CuCe composite metal oxide rapidly prepared based on Joule heat as well as preparation method and application of CuCe composite metal oxide

Abstract

The invention relates to a preparation method for rapidly preparing a CuCe composite metal oxide based on Joule heat and application of the CuCe composite metal oxide. The method comprises the following steps: uniformly mixing and stirring Cu salt and Ce salt, evaporating the solution to dryness, and then instantly heating by Joule heat to construct the CuCe composite metal oxide catalyst with high-concentration asymmetric oxygen vacancies in situ. The instantaneous heating method can effectively avoid agglomeration of CuOX or CeOX prepared by a traditional scheme, in addition, the concentration of active substances can be adjusted by adjusting the reaction voltage, the electric shock time, the reaction atmosphere and the like of Joule heat, and finally the reaction activity is improved. The time required by a traditional calcining method can be shortened to several microseconds to several seconds from several hours, so that the time and the energy cost are greatly reduced, and the defects of insufficient active substances generated by a traditional hydrothermal method, a coprecipitation method or calcining or sintering are overcome.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of environmental functional materials, and particularly relates to a preparation method of CuCe composite metal oxide asymmetric oxygen vacancies based on Joule heat and application thereof. BACKGROUND

[0002] In recent years, water body antibiotic pollution has become a global environmental health crisis. High-stability antibiotics (such as tetracyclines and sulfonamides) are difficult to be effectively degraded by traditional water treatment processes, leading to the spread of drug-resistant genes and ecological toxicological effects. Although advanced oxidation technologies (such as photocatalysis and ozone oxidation) have certain potential, they generally face problems such as low catalyst efficiency, high cost and secondary pollution. Therefore, it is crucial to develop a new type of catalyst that can efficiently activate persulfate (such as PMS) to generate free radicals and achieve rapid mineralization of antibiotics.

[0003] Transition metal oxides, especially Cu / Ce composite systems, have great potential in activating PMS to degrade antibiotics due to their unique electronic structures (such as Ce 3+ / Ce 4+ , Cu δ+ valence state adjustable, oxygen storage capacity brought by redox potential, and strong metal-support interaction (SMSI effect). However, traditional preparation methods (such as solid-phase mixing, hydrothermal method, coprecipitation, and high-temperature calcination) have disadvantages such as high energy consumption, long time consumption, and complex process, and most importantly, they are difficult to precisely control oxygen vacancies, especially to achieve differential construction of CuCe asymmetric oxygen vacancies. Studies have shown that CuCe asymmetric oxygen vacancies are the active sites for most reactions, which can effectively improve the transmission and transport of electrons. Obviously, the current traditional method of preparing CuCe asymmetric oxygen vacancies restricts the electron transfer efficiency and performance improvement of the catalyst.

[0004] Joule heat technology can achieve instantaneous ultra-high temperature (up to 1500℃) and ultra-fast cooling (>10 4 ℃ / s) within milliseconds (ms) to seconds (s) through the material's own resistance, bringing revolutionary advantages to catalyst preparation: significantly improving energy and time efficiency (energy consumption can be reduced by 1-2 orders of magnitude), precisely controlling microstructure (producing high-concentration defects such as oxygen vacancies and maintaining high specific surface area), and achieving controllable construction of oxygen vacancy concentration and distribution. Although this technology has been applied to single metal oxides (such as CuO and CeO2), it is still a blank to use it in CuCe bimetallic composite systems and construct key "asymmetric oxygen vacancies". In view of the advantages of Cu / Ce oxides, asymmetric oxygen vacancies, and Joule heat, the application couples the above advantages and uses Joule heat method to prepare CuCe composite oxide asymmetric oxygen vacancies asymmetric oxygen vacancies catalyst and apply it to efficient degradation of water body antibiotics. SUMMARY

[0005] The purpose of this invention is to overcome the problems of high cost, long preparation time, and complex preparation steps of existing traditional catalysts, and to provide a novel method for the rapid and large-scale preparation of CuCe composite metal oxides. The prepared CuCe composite oxide catalyst with high concentration of asymmetric oxygen vacancies has good catalytic degradation performance on tetracycline hydrochloride wastewater in water.

[0006] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution:

[0007] This invention synthesizes a CuCe composite metal oxide catalyst with a high concentration of asymmetric oxygen vacancies by adjusting the ratio of copper and cerium salts and changing parameters such as electrostatic discharge voltage, reaction atmosphere, and electrostatic discharge time. The specific technical solution is as follows:

[0008] A method for rapidly preparing asymmetric oxygen vacancies in CuCe composite metal oxides based on Joule heating and its application includes the following steps: Cerium salt and copper salt are dissolved in a mixed solution of distilled water and organic solvent, respectively, to obtain cerium salt solution A and copper salt solution B; then solution B is slowly added dropwise to solution A and continuously mixed and stirred until homogeneous, and then transferred to an oven to evaporate the mixed solvent to obtain copper-cerium mixed powder; finally, the copper-cerium mixed powder is subjected to several pulsed discharges in a self-made Joule heating device under air conditions to finally obtain CuCe composite metal oxides.

[0009] The specific method is as follows:

[0010] (1) Preparation of CuCe mixed salt powder: Weigh copper salt and cerium salt (molar mass ratio of copper salt and cerium salt is 1:0, 1:0.1, 1:0.3, 1:0.5, 1:0.7, 1:0.9, 0:1, total molar mass is 10 mmol) and place them in a mixture of distilled water and organic solvent and stir until completely dissolved to form solution A and solution B. Then, slowly add solution B to solution A to form mixed solution C. Stir mixed solution C at room temperature, then transfer it to an oven to dry in order to remove the mixed solution. After drying, cool it to room temperature to finally obtain CuCe composite salt powder for use. The concentration of copper salt in solution A is 0-200 mmol / L. The concentration of cerium salt in solution B is 0-200 mmol / L. In this invention, the concentration of copper salt in solution A and the concentration of cerium salt in solution B are not 0.

[0011] (2) Activation of activated carbon fiber: Cut activated carbon fiber and place it in a Joule heating device, then evacuate the vacuum, and then adjust the voltage and firing time to activate the activated carbon fiber.

[0012] (3) Preparation of CuCe composite metal oxide: The CuCe mixed salt powder obtained in step (1) is weighed and placed in the activated carbon fiber obtained in step (2), and then dried by bombarding under a certain voltage. After drying, the atmosphere is switched to air. Then, the voltage and other parameters are adjusted for transient heating, and finally the CuCe composite metal oxide is obtained.

[0013] In the above method, in step (1), the copper salt is copper sulfate; the cerium salt is cerium acetate; the organic solvent is anhydrous ethanol, and the total volume of distilled water and anhydrous ethanol is 50-100 mL; the volume ratio of distilled water to anhydrous ethanol is 1:1.

[0014] In the above method, in step (2), the preparation method of the activated carbon fiber is as follows: the length and width of the activated carbon fiber are 8.0-10 cm x 5.0-6.0 cm, respectively, and then the activated carbon fiber is placed in a joule heat device and then vacuumized. The joule heat device is as shown in Figure 3 The voltage is adjusted to 90-120 V, the shock time is 0.3-0.7 s, and the shock activation frequency is 5-8 times.

[0015] In the above method, in step (3), the mass of the CuCe mixed salt powder of step (1) is 0.3-0.5 g; the drying condition voltage is 50-80 V, the shock time is 0.3-0.7 s, and the shock frequency is 5-8 times.

[0016] In the above method, in step (3), the preparation condition voltage is 100-120 V, the shock time is 0.3-0.7 s, and the shock frequency is 5-8 times.

[0017] A CuCe composite metal oxide, characterized in that the CuCe composite metal oxide is still mainly in the form of pure phase CeO2, and no diffraction peak of CuOx is observed. The metal oxide has a high concentration of asymmetric oxygen vacancies, and is used for degradation of antibiotic tetracycline hydrochloride. More than 80% of tetracycline can be degraded in 20 min.

[0018] The CuCe composite metal oxide is used for degradation of antibiotic tetracycline in water by persulfate.

[0019] Compared with the traditional conventional synthesis method, the CuCe composite metal oxide prepared by the preparation method has more uniform size and morphology, and the active sites are more uniformly distributed, thereby showing more excellent ability of catalytic oxidation of VOCs and good stability. Compared with the CuCe composite metal oxide prepared by the traditional method, the preparation process of the CuCe composite metal oxide catalyst is simple and easy to operate, does not need to additionally add a hydrothermal reaction, water washing, and the reaction is rapid, and the scale-up preparation can be realized in a very short time, and the CuCe composite metal oxide catalyst has wide application prospect and high efficient catalytic activity.

[0020] In the above method, in step (1), the copper salt is copper sulfate, and the cerium salt is cerium acetate; the molar mass ratio of the copper salt and the cerium salt with a certain molar mass is 1:0, 1:1, 1:3, 1:5, 1:7, 1:9, 0:1, and the total molar mass is 10 mmol; the organic solvent is anhydrous ethanol, and the total volume of the distilled water and the anhydrous ethanol is 50 mL; the volume ratio of the distilled water and the anhydrous ethanol is 1:1.

[0021] In the above method, in step (2), the length and width of the activated carbon fiber are 8.0 cm*5.5 cm respectively; the joule heat device is self-made; the activation voltage is 50-80 V, the electric shock time is 0.3-0.7 s, and the electric shock frequency is 5-8 times.

[0022] In the above method, in step (3), the mass of the mixed salt powder is 0.3-0.5 g; the preparation condition voltage is 100-120 V, the electric shock time is 0.3-0.7 s, and the electric shock frequency is 5-8 times.

[0023] The prepared CuCe composite metal oxide catalyst in the application has the characteristics of uniform morphology and size, and the CuCe active sites are uniformly dispersed; the catalyst can expose more active sites, has strong redox performance, shows more excellent ability of catalytic degradation of antibiotics in water, and has good stability and circulation.

[0024] Compared with the prior art, the application has the following advantages:

[0025] 1. The traditional methods such as hydrothermal method and coprecipitation method often need to add a large amount of precipitant or complexing agent to precipitate copper and cerium into corresponding hydroxides, which often causes the precipitant or complexing agent to be difficult to clean in the later period, in addition, the added metal salt cannot be completely generated due to the influence of the preparation condition, thereby causing waste. However, the preparation method does not need to additionally add a precipitant or complexing agent, and only needs to dry the metal salt to completely precipitate the added metal salt, and then the CuCe composite metal oxide can be prepared by using joule heat pulse, thereby realizing the full utilization of the added metal salt.

[0026] 2. The traditional preparation of metal oxides often needs to be calcined in air conditions, and the traditional calcination method often causes agglomeration or sintering, or uneven heating, etc., thereby leading to the problem of uneven catalytic activity of the catalyst. The preparation method can quickly realize the preparation of metal oxide catalysts. The agglomeration and sintering of metal oxides can be effectively inhibited, the corresponding reactive components are more uniform, and more active sites can be exposed, thereby improving the activity of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 XRD spectrum of CuCe oxide prepared by the application.

[0028] Figure 2 Activity diagram of tetracycline degradation of CuCe composite metal oxide prepared by the application;

[0029] Figure 3 Structure diagram of the joule heat device. DETAILED DESCRIPTION

[0030] The application will be further specifically and in detail described below in combination with specific embodiments, but the embodiments of the application are not limited thereto. For process parameters not specifically indicated, conventional techniques can be referred to.

[0031] In the following examples, the joule heat device includes a quartz glass tube, a graphite electrode 2, a pure copper electrode 3, an in-situ reaction cell 4, a vacuum pump 5, a power supply 6 and a controller 7. The quartz glass tube is internally provided with the pure copper electrode 3, the pure copper electrode 3 is internally connected with the graphite electrode 2, and the graphite electrode 2 is placed with the sample 1. The pure copper electrode 3 is connected with the power supply 6, and the controller 7 is connected in series in the circuit between the power supply 6 and the pure copper electrode 3. The quartz glass tube is placed in the in-situ reaction cell 4, and the in-situ reaction cell 4 is connected with the vacuum pump 5. The controller 7 is used to control the voltage, the shock time and the shock times.

[0032] Example 1

[0033] (1) 10 mmol of cerium acetate was dissolved in 50 mL of a mixed solvent of distilled water and anhydrous ethanol; then it was stirred at room temperature for 30 min. Then it was placed in an 80℃ oven to dry to obtain a powder for standby.

[0034] (2) The 8.8 cm x 5.0 cm activated carbon fiber was cut and placed in the joule heat device for graphitization. Specifically, the activated carbon fiber was shocked 5 times under vacuum at a voltage of 120V, and each shock time was 0.7s for standby.

[0035] (3) Take 0.3 g of the standby sample in (1) above and place it in the graphitized activated carbon fiber in (2), then dry it at 50 V to remove residual water vapor, then adjust the voltage to 120 V, and give it 5 electric shocks of 0.3 s each, and finally vacuumize it and cool it rapidly, then inject air into the Joule heat reaction pool. Take out the sample, and finally obtain a pure-phase CeO2 sample standby.

[0036] Example 2

[0037] Take 10 mmol of cerium acetate and dissolve it in 50 mL of a mixed solvent of distilled water and anhydrous ethanol to obtain solution A; then take 1, 3, 5, 7, and 9 mmol of copper acetate respectively and dissolve them in 50 mL of a mixed solvent of distilled water and anhydrous ethanol to obtain solution B, then slowly add the B solution to the A solution to obtain mixed solution C, and stir it at room temperature for 30 min. Then place it in an 80℃ oven to dry to obtain a powder standby. The subsequent steps are consistent with steps (2) and (3) in Example 1, and finally obtain a series of composite metal oxides with different Cu:Ce ratios standby, and the XRD of the corresponding Cu:Ce composite metal oxides is shown in Figure 1 , and it can be seen from Figure 1 that the corresponding diffraction peaks are all pure-phase CeO2, and as the Cu content increases, some CuO diffraction peaks also appear, but CeO2 crystal phase is still dominant.

[0038] Example 3

[0039] Take 60 mg of the metal oxide in the above example and place it in 100 mL of a tetracycline hydrochloride aqueous solution containing 20 mg / L. Then add 60 mg of potassium peroxymonosulfate and continuously stir at 600 r / min, and continuously monitor the corresponding absorbance during the stirring process, and finally obtain the corresponding activity graph of degrading tetracycline hydrochloride, as shown in Figure 2 , the introduction of Cu can significantly increase the activity of Cu:Ce composite metal oxides in degrading tetracycline, and the higher the Cu content, the higher the corresponding degradation activity when Ce:Cu is 1:0.7, which can achieve about 85% degradation of tetracycline in 10 min.

[0040] The above examples are only used to illustrate the technical solutions of the present application and are not strictly limited by the conditions. Those of ordinary skill in the art should understand that various changes can be made to the details or forms without departing from the spirit and scope of the present application as defined in the claims.

Claims

1. A method for rapid preparation of CuCe composite metal oxide based on Joule heating, characterized by, It comprises the following steps: (1) Preparation of CuCe mixed salt powder: weigh copper salt and cerium salt respectively into a distilled water and organic solvent mixed solution, fully stir and dissolve to form solution A and solution B, then add solution B to solution A to form mixed solution C; stir the mixed solution C at room temperature, then transfer it to an oven for drying to remove the mixed solution, cool to room temperature after drying, and finally obtain CuCe composite salt powder for standby; the concentration of copper salt in solution A is 0-200 mmol / L; the concentration of cerium salt in solution B is 0-200 mmol / L; (2) Activation of activated carbon fiber: cut the activated carbon fiber into a joule heat device, then vacuumize, then adjust the voltage and click time, and activate the activated carbon fiber; (3) Preparation of CuCe composite metal oxide: weigh the CuCe mixed salt powder obtained in step (1) into the activated carbon fiber obtained in step (2), and perform voltage bombardment drying in a joule heat device; after drying, switch the atmosphere to air; then adjust the voltage parameters for instantaneous heating to obtain CuCe composite metal oxide.

2. The method for rapidly preparing CuCe composite metal oxides based on Joule heat according to claim 1, characterized in that, In step (1), the copper salt is copper sulfate; the cerium salt is cerium acetate; the organic solvent is anhydrous ethanol, and the total volume of the distilled water and anhydrous ethanol is 50-100 mL; the volume ratio of the distilled water to anhydrous ethanol is 1:

1.

3. The method for rapid preparation of CuCe composite metal oxide based on Joule heat according to claim 1, characterized in that, In step (1), the molar mass ratio of copper salt to cerium salt is 1:0.1, 1:0.3, 1:0.5, 1:0.7, or 1:0.9, and the total molar mass is 10 mmol.

4. The method for rapidly preparing CuCe composite metal oxide based on Joule heat according to claim 1, characterized in that, In step (2), the preparation method of the activated carbon fiber activation is as follows: the length and width of the activated carbon fiber are 8.0-10 cm x 5.0-6.0 cm, which is placed in a joule heat device, then vacuumized; the voltage is adjusted to 90-120 V, and the electric shock time is 0.3-0.7 s; the electric shock activation frequency is 5-8 times.

5. The method for fast preparation of CuCe composite metal oxide based on Joule heat according to claim 1, characterized in that, In step (3), the mass of the CuCe mixed salt powder weighed in step (1) is 0.3-0.5 g; the drying condition voltage is 50-80 V, the electric shock time is 0.3-0.7 s; and the electric shock frequency is 5-8 times.

6. The method for fast preparation of CuCe composite metal oxide based on Joule heat according to claim 1, characterized in that, In step (3), the preparation condition voltage is 100-120 V, the electric shock time is 0.3-0.7 s; and the electric shock frequency is 5-8 times.

7. The method for fast preparation of CuCe composite metal oxide based on Joule heat according to claim 1, characterized in that, The joule heat device comprises a quartz glass tube, a graphite electrode (2), a pure copper electrode (3), an in-situ reaction tank (4), a vacuum pump (5), a power supply (6), and a controller (7); the pure copper electrode (3) is arranged at both ends inside the quartz glass tube, the pure copper electrode (3) is connected with the graphite electrode (2) inside, and the sample (1) is placed between the graphite electrodes (2); the pure copper electrode (3) is connected with the power supply (6), and the controller (7) is connected in series on the line between the power supply (6) and the pure copper electrode (3); the quartz glass tube is placed in the in-situ reaction tank (4), and the in-situ reaction tank (4) is connected with the vacuum pump (5); the controller (7) is used to control the voltage, electric shock time, and electric shock frequency.

8. CuCe composite metal oxide prepared by the production process according to any one of claims 1 to 7, characterized in that CuCe composite metal oxide is still dominated by pure phase CeO2, with high concentration of asymmetric oxygen vacancies.

9. Use of the CuCe composite metal oxide according to claim 8, characterized in that The CuCe composite metal oxide is used for the degradation of antibiotic tetracycline in water by persulfate.

10. Use according to claim 9, characterized in that, More than 80% of tetracycline is degraded in 20 min.

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