in the solution is 10 mg / L and the pH value is neutral.

[0035] Unless otherwise specified, the raw materials used in this application are all commercially available products, wherein the alkyl cobalt microspheres and cobalt-doped metal organic framework nanoparticles are prepared by the following method: Preparation Example 1.1 The preparation method of alkyl cobalt microspheres comprises the following steps: 10 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was dispersed and dissolved in 60 mL of isopropanol, and then 16 mL of propylene glycol was added. After magnetic stirring for 30 minutes until it was completely dissolved, the mixed liquid was transferred to a flange-type high-pressure reactor with a polytetrafluoroethylene liner, and reacted at 175°C for 6.5 hours. After cooling to room temperature, the product was centrifuged and washed with ethanol for three times, and then dried at 60°C for 12 hours. After grinding, alkyl cobalt microspheres were obtained.

[0036] Preparation Example 1.2 The preparation method of alkyl cobalt microspheres comprises the following steps: 10 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was dispersed and dissolved in 60 mL of isopropanol, and then 16 mL of propylene glycol was added. After magnetic stirring for 30 minutes until it was completely dissolved, the mixed liquid was transferred to a flange-type high-pressure reactor with a polytetrafluoroethylene liner, and reacted at 185°C for 5.5 hours. After cooling to room temperature, the product was centrifuged and washed with ethanol for three times, and then dried at 80°C for 12 hours. After grinding, alkyl cobalt microspheres were obtained.

[0037] Preparation Example 2.1 The method for preparing cobalt-doped metal organic framework nanoparticles comprises the following steps: 2 mmol of cobalt(II) acetate tetrahydrate (C4H6CoO4·4(H2O)) was dispersed and dissolved in 50 mL of methanol. Under continuous stirring, 25 mL of a methanol solution containing 0.75 mmol of 2,5-dihydroxyterephthalic acid was added dropwise and mixed. Stirring was continued at room temperature for 2 hours. The obtained product was separated from the solid by a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol, then washed twice with ultrapure water, dried at 60°C for 12 hours, and ground to obtain Co-MOF-74-NP.

[0038] Preparation Example 2.2 The method for preparing cobalt-doped metal organic framework nanoparticles comprises the following steps: 2 mmol of cobalt(II) acetate tetrahydrate (C4H6CoO4·4(H2O)) was dispersed and dissolved in 50 mL of methanol. Under continuous stirring, 25 mL of a methanol solution containing 0.75 mmol of 2,5-dihydroxyterephthalic acid was added dropwise and mixed. Stirring was continued at room temperature for 3 hours. The obtained product was separated from the solid by a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol, then washed twice with ultrapure water, dried at 80°C for 12 hours, and ground to obtain Co-MOF-74-NP.

[0039] Example 1 A method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: 10 g of the alkyl cobalt microspheres prepared in Preparation Example 1.1 and 1 g of the metal organic framework nanoparticles prepared in Preparation Example 2.1 were stirred and mixed, and then subjected to hydrothermal reaction at 135°C for 12 hours. The obtained product was separated into solid and liquid using a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol and then washed twice with ultrapure water. The mixture was dried at 60°C for 12 hours to obtain a cobalt hydroxide microsphere / metal organic framework composite catalyst.

[0040] Example 2 A method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: 10 g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 50 g of the metal organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then subjected to hydrothermal reaction at 165°C for 12 hours. The obtained product was separated into solid and liquid using a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain a cobalt hydroxide microsphere / metal organic framework composite catalyst.

[0041] Example 3 A method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: 10 g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 5 g of the metal organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then subjected to hydrothermal reaction at 165°C for 12 hours. The obtained product was separated into solid and liquid using a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain a cobalt hydroxide microsphere / metal organic framework composite catalyst.

[0042] Example 4 A method for preparing a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: 10 g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 10 g of the metal organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then subjected to hydrothermal reaction at 165°C for 12 hours. The obtained product was separated into solid and liquid using a 0.22 μm organic filter membrane, and the precipitate was washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain a cobalt hydroxide microsphere / metal organic framework composite catalyst.

[0043] Comparative Example 1 The difference from Example 4 is that the alkyl cobalt microspheres prepared in Preparation Example 1.2 were subjected to hydrothermal reaction at 165° C. for 12 hours, and then the CoMS catalyst was prepared by the same method as in Example 4.

[0044] Comparative Example 2 The difference from Example 4 is that the metal organic framework nanoparticles prepared in Preparation Example 2.2 were only subjected to hydrothermal reaction at 165° C. for 12 hours, and then the Co-MOFs catalyst was prepared by the same method as Example 4.

[0045] Application Example 1 An application of a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: First, 5 L of a 10 mg / L papaverine aqueous solution was prepared, and then 0.5 g of the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 1 was added, and then PMS was added, wherein the concentration of PMS in the papaverine aqueous solution was 10 mg / L. The mixture was magnetically stirred at a temperature of 10° C. for 60 minutes.

[0046] Application Example 2 An application of a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: First, 5 L of a 10 mg / L papaverine aqueous solution was prepared, and then 0.5 g of the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 2 was added, and then PMS was added, wherein the concentration of PMS in the papaverine aqueous solution was 10 mg / L. The mixture was magnetically stirred at a temperature of 10° C. for 60 minutes.

[0047] Application Example 3 An application of a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: First, 5 L of a 10 mg / L papaverine aqueous solution was prepared, and then 0.5 g of the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 3 was added, and then PMS was added, wherein the concentration of PMS in the papaverine aqueous solution was 10 mg / L. The mixture was magnetically stirred at a temperature of 10° C. for 60 minutes.

[0048] Application Example 4 An application of a cobalt hydroxide microsphere / metal organic framework composite catalyst comprises the following steps: First, 5 L of a 10 mg / L papaverine aqueous solution was prepared, and then 0.5 g of the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 4 was added, and then PMS was added, wherein the concentration of PMS in the papaverine aqueous solution was 10 mg / L. The mixture was magnetically stirred at a temperature of 10° C. for 60 minutes.

[0049] Comparative application example 1 The difference from Application Example 4 is that: PMS is not added, only the cobalt hydroxide microspheres / metal organic framework composite catalyst prepared in Example 4 is added to the papaverine aqueous solution, and the rest is the same as Application Example 4.

[0050] Comparative Application Example 2 The difference from Application Example 4 is that: no cobalt hydroxide microsphere / metal organic framework composite catalyst is added, only PMS is added to the papaverine aqueous solution, and the rest is the same as Application Example 4.

[0051] Comparative Application Example 3 The difference from Application Example 4 is that the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 4 is replaced by the CoMS catalyst prepared in Comparative Example 1, and the rest is the same as Application Example 4.

[0052] Comparative Application Example 4 The difference from Application Example 4 is that the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in Example 4 is replaced by the Co-MOFs catalyst prepared in Comparative Example 2, and the rest is the same as Application Example 4.

[0053] Performance Testing 1. The concentration of papaverine in the papaverine aqueous solution after treatment for 5 minutes in Application Examples 1-4 and Comparative Application Examples 1-4 was detected by liquid chromatography, and the removal rate of papaverine was calculated. The results are shown in Table 1.

[0054] Table 1 Papaverine removal rate test results Data Analysis: like Figure 1 As shown, Examples 1-4 of the present application prepared cobalt hydroxide microspheres / metal organic framework composite catalysts with a large number of multi-level distributions of internal pore structures. In addition, it can be seen from Table 1 that the removal rate of papaverine in Application Examples 1-4 of the present application is above 85%, which shows that the cobalt hydroxide microspheres / metal organic framework composite catalysts prepared in Examples 1-4 of the present application can effectively catalyze PMS to degrade papaverine in water, and have a better degradation effect on PPCPs in the solution.

[0055] Among them, the removal rate of papaverine in Application Example 3-4 is higher than that in Application Example 1-2, which shows that Example 3-4 further controls the weight ratio of alkyl cobalt microspheres and metal organic framework nanoparticles, which can further improve the effect of the prepared composite catalyst on catalyzing PMS to degrade papaverine in water. In addition, when the weight ratio of alkyl cobalt microspheres and metal organic framework nanoparticles is 1:1, the removal rate of the prepared cobalt hydroxide microsphere / metal organic framework composite catalyst in the PMS excitation system can reach 97.7%, and papaverine has been almost completely degraded within 5 minutes of reaction, which shows that when the weight ratio of alkyl cobalt microspheres and metal organic framework nanoparticles is 1:1, the excitation effect of the prepared composite catalyst on PMS reaches the best level.

[0056] Comparative Application Example 1 only uses a single cobalt hydroxide microsphere / metal organic framework composite catalyst without adding PMS. The removal rate of papaverine within 5 minutes is 12.72%. This shows that since both the cobalt-containing microspheres and the cobalt-containing organic framework compounds have a large specific surface area and pore size, they have a certain adsorption effect on pollutants when used alone, but have no obvious effect on removing pollutants.

[0057] Comparative Application Example 2 uses only PMS without adding cobalt hydroxide microspheres / metal organic framework composite catalyst. Almost no papaverine can be degraded within 5 minutes, and the degradation efficiency is 1.45%. This shows that it is difficult for PMS alone to generate active free radicals by itself. Therefore, materials that can efficiently stimulate it to generate active free radicals must be used in combination with PMS.

[0058] According to the data in Table 1 and combined Figure 2It can be seen that in Comparative Application Example 3, only a single CoMS catalyst was used to excite PMS, and the removal rate of papaverine within 5 minutes was 77.3%, and in Comparative Application Example 4, only a single Co-MOFs catalyst was used to excite PMS, and the removal rate of papaverine within 5 minutes was only 30.01%. Although both materials have a certain papaverine degradation effect, they cannot completely degrade pollutants. Compared with Application Example 4, the removal rate is quite different, which shows that the cobalt hydroxide microsphere / metal organic framework composite catalyst can give full play to the synergistic effect of the two materials CoMS and Co-MOFs, thereby greatly enhancing the system's excitation effect on PMS.

[0059] 1. This application takes Application Example 4 as an example. After a complete reaction in Application Example 4 is completed, the obtained suspension is filtered through a 0.22μm water filter membrane for solid-liquid separation. The recovered solid is ultrasonically washed 3 times with 95% alcohol and ultrapure water respectively to remove the residual by-products of the previous experiment. Finally, it is filtered and separated through a 0.22μm water filter membrane. The recovered solid is dried in an oven at 60°C for 12 hours, and the steps of Application Example 4 are repeated 5 times continuously to test the stability of the material. The results are as follows: Figure 3 shown.

[0060] like Figure 3 As shown, in the second cycle experiment, the removal rate of papaverine by the cobalt hydroxide microsphere / metal organic framework composite catalyst was 81%, in the third cycle experiment, the removal rate of papaverine by the cobalt hydroxide microsphere / metal organic framework composite catalyst was 73%, in the fourth cycle experiment, the removal rate of papaverine by the cobalt hydroxide microsphere / metal organic framework composite catalyst was 71%, and in the fifth cycle experiment, the removal rate of papaverine by the cobalt hydroxide microsphere / metal organic framework composite catalyst was 67%. It can be seen from the experimental data that after multiple cycles, the removal rate of papaverine has decreased. This is mainly because the cobalt in the cobalt-based heterogeneous catalyst used to excite PMS needs to react with PMS to produce active free radicals. It is a self-consumable catalyst. When the concentration of PMS decreases, the degradation effect will also decrease. However, the experimental data show that the system of the present application suppresses the degradation rate of papaverine at a higher level. Therefore, the above results show that the cobalt hydroxide microsphere / metal organic framework composite catalyst prepared in the present application still has a higher degradation effect after multiple cycles, has higher stability, and can be repeatedly applied to water purification.

[0061] The embodiments of this specific implementation method are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A cobalt hydroxide microsphere / metal organic framework composite catalyst, characterized in that: The raw materials used include alkyl cobalt microspheres and metal organic framework nanoparticles; the weight ratio of the alkyl cobalt microspheres to the metal organic framework nanoparticles is 1:(0.1-5.0).

2. A cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 1, characterized in that: The alkyl cobalt microspheres are prepared by the following method: Cobalt nitrate hexahydrate, isopropanol and glycerol are mixed as raw materials, reacted at a temperature of 175-185° C. for 5.5-6.5 hours, and washed and precipitated after solid-liquid separation, dried and ground to obtain alkyl cobalt microspheres.

3. A cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 1, characterized in that: The metal organic framework nanoparticles include one or more of MOF-74 nanoparticles, ZIF-8 nanoparticles, ZIF-67 nanoparticles, and MIL-88A nanoparticles.

4. A cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 3, characterized in that: The metal elements doped in the metal organic framework nanoparticles include one or more of cobalt, iron, manganese and copper.

5. The cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 1, characterized in that: The weight ratio of the alkyl cobalt microspheres to the metal organic framework nanoparticles is 1:(0.5-1.0).

6. A method for preparing the cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 1, characterized in that: The method comprises the following steps: mixing alkyl cobalt microspheres and metal organic framework nanoparticles as raw materials, subjecting the mixture to hydrothermal reaction at a temperature of 135-165° C. for 12 hours, washing the precipitate after solid-liquid separation, and drying the precipitate to obtain a cobalt hydroxide microsphere / metal organic framework composite catalyst.

7. An application of the cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 1, characterized in that: The cobalt hydroxide microsphere / metal organic framework composite catalyst and PMS are added into the EOCs solution, and the temperature of the EOCs solution is not higher than 50° C. and the pH value is greater than 3.

8. The use of a cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 7, characterized in that: The concentration of the EOCs solution is greater than 20 ng / L.

9. The use of a cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 8, characterized in that: 0.01-200 parts by weight of cobalt hydroxide microsphere / metal organic framework composite catalyst is added to each liter of the EOCs solution.

10. The use of a cobalt hydroxide microsphere / metal organic framework composite catalyst according to claim 8, characterized in that: The molar concentration of the PMS in the EOCs solution is 0.08-0.12 mmol / L.

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