Magnetic cobalt-copper-based catalyst, preparation method thereof, and application in wastewater treatment

Abstract

The present invention belongs to the field of material preparation and environmental pollution control, and in particular to a magnetic cobalt-copper-based catalyst, its preparation method and its application in treating wastewater. The preparation method comprises the following steps: mixing a methanol solution of Fe3O4 nanoparticles and 2-methylimidazole with a methanol solution of cobalt nitrate hexahydrate, collecting the precipitate with a magnet and washing and drying to obtain a magnetic template; adding an ethanol solution of copper nitrate hexahydrate to the ethanol solution of the magnetic template, ultrasonically reacting, collecting the product with a magnet, and washing to obtain Fe3O4@Co‑Cu LDH; calcining Fe3O4@Co‑Cu LDH to obtain a magnetic cobalt-copper-based catalyst. The magnetic cobalt-copper-based catalyst prepared by the present invention has magnetism, is rich in oxygen vacancies, can produce highly active singlet oxygen during degradation, has high catalytic activity, stability and recyclability, and is almost unaffected by inorganic anions in water during the degradation process.

Description

Technical Field

[0001] The invention belongs to the field of material preparation and environmental pollution control, and particularly relates to a magnetic cobalt-copper-based catalyst, a preparation method thereof, and application in treating wastewater. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] A large number of antiviral drugs are used in clinical treatment, which has led to concerns about the pollution of water bodies in the environment caused by the use of antiviral drugs. It is necessary to develop a technology that can effectively degrade antiviral drugs in wastewater.

[0004] In recent years, the use of activated persulfate to degrade refractory organic pollutants in wastewater has received widespread attention. Improving the activation efficiency is the key to improving the treatment effect of pollutants. The activation of persulfate can be divided into two types: free radical oxidation pathway and non-free radical oxidation pathway. The free radical oxidation pathway refers to the use of different technologies to activate persulfate to produce sulfate radicals. and hydroxyl radicals (HO · ) etc., thereby quickly and efficiently degrading pollutants; the non-radical oxidation pathway mainly utilizes persulfate activation to produce some non-radical oxidizing substances (such as singlet oxygen 1 O2) to achieve rapid degradation of pollutants. In addition, the non-radical process involving singlet oxygen can improve oxidation selectivity and reduce the production of dangerous by-products.

[0005] Catalysts can effectively activate persulfate. However, in heterogeneous degradation systems, catalyst separation and recovery are difficult, limiting their practical application. Furthermore, the catalysts' inherently weak performance and stability, as well as their limited anti-interference capabilities, also limit the efficiency of persulfate activation and degradation. Summary of the Invention

[0006] To address the deficiencies of the prior art, the present invention provides a magnetic cobalt-copper-based catalyst, a preparation method thereof, and its use in wastewater treatment. The magnetic cobalt-copper-based catalyst prepared by the present invention exhibits magnetic properties, is rich in oxygen vacancies, generates highly active singlet oxygen during degradation, exhibits high catalytic activity, stability, and recyclability, and is virtually unaffected by inorganic anions in water during the degradation process.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a magnetic cobalt-copper-based catalyst, comprising the following steps:

[0009] S1, mixing Fe3O4 nanoparticles and a methanol solution of 2-methylimidazole with a methanol solution of cobalt nitrate hexahydrate, collecting the precipitate with a magnet, washing and drying it, to obtain a magnetic template;

[0010] S2, adding the ethanol solution of copper nitrate hexahydrate to the ethanol solution of the magnetic template, ultrasonically reacting, collecting the product with a magnet, and washing to obtain Fe3O4@Co-Cu LDH;

[0011] S3. Calcinate Fe3O4@Co-Cu LDH to obtain a magnetic cobalt-copper-based catalyst.

[0012] Among the catalysts for activating persulfate, layered double hydroxides (LDHs) have been widely used in recent years. Compared with LDHs, their calcined products, layered double oxides (LDOs), are rich in oxygen vacancies, have larger specific surface area, stronger stability and faster redox rate. 1 O2) as an excited active oxygen produced by activated persulfate plays an important role in the degradation of organic pollutants. In addition, the oxygen vacancies (Ov) generated by the separation of oxygen in the catalyst lattice enable the organic pollutants to have a faster degradation efficiency.

[0013] Preferably, the method for preparing Fe3O4 particles comprises the following steps:

[0014] After ferric chloride hexahydrate is dissolved in ethylene glycol, polyethylene glycol and sodium acetate are added to the solution and stirred to obtain a mixed solution, the mixed solution is subjected to a hydrothermal reaction, and after the reaction, the Fe3O4 nanoparticles are finally obtained by magnetic separation, water washing, alcohol washing, and drying.

[0015] Further preferably, the concentration of ferric chloride hexahydrate in the mixed solution is 0.12-0.13 mol / L, the concentration of polyethylene glycol is 20-30 g / L, and the concentration of sodium acetate is 85-95 g / L.

[0016] More preferably, the temperature of the hydrothermal reaction is 190-210° C., and the time is 16-24 h.

[0017] Preferably, in step S1, the concentration of Fe3O4 nanoparticles in the methanol solution of Fe3O4 nanoparticles and 2-methylimidazole is 0.4-0.6 g / L, the concentration of 2-methylimidazole is 35-45 g / L, the concentration of cobalt nitrate hexahydrate in the methanol solution of cobalt nitrate hexahydrate is 40-50 g / L, the volume ratio of the methanol solution of Fe3O4 nanoparticles and 2-methylimidazole to the methanol solution of cobalt nitrate hexahydrate is 1:0.9-1.1, and the stirring time is 20-28 h.

[0018] Preferably, in step S2, the concentration of the ethanol solution of copper nitrate hexahydrate is 5-20 g / L, the concentration of the ethanol solution of the magnetic template is 1.4-1.6 g / L, the volume ratio of the ethanol solution of copper nitrate hexahydrate to the ethanol solution of the magnetic template is 0.3-0.5:1, and the ultrasonic reaction time is 30-90 min.

[0019] Preferably, in step S3, the calcination temperature is 250-350° C. and the calcination time is 2.5-3.5 h.

[0020] In a second aspect, the present invention provides a magnetic cobalt-copper-based catalyst obtained by the preparation method described in the first aspect. The magnetic cobalt-copper-based catalyst, Fe3O4@Co-Cu LDO, has the advantages of large specific surface area, uniform distribution, and easy magnetic separation. The nanoparticles have a particle size of 100-500 nm.

[0021] In a third aspect, the present invention provides the use of the magnetic cobalt-copper-based catalyst as described in the second aspect in treating wastewater, characterized in that it catalyzes the degradation of organic matter in the wastewater in a persulfate system.

[0022] Preferably, the organic matter includes a drug, and the drug includes at least one of famciclovir, acyclovir, lamivudine and favipiravir.

[0023] In a fourth aspect, the present invention provides a method for treating organic matter in wastewater, comprising adding the magnetic cobalt-copper-based catalyst and persulfate as described in the second aspect to wastewater containing organic matter to treat the wastewater.

[0024] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0025] The magnetic cobalt-copper-based catalyst Fe3O4@Co-Cu LDO prepared by the present invention has Fe3O4 as the core to provide magnetism. The Fe3O4@Co-Cu LDO formed by calcination has a large specific surface area and is rich in oxygen vacancies. It can produce highly active singlet oxygen during degradation, has high catalytic activity, stability and recyclability, and is almost unaffected by inorganic anions in water during the degradation process.

[0026] The magnetic cobalt-copper based catalyst Fe3O4@Co-Cu LDO of the present invention contains oxygen vacancies and can produce a large amount of 1 O2 makes the non-free radical process accompany the entire catalytic degradation process, improves the selective oxidation and reduces the generation of by-products.

[0027] The magnetic cobalt-copper-based catalyst Fe3O4@Co-Cu LDO of the present invention can effectively degrade antiviral drugs such as famciclovir, acyclovir, lamivudine and favipiravir, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] Figure 1 XRD patterns of Fe3O4@Co-Cu LDO of Examples 1(a), 2(b), 3(c) and 4(d);

[0030] Figure 2 This is the SEM image of Fe3O4@Co-Cu LDO of Example 3;

[0031] Figure 3 The degradation diagram of FCV under persulfate activation by Fe3O4@Co-Cu LDO of Example 3 with different dosages;

[0032] Figure 4 This is the degradation diagram of Fe3O4@Co-Cu LDO activated with persulfate to different concentrations of FCV in Example 3;

[0033] Figure 5 The recycling performance of Fe3O4@Co-Cu LDO in Example 3;

[0034] Figure 6 The Fe3O4@Co-Cu LDO of Example 3 activates persulfate to produce (a) sulfate radicals, hydroxyl radicals and (b) singlet oxygen 1 O2 detection;

[0035] Figure 7 This is a graph showing the effects of sulfate and humic acid in persulfate activated by Fe3O4@Co-Cu LDO on FCV degradation in Example 3;

[0036] Figure 8 This is the degradation diagram of different pharmaceutical pollutants by Fe3O4@Co-Cu LDO activated persulfate in Example 3. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0038] Example 1

[0039] Preparation of Fe3O4@Co-Cu LDO

[0040] 1) Preparation of Fe3O4 nanoparticles

[0041] Dissolve 1.35 g (5 mmol) of FeCl₃·6H₂O in 40 mL of ethylene glycol, add 1.0 g of polyethylene glycol, and sonicate for 90 minutes until completely dissolved. Finally, add 3.6 g of CH₃COONa. Stir the mixture with magnetic stirring at room temperature for 30 minutes, then transfer it to a 50 mL polytetrafluoroethylene autoclave, heat it to 200°C in an oven, hold it for 20 hours, and cool it to room temperature. The resulting black product is washed several times with ultrapure water and anhydrous ethanol, then dried at 60°C for 24 hours.

[0042] 2) Preparation of magnetic template

[0043] 0.06g of Fe₃O₄ particles and 4.8g of 2-methylimidazole (2-MeIM) were added to 120mL of methanol and sonicated to form Solution A. 5.4g of Co(NO₃)₂·6H₂O was dissolved in 120mL of methanol to form Solution B. Solutions A and B were rapidly mixed and stirred at room temperature for 24 hours. The resulting purple precipitate of the magnetic template was collected with a magnet, washed several times with ethanol, and then dried at 70°C for 24 hours.

[0044] 3) Preparation of Fe3O4@Co-Cu LDH

[0045] 0.15g of the magnetic template was added to 100mL of ethanol and dispersed evenly to form suspension A. 0.2g of Cu(NO3)2·6H2O was then added to 40mL of ethanol and sonicated to form solution B. Solution B was quickly added to solution A at room temperature and sonicated for 50 minutes. The resulting material was collected with a magnet, washed several times with ethanol, and dried in a vacuum oven at 60°C for 24 hours to obtain Fe3O4@Co-Cu LDH.

[0046] 4) Preparation of Fe3O4@Co-Cu LDO

[0047] The prepared Fe3O4@Co-Cu LDH was evenly dispersed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain Fe3O4@Co-Cu LDO. Its catalytic performance was tested.

[0048] Example 2

[0049] Preparation of Fe3O4@Co-Cu LDO

[0050] 1) Preparation of Fe3O4@Co-Cu LDH

[0051] The magnetic template was prepared as in Example 1. 0.15 g of the magnetic template was added to 100 mL of ethanol and dispersed evenly to form suspension A. 0.4 g of Cu(NO₃)₂·6H₂O was then added to 40 mL of ethanol and sonicated to form solution B. Solution B was quickly added to solution A at room temperature and sonicated for 30 minutes. The resulting material was collected using a magnet and washed several times with ethanol. The mixture was then dried in a vacuum oven at 60°C for 24 hours to obtain Fe₃O₄@Co-Cu LDH.

[0052] 2) Preparation of Fe3O4@Co-Cu LDO

[0053] The prepared Fe3O4@Co-Cu LDH was evenly dispersed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain Fe3O4@Co-Cu LDO. Its catalytic performance was tested.

[0054] Example 3

[0055] Preparation of Fe3O4@Co-Cu LDO

[0056] 1) Preparation of Fe3O4@Co-Cu LDH

[0057] The magnetic template was prepared as in Example 1. 0.15 g of the magnetic template was added to 100 mL of ethanol and dispersed evenly to form suspension A. 0.6 g of Cu(NO₃)₂·6H₂O was then added to 40 mL of ethanol and sonicated to form solution B. Solution B was quickly added to solution A at room temperature and sonicated for 70 minutes. The resulting material was collected using a magnet and washed several times with ethanol. The mixture was then dried in a vacuum oven at 60°C for 24 hours to obtain Fe₃O₄@Co-Cu LDH.

[0058] 2) Preparation of Fe3O4@Co-Cu LDO

[0059] The prepared Fe3O4@Co-Cu LDH was evenly dispersed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain Fe3O4@Co-Cu LDO. Its catalytic performance was tested.

[0060] Example 4

[0061] Preparation of Fe3O4@Co-Cu LDO

[0062] 1) Preparation of the magnetic template: 0.15 g of the magnetic template was added to 100 mL of ethanol and dispersed evenly to form suspension A. 0.8 g of Cu(NO₃)₂·6H₂O was then added to 40 mL of ethanol and sonicated to form solution B. Solution B was rapidly added to solution A at room temperature and sonicated for 90 minutes. The resulting material was collected using a magnet and washed several times with ethanol. The mixture was then dried in a vacuum oven at 60°C for 24 hours to obtain Fe₃O₄@Co-Cu LDH.

[0063] 2) Preparation of Fe3O4@Co-Cu LDO

[0064] The prepared Fe3O4@Co-Cu LDH was evenly dispersed in a crucible and calcined in a muffle furnace at 300°C for 3 h to obtain Fe3O4@Co-Cu LDO. Its catalytic performance was tested.

[0065] The XRD patterns of Fe3O4@Co-Cu LDO materials of Examples 1, 2, 3 and 4 are shown in Figure 2. Figure 1 As shown, from Figure 1 The crystal planes of Co3O4 and CuO can be seen in the Fe3O4@Co-Cu LDO, indicating that Fe3O4@Co-Cu LDO was successfully synthesized. As the amount of Cu(NO3)2·6H2O increases, the diffraction peak corresponding to CO3O4 disappears, and the diffraction peak intensity of CuO increases, indicating that the CuO species on the catalyst surface increase.

[0066] like Figure 2 As shown, it can be seen that the particle size of Fe3O4@Co-Cu LDO nanoparticles is 100-500nm.

[0067] 0.01-0.07 g of the Fe3O4@Co-Cu LDO of Example 3 was weighed and placed in a 100 mL beaker. 40 ppm of famciclovir (FCV) and 0.7 mmol / L of persulfate were then added, respectively, and stirred at room temperature. At regular intervals, 1 mL of the sample was taken from the beaker and placed in a 1.5 mL centrifuge tube pre-added with 0.3 mL of anhydrous ethanol and mixed. The mixed sample was then filtered through a 0.22 μm PTFE filter membrane to test the FCV concentration, which was used to evaluate the catalytic performance of each catalyst. The test results are shown in FIG. Figure 3 As shown, from Figure 3 It can be seen that the addition amount of Fe3O4@Co-Cu LDO affects the catalytic activity of the composite material, among which the catalyst dosage of 0.05 g / L shows the best catalytic performance.

[0068] The catalytic performance of Fe3O4@Co-Cu LDO prepared in Example 3 was evaluated. The FCV with an initial concentration of 10-60 mg / L was degraded according to the above operation. The test results are shown in the figure. Figure 4 As shown, from Figure 4 As can be seen from the figure, within the same reaction time, as the initial FCV concentration increases, the degradation efficiency decreases. At an initial concentration of 10-60 mg / L, the degradation efficiency of FCV after 40 minutes of reaction is greater than 80%, and at an initial concentration of 10-20 mg / L, the degradation efficiency reaches 100% within 30 minutes.

[0069] The cyclic performance of the Fe3O4@Co-Cu LDO prepared in Example 3 was evaluated. The suspension was subjected to magnetic recovery, washing, drying, and grinding to obtain the recycled material. The recovered Fe3O4@Co-Cu LDO was subjected to the next degradation process under the same conditions until the fifth cycle. The details of the cyclic experiment are shown in Figure 5 After 5 consecutive recovery tests, the degradation rate of FCV was higher than 80%.

[0070] The free radicals of the activated persulfate of Fe3O4@Co-Cu LDO prepared in Example 3 were detected by paramagnetic resonance spectrometer. The test results are as follows: Figure 6 As shown, DMPO-HO · and DMPO-SO · 4 - The detection of the signal confirmed the HO · and SO · 4 - The presence of triple TEMP- 1 The existence of the characteristic peak of O2 shows that 1 The production of O2. This indicates that the active species produced in this catalytic system include free radicals SO · 4 - , HO · and non-free radicals 1 O2.

[0071] The effects of Fe3O4@Co-Cu LDO activated PMS on the degradation of FCV system were evaluated. Sulfate and humic acid in actual wastewater can capture free radicals to generate new free radicals and compete with pollutants, resulting in a decrease in the degradation efficiency of pollutants, such as Figure 7 As shown in Figure 3, sulfate and humic acid had little effect on FCV degradation.

[0072] The degradation performance of Fe3O4@Co-Cu LDO activated PMS prepared in Example 3 was evaluated for different pharmaceutical pollutants. In addition to FCV, acyclovir (ACV), lamivudine (3-TC) and favipiravir (FAV) were selected as pollutants and degraded under the same conditions. The results are shown in Figure 3. Figure 8 As shown in the figure, at 25 °C, with 0.05 g / L catalyst, 0.7 mM oxidant concentration, and no pH adjustment, 40 mg / L of ACV, 3-TC, and FAV were all completely degraded within 40 min, indicating that the Fe3O4@Co-Cu LDO / PMS system has a good degradation effect on various drugs.

[0073] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a magnetic cobalt-copper-based catalyst, characterized in that: The following steps are involved: S1, mixing Fe3O4 nanoparticles and a methanol solution of 2-methylimidazole with a methanol solution of cobalt nitrate hexahydrate, collecting the precipitate with a magnet, washing and drying it, to obtain a magnetic template; S2, adding the ethanol solution of copper nitrate hexahydrate to the ethanol solution of the magnetic template, ultrasonically reacting, collecting the product with a magnet, and washing to obtain Fe3O4@Co-Cu LDH; S3. Calcinate Fe3O4@Co-Cu LDH to obtain a magnetic cobalt-copper-based catalyst.

2. The preparation method according to claim 1, wherein The preparation method of Fe3O4 particles comprises the following steps: After ferric chloride hexahydrate is dissolved in ethylene glycol, polyethylene glycol and sodium acetate are added to the solution and stirred to obtain a mixed solution, the mixed solution is subjected to a hydrothermal reaction, and after the reaction, the Fe3O4 nanoparticles are finally obtained by magnetic separation, water washing, alcohol washing, and drying.

3. The preparation method according to claim 2, wherein The concentration of ferric chloride hexahydrate in the mixed solution is 0.12-0.13 mol / L, the concentration of polyethylene glycol is 20-30 g / L, and the concentration of sodium acetate is 85-95 g / L.

4. The preparation method according to claim 2, wherein The temperature of the hydrothermal reaction is 190-210 °C and the time is 16-24 h.

5. The preparation method according to claim 1, wherein In step S1, the concentration of Fe3O4 nanoparticles in the methanol solution of Fe3O4 nanoparticles and 2-methylimidazole is 0.4-0.6 g / L, the concentration of 2-methylimidazole is 35-45 g / L, the concentration of cobalt nitrate hexahydrate in the methanol solution of cobalt nitrate hexahydrate is 40-50 g / L, the volume ratio of the methanol solution of Fe3O4 nanoparticles and 2-methylimidazole to the methanol solution of cobalt nitrate hexahydrate is 1:0.9-1.1, and the stirring time is 20-28 h.

6. The preparation method according to claim 1, wherein In step S2, the concentration of the ethanol solution of copper nitrate hexahydrate is 5-20 g / L, the concentration of the ethanol solution of the magnetic template is 1.4-1.6 g / L, the volume ratio of the ethanol solution of copper nitrate hexahydrate to the ethanol solution of the magnetic template is 0.3-0.5:1, and the ultrasonic reaction time is 30-90 min.

7. The preparation method according to claim 1, wherein In step S3, the calcination temperature is 250-350° C. and the calcination time is 2.5-3.5 h.

8. A magnetic cobalt-copper-based catalyst, characterized in that The method is obtained by the preparation method according to any one of claims 1 to 7.

9. Use of the magnetic cobalt-copper-based catalyst in treating wastewater according to claim 8, characterized in that: Catalytic degradation of organic matter in wastewater in a persulfate system.

10. Use of the magnetic cobalt-copper-based catalyst in treating wastewater according to claim 9, characterized in that: The organic matter includes drugs, and the drugs include at least one of famciclovir, acyclovir, lamivudine and favipiravir.

11. A method for treating organic matter in wastewater, characterized in that: The magnetic cobalt-copper-based catalyst and persulfate as claimed in claim 8 are added to wastewater containing organic matter to treat the wastewater.

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