FeCu-coated N-C Fenton-like catalyst as well as preparation method and application thereof

Abstract

The invention discloses a FeCu-coated N-C Fenton-like catalyst and a preparation method and application thereof, and belongs to the technical field of catalysts.The preparation method of the catalyst comprises the following steps that water-soluble ferric salt, water-soluble copper salt, a carbon source and urea are dissolved in water, and a mixed solution is obtained; removing moisture in the mixed solution to obtain a solid; grinding and uniformly mixing the solid and carbonate of zinc to obtain mixed powder; and calcining the mixed powder in a protective atmosphere to obtain the FeCu-coated N-C Fenton catalyst. The adopted raw materials are cheap and easy to obtain, the operation method is simple, synthesis is convenient, the prepared FeCu-coated N-C Fenton-like catalyst can be applied to heterogeneous Fenton-like oxidation reaction, and organic pollutants are efficiently degraded. As the catalyst is simple to prepare and easy for industrial production, the degradation efficiency of pollutants is high, and the catalyst has extremely high application value in organic pollutant wastewater treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts, and particularly relates to an FeCu@N-C type Fenton catalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Water pollution poses a huge threat to human health and the water ecosystem. Among them, organic pollutants undergo biological oxidation and decomposition in water, consuming a large amount of dissolved oxygen. Once the oxygen supply in the water body is insufficient, the oxidation process will stop, causing anaerobic fermentation of organic matter, emitting a foul smell, polluting the environment, and poisoning aquatic organisms. Therefore, the development and implementation of wastewater treatment technologies are crucial for eliminating pollutants.

[0003] Currently, advanced oxidation processes (AOPs) that activate hydrogen peroxide have received continuous attention due to their high oxidation efficiency and simple operation. This process requires external energy input to cleave the peroxide bond. Several physical methods such as ultraviolet irradiation, heating, and ultrasonic waves have been proven to effectively activate hydrogen peroxide, but this greatly increases the operating cost. Due to the ease of operation and versatility of heterogeneous catalysts for activating hydrogen peroxide, it has attracted much attention. Hydrogen peroxide can be activated to generate various reactive oxygen species, such as hydroxyl radicals, superoxide radicals, and singlet oxygen, to degrade pollutants through radical and non-radical pathways. Currently, some catalysts have been used to activate hydrogen peroxide to degrade organic pollutant wastewater. However, they generally have disadvantages such as poor stability, high cost, and easy poisoning, which seriously hinder their large-scale industrial application. Therefore, the development of efficient and durable heterogeneous hydrogen peroxide catalysts is an urgent task. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an FeCu@N-C type Fenton catalyst, a preparation method thereof, and an application thereof. In the present invention, Fe and Cu are confined in an N-doped porous carbon material, and the strong binding between carbon and FeCu can change their electronic structure, which is beneficial to adsorption and reduction of the binding energy barrier, thereby significantly improving the catalytic performance.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: The present invention provides a preparation method of an FeCu@N-C type Fenton catalyst, comprising the following steps: (1) Dissolve a water-soluble iron salt, a water-soluble copper salt, a carbon source, and urea in water to obtain a mixed solution; preferably, the water-soluble iron salt is iron nitrate or iron chloride; the water-soluble copper salt is copper nitrate or copper chloride; the carbon source is glucose. Further preferably, the molar ratio of iron in the water-soluble iron salt to copper in the water-soluble copper salt is (0.5 - 2):1.

[0006] (2) Remove the moisture from the mixed solution to obtain a solid; the specific method is: place the mixed solution in an oven at 50-90 °C and heat it until the moisture is completely evaporated; (3) Grind and mix the solid with a zinc carbonate evenly to obtain a mixed powder; preferably, the zinc carbonate is zinc basic carbonate or zinc carbonate; the molar ratio of the addition amount of the zinc carbonate to the total amount of the water-soluble iron salt and the water-soluble copper salt is (5-10):(1-3).

[0007] (4) Calcinate the mixed powder in a protective atmosphere. During the calcination process, the iron salt and the copper salt are respectively transformed into iron-copper nanoparticles, which serve as catalytic active sites; glucose is dehydrated and carbonized at high temperature to form an amorphous carbon or a partially graphitized carbon skeleton; urea introduces nitrogen-doped sites to adjust the electronic structure of the carbon material and enhance the catalytic activity, and finally an FeCu@N-C Fenton-like catalyst is obtained. Preferably, the protective atmosphere is an inert gas atmosphere such as argon. Further preferably, the calcination is carried out in stages. The specific process is: first calcine the mixed powder at a temperature of 450-650 °C, and then calcine it at a temperature of 930-1000 °C to ensure that the metallic zinc is completely volatilized. Specifically, the mixed powder is first heated to 450-650 °C at a heating rate of 3-10 °C·min -1 in argon, and kept for 2 h; then heated to 930-1000 °C at a heating rate of 3-10 °C·min -1 in argon, and kept for 1 h. After the calcination is completed, it can be cooled to room temperature naturally.

[0008] In the above solution, the reason for adding the zinc carbonate lies in its unique chemical structure and properties. The zinc carbonate is easily decomposed by heat. In the subsequent calcination process, it plays an important role. The substances generated by its decomposition can act as a structure-directing agent and a pore regulator in the catalyst system. Specifically, its decomposition process is as follows: first decompose into carbon dioxide and zinc oxide at the temperature of the first calcination; then, in the second calcination process, zinc oxide uses carbon as a reducing agent to generate metallic zinc, and finally the metallic zinc volatilizes in a high-temperature environment and is thus removed from the system. In this process, zinc oxide helps to construct the porous structure of the catalyst, increase the specific surface area of the catalyst, and thus provide more active sites for the catalytic reaction and improve the activity of the catalyst. On the other hand, it can affect the dispersion state of the metal particles (Fe and Cu) in the catalyst to a certain extent, make the metal particles more evenly distributed in the carbon matrix, and better expose the metal nanoparticles on the surface of the catalyst, enhancing the stability and catalytic performance of the catalyst.

[0009] The present invention also provides an FeCu@N-C Fenton-like catalyst, which is prepared by the preparation method as described above.

[0010] The FeCu@N-C Fenton-like catalyst provided by the present invention has good application prospects in the catalytic degradation of organic pollutants. Its application includes the following steps: adding the FeCu@N-C Fenton-like catalyst to the water to be treated containing organic pollutants, adding hydrogen peroxide as an oxidant, and after the organic pollutants are degraded, filtering to obtain the treated water. This catalyst can be applied to the degradation of organic pollutants in advanced oxidation technology (heterogeneous Fenton-like oxidation reaction). The filtered catalyst can be reused after simple treatment such as drying, and has good cyclic stability.

[0011] The present invention has the following beneficial effects: For the FeCu@N-C Fenton-like catalyst provided by the present invention, by simultaneously introducing Fe and Cu nanoparticles into the catalyst system and utilizing the synergistic promotion effect generated by Fe and Cu, the catalytic performance of the catalyst is significantly improved.

[0012] For the preparation method provided by the present invention, by designing the calcination process as staged calcination to precisely control the reduction timing of ZnO, the specific mechanism is as follows: during the first calcination process, due to the low temperature, ZnO can stably exist; during the second calcination process, due to the high temperature, the strong reducibility of carbon is used to reduce ZnO to Zn, and the second sintering temperature is controlled to be higher than the boiling point of Zn to volatilize Zn, and a uniform pore structure is left after volatilization. If a conventional single-temperature calcination process is adopted, it may cause ZnO to directly sublime rather than fully react with carbon, resulting in insufficient porosity of the final product and low catalyst performance.

[0013] The raw materials adopted by the present invention are cheap and easily available, the operation method is simple, and the synthesis is convenient. The prepared FeCu@N-C catalyst can be applied to heterogeneous Fenton-like oxidation reaction to efficiently degrade organic pollutants. Since this catalyst is simple to prepare, easy to be industrially produced, and has a high degradation efficiency for pollutants, it has extremely high application value in the treatment of organic pollutant wastewater. Description of the Drawings

[0014] Figure 1 SEM and HR-TEM spectra of the FeCu@N-C catalyst prepared in Example 1.

[0015] Figure 2 Raman spectrum of the FeCu@N-C catalyst prepared in Example 1.

[0016] Figure 3 FT-IR spectrum of the FeCu@N-C catalyst prepared in Example 1.

[0017] Figure 4 Time variation diagram of the degradation of tetracycline by the catalysts prepared in different examples and comparative examples; Figure 5 SEM image of the catalyst prepared as Comparative Example 2. Detailed implementation manners

[0018] The present invention will be further described below in conjunction with specific embodiments, but the substantial content of the present invention is not limited to the following embodiments. The methods are all conventional methods unless otherwise specified, and the materials can all be obtained from public commercial channels unless otherwise specified. Those skilled in the art should know that any simple transformation or substitution based on the substantial content of the present invention belongs to the protection scope required by the present invention.

[0019] Example 1 A preparation method of a FeCu@N-C type Fenton catalyst, comprising the following steps: Step 1: 0.3 mmol of Fe(NO3)2·9H2O, 0.3 mmol of Cu(NO3)2·3H2O, 0.504 g of C6H 12 O6 and 2.2 g of CO(NH2)2 are dissolved in 20 mL of aqueous solution, and heated at 80 °C until the water is evaporated completely, then 1.586 g of basic zinc carbonate is added and ground into powder; Step 2: Transfer the ground powder to a corundum crucible and place it in a tube furnace for roasting. Under argon, heat it at a heating rate of 5 °C·min -1 to 550 °C and hold for 2 h, then heat it at a heating rate of 5 °C·min -1 to 1000 °C and hold for 1 h, and then cool it naturally to room temperature to obtain the target product, denoted as FeCu@N-C.

[0020] Figure 1 SEM and HR-TEM spectra of the FeCu@N-C catalyst prepared in Example 1. Among them, Figure a is the SEM image of FeCu@N-C, Figure b is the partial enlarged view of Figure a, and Figure c is the HR-TEM spectrum of FeCu@N-C. It can be seen from Figure 1 this that iron and copper nanoparticles are loaded on the wrinkled honeycomb-structured N-doped carbon nanosheets.

[0021] Figure 2 Raman spectrum of the FeCu@N-C catalyst prepared in Example 1. Two significant peaks are observed near 1358 and 1589 cm -1 , which respectively represent the degree of point defects (I D ) and graphite structure (I G ). The value of I D / I G is close to 1, indicating that the catalyst synthesized by the method of this patent has good electrical conductivity, which is beneficial to the improvement of catalytic performance.

[0022] Figure 3FT-IR spectrum of the FeCu@N-C catalyst prepared in Example 1. The basic framework structure of the FeCu@N-C catalyst of the present invention can be proven by the FT-IR spectrum.

[0023] The FeCu@N-C catalyst obtained in this example was applied to the degradation of tetracycline in water: 3 mg of the FeCu@N-C catalyst prepared in Example 1 was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 −1. 100 μL of hydrogen peroxide was added, and it was shaken thoroughly in a shaker at 25 °C and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution. The concentration at the time of detection was defined as the measured concentration, and the initial concentration was 5 mg·L -1 −1, then the removal rate = measured concentration / initial concentration.

[0024] Figure 4 Figure a in [reference] shows the degradation results of the catalysts prepared in different examples and comparative examples for tetracycline in the presence of hydrogen peroxide. As can be seen from Figure 4 Figure a in [reference], when the reaction time was 30 min, the removal rate of the catalyst prepared in Example 1 for tetracycline was 63.2%. If only 100 μL of hydrogen peroxide was added without the catalyst of the present invention (marked as the blank group), the removal rate within 30 min was only 0.04%.

[0025] Comparative Example 1 Compared with Example 1, the difference in this comparative example is that 0.3 mmol of Fe(NO3)2·9H2O and 0.3 mmol of Cu(NO3)2·3H2O in Step 1 were replaced with 0.6 mmol of Fe(NO3)2·9H2O, and other processes were the same as those in Example 1; the prepared catalyst was denoted as Fe@N-C.

[0026] The catalyst obtained in this comparative example was applied to the degradation of tetracycline in water: 3 mg of the catalyst prepared in the comparative example was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 −1. 100 μL of hydrogen peroxide was added, and it was shaken thoroughly in a shaker at 25 °C and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution. As can be seen from Figure 4 Figure a in [reference], when the reaction time was 30 min, the removal rate of the catalyst prepared in Comparative Example 1 for tetracycline was 13.2%.

[0027] Comparative Example 2 Compared with Example 1, the difference in this comparative example lies in that 0.3 mmol of Fe(NO3)2·9H2O and 0.3 mmol of Cu(NO3)2·3H2O in Step 1 are replaced with 0.6 mmol of Cu(NO3)2·5H2O, and other processes are the same as those in Example 1; the prepared catalyst is denoted as Cu@N-C.

[0028] The catalyst obtained in this comparative example was applied to the degradation of tetracycline in water: 3 mg of the catalyst prepared in the comparative example was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 −1, 100 μL of hydrogen peroxide was added, and it was shaken well in a shaker at 25 °C and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution. As can be seen from Figure 4 Figure a, when the reaction time was 30 min, the removal rate of tetracycline by the catalyst prepared in Comparative Example 2 was 11.2%.

[0029] Comparative Example 3 Compared with Example 1, the difference in this comparative example lies in that basic zinc carbonate was not added in Step 1, and other processes are the same as those in Example 1.

[0030] Figure 5 Figure c is the scanning electron microscope characterization diagram of the catalyst prepared in Comparative Example 3, and it can be seen that most of the iron and copper nanoparticles are wrapped on the N-doped carbon sheet material, and there is no rich pore structure.

[0031] The catalyst obtained in this comparative example was applied to the degradation of tetracycline in water: 3 mg of the catalyst prepared in the comparative example was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 −1, 100 μL of hydrogen peroxide was added, and it was shaken well in a shaker at 25 °C and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution.

[0032] Figure 4 Figure b shows the degradation result of the catalyst prepared in Comparative Example 3 for tetracycline in the presence of hydrogen peroxide. It can be seen that when the reaction time was 30 min, the removal rate of tetracycline by the catalyst prepared in Comparative Example 3 was 8.6%.

[0033] Example 2: Step 1: 0.2 mmol of Fe(NO3)2·9H2O, 0.4 mmol of Cu(NO3)2·3H2O, 0.504 g of C6H 12 O6 and 2.2 g of CO(NH2)2 were dissolved in 20 mL of aqueous solution, and at 80 °C until the water was evaporated to dryness, 1.586 g of basic zinc carbonate was added and ground into a powder; Step 2: The same as Step 2 in Example 1; the obtained catalyst is denoted as FeCu2@N-C.

[0034] The FeCu2@N-C catalyst obtained in this example was applied to the degradation of tetracycline in water: 3 mg of the FeCu@N-C catalyst prepared in Example 2 was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 100 μL of hydrogen peroxide was added, and the mixture was shaken well in a shaker and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution.

[0035] Figure 4 Figure c shows the degradation results of the catalysts prepared in different examples for tetracycline in the presence of hydrogen peroxide. It can be seen that when the reaction time was 30 min, the removal rate of tetracycline by the catalyst prepared in Example 2 was 63.8%.

[0036] Example 3: Step 1: 0.4 mmol of Fe(NO3)2·9H2O, 0.2 mmol of Cu(NO3)2·3H2O, 0.504 g of C6H 12 O6 and 2.2 g of CO(NH2)2 were dissolved in 20 mL of aqueous solution. It was heated at 80 °C until the water was evaporated, and then 1.586 g of basic zinc carbonate was added and ground into a powder; Step 2: The same as Step 2 in Example 1; the obtained catalyst is denoted as Fe2Cu@N-C.

[0037] The Fe2Cu@N-C catalyst obtained in this example was applied to the degradation of tetracycline in water: 1 mg of the Fe2Cu@N-C catalyst prepared in Example 3 was weighed and added to 50 mL of a water sample with a tetracycline concentration of 5 mg·L -1 100 μL of hydrogen peroxide was added, and the mixture was shaken well in a shaker and sampled and filtered at specific times to detect the remaining content of tetracycline in its aqueous solution. As can be seen from Figure 4 Figure c, when the reaction time was 30 min, the removal rate of tetracycline by the catalyst prepared in Example 3 was 62.5%.

[0038] It should be noted that in other examples, when the experimental process meets the following conditions, the object of the present invention can be achieved: For the temperature of the first calcination, it is preferably 450 - 650 °C, specifically it can be 450 °C, 500 °C or other temperatures such as 650 °C; for the temperature of the second calcination, it is preferably 930 - 1000 °C, specifically it can be 930 °C, 950 °C or other temperatures such as 1000 °C. For the above process parameters, those skilled in the art can make appropriate selections according to actual needs.

[0039] Obviously, the described embodiments are some but not all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

Claims

1. A preparation method of FeCu@N-C Fenton-like catalyst, characterized in that: It includes the following steps: Dissolve a water-soluble iron salt, a water-soluble copper salt, a carbon source and urea in water to obtain a mixed solution; Remove the water in the mixed solution to obtain a solid; Grind and mix the solid with a zinc carbonate evenly to obtain a mixed powder; Calcine the mixed powder in a protective atmosphere to obtain a FeCu@N-C Fenton-like catalyst.

2. The preparation method of the FeCu@N-C class Fenton catalyst according to claim 1, characterized in that: The water-soluble iron salt is iron nitrate or iron chloride.

3. The preparation method of the FeCu@N-C type Fenton catalyst according to claim 1, characterized in that: The water-soluble copper salt is copper nitrate or copper chloride.

4. The preparation method of the FeCu@N-C class Fenton catalyst according to claim 1, characterized in that: The carbon source is glucose.

5. The preparation method of the FeCu@N-C type Fenton catalyst according to any one of claims 1 to 4, characterized in that: The molar ratio of iron in the water-soluble iron salt to copper in the water-soluble copper salt is (0.5 - 2):

1.

6. The preparation method of the FeCu@N-C class Fenton catalyst according to any one of claims 1 to 4, characterized in that: The zinc carbonate is basic zinc carbonate or zinc carbonate.

7. The preparation method of the FeCu@N-C class Fenton catalyst according to claim 1, characterized in that: The calcination process is as follows: first, calcine the mixed powder at a temperature of 450 - 650 °C for the first time, and then calcine it at a temperature of 930 - 1000 °C for the second time.

8. A FeCu@N-C-like Fenton catalyst, characterized in that: It is prepared by using the preparation method described in any one of claims 1 to 7.

9. Use of the FeCu@N-C Fenton-like catalyst according to claim 8 in the catalytic degradation of organic pollutants.

10. The application according to claim 9, wherein: It includes the following steps: Add the FeCu@N-C Fenton-like catalyst according to claim 8 to the water to be treated containing organic pollutants, add hydrogen peroxide as an oxidant, after the organic pollutants are degraded, filter to obtain the treated water.

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