Cobalt hydroxide microsphere / metal-organic framework composite catalysts, their preparation methods and applications

Abstract

This application relates to the field of water treatment technology, specifically disclosing a cobalt hydroxide microsphere / metal-organic framework composite catalyst, its preparation method, and its application. The raw materials used in the cobalt hydroxide microsphere / metal-organic framework composite catalyst 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). The composite catalyst prepared in this application has the characteristics of rapidly and efficiently activating PMS in water to generate active free radicals that degrade emerging organic pollutants. Furthermore, it is not easily migrated or transformed in the aquatic environment, and the dissolution rate of the main active substances is extremely low, resulting in minimal environmental harm.

Description

Technical Field

[0001] This application belongs to the field of water treatment technology, specifically relating to the field of activating persulfate degradation of emerging organic pollutants in water, and more specifically, it relates to a cobalt hydroxide microsphere / metal-organic framework composite catalyst and its preparation method and application. Background Technology

[0002] Water is an essential element for human survival. However, approximately 97.5% of the Earth's water is distributed in the oceans, making it unusable. Only about 1% of water resources are available for human use. Therefore, the damage to the water environment caused by human activities to varying degrees cannot be ignored. In recent years, with the increasing production and application of new materials in the agricultural and industrial sectors, human activities have created enormous material wealth. However, this has also led to an increasingly diverse range of pollutants in sewage and wastewater discharges, making water pollution a major challenge to human survival. The composition of pollutants in the aquatic environment is complex, and with the development of analytical chemistry techniques, more and more pollutants are being detected in the aquatic environment. Emerging organic contaminants (EOCs) are particularly worrying. This term includes not only known pollutants but also newly developed compounds that have negative impacts on the environment and human health.

[0003] EOCs originate from hundreds of pollution sources and represent a vast and diverse class of organic compounds, including but not limited to pharmaceuticals and personal care products (PPCPs), pesticides, veterinary drugs, industrially produced compounds and their byproducts, and food additives. These pollutants are highly toxic, have short half-lives, and, coupled with continuous human use, even trace levels can pose significant environmental risks. Since the 1970s, developed countries have constructed numerous public wastewater treatment plants, achieving some success in point source pollution control and improving the quality of human-discharged water. However, because emerging organic pollutants are difficult for the environment to naturally purify, pollutant concentrations in water bodies continue to rise, exacerbating water pollution problems.

[0004] Many organic pollutants (EOCs) are difficult to remove using traditional drinking water and wastewater treatment technologies. To remove EOCs from contaminated water, various technologies have been developed, including adsorption and advanced oxidation processes (AOPs). Among these, adsorption technologies, using 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 drawbacks, including: 1) these technologies cannot degrade EOCs to achieve detoxification; 2) the regeneration cost of adsorbents is high, and they typically require expensive and toxic organic solvents, generating large amounts of residual regeneration waste, necessitating additional costly treatment and disposal. Therefore, developing new and efficient processes for treating EOCs has become a research hotspot.

[0005] Advanced oxidation processes (AOPs) are an oxidation technology developed in the 1980s, primarily used for the treatment of recalcitrant organic pollutants. Due to their high degradation efficiency and strong deep treatment capabilities, they have always been a highly regarded technology in wastewater treatment. The traditional concept of AOPs was proposed by Glaze et al. in 1987: an oxidation technology that utilizes the highly oxidizing hydroxyl radicals (·OH) generated during the reaction to oxidize, decompose, and even mineralize organic pollutants. ·OH has a high standard redox potential (E0 = 1.8-2.7V), capable of degrading most organic pollutants, transforming them into low-toxicity, easily biodegradable small molecules, or even directly mineralizing them into inorganic substances.

[0006] As research deepens, various advanced oxidation technologies derived from traditional theories are emerging. Among them, methods based on sulfate radicals are particularly favored by researchers due to their advantages such as rapid degradation, good pH adaptability, and high mineralization degree. The core of sulfate radical advanced oxidation technology is the activation of persulfates (permonosulfate (PMS) and perdisulfate (PDS)). PMS, due to its highly asymmetric molecular structure, is more easily activated to generate sulfate radicals than PDS. Current research shows that transition metals can catalyze the generation of sulfate radicals from PMS. However, transition metals are usually used in large quantities when catalyzing PMS, and excessive amounts of transition metals, while catalyzing PMS, are also heavy metal pollutants, causing secondary pollution to water bodies. Summary of the Invention

[0007] To address the aforementioned technical problems, this application provides a cobalt hydroxide microsphere / metal-organic framework composite catalyst and its preparation method, and applies it to efficiently excite PMS in water to generate active free radicals ·OH and / or SO4. -• Utilizing highly reactive free radicals to oxidize, decompose, or even mineralize emerging organic pollutants. These emerging organic pollutants include, but are not limited to, pharmaceuticals and personal care products (PPCPs), antibiotics / resistance genes, and perfluorinated / polyfluorinated alkyl compounds (PFAS).

[0008] In the first aspect, this application provides a cobalt hydroxide microsphere / metal-organic framework composite catalyst, which adopts the following technical solution:

[0009] A cobalt hydroxide microsphere / metal-organic framework composite catalyst, the raw materials of which 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).

[0010] More specifically, the alkylcobalt microspheres are prepared by the following method:

[0011] Cobalt nitrate hexahydrate, isopropanol, and glycerol were mixed as raw materials and reacted at 175-185℃ for 5.5-6.5 hours. After solid-liquid separation, the precipitate was washed, dried, and ground to obtain alkyl cobalt microspheres.

[0012] 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.

[0013] More specifically, the metal-organic framework nanoparticles are doped with one or more of the following metal elements: cobalt, iron, manganese, and copper.

[0014] In this application, the inventors describe cobalt-doped MOF-74 nanoparticles (Co-MOF-74-NP) as metal-organic framework nanoparticles.

[0015] The Co-MOF-74-NP was prepared by the following method:

[0016] Cobalt(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.

[0017] In this application, the mixing of the raw materials can be achieved by means of stirring and / or ultrasonic dispersion, which are known to those skilled in the art.

[0018] The solid-liquid separation is achieved by means of centrifugation and / or vacuum filtration, which are known to those skilled in the art. If vacuum filtration is used, a 0.22 μm organic filter membrane and / or water membrane is used.

[0019] The washing process involves using the same solvents as those used when processing synthetic materials, washing 1-3 times, and then washing with ultrapure water until neutral.

[0020] The drying conditions were all: drying at 60-80℃ for 12 hours.

[0021] Through the above technical solution, this application uses alkyl cobalt microspheres (s-CoA) and metal-organic framework nanoparticles (MOF-NP) as raw materials to prepare a cobalt hydroxide microsphere / metal-organic framework (CoMS / MOFs) composite catalyst under certain temperature and time conditions. The catalyst uses a metal-organic framework as a support, with cobalt hydroxide microspheres loaded on the metal-organic framework support. Because the alkyl cobalt microspheres and metal-organic framework nanoparticles can be firmly bonded together during the hydrothermal reaction, the CoMS / MOFs composite catalyst prepared in this application is not easily migrated or transformed in the aqueous environment, and the dissolution rate of the main active substances is extremely low, resulting in minimal environmental harm. Simultaneously, the CoMS / MOFs composite catalyst also exhibits good settling performance, allowing for rapid separation from water after use. Simple filtration and washing can achieve green, pollution-free, low-energy, and rapid regeneration of the catalyst, and it also exhibits high stability, enabling continuous multiple cycles of pollutant degradation and material regeneration.

[0022] Furthermore, the CoMS / MOFs composite catalyst prepared in this application can fully leverage the synergistic effect of CoMS and MOFs, and has a large number of multi-level distributions of internal pore structures, a large specific surface area, a significant capillary effect, excellent ion exchange performance, diverse surface functional groups, and abundant active sites. Therefore, it has the effect of rapidly and efficiently stimulating PMS to generate active free radicals to degrade new organic pollutants in water.

[0023] Preferably, the weight ratio of the alkyl cobalt microspheres to the metal-organic framework nanoparticles is 1:(0.5-1.0).

[0024] Alkylcobalt microspheres and metal-organic framework nanoparticles can be firmly bonded together in hydrothermal reactions, fully leveraging the synergistic effect between the two materials. This allows the prepared CoMS / MOFs composite catalyst to efficiently stimulate PMS to generate active free radicals. Since cobalt hydroxyl is the main active substance in the entire catalyst, this application further optimizes the ratio between alkylcobalt microspheres and metal-organic framework nanoparticles through the above technical solution. This results in a relatively high proportion of CoMS in the prepared composite catalyst, which can be more fully loaded onto MOFs, further improving the activation ability of the CoMS / MOFs composite catalyst for PMS, thereby enhancing the degradation effect. Experimental data show that when the weight ratio of alkylcobalt microspheres to metal-organic framework nanoparticles is 1:1, the prepared CoMS / MOFs composite catalyst exhibits the strongest activation ability for PMS and the best degradation effect on emerging organic pollutants in water.

[0025] Secondly, this application provides a method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst, which employs the following technical solution:

[0026] A method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps: mixing alkyl cobalt microspheres and metal-organic framework nanoparticles as raw materials, hydrothermally reacting them at 135-165℃ for 12 hours, washing the precipitate after solid-liquid separation, and drying to obtain the cobalt hydroxide microsphere / metal-organic framework composite catalyst.

[0027] Thirdly, the application of the cobalt hydroxide microsphere / metal-organic framework composite catalyst provided in this application adopts the following technical solution:

[0028] An application of a cobalt hydroxide microsphere / metal-organic framework composite catalyst involves adding the cobalt hydroxide microsphere / metal-organic framework composite catalyst and PMS together into an EOCs solution, wherein the temperature of the EOCs solution is not higher than 50°C and the pH value is greater than 3.

[0029] More specifically, the concentration of the EOCs solution is greater than 20 ng / L.

[0030] More specifically, 0.01-200 parts by weight of cobalt hydroxide microspheres / metal-organic framework composite catalyst are added to each liter of the EOCs solution.

[0031] More specifically, the molar concentration of PMS in the EOCs solution is 0.8-1.2 mmol / L.

[0032] Through the above technical solution, this application adds a certain amount of CoMS / MOFs composite catalyst and PMS together to an EOCs solution of a certain concentration, which can stably and efficiently catalyze the degradation of EOCs in water by PMS, effectively removing EOCs pollutants from the solution. In this application, the inventors use an EOCs solution concentration of 10 mg / L, a PMS molar concentration of 0.1 mmol / L in the EOCs solution, and 0.1 g of CoMS / MOFs composite catalyst added per liter of the EOCs solution as an example for illustration.

[0033] The applications of this application include, but are not limited to, drinking water treatment, domestic sewage treatment, hospital wastewater treatment, livestock wastewater treatment, industrial wastewater treatment, landfill leachate treatment, groundwater remediation, and emergency treatment of natural water pollution. In different application scenarios, the contact mode between the cobalt hydroxide microspheres / metal-organic framework composite catalyst and the water to be treated varies.

[0034] Specifically, the steps in water treatment processes such as drinking water treatment, domestic sewage treatment, hospital sewage treatment, livestock wastewater treatment, industrial wastewater treatment, and landfill leachate treatment are as follows:

[0035] a. For some industrial wastewater and landfill leachate, it is necessary to set up wastewater cooling tanks and wastewater pH adjustment tanks to adjust and homogenize the wastewater temperature and pH value, so that the wastewater temperature does not exceed 50℃ and the pH value is greater than 3.

[0036] b. The reaction tower is filled with the cobalt hydroxide microspheres / metal-organic framework composite catalyst, and water and PMS solution are continuously pumped into the reaction tower using a water pump. The water after the pollutants have reacted is discharged.

[0037] In water treatment processes such as groundwater remediation and emergency treatment of natural water pollution, the steps are as follows:

[0038] a. The cobalt hydroxide microspheres / metal-organic framework composite catalyst is loaded into SMS non-woven fabric bags (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 odorless, highly efficient in preventing bacteria, high strength, and good filtration performance), and then placed in the water body to be repaired or treated in an emergency through a well or other means.

[0039] b. Add PMS to the water body to be remediated according to the required concentration for in-situ restoration;

[0040] c. Regularly test water quality and replenish PMS in the water as needed.

[0041] In summary, this application has the following beneficial technical effects:

[0042] 1. The CoMS / MOFs composite catalyst prepared in this application has the characteristics of rapidly and efficiently activating PMS in water to generate active free radicals that degrade emerging organic pollutants;

[0043] 2. The CoMS / MOFs composite catalyst prepared in this application is not easily migrated and transformed in the aqueous environment, and the dissolution rate of the main active substances is extremely low, resulting in less environmental harm.

[0044] 3. The CoMS / MOFs composite catalyst prepared in this application has good settling performance, can be separated from water in a short time after use, and can be regenerated in a green, pollution-free, low-consumption and rapid manner through simple filtration and washing.

[0045] 4. The CoMS / MOFs composite catalyst prepared in this application has high stability and can be continuously cycled for pollutant degradation and material regeneration multiple times. Attached Figure Description

[0046] Figure 1 These are transmission electron microscope (TEM) images of the CoMS / MOFs composite catalysts prepared in Examples 1-4 of this application;

[0047] Figure 2 These are graphs showing the degradation effect of papaverine in Application Example 4 and Comparative Application Examples 3-4 of this application;

[0048] Figure 3 This application uses Example 4 as an example to illustrate the effect of repeated experiments on the degradation of papaverine in water. Detailed Implementation

[0049] The present application will be further described in detail below with reference to the accompanying drawings, embodiments and application examples.

[0050] The EOCs solutions of this application include, but are not limited to, pharmaceutical and personal care products (PPCPs), antibiotics / resistance genes, and perfluorinated / polyfluoroalkyl compounds (PFAS). In specific embodiments of this application, a PPCPs solution is used as an example. The PPCPs solution can be a solution containing various antibiotics, synthetic musk, analgesics, antihypertensive drugs, contraceptives, hypnotics, weight-loss drugs, hairspray, hair dye, and bactericides. More specifically, this application uses an aqueous solution containing papaverine as an example, where the concentration of papaverine in the solution is 10 mg / L and the pH is neutral.

[0051] Unless otherwise specified, all raw materials used in this application are commercially available products. Among them, the alkyl cobalt microspheres and cobalt-doped metal-organic framework nanoparticles were prepared by the following methods:

[0052] Preparation Example 1.1

[0053] The preparation method of alkyl cobalt microspheres includes the following steps:

[0054] 10 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was dispersed and dissolved in 60 mL of isopropanol, and then 16 mL of glycerol was added. The mixture was magnetically stirred for 30 minutes until completely dissolved. The mixture was then 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 the precipitate was washed three times with ethanol. The product was then dried at 60 °C for 12 hours and ground to obtain alkyl cobalt microspheres.

[0055] Preparation Example 1.2

[0056] The preparation method of alkyl cobalt microspheres includes the following steps:

[0057] 10 mmol of cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was dispersed and dissolved in 60 mL of isopropanol, and then 16 mL of glycerol was added. The mixture was magnetically stirred for 30 minutes until completely dissolved. The mixture was then 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 the precipitate was washed three times with ethanol. The product was then dried at 80 °C for 12 hours and ground to obtain alkyl cobalt microspheres.

[0058] Preparation Example 2.1

[0059] A method for preparing cobalt-doped metal-organic framework nanoparticles includes the following steps:

[0060] 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 methanol solution containing 0.75 mmol of 2,5-dihydroxyterephthalic acid was added dropwise and mixed. The mixture was stirred at room temperature for 2 hours. The product was separated into solid and liquid phases using a 0.22 μm organic filter membrane. The precipitate was washed once with methanol and then twice with ultrapure water. It was dried at 60 °C for 12 hours and then ground to obtain Co-MOF-74-NP.

[0061] Preparation Example 2.2

[0062] A method for preparing cobalt-doped metal-organic framework nanoparticles includes the following steps:

[0063] 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 methanol solution containing 0.75 mmol of 2,5-dihydroxyterephthalic acid was added dropwise and mixed. The mixture was stirred at room temperature for 3 hours. The product was separated into solid and liquid phases using a 0.22 μm organic filter membrane. The precipitate was washed once with methanol and then twice with ultrapure water. It was dried at 80 °C for 12 hours and then ground to obtain Co-MOF-74-NP.

[0064] Example 1

[0065] A method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0066] 10g of alkyl cobalt microspheres prepared in Preparation Example 1.1 and 1g of metal-organic framework nanoparticles prepared in Preparation Example 2.1 were stirred and mixed, and then hydrothermally reacted at 135°C for 12 hours. The product was separated into solid and liquid phases using a 0.22μm organic filter membrane, 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.

[0067] Example 2

[0068] A method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0069] 10g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 50g of the metal-organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then hydrothermally reacted at 165°C for 12 hours. The product was separated into solid and liquid phases using a 0.22μm organic filter membrane, washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain the cobalt hydroxide microsphere / metal-organic framework composite catalyst.

[0070] Example 3

[0071] A method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0072] 10g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 5g of the metal-organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then hydrothermally reacted at 165°C for 12 hours. The product was separated into solid and liquid phases using a 0.22μm organic filter membrane, washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain the cobalt hydroxide microsphere / metal-organic framework composite catalyst.

[0073] Example 4

[0074] A method for preparing a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0075] 10g of the alkyl cobalt microspheres prepared in Preparation Example 1.2 and 10g of the metal-organic framework nanoparticles prepared in Preparation Example 2.2 were stirred and mixed, and then hydrothermally reacted at 165°C for 12 hours. The product was separated into solid and liquid phases using a 0.22μm organic filter membrane, washed once with methanol, then washed twice with ultrapure water, and dried at 60°C for 12 hours to obtain the cobalt hydroxide microsphere / metal-organic framework composite catalyst.

[0076] Comparative Example 1

[0077] The difference from Example 4 is that the alkyl cobalt microspheres prepared in Preparation Example 1.2 were hydrothermally reacted at 165°C for 12 hours alone, and then the CoMS catalyst was prepared using the same method as in Example 4.

[0078] Comparative Example 2

[0079] The difference from Example 4 is that the metal-organic framework nanoparticles prepared in Preparation Example 2.2 were hydrothermally reacted at 165°C for 12 hours alone, and then the Co-MOF catalyst was prepared by the same method as in Example 4.

[0080] Application Example 1

[0081] The application of a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0082] First, prepare 5L of papaverine aqueous solution with a concentration of 10mg / L, then add 0.5g of the cobalt hydroxide microsphere / metal-organic framework composite catalyst prepared in Example 1, and then add PMS with a concentration of 10mg / L in the papaverine aqueous solution. Stir magnetically for 60 minutes at 10°C.

[0083] Application Example 2

[0084] The application of a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0085] First, prepare 5L of papaverine aqueous solution with a concentration of 10mg / L, then add 0.5g of the cobalt hydroxide microsphere / metal-organic framework composite catalyst prepared in Example 2, and then add PMS with a concentration of 10mg / L in the papaverine aqueous solution. Stir magnetically for 60 minutes at 10°C.

[0086] Application Example 3

[0087] The application of a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0088] First, prepare 5L of papaverine aqueous solution with a concentration of 10mg / L, then add 0.5g of the cobalt hydroxide microsphere / metal-organic framework composite catalyst prepared in Example 3, and then add PMS with a concentration of 10mg / L in the papaverine aqueous solution. Stir magnetically for 60 minutes at 10°C.

[0089] Application Example 4

[0090] The application of a cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps:

[0091] First, prepare 5L of papaverine aqueous solution with a concentration of 10mg / L, then add 0.5g of the cobalt hydroxide microsphere / metal-organic framework composite catalyst prepared in Example 4, and then add PMS with a concentration of 10mg / L in the papaverine aqueous solution. Stir magnetically for 60 minutes at 10°C.

[0092] Comparative Application Example 1

[0093] 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. Everything else is the same as in Application Example 4.

[0094] Comparative Application Example 2

[0095] The difference from Application Example 4 is that no cobalt hydroxide microspheres / metal-organic framework composite catalyst was added; only PMS was added to the papaverine aqueous solution. Everything else was the same as in Application Example 4.

[0096] Comparative Application Example 3

[0097] The difference from Application Example 4 is that the cobalt hydroxide microspheres / metal-organic framework composite catalyst prepared in Example 4 was replaced with the CoMS catalyst prepared in Comparative Example 1, and all other aspects were the same as in Application Example 4.

[0098] Comparative Application Example 4

[0099] The difference from Application Example 4 is that the cobalt hydroxide microspheres / metal-organic framework composite catalyst prepared in Example 4 was replaced with the Co-MOFs catalyst prepared in Comparative Example 2, and all other aspects were the same as in Application Example 4.

[0100] Performance testing

[0101] 1. The concentration of papaverine in the aqueous solution of papaverine 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.

[0102] Table 1. Results of papaverine removal rate detection

[0103]

[0104]

[0105] Data Analysis:

[0106] like Figure 1 As shown, Examples 1-4 of this application prepared cobalt hydroxide microspheres / metal-organic framework composite catalysts with a large number of hierarchically distributed internal pore structures. Furthermore, as can be seen from Table 1, the papaverine removal rate of Examples 1-4 of this application is above 85%, indicating that the cobalt hydroxide microspheres / metal-organic framework composite catalysts prepared in Examples 1-4 of this application can effectively catalyze the degradation of papaverine in water by PMS, and have a better degradation effect on PPCPs in solution.

[0107] Among them, the papaverine removal rate of Application Examples 3-4 was higher than that of Application Examples 1-2. This indicates that further controlling the weight ratio of alkylcobalt microspheres and metal-organic framework nanoparticles in Examples 3-4 can further improve the effect of the prepared composite catalyst on the degradation of papaverine in water by PMS. Furthermore, when the weight ratio of alkylcobalt microspheres to metal-organic framework nanoparticles was 1:1, the removal rate of the prepared cobalt hydroxide microsphere / metal-organic framework composite catalyst in the PMS system reached 97.7%, and papaverine was almost completely degraded within 5 minutes of the reaction. This shows that when the weight ratio of alkylcobalt microspheres to metal-organic framework nanoparticles was 1:1, the composite catalyst achieved the optimal activation effect on PMS.

[0108] In contrast, Application Example 1, which used only cobalt hydroxide microspheres / metal-organic framework composite catalyst without the addition of PMS, showed a removal rate of 12.72% for papaverine within 5 minutes. This indicates that since both cobalt-containing microspheres and cobalt-containing organic framework compounds have large specific surface areas and pore sizes, they can be used alone to adsorb pollutants to a certain extent, but they do not have a significant effect on removing pollutants.

[0109] In contrast, Application Example 2, which uses PMS alone without adding cobalt hydroxide microspheres / metal-organic framework composite catalyst, shows that almost no papaverine can be degraded within 5 minutes, with a degradation efficiency of 1.45%. This indicates that PMS alone is difficult to generate active free radicals on its own. Therefore, it is necessary to use materials that can efficiently stimulate the generation of active free radicals to mix and use with PMS.

[0110] Based on the data in Table 1 and in conjunction with... Figure 2As can be seen, compared with Application Example 3, which used only CoMS catalyst to activate PMS, the removal rate of papaverine was 77.3% within 5 minutes. In contrast, compared with Application Example 4, which used only Co-MOF catalyst to activate PMS, the removal rate of papaverine was only 30.01% within 5 minutes. Although both materials have a certain papaverine degradation effect, they cannot completely degrade the pollutant. The removal rate is significantly different compared with Application Example 4. This indicates that the cobalt hydroxide microsphere / metal-organic framework composite catalyst can give full play to the synergistic effect of CoMS and Co-MOF, thereby greatly enhancing the activation effect of the system on PMS.

[0111] 1. Taking Application Example 4 as an example, after a complete reaction in Application Example 4, the resulting suspension was filtered through a 0.22 μm aqueous filter membrane for solid-liquid separation. The recovered solid was ultrasonically washed three times each with 95% alcohol and ultrapure water to remove residual byproducts from the previous experiment. Finally, it was filtered again through a 0.22 μm aqueous filter membrane. The recovered solid was dried in an oven at 60°C for 12 hours. The steps of Application Example 4 were repeated five times consecutively to test the stability of the material. The results are as follows: Figure 3 As shown.

[0112] 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 was 73%; in the fourth cycle experiment, the removal rate was 71%; and in the fifth cycle experiment, the removal rate was 67%. The experimental data show that the removal rate of papaverine decreased after multiple cycles. This is mainly because the cobalt in the cobalt-based heterogeneous catalyst used to activate PMS needs to react with PMS to generate active free radicals, making it a self-consuming catalyst. When the concentration of PMS decreases, the degradation effect also decreases. However, the experimental data indicates that the degradation rate inhibition of papaverine by the system in this application remains at a high level. Therefore, the above results show that the cobalt hydroxide microsphere / metal-organic framework composite catalyst prepared in this application still has a high degradation effect and high stability after multiple cycles, and can be repeatedly applied to water purification.

[0113] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this 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). The alkylcobalt microspheres were prepared by the following method: Cobalt nitrate hexahydrate, isopropanol, and glycerol were mixed as raw materials and reacted at 175-185℃ for 5.5-6.5 hours. After solid-liquid separation, the precipitate was washed, dried, and ground to obtain alkyl cobalt microspheres. The metal-organic framework nanoparticles include one or more of MOF-74 nanoparticles, ZIF-8 nanoparticles, ZIF-67 nanoparticles, and MIL-88A nanoparticles; The preparation method of the cobalt hydroxide microsphere / metal-organic framework composite catalyst includes the following steps: alkyl cobalt microspheres and metal-organic framework nanoparticles are mixed as raw materials, and then hydrothermally reacted at a temperature of 135-165℃ for 12 hours. After solid-liquid separation, the precipitate is washed and dried to obtain the cobalt hydroxide microsphere / metal-organic framework composite catalyst.

2. 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).

3. The 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 were added together to the EOCs solution, and the temperature of the EOCs solution was not higher than 50°C and the pH value was greater than 3.

4. The application of the cobalt hydroxide microsphere / metal-organic framework composite catalyst according to claim 3, characterized in that, The concentration of the EOCs solution is greater than 20 ng / L.

5. The application of the cobalt hydroxide microsphere / metal-organic framework composite catalyst according to claim 4, characterized in that, 0.01-200 parts by weight of cobalt hydroxide microspheres / metal-organic framework composite catalyst are added to each liter of the EOCs solution.

6. The application of the cobalt hydroxide microsphere / metal-organic framework composite catalyst according to claim 4, characterized in that, The molar concentration of PMS in the EOCs solution is 0.08-0.12 mmol / L.

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