Preparation method of cathode material for electrocatalytic degradation of tetracycline and application thereof

Abstract

The application belongs to the technical field of tetracycline degradation, and discloses a preparation method of a cathode material for electrocatalytic degradation of tetracycline and application thereof, and solves the technical problems of poor tetracycline degradation effect, short service life of the catalyst and difficulty in reuse of the powdery catalyst in the prior art. The preparation method of the cathode material for electrocatalytic degradation of tetracycline comprises the following steps: configuring a solution containing soluble nickel salt, soluble iron salt and urea; loading the solution and a porous carrier into a reaction kettle for heat treatment; cleaning and drying the porous carrier after heat treatment to obtain a precursor; and performing annealing treatment on the precursor to obtain the cathode material for electrocatalytic degradation of tetracycline. The preparation method of the cathode material for electrocatalytic degradation of tetracycline has simple process, low cost and easy industrial production, and the obtained cathode material is convenient to use and regenerate, has long service life, can efficiently catalyze and activate PMS in an electrochemical environment, and improves the degradation efficiency of tetracycline.

Description

Technical Field

[0001] This invention relates to the technical field of tetracycline degradation, and more specifically, to a method for preparing cathode materials for electrocatalytic degradation of tetracycline and their applications. Background Technology

[0002] Tetracycline is one of the most widely used antibiotics in the world, used to treat respiratory infections, urinary tract infections, and sexually transmitted diseases. Its overuse in medications and personal care products has led to its presence in aquatic environments, food, and other samples. However, large amounts of tetracycline remaining in aquatic environments can seriously harm the ecological balance of water bodies and human health, making the removal of this type of antibiotic crucial. Common removal methods include physical, chemical, and biological methods, such as ultrafiltration, activated carbon adsorption, and microbial treatment. However, these methods suffer from drawbacks such as high cost, incomplete removal, and secondary pollution.

[0003] In recent years, based on sulfate radicals (·SO4) - Advanced oxidation methods (AOPs) have gained widespread attention due to their advantages of high efficiency, safety, stable removal effect, wide applicability, and low cost. Compared with ·OH, ·SO4 - It has a longer half-life (30–40 μs), a higher redox potential (2.6–3.1 V), and a wider pH operating range (2–9). PMS is ·SO4 - The main source of pollutants is PMS, but PMS itself cannot degrade pollutants on its own. It needs to be activated to produce active substances in order to degrade pollutants.

[0004] The main activation methods for PMS include catalytic activation, ultraviolet activation, thermal activation, and ultrasonic activation. Among these, catalytic activation is considered the most promising method due to its high controllability, high efficiency, mild conditions, and ease of operation. Currently, iron-based oxides with spinel structures exhibit significant catalytic activity in PMS activation. The spinel structure, with its octahedral or tetrahedral coordination, makes spinel ferrite crystals stable and resistant to acidic, alkaline, and redox environments within a certain range. Furthermore, spinel ferrite is a typical ferromagnetic material, allowing for efficient separation and recovery using magnets.

[0005] However, due to the long reaction time and relatively low activity, the application of PMS-activated degradation of tetracycline still cannot achieve the optimal degradation effect. Furthermore, as the reaction proceeds, the reversibility of the high-valence metal on the catalyst surface to a low-valence state is poor, leading to a loss of reactivity. For example, in iron-based oxides, the Fe(II) formation process is an energy-unfavorable redox cycle, which results in thermodynamically unfavorable Fe(II) regeneration and poor recycling performance. In addition, the subsequent separation and recovery of powdered iron-based oxides still suffers from complex processes and incomplete recovery, and also poses a risk of secondary pollution. Summary of the Invention

[0006] The main objective of this invention is to provide a method for preparing a cathode material for electrocatalytic degradation of tetracycline, a cathode material for electrocatalytic degradation of tetracycline, an electrochemical catalytic degradation device for tetracycline, and an electrochemical catalytic degradation method for tetracycline, so as to solve the technical problems of poor tetracycline degradation effect, short catalyst life and difficulty in reusing powdered catalysts in the prior art.

[0007] To achieve the above objectives, the present invention first provides a method for preparing a cathode material for the electrocatalytic degradation of tetracycline, the technical solution of which is as follows:

[0008] A method for preparing a cathode material for the electrocatalytic degradation of tetracycline includes the following steps:

[0009] Prepare a solution containing soluble nickel salt, soluble iron salt, and urea;

[0010] The solution and porous support are loaded into a reaction vessel for heat treatment;

[0011] The porous carrier after heat treatment is cleaned and dried to obtain the precursor.

[0012] Annealing the precursor yields the cathode material for the electrocatalytic degradation of tetracycline.

[0013] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the molar ratio of nickel ions, iron ions and urea in the solution is 1:(1-3):(12-16).

[0014] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the solvent of the solution contains 40% to 60% ethylene glycol by volume, with the balance being deionized water.

[0015] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the porous support is a foam metal containing nickel and / or iron; the foam metal is pretreated with hydrochloric acid and anhydrous ethanol.

[0016] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the heat treatment temperature is 100-150°C and the time is 6-14 hours.

[0017] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the obtained cathode material for electrocatalytic degradation of tetracycline is regenerated by annealing.

[0018] As a further improvement to the above-mentioned method for preparing the cathode material for electrocatalytic degradation of tetracycline: the annealing treatment temperature is 250-400℃ and the time is 1-3 hours.

[0019] To achieve the above objectives, the present invention further provides a cathode material for the electrocatalytic degradation of tetracycline, the technical solution of which is as follows:

[0020] The cathode material for electrocatalytic degradation of tetracycline was prepared by the method described above.

[0021] To achieve the above objectives, the present invention further provides an electrochemical catalytic degradation device for tetracycline, the technical solution of which is as follows:

[0022] An electrochemical catalytic degradation device for tetracycline includes an electrolytic cell, wherein the cathode of the electrolytic cell is a cathode material for electrocatalytic degradation of tetracycline prepared by the above-described preparation method.

[0023] To achieve the above objectives, the present invention further provides an electrochemical catalytic degradation method for tetracycline, the technical solution of which is as follows:

[0024] The electrochemical catalytic degradation method for tetracycline includes the following steps: using the above-mentioned electrochemical catalytic degradation equipment to perform electrochemical catalytic degradation treatment on the water body to be treated, which contains tetracycline, electrolyte and oxidant.

[0025] As a further improvement to the above-mentioned electrochemical catalytic degradation method of tetracycline, the method also includes the following steps: using a two-electrode single-chamber electrolytic cell, with a platinum electrode as the anode, a cathode material for electrocatalytic degradation of tetracycline as the cathode, PMS as the oxidant, and Na2SO4 as the electrolyte.

[0026] As a further improvement to the above-mentioned electrochemical catalytic degradation method of tetracycline: the concentration of PMS in the water to be treated is 1–1.5 mM, the concentration of Na2SO4 is 45–55 mM, and the current density is 2–2.5 mA / cm². 2 The electrolysis temperature is 25–40℃.

[0027] The preparation method and application of the cathode material for electrocatalytic degradation of tetracycline of the present invention have the following advantages:

[0028] First, the cathode material for electrocatalytic degradation of tetracycline of the present invention achieves effective bonding between the catalytic coating and the porous support by growing a nickel-iron bimetallic catalytic coating in situ on the surface of a porous support. The catalytic coating is not easy to fall off, making it easy to quickly separate and recycle after use without causing secondary pollution.

[0029] Secondly, the presence of nickel and iron in different valence states in the nickel-iron bimetallic catalytic coating of the cathode material for the electrocatalytic degradation of tetracycline in this invention can both induce the decomposition of PMS to produce SO4. - Furthermore, the synergistic effect of the Ni(I) and Fe(II) reactions can enable the self-oxidation cycle of nickel and iron, thereby further promoting the activation of PMS, thus significantly improving the activation effect of PMS and enhancing the catalytic degradation efficiency.

[0030] Furthermore, in order to accelerate electron transfer in transition metals and promote the recycling of metal active sites, the tetracycline degradation method of the present invention introduces an electrochemical system to directly provide electrons to high-valence metals, establish a metal redox cycle, enhance the activation of PMS by the nickel-iron bimetallic catalytic coating, thereby improving the tetracycline degradation efficiency and stability.

[0031] Therefore, the preparation method of the cathode material for electrocatalytic degradation of tetracycline of the present invention is simple, low-cost, and easy to industrialize. The obtained cathode material is convenient to use, easy to regenerate, and has a long service life. It can efficiently catalyze and activate PMS in an electrochemical environment, thereby improving the degradation efficiency of tetracycline. This significantly enhances the application prospects of catalytic PMS activation for tetracycline degradation and effectively solves the technical problems of poor tetracycline degradation effect, short catalyst life, and difficulty in reusing powdered catalysts in the prior art. It has strong practicality.

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0033] The accompanying drawings, which form part of this invention, are used to aid in understanding the invention. The content provided in the drawings and their related descriptions can be used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0034] Figure 1 This is a schematic diagram of the electrochemical catalytic degradation device for tetracycline in an embodiment of the present invention.

[0035] Figure 2 The graph shows the performance of the precursor and cathode materials at different annealing temperatures in the electrochemical catalytic degradation of tetracycline in the embodiments of the present invention.

[0036] Figure 3The graph shows the performance of the cathode material in the embodiment of the present invention at different PMS concentrations in the electrochemical catalytic degradation of tetracycline.

[0037] Figure 4 The graph shows the performance of the cathode material in the embodiments of the present invention at different current densities in the electrochemical catalytic degradation of tetracycline.

[0038] Figure 5 The diagram shows the performance of the cathode material in the embodiments of the present invention at different pH values ​​in the electrochemical catalytic degradation of tetracycline.

[0039] Figure 6 The diagram shows the performance of the cathode material in the embodiments of the present invention in the electrochemical catalytic degradation of tetracycline at different electrolysis temperatures.

[0040] Figure 7 This is a graph showing the performance of the cathode material in the electrochemical catalytic degradation of tetracycline in the presence of interfering substances in an embodiment of the present invention.

[0041] Figure 8 This is a diagram illustrating the recyclability of the cathode material in an embodiment of the present invention.

[0042] Figure 9 This is a graph showing the performance of the cathode material in the electrochemical catalytic degradation of tetracycline in actual water in the embodiments of the present invention.

[0043] Figure 10 The graphs show the performance of electrochemical catalytic degradation of tetracycline under different electrochemical systems in the embodiments of the present invention.

[0044] Figure 11 These are scanning electron microscope (SEM) images of nickel foam (ac), precursor (df), and cathode material (gf) in embodiments of the present invention.

[0045] Figure 12 The X-ray diffraction patterns of the precursor and cathode materials in this embodiment of the invention are shown.

[0046] Figure 13 The images shown are Fourier transform infrared spectra of the precursor and cathode materials in this embodiment of the invention.

[0047] Figure 14 The diagram shows the cyclic voltammetry curves of nickel foam, precursor, and cathode material in an embodiment of the present invention.

[0048] Figure 15 The electrochemical impedance spectroscopy of the nickel foam, precursor, and cathode material in this embodiment of the invention is shown. Detailed Implementation

[0049] The present invention will now be clearly and completely described in conjunction with the accompanying drawings. Those skilled in the art will be able to implement the present invention based on these descriptions. Before describing the present invention in conjunction with the accompanying drawings, it should be particularly noted that:

[0050] The technical solutions and features provided in the various parts of this invention, including the following description, can be combined with each other without conflict.

[0051] 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.

[0052] Regarding the terminology and units used in this invention: The terms "comprising," "having," and any variations thereof in the specification, claims, and related parts of this invention are intended to cover non-exclusive inclusion.

[0053] The specific implementation of the method for preparing the cathode material for electrocatalytic degradation of tetracycline of the present invention includes the following steps:

[0054] (1) Prepare a solution containing soluble nickel salt, soluble iron salt and urea;

[0055] The molar ratio of nickel ions, iron ions and urea in the solution is 1:(1-3):(12-16); in specific implementation, the molar ratio of nickel ions, iron ions and urea in the solution may be, but is not limited to, any one of 1:1:12, 1:1:14, 1:1:16, 1:2:12, 1:2:14, 1:2:16, 1:3:12, 1:3:14, and 1:3:16.

[0056] The solvent of the solution contains 40% to 60% ethylene glycol by volume, with the remainder being deionized water. Adding an appropriate amount of ethylene glycol to the solvent can fully dissolve the raw materials and improve the uniformity of the nickel-iron bimetallic catalytic coating. In specific implementation, the volume fraction of ethylene glycol in the solvent can be, but is not limited to, any one of 40%, 45%, 50%, 55%, or 60%.

[0057] (2) The solution and porous support are loaded into a reaction vessel for heat treatment;

[0058] The porous support is a foamed metal containing nickel and / or iron, which makes the porous support and the nickel-iron bimetallic catalytic coating have the same metal elements, thereby improving the bonding force between the porous support and the nickel-iron bimetallic catalytic coating.

[0059] Before use, the foam metal needs to be pretreated to remove impurities from its surface, thereby improving the synthesis efficiency. The preferred pretreatment is to first wash the foam metal with hydrochloric acid and anhydrous ethanol, then wash it with ultrapure water, and finally vacuum dry it at 50-70°C.

[0060] The porosity of the porous support is preferably ≥70%. Such a porous support has a high specific surface area, which can increase the adhesion area of ​​the nickel-iron bimetallic catalytic coating, thereby improving the catalytic effect.

[0061] The heat treatment temperature is 100-150℃ and the time is 6-14 hours; in specific implementation, the heat treatment temperature can be, but is not limited to, any one of 100℃, 110℃, 120℃, 130℃, 140℃, and 150℃, and the heat treatment time can be, but is not limited to, any one of 6 hours, 8 hours, 10 hours, 12 hours, and 14 hours.

[0062] (3) Clean and dry the heat-treated porous carrier to obtain the precursor;

[0063] The cleaning process involves alternating between anhydrous ethanol and ultrapure water; the drying process is performed under vacuum at 50–70°C.

[0064] (4) Anneal the precursor to obtain the cathode material for electrocatalytic degradation of tetracycline.

[0065] The obtained cathode material for electrocatalytic degradation of tetracycline is regenerated by annealing. Preferably, the annealing parameters of the precursor and the regeneration are the same to maintain the stability of the nickel-iron bimetallic catalytic coating.

[0066] The annealing treatment is carried out at a temperature of 250–400°C for 1–3 hours. In practice, the annealing temperature can be, but is not limited to, any one of 250°C, 280°C, 300°C, 320°C, 350°C, 380°C, and 400°C, and the annealing time can be, but is not limited to, any one of 1 hour, 1.5 hours, 2 hours, 2.5 hours, and 3 hours.

[0067] The cathode material for the electrocatalytic degradation of tetracycline of the present invention is prepared by the above-described preparation method.

[0068] The specific embodiment of the electrochemical catalytic degradation device for tetracycline of the present invention includes an electrolytic cell, wherein the cathode of the electrolytic cell is a cathode material for electrocatalytic degradation of tetracycline prepared by the above-described preparation method.

[0069] The specific implementation of the electrochemical catalytic degradation method for tetracycline of the present invention includes the following steps: using the above-mentioned electrochemical catalytic degradation equipment to perform electrochemical catalytic degradation treatment on the water body to be treated, which contains tetracycline, electrolyte, and oxidant.

[0070] The oxidant is PMS, the electrolyte is Na2SO4, the concentration of PMS is 1-1.5 mM, and the concentration of Na2SO4 is 45-55 mM. In specific implementation, the concentration of PMS can be, but is not limited to, any one of 1 mM, 1.1 mM, 1.2 mM, 1.3 mM, 1.4 mM, and 1.5 mM, and the concentration of Na2SO4 can be, but is not limited to, any one of 45 mM, 47 mM, 50 mM, 53 mM, and 55 mM.

[0071] The electrochemical catalytic degradation device is a two-electrode single-chamber electrolytic cell, with a platinum electrode as the anode and a cathode material for the electrocatalytic degradation of tetracycline, and a current density of 2–2.5 mA / cm². 2 The electrolysis temperature is 25–40℃; in specific implementation, the current density can be, but is not limited to, 2 mA / cm². 2 2.1 mA / cm 2 2.2mA / cm 2 2.3mA / cm 2 2.4mA / cm 2 2.5mA / cm 2 The electrolysis temperature can be any one of the following, but is not limited to 25℃, 28℃, 30℃, 32℃, 35℃, 38℃, or 40℃.

[0072] The following specific experimental data illustrates the beneficial effects of the present invention.

[0073] Figure 1 This is a schematic diagram of the electrochemical catalytic degradation device for tetracycline in an embodiment of the present invention.

[0074] like Figure 1 As shown, the electrochemical catalytic degradation device is a two-electrode single-chamber electrolytic cell. The anode is a platinum electrode, and the cathode is a cathode material for the electrocatalytic degradation of tetracycline. Both electrodes are square-shaped, with dimensions of 2cm × 1cm, and are arranged in parallel with a distance of 2cm between them. The volume of the water to be treated is 100mL, containing tetracycline, PMS, and Na2SO4. The water to be treated is stirred at a speed of 500r / min during operation. The total electrolysis time is 60 minutes. Every 10 minutes, 1.5mL of solution is taken, and its absorbance at λ = 354nm is analyzed using a UV-Vis spectrophotometer to obtain the concentration of tetracycline.

[0075] Tetracycline removal efficiency is calculated using the following formula:

[0076] η=(1-C t / C0)×100

[0077] Where η is the tetracycline removal efficiency, C0 and C t These represent the initial tetracycline concentration and the tetracycline concentration of the sampled solution at time t, respectively.

[0078] The method for preparing the precursor in this embodiment of the invention includes the following steps:

[0079] (1) Prepare a solution containing soluble nickel salt, soluble iron salt and urea;

[0080] The molar ratio of nickel ions, iron ions and urea in the solution is 1:2:14; the solvent of the solution contains 50% ethylene glycol by volume, with the remainder being deionized water.

[0081] (2) The solution and porous support are loaded into a reaction vessel for heat treatment;

[0082] The porous carrier is nickel foam with a porosity of over 95%. The foam metal is first washed with hydrochloric acid and anhydrous ethanol, then washed with ultrapure water, and finally vacuum dried at 50-70°C. The heat treatment temperature is 120°C and the time is 10 hours.

[0083] (3) Clean and dry the heat-treated porous carrier to obtain the precursor;

[0084] The cleaning process involves alternating between anhydrous ethanol and ultrapure water; the drying process is performed under vacuum at 60°C.

[0085] Figure 2 This diagram shows the electrochemical catalytic degradation performance of tetracycline by the precursor and cathode materials at different annealing temperatures in embodiments of the present invention. The annealing time was 2 hours for all samples; during electrolysis, the PMS concentration was 1 mM, the Na₂SO₄ concentration was 50 mM, and the current density was 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0086] like Figure 2As shown, calculations revealed that without annealing, the tetracycline removal efficiency of the precursor was only 66.8% (after 60 minutes of electrolysis, the same below). With the annealing temperature gradually increasing to 300℃, the tetracycline removal efficiency reached 80.7%, indicating that annealing significantly affects the material's structural composition, increasing the number of catalytically active sites on its surface. Further increasing the annealing temperature to 400℃ resulted in a 6.1% decrease in tetracycline removal efficiency. It was observed that the surface of the nickel foam became black and thinner, which may have led to decreased conductivity, thus reducing the tetracycline removal efficiency. In the following characterization and performance test data, the annealing temperature of the cathode material was 300℃, and the time was 2 hours.

[0087] Figure 3 This diagram shows the performance of the cathode material in the embodiment of the present invention at different PMS concentrations for the electrochemical catalytic degradation of tetracycline. During electrolysis, the Na₂SO₄ concentration was 50 mM, and the current density was 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0088] like Figure 3 As shown, when the PMS concentration increased from 0.5 mM to 1 mM, the tetracycline removal efficiency increased from 71.3% to 80.7%; however, as the PMS dosage continued to increase to over 1.5 mM, the tetracycline removal efficiency slightly decreased. This may be because excessive PMS affects the removal of SO42-. - It has a certain removal effect.

[0089] Figure 4 This diagram shows the performance of the cathode material in the embodiment of the present invention at different current densities in the electrochemical catalytic degradation of tetracycline. During electrolysis, the PMS concentration was 1 mM, the Na2SO4 concentration was 50 mM, the electrolysis temperature was 25 °C, and the pH was not adjusted.

[0090] like Figure 4 As shown, when the current density is 1.5 mA / cm² 2 Increased to 2.5 mA / cm 2 At this point, the tetracycline removal efficiency increased by approximately 20%, because the electrons provided by the cathode reduced the high-valence metals on the catalytic coating surface to low-valence metals, thereby further activating the PMS to generate active free radicals. As the current density continued to increase, the removal efficiency gradually decreased.

[0091] Figure 5 This diagram shows the performance of the cathode material in the embodiment of the present invention at different pH values ​​for the electrochemical catalytic degradation of tetracycline. During electrolysis, the PMS concentration was 1 mM, the Na₂SO₄ concentration was 50 mM, and the current density was 2.5 mA / cm². 2 The electrolysis temperature is 25℃, and the pH is adjusted using sodium hydroxide and hydrochloric acid.

[0092] like Figure 5 As shown, when the pH is not adjusted (initial pH = 3.89), the cathode material exhibits the highest tetracycline removal efficiency (reaching 81%) under natural pH conditions, which is comparable to that achieved when the pH of the water to be treated is adjusted to 3.01 or 6.96. However, the tetracycline removal efficiency decreases when the pH equals 9, and further decreases to 63% when the pH equals 10.96.

[0093] Figure 6 This diagram shows the electrochemical catalytic degradation performance of the cathode material of this invention at different electrolysis temperatures. During electrolysis, the PMS concentration was 1 mM, the Na₂SO₄ concentration was 50 mM, and the current density was 2.5 mA / cm². 2 pH not adjusted.

[0094] like Figure 6 As shown, the tetracycline removal efficiency increases with increasing electrolysis temperature, but the rate of increase decreases after the temperature exceeds 25℃; higher temperatures enhance PMS activation, leading to the generation of more SO4·. - It can also promote the thermal motion of PMS, tetracycline molecules and intermediates, increasing their contact time and thus promoting the degradation of pollutants.

[0095] Figure 7 This is a performance diagram of the cathode material in the embodiment of the present invention for the electrochemical catalytic degradation of tetracycline in the presence of interfering substances. During electrolysis, the PMS concentration was 1 mM, the Na2SO4 concentration was 50 mM, and the current density was 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted; the interfering substance in the water to be treated was Cl. - NO3 - HCO3 - Or HA, at concentrations of 10 mM, 10 mM, 10 mM and 0.1 mg / mL respectively.

[0096] like Figure 7 As shown, when Cl - Or NO3 - At that time, the tetracycline removal efficiency was 80% and 82.3%, respectively. When HCO3 was added... - At that time, the tetracycline removal efficiency dropped to 78.3%, which may be due to the addition of HCO3. - Subsequently, the solution pH increased to alkaline, consistent with the results of the pH effect experiment described above. When 10 mg of HA (humic acid) was added, the tetracycline removal efficiency decreased by only 3.3%, indicating that the presence of humic acid had only a slight inhibitory effect on tetracycline removal. In summary, the cathode material in this embodiment exhibits good anti-interference performance in removing tetracycline.

[0097] Figure 8This is a performance diagram of the cathode material's recyclability in an embodiment of the present invention. Annealing and regeneration are performed before each cycle at 300°C for 2 hours. During electrolysis, the PMS concentration is 1 mM, the Na₂SO₄ concentration is 50 mM, and the current density is 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0098] like Figure 8 As shown, starting from the third cycle, the decrease in tetracycline removal efficiency significantly reduced, indicating that the cathode material of the present invention can be used for a long time through annealing regeneration. After the first cycle, the leaching concentration of iron ions was 0.025 mg / L, but in subsequent cycles, the leaching amount of iron ions was below the detection limit, further demonstrating the stability of the cathode material of the present invention.

[0099] Figure 9 This is a performance diagram of the cathode material in the electrochemical catalytic degradation of tetracycline in actual water in an embodiment of the present invention. The water to be treated was prepared using ultrapure water, Sancha Lake water, secondary effluent, and aquaculture wastewater, respectively. The PMS concentration was 1 mM, the Na2SO4 concentration was 50 mM, and the current density was 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0100] like Figure 9 As shown, the removal efficiencies of the cathode material in ultrapure water, Sancha Lake water, secondary effluent, and aquaculture wastewater were 76.3%, 75.5%, 64.5%, and 80.5%, respectively. The results indicate that the cathode material of the present invention has good removal efficiency of tetracycline in actual water bodies in the electrochemical-PMS system.

[0101] Figure 10 The figures show the performance of electrochemical catalytic degradation of tetracycline under different electrochemical systems in the embodiments of the present invention. Wherein:

[0102] System 1: The cathode is nickel foam, without PMS or cathode materials for electrocatalytic degradation of tetracycline; other parameters are: Na2SO4 concentration of 50 mM, current density of 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0103] System 2: Without using electrochemical degradation equipment and cathode material for electrocatalytic degradation of tetracycline, only PMS was added to the water to be treated at a concentration of 1 mM; other parameters were: reaction temperature 25℃, pH not adjusted.

[0104] System 3: No electrochemical degradation equipment or PMS is used; only cathode material for electrocatalytic degradation of tetracycline is added to the water to be treated. Other parameters are: reaction temperature is 25℃, and pH is not adjusted.

[0105] System 4: The cathode is nickel foam, using PMS at a concentration of 1 mM; other parameters are: Na2SO4 concentration of 50 mM, current density of 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0106] System 5: The cathode is a cathode material for the electrocatalytic degradation of tetracycline, without PMS; other parameters are: Na₂SO₄ concentration of 50 mM, current density of 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0107] System 6: No electrochemical degradation equipment is used; only PMS and cathode material for electrocatalytic degradation of tetracycline are added to the water to be treated. The PMS concentration is 1 mM. Other parameters are: reaction temperature is 25℃, and pH is not adjusted.

[0108] System 7: The cathode is a cathode material for the electrocatalytic degradation of tetracycline, using PMS at a concentration of 1 mM; other parameters are: Na₂SO₄ concentration of 50 mM, and current density of 2.5 mA / cm². 2 The electrolysis temperature was 25℃, and the pH was not adjusted.

[0109] like Figure 10 As shown, in System 1, only 23.4% of tetracycline was removed, indicating that simple electrochemical oxidation is ineffective in removing tetracycline. In System 2, the tetracycline removal efficiency reached 42.9%, indicating that PMS hydrolysis can produce active substances that catalyze the degradation of tetracycline. In System 3, the removal of tetracycline was negligible, indicating that the cathode material for electrocatalytic degradation of tetracycline itself has a weak adsorption capacity for tetracycline.

[0110] In system 4, nickel foam was used as the cathode to degrade tetracycline, and the removal efficiency reached 57.1% within 60 minutes. Compared with systems 1-2, this shows that current can promote the production of active substances in PMS.

[0111] In system 5, the tetracycline removal efficiency increased to 29.3% compared to systems 1 and 3, indicating that electrochemistry may have a certain influence on the catalytic coating.

[0112] In system 6, the tetracycline removal efficiency reached 61.8%, which, compared with systems 2-3, indicates that the catalytic coating can activate PMS to produce active substances.

[0113] In system 7, the tetracycline removal efficiency was 81.7%. Compared with system 6, this indicates that in the electrochemical environment, the catalytic coating can activate PMS to form more active free radicals. Therefore, the electrochemical environment has a significant synergistic and enhancing effect on the catalytic reaction between the catalytic coating and PMS, as well as the degradation reaction between the active substance and tetracycline.

[0114] Figure 11 These are scanning electron microscope (SEM) images of nickel foam (ac), precursor (df), and cathode material (gf) in embodiments of the present invention.

[0115] like Figure 11 As shown, nickel foam possesses a smooth, three-dimensional cross-linked structure, which facilitates electrolyte diffusion and catalyst deposition. The heat-treated nickel foam surface becomes significantly darker, uniformly covered with petal-shaped nanosheets and nanoparticles, forming an open three-dimensional network structure. The nanosheets grow vertically, with a thickness of approximately 30 nm, while the nanoparticles are encapsulated within the nanosheets, with a particle size of approximately 50 nm. Compared to the precursor, the petal-shaped nanosheet structure on the cathode material surface gradually decreases after annealing, and the nanoparticles transform into smaller nanowires (approximately 10 nm in size), increasing the surface roughness and specific surface area of ​​the nickel foam, thus providing more sites for catalytic reactions.

[0116] Figure 12 The X-ray diffraction patterns of the precursor (represented as NiFe2O4 / NF-uncalcined, the same below) and cathode material (represented as NiFe2O4 / NF-300, the same below) in the embodiments of the present invention are shown.

[0117] like Figure 12 As shown, the diffraction peaks at 43.2°, 51.8°, and 76.4° of the precursor and cathode materials correspond to the characteristic peaks of nickel foam (JCPDS No. 87-0712), while the diffraction peaks at 30.32°, 35.67°, 43.62°, 54.01°, 57.42°, and 62.94° correspond to the characteristic peaks of spinel NiFe2O4 (JCPDS No. 10-0325), indicating successful loading of NiFe2O4 onto the surface of nickel foam. No other obvious impurity peaks were found, indicating that the precursor and cathode materials have a typical spinel ferrite structure and high purity.

[0118] Figure 13 The images shown are Fourier transform infrared spectra of the precursor and cathode materials in this embodiment of the invention.

[0119] like Figure 13 As shown, at 3456cm -1 Nearby broadband and 1631cm -1 The peaks at 611 cm⁻¹ correspond to the symmetrical tensile and bending vibrations of HOH, respectively; -1 and 415cm -1 Vibrations in the metal-oxygen band were observed at 2910 cm⁻¹, corresponding to characteristic peaks in the Fe-O stretching band and Ni-O band, respectively; the asymmetric and symmetric stretching vibrations of the -CH₂ group led to the peaks at 2910 cm⁻¹. -1 and 2845cm -1The reason for the appearance of two bands at 1384cm; -1 The peak value at that point is attributed to CO tensile vibration.

[0120] Figure 14 The diagram shows the cyclic voltammetry curves of nickel foam (represented by NF, the same below), precursor, and cathode material in the embodiments of the present invention.

[0121] like Figure 14 As shown, when the scan rate is 10 mV / s, the peak reduction current response of the cathode material is about 1.8 mA, which is significantly higher than that of nickel foam and precursor. This confirms that the reduction reaction at the cathode material interface is more significant due to the increase in specific surface area and electron transfer rate.

[0122] Figure 15 The electrochemical impedance spectroscopy of the nickel foam, precursor, and cathode material in this embodiment of the invention is shown.

[0123] In an electrochemical impedance spectroscopy plot, the diameter of the semicircle corresponds to the charge transfer resistance (Rct) of the electrolyte and the electrode. For example... Figure 15 As shown, the diameter of the cathode material is much smaller than that of the nickel foam and the precursor. The Rct values ​​of the cathode material, the precursor, and the nickel foam are 5.16Ω, 6.06Ω, and 6.56Ω, respectively. The surface cathode material shows better conductivity than the precursor and nickel foam, indicating that the NiFe2O4 nanosheets reduce the interfacial resistance of the electrode surface and improve the electron transfer rate.

[0124] In this invention, scanning electron microscope (SEM) images were taken using a JEOL JSM 7800F field emission scanning electron microscope (SEM). X-ray diffraction (XRD) spectra were recorded on a Rigaku MiniFlex 600 spectrometer (Japan). Fourier transform infrared (FTIR) spectra were measured using KBr as a reference sample on a PerkinElmer Spectrum Two spectrometer (USA). The content of metal ions in the solution was detected using a Spectrum Instruments SP-3520AA atomic absorption spectrophotometer (Shanghai). The UV-Vis spectrophotometer was a Hitachi UH-4150 (Japan).

[0125] The foregoing has described the relevant content of the present invention. Those skilled in the art will be able to implement the present invention based on these descriptions. All other embodiments obtained by those skilled in the art based on the above description of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A method for preparing a cathode material for the electrocatalytic degradation of tetracycline, characterized in that: Includes the following steps: Prepare a solution containing soluble nickel salt, soluble iron salt, and urea; the molar ratio of nickel ions, iron ions, and urea in the solution is 1:(1-3):(12-16); the solvent of the solution contains 40%-60% ethylene glycol by volume, with the remainder being deionized water; The solution and porous support are loaded into a reaction vessel for heat treatment; The porous carrier after heat treatment is cleaned and dried to obtain the precursor. Annealing the precursor yields the cathode material for the electrocatalytic degradation of tetracycline.

2. The method for preparing the cathode material for electrocatalytic degradation of tetracycline as described in claim 1, characterized in that: The porous carrier is a foamed metal containing nickel and / or iron; the foamed metal is pretreated with hydrochloric acid and anhydrous ethanol.

3. The method for preparing the cathode material for electrocatalytic degradation of tetracycline as described in claim 1, characterized in that: The heat treatment is performed at a temperature of 100–150°C for 6–14 hours.

4. The method for preparing the cathode material for electrocatalytic degradation of tetracycline as described in claim 1, characterized in that: The resulting cathode material for electrocatalytic degradation of tetracycline is regenerated by annealing; and / or, the annealing treatment is performed at a temperature of 250–400°C for 1–3 hours.

5. A cathode material for the electrocatalytic degradation of tetracycline, characterized in that: It is prepared by the preparation method according to any one of claims 1-4.

6. An electrochemical catalytic degradation device for tetracycline, comprising an electrolytic cell, characterized in that: The cathode of the electrolytic cell is a cathode material for electrocatalytic degradation of tetracycline prepared by the preparation method described in claims 1-4.

7. An electrochemical catalytic degradation method for tetracycline, characterized in that: The procedure includes the following steps: using the electrochemical catalytic degradation equipment described in claim 6 to perform electrochemical catalytic degradation treatment on the water body to be treated, which contains tetracycline, electrolyte and oxidant.

8. The electrochemical catalytic degradation method of tetracycline as described in claim 7, characterized in that: The process also includes the following steps: using a two-electrode single-chamber electrolytic cell, with a platinum electrode as the anode, a cathode material for electrocatalytic degradation of tetracycline as the cathode, PMS as the oxidant, and Na2SO4 as the electrolyte.

9. The electrochemical catalytic degradation method of tetracycline as described in claim 8, characterized in that: The concentration of PMS in the water to be treated was 1–1.5 mM, and the concentration of Na₂SO₄ was 45–55 mM; the current density was 2–2.5 mA / cm². 2 The electrolysis temperature is 25–40℃.

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