Iron-cobalt-nickel layered double hydroxide / graphite-acetylene nano composite material as well as preparation method and application thereof

Abstract

The invention discloses an iron-cobalt-nickel layered double hydroxide / graphite-alkyne nano composite material and a preparation method and application thereof, and the preparation method comprises the following steps: mixing iron salt, cobalt salt and nickel salt to prepare a precursor solution, adding the precursor solution and an alkaline solution into a graphite-alkyne dispersion liquid, stirring, and carrying out a hydrothermal reaction to obtain the nano composite material. The nano composite material prepared by the invention has the advantages of large specific surface area, good dispersity, multiple reaction active sites, high catalytic activity, good stability and the like, is a novel composite catalyst with excellent catalytic performance and stable structure, can efficiently activate persulfate when being used for activating the persulfate, and has the advantages of simple preparation process, low cost and the like. The constructed degradation system can efficiently degrade various antibiotics, and is high in use value and good in application prospect. Meanwhile, the preparation method has the advantages of being simple in process, convenient to operate, mild in reaction condition, low in cost, environmentally friendly and the like, can be used for large-scale preparation and is convenient for industrial utilization.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of environmental functional nanomaterials, and relates to an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material and a preparation method and application thereof. Background Art

[0002] The Fenton-like technology based on persulfate activation is a new technology for degrading antibiotics. Since the persulfate activation process generates fewer secondary pollutants and has good environmental friendliness, it has become a green pollution control technology. At the same time, in the Fenton-like technology based on persulfate activation, persulfate can generate strong oxidative free radicals (such as sulfate free radicals and hydroxyl free radicals) through catalyst activation, which can then be used to effectively degrade difficult-to-degrade antibiotics such as chloramphenicol and tetracycline. Therefore, the development of high-performance catalysts for activating persulfate is the key.

[0003] Layered double hydroxides, also known as anionic clays or hydrotalcites, are low-toxic, biocompatible, and easily preserved sewage sludge nanomaterials that show great potential in persulfate activation. For example, some researchers have used nickel-iron layered double hydroxide and supported iron-cobalt layered double hydroxide as catalysts to activate persulfate, but the degradation system constructed by these layered double hydroxides and persulfate is still difficult to quickly remove pollutants from water bodies. For example, when nickel-iron layered double hydroxide and persulfate are used to degrade methylene blue, the degradation rate of methylene blue is as high as 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, when the dosage of FeCo-LDH / biochar composite catalyst is 0.3 g / L, it takes 30 minutes to remove 96.63% of tetracycline, which has defects such as large catalyst dosage, low activation efficiency and low treatment efficiency. It can be seen that the above-mentioned layered double hydroxide still has defects such as insufficient activation ability and activation efficiency, making it difficult to achieve efficient activation of persulfate, and further difficult to efficiently remove pollutants in wastewater.

[0004] In addition, there have been no reports on the use of iron-cobalt-nickel layered double hydroxide to activate persulfate. Nevertheless, there are still certain disadvantages when using iron-cobalt-nickel layered double hydroxide monomers to activate persulfate, such as: (1) The surface energy of iron-cobalt-nickel layered double hydroxide is relatively high, and it is easy to agglomerate during the preparation and activation of persulfate, resulting in a large number of active sites being buried; (2) The conductivity of iron-cobalt-nickel layered double hydroxide is relatively poor, which is not conducive to the transfer of electrons to persulfate, resulting in low activation efficiency.

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

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material having large specific surface area, good dispersibility, multiple reaction active sites, high catalytic activity and good stability, as well as a preparation method and application thereof.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material comprises the following steps: S1, mixing iron salt, cobalt salt and nickel salt to prepare a precursor solution; preparing graphite-yne ​​to prepare a graphite-yne ​​dispersion; S2, adding the precursor solution and alkaline solution obtained in step S1 to the graphene-acetylene dispersion obtained in step S1, stirring to obtain a mixed solution; S3, performing a hydrothermal reaction on the mixed solution obtained in step S2 to obtain an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material.

[0008] The above preparation method is further improved in that the ratio of graphene-acetylene to iron salt is 25mg-200mg:3mmol.

[0009] The above preparation method is further improved in that the molar ratio of the iron salt, the cobalt salt and the nickel salt is 3:6:1.

[0010] The above preparation method is further improved, wherein the molar ratio of the iron salt to the alkaline substance in the alkaline solution is 3:200. The above preparation method is further improved, The above preparation method is further improved 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.

[0011] The above preparation method is further improved, in step S1, the preparation method of graphene-acetylene comprises the following steps: S1-1, mixing benzene and anhydrous ethanol, adding calcium carbide powder to obtain a dispersion; the ratio of the calcium carbide powder, benzene and anhydrous ethanol is 10 g: 2 mL: 35 mL; S1-2, adding the dispersion obtained in step S1-1 and stainless steel beads into a stainless steel ball mill, evacuating the mixture, reacting in a planetary ball mill, washing, and drying; during the reaction, the rotation speed of the planetary ball mill is controlled to be 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 respectively; the drying is performed under vacuum conditions; the drying temperature is 60°C, and the drying time is 12 to 24 h; S1-3, annealing the material dried in step S1-2 to obtain graphene; the heating rate during the annealing process is 5°C / min; the annealing temperature is 260°C; and the annealing time is 2 h.

[0012] The above preparation method is further improved, in step S2, the stirring is carried out at a temperature of 65° C. and the stirring time is 4 hours.

[0013] The above preparation method is further improved, in step S3, the temperature of the hydrothermal reaction is 140° C.; the time of the hydrothermal reaction is 24 h.

[0014] The above preparation method is further improved, and after the hydrothermal reaction is completed, the following treatment is also included: centrifuging the product obtained after the hydrothermal reaction at 8000rpm for 8min, washing the centrifuged product with anhydrous ethanol for 3 to 5 times, and drying it under vacuum conditions at a temperature of 60°C for 12 h to 24 h to obtain an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material.

[0015] As a general technical concept, the present invention also provides an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared by the above-mentioned preparation method, wherein the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material comprises graphite-yne ​​and iron-cobalt-nickel layered double hydroxide, and the graphite-yne ​​is supported on the iron-cobalt-nickel layered double hydroxide; the mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is 3 to 24:100.

[0016] The above-mentioned iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is further improved, wherein the mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is 1-2:10.

[0017] As a general technical concept, the present invention also provides an application of the above-mentioned iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material as a catalyst for activating persulfate in treating antibiotic wastewater.

[0018] The above application is further improved and includes the following steps: mixing the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material with antibiotic wastewater, adding persulfate to carry out a Fenton-like catalytic reaction, and completing the degradation of organic pollutant antibiotics in the wastewater.

[0019] The above application is further improved in that the addition amount of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is 0.05 g to 0.2 g per liter of antibiotic wastewater.

[0020] The above application is further improved in that the amount of persulfate added is 0.1g to 0.5g persulfate per liter of antibiotic wastewater.

[0021] The above application is further improved in that the persulfate is peroxymonosulfate and / or potassium hydrogen persulfate.

[0022] The above application is further improved, wherein the antibiotic in the antibiotic wastewater is tetracycline; and the initial concentration of the antibiotic in the antibiotic wastewater is ≤10 mg / L.

[0023] The above application is further improved in that the time of the Fenton-like catalytic reaction is 6 min to 15 min.

[0024] Compared with the prior art, the advantages of the present invention are: (1) In view of the defects of existing layered double hydroxide catalysts, such as small specific surface area, easy agglomeration, small number of active sites, weak activation ability and low activation efficiency, the present invention creatively proposes a method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material. Graphite-yne, iron salt, cobalt salt and nickel salt are used as raw materials. A precursor solution and an alkaline solution are first added to a graphite-yne ​​dispersion and stirred. During the stirring process, a large amount of metal ions can be uniformly adsorbed on the surface of graphite-yne ​​due to its huge specific surface area and rich adsorption sites, thereby improving the dispersibility of the metal ions. At the same time, the metal ions adsorbed on the surface of graphite-yne ​​react with the hydroxide ions in the system. The ion reaction forms a precursor material and is coated on the surface of graphene, which is the basis for regulating and improving the dispersibility of iron-cobalt-nickel layered double hydroxide. On this basis, the mixed solution is subjected to a hydrothermal reaction. During the hydrothermal process, the metal precursor coated on the surface of graphene is converted into iron-cobalt-nickel layered double hydroxide, and with the help of the abundant highly unsaturated carbon-carbon double bonds on the surface of graphene, as well as the π electron cloud and abundant aromatic rings in the graphene structure, the π electrons of graphene can form π-π interactions with the metal sites in the iron-cobalt-nickel layered double hydroxide. This interaction can promote the transfer of electrons and the regulation of local electron density, thereby improving the metal sites on the surface of the iron-cobalt-nickel layered double hydroxide. At the same time, with the help of the ultra-high specific surface area of ​​graphene-acetylene, it has excellent dispersibility, which can make the iron-cobalt-nickel layered double hydroxide firmly and evenly attached to the surface of graphene-acetylene, and can avoid its agglomeration and aggregation, so as to maintain its high specific surface area and maximize the exposure of metal active sites, thereby improving the activation ability of persulfate and the degradation ability of pollutants. In particular, with the help of the uneven distribution of electrons on the surface of graphene-acetylene, the migration resistance of iron-cobalt-nickel layered double hydroxide on its surface is also increased, which is also conducive to preventing the agglomeration of iron-cobalt-nickel layered double hydroxide, and then can significantly increase the stability and catalytic performance of iron-cobalt-nickel layered double hydroxide, and more importantly, The important thing is that, by means of the high conductivity and excellent carrier migration characteristics possessed by graphene-acetylene, the rapid migration of electrons in the iron-cobalt-nickel layered double hydroxide can be accelerated, and the activation efficiency of persulfate can be greatly improved, thereby preparing an iron-cobalt-nickel layered double hydroxide / graphene-acetylene nanocomposite material with large specific surface area, good dispersibility, multiple reactive sites, high catalytic activity and good stability, which is a novel composite catalyst with excellent catalytic performance and stable structure. When the composite material is used to activate persulfate, persulfate can be efficiently activated under the joint action of graphene-acetylene and iron-cobalt-nickel layered double hydroxide, and the constructed degradation system can efficiently degrade antibiotics, with high use value and good 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, green environmental protection, etc., and can be used for large-scale preparation, which is convenient for industrial utilization.

[0025] (2) In the preparation method of the present invention, by optimizing the ratio of graphene-acetylene to iron salt to 25 mg to 200 mg: 3 mmol, the prepared iron-cobalt-nickel layered double hydroxide / graphene-acetylene nanocomposite material has a moderate content of graphene-acetylene and better dispersibility of the iron-cobalt-nickel layered double hydroxide, has more excellent catalytic performance and a more stable structure, and can meet different application requirements.

[0026] (3) The present invention provides an application of an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material as a catalyst for activating persulfate in treating organic pollutant wastewater. Specifically, the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared by the present invention has a large specific surface area, good dispersibility, many reaction active sites, high catalytic activity and good stability. As a catalyst for activating persulfate, the persulfate can be activated to rapidly form a large number of free radicals with strong oxidizing effects (such as sulfate radicals and hydroxyl radicals). In the degradation system constructed in this way, these free radicals with strong oxidizing effects can be used to achieve efficient degradation of different types of antibiotics in wastewater. The method has the advantages of simple process, convenient operation, low cost, high treatment efficiency, good removal effect and green environmental protection, and is of great significance for purifying antibiotic wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0028] Figure 1 This is a transmission electron micrograph of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention.

[0029] Figure 2 This is the X-ray diffraction pattern of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention.

[0030] Figure 3 This is the energy spectrum of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention.

[0031] Figure 4 This is a graph showing the degradation effects of iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposites (A1, A2, A3, A4), iron-cobalt-nickel layered double hydroxide, and graphite-yne ​​on tetracycline in Example 5 of the present invention.

[0032] Figure 5 This is a diagram showing the cyclic degradation effect of tetracycline on the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material (A3) in Example 5 of the present invention. DETAILED DESCRIPTION

[0033] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the protection scope of the present invention is not limited thereby.

[0034] In the following examples 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.

[0035] Example 1 A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-acetylene nanocomposite material comprises the following steps: 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-acetylene to 150 mL of ultrapure water and disperse by ultrasonic for 1 h to prepare a graphene-acetylene dispersion.

[0036] The preparation method of graphene-acetylene used is: 2 mL of benzene and 35 mL of ethanol were added to a 250 mL stainless steel ball mill, and then 10 g of calcium carbide powder was added to the mixed solution. Then the mixture of the three and the stainless steel beads were added to the stainless steel ball mill, the lid was closed and vacuumed. Then the ball mill was placed on a planetary ball mill and run at 600 rpm for 24 h (resting for 3 min every 6 min to prevent overheating). The obtained material was then washed with nitric acid and glacial acetic acid for 3-5 times, and the washed material was dried in a vacuum drying oven (60 ° C). The dried material was placed in a tubular furnace, and the tubular furnace was heated to 260 ° C at a heating rate of 5 ° C / min, and then annealed at 260 ° C for 2 h to obtain graphene.

[0037] S2. Add the precursor solution and alkaline solution (sodium hydroxide solution) obtained in step S1 to the graphene-acetylene dispersion obtained in step S1, and stir vigorously at 65° C. for 4 h to obtain a mixed solution.

[0038] S3. The mixed solution obtained in step S2 is placed in a reactor, and a hydrothermal reaction is carried out at 140° C. for 24 h. The product obtained after the hydrothermal reaction is centrifuged at 8000 rpm for 8 min. The centrifuged product is washed with anhydrous ethanol for 5 times, and dried at 60° C. under vacuum conditions for 12 h to obtain an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material, which is numbered A1.

[0039] The iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in this embodiment includes graphite-yne ​​and iron-cobalt-nickel layered double hydroxide, and graphite-yne ​​is loaded on the iron-cobalt-nickel layered double hydroxide; the mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is 3:100.

[0040] Example 2 A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is substantially the same as that of Example 1, except that in Example 2, the amount of graphite-yne ​​used is 75 mg.

[0041] The iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 2 is denoted as A2.

[0042] The mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 2 is 9:100.

[0043] Example 3 A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is substantially the same as that in Example 1, except that in Example 3, the amount of graphite-yne ​​used is 150 mg.

[0044] The iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 is denoted as A3.

[0045] The mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 is 9:50.

[0046] Example 4 A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is substantially the same as that of Example 1, except that in Example 4, the amount of graphite-yne ​​used is 200 mg.

[0047] The iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 4 is denoted as A4.

[0048] The mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 4 is 12:50.

[0049] Comparative Example 1 A method for preparing an iron-cobalt-nickel layered double hydroxide comprises the following steps: (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.

[0050] (2) Add the precursor solution obtained in step (1) into an alkaline solution (sodium hydroxide solution), and vigorously stir the mixture at 65° C. for 4 h to obtain a mixed solution.

[0051] (3) The mixed solution obtained in step (2) is placed in a reactor and subjected to a hydrothermal reaction at 140° C. for 24 h. The product obtained after the hydrothermal reaction is centrifuged at 8000 rpm for 8 min. The centrifuged product is washed with anhydrous ethanol for 5 times and dried at 60° C. under vacuum conditions for 12 h to obtain an iron-cobalt-nickel layered double hydroxide.

[0052] Figure 1 FIG. 1 is a transmission electron microscope image of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention. Figure 1 It can be seen that some nanomaterials grow on the surface of the iron-cobalt-nickel layered double hydroxide, which are graphene-acetylene.

[0053] Figure 2 : is the X-ray diffraction pattern of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention. Figure 2 It can be seen that the composite material has a diffraction peak corresponding to iron-cobalt-nickel layered double hydroxide.

[0054] Figure 3 : is the energy spectrum of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared in Example 3 of the present invention. Figure 3 It can be seen that the composite material contains carbon, oxygen, iron, cobalt and nickel.

[0055] The above test results can prove that the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material has been successfully prepared.

[0056] Example 5 An application of an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material as a catalyst for activating persulfate in treating antibiotic wastewater, specifically: using the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material (A1, A2, A3, A4) prepared in Examples 1-4 as a catalyst for activating persulfate to treat tetracycline wastewater, comprising the following steps: 0.01 g of graphite-yne, iron-cobalt-nickel layered double hydroxide, and iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposites (A1, A2, A3, and A4) were accurately weighed and added into 100 mL and 10 mg / L tetracycline solutions, respectively. The solutions were magnetically stirred for 30 min in the dark to allow tetracycline to reach adsorption-desorption equilibrium on different catalyst surfaces. 30 mg of persulfate (potassium hydrogen persulfate) was added for a Fenton-like catalytic reaction for 12 min to complete the degradation of tetracycline in the wastewater.

[0057] During the Fenton-like catalytic reaction, 3 mL of the solution was taken every 2 min (a total of 12 min of sampling), and 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 by a UV-visible spectrophotometer, and the degradation efficiency of different catalysts was calculated. The results are shown in Figure 2. Figure 4 shown.

[0058] Figure 4 The figure shows the degradation effect of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite materials (A1, A2, A3, A4), the iron-cobalt-nickel layered double hydroxide, and graphite-yne ​​on tetracycline in Example 5 of the present invention. Figure 4It can be seen that graphene has the worst effect, with a tetracycline removal rate of only 23.78% after 12 minutes of reaction. At the same time, the removal rate of tetracycline by iron-cobalt-nickel layered double hydroxide is also less than 70% after 12 minutes of reaction. Different from them, with the addition of graphene, the catalytic degradation effect of iron-cobalt-nickel layered double hydroxide / graphene-yne ​​nanocomposite material on tetracycline is getting better and better, and with the increase of graphene-yne ​​content, the catalytic degradation effect continues to increase. When the mass ratio of graphene-yne ​​to iron-cobalt-nickel layered double hydroxide is 9:50, the corresponding iron-cobalt-nickel layered double hydroxide / graphene-yne ​​nanocomposite material (A3) has the best degradation effect on tetracycline, with a tetracycline removal rate of more than 90% after 6 minutes of reaction, and a tetracycline removal rate of 98.21% after 12 minutes of reaction. This is because the presence of graphene provides abundant active sites and enhances electron mobility, significantly improving the activation ability and activation efficiency of the composite material for persulfate. However, if the content of graphite-yne ​​continues to increase, the effect of the composite material will decrease instead, because too much graphite-yne ​​will not form an effective composite material with the iron-cobalt-nickel layered double hydroxide, and the catalytic performance of the graphite-yne ​​monomer is poor, which leads to a decrease in the performance of the entire composite material. Therefore, in the present invention, by optimizing the mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material to 3-24:100, in particular, the mass ratio of the two is 1-2:10, the corresponding iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material has a moderate content of graphite-yne ​​and better dispersibility of the iron-cobalt-nickel layered double hydroxide, has more excellent catalytic performance and a more stable structure, and can meet different application requirements.

[0059] In this example, the repeated treatment effect of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material (A3) on tetracycline was also investigated. Specifically, the tetracycline solution was repeatedly degraded using the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material (A3). Other conditions were the same. The results are as follows: Figure 5 shown.

[0060] Figure 5 The figure is a graph showing the cyclic degradation effect of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material (A3) on tetracycline in Example 5 of the present invention. Figure 5 It can be seen from the five-cycle experiment that the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material has a high reusability, and after the fifth cycle, it still has a degradation effect of 89.86%. It can be seen that the repeated treatment of antibiotic wastewater with the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material can significantly reduce the treatment cost of antibiotic wastewater and facilitate its popularization and use.

[0061] As can be seen from the above results, compared with conventional methods, the preparation method of the iron-cobalt-nickel layered double hydroxide / graphite-alkyne nanocomposite material of the present invention, with graphite-alkyne, iron salt, cobalt salt, nickel salt as raw materials, successively through stirring, hydrothermal reaction, can prepare the iron-cobalt-nickel layered double hydroxide / graphite-alkyne nanocomposite material with large specific surface area, good dispersibility, many reactive sites, high catalytic activity, good stability, this is a novel composite catalyst with excellent catalytic performance and stable structure, when the composite material is used to activate persulfate, persulfate can be efficiently activated under the joint action of graphite-alkyne and iron-cobalt-nickel layered double hydroxide, and the constructed degradation system can efficiently degrade antibiotics, with high use value and good 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, green environmental protection, etc., can be used for large-scale preparation, and is convenient for industrial utilization.

[0062] The above embodiments are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material, characterized in that: The following steps are involved: S1, mixing iron salt, cobalt salt and nickel salt to prepare a precursor solution; preparing graphite-yne ​​to prepare a graphite-yne ​​dispersion; S2, adding the precursor solution and alkaline solution obtained in step S1 to the graphene-acetylene dispersion obtained in step S1, stirring to obtain a mixed solution; S3, performing a hydrothermal reaction on the mixed solution obtained in step S2 to obtain an iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material.

2. The preparation method according to claim 1, characterized in that The ratio of graphene to iron salt is 25mg-200mg:3mmol; the molar ratio of iron salt, cobalt salt and nickel salt is 3:6:1; the molar ratio of iron salt to alkaline substance in 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-acetylene comprises the following steps: S1-1, mixing benzene and anhydrous ethanol, adding calcium carbide powder to obtain a dispersion; the ratio of the calcium carbide powder, benzene and anhydrous ethanol is 10 g: 2 mL: 35 mL; S1-2, adding the dispersion obtained in step S1-1 and stainless steel beads into a stainless steel ball mill, evacuating the mixture, reacting in a planetary ball mill, washing, and drying; during the reaction, the rotation speed of the planetary ball mill is controlled to be 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 respectively; the drying is performed under vacuum conditions; the drying temperature is 60°C, and the drying time is 12 to 24 h; S1-3, annealing the material dried in step S1-2 to obtain graphene; the heating rate during the annealing process is 5°C / min; the annealing temperature is 260°C; 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 S2, the stirring is performed at a temperature of 65° C. and the stirring time is 4 hours; In step S3, the temperature of the hydrothermal reaction is 140°C; the time of the hydrothermal reaction is 24 hours; after the completion of the hydrothermal reaction, the following treatment is also included: centrifuging the product obtained after the hydrothermal reaction at 8000rpm for 8 minutes, washing the centrifuged product with anhydrous ethanol for 3 to 5 times, and drying it under vacuum conditions at a temperature of 60°C for 12 hours to 24 hours to obtain a precursor material.

6. An iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material comprises graphite-yne ​​and iron-cobalt-nickel layered double hydroxide, wherein the graphite-yne ​​is supported on the iron-cobalt-nickel layered double hydroxide; and the mass ratio of graphite-yne ​​to iron-cobalt-nickel layered double hydroxide in the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material is 3-24:

100.

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

10.

8. Use of the iron-cobalt-nickel layered double hydroxide / graphite-yne ​​nanocomposite material as claimed in claim 6 or 7 as a catalyst for activating persulfate in treating antibiotic wastewater.

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

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

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