A method for removing perfluorinated compounds from wastewater

Abstract

The present application relates to wastewater treatment technical field, disclose a kind of methods for removing perfluorinated compounds in wastewater, method includes the following steps: preparation reaction mother liquor: adding magnetic response inert high-hardness micron-sized particles to the wastewater containing perfluorinated compounds, and adjusting the pH value of wastewater to alkaline range, mix uniformly.Construction reaction system: reaction mother liquor is introduced into electrolytic cell, three-dimensional porous anode and cathode are arranged in the electrolytic cell, wherein anode surface is loaded with ruthenium iridium titanium metal oxide active coating.Pulse electrolysis degradation: apply pulse direct current field, nanobubble is generated on anode, and chain cavitation is induced by inert particle, thereby forming local high temperature and high pressure environment in micro region, and then generating hydroxyl radical in situ to degrade perfluorinated compounds.The present application utilizes three-dimensional porous anode, pulse electric field and inert particle to synergistically induce chain cavitation, efficiently generates hydroxyl radical, realizes the efficient degradation and complete mineralization to perfluorinated compounds.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for removing perfluorinated compounds from wastewater. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) are a class of man-made organic compounds with carbon-fluorine (CF) bonds as their main structure. The high bond energy of these CF bonds endows these substances with excellent chemical and thermal stability, leading to their widespread use in industrial production and everyday consumer products. However, precisely because of the chemical inertness of the CF bonds, PFAS are extremely difficult to degrade in the natural environment, exhibiting high persistence, bioaccumulation, and potential ecological and health risks. Therefore, developing technologies that can efficiently and completely remove PFAS from water bodies has become an important issue in the field of environmental remediation.

[0003] Among numerous technologies for treating persistent organic pollutants (POPs), advanced oxidation technologies (AOPs), particularly electrochemical oxidation, have shown great application potential due to their environmental friendliness, lack of the need for external chemical reagents, and ease of automation. The basic principle of this method is to generate hydroxyl radicals (·OH) with extremely high oxidation potential in situ on the anode surface of an electrolytic cell by electrolyzing water molecules or hydroxide ions. These highly oxidizing species are then used to degrade pollutants in the water.

[0004] Although electrochemical oxidation is theoretically feasible, existing technologies still have the following shortcomings when treating recalcitrant substances such as PFAS:

[0005] First, the reaction efficiency is limited by the mass transfer process at the solid-liquid interface. The generation of hydroxyl radicals is confined to the extremely thin diffusion layer on the anode surface, while PFAS molecules in the bulk phase must diffuse to reach this reaction region, resulting in a low overall reaction rate.

[0006] Secondly, complete mineralization is difficult to achieve. The complete breaking of CF bonds in PFAS molecules requires extremely high energy input. The reaction environment generated by traditional electrochemical oxidation is insufficient in terms of energy density and oxidizing power to ensure the effective breaking of all CF bonds. This often leads to degradation stopping at short-chain perfluorinated compounds and other intermediate products that are still biologically toxic, posing a risk of secondary pollution.

[0007] Third, energy utilization efficiency is low. To increase the degradation rate, a higher anodic potential is usually required, but this will exacerbate the oxygen evolution reaction (OER). This side reaction competes with the generation of hydroxyl radicals and consumes a large amount of current, thereby reducing the overall current efficiency and the energy consumption per unit of pollutant removal. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a method for removing perfluorinated compounds from wastewater, solving the problems of low degradation efficiency, incomplete mineralization, and high energy consumption in existing electrochemical oxidation methods for treating wastewater containing perfluorinated compounds.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a method for removing perfluorinated compounds from wastewater, the method comprising the following steps:

[0010] S1. Preparation of the reaction mother liquor: Take wastewater containing perfluorinated compounds and add magnetically responsive, inert, high-hardness micron-sized particles to the wastewater. Use an acid-base adjuster to adjust the pH of the wastewater to an alkaline range of 9-12. Stir the mixed liquid until the particles form a uniform suspension in the liquid to obtain the reaction mother liquor.

[0011] In one specific embodiment, the dosage of the magnetically responsive inert high-hardness micron-sized particles is 0.5-5 g / L, and the particle size is 1-10 micrometers. The material of the particles is selected from magnetite micron-sized particles or a core-shell structured magnetic composite particle. The core-shell structured magnetic composite particle has a magnetic material core and an inert high-hardness ceramic shell covering the surface of the core.

[0012] S2. Preparation of the electrolytic reaction: The reaction mother liquor prepared in step S1 is introduced into an electrolytic cell. The electrolytic cell is equipped with a cathode and a three-dimensional porous anode. Both the inner and outer surfaces of the three-dimensional porous anode are loaded with an active coating of ruthenium-iridium-titanium metal oxide.

[0013] In one specific embodiment, the structure of the three-dimensional porous anode includes a three-dimensional porous substrate and an active coating loaded on the substrate. The substrate is made of titanium foam or carbon felt. The fabrication process of the three-dimensional porous anode is as follows: first, the three-dimensional porous substrate is pretreated by chemical etching; then, a coating solution containing ruthenium precursor salt and iridium precursor salt is applied to the pretreated substrate by dip-coating or brush coating; finally, the coated substrate is subjected to high-temperature annealing to decompose the precursor salt, thereby forming the ruthenium-iridium-titanium metal oxide active coating on the inner and outer surfaces of the substrate.

[0014] S3, Pulsed Electrolytic Degradation: A pulsed DC electric field is applied between the three-dimensional porous anode and the cathode. By setting the pulse frequency and duty cycle, the electric field is periodically switched between a high-potential energizing phase and a low-potential or zero-potential turning-off phase.

[0015] The duty cycle is determined and controlled by the following formula:

[0016]

[0017] In the formula, γ is the duty cycle; t on The duration of the high-potential energizing phase within a single pulse cycle is T; the pulse cycle is T.

[0018] During the high-potential energizing phase, water electrolysis occurs on the large specific surface area of ​​the three-dimensional porous anode, generating a large number of nanobubbles. Magnetically responsive, inert, high-hardness micron-sized particles suspended in the reaction mother liquor provide a heterogeneous nucleation surface for these newly formed nanobubbles, promoting their enrichment within the anode pore structure.

[0019] During the low-potential or zero-potential turn-off phase, the nanobubbles, deprived of electric field support, become unstable. At this time, the hard surface of the magnetically responsive, inert, high-hardness micron-sized particles and their movement in the liquid induce and trigger the collapse of nearby unstable nanobubbles. The collapse of a single bubble generates a micro-shock wave, which then triggers a chain reaction of coordinated collapse of other nearby bubbles—this is the chain cavitation effect.

[0020] This chain cavitation effect can instantaneously create a localized high-temperature, high-pressure environment within a microscopic region, sufficient to cause the pyrolysis of water molecules, thereby generating a large number of hydroxyl radicals in situ within the bulk phase of the mother liquor. These generated hydroxyl radicals possess extremely high oxidation potentials, enabling them to efficiently oxidize and degrade perfluorinated compound molecules present in the mother liquor. In a preferred embodiment, the perfluorinated compound is perfluorooctane sulfonic acid, which is ultimately mineralized into carbon dioxide and fluoride ions.

[0021] During electrolysis, a water reduction reaction (2H₂O + 2e⁻) simultaneously occurs at the cathode. - →H₂↑+2OH - The process generates hydrogen gas and hydroxide ions. Hydrogen generation requires the electrolytic cell to have a safe venting device. The generation of hydroxide ions helps maintain the overall alkaline pH environment of the reaction mother liquor, creating a synergistic effect with the anode-side reaction.

[0022] The present invention also includes a process for monitoring the degradation process. This process involves: periodically aspirating samples of the mother liquor during the degradation process, filtering the samples to remove the magnetically responsive, inert, high-hardness micron-sized particles, then analyzing the filtrate to determine the instantaneous concentration of perfluorinated compounds, and calculating the perfluorinated compound removal rate according to the following formula:

[0023]

[0024] In the formula, R PFCs C0 is the removal rate of the perfluorinated compound; C0 is the initial concentration of the perfluorinated compound; C0 is the concentration of the perfluorinated compound. t The instantaneous concentration of the perfluorinated compound at reaction time t.

[0025] Furthermore, after the perfluorinated compounds are degraded, the present invention also includes a process for recycling and reusing the magnetically responsive, inert, high-hardness micron-sized particles. This process is as follows: First, by applying an external magnetic field to the region where the mother liquor is located, the magnetically responsive, inert, high-hardness micron-sized particles are adsorbed and aggregated using magnetic force, thereby achieving separation of the solid and liquid phases; then, the separated solid particles are collected; finally, the collected particles are washed and dried, and the treated particles can be reused in new wastewater treatment processes.

[0026] This invention provides a method for removing perfluorinated compounds from wastewater. It has the following beneficial effects:

[0027] 1. This invention constructs a unique reaction system capable of inducing chain cavitation through the synergistic effect of a three-dimensional porous anode, a pulsed DC electric field, and magnetically responsive particles. This effect enables the in-situ generation of high-concentration hydroxyl radicals in the bulk phase of the reaction mother liquor, fundamentally overcoming the mass transfer bottleneck of traditional electrochemical methods that are limited to the electrode surface. Simultaneously, the physical effects of micro-shock waves accompanying chain cavitation, combined with the strong chemical oxidizing power of hydroxyl radicals, can efficiently break the extremely stable carbon-fluorine bonds in perfluorinated compounds, thereby achieving rapid and thorough degradation and mineralization of pollutants.

[0028] 2. This invention uses magnetically responsive, inert, high-hardness micron-sized particles as the physical induction medium. After the degradation reaction is complete, efficient and rapid separation and recovery of the particles from the water can be achieved simply by applying an external magnetic field. This recovery method eliminates the need for complex filtration equipment, fundamentally avoiding the problem of filter membrane clogging. Furthermore, it boasts a high particle recovery rate and extremely low loss, significantly reducing material and equipment maintenance costs, thus giving the entire process superior economic efficiency and industrial application potential.

[0029] 3. This invention employs a pulsed DC electric field instead of traditional continuous DC current. By programmatically setting the pulse duty cycle and frequency, the complete cycle of nanobubble generation, enrichment, and synergistic collapse is precisely controlled. The input electrical energy is efficiently converted via a path of electrical energy – bubble interface energy – physical impact energy, and concentratedly released at the core step of generating hydroxyl radicals. Compared to continuous electrolysis, this reduces ineffective energy loss in side reactions such as continuous oxygen evolution, improves the removal efficiency of pollutants per unit of electrical energy, and makes the entire degradation process more efficient and controllable. Attached Figure Description

[0030] Figure 1 This is a schematic diagram illustrating the generation mechanism of the chain cavitation effect in this invention.

[0031] Figure 2 This is a schematic flowchart of the method of the present invention;

[0032] Figure 3This is a schematic diagram of the process for preparing the reaction mother liquor according to the present invention;

[0033] Figure 4 This is a schematic diagram of the pulse electrolytic degradation process of the present invention. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Please see the appendix Figure 1 -Appendix Figure 4 :

[0036] Example:

[0037] Preparation of the mother liquor:

[0038] Take experimental water (deionized water) and dissolve PFOA standard in it to prepare simulated PFOA-containing wastewater with an initial concentration of 50 mg / L. Take 400 mL of this simulated wastewater and place it in a beaker. Use a pH meter to monitor the pH and add 1 mol / L sodium hydroxide (NaOH) solution dropwise to precisely adjust the pH of the wastewater to 11.

[0039] Subsequently, 2 g / L of magnetically responsive, inert, high-hardness micron-sized particles were added to the pH-adjusted wastewater. In this embodiment, the selected particles were core-shell magnetic composite particles (Fe3O4@SiO2) with a core of iron tetroxide and a shell of silicon dioxide, and an average particle size of 5 micrometers.

[0040] Finally, place the beaker on a magnetic stirrer and stir continuously at 500 rpm for 30 minutes to ensure that the magnetic composite particles are evenly dispersed in the solution and form a stable suspension of the reaction mother liquor.

[0041] Preparation of three-dimensional porous anodes and construction of electrolytic cells:

[0042] In this embodiment, titanium foam is used as the substrate for the three-dimensional porous anode. The substrate has dimensions of 50 mm × 50 mm × 2 mm, a porosity of 95%, and a pore density of 100 PPI (Pores Per Inch).

[0043] The anode preparation process is as follows:

[0044] First, the foamed titanium substrate was pretreated. The substrate was ultrasonically cleaned in acetone solution for 15 minutes to remove surface oil, and then rinsed thoroughly with deionized water. Next, it was immersed in a 10% oxalic acid solution and etched at 80°C in a water bath for 2 hours to remove the surface oxide layer and roughen the surface. Afterward, it was repeatedly rinsed with deionized water until neutral, and then dried in an 80°C oven for later use.

[0045] Next, prepare the coating solution. Accurately weigh ruthenium chloride (RuCl3·xH2O) and iridium chloride (IrCl4·xH2O) precursor salts, making the molar ratio of Ru to Ir 7:3, and dissolve them in isopropanol to prepare a homogeneous coating solution with a total metal ion concentration of 0.1 mol / L.

[0046] Then, the coating liquid was uniformly coated onto the inner and outer surfaces of the pretreated foamed titanium substrate using a brush coating method. After each coating, the substrate was placed in an oven at 80°C for 10 minutes to dry, and then transferred to a muffle furnace to be heated to 450°C at a heating rate of 5°C / min in air atmosphere and held at that temperature for 15 minutes for thermal decomposition.

[0047] Repeat the coating-drying-thermal decomposition steps 12 times until the theoretical loading of the ruthenium-iridium-titanium metal oxide active coating reaches 1.5 mg / cm².

[0048] The prepared three-dimensional porous anode and a titanium plate of the same size (as cathode) were placed parallel to each other in a 500 mL volume organic glass electrolytic cell, and the distance between the two plates was adjusted to 2 cm.

[0049] Pulse electrolysis synergistic degradation experiment:

[0050] The prepared 400 mL reaction mother liquor was completely transferred into the constructed electrolytic cell. The anode and cathode were connected to the positive and negative terminals of a programmable pulse power supply, respectively. The parameters of the pulse power supply were set as follows: peak current density 50 mA / cm², pulse frequency 1000 Hz, and duty cycle 50%. The power supply was turned on, and the reaction mother liquor was magnetically stirred at 300 rpm to maintain the suspension of the particles. The experiment was conducted at room temperature (25 °C), and the total reaction time was 120 minutes.

[0051] Sample Analysis and Performance Evaluation: At 0, 15, 30, 60, 90, and 120 minutes into the reaction, 2 mL of reaction solution was drawn from the electrolytic cell and placed into different centrifuge tubes. A strong neodymium iron boron permanent magnet was placed firmly against the outer wall of the centrifuge tube and allowed to stand for 1 minute to allow the magnetic composite particles inside the tube to be completely adsorbed and aggregated on one side of the tube wall. Subsequently, the clear liquid at the top of the tube was carefully aspirated using a pipette and injected into the sample vial through a 0.22-micron nylon needle filter to remove the magnetic composite particles.

[0052] The concentration of PFOA in the filtrate was determined using liquid chromatography-mass spectrometry (LC-MS / MS). The concentration of fluoride ions was determined using a Dionex ICS-900 ion chromatograph (IC).

[0053] PFOA removal rate is based on the formula:

[0054]

[0055] In the formula, R PFCs C0 is the removal rate of the perfluorinated compound; C0 is the initial concentration of the perfluorinated compound; C0 is the concentration of the perfluorinated compound. t The instantaneous concentration of the perfluorinated compound at reaction time t.

[0056] Recovery of magnetically responsive particles: After the 120-minute reaction, the power and stirring were turned off. A strong neodymium iron boron (NdFeB) permanent magnet was placed against one side of the outer wall of the electrolytic cell. After standing for 5 minutes, it was observed that the magnetic composite particles in the solution were adsorbed and aggregated on the cell wall near the magnet, and the main solution became clear again. The supernatant was carefully pumped out, thus achieving solid-liquid separation.

[0057] Remove the permanent magnet, rinse the particles off the pool wall with a small amount of deionized water and collect them. Rinse the collected particles repeatedly with deionized water 3-5 times to remove adsorbed ions and residual solution.

[0058] Finally, the cleaned particles were placed in an oven at 105°C and dried for 4 hours. The dried magnetic composite particles can be directly used in the next degradation experiment, achieving recycling.

[0059] Comparative Example 1:

[0060] The difference from the example is that the anode used in the electrolytic cell is replaced with a planar titanium plate-based ruthenium-iridium titanium electrode with the same projected area (50 mm × 50 mm). The preparation method and active material loading of this electrode are the same as those of the three-dimensional porous anode in the example. All other experimental conditions and operating procedures are exactly the same as those in the example.

[0061] Comparative Example 2:

[0062] The difference from the example is that the power supply during electrolysis is changed from a pulsed DC electric field to a constant DC electric field. A constant current electrolysis mode is used, with a constant current density of 25 mA / cm² (equal to the average current density of the pulsed current in the example) to ensure that the total charge input is the same in both experiments over a total reaction time of 120 minutes. All other experimental conditions and operating procedures are exactly the same as in the example.

[0063] Comparative Example 3:

[0064] The difference from the example is that, in preparing the reaction mother liquor, core-shell magnetic composite particles (Fe3O4@SiO2) with iron tetroxide as the core and silicon dioxide as the shell are not added to the wastewater. All other experimental conditions and operating procedures are exactly the same as in the example.

[0065] Test Example 1:

[0066] Experimental steps:

[0067] To evaluate the role of each key technical feature in the technical solution, the four electrolytic cell devices in the examples and comparative examples 1-3 were tested in parallel. All experiments were started simultaneously under the same ambient temperature (25°C) and atmospheric pressure conditions. At 0, 5, 15, 30, 60, and 120 minutes of reaction, 2 mL of reaction solution was simultaneously aspirated from each of the four electrolytic cells and transferred to different 2 mL centrifuge tubes.

[0068] The samples were pretreated as follows: A strong neodymium iron boron permanent magnet was placed firmly against the outer wall of the centrifuge tube and left to stand for 1 minute to allow the magnetic composite particles inside the tube to be completely adsorbed and aggregated on one side of the tube wall. Then, the clear liquid in the upper layer of the tube was carefully aspirated with a pipette and injected into the sample vial through a 0.22-micron nylon needle filter.

[0069] The processed samples were preserved, and the instantaneous concentration of PFOA in each sample was determined using liquid chromatography-mass spectrometry (LC-MS / MS). Based on the measurement results, the PFOA removal rate at each time point was calculated.

[0070] Experimental data: The PFOA removal rate data of the four experimental groups at different time points are recorded in Table 1.

[0071] Table 1: Comparison of PFOA removal rates (%) between the Examples and Comparative Examples 1-3 at different time points

[0072] Time (min) Example Comparative Example 1 Comparative Example 2 Comparative Example 3 15 95.2 25.5 40.3 15.1 30 99.1 40.1 58.6 25.4 60 99.8 51.3 69.8 35.8 90 >99.9 58.2 74.5 41.3 120 >99.9 61.5 76.8 44.2 15 95.2 25.5 40.3 15.1

[0073] From Table 1, we can obtain:

[0074] The PFOA removal rate using the technical solution in the example was higher than that using the technical solutions in Comparative Examples 1, 2, and 3 throughout the entire reaction cycle, demonstrating an overwhelming technical advantage. The removal rate of the example was as high as 95.2% at 15 minutes, and it was almost completely degraded after 30 minutes. This degradation rate far exceeded that of the comparative examples.

[0075] The data comparison between the examples and Comparative Example 1 shows that, under the same conditions, the degradation efficiency using a three-dimensional porous anode is much higher than that using a planar electrode. This is because the interconnected network structure and large specific surface area of ​​the three-dimensional porous anode provide more active sites for the water electrolysis reaction, and also provide ample physical space for the subsequent chain cavitation effect, thereby increasing the contact probability between the reactants and hydroxyl radicals and the overall reaction rate.

[0076] A comparison of the data from the examples with Comparative Example 2 reveals a significant difference in degradation efficiency between pulsed DC electric fields and constant DC electric fields. The application of a pulsed electric field enables periodic control of the nanobubble generation (energized phase) and collapse (de-energized phase) processes. This controlled cyclic process efficiently triggers the synergistic collapse of nanobubbles, thereby generating a chain cavitation effect. Under a constant DC electric field, bubbles tend to continuously grow, aggregate, and detach; the intensity and range of the physicochemical effects generated by their random collapse are limited, resulting in a lower yield of hydroxyl radicals.

[0077] The comparison of data from the examples with Comparative Example 3 demonstrates the decisive role of magnetically responsive, inert, high-hardness micron-sized particles in the system. In Comparative Example 3, which lacked these particles, the degradation rate of PFOA was the lowest. This is because the particles, acting as heterogeneous nucleation sites in the reaction mother liquor, promoted the enrichment of nanobubbles within the three-dimensional anodic channels. More importantly, as a physical triggering medium, they enhanced the transmission and superposition effects of shock waves upon the instability and collapse of nanobubbles, thereby inducing large-scale chain cavitation, which is the core of achieving rapid pollutant degradation.

[0078] Test Example 2:

[0079] Experimental steps:

[0080] To investigate the effect of the initial pH of the reaction mother liquor on the degradation efficiency of PFOA, four parallel experiments were set up. Except for the initial pH value, all other conditions were completely consistent with the example. The initial pH values ​​of the reaction mother liquor in the four experimental groups were adjusted to 7.0, 9.0, 11.0, and 13.0 by adding sodium hydroxide solution or sulfuric acid solution, respectively.

[0081] After the experiment was started, samples were simultaneously drawn from the four electrolytic cells at 0, 15, 30, 60, 90 and 120 minutes of reaction, and the samples were filtered, the concentration was measured and the removal rate was calculated in the same manner as in Test Example 1.

[0082] Experimental data: The PFOA removal rate data of the four experimental groups with different initial pH values ​​at different time points are recorded in Table 2.

[0083] Table 2: Comparison of PFOA removal rates (%) under different initial pH conditions

[0084]

[0085]

[0086] From Table 2, we can obtain:

[0087] The removal rate of PFOA was lowest under neutral conditions (pH=7.0); as the pH value entered the alkaline range, the removal rate increased significantly and reached its highest value at pH 11.0; when the pH value was further increased to 13.0, the removal rate decreased slightly compared to pH=11.0.

[0088] In this technical solution, the main sources of hydroxyl radicals are twofold: the pyrolysis of water molecules under chain cavitation effect and the electrochemical oxidation of water or hydroxide ions on the anode surface. Under alkaline conditions, the mother liquor is rich in hydroxide ions (OH-). - It can directly undergo oxidation reaction (OH) on the anode surface. - →·OH+e - The formation of hydroxyl radicals. This process is similar to the oxidation of water at the anode (H₂O → ·OH + H₂). + +e - The parallel occurrence of these processes increases the overall yield of hydroxyl radicals, thereby accelerating the oxidative degradation of PFOA.

[0089] However, when the pH value is too high (e.g., pH = 13.0), although the concentration of hydroxide ions is higher, an oxygen evolution reaction (4OH-) occurs on the anode surface. - →O2 + 2H2O + 4e - The competition for PFOA also increases. The oxygen evolution reaction consumes some current and anolyte active sites, thereby reducing the current efficiency used to generate hydroxyl radicals. Therefore, excessively high pH values ​​may actually lead to a slight decrease in the degradation rate of PFOA, indicating the existence of an optimal alkaline pH range within which the generation rate of hydroxyl radicals is maximized.

[0090] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for removing perfluorinated compounds from wastewater, characterized in that, The method includes the following steps: S1. Take wastewater containing perfluorinated compounds, add magnetically responsive inert high-hardness micron-sized particles to the wastewater, adjust the pH of the wastewater to alkaline, mix evenly to obtain a reaction mother liquor. The magnetically responsive inert high-hardness micron-sized particles are core-shell structured magnetic composite particles. The core-shell structured magnetic composite particles have a magnetic material core and an inert high-hardness ceramic shell covering the surface of the core. S2. The prepared reaction mother liquor is introduced into an electrolytic cell equipped with a three-dimensional porous anode and a cathode, wherein the surface of the three-dimensional porous anode is loaded with a ruthenium-iridium-titanium metal oxide active coating. S3. A pulsed DC electric field is applied between the three-dimensional porous anode and the cathode. Water in the reaction mother liquor is electrolyzed on the three-dimensional porous anode to generate nanobubbles. The generated nanobubbles are induced by magnetically responsive inert high-hardness micron-sized particles suspended in the reaction mother liquor to undergo a chain cavitation effect, thereby generating hydroxyl radicals in situ to degrade perfluorinated compounds present in the reaction mother liquor.

2. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, In step S1, the process of preparing the reaction mother liquor specifically includes: The pH of the wastewater was adjusted to the range of 9-12 using an acid-base adjuster. Add the magnetically responsive inert high-hardness micron-sized particles with a particle size of 1-10 micrometers at a dosage of 0.5-5 g / L. The magnetically responsive inert high-hardness micron-sized particles are core-shell magnetic composite particles with iron oxide as the core and silicon dioxide as the shell. The mixed liquid is stirred until the particles are uniformly suspended.

3. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, In step S2, the three-dimensional porous anode disposed in the electrolytic cell has a structure comprising a three-dimensional porous substrate made of foamed titanium or carbon felt, and an active coating of ruthenium-iridium titanium metal oxide formed by loading it onto the inner and outer surfaces of the three-dimensional porous substrate.

4. The method for removing perfluorinated compounds from wastewater according to claim 3, characterized in that, The fabrication process of the three-dimensional porous anode is as follows: The three-dimensional porous substrate is pretreated by chemical etching; A coating solution containing ruthenium and iridium precursor salts is applied to the pretreated substrate by dip-coating or brushing. The coated substrate is subjected to high-temperature annealing to decompose the precursor salt and form the active coating.

5. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, The step of applying the pulsed DC electric field includes: By setting the pulse frequency and duty cycle, the electric field is periodically switched between a high-potential energizing phase and a low-potential or zero-potential turning-off phase, thereby programmatically controlling the generation-collapse cycle of the nanobubbles.

6. The method for removing perfluorinated compounds from wastewater according to claim 5, characterized in that, The duty cycle The following formula is used for determination and control: ； In the formula, The duty cycle is mentioned; The duration of the high-potential energizing phase within a single pulse cycle; The pulse period is denoted as .

7. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, The degradation step mineralizes the perfluorinated compound into carbon dioxide and fluoride ions; the perfluorinated compound present in the mother liquor is perfluorooctane sulfonic acid.

8. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, The method also includes a process for monitoring the degradation process, which involves: periodically aspirating a sample of the mother liquor during the degradation process, filtering the sample to remove the magnetically responsive, inert, high-hardness micron-sized particles, and then analyzing the filtrate to determine the instantaneous concentration of perfluorinated compounds. The perfluorinated compound removal rate is calculated according to the following formula. : ； In the formula, The removal rate of the perfluorinated compounds; The initial concentration of the perfluorinated compound; Reaction time The instantaneous concentration of the perfluorinated compound at a given time.

9. The method for removing perfluorinated compounds from wastewater according to claim 1, characterized in that, After the perfluorinated compound is degraded, the method further includes a process for recycling and reusing the magnetically responsive, inert, high-hardness micron-sized particles, the process being as follows: First, by applying an external magnetic field to the region where the mother liquor is located, the magnetically responsive, inert, high-hardness micron-sized particles are adsorbed and aggregated, thereby achieving solid-liquid separation. Then the separated solid phase, namely the magnetically responsive, inert, high-hardness micron-sized particles, is collected. The collected particles are washed and dried for recycling.

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