A method for preparing and applying a CoNiFe-MOF / LDH catalyst for an electro-Fenton system.

Abstract

This invention discloses a method for preparing a CoNiFe-MOF / LDH catalyst for an electro-Fenton system. The method involves dissolving cobalt chloride, nickel chloride, ferrous chloride, and urea and performing a hydrothermal reaction to obtain a CoNiFe-LDH precursor template. This CoNiFe-LDH precursor template is then reacted with the organic ligand 2,3,6,7,10,11-hexahydroxytriphenylene to prepare the CoNiFe-MOF / LDH catalyst. This invention also discloses the application of the CoNiFe-MOF / LDH material as a heterogeneous electro-Fenton catalyst in the degradation of organic wastewater. The catalyst of this invention is a rod-shaped porous nanostructure synthesized via a hydrothermal method, exhibiting excellent electrocatalytic performance. It can efficiently remove antibiotics from the aquatic environment with a high degree of mineralization. A removal rate of 97% can be achieved within 60 minutes, and the mineralization rate remains above 80% within 420 minutes.

Description

Technical Field

[0001] This invention relates to the fields of materials and environment. Specifically, this invention relates to a CoNiFe-MOF / LDH catalyst for an electro-Fenton system and its preparation method, as well as the application of the catalyst in the degradation of antibiotics in wastewater. Background Technology

[0002] Antibiotics are essential drugs for treating various bacterial infections and are widely used in human health, animal husbandry, and agriculture. However, the overuse of antibiotics has led to an increasing amount of antibiotics being discharged into water bodies, posing a considerable risk to human health and ecological balance. Sulfonamides, with their broad antibacterial activity, high efficacy, and low cost, are widely used and are also a common type of pollutant in water environments. Current strategies for treating antibiotic wastewater include biological methods, physical methods, and advanced oxidation processes (AOPs). Among these, AOPs can trigger the efficient generation of reactive oxygen species through light radiation, electrochemical reactions, and catalyst activation, providing a rapid solution for pollutant degradation and effectively degrading antibiotics into harmless carbon dioxide and water. However, many AOPs face numerous obstacles when treating antibiotic-containing water. For example, traditional homogeneous Fenton and Fenton-like processes require harsh acidic conditions or the addition of extra reagents and produce iron-containing sludge. The intermediate products from the degradation of antibiotics by peroxymonosulfate activated oxidation are highly toxic. Ultraviolet (UV)-Fenton, Fenton / TiO2, and UV-Fenton / TiO2 also suffer from low energy efficiency, high cost, and low mineralization rates. Among all AOPs, electrochemical advanced oxidation technologies are receiving increasing attention due to their advantages such as zero reagents, high degradation efficiency of recalcitrant pollutants, good controllability, and low secondary pollution.

[0003] Electro-Fenton (EF) reaction, as an emerging electrochemical advanced oxidation technology, is based on a two-electron redox reaction to generate hydrogen peroxide (H2O2). H2O2 can react with a catalyst to generate a powerful hydroxyl radical (·OH)(E 0 (·OH / H2O)=2.80V), which can efficiently remove recalcitrant organic pollutants, and has the advantages of fast reaction speed, low toxicity, and good environmental compatibility. Since the optimal pH value for the homogeneous EF process is 2.8–3.5, it is not suitable for pH-neutral urban wastewater treatment; and the active substances (Fe) in the system... 2+ The inability to recycle Fe, the generation of iron sludge, and the increased processing costs significantly limit its application. Replacing Fe with a solid-phase catalyst... 2+The heterogeneous electro-Fenton (Hetero-EF) system can effectively overcome the problems of traditional homogeneous EF. It boasts advantages such as environmental compatibility, superior efficiency, strong adaptability, and higher degradation efficiency for organic pollutants in wastewater. The Hetero-EF process also offers advantages such as wide pH adaptability, good reusability, and environmental friendliness, while reducing costs. Therefore, considering the future demand for efficient water treatment technologies, finding a highly efficient and stable catalyst is a crucial step for the Hetero-EF system.

[0004] Layered double hydroxides (LDHs) are novel two-dimensional transition metal nanomaterials composed of metal hydroxides, interlayer compensating anions, and interlayer water. Due to their compositional and structural flexibility and the abundance of transition metal ions, LDHs have proven to be excellent Fenton catalysts. However, the electrocatalytic performance of LDHs is limited by their small specific surface area, low conductivity, and tendency to aggregate. Current research focuses on overcoming these limitations by incorporating materials with good conductivity or large specific surface area into LDHs to improve their performance, such as various metals, carbon nanomaterials, and magnetic materials. Metal-organic frameworks (MOFs) use metal ions as connection points and organic ligands as supports to form a space. They possess advantages such as high porosity, low density, large specific surface area, tunable pore size, and diverse structures, and have been used in the Hetero-EF system for removing antibiotics from aquatic environments. However, traditional MOFs suffer from poor water stability. Therefore, it is necessary to develop an electrocatalyst that can exist stably in the aquatic environment and has good catalytic performance in order to better remove antibiotics from wastewater. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide a CoNiFe-MOF / LDH catalyst for electro-Fenton systems. A hydrothermal synthesis method is employed, using CoNiFe-LDH as a template to coordinate with a 2,3,6,7,10,11-hexahydroxytriphenylene organic ligand to form a nanorod-shaped MOF catalyst. Antibiotics, widely present in aquatic environments, are used as a pollutant model for degradation and removal via a heterogeneous electro-Fenton process, thereby improving the degradation rate of antibiotics in wastewater.

[0006] To achieve the above objectives, the present invention first provides a CoNiFe-MOF / LDH catalyst for an electro-Fenton system, comprising the following steps:

[0007] (1) Dissolve cobalt chloride, nickel chloride, ferrous chloride and urea in ultrapure water, sonicate to mix them thoroughly, and then transfer them to a polytetrafluoroethylene-lined steel high-pressure reactor for hydrothermal reaction.

[0008] (2) After the hydrothermal reaction in step (1) was naturally cooled, the solution was washed by centrifugation and vacuum dried to obtain the precursor template of CoNiFe-LDH.

[0009] (3) The CoNiFe-LDH precursor template obtained in step (2) was immersed in an N,N-dimethylformamide solution containing 2,3,6,7,10,11-hexahydroxytriphenylbenzene. After ultrasonic dispersion, the solution was sealed in a high-pressure reactor with a polytetrafluoroethylene liner for solvothermal reaction.

[0010] (4) After the solution after the solvothermal reaction in step (3) is naturally cooled, it is washed by centrifugation and dried under vacuum to obtain the CoNiFe-MOF / LDH catalyst.

[0011] In one embodiment of the present invention, the molar ratio of cobalt chloride, nickel chloride, ferrous chloride and urea in step (1) is (1.1-1.3):(0.24-0.26):(0.14-0.16):(6-6.5).

[0012] In one embodiment of the present invention, in step (1), the ultrasonic power is 40W and the ultrasonic time is 0.5-1h.

[0013] In one embodiment of the present invention, the hydrothermal reaction temperature in step (1) is 120-150°C and the time is 12-15h.

[0014] In one embodiment of the present invention, the vacuum drying temperature in step (2) is 80-100°C and the time is 12-24h.

[0015] In one embodiment of the present invention, the mass ratio of the CoNiFe-LDH template to the organic ligand 2,3,6,7,10,11-hexahydroxytriphenylbenzene in step (3) is (0.9-1.2):(1.8-2.1).

[0016] In one embodiment of the present invention, in step (3), the concentration of 2,3,6,7,10,11-hexahydroxytriphenylbenzene in the N,N-dimethylformamide solution containing 2,3,6,7,10,11-hexahydroxytriphenylbenzene is 10-12 mg / mL.

[0017] In one embodiment of the present invention, in step (3), the power of ultrasonic dispersion is 40W and the ultrasonic time is 0.5-1h.

[0018] In one embodiment of the present invention, the solvothermal reaction temperature in step (3) is 100-120°C and the time is 24-28h.

[0019] In one embodiment of the present invention, the vacuum drying temperature in step (4) is 80-100°C and the time is 12-24h.

[0020] The present invention also provides a CoNiFe-MOF / LDH catalyst prepared according to the above method.

[0021] The present invention also provides an application of the above-mentioned catalyst in the degradation of wastewater.

[0022] In one embodiment of the present invention, the application includes degrading at least one of sulfadiazine, sulfamethoxazole, sulfisoxazole, sulfamethylpyrimidine, sulfadiazine, sulfapyridine, sulfamethoxypyrimidine, and sulfathiazole in wastewater.

[0023] In one embodiment of the present invention, the method for degrading sulfadiazine in wastewater includes the following steps: using carbon paper as the cathode and platinum sheet as the anode, placing the cathode and anode in parallel in an electrolytic cell, adding a mixed solution of electrolyte and wastewater to the electrolytic cell, connecting the other end of the cathode and anode to the corresponding electrodes of a DC power supply, continuously introducing oxygen into the solution, adding a CoNiFe-MOF / LDH catalyst and continuously stirring.

[0024] In one embodiment of the present invention, the electrolyte includes at least one of Na2SO4, NaCl, and K2SO4, the concentration of the electrolyte solution is 0.05 to 0.1 mol / L, and the pH of the electrolyte solution is 2.0 to 9.0.

[0025] In one embodiment of the present invention, the output current of the power supply is 5.0 to 35.0 mA, the electrode spacing between the positive and negative electrodes is 2.0 cm, and the oxygen flow rate is 0.5 to 1.0 L / min.

[0026] In one embodiment of the present invention, the amount of the CoNiFe-MOF / LDH catalyst used is 0.08 to 0.2 g / L of mixed solution.

[0027] The principle of the electro-Fenton degradation method for sulfadiazine in aqueous solution in this invention is as follows: Under constant current output, the introduced oxygen undergoes in-situ electro-generation of H2O2 through two-electron transfer at the cathode. Then, the H2O2 reacts with the metal active sites on the catalyst surface to activate and generate hydroxyl radicals (·OH) and superoxide radicals (·O2). - ) and singlet oxygen ( 1Active oxygen (O2) effectively promotes the degradation and mineralization of pollutants. The oxidized metal ions can undergo reduction reactions at the cathode, enabling the recycling of metal ions and improving degradation efficiency.

[0028] Advantages and effects of the present invention:

[0029] (1) This invention successfully prepared a nanorod-shaped MOF catalyst by using a hydrothermal synthesis method, with CoNiFe-LDH as a template, and coordinating with 2,3,6,7,10,11-hexahydroxytriphenylbenzene organic ligand.

[0030] (2) The specific surface area of ​​the CoNiFe-MOF / LDH catalyst prepared by the method of the present invention is 32.26 m². 2 g -1 It has an ordered mesoporous structure and exhibits good catalytic performance.

[0031] (3) This invention uses a heterogeneous electro-Fenton method with CoNiFe-MOF / LDH as a catalyst to degrade and remove sulfadiazine, a common antibiotic in the aquatic environment. The CoNiFe-MOF / LDH catalyst shows high degradation efficiency for sulfadiazine, with a removal rate of 98% in 60 min and a TOC% of 85.66% in 420 min. Moreover, the removal rate is still above 90% after more than 5 cycles of recycling. It has good degradation and mineralization capabilities and reusability. In addition, it also shows good and efficient degradation capabilities for several common sulfonamide antibiotics in the aquatic environment. This method is simple to operate, green and safe, and has great potential for application in complex water pollution. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the apparatus for degrading wastewater using the electro-Fenton method in this invention;

[0033] Figure 2 This is a synthetic route diagram of the CoNiFe-MOF / LDH catalyst in this invention;

[0034] Figure 3 The images show scanning electron microscope (SEM) images of the materials CoNiFe-MOF / LDH and CoNiFe-LDH prepared in Example 1 and Comparative Example 1 of this invention, where (a) is the material CoNiFe-MOF / LDH and (b) is the material CoNiFe-LDH.

[0035] Figure 4 The X-ray diffraction patterns of CoNiFe-MOF / LDH and CoNiFe-LDH prepared in Example 1 and Comparative Example 1 of this invention are shown below.

[0036] Figure 5Fourier transform infrared spectra of the materials CoNiFe-MOF / LDH and CoNiFe-LDH prepared in Example 1 and Comparative Example 1 of this invention;

[0037] Figure 6 The N2 adsorption-desorption isotherms of CoNiFe-MOF / LDH and CoNiFe-LDH prepared in Example 1 and Comparative Example 1 of this invention are shown below.

[0038] Figure 7 The following are the removal effect diagrams of sulfadiazine in different systems in Example 2 of the present invention. EO represents the removal effect diagram when only current is applied and no catalyst is added, CoNiFe-MOF / LDH-Adsorption represents the removal effect diagram when only catalyst is added and no current is applied, and CoNiFe-MOF / LDH-HEF represents the removal effect diagram when both catalyst and current are applied.

[0039] Figure 8 The removal effect of sulfadiazine under different current conditions in Example 3 of the present invention;

[0040] Figure 9 The effect of different catalyst dosages on the removal of sulfadiazine in Example 4 of the present invention;

[0041] Figure 10 The effect of different initial pH conditions on the removal of sulfadiazine in Example 5 of the present invention;

[0042] Figure 11 This is a diagram illustrating the removal effect of different types of antibiotics in Example 6 of the present invention.

[0043] Figure 12 The image shows the removal effect of sulfadiazine in different actual water samples in Example 7 of this invention.

[0044] Figure 13 The graphs show the degradation and removal effects of CoNiFe-LDH on sulfadiazine in different systems in Comparative Example 2 of this invention. EO represents the removal effect when only current is applied and no catalyst is added, CoNiFe-LDH-Adsorption represents the removal effect when only catalyst is added and no current is applied, and CoNiFe-LDH-HEF represents the removal effect when both catalyst and current are applied.

[0045] Figure 14 The images show the degradation and removal effects of sulfadiazine by the materials in Example 2, Comparative Example 2, and Comparative Example 3. Detailed Implementation

[0046] The present invention will be further illustrated by the following examples, but the implementation of the present invention is not limited thereto.

[0047] Example 1

[0048] Synthesis of CoNiFe-MOF / LDH catalyst

[0049] (1) Cobalt chloride hexahydrate (300 mg), nickel chloride hexahydrate (60 mg), ferrous chloride tetrahydrate (30 mg) and urea (380 mg) were mixed in deionized water. The solution was sonicated at 40 W for 1 h, heated at 120 °C for 12 h, cooled to room temperature, washed several times with deionized water, and the CoNiFe-LDH template was collected and dried at 90 °C for 12 h.

[0050] (2) The CoNiFe-LDH template obtained in step (1) was immersed in 20 mL of N,N-dimethylformamide solution containing 2,3,6,7,10,11-hexahydroxytriphenylene to obtain a mixture, wherein the mass ratio of CoNiFe-LDH template to 2,3,6,7,10,11-hexahydroxytriphenylene in the mixture was 1:2; the mixture was ultrasonically dispersed at 40 W for 60 minutes to ensure homogeneity. The dispersed solution was sealed in a polytetrafluoroethylene-lined autoclave and subjected to a solvothermal reaction at 100 °C for 24 hours. After natural cooling to room temperature, the final black solid product was collected by centrifugation, thoroughly washed with ultrapure water, N,N-dimethylformamide and ethanol, and dried in a vacuum drying oven at 90 °C for 12 h to obtain the CoNiFe-MOF / LDH catalyst.

[0051] Comparative Example 1

[0052] The difference between Comparative Example 1 and Example 1 is that step (2) is omitted.

[0053] The morphology and structure of the CoNiFe-MOF / LDH synthesized in Example 1 and the CoNiFe-LDH synthesized in Comparative Example 1 were characterized by SEM, as well as by comparing their morphology and structure. Figure 3 As shown in b, the CoNiFe-LDH template exhibits a regular, smooth nanowire structure that aggregates together. By using CoNiFe-LDH as a template to achieve coordination chemistry with organic ligands, the regular, smooth CoNiFe-LDH nanowires transform into a dense, fine rod-like structure as the MOF structure grows through grafting. Figure 3 a) This allows for the complete embedding of MOF into the CoNiFe-LDH topology, thus achieving the successful preparation of the CoNiFe-MOF / LDH catalyst.

[0054] The crystal structure of CoNiFe-MOF / LDH was further investigated using XRD, such as... Figure 4As shown, the diffraction peaks of CoNiFe-MOF / LDH at 10.02°, 17.19° and 19.97° are observed. After CoNiFe-LDH is coordinated with the organic ligand, a characteristic peak corresponding to the organic ligand appears at 27.04°, indicating the successful synthesis of CoNiFe-MOF / LDH.

[0055] The functional groups and other properties of the synthesized CoNiFe-MOF / LDH were investigated using FT-IR, such as... Figure 5 As shown; the spectrum is displayed at 1375 cm⁻¹. -1 The nearby spectral band is related to the stretching vibration of C=O in carbonates. It is located at 3514 cm⁻¹. -1 The broad absorption at 746 cm⁻¹ is attributed to the stretching of OH groups in the interlayer water molecules; and 746 cm⁻¹ -1 The absorption peak at this point can be attributed to the CH bending vibration. The spectrum is approximately 688 cm⁻¹. -1 Approximately 510cm -1 The absorption peaks at 1258 cm⁻¹ are attributed to the vibrations of the M-OH and MOM bonds, respectively. Compared to the spectrum of CoNiFe-LDH materials, the peak at 1258 cm⁻¹ is [not specified]. -1 1654cm -1 The peak at this location is attributed to the CO stretching vibration of the organic ligand backbone and the C-C stretching vibration of the aromatic backbone. This further confirms the successful preparation of the material.

[0056] The specific surface area and pore size of the CoNiFe-MOF / LDH synthesized in Example 1 and the CoNiFe-LDH synthesized in Comparative Example 1 were analyzed using N2 adsorption-desorption isotherms. Figure 6 As shown, CoNiFe-MOF / LDH follows a type IV isotherm, and its BET specific surface area is 32.26 m². 2 g -1 It exhibits ordered mesopores. CoNiFe-LDH follows a type II isotherm, reflecting typical physisorption processes on non-porous or macroporous adsorbents, and has a BET specific surface area of ​​13.96 m². 2 g -1 This indicates that the CoNiFe-MOF / LDH formed by hybridization of CoNiFe-LDH and MOF structures exhibits porosity, which is beneficial for improving catalytic performance.

[0057] Example 2

[0058] Application of CoNiFe-MOF / LDH in heterogeneous Fenton systems

[0059] In the Hetero-EF system, the electrogeneration of H2O2 and the degradation of organic pollutants are carried out in a semi-closed electrolytic cell containing 150 mL of electrolyte solution at pH 3. This electrolyte solution contains 0.05 mol / L Na2SO4 and 10 mg / L sulfadiazine (SMT). The electrolytic cell is at room temperature and operated under vigorous magnetic stirring at 700 rpm. The cathode and anode are mounted parallel to each other in the electrolytic cell, 2 cm apart. The anode is a platinum electrode (1 cm x 2 cm), and the cathode is a GDS-CP (2 cm x 2.5 cm). Figure 1 As shown. During this process, oxygen was introduced into the O2 generator at a flow rate of 0.8 L / min, with continuous stirring during the oxygen introduction. After a brief adsorption period following the addition of the catalyst, a constant current of 25 mA was supplied by a DC power supply to begin the Hetero-EF removal process, which lasted for 60 min. After the catalyst was added, the concentration of the catalyst in the electrolytic cell was 0.16 g / L.

[0060] SMT concentration was detected by high-performance liquid chromatography (HPLC), and the degradation rate was calculated. The concentration ratio before and after degradation (Ct / C0) was selected as the standard for evaluating the degradation effect; a smaller Ct / C0 ratio indicates a better degradation effect. Figure 7 As can be seen, when 0.16 g / L CoNiFe-MOF / LDH is present as a catalyst for Hetero-EF in a 10 mg / L SMT drug solution, the degradation rate of SMT can reach as high as 98% within one hour under the application of a current of 25 mA.

[0061] Example 3: Effect of Current on Degradation Efficiency

[0062] The difference between Example 3 and Example 2 is that the current provided by the DC power supply is changed to 5, 15, 25 and 35mA respectively, and Ct / C0 is calculated.

[0063] like Figure 8 As shown, the Ct / CO ratio decreases with increasing current, resulting in a higher degradation rate. When the current exceeds 25 mA, the degradation rate begins to decline. This is due to side reactions caused by high current, such as the 4e-ORR pathway and hydrogen evolution reaction, which decrease the hydrogen peroxide yield and correspondingly weaken the generation of hydroxyl radicals, leading to a decrease in degradation rate. Therefore, a current of 25.0 mA yields the optimal removal rate for SMT.

[0064] Example 4: Effect of catalyst addition amount on degradation effect

[0065] The difference between Example 4 and Example 2 is that the amount of catalyst added is changed so that the concentration of catalyst in the electrolytic cell is 0.08, 0.12, 0.16 and 0.2 g / L, respectively, and Ct / C0 is calculated.

[0066] like Figure 9 As shown, the degradation rate increases with increasing catalyst concentration from 0.08 g / L to 0.16 g / L. The number of active sites also increases with increasing catalyst concentration, leading to a higher degradation rate. However, further increasing the catalyst concentration (0.2 g / L) does not significantly improve the degradation rate.

[0067] Example 5: Effect of Catalyst Addition Amount on Degradation Efficiency

[0068] The difference between Example 5 and Example 2 is that the pH of the electrolyte solution was changed so that the pH of the electrolyte solution in the electrolytic cell was 2, 3, 4, 5, 6, 7, 8, and 9, and Ct / C0 was calculated.

[0069] like Figure 10 As shown, the degradation effect decreases with increasing pH from 2 to 9, and the degradation effect is best at pH=3.

[0070] Example 6

[0071] Application of CoNiFe-MOF / LDH in the Degradation of Different Antibiotics in a Heterogeneous Electro-Fenton System

[0072] The difference between Example 6 and Example 2 is that 10 mg / L of sulfamethoxazole, sulfaisoxazole, sulfamethazine, sulfadiazine, sulfapyridine, sulfadiazine, sulfamethoxypyrimidine, and sulfathiazole were used instead of 10 mg / L of SMT as the target contaminant in Example 2.

[0073] like Figure 11 As shown, the CoNiFe-MOF / LDH material, as a catalyst in the Hetero-EF system, exhibits excellent degradation efficiency for sulfonamide organic pollutants. The Hetero-EF reaction almost completely removes sulfathiazole and sulfaisoxazole, while the removal rates for sulfamethoxazole (97.19%), sulfamethylpyrimidine (96.92%), sulfadiazine (89.27%), sulfapyridine (98.00%), sulfamethoxypyrimidine (93.95%), and SMT (98.41%) are all above 89%. Therefore, this catalyst has good versatility in degrading various pollutants.

[0074] Example 7: Application of CoNiFe-MOF / LDH in Heterogeneous Electro-Fenton System in Real Water Samples

[0075] The difference between Example 7 and Example 2 is that the wastewater samples were taken from lake water and tap water from Jiangnan University and Lihu Lake in Wuxi City, Jiangsu Province, respectively. The collected water samples were stored in a refrigerator at 4°C. During the experiment, the water samples were first filtered through a 0.22 μm aqueous phase filter membrane to remove impurities. Then, the filtered water samples were used as solvents to prepare an electrolyte solution containing 0.05 mol / L Na2SO4 and 10 mg / L SMT. The pH of the solution was adjusted to 3 and applied to the removal of SMT in a heterogeneous electro-Fenton system.

[0076] like Figure 12 As shown, tap water and lake water from different locations were used as solvents. Firstly, sulfadimidine was not detected in the solvents. Then, a spiked removal experiment was conducted with a sulfadimidine concentration of 10 mg / L. The results indicate that the substances in the actual water samples had little impact on the removal of SMT, and the degradation rates all exceeded 97%. This demonstrates the significant importance and feasibility of this method for antibiotic removal research in real-world aquatic environments.

[0077] Comparative Example 2: Application of CoNiFe-LDH as a catalyst for the degradation of sulfadiazine

[0078] The difference between Comparative Example 2 and Example 2 is that the catalyst used was prepared in the same way as in Comparative Example 1.

[0079] 0.16 g / L CoNiFe-LDH was selected as the suspended particulate catalyst, such as... Figure 13 As shown, the adsorption removal rate of SMT was 0.1%, and the degradation rate of the Hetero-EF process catalyzed by CoNiFe-LDH was 88.53% at 60 minutes, which was lower than that of the CoNiFe-MOF / LDH catalyst, indicating that the CoNiFe-MOF / LDH catalyst has higher electrocatalytic performance and more active sites.

[0080] Comparative Example 3

[0081] The difference between Comparative Example 3 and Example 2 is that the catalyst used is prepared in a different way. In Comparative Example 3, 2,6-naphthalenedicarboxylic acid dipotassium salt is used as the ligand to replace 2,3,6,7,10,11-hexahydroxytriphenylene.

[0082] A 0.16 g / L LDH / MOF (with dipotassium 2,6-naphthalenedicarboxylate as the ligand) was selected as the heterogeneous catalyst, such as... Figure 14 As shown, the degradation rate of SMT was 87.88% after 60 minutes. The degradation effect was almost the same as that of the CoNiFe-LDH catalyst, indicating that the catalytic performance of the LDH / MOF catalyst synthesized with dipotassium 2,6-naphthalenedicarboxylate as a ligand was not improved.

[0083] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. Use of CoNiFe-MOF / LDH catalyst in degrading wastewater, characterized in that, The application comprises degrading antibiotics in wastewater by taking CoNiFe-MOF / LDH as a catalyst, wherein the preparation method of the CoNiFe-MOF / LDH catalyst comprises the following steps: (1) Dissolve cobalt chloride, nickel chloride, ferrous chloride and urea in ultrapure water, and ultrasonically mix them until they are fully dissolved, then transfer the mixture to a polytetrafluoroethylene-lined steel high-pressure reaction kettle for hydrothermal reaction; the molar ratio of cobalt chloride, nickel chloride, ferrous chloride and urea in step (1) is (1.1-1.3):(0.24-0.26):(0.14-0.16):(6-6.5); (2) After the solution obtained in step (1) is naturally cooled, it is centrifuged and washed clean, and then vacuum dried to obtain a CoNiFe-LDH precursor template; (3) The CoNiFe-LDH precursor template obtained in step (2) is immersed in an N,N-dimethylformamide solution containing 2,3,6,7,10,11-hexahydroxytriphenylbenzene, and after ultrasonic dispersion, the solution is sealed in a polytetrafluoroethylene-lined high-pressure kettle for solvothermal reaction; the mass ratio of the CoNiFe-LDH template to the organic ligand 2,3,6,7,10,11-hexahydroxytriphenylbenzene in step (3) is (0.9-1.2):(1.8-2.1), the concentration of 2,3,6,7,10,11-hexahydroxytriphenylbenzene in the N,N-dimethylformamide solution containing 2,3,6,7,10,11-hexahydroxytriphenylbenzene is 10-12 mg / mL, and the solvothermal reaction temperature is 100-120°C and the time is 24-28 h; (4) After the solution obtained in step (3) is naturally cooled, it is centrifuged and washed clean, and then vacuum dried to obtain a CoNiFe-MOF / LDH catalyst.

2. Use according to claim 1, characterized in that, In step (1), the ultrasonic power is 40 W, the ultrasonic time is 0.5-1 h, the hydrothermal reaction temperature is 120-150°C, and the time is 12-15 h.

3. Use according to claim 1, characterized in that, The antibiotics include at least one of sulfadimidine, sulfisoxazole, sulfisomidine, sulfadiazine, sulfapyridine, sulfisomidine, sulfathalidine, and sulfathiazole.

4. Use according to claim 1, characterized in that, The method for degrading antibiotics in wastewater comprises the following steps: taking carbon paper as a cathode and platinum sheet as an anode, placing the cathode and anode parallelly in an electrolytic cell, adding a mixed solution of an electrolyte and wastewater into the electrolytic cell, connecting the other end of the cathode and anode to the corresponding electrodes of a direct current power supply, continuously introducing oxygen into the solution, adding a CoNiFe-MOF / LDH catalyst and continuously stirring.

5. Use according to claim 4, characterized in that, The electrolyte comprises at least one of Na2SO4, NaCl, and K2SO4, the concentration of the electrolyte in the mixed solution is 0.05-0.1 mol / L, and the pH of the electrolyte solution is 2.0-9.

0.

6. Use according to claim 4, characterized in that, The output current of the power supply is 5.0-35.0 mA, the electrode spacing of the cathode and the anode is 2.0 cm, the oxygen flow rate is 0.5-1.0 L / min, and the amount of the CoNiFe-MOF / LDH catalyst is 0.08-0.2 g / L of the mixed solution.

7. The CoNiFe-MOF / LDH catalyst prepared according to the preparation method of the CoNiFe-MOF / LDH catalyst in claim 1 or 2.

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