Copper-cobalt oxide catalyst as well as preparation method and application thereof

Abstract

The invention discloses a copper-cobalt oxide catalyst and a preparation method and application thereof, and belongs to the technical field of sewage purification. According to the invention, CuSO4. 5H2O, CoSO4. 7H2O and urea are used as raw materials, vesuvianite gravel is used as a matrix, and water and triethylene glycol are used as solvents to prepare the copper-cobalt oxide catalyst. The copper-cobalt bimetallic catalyst can be applied to catalytic treatment of antibiotic wastewater, has a good activation effect on persulfate, is used for treatment of antibiotic wastewater represented by tetracycline, and can basically realize complete removal of tetracycline.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage purification, and in particular relates to a copper-cobalt oxide catalyst and a preparation method and application thereof. Background Art

[0002] Antibiotics are a class of drugs used to treat bacterial infections, such as cephalosporins, amoxicillin, roxithromycin, and tetracycline hydrochloride; antiviral drugs are drugs used to treat viral infections, and commonly used antiviral drugs include oseltamivir, zanamivir, nevirapine, efavirenz, etc. Antiviral / antibiotic drugs are widely used because of their good efficacy in treating viral and bacterial infections. However, improper management of drugs has led to a large number of drugs entering the ecological environment, causing serious damage and pollution to natural water bodies. In addition, the composition of antiviral / antibiotic wastewater is complex, with poor biochemical activity, making biological treatment difficult.

[0003] At present, the treatment methods for antibiotic / antiviral drug contaminated water include adsorbent adsorption, catalyst catalytic degradation and membrane separation. Among them, catalytic degradation is to use chemical methods to degrade antibiotics / antiviral drugs into non-toxic substances. This method is more thorough and does not require secondary treatment, so it is widely used.

[0004] For example, Chinese patent CN107051468A discloses a method for preparing a loaded multi-metal oxide ozone catalytic oxidation catalyst, which uses diatomite as a carrier, impregnates the carrier with a mixed solution of copper nitrate, nickel nitrate, manganese nitrate, cobalt nitrate and iron nitrate to obtain a precursor, and then dries and roasts to obtain a loaded multi-metal oxide sampling catalytic oxidation catalyst. When the catalyst is added at a dosage of 4g / L, the degradation rate of COD reaches 50-75%. Chinese patent CN115999547A discloses a method for preparing a loaded two-component metal oxide catalytic ozone oxidation catalyst and its application. It uses γ-Al2O3 pellets as catalyst carriers, loads copper and cobalt by impregnation, and finally calcines at high temperature to obtain a loaded two-component metal oxide catalytic ozone oxidation catalyst. When the catalyst is added at a dosage of 80-120mg / L, the degradation rate of ciprofloxacin, tetracycline and sulfamethoxazole is 83-95%.

[0005] Neither of these two catalysts achieved complete degradation of antibiotics, and the dosage was large, so the efficiency of the catalysts needs to be improved. Summary of the invention

[0006] In view of the above technical problems, the present invention proposes a copper-cobalt oxide catalyst and its preparation method and application. The catalyst can efficiently activate persulfate (PMS) and effectively degrade antibiotic (tetracycline hydrochloride) wastewater. Compared with traditional catalysts, the catalyst has better catalytic effect, and the generated non-free radicals and free radicals are the main active species for the degradation of antibiotics.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] The technical solution of the first aspect of the present invention is to provide a method for preparing a copper-cobalt oxide catalyst, using volcanic rock crushed stone as a matrix, loading copper salt, cobalt salt and urea by impregnation method, and then preparing a catalyst precursor by hydrothermal reaction, and then calcining after drying to obtain the copper-cobalt catalyst.

[0009] CuO in the copper-cobalt catalyst prepared by the present invention can provide oxygen vacancies in electron-rich active centers. At the same time, there is a phenomenon of mutual conversion of valence states between divalent copper and monovalent copper. The two valence states generate electrons during the mutual conversion process, and these electrons help to decompose the samples adsorbed on the catalyst surface into various active oxygen species. Cobalt oxide can obtain stronger free radical adsorption capacity through electron transfer of divalent cobalt and trivalent cobalt to promote the catalytic reaction. Urea participates in the reaction so that a certain amount of N element is doped in the catalyst and the formation of oxygen vacancies in the catalyst is promoted. Volcanic rock crushed stone serves as a carrier matrix of the catalyst, which can well load copper oxide and cobalt oxide. At the same time, volcanic rock itself has a certain adsorption effect, which helps to cooperate with the catalyst to achieve degradation reaction. In addition, the particle size of the single catalyst powder is small, and the recovery rate of the catalyst is not high. Adding cheap volcanic rock crushed stone as a carrier can better realize the recovery of the catalyst, saving economic costs to a certain extent. The bimetallic copper-cobalt oxide catalyst prepared from the above raw materials can significantly and efficiently activate PMS, thereby generating non-free radicals ( 1 O2) and free radicals (O2 - 、SO4· - , ·OH, etc.) active species, on the active sites provided by the catalyst itself, effectively achieve the degradation of tetracycline hydrochloride.

[0010] Furthermore, a method for preparing a copper-cobalt oxide catalyst comprises the following steps:

[0011] Copper salt, cobalt salt and urea (CH4N2O) were dispersed in deionized water and triethylene glycol (C6H 14 O4) in a mixed solvent to obtain a mixed solution;

[0012] adding volcanic rock crushed stones to the mixed solution and stirring to obtain a supported catalyst;

[0013] The supported catalyst is subjected to a hydrothermal reaction, cooled to room temperature, centrifuged, filtered, dried, and calcined to obtain a copper-cobalt oxide catalyst.

[0014] Copper salts and cobalt salts are required to have high solubility in water. Optionally, the copper salt includes but is not limited to CuSO4, CuCl2 or Cu(NO3)2; the cobalt salt includes but is not limited to CoSO4, CoCl2 or Co(NO3)2.

[0015] Furthermore, the mass ratio of the copper salt, the cobalt salt and the urea is 1:2:1.

[0016] Furthermore, the volume ratio of the deionized water to triethylene glycol is 1:3.

[0017] Furthermore, the stirring process is specifically: stirring for 12 hours at a rotation speed of 300 rpm.

[0018] Furthermore, the hydrothermal reaction process is specifically: reacting at a temperature of 180° C. for 6 hours.

[0019] Furthermore, the drying process is specifically as follows: storing in a vacuum drying oven at 90° C. for 6 hours.

[0020] Furthermore, the calcination process is specifically as follows: in a tubular furnace, the temperature is raised to 500° C. at a heating rate of 2° C. / min, and then kept at this temperature for 2 hours.

[0021] The technical solution of the second aspect of the present invention is to provide a copper-cobalt oxide catalyst prepared by the above-mentioned preparation method.

[0022] The technical solution of the third aspect of the present invention is to provide an application of a copper-cobalt oxide catalyst in treating wastewater containing antibiotics.

[0023] Furthermore, the antibiotic is tetracycline hydrochloride.

[0024] The technical solution of the fourth aspect of the present invention is to provide an advanced oxidation system for degrading tetracycline hydrochloride, using a copper-cobalt oxide catalyst as an activator for activating persulfate.

[0025] In the present invention, copper salt and cobalt salt are used to synthesize transition metal oxides of the catalyst, urea is used to dope N element and promote the formation of vacancies in the catalyst during the synthesis of the catalyst, volcanic rock crushed stone is used as a carrier matrix of the catalyst, and water and triethylene glycol are used as solvents for dissolving the above chemical reagents. The bimetallic copper-cobalt oxide catalyst prepared from the above raw materials can significantly and efficiently activate PMS, thereby generating non-free radicals ( 1 O2) and free radicals (O2 - 、SO4· -, ·OH, etc.) active species, on the active sites provided by the catalyst itself, effectively achieve the degradation of tetracycline hydrochloride.

[0026] Compared with the prior art, the present invention has the following advantages and technical effects:

[0027] The present invention relies on advanced oxidation technology to degrade antibiotic drug wastewater. A heterogeneous catalyst is used to activate PMS to generate active oxides, which effectively degrades organic wastewater. The present invention selects catalysts with simple preparation conditions, easy-to-obtain materials, good catalytic effects, and green, environmentally friendly, simple to operate, and efficient removal of antibiotic drugs through the preparation of catalysts and the optimization of multi-means synergistic catalytic oxidation systems, thereby obtaining a method for treating antiviral / antibiotic drug wastewater with high catalytic efficiency and strong use value.

[0028] The copper-cobalt oxide catalyst prepared by the invention can effectively activate PMS to generate free radicals and non-free radicals, thereby efficiently degrading antibiotic wastewater containing tetracycline hydrochloride, and the process is relatively green and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings constituting 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 an improper limitation of the present invention. In the accompanying drawings:

[0030] Figure 1 The catalyst prepared in Example 1 and Comparative Examples 1-4 degrades tetracycline hydrochloride. t / C0 efficiency curve, where the horizontal axis represents time, unit min, and the vertical axis represents C t / C0, unit %, the experiment was carried out at room temperature;

[0031] Figure 2 The degradation rate constant curve of tetracycline hydrochloride degradation by the catalyst prepared in Example 1 and Comparative Examples 1-4, wherein the abscissa represents the mass ratio of CuSO4·5H2O and CoSO4·7H2O, and the ordinate represents k, in units of min -1 , the experiments were carried out at room temperature. DETAILED DESCRIPTION

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0034] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0035] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0036] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0037] The present invention provides a method for preparing a copper-cobalt oxide catalyst, comprising the following steps:

[0038] Cobalt salt, copper salt and urea (CH4N2O) were added to deionized water and triethylene glycol (C6H 14 O4) in a mixed solvent, so that copper sulfate, cobalt sulfate and urea are evenly dispersed in the mixed solvent to obtain a mixed solution;

[0039] Add volcanic rock crushed into a length, width and height of about 1-3 mm into the mixed solution and stir together, so that the mixed solution can grow well on the volcanic rock crushed stone to obtain a supported catalyst;

[0040] The supported catalyst is subjected to a hydrothermal reaction, and after the reaction is completed, the solution is cooled to room temperature, and then the solution obtained by the hydrothermal synthesis is centrifuged and filtered to obtain a solid catalyst precursor, and then the catalyst precursor is dried and calcined to obtain a copper-cobalt oxide catalyst.

[0041] In some embodiments, volcanic rock needs to be pretreated before use, and the specific pretreatment steps are: put the volcanic rock into a sealed bag, wrap the outer layer with foam plastic as a buffer, use a hammer to smash the volcanic rock into broken particles of different particle sizes, and select the particles with a length, width and height within the range of 1-3 mm after screening, remove impurities on the surface of the substrate by ultrasonication in deionized water for 3 hours, then rinse the substrate 3 times with anhydrous ethanol, and put it in an oven to dry.

[0042] The copper salt and the cobalt salt only need to have high solubility in water, that is, the copper salt and the cobalt salt are soluble copper salts and cobalt salts. Optionally, the copper salt includes but is not limited to CuSO4, CuCl2 or Cu(NO3)2; the cobalt salt includes but is not limited to CoSO4, CoCl2 or Co(NO3)2. When used as raw materials, hydrates of copper salts and cobalt salts are selected. As a typical but non-limiting example, the copper salt in the embodiment is CuSO4·5H2O, and the cobalt salt is CoSO4·7H2O.

[0043] In a preferred embodiment of the present invention, the mass ratio of CuSO4.5H2O, CoSO4.7H2O and urea is 1:2:1.

[0044] In a preferred embodiment of the present invention, the volume ratio of deionized water to triethylene glycol is 1:3.

[0045] In a preferred embodiment of the present invention, the stirring process is specifically: stirring for 12 hours at a rotation speed of 300 rpm.

[0046] In a preferred embodiment of the present invention, the hydrothermal reaction process is as follows: the supported catalyst is placed in a high-pressure reactor and reacted in a vacuum drying oven at 180° C. for 6 hours.

[0047] In a preferred embodiment of the present invention, the drying process is specifically: storing in a vacuum drying oven at 90° C. for 6 hours.

[0048] In a preferred embodiment of the present invention, the calcination process is specifically as follows: in a tubular furnace, the temperature is increased to 500° C. at a heating rate of 2° C. / min, and then kept at this temperature for 2 hours.

[0049] The embodiment of the present invention also provides a copper-cobalt oxide catalyst that can be prepared using the above preparation method.

[0050] The embodiment of the present invention also provides the use of the copper-cobalt oxide catalyst in treating wastewater containing tetracycline hydrochloride.

[0051] The copper-cobalt oxide catalyst prepared by the present invention can significantly and efficiently activate PMS to generate non-free radicals ( 1O2) and free radicals (O2 - 、SO4· - , ·OH, etc.) active species, on the active sites provided by the catalyst itself, effectively achieve the degradation of tetracycline hydrochloride.

[0052] The "room temperature" mentioned in the present invention refers to 25±2°C unless otherwise specified.

[0053] The raw materials used in the present invention are all purchased from the market.

[0054] The technical solution of the present invention is further illustrated by the following embodiments.

[0055] Example 1

[0056] A method for preparing a copper-cobalt oxide catalyst comprises the following steps:

[0057] (1) Substrate pretreatment: two pieces of volcanic rocks were placed in a sealed bag, and the outer layer was wrapped with foam plastic as a buffer. The volcanic rocks were crushed into particles of different sizes using a hammer. After screening, particles with a length, width and height of 1-3 mm were selected. Impurities on the surface of the substrate were removed by ultrasonic treatment in deionized water for 3 h. The substrate was then rinsed with anhydrous ethanol for 3 times and placed in an oven for drying.

[0058] (2) Weigh 0.4 g of CuSO4·5H2O, 0.8 g of CoSO4·7H2O and 0.4 g of urea and add 10 mL of deionized water and 30 mL of triethylene glycol (C6H 14 O4) in a mixed solvent, stirring on a magnetic stirrer until the solution is gray-pink, mixed evenly, and no undissolved drugs are present, to obtain a mixed solution (the mass ratio of CuSO4·5H2O to CoSO4·7H2O is 1:2);

[0059] (3) Weighing 2 g of the substrate prepared in step (1) and placing it into the mixed solution prepared in step (2), stirring the mixture at a speed of 300 rpm for 12 h to obtain a supported catalyst;

[0060] (4) The supported catalyst was transferred into a 100 mL polytetrafluoroethylene-lined reactor, which was sealed and placed in an oven for hydrothermal reaction at 180° C. for 6 hours. After the reaction was completed, the product was cooled to room temperature under natural conditions, and the product was collected and centrifuged and washed three times with deionized water and anhydrous ethanol (10,000 rpm, 5 min). The washed product was placed in a vacuum drying oven at 90° C. for 6 hours. Finally, the mixed powder was loaded into a quartz boat, which was placed in the center of a tube furnace. The tube furnace was heated to 500° C. at a heating rate of 2° C. / min in an air atmosphere and calcined at this temperature for 2 hours to obtain a copper cobalt oxide catalyst, named CCO.

[0061] Comparative Example 1

[0062] The same as Example 1, except that in step (2), the mass ratio of CuSO4·5H2O to CoSO4·7H2O is 1:1, i.e., 0.4 g of CuSO4·5H2O and 0.4 g of CoSO4·7H2O.

[0063] Comparative Example 2

[0064] The same as Example 1, except that in step (2), the mass ratio of CuSO4·5H2O to CoSO4·7H2O is 1:3, i.e. 0.4 g of CuSO4·5H2O and 1.2 g of CoSO4·7H2O.

[0065] Comparative Example 3

[0066] The same as Example 1, except that in step (2), the mass ratio of CuSO4·5H2O to CoSO4·7H2O is 2:1, i.e., 0.8 g of CuSO4·5H2O and 0.4 g of CoSO4·7H2O.

[0067] Comparative Example 4

[0068] The same as Example 1, except that in step (2), the mass ratio of CuSO4·5H2O to CoSO4·7H2O is 3:1, i.e., 1.2 g of CuSO4·5H2O and 0.4 g of CoSO4·7H2O.

[0069] Application Example 1

[0070] The performance test of the copper-cobalt oxide catalyst prepared in Example 1 and Comparative Examples 1-6 for treating tetracycline hydrochloride wastewater was conducted. The specific method was as follows: a direct degradation experiment was used for testing. The degradation reaction of tetracycline hydrochloride was conducted in a 100 mL beaker containing 50 mL of tetracycline hydrochloride (TC) solution, wherein the concentration of tetracycline hydrochloride was 20 mg / L, the concentration of PMS was 0.5 mM, and the amount of catalyst added was 0.01 g / L. The reaction was conducted for 20 min, and sampling was conducted every 5 min during the reaction. After sampling, the water sample was immediately filtered with a filter membrane having a pore size of 0.22 μm, and tested with an ultraviolet-visible spectrophotometer at a wavelength of 357 nm to obtain the corresponding absorbance value, which was measured by the TC solution standard curve (y=0.0492x-0.00233 (R 2 =0.999)) and removal rate formula (η=C t / C0) to obtain the residual concentration and degradation efficiency of TC. The results are as follows Figure 1 shown.

[0071] Depend on Figure 1It can be seen that Example 1 has a good ability to degrade tetracycline hydrochloride when the dosage is only 10 mg / L. The copper-cobalt oxide catalyst prepared in Example 1 has the best degradation efficiency for tetracycline hydrochloride, and the degradation rate of tetracycline hydrochloride reaches 100% within 20 minutes, achieving complete removal of tetracycline hydrochloride. It can be seen from the data of Comparative Examples 1 and 2 that increasing the doping content of metallic cobalt improves the overall degradation efficiency, so that the degradation rate of tetracycline hydrochloride is increased from 92.4% (Comparative Example 1) to 100%, but both Comparative Example 2 and Example 1 can achieve complete degradation, but more cobalt is added, which increases the risk of cobalt metal ion leaching; it can be seen from Comparative Examples 3 and 4 that changing the amount of metallic copper added to the catalyst has almost no effect on the overall degradation efficiency, but if Figure 2 It can be seen that the degradation rate constant of Comparative Example 3 is 0.188, while the degradation rate constant of Example 1 is 0.573, which is about 3 times that of Comparative Example 3; in addition, the overall degradation effect of Comparative Example 4 is similar to that of Example 1, but the amount of metal salt added is greater, resulting in a waste of resources.

[0072] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for preparing a copper-cobalt oxide catalyst, characterized in that: The volcanic rock crushed stone is used as a matrix, copper salt, cobalt salt and urea are loaded by an impregnation method, and then a catalyst precursor is prepared by a hydrothermal reaction, and the copper-cobalt catalyst is obtained by calcining after drying.

2. The method for preparing the copper-cobalt oxide catalyst according to claim 1, characterized in that: The following steps are involved: Dispersing copper salt, cobalt salt and urea in a mixed solvent of deionized water and triethylene glycol to obtain a mixed solution; Adding a volcanic rock crushed stone matrix into the mixed solution and stirring to obtain a supported catalyst; The supported catalyst is subjected to a hydrothermal reaction, cooled to room temperature, centrifuged, filtered, dried, and calcined to obtain a copper-cobalt oxide catalyst.

3. The method for preparing the copper-cobalt oxide catalyst according to claim 1, characterized in that: The copper salt is selected from CuSO4, CuCl2 or Cu(NO3)2; and / or The cobalt salt is CoSO4, CoCl2 or Co(NO3)2.

4. The method for preparing the copper-cobalt oxide catalyst according to claim 2, characterized in that: The mass ratio of the copper salt, the cobalt salt and the urea is 1:2:

1.

5. The method for preparing the copper-cobalt oxide catalyst according to claim 2, characterized in that: The hydrothermal reaction process is specifically: reacting at a temperature of 180° C. for 6 hours.

6. The method for preparing the copper-cobalt oxide catalyst according to claim 2, characterized in that: The drying process is specifically as follows: Store in a vacuum oven at 90°C for 6 hours; and / or The calcination process is specifically as follows: in a tubular furnace, the temperature is raised to 500° C. at a heating rate of 2° C. / min, and then kept at this temperature for 2 hours.

7. A copper-cobalt oxide catalyst, characterized in that: The method is prepared by any one of claims 1 to 6.

8. Use of the copper-cobalt oxide catalyst as claimed in claim 7 in treating wastewater containing antibiotics.

9. The use according to claim 8, characterized in that: The antibiotic is tetracycline hydrochloride.

10. An advanced oxidation system for degrading tetracycline hydrochloride, characterized in that: The copper-cobalt oxide catalyst according to claim 7 is used as an activator for activating persulfate.

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