Ce-mof derivative materials, electrodes comprising the materials, and methods of making and using the same

Abstract

The application relates to the technical field of wastewater treatment, in particular to a Ce-MOF derivative material, an electrode containing the material, and a preparation method and application thereof, wherein the Ce-MOF derivative material is obtained by calcining a Ce-MOF at 450-750 DEG C; the Ce-MOF derivative material is coated on an electrode base material to obtain a Ce-MOF derivative electrode material, and the material is applied to degradation treatment of antibiotic wastewater. The prepared Ce-MOF derivative material effectively overcomes the shortcomings of poor conductivity of a traditional metal organic framework material Ce-MOF and limited degradation efficiency of a Fenton-like reaction, the preparation process is simple, and in the process of applying the material to an electro-Fenton degradation reaction of quinolone antibiotics, a strong oxidizing SO4 − Can be quickly generated in a reaction system, so that the degradation effect of LFX is obviously improved, the electrode material is easy to recycle and reuse, and the antibiotic wastewater is not secondarily polluted, so the material has a wide application prospect in the field of antibiotic wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to Ce-MOF derivative materials, electrodes containing such materials, their preparation methods, and applications. Background Technology

[0002] Antibiotics are common in daily life and can effectively help humans cure diseases. They first came to public attention in the late 1920s and are now available in a wide variety of types. In recent years, antibiotics have been widely used in hospitals and play an increasingly important role in clinical medicine. However, antibiotics have also brought environmental harm. Most antibiotics taken by humans and animals are not fully absorbed and end up in sewage or directly discharged into the aquatic environment, exacerbating water pollution. Levofloxacin, a quinolone antibiotic, is widely used in medicine, aquaculture, and animal husbandry, but only about 20% is utilized by the body; the rest enters the environment through various pathways. In recent years, levofloxacin has been detected in surface water, groundwater, and drinking water. Its entry into water bodies can cause serious environmental problems and pose a potential threat to public health. Due to its non-biodegradable nature, traditional wastewater treatment technologies are insufficient to effectively remove it. Currently, existing methods for treating antibiotic wastewater can be summarized as follows: physicochemical treatment methods, aerobic biological treatment methods, anaerobic biological treatment methods, and combinations of multiple methods.

[0003] Among existing physicochemical methods for antibiotic degradation, electrocatalysis has emerged as a novel wastewater treatment technology due to its low cost and good environmental compatibility. However, the efficiency of electrochemical processes alone is relatively low, and the degradation effect can generally only be improved by increasing the current density or extending the reaction time, which significantly increases the cost. Currently, there are reports of using metal oxides such as iron, cobalt, and nickel to activate sodium persulfate for antibiotic degradation. However, since most of these methods involve loading metal oxides onto nickel foam as electrode materials, and nickel foam is easily oxidized and corroded, the metal oxides tend to detach during the electrocatalytic oxidation degradation reaction. This detachment of metal oxides can easily cause secondary pollution of water bodies, and the catalyst is difficult to recover. If only carbon materials are used as electrodes for the electrochemical activation and degradation of antibiotic wastewater, the degradation rate is often low, resulting in low current efficiency.

[0004] Patent application CN202110298110.0 reports a NiO / Co3O4-NF composite cathode used for electro-Fenton degradation of levofloxacin antibiotics, achieving a degradation rate of over 77.8% in 2 hours under optimal conditions. However, because the nickel foam carrier is easily oxidized and corroded in wastewater treatment, the detached catalyst after degradation can easily cause secondary pollution to the water body. Patent application CN201711331990.7 reports an insoluble magnetic cobalt / defective g-C3N4 composite catalyst and its application in catalytic degradation of levofloxacin in wastewater, achieving a degradation rate of 77% for 10 mg / L levofloxacin within 1 hour, but still requiring magnetic recovery of the catalyst from the wastewater. The paper "Iron Oxide Activated Persulfate Degradation of Antibiotic Pollutants" (Li Tongyan. Iron Oxide Activated Persulfate Degradation of Antibiotic Pollutants [D]. Hebei Normal University, 2020.) mentions that the stability of iron oxides is 43% after three cycles, and the recyclability needs to be improved. There is still a problem of iron ion leaching. Since iron oxide is in powder form and dispersed in water, it is difficult to collect and reuse. Summary of the Invention

[0005] This invention aims to overcome the problems and shortcomings of existing technologies in the electrocatalytic oxidation degradation of quinolone antibiotics, and provides a method for preparing Ce-MOF derivative materials, which are then used as electrode materials to activate persulfate to degrade quinolone antibiotics. This overcomes the problems of poor degradation effect, difficulty in recovering the catalyst loaded on the electrode material, low recyclability, and secondary pollution of water bodies that exist in existing technologies.

[0006] To achieve the above-mentioned objectives, the present invention is implemented through the following technical solution:

[0007] The first objective of this invention is to provide a method for preparing Ce-MOF derivative materials, comprising the following steps:

[0008] (1) Disperse cerium nitrate hexahydrate in N,N-dimethylformamide to obtain solution A;

[0009] (2) Disperse 1,3,5-benzenetricarboxylic acid in N,N-dimethylformamide to obtain solution B;

[0010] (3) Mix the above solutions A and B evenly, and then put them into a reaction vessel for hydrothermal reaction. After the reaction is completed, cool to room temperature to obtain the reaction solution;

[0011] (4) Centrifuge the above reaction solution, wash the obtained product and dry it to obtain Ce-MOF;

[0012] (5) Ce-MOF was calcined at 450~750℃ to obtain Ce-MOF derivatives.

[0013] Metal-organic coordination polymers (MOFs) are a novel class of flexible microporous materials that have attracted widespread attention due to their diverse topologies, controllable pores, high specific surface area, and unique optical, electrical, and magnetic properties. Ce-MOFs are a general term for Ce-based metal-organic framework materials, and very few Ce-MOFs have been developed to date. In this study, Ce-MOFs with excellent porosity and high specific surface area were prepared by hydrothermal method. By combining calcination treatment and adjusting the calcination temperature (450–750 °C), Ce-MOF derivatives with stronger oxygen adsorption capacity, better conductivity, more active sites, and larger specific surface area compared to the original Ce-MOFs were obtained.

[0014] Preferably, in step (3), the molar ratio of cerium nitrate hexahydrate to 1,3,5-benzenetricarboxylic acid in the mixture of A and B is 1:0.5 to 2.

[0015] Preferably, the hydrothermal reaction temperature in step (3) is 100~130℃ and the time is 20~30h.

[0016] The main process for preparing Ce-MOF derivatives in this invention is as follows: Ce(NO3)3·6H2O and C9H6O6 in a molar ratio of 1:0.5–2 are dissolved in 30 mL of N,N-dimethylformamide (DMF) solution, and stirred for 10–30 minutes until completely dissolved. The two solutions are then mixed and stirred for 30–60 minutes until homogeneous. The mixture is then transferred to a PTFE hydrothermal reactor and placed in an oven at 100–130 °C for 20–30 hours for hydrothermal reaction. After naturally cooling to 25 °C, the mixture is rinsed 2–3 times with deionized water and anhydrous ethanol, respectively, and then dried in air at 45–65 °C for 2.5–3.5 hours. Finally, the obtained product is placed in an alumina boat and calcined at 450–750 °C for 1.5–2.5 hours, and then naturally cooled to 25 °C to obtain the Ce-MOF derivative.

[0017] The second objective of this invention is to provide a Ce-MOF derivative electrode material, comprising an electrode substrate material and a Ce-MOF derivative material prepared by the above-described preparation method coated on the electrode substrate material.

[0018] In recent years, advanced oxidation technologies based on sulfate radicals have proven to be highly efficient for the removal of various poorly soluble organic compounds. The basic principle involves breaking the O2O bonds of persulfate (PDS) or permonosulfate (PMS) through heating, ultrasound, ultraviolet irradiation, transition metal oxides, and electrocatalysis to generate highly oxidizing SO4. − • , further undergoing redox reactions with organic matter. CeO2 can react with Ce based on changes in the partial pressure of oxygen in the environment. 3+ / Ce 4+ CeO2 can be interconverted between these two reactions and has been proven to be a catalyst for Fenton-like reactions. Therefore, CeO2 has been reported to be used directly as a catalyst for activating sodium persulfate. However, CeO2 metal oxides have poor conductivity and low utilization, which severely restricts their application in antibiotic wastewater treatment. Furthermore, due to the poor conductivity of CeO2 itself, it has not yet been used as an electrode material.

[0019] In our research on metal-organic coordination polymers (MOFs), we found that although the Ce-MOFs prepared in the experiment exhibited poor conductivity and limited Fenton-like degradation efficiency, after calcination, the resulting derivatives not only possessed the structure of CeO2 but also showed significantly enhanced conductivity and increased active sites, making them suitable as cathode materials for electro-activation in the electro-Fenton reaction. In experiments using this Ce-MOF derivative for the electrocatalytic oxidation degradation of levofloxacin hydrochloride, we found that its degradation effect was much better than that of CeO2 alone, and the electrode material was easily recyclable. Compared with other existing metal oxides used as electrocatalysts for degradation reactions, the electro-Fenton reaction efficiency of other metal oxides could not match the degradation effect achieved by the Ce-MOF derivative as the electrode material in this study.

[0020] Most existing research on the electrocatalytic oxidation degradation of antibiotics uses metal oxides directly loaded onto nickel foam as electrode materials. However, nickel foam, as a carrier, is easily oxidized and corroded during degradation, leading to difficulties in catalyst recovery and secondary pollution. Therefore, we chose carbon cloth, which is less reactive with the environment, as the electrode matrix material, and fabricated a Ce-MOF derivative electrode material with good stability and reusability. This electrode material effectively overcomes the shortcomings of traditional metal-organic framework materials Ce-MOF, such as poor conductivity and limited Fenton-like reaction degradation efficiency. It inherits the advantages of both components and generates more active catalytic sites, thereby effectively accelerating interfacial charge transfer during the electro-Fenton reaction and improving the efficiency of quinolone antibiotic degradation.

[0021] The third objective of this invention is to provide the application of Ce-MOF derivative materials prepared by the above-described preparation method or the above-described Ce-MOF derivative electrode materials in the degradation treatment of quinolone antibiotic wastewater.

[0022] Preferably, the steps for the degradation treatment of quinolone antibiotic wastewater are as follows:

[0023] (a) Add persulfate to quinolone antibiotic wastewater and then adjust the pH of the solution;

[0024] (b) Ce-MOF derivative material is coated on carbon cloth to obtain Ce-MOF derivative electrode material;

[0025] (c) The solution is stirred at a constant temperature, with Ce-MOF derivative electrode material as the cathode and platinum sheet as the anode, and quinolone antibiotic wastewater is degraded by constant current.

[0026] Preferably, the concentration of the quinolone antibiotic in step (a) is 10–50 mg / L. -1 The concentration of persulfate added is 0.1–0.5 g·L⁻¹. -1 The pH of the solution is 3–9.

[0027] Preferably, in step (b), the loading of Ce-MOF derivative on the Ce-MOF derivative electrode material is 7.5–20 mg.

[0028] Preferably, the current density in step (c) is 20–150 A·m. -2 .

[0029] Preferably, the quinolone antibiotic is levofloxacin.

[0030] In this invention, levofloxacin (LFX), an antibiotic, was used as an example to study its degradation effect. The main process of the levofloxacin (LFX) degradation experiment was as follows: At room temperature, Ce-MOF derivative material was coated onto carbon cloth to form an electrode. The Ce-MOF derivative electrode was used as the cathode, and a platinum electrode with the same dimensions as the cathode was used as the anode. The levofloxacin solution was degraded by electro-Fenton reaction in a 100 mL beaker, with stirring at 400–600 rpm and the temperature maintained at 25°C. The distance between the two electrodes was 1–2 cm. Under a stable current of DC power supply, the electrochemical oxidation of levofloxacin under different variable conditions was carried out. The changing conditions included the calcination temperature of the Ce-MOF derivative, the initial pH of the solution (3–9), and the initial concentration of levofloxacin (10–50 mg·L⁻¹). -1 ) and current density (20–150 A·m -2Catalyst loading (7.5–20 mg), sodium persulfate concentration (0.1–0.5 g·L⁻¹) -1 Sampling was conducted at fixed intervals of 10 minutes, and the LFX removal rate was used as the evaluation index to assess the degradation effect. The degradation efficiency of levofloxacin = (C0 - C...) t ) / C0× 100%, where C0 and C t These are the initial value and the measured value at time t for the concentration of levofloxacin hydrochloride.

[0031] The experiment found that the optimal parameters for the degradation of levofloxacin hydrochloride wastewater by electrodes prepared using synthesized Ce-MOF derivatives were: an initial concentration of 20 mg·L⁻¹. -1 At that time, Ce-MOF-550 with a load of 0.015 g was used as the cathode material, and the current density was 100 A·m. -2 The optimal conditions for this degradation study were a pH of 5.0, and the degradation rate reached 82% after 60 minutes, indicating that the Ce-MOF derivative electrode material has a good degradation effect on levofloxacin.

[0032] The present invention has the following beneficial effects:

[0033] (1) The Ce-MOF derivative material prepared by the present invention effectively overcomes the shortcomings of poor conductivity and limited degradation efficiency of traditional metal-organic framework material Ce-MOF in Fenton-like reaction, and inherits the advantages of both components. Since Ce-MOF generates more active catalytic sites after calcination, it can effectively accelerate the interfacial charge transfer during electro-Fenton reaction and improve the electrocatalytic oxidation efficiency when used as an electrode material.

[0034] (2) This invention applies Ce-MOF derivative materials to the electro-Fenton degradation reaction of quinolone antibiotics. Because the Ce-MOF derivative has a large number of oxygen vacancies and a high specific surface area, it can provide more electrochemical active sites, effectively promoting the rate of redox reactions during degradation. In the degradation of LFX, due to a series of redox reactions between PDS and Ce, Ce(III) / Ce(IV) promotes the degradation of S2O8. 2- To SO4 − The transformation of • promotes the generation of a large number of persulfate free radicals, thereby promoting the electro-Fenton reaction and significantly improving the degradation effect of LFX.

[0035] (3) The present invention uses Ce-MOF derivatives as electrode materials. The preparation process is simple, easy to recycle and reuse, and will not cause secondary pollution to antibiotic wastewater, thus providing a possibility for practical application. Attached Figure Description

[0036] Figure 1This is the SEM image of Ce-MOF-550 in Implementation Case 1.

[0037] Figure 2 The graph shows the removal rate curves of Ce-MOF derivative levofloxacin hydrochloride at different calcination temperatures in Example 5.

[0038] Figure 3 This is a graph showing the removal rate of levofloxacin hydrochloride under different pH conditions in Example 6.

[0039] Figure 4 The graph shows the removal rate curves of levofloxacin hydrochloride under different Ce-MOF-550 loading conditions in Example 7.

[0040] Figure 5 The graph shows the removal rate curves of levofloxacin hydrochloride under different concentrations of sodium persulfate in Example 8.

[0041] Figure 6 The graph shows the removal rate curves of levofloxacin hydrochloride under different current densities in Example 9.

[0042] Figure 7 The graph shows the removal rate curves of levofloxacin hydrochloride under different initial LFX concentrations in Example 10.

[0043] Figure 8 The graph shows the removal rate of levofloxacin hydrochloride under the condition of recycling a Ce-MOF derivative cathode material 5 times in Example 11.

[0044] Figure 9 The graph shows the removal rate of levofloxacin hydrochloride in the comparative example under the condition of using an iron-based metal catalyst as the electrode material. Detailed Implementation

[0045] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below are generally only some, not all, of the embodiments of the present invention. Therefore, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0046] Example 1

[0047] Synthesis methods of Ce-MOF and calcination process of Ce-MOF derivatives

[0048] A cerium salt precursor solution was prepared for hydrothermal synthesis. 3.86 g of Ce(NO3)3·6H2O and 2.06 g of C9H6O6 were dissolved separately in 30 mL of DMF solution and stirred for 20 minutes until completely dissolved. The two solutions were then mixed and stirred for 30 minutes until homogeneous. The mixture was then transferred to a PTFE autoclave and heated in an oven at 100 °C for 24 h to carry out the hydrothermal reaction. After naturally cooling to 25 °C, the mixture was rinsed 2–3 times with deionized water and anhydrous ethanol, respectively, and then dried in air at 60 °C for 6 h to obtain Ce-MOF. Finally, the obtained product was placed in an alumina boat and calcined at 550°C for 2 hours, then naturally cooled to 25°C to obtain the Ce-MOF derivative, namely Ce-MOF-550 (in the experiment, when all conditions except calcination temperature were the same as in this example, we numbered them according to calcination temperature to better distinguish the Ce-MOF derivatives obtained under different calcination temperature conditions). The SEM characterization image of Ce-MOF-550 is shown below. Figure 1 As shown, through analysis Figure 1 The SEM characterization image shown reveals that it exhibits a rod-like structure with pores within the intact rod-like structure, which enhances the electrocatalytic active center and improves electrochemical performance.

[0049] Example 2

[0050] Synthesis methods of Ce-MOF and calcination process of Ce-MOF derivatives

[0051] A cerium salt precursor solution was prepared for hydrothermal synthesis. 3.86 g of Ce(NO3)3·6H2O and 0.94 g of C9H6O6 were dissolved separately in 30 mL of DMF solution and stirred for 20 minutes until completely dissolved. The solutions were then mixed and stirred for 30 minutes until homogeneous. The mixture was then transferred to a PTFE autoclave and heated in an oven at 120 °C for 20 h for hydrothermal reaction. After naturally cooling to 25 °C, the product was rinsed 2–3 times with deionized water and anhydrous ethanol, respectively, and then dried in air at 60 °C for 6 h to obtain Ce-MOF. Finally, the obtained product was placed in an alumina boat and calcined at 550 °C for 2 h, then naturally cooled to 25 °C to obtain the Ce-MOF derivative.

[0052] Example 3

[0053] Synthesis methods of Ce-MOF and calcination process of Ce-MOF derivatives

[0054] A cerium salt precursor solution was prepared for hydrothermal synthesis. 3.86 g of Ce(NO3)3·6H2O and 3.74 g of C9H6O6 were dissolved separately in 30 mL of DMF solution and stirred for 20 minutes until completely dissolved. The solutions were then mixed and stirred for another 30 minutes until homogeneous. The mixture was then transferred to a PTFE autoclave and heated in an oven at 130 °C for 30 h for hydrothermal reaction. After naturally cooling to 25 °C, the product was rinsed 2–3 times with deionized water and anhydrous ethanol, respectively, and then dried in air at 60 °C for 6 h to obtain Ce-MOF. Finally, the obtained product was placed in an alumina boat and calcined at 550 °C for 2 h, then naturally cooled to 25 °C to obtain the Ce-MOF derivative.

[0055] Example 4

[0056] Preparation of Ce-MOF derivative electrode materials

[0057] The carbon cloth is pretreated to remove surface impurities and ensure good adhesion between the cerium-based derivative material and the carbon cloth without interference from other ions. First, the raw carbon cloth is soaked in a mixture of concentrated sulfuric acid and concentrated nitric acid (3:1 volume ratio) for 12 hours. Then, it is rinsed 3 to 4 times with deionized water and ultrasonically vibrated in a beaker containing deionized water for 20 minutes to thoroughly remove residual sulfuric acid and nitric acid. It is then washed with distilled water and anhydrous ethanol until neutral to remove impurities and improve the hydrophilicity of the carbon cloth. Finally, it is dried in a vacuum oven at 60°C. The Ce-MOF derivative is then coated onto a 2cm × 2cm piece of carbon cloth to form the electrode material.

[0058] Example 5

[0059] Effect of calcination temperature of Ce-MOF derivatives on the degradation efficiency of levofloxacin

[0060] By changing only the calcination temperature of Ce-MOF in Example 1, while keeping other preparation processes the same, Ce-MOF derivatives at different calcination temperatures were obtained. These Ce-MOF derivatives synthesized at different calcination temperatures were then used for electro-Fenton oxidation degradation of levofloxacin wastewater. In a 100 mL beaker, 50 mL of a 20 mg / L levofloxacin hydrochloride solution was subjected to Fenton-like degradation with stirring at 500 rpm and the temperature maintained at room temperature (25°C). 15 mg of Ce-MOF derivatives from different calcination temperatures were coated onto a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet as the anode. Furthermore, under stable DC current conditions, with a 1 cm distance between the two electrodes, 15 mg of Na₂S₂O₈ was added for electrochemical oxidation of LFX. Specifically, the initial concentration was 20 mg / L… -1 Levofloxacin wastewater with a current density of 50 A·m -2With a Ce-MOF derivative loading of 15 mg, a sodium persulfate concentration of 0.3 g / L, and a pH of 5, the LFX degradation rate was tested over time by varying the calcination temperature of Ce-MOF. The curve of LFX removal rate over time is shown below. Figure 2 As shown. By Figure 2 It can be seen that under the conditions of no catalyst, 15 mg Ce-MOF, 15 mg Ce-MOF-450, 15 mg Ce-MOF-550, 15 mg Ce-MOF-650, and 15 mg Ce-MOF-750, the degradation rates of LFX at 60 min were 50.61%, 60.51%, 65.71%, 72.90%, 66.93%, and 62.05%, respectively. Within the same degradation time, the degradation rate of LFX increased when the calcination temperature of the Ce-MOF derivative increased from 450℃ to 550℃, and gradually decreased from 550℃ to 750℃, indicating that 550℃ is the optimal temperature for calcination treatment of the Ce-MOF derivative.

[0061] Example 6

[0062] Effect of solution pH on the degradation efficiency of levofloxacin

[0063] The Ce-MOF-550 synthesized in Example 1 was used for electro-Fenton oxidation degradation of levofloxacin wastewater. Electro-Fenton degradation of 50 mL of a 20 mg / L levofloxacin hydrochloride solution was carried out in a 100 mL beaker with stirring at 700 rpm and the temperature maintained at room temperature (25 °C). 15 mg of Ce-MOF-550 was coated on a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Furthermore, under stable current conditions from a DC power supply, the distance between the two electrodes was 1.2 cm. 15 mg of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the initial concentration was 20 mg / L. -1 Levofloxacin wastewater with a current density of 50 A·m -2 With a Ce-MOF derivative loading of 15 mg and a sodium persulfate concentration of 0.3 g / L, the pH was varied, and the LFX degradation rate was tested over time. The curve showing the LFX removal rate over time is shown below. Figure 3 As shown. By Figure 3 It can be seen that the degradation rates of LFX are 56.33%, 71.90%, 70.43%, and 67.60% when pH = 3, 5, 7, and 9, respectively. Within the same degradation time, the degradation rate is highest at pH = 5, and the degradation rate decreases as pH increases.

[0064] Example 7

[0065] Effect of different loadings of Ce-MOF derivatives in electrode materials on the degradation efficiency of levofloxacin

[0066] Ce-MOF-550 synthesized in Example 1 was used to perform Fenton-like oxidation degradation of levofloxacin wastewater. In a 100 mL beaker, 50 mL of a 20 mg / L levofloxacin hydrochloride solution was subjected to Fenton-like degradation with stirring at 500 rpm and the temperature maintained at room temperature (25°C). A certain amount of Ce-MOF-550 was coated onto a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Furthermore, under stable current conditions with a DC power supply, the distance between the two electrodes was 1 cm, and 15 mg of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the initial concentration was 20 mg / L. -1 Levofloxacin wastewater with a current density of 50 A·m -2 With a sodium persulfate concentration of 0.3 g / L and a pH of 5, the degradation rate of LFX was tested over time by varying the Ce-MOF derivative loading. The curve of LFX removal rate over time is shown below. Figure 4 As shown. By Figure 4 It can be seen that when the Ce-MOF-550 loading is 7.5 mg, 10 mg, 12.5 mg, 15 mg, 17.5 mg, and 20 mg, the degradation rates of LFX are 51.51%, 57.18%, 65.44%, 73.10%, 67.87%, and 63.27%, respectively. Within the same degradation time, the degradation rate of LFX increases when the Ce-MOF-550 loading increases from 7.5 mg to 15 mg, and gradually decreases when the loading increases from 15 mg to 20 mg.

[0067] Example 8

[0068] Effect of sodium persulfate concentration on the degradation efficiency of levofloxacin

[0069] Ce-MOF-550 synthesized in Example 1 was used to perform Fenton-like oxidation degradation of levofloxacin wastewater. A 50 mL solution of 20 mg / L levofloxacin hydrochloride was subjected to Fenton-like degradation in a 100 mL beaker, stirred at 500 rpm, and maintained at room temperature (25 °C). 15 mg of Ce-MOF-550 was coated on a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Under stable DC current conditions, the distance between the two electrodes was 1 cm, and a certain amount of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the initial concentration was 20 mg / L. -1 Levofloxacin wastewater with a current density of 50 A·m -2 With a Ce-MOF derivative loading of 15 mg and a pH of 5, the LFX degradation rate was tested over time by varying the sodium persulfate concentration. The curve of LFX removal rate over time is shown below. Figure 5 As shown. By Figure 5 It can be seen that when the concentration of sodium persulfate is 0.1 g·L⁻¹-1 0.2 g·L -1 0.3 g·L -1 0.4 g·L -1 0.5 g·L -1 At the same time, the degradation rates of LFX were 54.56%, 64.17%, 73.10%, 58.32%, and 48.66%, respectively. Within the same degradation time, the sodium persulfate concentration increased from 0.1 g·L⁻¹. -1 Up to 0.5 g·L -1 At that time, the degradation rate of LFX first increased and then decreased, and the degradation rate of LFX was the highest when the sodium sulfate concentration was 0.3 g / L.

[0070] Example 9

[0071] Test on the effect of current density on the degradation efficiency of levofloxacin

[0072] Ce-MOF-550 synthesized in Example 1 was used to perform Fenton-like oxidation degradation of levofloxacin wastewater. In a 100 mL beaker, 50 mL of a 20 mg / L levofloxacin hydrochloride solution was subjected to Fenton-like degradation with stirring at 500 rpm and the temperature maintained at room temperature (25°C). 15 mg of Ce-MOF-550 was coated on a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Furthermore, under stable current conditions with a DC power supply, the distance between the two electrodes was 1 cm, and 15 mg of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the initial concentration was 20 mg / L. -1 Levofloxacin wastewater with a Ce-MOF derivative loading of 15 mg, pH 5, and sodium persulfate concentration of 0.3 g / L was treated by varying the current density and testing the LFX degradation rate over time. The curve of LFX removal rate over time is shown below. Figure 6 As shown. By Figure 6 It can be seen that when the current density is 20 A·m -2 40A·m -2 50A·m -2 75A·m -2 100A·m -2 150A·m -2 At 60 min, the degradation rates of LFX were 52.47%, 69.52%, 72.93%, 82.05%, and 83.40%, respectively. Within the same degradation time, when the current density increased from 20 A·m⁻¹... -2 Increased to 150 A·m -2 As the current density reached 100 A·m, the degradation rate of LFX gradually increased, and when the current density reached 100 A·m -2 Afterwards, the increase in LFX degradation rate did not change significantly.

[0073] Example 10

[0074] Effect of different initial LFX concentrations on the degradation efficiency of levofloxacin

[0075] Ce-MOF-550 synthesized in Example 1 was used to perform Fenton-like oxidation degradation of levofloxacin wastewater. In a 100 mL beaker, 50 mL of a 20 mg / L levofloxacin hydrochloride solution was used for Fenton-like degradation with stirring at 500 rpm and the temperature maintained at room temperature (25°C). 15 mg of Ce-MOF-550 was coated on a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Furthermore, under stable DC current conditions, the distance between the two electrodes was 1 cm, and 15 mg of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the Ce-MOF derivative loading was 15 mg, the pH was 5, the sodium persulfate concentration was 0.3 g / L, and the current density was 100 A·m⁻¹. -2 At that time, the initial concentration of LFX was changed, and the LFX degradation rate was tested over time. The curve of LFX removal rate over time is shown in Figure 1. Figure 7 As shown. By Figure 7 It can be seen that when the initial LFX concentration is 10 mg·L⁻¹, -1 20 mg·L -1 30 mg·L -1 40 mg·L -1 50 mg·L -1 At the same time, the degradation rates of levofloxacin hydrochloride were 85.35%, 82.05%, 77.28%, 74.20%, and 71.35%, respectively. Within the same degradation time, the lower the initial concentration of LFX, the higher the degradation rate of LFX.

[0076] The experimental results above show that the optimal parameters for the electrode preparation using the synthesized Ce-MOF derivative to degrade levofloxacin hydrochloride wastewater are set at an initial concentration of 20 mg·L⁻¹. -1 At that time, Ce-MOF-550 with a load of 0.015 g was used as the cathode material, and the current density was 100 A·m. -2 The optimal conditions for this degradation study were a pH of 5.0, and the degradation rate reached 82% after 60 minutes, indicating that the electrode has a good degradation effect on levofloxacin.

[0077] Example 11

[0078] Electrocatalytic cycling performance test of Ce-MOF derivative electrode materials for the electro-Fenton oxidation degradation of levofloxacin

[0079] Ce-MOF-550 synthesized in Example 1 was used to perform Fenton-like oxidation degradation of levofloxacin wastewater. In a 100 mL beaker, 50 mL of a 20 mg / L levofloxacin hydrochloride solution was subjected to Fenton-like degradation with stirring at 500 rpm and the temperature maintained at room temperature (25°C). 15 mg of Ce-MOF-550 was coated on a 2 cm × 2 cm carbon cloth as the cathode, and a platinum sheet was used as the anode. Under stable current conditions from a DC power supply, the distance between the two electrodes was 1 cm. 15 mg of Na₂S₂O₈ was added for electrochemical oxidation. Specifically, the initial concentration was 20 mg / L… -1 Levofloxacin wastewater with a Ce-MOF derivative loading of 15 mg, pH 5, and sodium persulfate concentration of 0.3 g / L exhibited a current density of 100 A·m. -2 The degradation rate of levofloxacin hydrochloride (LFX) was tested by recycling the same Ce-MOF derivative cathode material five times over time. The curve of LFX removal rate over time is shown below. Figure 8 As shown. By Figure 8 It can be seen that in the five-cycle experiment, the degradation rates were 82.05%, 81.58%, 80.92%, 79.95%, and 78.86%, respectively. The change in degradation effect between adjacent cycles was less than 1%. In the fifth cycle degradation experiment, the degradation rate of levofloxacin still reached an excellent effect of 78.86%. The experimental results show that the Ce-MOF derivative electrode material has strong recyclability.

[0080] Comparative Example

[0081] Electro-Fenton testing of levofloxacin was performed using conventional iron-based metal catalyst electrode materials.

[0082] Iron oxide was synthesized at 60℃ using FeCl3·6H2O and NaOH in a specific ratio, and the resulting powdered catalyst was dried and ground. A cathode was prepared by coating 15 mg of iron oxide onto a 2 cm × 2 cm carbon cloth, and a platinum sheet was used as the anode. Electrochemical oxidation was performed under a stable DC current with a 1 cm distance between the two electrodes, and 15 mg of Na2S2O8 was added. Specifically, the initial concentration was 20 mg·L⁻¹. -1 Levofloxacin wastewater with a current density of 50 A·m -2 At a sodium persulfate concentration of 0.3 g / L and a pH of 5, the LFX degradation rate was tested over time by varying the iron oxide loading. The curve showing the LFX removal rate over time is shown below. Figure 9 As shown. By Figure 9It can be seen that when the iron oxide loading is 7.5 mg, 10 mg, 12.5 mg, 15 mg, 17.5 mg, and 20 mg, the degradation rates of LFX are 38.76%, 43.93%, 49.37%, 56.18%, 62.87%, and 65.27%, respectively. Comparing the experimental results of Ce-MOF-550 material in Example 7, it can be concluded that using iron oxide as a catalyst for the electro-Fenton reaction, under the same conditions, results in a significantly lower electrocatalytic degradation rate of levofloxacin than that of the Ce-MOF derivative, and requires more catalyst.

Claims

1. The application of a Ce-MOF derivative electrode material in the degradation of quinolone antibiotics in wastewater by activating persulfate, characterized in that... The Ce-MOF derivative electrode material includes an electrode substrate material and a Ce-MOF derivative material coated on the electrode substrate material. The preparation method of the Ce-MOF derivative material includes the following steps: (1) Disperse cerium nitrate hexahydrate in N,N-dimethylformamide to obtain solution A; (2) Disperse 1,3,5-benzenetricarboxylic acid in N,N-dimethylformamide to obtain solution B; (3) Mix the above solutions A and B evenly, and then put them into a reaction vessel for hydrothermal reaction. After the reaction is completed, cool to room temperature to obtain the reaction solution; (4) Centrifuge the above reaction solution, wash the obtained product and dry it to obtain Ce-MOF; (5) Ce-MOF was calcined at 450~750℃ to obtain Ce-MOF derivatives.

2. The application as described in claim 1, characterized in that, In step (3), the molar ratio of cerium nitrate hexahydrate to 1,3,5-benzenetricarboxylic acid in the mixture of A and B is 1:0.5-2.

3. The application as described in claim 1 or 2, characterized in that, The hydrothermal reaction temperature in step (3) is 100~130℃ and the time is 20~30h.

4. The application as described in claim 1, characterized in that, The steps for the degradation treatment of quinolone antibiotic wastewater are as follows: (a) Add persulfate to quinolone antibiotic wastewater and then adjust the pH of the solution; (b) Ce-MOF derivative material is coated on carbon cloth to obtain Ce-MOF derivative electrode material; (c) The solution is stirred at a constant temperature, with Ce-MOF derivative electrode material as the cathode and platinum sheet as the anode, and quinolone antibiotic wastewater is degraded by constant current.

5. The application as described in claim 1, characterized in that, In step (a), the concentration of the quinolone antibiotic is 10–50 mg / L. -1 The concentration of persulfate added is 0.1–0.5 g·L⁻¹. -1 The pH of the solution is 3–9.

6. The application as described in claim 1 or 5, characterized in that, In step (b), the loading of Ce-MOF derivatives on the Ce-MOF derivative electrode material is 7.5–20 mg.

7. The application as described in claim 6, characterized in that, The current density in step (c) is 20–150 A·m. -2 .

8. The application as described in claim 1 or 5, characterized in that, The quinolone antibiotic in question is levofloxacin.

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