Iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposites, their preparation methods and applications

Abstract

This invention discloses an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material, its preparation method, and its applications. The preparation method includes the following steps: mixing iron salt, cobalt salt, and nickel salt to prepare a precursor solution, adding it and an alkaline solution to a graphite-acetylene dispersion, stirring, and performing a hydrothermal reaction to obtain the nanocomposite material of this invention. The nanocomposite material prepared by this invention has advantages such as large specific surface area, good dispersibility, multiple reactive sites, high catalytic activity, and good stability. It is a novel composite catalyst with excellent catalytic performance and stable structure. When used to activate persulfate, it can efficiently activate persulfate. The constructed degradation system can efficiently degrade various antibiotics, showing high use value and promising application prospects. Furthermore, the preparation method of this invention also has advantages such as simple process, convenient operation, mild reaction conditions, low cost, and environmental friendliness, making it suitable for large-scale preparation and industrial application.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional nanomaterial preparation technology, and relates to an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material, its preparation method and application. Background Technology

[0002] Persulfate-activated Fenton-like technology is a novel technique for degrading antibiotics. Because the persulfate activation process generates fewer secondary pollutants, it is environmentally friendly and thus a green pollution control technology. Furthermore, in this technology, the activation of persulfate through a catalyst generates strong oxidizing radicals (such as sulfate radicals and hydroxyl radicals), which can then be used to effectively degrade recalcitrant antibiotics, such as chloramphenicol and tetracycline. Therefore, developing high-performance catalysts for persulfate activation is crucial.

[0003] Layered double hydroxides, also known as anionic clays or hydrotalcites, are low-toxicity, biocompatible, and easy-to-store sludge nanomaterials that have shown great potential in persulfate activation. For example, researchers have used nickel-iron layered double hydroxides and supported iron-cobalt layered double hydroxides as catalysts to activate persulfate. However, the degradation systems constructed from these layered double hydroxides and persulfate are still insufficient for rapidly removing pollutants from water. For instance, when nickel-iron layered double hydroxides and persulfate are used to degrade methylene blue, the highest degradation rate is 86.2% after 120 minutes of reaction. When supported FeCo-LDH@silica heterogeneous persulfate activator and persulfate are used to degrade tetracycline, the removal rate of TC solution is 66.7%. When FeCo-LDH / biochar composite catalyst is used to activate persulfate to degrade tetracycline, it takes 30 minutes to remove 96.63% of tetracycline when the amount of FeCo-LDH / biochar composite catalyst is 0.3 g / L, resulting in drawbacks such as large catalyst dosage, low activation efficiency, and low treatment efficiency. It is evident that the aforementioned layered double hydroxides still suffer from defects such as insufficient activation capacity and activation efficiency, making it difficult to achieve efficient activation of persulfate and thus difficult to efficiently remove pollutants from wastewater.

[0004] In addition, there have been no reports to date on the activation of persulfate using iron-cobalt-nickel layered double hydroxides. Nevertheless, there are still some disadvantages to using iron-cobalt-nickel layered double hydroxide monomers to activate persulfate, such as: (1) the surface energy of iron-cobalt-nickel layered double hydroxides is relatively high, and they are prone to agglomeration during the preparation and activation of persulfate, resulting in the burial of a large number of active sites; (2) the conductivity of iron-cobalt-nickel layered double hydroxides is relatively poor, which is not conducive to electron transport to persulfate, thus resulting in low activation efficiency.

[0005] Therefore, obtaining a layered iron-cobalt-nickel double hydroxide catalyst with large specific surface area, good dispersibility, multiple reactive sites, high catalytic activity, and good stability is of great significance for effectively activating persulfate and achieving efficient removal of antibiotics from water. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material with large specific surface area, good dispersibility, many reactive sites, high catalytic activity, and good stability, as well as its preparation method and application.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for preparing an iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material includes the following steps:

[0009] S1. Prepare a precursor solution by mixing iron salts, cobalt salts, and nickel salts; prepare a graphene-1,2 ...

[0010] S2. Add the precursor solution and alkaline solution obtained in step S1 to the graphite-acetylene dispersion obtained in step S1, stir, and obtain a mixture.

[0011] S3. The mixture obtained in step S2 is subjected to a hydrothermal reaction to obtain an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material.

[0012] In a further improvement to the above preparation method, the ratio of graphene to iron salt is 25 mg to 200 mg: 3 mmol.

[0013] In a further improvement to the above preparation method, the molar ratio of the iron salt, cobalt salt, and nickel salt is 3:6:1.

[0014] In a further improvement to the above preparation method, the molar ratio of the iron salt to the alkaline substance in the alkaline solution is 3:200. In a further improvement to the above preparation method...

[0015] In a further improvement to the above preparation method, the iron salt is ferric chloride; the cobalt salt is cobalt chloride; the nickel salt is nickel chloride; and the alkaline solution is sodium hydroxide solution.

[0016] In a further improvement to the above preparation method, step S1 of the preparation method of graphene-1, includes the following steps:

[0017] S1-1. Mix benzene and anhydrous ethanol, add calcium carbide powder to obtain a dispersion; the ratio of calcium carbide powder, benzene and anhydrous ethanol is 10 g: 2 mL: 35 mL.

[0018] S1-2. The dispersion obtained in step S1-1 and stainless steel beads are added to a stainless steel ball mill jar, vacuum is applied, and the reaction is carried out in a planetary ball mill. The mixture is then washed and dried. During the reaction, the rotation speed of the planetary ball mill is controlled at 600 rpm. The reaction time is 24 h. The washing is performed by washing with nitric acid and glacial acetic acid 3 to 5 times each. The drying is carried out under vacuum conditions at a temperature of 60 ℃ for 12 to 24 h.

[0019] S1-3. Anneal the dried material from step S1-2 to obtain graphene; the heating rate during the annealing process is 5 ℃ / min; the annealing temperature is 260 ℃; and the annealing time is 2 h.

[0020] In a further improvement to the above preparation method, in step S2, the stirring is carried out at a temperature of 65°C and the stirring time is 4 hours.

[0021] In a further improvement to the above preparation method, in step S3, the temperature of the hydrothermal reaction is 140 °C, and the time of the hydrothermal reaction is 24 h.

[0022] The above preparation method is further improved by including the following treatment after the hydrothermal reaction: centrifuging the product obtained after the hydrothermal reaction at 8000 rpm for 8 min, washing the centrifuged product with anhydrous ethanol 3 to 5 times, and drying it under vacuum at 60°C for 12 to 24 h to obtain the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material.

[0023] As a general technical concept, the present invention also provides an iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material prepared by the above-described preparation method, wherein the iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material comprises graphene and iron-cobalt-nickel layered double hydroxide, wherein the graphene is loaded on the iron-cobalt-nickel layered double hydroxide; the mass ratio of graphene to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material is 3-24:100.

[0024] In a further improvement of the aforementioned iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material, the mass ratio of graphite-acetylene to iron-cobalt-nickel layered double hydroxide is 1 to 2:10.

[0025] As a general technical concept, the present invention also provides the application of the above-mentioned iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material as a catalyst for activating persulfate in the treatment of antibiotic wastewater.

[0026] Further improvements to the above application include the following steps: mixing iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material with antibiotic wastewater, adding persulfate to carry out a Fenton-like catalytic reaction, and completing the degradation of organic pollutants such as antibiotics in the wastewater.

[0027] In a further improvement to the above application, the amount of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material added is 0.05g to 0.2g per liter of antibiotic wastewater.

[0028] In a further improvement to the above application, the amount of persulfate added is 0.1g to 0.5g per liter of antibiotic wastewater.

[0029] In a further improvement to the above application, the persulfate is permonosulfate and / or potassium peroxymonosulfate.

[0030] In a further improvement to the above application, the antibiotic in the antibiotic wastewater is tetracycline; and the initial concentration of the antibiotic in the antibiotic wastewater is ≤10 mg / L.

[0031] In the above-described application, a further improvement is made, wherein the time for the Fenton-like catalytic reaction is 6 min to 15 min.

[0032] Compared with the prior art, the advantages of the present invention are as follows:

[0033] (1) In view of the defects of existing layered double hydroxide catalysts, such as small specific surface area, easy agglomeration, few active sites, weak activation ability and low activation efficiency, this invention creatively proposes a method for preparing iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material. Using graphene, iron salt, cobalt salt and nickel salt as raw materials, the precursor solution and alkaline solution are first added to the graphene dispersion and stirred. During the stirring process, with the help of the huge specific surface area and rich adsorption sites of graphene, a large number of metal ions can be uniformly adsorbed on the surface of graphene, which can improve the dispersibility of metal ions. At the same time, the metal ions adsorbed on the surface of graphene react with hydroxide ions in the system. Ionic reactions form precursor materials that coat the surface of graphdiyne, which is the basis for regulating and improving the dispersibility of iron-cobalt-nickel layered double hydroxides. Based on this, a hydrothermal reaction is carried out on the mixture. During the hydrothermal process, the metal precursor coated on the graphdiyne surface is converted into iron-cobalt-nickel layered double hydroxides. Furthermore, thanks to the abundant highly unsaturated carbon-carbon double bonds on the graphdiyne surface, as well as the π-electron cloud and abundant aromatic rings in the graphdiyne structure, π-π interactions can form between the π electrons of graphdiyne and the metal sites in the iron-cobalt-nickel layered double hydroxides. This interaction promotes electron transfer and regulates the local electron density, thereby improving the dispersibility of the metal sites on the surface of the iron-cobalt-nickel layered double hydroxides. The activity of graphene-1, coupled with its ultra-high specific surface area, gives it excellent dispersibility, allowing iron-cobalt-nickel layered double hydroxides to adhere firmly and uniformly to its surface. This prevents aggregation and maintains a high specific surface area, maximizing the exposure of metal active sites and thus enhancing the activation capacity of persulfate and the degradation capacity of pollutants. In particular, the uneven electron distribution on the graphene-1 surface increases the migration resistance of iron-cobalt-nickel layered double hydroxides, further preventing aggregation and significantly increasing their stability and catalytic performance. Importantly, by leveraging the high conductivity and excellent carrier migration characteristics of graphdiyne, the rapid electron migration in iron-cobalt-nickel layered double hydroxides can be accelerated, significantly improving the activation efficiency of persulfate. This leads to the preparation of an iron-cobalt-nickel layered double hydroxide / graphdiyne nanocomposite material with a large specific surface area, good dispersibility, numerous reactive sites, high catalytic activity, and good stability. This is a novel composite catalyst with excellent catalytic performance and stable structure. When used to activate persulfate, this composite material can efficiently activate persulfate under the combined action of graphdiyne and iron-cobalt-nickel layered double hydroxides. Furthermore, the constructed degradation system can efficiently degrade antibiotics, demonstrating high value and promising application prospects. Simultaneously, the preparation method of this invention also has advantages such as simple process, convenient operation, mild reaction conditions, low cost, and environmental friendliness, making it suitable for large-scale preparation and industrial application.

[0034] (2) In the preparation method of the present invention, by optimizing the ratio of graphene to iron salt to 25mg~200mg∶3 mmol, the graphene content in the prepared iron cobalt nickel layered double hydroxide / graphene nanocomposite material is moderate and the dispersion of iron cobalt nickel layered double hydroxide is better, which has better catalytic performance and more stable structure, and can meet different application requirements.

[0035] (3) This invention provides an application of an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material as a catalyst for activating persulfate in the treatment of organic pollutant wastewater. Specifically, the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in this invention, which has a large specific surface area, good dispersibility, many reactive sites, high catalytic activity, and good stability, is used as a catalyst for activating persulfate. Under the activation of this catalyst, persulfate can rapidly form a large number of free radicals with strong oxidizing effects (such as sulfate free radicals and hydroxyl free radicals). In the degradation system constructed therefrom, these free radicals with strong oxidizing effects can be used to achieve efficient degradation of different types of antibiotics in wastewater. It has the advantages of simple process, convenient operation, low cost, high treatment efficiency, good removal effect, and green environmental protection, and has important promoting significance for the purification of antibiotic wastewater. Attached Figure Description

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0037] Figure 1 This is a transmission electron microscope (TEM) image of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of the present invention.

[0038] Figure 2 The image shows the X-ray diffraction pattern of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of this invention.

[0039] Figure 3 The energy spectrum of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of this invention is shown.

[0040] Figure 4 The diagram shows the degradation effect of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite materials (A1, A2, A3, A4), iron-cobalt-nickel layered double hydroxide, and graphite-acetylene on tetracycline in Example 5 of the present invention.

[0041] Figure 5 This is a diagram showing the cyclic degradation effect of tetracycline on the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material (A3) in Example 5 of the present invention. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0043] In the following embodiments of the present invention, unless otherwise specified, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0044] Example 1

[0045] A method for preparing an iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material includes the following steps:

[0046] S1. Dissolve 3.0 mmol of ferric chloride hexahydrate, 6.0 mmol of cobalt chloride hexahydrate, and 1.0 mmol of nickel chloride hexahydrate in 100 mL of ultrapure water to prepare a precursor solution; dissolve 0.2 mol of NaOH in 100 mL of ultrapure water to prepare a sodium hydroxide solution; add 25 mg of graphene to 150 mL of ultrapure water and sonicate for 1 h to prepare a graphene dispersion.

[0047] The method used to prepare graphene is as follows:

[0048] 2 mL of benzene and 35 mL of ethanol were added to a 250 mL stainless steel ball mill jar. Then, 10 g of calcium carbide powder was added to the mixture. The mixture of these three components, along with stainless steel beads, was then added to the jar. The jar was sealed and a vacuum was applied. The jar was then placed in a planetary ball mill and run at 600 rpm for 24 hours (with a 3-minute break every 6 minutes to prevent overheating). The resulting material was then washed 3-5 times with nitric acid and glacial acetic acid. The cleaned material was dried in a vacuum drying oven (60°C). The dried material was then placed in a tube furnace, where the temperature was increased to 260°C at a rate of 5°C / min, and then annealed at 260°C for 2 hours to obtain graphityne.

[0049] S2. Add the precursor solution and alkaline solution (sodium hydroxide solution) obtained in step S1 to the graphite-acetylene dispersion obtained in step S1, and stir vigorously at 65°C for 4 h to obtain a mixture.

[0050] S3. The mixture obtained in step S2 is placed in a reaction vessel and subjected to hydrothermal reaction at 140℃ for 24 h. The product obtained after hydrothermal reaction is centrifuged at 8000 rpm for 8 min. The product after centrifugation is washed 5 times with anhydrous ethanol and dried under vacuum at 60℃ for 12 h to obtain iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material, numbered A1.

[0051] The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in this embodiment includes graphite-acetylene and iron-cobalt-nickel layered double hydroxide, with graphite-acetylene loaded on the iron-cobalt-nickel layered double hydroxide; the mass ratio of graphite-acetylene to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material is 3:100.

[0052] Example 2

[0053] The preparation method of an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material is basically the same as that in Example 1, except that the amount of graphite-acetylene used in Example 2 is 75 mg.

[0054] The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 2 is denoted as A2.

[0055] In Example 2, the mass ratio of graphene to iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material was 9:100.

[0056] Example 3

[0057] The preparation method of an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material is basically the same as that in Example 1, except that the amount of graphite-acetylene used in Example 3 is 150 mg.

[0058] The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 is denoted as A3.

[0059] In Example 3, the mass ratio of graphene to iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material was 9:50.

[0060] Example 4

[0061] The preparation method of an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material is basically the same as that in Example 1, except that the amount of graphite-acetylene used in Example 4 is 200 mg.

[0062] The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 4 is denoted as A4.

[0063] In Example 4, the mass ratio of graphene to iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material was 12:50.

[0064] Comparative Example 1

[0065] A method for preparing an iron-cobalt-nickel layered double hydroxide includes the following steps:

[0066] (1) Dissolve 3.0 mmol of ferric chloride hexahydrate, 6.0 mmol of cobalt chloride hexahydrate and 1.0 mmol of nickel chloride hexahydrate in 100 mL of ultrapure water to prepare a precursor solution; dissolve 0.2 mol of NaOH in 100 mL of ultrapure water to prepare a sodium hydroxide solution.

[0067] (2) Add the precursor solution obtained in step (1) to an alkaline solution (sodium hydroxide solution) and stir vigorously at 65°C for 4 h to obtain a mixture.

[0068] (3) The mixture obtained in step (2) was placed in a reaction vessel and subjected to hydrothermal reaction at 140°C for 24 h. The product obtained after hydrothermal reaction was centrifuged at 8000 rpm for 8 min. The product after centrifugation was washed 5 times with anhydrous ethanol and dried under vacuum at 60°C for 12 h to obtain iron-cobalt-nickel layered double hydroxide.

[0069] Figure 1 This is a transmission electron microscope (TEM) image of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of this invention. From... Figure 1 It can be seen that some nanomaterials, namely graphene, grow on the surface of the iron-cobalt-nickel layered double hydroxide.

[0070] Figure 2 This is the X-ray diffraction pattern of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of this invention. From... Figure 2 As can be seen, the composite material has diffraction peaks corresponding to the iron-cobalt-nickel layered double hydroxide.

[0071] Figure 3 This is the energy spectrum of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material prepared in Example 3 of this invention. From... Figure 3 It can be seen that the composite material contains carbon, oxygen, iron, cobalt and nickel.

[0072] The above test results prove that the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material has been successfully prepared.

[0073] Example 5

[0074] The application of an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material as a catalyst for activating persulfate in the treatment of antibiotic wastewater specifically involves using the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite materials (A1, A2, A3, A4) prepared in Examples 1-4 as a catalyst for activating persulfate to treat tetracycline wastewater, including the following steps:

[0075] Accurately weigh 0.01 g of graphene, iron-cobalt-nickel layered double hydroxide, and iron-cobalt-nickel layered double hydroxide / graphene nanocomposite materials (A1, A2, A3, A4), and add them to 100 mL and 10 mg / L tetracycline solutions, respectively. Stir magnetically for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on different catalyst surfaces. Add 30 mg of persulfate (potassium peroxymonosulfate) to each catalyst and carry out a Fenton-like catalytic reaction for 12 min to complete the degradation of tetracycline in wastewater.

[0076] During the Fenton-like catalytic reaction, 3 mL of solution was sampled every 2 min (for a total of 12 min). The solution was filtered through a 0.22 µm organic phase filter membrane to remove the catalyst. The concentration of tetracycline in the filtered sample was measured using a UV-Vis spectrophotometer, and the degradation efficiency of different catalysts was calculated. The results are as follows: Figure 4 As shown.

[0077] Figure 4 This image shows the degradation effect of the iron-cobalt-nickel layered double hydroxide / graphite-pyridylene nanocomposite materials (A1, A2, A3, A4), iron-cobalt-nickel layered double hydroxide, and graphite-pyridylene on tetracycline in Example 5 of this invention. Figure 4It can be seen that graphene-1,000 showed the worst effect, with a tetracycline removal rate of only 23.78% after 12 minutes of reaction. Similarly, the iron-cobalt-nickel layered double hydroxide also showed a tetracycline removal rate of less than 70% after 12 minutes of reaction. In contrast, the catalytic degradation effect of the iron-cobalt-nickel layered double hydroxide / graphene-1,000 nanocomposite material on tetracycline improved with the addition of graphene-1,000, and the catalytic degradation effect increased continuously with the increase of graphene-1,000 content. When the mass ratio of graphene-1,000 to iron-cobalt-nickel layered double hydroxide was 9:50, the corresponding iron-cobalt-nickel layered double hydroxide / graphene-1,000 nanocomposite material (A3) showed the best tetracycline degradation effect, with a tetracycline removal rate exceeding 90% after 6 minutes of reaction and reaching 98.21% after 12 minutes. This is because the presence of graphene-1,000 provided abundant active sites and enhanced electron mobility, significantly improving the activation ability and efficiency of the composite material for persulfate. However, further increasing the content of graphene-1,5-di(t)-1 (P2T) actually reduces the effectiveness of the composite material. This is because excessive P2T will not form an effective composite material with the iron-cobalt-nickel layered double hydroxide, and the poor catalytic performance of the P2T monomer leads to a decline in the overall performance of the composite material. Therefore, in this invention, by optimizing the mass ratio of P2T to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / P2T nanocomposite material to 3–24:100, and particularly to 1–2:10, the P2T / P2T nanocomposite material exhibits a moderate content of P2T and better dispersibility of the iron-cobalt-nickel layered double hydroxide, resulting in superior catalytic performance and a more stable structure, thus meeting the needs of different applications.

[0078] In this embodiment, the repeated treatment effect of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material (A3) on tetracycline was also investigated. Specifically, the tetracycline solution was repeatedly degraded using the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material (A3) under the same conditions, and the results are as follows. Figure 5 As shown.

[0079] Figure 5 This image shows the cyclic degradation effect of tetracycline on the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material (A3) in Example 5 of this invention. Figure 5 The results of five cyclic experiments demonstrate that the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material exhibits high reusability, retaining 89.86% degradation efficiency even after the fifth cycle. Therefore, repeatedly treating antibiotic wastewater with this composite material can significantly reduce treatment costs and facilitate widespread application.

[0080] The results above show that, compared with conventional methods, the preparation method of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material of the present invention, using graphite-acetylene, iron salt, cobalt salt, and nickel salt as raw materials, and sequentially through stirring and hydrothermal reaction, can prepare an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material with large specific surface area, good dispersibility, multiple reactive sites, high catalytic activity, and good stability. This is a novel composite catalyst with excellent catalytic performance and stable structure. When this composite material is used to activate persulfate, it can efficiently activate persulfate under the combined action of graphite-acetylene and iron-cobalt-nickel layered double hydroxide. Furthermore, the constructed degradation system can efficiently degrade antibiotics, demonstrating high use value and promising application prospects. At the same time, the preparation method of the present invention also has the advantages of simple process, convenient operation, mild reaction conditions, low cost, and environmental friendliness, making it suitable for large-scale preparation and easy for industrial application.

[0081] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material for activating persulfate-treated antibiotic wastewater, characterized in that, Includes the following steps: S1. A precursor solution is prepared by mixing iron salt, cobalt salt, and nickel salt; a graphene-1,2 ... S2. Add the precursor solution and alkaline solution obtained in step S1 to the graphite-acetylene dispersion obtained in step S1, and stir to obtain a mixture; the stirring is carried out at a temperature of 65°C; the stirring time is 4 hours. S3. The mixture obtained in step S2 is subjected to a hydrothermal reaction to obtain an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material; the temperature of the hydrothermal reaction is 140 ℃; the time of the hydrothermal reaction is 24 h.

2. The preparation method according to claim 1, characterized in that, The molar ratio of the iron salt, cobalt salt, and nickel salt is 3:6:1; the molar ratio of the iron salt to the alkaline substance in the alkaline solution is 3:

200.

3. The preparation method according to claim 2, characterized in that, The iron salt is ferric chloride; the cobalt salt is cobalt chloride; the nickel salt is nickel chloride; and the alkaline solution is sodium hydroxide solution.

4. The preparation method according to any one of claims 1 to 3, characterized in that, In step S1, the method for preparing graphene-1,000 includes the following steps: S1-1. Mix benzene and anhydrous ethanol, add calcium carbide powder to obtain a dispersion; the ratio of calcium carbide powder, benzene and anhydrous ethanol is 10 g: 2 mL: 35 mL. S1-2. The dispersion obtained in step S1-1 and stainless steel beads are added to a stainless steel ball mill jar, vacuum is applied, and the reaction is carried out in a planetary ball mill. The mixture is then washed and dried. During the reaction, the rotation speed of the planetary ball mill is controlled at 600 rpm. The reaction time is 24 h. The washing is performed 3 to 5 times each with nitric acid and glacial acetic acid. The drying is carried out under vacuum conditions at a temperature of 60 ℃ for 12 to 24 h. S1-3. Anneal the dried material from step S1-2 to obtain graphene; the heating rate during the annealing process is 5 ℃ / min; the annealing temperature is 260 ℃; and the annealing time is 2 h.

5. The preparation method according to any one of claims 1 to 3, characterized in that, In step S3, after the hydrothermal reaction is completed, the following treatment is also included: centrifuging the product obtained after the hydrothermal reaction at 8000 rpm for 8 min, washing the centrifuged product with anhydrous ethanol 3 to 5 times, and drying it under vacuum at 60°C for 12 to 24 h.

6. A layered iron-cobalt-nickel double hydroxide / graphite-acetylene nanocomposite material for activating persulfate-treated antibiotic wastewater, prepared by the method according to any one of claims 1 to 5, characterized in that, The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material comprises graphite-acetylene and iron-cobalt-nickel layered double hydroxide, wherein the graphite-acetylene is loaded on the iron-cobalt-nickel layered double hydroxide; the mass ratio of graphite-acetylene to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material is 9-24:

100.

7. The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material according to claim 6, characterized in that, The mass ratio of graphene to iron-cobalt-nickel layered double hydroxide / graphene nanocomposite material is 1 to 2:

10.

8. The application of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material as described in claim 6 or 7 as a catalyst for activating persulfate in the treatment of antibiotic wastewater.

9. The application according to claim 8, characterized in that, Includes the following steps: The iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material was mixed with antibiotic wastewater, and persulfate was added to carry out a Fenton-like catalytic reaction to complete the degradation of the organic pollutant antibiotic in the wastewater. The amount of the iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material added was 0.05g to 0.2g per liter of antibiotic wastewater; the amount of persulfate added was 0.1g to 0.5g per liter of antibiotic wastewater.

10. The application according to claim 9, characterized in that, The persulfate is permonosulfate and / or potassium peroxymonosulfate; the antibiotic in the antibiotic wastewater is tetracycline; the initial concentration of the antibiotic in the antibiotic wastewater is ≤10 mg / L; the time of the Fenton-like catalytic reaction is 6 min to 15 min.

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