Application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics using electro-Fenton-like methods.

Abstract

This invention relates to the application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics, similar to electro-Fenton degradation. The phosphorus vacancy-mediated transition metal-based cathode material is NiCoP-V. p Using nickel foam as a substrate, a NiCoP catalyst containing phosphorus vacancies is supported on the surface of the substrate. The phosphorus-vacancy-containing NiCoP catalyst is in the form of nanoneedles with numerous pores on its surface. This phosphorus-vacancy-containing transition metal-based catalyst of the present invention exhibits faster electron transport efficiency, a relatively larger electrochemical active area, and can expose more active sites, selectively achieving 100% removal of metronidazole. The fully exposed active sites provide more sites for the adsorption and activation of H₂O₂ and O₂, and the enhanced charge transfer can accelerate the redox cycle of the transition metal. Both synergistically regulate the generation of superoxide radicals O₂. 2· ‑ Together with high-valence metal oxygen, it ultimately achieves selective and efficient degradation of metronidazole antibiotics.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and in particular refers to the application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics in a Fenton-like manner. Background Technology

[0002] In recent years, nitroimidazole antibiotics (such as metronidazole) have been widely used due to their broad antibacterial spectrum and low price. However, their high water solubility, low biodegradability, and potential ecotoxicity lead to their continuous accumulation in the environment, posing a threat to aquatic ecosystems and human health. Traditional biological treatment technologies have limited removal efficiency for these antibiotics. Electro-Fenton technology in advanced oxidation processes (AOPs) has attracted much attention for its efficient degradation through the in-situ generation of hydroxyl radicals (·OH).

[0003] Electro-Fenton technology generates hydrogen peroxide (H2O2) through the two-electron oxygen reduction reaction (ORR) at the cathode, which is then converted into other reactive oxygen species (ROS) that can oxidize and degrade pollutants, thereby achieving wastewater purification. Electro-Fenton cathode materials are primarily iron-based, which suffers from limited exposure of active sites and low electron / mass transfer efficiency, resulting in low O2 utilization and Fe content during the electro-Fenton process. 3+ / Fe 2+ Insufficient cycle efficiency and ROS generation severely restrict its degradation efficiency and industrial application. Developing efficient and stable Fenton-like cathode materials by replacing traditional iron-based materials with ferro-like transition metal materials to simultaneously improve the exposure of active sites and electron / mass transfer efficiency has become one of the current research hotspots in this field.

[0004] Transition metal phosphides (TMPs) exhibit unique advantages in electro-Fenton-like systems due to their easily tunable electronic structure, classic electronic conduction effects, and outstanding catalytic performance. However, most TMPs have poor electrical conductivity, which limits the degradation performance of antibiotics. Introducing or manipulating lattice vacancies (such as oxygen vacancies and metal vacancies) can disrupt the original electron cloud distribution of the material, releasing free electrons, thereby increasing the carrier concentration and providing more space and pathways for electron transport. This reduces obstacles in electron transport, allowing the material to maintain high conductivity and solving the problem of poor conductivity in transition metal phosphides. Compared to the more common oxygen vacancies, phosphorus vacancy engineering has greater advantages. First, because the electronegativity of P atoms (2.19) is lower than that of O atoms (3.44), it is easier to form highly reducing active sites on the material surface, giving it unique chemical activity and selectivity. Phosphorus vacancies can induce electron enrichment on adjacent metal atoms and phosphorus atoms, providing more electrons for electrocatalytic reactions. In addition, phosphorus vacancies can regulate the hybridization degree of transition metal d orbitals and P2p orbitals, causing changes in electron cloud distribution, optimizing the adsorption and activation pathways of O2 and H2O2, and promoting the degradation reaction.

[0005] In summary, addressing the problems of limited active site exposure and low electron transport efficiency in Fenton cathode materials, leading to low O2 utilization and insufficient ROS generation during the electro-Fenton process, this invention proposes the preparation of phosphorus vacancy (V) sites. P The transition metal-based catalyst mediated by phosphorus vacancies promotes the generation of more ROS on the cathode catalyst surface by regulating the electronic structure and accelerating electron transfer, thereby improving the selective degradation performance of metronidazole similar to that of electroFenton. Summary of the Invention

[0006] To address the above technical problems, this invention provides an application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics using an electro-Fenton-like method. Compared with catalysts without phosphorus vacancies, traditional oxide catalysts, and catalysts containing oxygen vacancies, the phosphorus vacancy-containing transition metal-based catalyst proposed in this invention exhibits faster electron transport efficiency, a relatively larger electrochemical active area, and exposes more active sites. The fully exposed active sites provide more sites for the adsorption and activation of H₂O₂ and O₂, and the enhanced charge transfer accelerates the redox cycle of the transition metal. These two processes synergistically regulate the generation of superoxide radicals (O₂). 2· - Together with high-valence metal oxygen, it ultimately achieves 100% selective degradation of metronidazole.

[0007] The purpose of this invention is to provide an application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics, similar to electro-Fenton degradation. The phosphorus vacancy-mediated transition metal-based cathode material is NiCoP-V.p Using nickel foam as a substrate, a NiCoP catalyst containing phosphorus vacancies is loaded on the surface of the substrate; the NiCoP catalyst containing phosphorus vacancies is in the form of nanoneedles and has a large number of pores on its surface.

[0008] In some embodiments of the present invention, the phosphorus vacancy-mediated transition metal-based cathode material is prepared by the following method: A mixed solution of nickel source, cobalt source, urea, and NH4F is provided; The substrate electrode is immersed in the mixed solution to carry out a hydrothermal reaction, thereby obtaining a substrate electrode loaded with a nickel-cobalt precursor. In an inert atmosphere, a substrate electrode loaded with nickel-cobalt precursor is placed in a tube furnace, and a phosphorus source is placed upstream of a quartz tube in the tube furnace. The electrode is heated and calcined to perform phosphating treatment, thereby obtaining a substrate electrode loaded with nickel-cobalt phosphide. The substrate electrode loaded with nickel-cobalt phosphide is placed in an etching solution for etching and reduction treatment to obtain the phosphorus vacancy-mediated transition metal-based cathode material.

[0009] In some embodiments of the present invention, the nickel source is selected from one or more of Ni(NO3)2·6H2O, Ni(NO3)2·9H2O and NiCl2·4H2O; The cobalt source is selected from one or more of Co(NO3)2·6H2O, CoSO4·7H2O and CoCl2·6H2O; The molar ratio of the cobalt source, nickel source, urea, and NH4F is 2:1:(6~9):(2~5).

[0010] In this invention, ammonium fluoride plays a morphology-guiding role. Firstly, the strong coordination ability of fluoride ions can form stable complexes with nickel and cobalt ions, slowing down the direct reaction and precipitation rate between metal ions and hydroxide ions. Furthermore, fluoride ions tend to preferentially adsorb on specific crystal faces of the growing precursor particles. This adsorption inhibits the growth rate of these crystal faces, thereby altering the relative growth rates between different crystal faces. Finally, by synergistically controlling nucleation and growth kinetics with urea, a precursor with better crystallinity can be formed.

[0011] In some embodiments of the present invention, the substrate electrode is selected from one or more of nickel foam (NF), copper foam (CF), and titanium foam (TF).

[0012] In some embodiments of the present invention, the reaction temperature of the hydrothermal reaction is 100~120°C, which can be 100, 110, 120°C, or any range between any two values, and the reaction time is 6~8 h, which can be 6, 6.5, 7, 7.5, 8 h, or any range between any two values, exemplarily.

[0013] In some embodiments of the present invention, the inert gas in the inert atmosphere includes nitrogen and / or argon; The phosphorus source is selected from one or more of NaH2PO2, NaH2PO2·H2O and Ca(H2PO2)2; The amount of phosphorus source depends on the surface area of ​​the nickel-cobalt precursor; specifically, the amount of phosphorus source used ranges from 0.0004 g / cm³. 2 -0.0006 g / cm 2 .

[0014] In some embodiments of the present invention, the heating rate of calcination is 2~10℃ / min, the calcination temperature is 300~500℃, and exemplarily, it can be 300, 350, 400, 450, 500℃, or any range between any two values; the calcination time is 2~3 h, and exemplarily, it can be 2, 2.5, 3 h, or any range between any two values.

[0015] In some embodiments of the present invention, the etching solution comprises a NaBH4 solution, and the concentration of the etching solution is 0.01~0.10 M. Exemplarily, it can be 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.10 M, or any range between any two values. The etching-reduction time is 2~15 min; exemplarily, it can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15 min, or any range between any two values. The phosphorus-vacancy-containing transition metal-based electrocatalyst of the present invention can induce the generation of phosphorus vacancies through sodium borohydride etching, thereby regulating the generation of superoxide radicals and high-valence metal oxygen.

[0016] The concentration of metronidazole antibiotics in wastewater is 10~40 mg / L. For example, it can be 10, 20, 30, 40 mg / L, or any range between any two values. The pH of the metronidazole antibiotic wastewater is 3-12; more preferably, the pH is 3-6, 6-7, or 7-12. During the electro-Fenton degradation treatment, the external power supply is a DC power supply, and the current density is controlled between 10 and 40 mA / cm². 2 For example, the values ​​can be 10, 20, 30, or 40 mA / cm. 2 Or any interval between any two values; In some embodiments of the present invention, the size of the pore is 5~10 nm.

[0017] The technical solution of the present invention has the following advantages compared with the prior art: Morphological advantages: NaBH4 provides H with strong reducing power. * The phosphorus phosphide reacts with phosphorus (P) on NiCoP to form PH3 gas, resulting in the loss of P sites on NiCoP and the creation of phosphorus vacancies. This causes the phosphorus-vacancy-containing nickel-cobalt phosphide to exhibit a nanoneedle-like morphology, with pores of approximately 5–10 nm formed on its surface. This morphological structure increases its specific surface area to 27.08 m². 2 / g, while the surface is rougher, which can expose more active sites and promote the adsorption and activation of H2O2 and O2; Electronic structure optimization: There is a synergistic effect between the two transition metal sites, which can accelerate the cycling of the transition metal redox couple; in addition, phosphorus vacancies can induce electron enrichment on adjacent metal atoms and phosphorus atoms, providing more electrons for electrocatalytic reactions; at the same time, it can weaken the dp orbital hybridization of transition metal and phosphorus, change the electron cloud distribution, and optimize the adsorption and activation pathways of O2 and H2O2. Synergistic Pathway of Superoxide and High-Valence Metal Oxygen: Phosphorus vacancy-mediated bimetallic catalysts can simultaneously generate superoxide radicals and high-valence metal oxygen. Through synergistic effects such as electron transfer, complementary active sites, and optimized reaction pathways, they significantly improve catalytic efficiency and selectivity. High-valence metal oxygen is a strong oxidizing site and can act as an electron acceptor to promote the single-electron reduction of O2 to ·O2⁻ (O2 + e⁻ → ·O2⁻), lowering the energy barrier for ·O2⁻ formation; it can also promote the oxidation of H2O2 to ·O2⁻ (H2O2 → ·O2). − + H + + e - This leads to the generation of more superoxide radicals on the electrode surface. Simultaneously, ·O2 - O2⁻ is not particularly oxidizing, so relying solely on it to degrade pollutants is usually not ideal. However, by combining it with high-valence metal oxygen to synergistically attack pollutants and reducing the activation energy of the reaction through "relay oxidation", the problem of poor degradation performance of metronidazole by a single active species can be avoided.

[0018] Wide range of applications for degradation: NiCoP-V p The electro-Fenton-like system with the cathode selectively achieved 100% removal of metronidazole within 30 minutes, and the removal rate of metronidazole remained stable at over 95% after 5 cycles of degradation. 2+ and Co 2+ The leaching value meets the "Integrated Wastewater Discharge Standard" (GB 8978-1996). More importantly, the system exhibits leaching values ​​within the range of 10-40 mA cm⁻¹. -2It exhibits relatively excellent catalytic activity against pollutants at current densities of 10-40 mg / L and at a wide pH range (3-12), while also resisting coexisting substances in water (such as Cl). − HCO3 − CO3 2− NO3 − Interference from humic acid. Attached Figure Description

[0019] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 The NiCoP-V material obtained in Example 1 of this invention p SEM image; Figure 2 The NiCoP-V material obtained in Example 1 of this invention p EPR spectrum of phosphorus vacancies; Figure 3 The electro-Fenton-like degradation performance of six different transition metal-based catalysts; Figure 4 These are the EPR spectra of different capture agents added in Example 1 of this invention; Figure 5 This is the electro-Fenton-like degradation performance of Example 1 of the present invention in the presence of background substances (different anions and humic acids) in water. Figure 6 This is a graph showing the degradation performance of the cyclic experiment in Example 1 of the present invention; Figure 7 The NiCoP-V material obtained in Example 1 of this invention p Electro-Fenton-like degradation efficiency at different initial pH levels; Figure 8 The NiCoP-V material obtained in Example 1 of this invention p Electro-Fenton-like degradation performance for different pollutants; Figure 9 The NiCoO-V material obtained in Comparative Example 5 of this invention o The degradation performance diagram of the cyclic experiment. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0021] The application of a phosphorus vacancy-mediated transition metal-based cathode material proposed in this invention for the selective degradation of metronidazole antibiotics using an electro-Fenton-like method involves a transition metal phosphide (NiCoP-V) loaded with phosphorus vacancies. p This was achieved by constructing an electro-Fenton-like system using the substrate electrode as the cathode. The electro-Fenton-like system is based on NiCoP-V... p The cathode is a 0.1M anhydrous sodium sulfate solution, and the anode is a DSA electrode. Metronidazole is degraded using this method. The phosphorus vacancy-mediated transition metal phosphide prepared in this invention, through bimetallic synergy and the dual effect of phosphorus vacancies, has more active sites, optimized electronic structure, and faster electron transfer. This optimizes the adsorption and activation pathways of O2 and H2O2, promoting the generation of superoxide radicals and high-valence metal oxygen. These two factors synergistically enhance the selective catalytic degradation efficiency of metronidazole and exhibit excellent cycling stability and broad environmental adaptability.

[0022] In this invention, the preparation method of the phosphorus-vacancy-containing transition metal-based Fenton cathode material is as follows: Co(NO3)2·6H2O: Ni(NO3)2·6H2O: urea: NH4F are dissolved in 30 mL of deionized water in a molar ratio of 2:1:9:3. Then, the mixed solution and pretreated nickel foam (2 cm × 5 cm) are transferred to a 50 mL stainless steel autoclave for reaction. The reaction temperature is 120±5℃, and the reaction time is 6~7 h. After the reaction is completed, the mixture is rinsed alternately with ethanol and water, and finally dried under vacuum at 60℃ for 6 h. In the second step, the nickel foam loaded with nickel-cobalt precursor is transferred to the downstream of a quartz tube, and NaH2PO2 (0.5 g) is placed on the upstream side of the quartz tube as a pH3 source. Under a nitrogen atmosphere, the temperature is increased to 350±5℃ at a rate of 5℃ / min, and calcined for 2~3 h to obtain nickel foam loaded with nickel-cobalt phosphide. Finally, the nickel foam loaded with nickel cobalt phosphide was immersed in 0.05 M (100 mL 0.2 g) NaBH4 solution and etched for 10 min to obtain the phosphorus vacancy-mediated NiCoP / NF cathode material.

[0023] In this invention, the specific process steps for the phosphorus vacancy-mediated selective degradation of metronidazole using a transition metal-based cathode material similar to an electro-Fenton reactor are as follows: After connecting the external power supply, the stirrer is turned on, and the metronidazole in the reactor begins to be degraded. The metronidazole degradation process lasts for 20-30 minutes. During this period, 1 mL samples are taken at 0, 2, 5, 10, 15, 20, and 30 minutes. All water samples are filtered using a 0.22 μm filter, and the degradation efficiency of metronidazole is then evaluated using high-performance liquid chromatography. A horizontally oriented fixing device is provided above the reactor. The anode and cathode are fixed by fixing electrode clamps within these holes, maintaining a distance of 30 mm between the electrodes. The anode and cathode used should be of equal size and placed parallel to each other, each measuring 2 × 5 cm.2 After the electrode clamps are fixed, the anode and cathode should be immersed 2-4 cm below the solution. The anode and cathode are connected to a linearly adjustable DC regulated power supply via wires, with the current controlled at 10-40 mA / cm². 2 The cathode is NiCoP-V. P The anode is a DSA electrode, and the electrolyte is a 0.1 M anhydrous sodium sulfate solution. The electrolysis system also includes stirring and temperature control; the water temperature in the reactor is controlled at 30±5℃ by a heated magnetic stirrer.

[0024] In this invention, the pretreatment process of the cathode nickel foam substrate is as follows: In order to remove industrial grease residue on the surface of the nickel foam and enable the catalyst to grow uniformly on the surface of the nickel foam in situ, the nickel foam (2 cm × 5 cm) is pretreated by ultrasonic cleaning with acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water respectively for 30 min each. Finally, it is soaked in deionized water for later use.

[0025] The phosphorus vacancy-mediated transition metal-based cathode material prepared in this invention exhibits stronger catalytic activity and higher stability. Firstly, the presence of phosphorus vacancies optimizes the material morphology. Through... Figure 1 SEM images show NiCoP-V containing phosphorus vacancies. P The / NF exhibits a nanoneedle-like morphology with pores of 5-10 nm in diameter on its surface, making it rougher and exposing more active sites, thus promoting the adsorption and activation of H2O2 and O2. Secondly, the dual synergistic effect of bimetal and phosphorus vacancies can optimize the intrinsic electronic structure of the material, promote electron transfer, and optimize the adsorption and activation pathways of O2 and H2O2. Finally, the phosphorus vacancy-mediated bimetallic catalyst can simultaneously generate superoxide radicals and high-valence metal oxygen. Through synergistic effects such as electron transfer, complementary active sites, and optimized reaction pathways, the two can significantly improve the catalytic efficiency and selectivity of metronidazole.

[0026] By analyzing NiCoP and NiCoP-V P EPR analysis was performed to verify the actual existence of phosphorus vacancies, such as Figure 2 As shown, compared to NiCoP, NiCoP-V P A strong peak is observed at g value 2.003, and this signal originates from NiCoP-V. P The unpaired electrons trapped by phosphorus vacancies on the surface allow for the determination of NiCoP-V. P Phosphorus vacancies are generated, and their presence can regulate the electronic structure of the material surface, causing electron enrichment on Co, Ni, and P atoms, thereby achieving selective enrichment of nitroimidazole antibiotics.

[0027] Evaluation of NiCoP-V by metronidazole removal rateP / NF cathode materials exhibit electro-Fenton-like degradation properties, such as Figure 3 As shown, NiCoP-V P The cathode material can achieve 100% degradation of metronidazole in 30 minutes, which shows superior degradation ability compared to other cathode materials.

[0028] Depend on Figure 4 (a) shows the EPR test results with different scavenging agents added. It can be seen that a six-fold signal peak belonging to DMPO-O2·⁻ is present, while peaks belonging to ·OH and ·⁻ are not observed. 1 The signal peak of O2 indicates that O2·⁻ is the dominant reactive oxygen species; Figure 4 The high-valence metal quenching experiment results in (b) show that the addition of 5 mM DMSO quenched the high-valence metal, inhibiting the degradation efficiency of metronidazole by 10%, indicating that the high-valence metal participated in the degradation of metronidazole. The presence of P vacancies can alter the electronic structure of NiCoP, generating electron-hole pairs, thereby enhancing charge transferability and accelerating the degradation of Co. 3+ / Co 2+ and Ni 3+ / Ni 2+ The redox cycle also provides more active sites for the activation of H2O2 and O2, and generates O2· - And high-valence metal oxygen reactive species. Among them, high-valence metals can participate in the oxidation process of organic matter as intermediates, and can also react with O2· - The generation of these components has a certain synergistic effect, promoting the transition from O2+ e⁻ to ·O2⁻ and from H2O2 to ·O2. − + H + + e − The two reactions occur, thereby achieving efficient degradation of metronidazole.

[0029] Figure 5 Verification of the addition of CO3 2⁻ HCO3 ⁻ Cl ⁻ NO3 ⁻ And humic acid (HA) on EF / NiCoP-V p The effect of the / NF system on the degradation of metronidazole was investigated to evaluate the system's anti-interference ability. It can be seen that HCO3... ⁻ Cl ⁻ It does not affect degradation, CO3 2⁻ NO3 ⁻ The presence of HA slightly inhibits the degradation process, indicating that the degradation system has good anti-interference ability.

[0030] Evaluation of NiCoP-V PReusability of / NF in electro-Fenton-like systems: Multiple consecutive metronidazole degradation experiments were conducted under the same conditions. For example... Figure 6 NiCoP-V shown p After five cycles of degradation, the removal rate of metronidazole remained stable at 95% for / NF, demonstrating the material's excellent stability and reusability.

[0031] Example 1 NiCoP-V transition metal catalyst mediated by phosphorus vacancies P The cathode is a 0.1 M anhydrous sodium sulfate solution, and the DSA electrode is the anode. Metronidazole is electrochemically treated using this electrode. The anode and cathode are spaced 30 mm apart and connected to a linearly adjustable DC regulated power supply via wires.

[0032] Among them, phosphorus vacancy-mediated NiCoP-V p The specific preparation method of / NF cathode material is as follows: (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm sizes and ultrasonically cleaned for 30 min in sequence with acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0033] (2) Preparation of NiCo- precursor: 0.5821 g Co(NO3)2·6H2O, 0.2908 g Ni(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water to obtain a mixed solution; then the mixed solution and the pretreated nickel foam (2 cm × 5 cm) obtained in step (1) were transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally placed in a vacuum oven and dried at 60 °C for 6 h to obtain the NiCo- precursor.

[0034] (3) Preparation of NiCoP / NF material: NaH2PO2 (0.5 g) was placed upstream of a quartz tube as a PH3 source, and the prepared NiCo- precursor was placed downstream. Under a nitrogen atmosphere, the material was calcined at 350℃ for 2 h (heating rate 5℃ / min) to achieve further phosphating and obtain NiCoP / NF material.

[0035] (4) Construction of phosphorus vacancies: The prepared NiCoP / NF material was etched in 0.05 M (100 mL 0.2 g) NaBH4 solution for 10 min to form phosphorus vacancies, thus obtaining phosphorus vacancy-mediated NiCoP-V p / NF cathode material. (From) Figure 1It can be seen that phosphating and etching did not destroy the original needle-like morphology, but the needle-like surface formed pores with a diameter of 5~10 nm, which made the surface rougher and provided more active sites to improve the catalytic reaction.

[0036] The specific metronidazole treatment process steps are as follows: After the power is turned on, the current density stabilizes at 20 mA cm⁻¹. -2 The pH was set at 5.96, the temperature stabilized at 30℃, and the initial pollutant concentration was 10 mg / L before the stirrer was turned on. The degradation process lasted for 30 min, during which 1 mL samples were taken at 0, 2, 5, 10, 15, 20, and 30 min. All water samples were filtered through a 0.22 μm filter, and the degradation efficiency of metronidazole was subsequently evaluated by high-performance liquid chromatography (HPLC).

[0037] As determined, the removal rate of metronidazole in this embodiment reached 100% within 30 minutes (e.g., Figure 3 ).like Figure 5 As shown, phosphorus vacancy-mediated NiCoP-V p Catalysts commonly coexist with anions (CO3) in water bodies 2 Even in the presence of HCO3-, Cl-, NO3- and humic acid (HA), the removal rate of metronidazole can still reach over 90%. Furthermore, due to... Figure 6 It can be seen that after running the cycle repeatedly for 5 times under the same conditions (after treating metronidazole wastewater, the cathode is cleaned with anhydrous ethanol and deionized water before treating the next batch of wastewater, and this cycle is repeated 5 times), the removal rate of metronidazole can still reach 95%, and Ni 2+ Co 3+ The leaching concentrations were all significantly lower than those in the "Environmental Quality Standard for Surface Water in China" (GB3838-2002) and the "Integrated Wastewater Discharge Standard" (GB 8978-1996). This indicates that the method of the present invention effectively degrades metronidazole, and exhibits stable degradation performance in terms of anti-interference and stability, resulting in stable effluent quality.

[0038] Example 2 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the current density in the processing steps is 10 mA cm⁻¹. -2 After the reaction is complete, samples are taken to determine the metronidazole content.

[0039] The determination showed that the removal rate of metronidazole in this example was 100% within 30 minutes. This degradation efficiency is very high, indicating that the cathode material can effectively degrade metronidazole even at low current densities.

[0040] Example 3 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the current density in the processing steps is 40 mA cm⁻¹. -2 After the reaction is complete, samples are taken to determine the metronidazole content.

[0041] The measurement showed that the removal rate of metronidazole in this embodiment was 100% within 30 minutes. This high removal rate indicates that the cathode material effectively degrades metronidazole and has stable degradation performance, allowing for stable operation.

[0042] Example 4 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the initial pollutant concentration in the treatment process is 40 mg / L, and the metronidazole content is measured after the reaction is completed.

[0043] The test results showed that metronidazole could still be completely degraded within 30 minutes in this embodiment, indicating that the cathode material can still effectively degrade metronidazole even when the initial pollutant concentration is high.

[0044] Example 5 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the initial pollutant concentration in the treatment process is 20 mg / L, and the metronidazole content is measured after the reaction is completed.

[0045] The measurement showed that the removal rate of metronidazole in this embodiment was 100% within 30 minutes. This high removal rate indicates that the cathode material can still effectively degrade metronidazole even when the initial pollutant concentration is increased, and the degradation performance is stable, allowing for stable operation.

[0046] Example 6 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the pH is 3 in the processing steps, and the metronidazole content is measured after the reaction is completed.

[0047] Depend on Figure 7 As can be seen, the metronidazole removal rate in this embodiment is 100% within 30 minutes, indicating that the degradation of metronidazole can still be effectively achieved when the pH of the degradation medium is reduced, and the degradation performance is stable and can operate stably.

[0048] Example 7 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is the same as in Example 1, except that the pH is 12 in the processing steps, and the metronidazole content is measured after the reaction is completed.

[0049] Depend on Figure 7 It can be seen that the metronidazole removal rate in this embodiment decreased slightly to 91% within 30 minutes, indicating that the cathode material can still effectively degrade metronidazole under alkaline conditions, and the degradation performance is stable, allowing for stable operation.

[0050] Example 8 This embodiment uses the phosphorus vacancy-mediated transition metal-based cathode catalyst NiCoP-V P The method for degrading metronidazole is as described in Example 1, except that the effects of the presence of various anions and humic acid (HA) in the actual water body on the degradation process were also investigated in the treatment process steps.

[0051] Depend on Figure 5 It can be seen that adding CO3 2⁻ HCO3 ⁻ Cl ⁻ NO3 ⁻ and HA for EF / NiCoP-V P The / NF system only slightly affects the degradation of metronidazole, indicating that the system has good anti-interference ability.

[0052] Comparative Example 1 The overall process of this comparative example is the same as in Example 1, except that NiCoO is used as the cathode material to carry out the electrocatalytic degradation of metronidazole.

[0053] (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm size, and is ultrasonically cleaned for 30 min in acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water respectively to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0054] (2) Preparation of NiCo-precursor: 0.5821 g Co(NO3)2·6H2O, 0.2908 g Ni(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water. The mixed solution and a clean piece of nickel foam (2 cm × 5 cm) were then transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally dried in a vacuum oven at 60 °C for 6 h.

[0055] (3) Preparation of NiCoO / NF: NiCoO / NF cathode material was prepared by calcining at 350℃ for 2 h under nitrogen atmosphere (heating rate 5℃ / min).

[0056] The determination showed that the removal rate of metronidazole by the NiCoO / NF cathode material in this comparative example was 54% after 30 min (e.g., Figure 3 As shown in the figure, the removal rate of metronidazole decreased and the degradation rate slowed down. From the above data comparison, it can be seen that phosphorus vacancy-mediated NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance.

[0057] Comparative Example 2 The overall process of this comparative example is the same as in Example 1, except that NiCoP is used as the cathode material to carry out the electrocatalytic degradation of metronidazole.

[0058] (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm size, and is ultrasonically cleaned for 30 min in acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water respectively to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0059] (2) Preparation of NiCo-precursor: 0.5821 g Co(NO3)2·6H2O, 0.2908 g Ni(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water. The mixed solution and a clean piece of nickel foam (2 cm × 5 cm) were then transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally dried in a vacuum oven at 60 °C for 6 h.

[0060] (3) Preparation of NiCoP / NF material: NaH2PO2 (0.5 g) was placed upstream of a quartz tube as a PH3 source, and the prepared NiCo- precursor was placed downstream. Under a nitrogen atmosphere, the material was calcined at 350℃ for 2 h (heating rate 5℃ / min) to achieve further phosphating and obtain NiCoP / NF material.

[0061] The removal rate of metronidazole by NiCoP in this comparative example was determined to be 84% after 30 minutes (e.g., ...). Figure 3 As shown in the figure, the removal rate of metronidazole decreased and the degradation rate slowed down. From the above data comparison, it can be seen that phosphorus vacancy-mediated NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance.

[0062] Comparative Example 3 The overall process of this comparative example is the same as in Example 1, except that it uses NiP-V p As a cathode material, it was used in experiments to electrocatalytically degrade metronidazole.

[0063] (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm size, and is ultrasonically cleaned for 30 min in acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water respectively to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0064] (2) Preparation of Ni-precursor: 0.2908 g Ni(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water. The mixed solution and a clean piece of nickel foam (2 cm × 5 cm) were then transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally dried in a vacuum oven at 60 °C for 6 h.

[0065] (3) Preparation of NiP / NF material: NaH2PO2 (0.5 g) was placed upstream of a quartz tube as a PH3 source, and the prepared Ni- precursor was placed downstream. Under a nitrogen atmosphere, the material was calcined at 350 °C for 2 h (heating rate 5 °C / min) to achieve further phosphating and obtain NiP / NF material.

[0066] (4) Construction of phosphorus vacancies: The prepared NiP / NF material was etched in 0.05 M (100 mL 0.2 g) NaBH4 solution for 10 min to form phosphorus vacancies, thus obtaining phosphorus vacancy-mediated NiP-V p / NF cathode material.

[0067] According to the measurements, the NiP-V ratio in this comparative example reached 30 min. p The removal rate of metronidazole was only 58% (e.g. Figure 3 As shown in the figure, the removal rate of metronidazole decreased significantly and the degradation rate slowed down. From the above data comparison, it can be seen that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance.

[0068] Comparative Example 4 The overall process of this comparative example is the same as in Example 1, except that it uses CoP-V p As a cathode material, it was used in experiments to electrocatalytically degrade metronidazole.

[0069] (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm sizes and ultrasonically cleaned for 30 min in sequence with acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0070] (2) Preparation of Co- precursor: 0.5821 g Co(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water to obtain a mixed solution; then the mixed solution and the pretreated nickel foam (2 cm × 5 cm) obtained in step (1) were transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally placed in a vacuum oven and dried at 60 °C for 6 h to obtain the Co- precursor.

[0071] (3) Preparation of CoP / NF material: NaH2PO2 (0.5 g) was placed upstream of a quartz tube as a pH3 source, and the prepared Co- precursor was placed downstream. Under a nitrogen atmosphere, the material was calcined at 350 °C for 2 h (heating rate 5 °C / min) to achieve further phosphating and obtain CoP / NF material.

[0072] (4) Construction of phosphorus vacancies: The prepared CoP / NF material was etched in 0.05 M (100 mL 0.2 g) NaBH4 solution for 10 min to form phosphorus vacancies, thus obtaining phosphorus vacancy-mediated CoP-V p / NF cathode material.

[0073] The CoP-V in this comparative example was measured at 30 min. p The removal rate of metronidazole was 95% (e.g. Figure 3 As shown in the figure, the removal rate of metronidazole decreased and the degradation rate slowed down. From the above data comparison, it can be seen that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance.

[0074] Comparative Example 5 The overall process of this comparative example is the same as in Example 1, except that it uses NiCoO-V O As a cathode material, it was used in experiments to electrocatalytically degrade metronidazole.

[0075] (1) Pretreatment of cathode nickel foam substrate: The purchased nickel foam is cut into 2 cm × 5 cm size, and is ultrasonically cleaned for 30 min in acetone, hydrochloric acid (3 mmol / L), ethanol and deionized water respectively to remove surface grease and impurities. Then, it is soaked in deionized water for later use.

[0076] (2) Preparation of NiCo-precursor: 0.5821 g Co(NO3)2·6H2O, 0.2908 g Ni(NO3)2·6H2O, 0.5405 g urea and 0.1111 g NH4F were dissolved in 30 mL of deionized water. The mixed solution and a clean piece of nickel foam (2 cm × 5 cm) were then transferred to a 50 mL stainless steel autoclave and heated at 120 °C for 6 h. After the reaction was completed, the mixture was rinsed alternately with ethanol and deionized water, and finally dried in a vacuum oven at 60 °C for 6 h.

[0077] (3) NiCoO-V O Preparation of / NF: NiCoO-V was prepared by calcination at 500℃ for 2 h under nitrogen protection (heating rate 5℃ / min). O / NF cathode material.

[0078] According to measurements, the NiCoO-V ratio in this comparative example reached 30 min. O The removal rate of metronidazole was only 73% (e.g. Figure 3 As shown in the figure, the removal rate of metronidazole decreased and the degradation rate slowed down. Furthermore, the NiCoO-V... O The material's cycle stability. Figure 9 It can be seen that after running two cycles under the same conditions (treating metronidazole wastewater, cleaning the cathode with anhydrous ethanol and deionized water, and then treating the next batch of wastewater), the removal rate of metronidazole was only 12%, indicating that the material has very poor cycle stability for metronidazole degradation. The above data comparison shows that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance and stability.

[0079] Comparative Example 6 The overall process of this comparative example is the same as in Example 1, except that chloramphenicol is used as the pollutant for electrocatalytic degradation experiments.

[0080] Depend on Figure 8 It can be seen that in this comparative example, NiCoP-V at 30 min... P The removal rate of chloramphenicol was only 80%. The above data comparison shows that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance for metronidazole.

[0081] Comparative Example 7 The overall process of this comparative example is the same as in Example 1, except that bisphenol A is used as the pollutant for electrocatalytic degradation experiments.

[0082] Depend on Figure 8It can be seen that in this comparative example, NiCoP-V at 30 min... P The removal rate of bisphenol A was only 34%. The above data comparison shows that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance for metronidazole.

[0083] Comparative Example 8 The overall process of this comparative example is the same as in Example 1, except that sulfadiazine is used as the pollutant in the electrocatalytic degradation experiment.

[0084] Depend on Figure 8 It can be seen that in this comparative example, NiCoP-V at 30 min... P The removal rate of sulfadiazine was only 30%. The above data comparison shows that phosphorus vacancy-mediated bimetallic NiCoP-V... p The catalyst exhibits superior electrocatalytic degradation performance for metronidazole.

[0085] The degradation results from Examples 1 and Comparative Examples 6-8 demonstrate that the method of the present invention exhibits a significant and specific degradation effect on metronidazole. Under otherwise identical conditions, 100% degradation of metronidazole can be achieved within 30 minutes, indicating its high specificity.

[0086] In summary, the NiCoP-V based on phosphorus vacancy mediation in this invention... p The constructed electro-Fenton-like system selectively and efficiently degrades nitrosamine-containing antibiotics, achieving complete degradation of metronidazole within 30 minutes. This effect is superior to that of NiCoO, NiCoP, and NiP-V. p CoP-V p and NiCoO-V o Five materials are used, exhibiting good cycle stability and adaptability to various pollutant treatment environments (pollutant concentration, current density, pH). Compatible with NiCoO, NiCoP, and NiP-V. p CoP-V p and NiCoO-V o In comparison, firstly, the presence of phosphorus vacancies can optimize the morphology of the material, resulting in a nanoneedle-like morphology with nanoscale pores on the surface, which can expose more active sites and promote the adsorption and activation of H2O2 and O2. Secondly, the dual synergistic effect of bimetal and phosphorus vacancies can optimize the intrinsic electronic structure of the material, promote electron transfer, and optimize the adsorption and activation pathways of O2 and H2O2. Finally, the phosphorus vacancy-mediated bimetallic catalyst can simultaneously generate superoxide radicals and high-valence metal oxygen. Through synergistic effects such as electron transfer, complementary active sites, and optimized reaction pathways, the two significantly improve the catalytic efficiency and selectivity for metronidazole.

[0087] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. The application of a phosphorus vacancy-mediated transition metal-based cathode material in the selective degradation of metronidazole antibiotics using an electro-Fenton-like method, characterized in that, The phosphorus vacancy-mediated transition metal-based cathode material is NiCoP-V. p Using nickel foam as a substrate, a NiCoP catalyst containing phosphorus vacancies is loaded on the surface of the substrate; the NiCoP catalyst containing phosphorus vacancies is in the form of nanoneedles and has pores on its surface.

2. The application according to claim 1, characterized in that, The phosphorus vacancy-mediated transition metal-based cathode material was prepared by the following method: A mixed solution of nickel source, cobalt source, urea, and NH4F is provided; The substrate electrode is immersed in the mixed solution to carry out a hydrothermal reaction, thereby obtaining a substrate electrode loaded with a nickel-cobalt precursor. In an inert atmosphere, a substrate electrode loaded with nickel-cobalt precursor is placed in a tube furnace, and a phosphorus source is placed upstream of a quartz tube in the tube furnace. The electrode is heated and calcined to perform phosphating treatment, thereby obtaining a substrate electrode loaded with nickel-cobalt phosphide. The substrate electrode loaded with nickel-cobalt phosphide is placed in an etching solution for etching and reduction treatment to obtain the phosphorus vacancy-mediated transition metal-based cathode material.

3. The application according to claim 2, characterized in that, The nickel source is selected from one or more of Ni(NO3)2·6H2O, Ni(NO3)2·9H2O and NiCl2·4H2O; The cobalt source is selected from one or more of Co(NO3)2·6H2O, CoSO4·7H2O and CoCl2·6H2O; The molar ratio of the cobalt source, nickel source, urea, and NH4F is 2:1:(6~9):(2~5).

4. The application according to claim 2, characterized in that, The hydrothermal reaction temperature is 100~120℃, and the reaction time is 6~8 h.

5. The application according to claim 2, characterized in that, Inert gases in an inert atmosphere include nitrogen and / or argon; The phosphorus source is selected from one or more of NaH2PO2, NaH2PO2·H2O and Ca(H2PO2)2; The amount of phosphorus source depends on the surface area of ​​the nickel-cobalt precursor, and the amount of phosphorus source used ranges from 0.0004 g / cm³. 2 -0.0006 g / cm 2 .

6. The application according to claim 2, characterized in that, The heating rate for calcination is 2~10℃ / min, the calcination temperature is 300~500℃, and the calcination time is 2~3 h.

7. The application according to claim 2, characterized in that, The etching solution includes a NaBH4 solution with a concentration of 0.01~0.10 M and an etching-reduction time of 2~15 min.

8. The application according to claim 1, characterized in that, The concentration of metronidazole antibiotics in the wastewater is 10~40 mg / L; The pH of wastewater from metronidazole antibiotics is 3-12; During the electro-Fenton degradation treatment, the external power supply is a DC power supply, and the current density is controlled between 10 and 40 mA / cm². 2 .

9. The application according to claim 1, characterized in that, The diameter of the pore is 5~10 nm.

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