Three-dimensional layered double hydroxide, its plasma etching preparation method and application in degrading antibiotics
The preparation of three-dimensional layered bimetallic hydroxides by treating ZIF-67 precursors with dielectric barrier discharge plasma solves the problems of toxic reagents and harsh conditions in the preparation process, and achieves simple, low-cost and efficient antibiotic degradation.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI INSTITUTE OF PHYSICAL SCIENCE CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2023-04-27
- Publication Date
- 2026-07-03
AI Technical Summary
Existing methods for preparing layered bimetallic hydroxides require toxic chemical reagents, are time-consuming and subject to harsh conditions, and have not been effectively applied to antibiotic degradation.
A dielectric barrier discharge plasma was used to treat the ZIF-67 precursor under inert gas conditions, and a three-dimensional layered bimetallic hydroxide was prepared by using an auxiliary etching solution, which simplified the operation and improved the active sites.
The preparation process is simple and low-cost. The three-dimensional layered bimetallic hydroxide has highly active sites that can catalyze the generation of ROS from oxygen and effectively degrade antibiotics.
Smart Images
Figure CN116673034B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of plasma material preparation technology, and relates to a three-dimensional layered bimetallic hydroxide, its plasma etching preparation method, and its application in the degradation of antibiotics. Background Technology
[0002] Layered double hydroxides (LDHs) are hydroxides with a layered crystal structure similar to or similar to hydrotalcite. They are hydroxides composed of two or more metal elements, and the divalent and trivalent metal cations on the main layers can be selectively controlled. Therefore, LDHs are an important inorganic nanomaterial with great potential application value in water pollution treatment, inorganic coatings, industrial molecular sieves, and photoelectrocatalysis.
[0003] Traditional methods for preparing LDH mainly include hydrothermal methods, vapor deposition methods, and coprecipitation methods. However, these methods all have problems such as long processing time, harsh reaction conditions, and high costs. Microplasma-assisted methods are a simple, user-friendly, rapid, energy-saving, and environmentally friendly new method for preparing nanomaterials. Wang et al. used dielectric barrier discharge plasma to prepare two-dimensional ultrathin bimetallic hydroxide nanosheets under inert gas conditions. However, compared with two-dimensional layered nanomaterials, three-dimensional porous nanomaterials have higher catalytic activity due to their higher substrate loading and more active sites.
[0004] Furthermore, the current method of obtaining LDH through plasma treatment requires obtaining the corresponding LDH precursor through high temperature and high pressure reactions, and the plasma treatment time is about half an hour under inert gas conditions. This does not fundamentally solve the problems of harsh reaction conditions and high cost encountered in the preparation of LDH. Therefore, there is an urgent need for a green, efficient, simple and rapid plasma preparation method to obtain three-dimensional layered bimetallic hydroxide nanomaterials with higher active sites.
[0005] In addition, the degradation of antibiotics requires a large amount of resources, and the low degradation efficiency seriously affects people's physical and mental health. Therefore, there is an urgent need for a novel, efficient, convenient, and energy-saving method to process antibiotics.
[0006] Chinese patent application CN115353135A discloses a method for preparing layered bimetallic hydroxides. The method includes the following steps: S1. Preparing a mixed solution of a divalent and a trivalent metal salt, labeled as solution A; preparing a mixed solution of NaNO3 and NaOH, labeled as solution B; S2. Adding solution A dropwise to solution B in a water bath; S3. After the addition is complete, placing the resulting suspension in a hydrothermal reactor and performing a hydrothermal reaction; S4. After the hydrothermal reaction is complete, removing the hydrothermal reactor and cooling it to room temperature, removing the reaction product from the reactor and centrifuging and washing it; S5. Drying the centrifuged and washed sample to obtain layered bimetallic hydroxides. The ZnAl-LDH prepared exhibits the best chloride ion absorption performance when the divalent metal salt is Zn(NO3)2, the trivalent metal salt is Al(NO3)3, and the hydrothermal reaction time is 15 hours. However, this method involves a cumbersome preparation process and complex operation, and it does not disclose the use of layered bimetallic hydroxides for treating antibiotics. Summary of the Invention
[0007] The technical problem to be solved by this invention is how to solve the problems of the need for toxic chemical reagents, excessive preparation time, and harsh preparation conditions in the existing preparation process of layered bimetallic hydroxides.
[0008] The present invention solves the above-mentioned technical problems through the following technical means:
[0009] The first aspect of this invention provides a method for preparing three-dimensional layered bimetallic hydroxides by plasma etching, comprising the following steps:
[0010] (1) Preparation of ZIF-67 precursor: 2-methylimidazole and cobalt nitrate hexahydrate were dissolved in methanol solution, shaken and mixed, allowed to stand, centrifuged to collect the precipitate, washed and dried to obtain ZIF-67 solid.
[0011] (2) Preparation of auxiliary etching solution: Dissolve the ZIF-67 solid obtained in step (1) in methanol solution to prepare ZIF-67 solution; then mix nickel nitrate solution with ZIF-67 solution to obtain auxiliary etching solution;
[0012] (3) Plasma etching: The auxiliary etching solution obtained in step (2) is placed in the reaction device and treated with plasma discharge to obtain the solution.
[0013] Beneficial effects: The preparation method provided by this invention is simple to operate, mild in conditions, highly efficient in reaction and low in cost, and has broad application prospects and value; the three-dimensional layered bimetallic hydroxide prepared has high active sites and excellent catalytic performance, which can effectively catalyze oxygen in the air and carry out a series of transformations to generate a large amount of ROS (reactive oxygen species), attacking and degrading antibiotics.
[0014] Preferably, in step (1), the mass ratio of 2-methylimidazole to cobalt nitrate hexahydrate is 1:1-3.
[0015] Preferably, the centrifugation speed in step (1) is 6000-10000 rpm and the centrifugation time is 5-10 min.
[0016] Preferably, the washing in step (1) specifically involves washing with methanol 2 to 4 times.
[0017] Preferably, the settling time in step (1) is 1 to 24 hours.
[0018] Preferably, the drying temperature in step (1) is -56 to 60°C.
[0019] Preferably, the concentration of the ZIF-67 solution in step (2) is 2 to 4 mg / mL.
[0020] Preferably, the concentration of the ZIF-67 solution in step (2) is 3 mg / mL.
[0021] Preferably, the concentration of the nickel nitrate solution in step (2) is 8-12 mg / mL.
[0022] Preferably, the concentration of the nickel nitrate solution in step (2) is 10 mg / mL.
[0023] Preferably, in step (2), the volume mixing ratio of nickel nitrate solution to ZIF-67 solution is 1-4:4-1.
[0024] Preferably, in step (3), the discharge power is 40-70W and the discharge processing time is 30-120s.
[0025] Preferably, the discharge atmosphere in step (3) is one of air, nitrogen, or oxygen.
[0026] A second aspect of the present invention provides a three-dimensional layered bimetallic hydroxide prepared by the above method.
[0027] A third aspect of the present invention proposes the application of the three-dimensional layered bimetallic hydroxide prepared by the above method in the degradation of antibiotics.
[0028] The advantages of this invention are:
[0029] 1. The preparation method provided by this invention is simple to operate, has mild conditions, high reaction efficiency and low cost, and has broad application prospects and value. The three-dimensional layered bimetallic hydroxide prepared has high active sites and excellent catalytic performance. It can effectively catalyze oxygen in the air and carry out a series of transformations to generate a large amount of ROS (reactive oxygen species), which attack and degrade antibiotics.
[0030] 2. The layered bimetallic hydroxide prepared using this invention retains its three-dimensional hollow structure, resulting in a significantly increased specific surface area. Furthermore, the obtained three-dimensional layered bimetallic hydroxide exhibits excellent catalytic activity when used as a nanoenzyme for the decomposition of antibiotics. Attached Figure Description
[0031] Figure 1 This is a schematic diagram of the dielectric barrier discharge plasma device in Embodiment 1 of the present invention, where 1-discharge device and 2-reaction device;
[0032] Figure 2 This is a SEM image of the ZIF-67 precursor in Embodiment 1 of the present invention;
[0033] Figure 3 The image shows the XRD pattern of the three-dimensional layered bimetallic hydroxide prepared in Example 1 of this invention.
[0034] Figure 4 This is a SEM image of the three-dimensional layered bimetallic hydroxide prepared in Example 1 of the present invention;
[0035] Figure 5 This diagram illustrates the catalytic mechanism of the three-dimensional layered bimetallic hydroxide in Example 1 of the present invention.
[0036] Figure 6 This is a graph showing the rate of air degradation of antibiotics catalyzed by three-dimensional layered bimetallic hydroxide in Example 1 of the present invention. Detailed Implementation
[0037] 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 in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0038] Example 1:
[0039] A method for preparing three-dimensional layered bimetallic hydroxides by plasma etching includes the following steps:
[0040] (1) Preparation of ZIF-67 precursor: First, 80 mg Co(NO3)2·6H2O was dissolved in methanol to form a pink solution; then, 40 mg 2-methylimidazole dissolved in 60 mL of methanol was poured into the above pink solution, and the solution quickly turned blue-purple; the mixed solution was shaken vigorously for 30 s and then allowed to stand at room temperature for 24 hours; after centrifugation at 8000 rpm for 7 min, the purple precipitate was collected, washed three times with methanol, and dried in an oven at 60 ℃ to obtain ZIF-67 solid;
[0041] (2) Preparation of auxiliary etching solution: Dissolve 50 mg Ni(NO3)2·6H2O in 5 mL of ultrapure water to prepare a 10 mg / mL nickel nitrate solution, and dissolve 15 mg ZIF-67 solid in 5 mL of ethanol solution to prepare a 3 mg / mL ZIF-67 solution; mix 1 mL of nickel nitrate solution and 4 mL of ZIF-67 solution to obtain the auxiliary etching solution;
[0042] (3) Plasma etching: The auxiliary etching solution obtained in step (2) is placed in the reaction device and subjected to plasma discharge for 60s in an air atmosphere. The discharge power is 50W. After the discharge is completed, the yellow-green product is collected, centrifuged at 8000rpm for 5 minutes, and washed three times with ultrapure water and ethanol to remove any possible free radicals and impurities.
[0043] Dielectric barrier discharge plasma device, such as Figure 1 As shown, specifically: the reaction device 2 is composed of plexiglass, with a diameter of 10cm and a height of 15cm. The positive and negative electrodes of the discharge device 1 are composed of stainless steel plates, with an electrode diameter of 35mm. The upper electrode is connected to a high-voltage, high-frequency AC power supply, and the lower electrode is grounded. When the voltage exceeds the threshold, the discharge plasma forms a gas-liquid solution interface in the gas, and then stabilizes by reducing the voltage.
[0044] Figure 2 The image shows a SEM image of the ZIF-67 precursor in this embodiment. As can be seen from the image, the ZIF-67 precursor has a smooth surface and uniform size, which conforms to the dodecahedral structure of ZIF-67.
[0045] The morphology and structure of the materials obtained above were characterized, and the results are as follows: Figure 3-4 As shown: The XRD results of the sample exhibit typical diffraction peaks at 2θ = 11°, 24°, 34°, and 61°, corresponding to the (0 03), (0 06), (00 9), and (1 1 0) planes, respectively. This indicates the presence of a typical LDH multilayer structure in the product, proving the successful preparation of the sample. Under air plasma-assisted etching conditions, the originally smooth ZIF-67 dodecahedral surface tends to become rough (e.g., Figure 4(as shown), but it still retains its three-dimensional polyhedral shape and structure.
[0046] In other words, the obtained cobalt-nickel layered bimetallic hydroxides inherited the shape and size of the ZIF-67 template, while their surfaces were covered by a large number of thick and interwoven ultrathin nanosheets. The samples exhibited a hollow structure with nanosheets as the shell; this unique hollow structure can significantly increase the specific surface area and provide numerous pores to enhance transport, facilitating the rapid diffusion of adsorbed substrates. These results demonstrate the potential applications of cobalt-nickel layered bimetallic hydroxides prepared by air plasma in the field of catalysis.
[0047] Antibiotic degradation experiment:
[0048] Because the prepared cobalt-nickel layered bimetallic hydroxide possesses multiple nanozyme activities, we cleverly designed an experiment to degrade antibiotics by pumping in air, utilizing its ability to convert oxygen into various ROS (reactive oxygen species) under certain conditions. The catalytic degradation of tetracycline was carried out under oxygen-introduced conditions.
[0049] Disperse 50-100 mg of the cobalt-nickel layered bimetallic hydroxide (Co-Ni LDH) prepared in this example into 10-50 mL of a 60 mg / mL tetracycline solution, and stir for 30-60 min under light-protected conditions to reach adsorption-desorption equilibrium. Then, use an air pump to pump air into the reaction system at a flow rate controlled at 0-1 L / min.
[0050] Because cobalt-nickel layered bimetallic hydroxides can first catalytically dissolve oxygen to obtain superoxide anions, which are then further converted into hydrogen peroxide and subsequently into hydroxyl radicals. Under certain conditions, hydrogen peroxide can also be decomposed into oxygen, which further participates in the catalytic cycle. Therefore, the degradation of antibiotics can be achieved by introducing gas.
[0051] The ROS (Reactive Oxygen Species) conversion mechanism and corresponding proof results are as follows: Figure 5 As shown in the figure, the cobalt-nickel layered bimetallic hydroxide prepared in this embodiment can rapidly oxidize hydrogen peroxide or oxygen to catalyze the substrate 3,3',5,5'-tetramethylbenzidine (TMB) to its oxidized form. This well illustrates the excellent catalytic ability of the cobalt-nickel layered bimetallic hydroxide.
[0052] Samples were taken every ten minutes and passed through a 0.22µm filter membrane to detect the UV-Vis of the filtrate. The degradation rate can be calculated using the following formula:
[0053] Degradation rate(%)=(A0-A) / A0*100%
[0054] Figure 6The degradation rates of antibiotics under different treatment conditions were shown. The results showed that, compared with the control groups, the degradation rate of antibiotics by cobalt-nickel layered bimetallic hydroxide under gas introduction conditions reached 99.6%.
[0055] Example 2:
[0056] A method for preparing three-dimensional layered bimetallic hydroxides by plasma etching includes the following steps:
[0057] (1) Preparation of ZIF-67 precursor: First, 40 mg of Co(NO3)2·6H2O was dissolved in methanol to form a pink solution; then, 40 mg of 2-methylimidazole dissolved in 60 mL of methanol was poured into the above pink solution, and the solution quickly turned blue-purple; the mixed solution was shaken vigorously for 30 s and then allowed to stand at room temperature for 1 hour; the purple precipitate was collected by centrifugation at 6000 rpm for 10 min, washed three times with methanol, and then freeze-dried at -56 °C to obtain ZIF-67 solid;
[0058] (2) Preparation of auxiliary etching solution: Dissolve 40 mg Ni(NO3)2·6H2O in 5 mL of ultrapure water to prepare an 8 mg / mL nickel nitrate solution, and dissolve 10 mg ZIF-67 solid in 5 mL of ethanol solution to prepare a 2 mg / mL ZIF-67 solution; mix 4 mL of nickel nitrate solution and 4 mL of ZIF-67 solution to obtain the auxiliary etching solution;
[0059] (3) Plasma etching: The auxiliary etching solution obtained in step (2) is placed in the reaction device and subjected to plasma discharge for 30s in an air atmosphere. The discharge power is 70W. After the discharge is completed, the yellow-green product is collected, centrifuged at 8000rpm for 5 minutes, and washed three times with ultrapure water and ethanol to remove any possible free radicals and impurities.
[0060] Example 3:
[0061] A method for preparing three-dimensional layered bimetallic hydroxides by plasma etching includes the following steps:
[0062] (1) Preparation of ZIF-67 precursor: First, 120 mg Co(NO3)2·6H2O was dissolved in methanol to form a pink solution; then, 40 mg 2-methylimidazole dissolved in 60 mL of methanol was poured into the above pink solution, and the solution quickly turned blue-purple; the mixed solution was shaken vigorously for 30 s and then allowed to stand at room temperature for 5 hours; the purple precipitate was collected by centrifugation at 10000 rpm for 5 min, washed three times with methanol, and dried at 30 °C to obtain ZIF-67 solid;
[0063] (2) Preparation of auxiliary etching solution: Dissolve 60 mg Ni(NO3)2·6H2O in 5 mL of ultrapure water to prepare a 12 mg / mL nickel nitrate solution, and dissolve 20 mg ZIF-67 solid in 5 mL of ethanol solution to prepare a 4 mg / mL ZIF-67 solution; mix 4 mL of nickel nitrate solution and 1 mL of ZIF-67 solution to obtain the auxiliary etching solution;
[0064] (3) Plasma etching: The auxiliary etching solution obtained in step (2) is placed in the reaction device and subjected to plasma discharge for 120s in an air atmosphere. The discharge power is 40W. After the discharge is completed, the yellow-green product is collected, centrifuged at 8000rpm for 5 minutes, and washed three times with ultrapure water and ethanol to remove any possible free radicals and impurities.
[0065] The morphology and structure of the materials prepared in Examples 2 and 3 are comparable to those in Example 1, and the degradation effect of the materials prepared in Examples 2 and 3 on antibiotics is comparable to that in Example 1.
[0066] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. The application of a three-dimensional layered bimetallic hydroxide in the degradation of antibiotics, characterized in that, Disperse 50-100 mg of the three-dimensional layered bimetallic hydroxide into 10-50 mL of a 60 mg / mL tetracycline solution and stir for 30-60 min under light-protected conditions to reach adsorption-desorption equilibrium. Next, an air pump is used to pump air into the reaction system, with the flow rate controlled to be greater than 0 and less than or equal to 1 L / min; the preparation method of the three-dimensional layered bimetallic hydroxide includes the following steps: (1) Preparation of ZIF-67 precursor: 2-methylimidazole and cobalt nitrate hexahydrate were dissolved in methanol solution, shaken and mixed, allowed to stand, centrifuged to collect the precipitate, washed and dried to obtain ZIF-67 solid; (2) Preparation of auxiliary etching solution: Dissolve the ZIF-67 solid obtained in step (1) in methanol solution to prepare ZIF-67 solution; The nickel nitrate solution is then mixed with the ZIF-67 solution to obtain the auxiliary etching solution; (3) Plasma etching: The auxiliary etching solution obtained in step (2) is placed in the reaction device and treated with plasma discharge to obtain the solution. The discharge conditions are air discharge, the discharge power is 40~70 W, and the discharge treatment time is 30~120 s.
2. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, In step (1), the mass ratio of 2-methylimidazole to cobalt nitrate hexahydrate is 1:1-3.
3. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, In step (1), the centrifugation speed is 6000~10000 rpm and the centrifugation time is 5~10 min.
4. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, In step (1), the washing process specifically involves washing with methanol 2 to 4 times; the standing time is 1 to 24 hours; and the drying temperature is -56 to 60°C.
5. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, The concentration of ZIF-67 solution in step (2) is 2~4 mg / mL.
6. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, The concentration of the nickel nitrate solution in step (2) is 8~12 mg / mL.
7. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, In step (2), the volume mixing ratio of nickel nitrate solution to ZIF-67 solution is 1~4:4~1.
8. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, The discharge conditions in step (3) are air discharge, discharge power of 50 W, and discharge processing time of 60 s.
9. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, The discharge conditions in step (3) are air discharge, the discharge power is 70 W, and the discharge processing time is 30 s.
10. The application of the three-dimensional layered bimetallic hydroxide according to claim 1 in the degradation of antibiotics, characterized in that, The discharge conditions in step (3) are air discharge, the discharge power is 40 W, and the discharge processing time is 120 s.