Preparation method of iron-cobalt co-doped lead dioxide electrode and application of the electrode in synergistic degradation of antibiotic-containing wastewater

Abstract

The application discloses a preparation method of an iron-cobalt co-doped lead dioxide electrode and application of the electrode in synergistic degradation of antibiotic-containing wastewater, and the iron-cobalt co-doped lead dioxide electrocatalytic anode (Fe-Co-PbO2-TNAs / Ti) is prepared by taking titanium as a substrate and in-situ growing titanium dioxide nanotubes as a transition layer. The application combines anodic oxidation and cathodic reduction, and combines high-temperature calcination of a tubular furnace, to first construct TiO2 nanotube arrays (TNAs / Ti) on the surface of a titanium substrate, and then to prepare the Fe-Co-PbO2-TNAs / Ti anode by using a water bath-electrodeposition method, and to simultaneously prepare an S-doped Co3O4 cathode. The constructed anode-cathode coupling system can realize the synergistic effect of anodic oxidation and cathodic reduction, and can effectively improve the removal capacity of typical refractory organic pollutants in pharmaceutical chemical wastewater by regulating the generation of active species and the interface electron transfer process.

Description

Technical Field

[0001] This invention relates to the field of antibiotic-containing wastewater treatment technology (such as pharmaceutical and chemical wastewater, effluent from urban sewage treatment plants, etc.), specifically to a method for preparing an iron-cobalt co-doped lead dioxide electrode and its application in synergistic degradation of antibiotic-containing wastewater. Background Technology

[0002] Antibiotic-containing wastewater mainly includes pharmaceutical and chemical wastewater and effluent from municipal wastewater treatment plants. While municipal wastewater effluent typically exhibits relatively low concentrations of antibiotics and other recalcitrant trace organic pollutants, residual risks still exist, necessitating advanced treatment. Pharmaceutical and chemical wastewater, on the other hand, is generally characterized by complex composition, high pollutant concentrations, strong toxicity, and recalcitrant degradation. Quinolone antibiotics, such as ofloxacin, possess strong biological activity and environmental persistence, posing a serious threat to aquatic ecosystems and human health once introduced into water bodies. Existing wastewater treatment technologies, such as adsorption, solvent extraction, and biodegradation, while capable of removing some pollutants, generally suffer from low treatment efficiency, high energy consumption, high costs, and secondary pollution, failing to meet the treatment needs of complex pharmaceutical and chemical wastewater. To overcome these shortcomings, there is an urgent need to develop a new and highly efficient wastewater treatment technology.

[0003] This invention provides an electrocatalytic degradation technology based on the synergistic effect of Fe-Co-PbO2 / TNAs / Ti anode and S-Co3O4 / TNAs / Ti cathode. By combining the Fe-Co-PbO2 composite material with a titanium dioxide nanotube array (TNAs), the electrocatalytic degradation efficiency of the anode is significantly improved, and the electron transport performance is enhanced. Compared with traditional titanium-based electrodes, the anode material of this invention not only solves the problems of oxide film formation and catalyst layer shedding in titanium-based electrodes, but also further improves the degradation efficiency of organic pollutants such as ofloxacin through the synergistic degradation of the anode and cathode. The Fe-Co-PbO2 material of the anode has a high oxygen evolution potential and electrocatalytic activity, while the S-Co3O4 material of the cathode improves electron transport efficiency, promoting the effective removal of organic pollutants. This technological innovation not only improves the treatment efficiency but also extends the service life of the electrode, showing great application potential. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing an iron-cobalt co-doped lead dioxide electrode and its application in the synergistic degradation of antibiotic-containing wastewater. The prepared iron-cobalt co-doped lead dioxide catalytic anode (Fe-Co-PbO2-TNAs / Ti) is based on titanium as a substrate and in-situ self-grown titanium dioxide nanotubes as a transition layer. In a single-chamber electrolytic cell, a method was developed using a sulfided cobalt tetroxide electrode (S-Co3O4 / TNAs / Ti) as the cathode and Fe-Co-PbO2-TNAs / Ti as the anode to study the synergistic electrocatalytic removal of ofloxacin (OFL). The effects of initial ofloxacin concentration, current density, electrolyte concentration, and pH on OFL removal efficiency were further investigated. The prepared electrode material possesses the chemical stability and high redox properties of lead dioxide, and its electronic structure is improved by doping with metal atoms, further enhancing catalytic activity. In application, energy consumption and production costs are reduced, and secondary pollution is avoided, achieving the goals of high efficiency, low energy consumption, and environmentally friendly operation.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing an iron-cobalt co-doped lead dioxide electrode includes the following steps: Step S1: Titanium sheet pretreatment: First, the titanium sheet is physically polished and acid-base cleaned, and then a clean and rough titanium substrate is prepared by ultrasonic-assisted chemical acid etching process. Step S2: Using the titanium substrate obtained in step S1 as the anode and an inert conductive material as the cathode, constant voltage anodic oxidation is performed in an electrolyte containing phosphate and silicate, while ultrasonic assistance is used to construct a porous titanium oxide transition layer in situ on the surface of the titanium substrate. Step S3: Using the porous titanium oxide transition layer electrode obtained in step S2 as the anode and a titanium sheet of the same area as the cathode, anodic oxidation is carried out in an ethylene glycol electrolyte containing ammonium fluoride and deionized water, so that the surface of the porous titanium oxide transition layer is further grown to form a titanium dioxide nanotube array. Step S4: The electrode obtained in step S3 is placed in an acidic solution for chemical etching and then subjected to ultrasonic treatment to thin or remove the bottom barrier layer of the titanium dioxide nanotube array and improve the pore connectivity between the nanotube array and the substrate. Step S5: The electrode obtained in step S4 is placed in an argon or nitrogen atmosphere for heat treatment to form a defect-rich, highly conductive transition layer between the titanium dioxide nanotube array and the titanium substrate. Step S6: Using the electrode with a highly conductive titanium dioxide nanotube array transition layer prepared in step S5 as the anode and a titanium sheet of the same area as the cathode, a β-PbO2 layer is electrodeposited in an acidic electrodeposition solution containing lead nitrate, iron nitrate, cobalt nitrate, potassium fluoride, polytetrafluoroethylene and nitric acid, and finally Fe-Co-PbO2-TNAs / Ti anode is obtained.

[0006] Furthermore, the specific process of titanium sheet pretreatment in step S1 is as follows: First, polish the titanium plate with a grinding wheel and sandpaper. Then, clean it with sodium hydroxide solution at 15-25°C for 20-40 minutes, followed by treatment in 15-20% sulfuric acid solution at 50-60°C for 30-50 minutes. Next, clean the titanium plate with ultrapure water, ultrasonically treat it for 10-20 minutes, dry it, and then vertically immerse the titanium plate in 10-20% oxalic acid solution. Subsequently, place it in an ultrasonic cleaner and perform ultrasonic etching at 20-40°C for 18-25 minutes. After ultrasonic etching, store it in 0.8-1.5% oxalic acid solution.

[0007] Furthermore, the specific process of step S2 is as follows: Using the titanium substrate obtained in step S1 as the anode and the titanium sheet as the cathode, the substrate is immersed in an aqueous solution containing sodium silicate and sodium phosphate. Constant voltage anodizing is performed under a constant voltage of 20~60V, with ultrasonic assistance. The treatment lasts for 5~20 minutes. The reaction is stopped when a uniform grayish-white porous oxide layer is formed on the surface of the titanium substrate. The substrate is then removed, thoroughly cleaned with deionized water, and allowed to air dry naturally to obtain a titanium substrate with a porous titanium oxide transition layer on the surface.

[0008] Furthermore, the specific process of step S3 is as follows: Using the porous titanium dioxide transition layer electrode obtained in step S2 as the anode and a titanium sheet of the same area as the cathode, the electrode is placed in an ethylene glycol solution containing 0.2~1.0 wt% ammonium fluoride and 1~10 vol% ultrapure water. The electrode is anolyzed for 0.5~3 h under a constant voltage of 20~60 V, so that a titanium dioxide nanotube array is further grown on the surface of the porous titanium dioxide transition layer. After the reaction is completed, the electrode is removed, washed with deionized water, and air-dried naturally.

[0009] Furthermore, the specific process of step S4 is as follows: The titanium dioxide nanotube array electrode obtained in step S3 is vertically immersed in oxalic acid solution, dilute nitric acid solution or dilute phosphoric acid solution, and placed in an ultrasonic cleaner for chemical etching for 5-60 minutes to thin or remove the bottom barrier layer of the titanium dioxide nanotube array. After etching, it is repeatedly rinsed with deionized water and then air-dried to obtain a titanium dioxide nanotube array electrode with higher pore connectivity.

[0010] Furthermore, the specific process of step S5 is as follows: The electrode obtained in step S4 is placed in a tube furnace and heat-treated at 300-500℃ for 0.5-3 h under an argon or nitrogen atmosphere. It is then cooled to room temperature with the furnace, allowing a Ti-rich layer to form between the titanium dioxide nanotube array and the titanium substrate. 3+ A highly conductive transition layer with oxygen vacancies is formed, thereby obtaining an electrode with a highly conductive titanium dioxide nanotube array transition layer.

[0011] Furthermore, the specific process of step S6 is as follows: Using the electrode with a highly conductive titanium dioxide nanotube array transition layer prepared in step S5 as the anode, and a titanium sheet of the same area as the cathode, an acidic electrodeposition solution containing lead nitrate, iron nitrate, cobalt nitrate, potassium fluoride, polytetrafluoroethylene, and nitric acid is applied at a current density of 20–40 mA / cm². 2 A β-PbO2 layer was obtained by electrodeposition at 80~90℃ for 1~2h, and finally Fe-Co-PbO2-TNAs / Ti anode was prepared.

[0012] Further, in step S6, an electrodeposition solution for the β-PbO2 active layer is prepared by mixing 100 g / L Pb(NO3)2, 1 g / L KF·2H2O, 6 ml / L PTFE, Fe(NO3)3·9H2O, Co(NO3)2·6H2O and 1.2 ml / L HNO3, wherein the molar ratio of iron, cobalt and lead is 1~5:100.

[0013] This invention proposes an application of the iron-cobalt co-doped lead dioxide electrode prepared by the method described above in the synergistic degradation of antibiotic-containing wastewater.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) This invention combines anodic oxidation and cathodic reduction with high-temperature calcination in a tube furnace. First, a TiO2 nanotube array (TNAs / Ti) is constructed on the surface of a titanium substrate. Then, a Fe-Co-PbO2-TNAs / Ti anode is prepared using a water bath-electrodeposition method, while simultaneously preparing an S-doped Co3O4 cathode. The constructed anode-cathode coupling system achieves the synergistic effect of anodic oxidation and cathodic reduction, effectively improving the removal capacity of typical recalcitrant organic pollutants in antibiotic-containing wastewater by regulating the generation of active species and the interfacial electron transfer process. 2) The Fe-Co-PbO2-TNAs / Ti electrode prepared in this invention exhibits good crystallinity and small surface grains, with abundant active sites on the electrode surface, which is beneficial for improving the electrocatalytic oxidation capacity of the anode surface. Simultaneously, Fe and Co co-doping can improve the surface structure and electron transport characteristics of the PbO2 active layer, enhancing the generation efficiency of active species. Experimental results show that this electrode demonstrates high pollutant removal efficiency in the anode-cathode synergistic degradation system, effectively promoting COD reduction and target pollutant degradation. 3) The anode-cathode coupling system constructed in this invention can maintain good pollutant removal performance under neutral to weakly alkaline conditions. Under optimal conditions, the system exhibits higher COD removal rate and lower unit energy consumption, indicating that the method not only has good treatment effect, but also has certain economic advantages for engineering applications. Attached Figure Description

[0015] Figure 1 SEM characterization image of the highly conductive titanium dioxide nanotubes (TNAs / Ti) prepared in Example 1; Figure 2 The image shows the SEM characterization of the Fe-Co-PbO2-TNAs / Ti iron-cobalt co-doped lead dioxide anode prepared in Example 1. Figure 3 This is a diagram illustrating the effect of different current densities on the removal rates of OFL and COD in Comparative Example 1. Figure 3 (a) shows the effect of OFL removal rate. Figure 3 (b) shows the impact of COD removal rate. Figure 4 This is a graph showing the effect of different electrolyte concentrations on the removal rates of OFL and COD in Comparative Example 2. Figure 4 (a) shows the effect of OFL removal rate. Figure 4 (b) shows the impact of COD removal rate. Figure 5 This is a graph showing the effect of different pH values ​​on the removal rates of OFL and COD in Comparative Example 3. Figure 5 (a) shows the effect of OFL removal rate. Figure 5 (b) shows the impact of COD removal rate. Figure 6 This is a graph showing the effect of 10 cycles of use on the removal rates of OFL and COD in Example 1. Figure 7 The image shows the FESEM image of the catalytic anode Fe-Co-PbO2-TNAs / Ti after 10 cycles of use in Example 1. Detailed Implementation

[0016] The present invention will be further described below with reference to embodiments and accompanying drawings, but the scope of protection of the present invention is not limited to the scope described.

[0017] Example 1

[0018] Step S1: Use a 1×3 cm titanium sheet as the electrode substrate. First, polish the titanium sheet with a grinding wheel (120 mesh) and sandpaper (1200 mesh, 600 mesh). Then, clean it with sodium hydroxide solution at 20°C for 30 minutes, followed by treatment in a 20% sulfuric acid solution at 60°C for 40 minutes. Next, clean the titanium sheet with ultrapure water, ultrasonically treat it for 15 minutes, dry it, and then vertically immerse the titanium sheet in a solution of a certain concentration of oxalic acid (avoid stacking). Place it in an ultrasonic cleaner and perform ultrasonic etching at 30°C for 20 minutes. After ultrasonic etching, store it in a 1% oxalic acid solution. Step S2: Using the titanium substrate obtained in step S1 as the anode and the titanium sheet as the cathode, immerse it in an aqueous solution containing sodium silicate and sodium phosphate, and perform constant voltage anodizing treatment under a constant voltage of 50 V, with the assistance of ultrasound. After 10 min, stop the reaction when a uniform grayish-white porous oxide layer is formed on the surface of the titanium substrate. After taking it out, wash it thoroughly with deionized water and let it air dry naturally to obtain a titanium substrate with a porous titanium oxide transition layer on the surface. Step S3: Using the porous titanium dioxide transition layer electrode obtained in step S2 as the anode and a titanium sheet of the same area as the cathode, a second anodic oxidation is carried out in a solution containing 0.5 wt% ammonium fluoride and 3 vol% ultrapure water and ethylene glycol. Electrolysis is performed for 1 hour with 40V DC to form a new oxide layer between the titanium dioxide nanotube array and the titanium substrate to eliminate the influence of the fluorine-rich oxide layer and increase the adhesion and conductivity of the titanium dioxide nanotube array. Step S4: The titanium dioxide nanotube array electrode plate obtained in step S3 is vertically immersed in 0.5 wt% oxalic acid solution, ultrasonically treated at 30℃ for 15 min, then taken out and washed with deionized water until neutral, and dried to obtain a titanium dioxide nanotube array transition layer with good pore connectivity. Step S5: The titanium dioxide nanotube array electrode with transition layer obtained in step S4 is placed in a tube furnace and heat-treated at 450°C for 2 hours under argon atmosphere protection, and then naturally cooled to room temperature to form a stable, highly conductive titanium dioxide nanotube array transition layer. Step S6: Using the TNAs / Ti prepared in step S5 as the anode and a titanium sheet of the same area as the cathode, an acidic electrolyte containing 100 g / L Pb(NO3)2, 1 g / L KF·2H2O, 6 ml / L PtFE, 0.606 g / L FFe(NO3)3·9H2O, 0.437 g / L Co(NO3)2·6H2O, and 1.2 ml / L HNO3 is applied at a current density of 20 mA / cm². 2 Fe-Co-PbO2-TNAs / Ti electrodes were prepared by electrodeposition at 80℃ for 1 h.

[0019] The FESEM images of the electrode materials TNAs / Ti and Fe-Co-PbO2-TNAs / Ti prepared in this embodiment are shown below. Figure 1 and Figure 2 As shown. From Figure 1 The SEM images show that the TiO2 nanotube array exhibits a distinct porous network structure with abundant and interconnected pores, indicating that the material has a large specific surface area and good surface openness.

[0020] Figure 2 As can be seen, the Fe-Co-PbO2-TNAs / Ti electrode surface exhibits a more regular pyramidal morphology, with uniformly distributed particles and a small diameter of approximately 25 μm. This denser and more robust electrode surface indicates that the co-doping of iron and cobalt effectively improves the electrode's stability and enhances its electrochemical performance through optimized surface structure and particle size refinement.

[0021] The catalytic anode Fe-Co-PbO2-TNAs / Ti prepared in the above examples was used in an electrolytic cell to construct an anode-cathode coupling system with the S-Co3O4 / TNAs / Ti cathode to degrade OFL. The specific process is as follows: Prepare 100 mL of an ofloxacin solution with a concentration of 200 mg / L and pour it into a single-chamber electrolytic cell reactor. Immerse the sulfur-doped cobalt tetroxide cathode (S-Co3O4 / TNAs / Ti) and anode (Fe-Co-PbO2-TNAs / Ti) in the solution, with the electrodes facing each other. Connect a regulated DC power supply and set the current density to 30 mA / cm². 2 The electrolyte concentration was 0.2 mol / L, the initial pH was [value missing], and the reaction time was 180 min. Samples were taken at 0, 10, 20, 30, 60, 90, 120, 150, and 180 min. A 10 ml syringe with a 0.22 μm organic filter was used for sampling. The collected water samples were used to determine the CODcr and ofloxacin concentrations.

[0022] Comparative Example 1 Comparative Example 1 differs from Example 1 only in that the current density during the degradation of OFL and COD was changed to 10, 20, 30, 40, and 50 mA / cm². 2 The initial OFL concentration was selected as 200 mg / L, and the results are as follows: Figure 3 As shown. Among them, Figure 3 (a) shows the removal of OFL. Figure 3 (b) shows the COD removal status.

[0023] As the current density increases from 10 mA / cm 2 Increased to 40 mA / cm 2 The removal rates of OFL and COD gradually increased, indicating that appropriately increasing the current density is beneficial to enhancing the generation of active oxygen species at the anolyte and the cathodic reduction reaction process, thereby promoting the transformation and mineralization of pollutants and their intermediate products. At 180 min of reaction, 40 mA / cm²... 2 Under the specified conditions, the removal rates of OFL and COD reached 98.22% and 66.36%, respectively, demonstrating the best treatment effect. However, when the current density was further increased to 50 mA / cm², the removal efficiency decreased. 2 At that time, the removal rates of OFL and COD decreased to 63.91% and 23.83%, respectively, indicating that excessively high current density can trigger side reactions such as oxygen evolution and hydrogen evolution, reducing the effective current utilization rate and hindering the continuous degradation and deep mineralization of pollutants. However, the current density decreased from 30 mA / cm². 2 Increased to 40 mA / cm 2 The removal rate of OFL only increased by 1.78%, and the removal rate of COD only increased by 1.36%. Considering economic and energy utilization efficiency, 30 mA / cm³ was selected. 2 The optimal current density is achieved.

[0024] Comparative Example 2 Comparative Example 2 differs from Example 1 only in that the electrolyte concentration was changed to 0.05, 0.1, 0.2, and 0.4 mol / L. An initial ofloxacin concentration of 200 mg / L and the optimal current density of 30 mA / cm² from Comparative Example 1 were selected. 2 Observe the changes in OFL and COD removal rates.

[0025] from Figure 4As can be seen, within a reaction time of 180 min, the OFL and COD removal rates reached 96.44% and 65.00% respectively under the 0.2 mol / L condition, demonstrating the best treatment effect. However, when the electrolyte concentration was further increased to 0.4 mol / L, the OFL and COD removal rates decreased to 65.61% and 21.51% respectively, indicating that excessively high ionic strength reduces the active sites on the electrode surface, which may lead to enhanced side reactions and ineffective consumption of active species, hindering the continuous degradation and deep mineralization of pollutants. Therefore, considering the overall treatment effect, the more suitable electrolyte concentration for this system is 0.2 mol / L.

[0026] Comparative Example 3 The operating procedures for Comparative Example 3 were the same as those for Example 1, except that the initial pH of the solution was changed by adjusting the pH using 0.1 mol / L sodium hydroxide solution and 0.1 mol / L sulfuric acid solution. The degradation of ofloxacin was carried out for 180 min, and the removal rates of OFL and COD were measured. The results are as follows. Figure 5 As shown.

[0027] As the pH of the solution increased from 3 to 11, the system's ability to degrade and mineralize OFL gradually increased. At an initial pH of 9, after 180 min of reaction, the removal rates of OFL and COD reached 98.17% and 71.65%, respectively, which were optimal compared to other pH conditions. In contrast, at pH 3, the removal rates of OFL and COD were only 28.17% and 10.81%, respectively, indicating that acidic conditions were unfavorable for the formation of active species and the synergistic effect of the anode and cathode in the system. Therefore, pH 9 was selected as the optimal condition.

[0028] Figure 6 and Figure 7 These are the OFL and COD removal figures and the FESEM image of Fe-Co-PbO2-TNAs / Ti after 10 cycles of electrode material recycling in Example 1. Figure 6 The results show that the first OFL removal rate was 98.17%, while the tenth OFL removal rate was 83.47%, a decrease of 14.7%. The first COD removal rate was 71.65%, while the tenth COD removal rate was 59.73%, a decrease of 11.92%.

[0029] from Figure 7 It can be seen that micro-cracks appear on the electrode surface and pores appear in the pyramid structure, but the basic morphology of Fe-Co-PbO2-TNAs / Ti is still maintained. Figure 6 and Figure 7 It can be seen that Fe-Co-PbO2-TNAs / Ti has a good degradation effect on ofloxacin.

Claims

1. A method for preparing an iron-cobalt co-doped lead dioxide electrode, characterized in that... Includes the following steps: Step S1: Titanium sheet pretreatment: First, the titanium sheet is physically polished and acid-base cleaned, and then a clean and rough titanium substrate is prepared by ultrasonic-assisted chemical acid etching process. Step S2: Using the titanium substrate obtained in step S1 as the anode and an inert conductive material as the cathode, constant voltage anodic oxidation is performed in an electrolyte containing phosphate and silicate, while ultrasonic assistance is used to construct a porous titanium oxide transition layer in situ on the surface of the titanium substrate. Step S3: Using the porous titanium oxide transition layer electrode obtained in step S2 as the anode and a titanium sheet of the same area as the cathode, anodic oxidation is carried out in an ethylene glycol electrolyte containing ammonium fluoride and deionized water, so that the surface of the porous titanium oxide transition layer is further grown to form a titanium dioxide nanotube array. Step S4: The electrode obtained in step S3 is placed in an acidic solution for chemical etching and then subjected to ultrasonic treatment to thin or remove the bottom barrier layer of the titanium dioxide nanotube array and improve the pore connectivity between the nanotube array and the substrate. Step S5: The electrode obtained in step S4 is placed in an argon or nitrogen atmosphere for heat treatment to form a defect-rich, highly conductive transition layer between the titanium dioxide nanotube array and the titanium substrate. The specific process of step S5 is as follows: The electrode obtained in step S4 is placed in a tube furnace and heat-treated at 300-500℃ for 0.5-3 h under an argon or nitrogen atmosphere. It is then cooled to room temperature with the furnace, allowing a Ti-rich layer to form between the titanium dioxide nanotube array and the titanium substrate. 3+ A highly conductive transition layer with oxygen vacancies is formed, thereby obtaining an electrode with a highly conductive titanium dioxide nanotube array transition layer; Step S6: Using the electrode with a highly conductive titanium dioxide nanotube array transition layer prepared in step S5 as the anode and a titanium sheet of the same area as the cathode, a β-PbO2 layer is electrodeposited in an acidic electrodeposition solution containing lead nitrate, iron nitrate, cobalt nitrate, potassium fluoride, polytetrafluoroethylene and nitric acid, and finally Fe-Co-PbO2-TNAs / Ti anode is obtained.

2. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 1, characterized in that... The specific process of titanium sheet pretreatment in step S1 is as follows: First, polish the titanium plate with a grinding wheel and sandpaper. Then, clean it with sodium hydroxide solution at 15-25°C for 20-40 minutes, followed by treatment in 15-20% sulfuric acid solution at 50-60°C for 30-50 minutes. Next, clean the titanium plate with ultrapure water, ultrasonically treat it for 10-20 minutes, dry it, and then vertically immerse the titanium plate in 10-20% oxalic acid solution. Subsequently, place it in an ultrasonic cleaner and perform ultrasonic etching at 20-40°C for 18-25 minutes. After ultrasonic etching, store it in 0.8-1.5% oxalic acid solution.

3. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 1, characterized in that... The specific process of step S2 is as follows: Using the titanium substrate obtained in step S1 as the anode and the titanium sheet as the cathode, the substrate is immersed in an aqueous solution containing sodium silicate and sodium phosphate. Constant voltage anodizing is performed under a constant voltage of 20~60V, with ultrasonic assistance. The treatment lasts for 5~20 minutes. The reaction is stopped when a uniform grayish-white porous oxide layer is formed on the surface of the titanium substrate. The substrate is then removed, thoroughly cleaned with deionized water, and allowed to air dry naturally to obtain a titanium substrate with a porous titanium oxide transition layer on the surface.

4. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 1, characterized in that... The specific process of step S3 is as follows: Using the electrode plate with a porous titanium oxide transition layer prepared in step S2 as the anode and a titanium sheet of the same area as the cathode, the electrode is placed in an ethylene glycol solution containing 0.2~1.0 wt% ammonium fluoride and 1~10 vol% ultrapure water. The electrode is anolyzed for 0.5~3 h under a constant voltage of 20~60 V to further grow a titanium dioxide nanotube array on the surface of the porous titanium oxide transition layer. After the reaction is completed, the electrode is removed, washed with deionized water, and air-dried naturally.

5. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 1, characterized in that... The specific process of step S4 is as follows: The titanium dioxide nanotube array electrode obtained in step S3 is vertically immersed in oxalic acid solution, dilute nitric acid solution or dilute phosphoric acid solution, and placed in an ultrasonic cleaner for chemical etching for 5-60 minutes to thin or remove the bottom barrier layer of the titanium dioxide nanotube array. After etching, it is repeatedly rinsed with deionized water and then air-dried to obtain a titanium dioxide nanotube array electrode with higher pore connectivity.

6. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 1, characterized in that... The specific process of step S6 is as follows: Using the electrode with a highly conductive titanium dioxide nanotube array transition layer prepared in step S5 as the anode, and a titanium sheet of the same area as the cathode, an acidic electrodeposition solution containing lead nitrate, iron nitrate, cobalt nitrate, potassium fluoride, polytetrafluoroethylene, and nitric acid is applied at a current density of 20–40 mA / cm². 2 A β-PbO2 layer was obtained by electrodeposition at 80~90℃ for 1~2h, and finally Fe-Co-PbO2-TNAs / Ti anode was prepared.

7. The method for preparing an iron-cobalt co-doped lead dioxide electrode according to claim 6, characterized in that... In step S6, a β-PbO2 active layer electrodeposition solution is prepared by mixing 100 g / L Pb(NO3)2, 1 g / L KF·2H2O, 6 ml / L PTFE, Fe(NO3)3·9H2O, Co(NO3)2·6H2O and 1.2 ml / L HNO3, wherein the molar ratio of iron, cobalt and lead is 1~5:

100.

8. The application of an iron-cobalt co-doped lead dioxide electrode prepared according to any one of claims 1-7 in the synergistic degradation of antibiotic-containing wastewater.

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