Preparation method and application of electro-Fenton curtain type composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membrane

Abstract

The invention provides a preparation method and application of an electro-Fenton curtain type composite cathode assembly based on a hydrophilic / hydrophobic hollow fiber membrane, and belongs to the technical field of electrochemistry, and the preparation method comprises the following steps: respectively cutting a conductive material, a hydrophilic hollow fiber membrane and a hydrophobic hollow fiber membrane into equal lengths; sequentially placing in a pretreatment solution and deionized water for ultrasonic cleaning, and drying to obtain a pretreated conductive material, a hydrophilic membrane material and a hydrophobic membrane material; the preparation method comprises the following steps: inserting a supporting material into a conductive material to obtain a conductive material with supporting performance, then fixing the conductive material on a hydrophobic membrane material to obtain a conductive material coupled hydrophobic hollow fiber membrane composite body, then connecting the conductive material coupled hydrophobic hollow fiber membrane composite body with a membrane module shell, and meanwhile, alternately arranging hydrophilic membrane materials and the composite body according to a preset interval to obtain the hydrophobic hollow fiber membrane composite body. And finally obtaining the composite cathode assembly. The problems that in an existing electro-Fenton technology, the oxygen utilization rate is low, mass transfer resistance is large, the contact efficiency of H2O2 and ferrous ions is low, and system energy consumption is high are solved.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, and in particular to a method for preparing and applying an electro-Fenton curtain composite cathode assembly based on a hydrophilic / hydrophobic hollow fiber membrane. Background Technology

[0002] Electro-Fenton technology, as a highly efficient and environmentally friendly advanced oxidation technology, works by in-situ electro-synthesizing hydrogen peroxide (H2O2) at the cathode using oxygen. Upon contact with an iron-based catalyst, H2O2 generates highly oxidizing hydroxyl radicals, thereby efficiently removing recalcitrant organic pollutants. Due to its mild reaction conditions and the absence of large amounts of additional chemical oxidants, this technology shows broad application prospects in wastewater treatment in industries such as pharmaceuticals, dyeing, chemicals, and textiles. However, the large-scale promotion of electro-Fenton technology is consistently limited by two key factors: efficiency and energy consumption. These factors include the efficiency of H2O2 electro-synthesis at the cathode and the reaction rate of H2O2 with ferrous ions (Fe2O3). 2+ The mass transfer contact efficiency of the cathode directly determines the pollutant degradation effect; while the power consumption of cathode oxygen supply and Fe 2+ The energy consumption of addition and mixing constitutes the main part of the system's operating energy consumption, becoming a major bottleneck restricting the implementation of the technology.

[0003] To improve the performance of electro-Fenton technology, numerous research and development efforts have been undertaken in related fields, resulting in the publication of a series of patented technologies. For example, CN110255672A discloses an electro-Fenton cathode membrane material with aeration function, its preparation method, and its application. This material disperses carbon black and polyethylene wax into a polyphenylene sulfide ultrafine fiber base fabric via spraying, followed by heat setting and hot rolling to prepare a fabric-like cathode membrane material, achieving a combination of membrane-side aeration and in-situ H2O2 synthesis. CN109678225A discloses a method for preparing an integrated carbon nanotube electro-Fenton membrane and its application. This method uses vacuum filtration and high-pressure fixation to load iron-modified carbon nanotubes and hierarchical porous carbon onto a flat ceramic membrane, forming... An integrated electro-Fenton membrane structure was constructed. Publication CN112803030A discloses a method for preparing and applying an electro-Fenton composite membrane cathode, which disperses iron-containing catalyst nanoparticles in an electrospinning solution and coats conductive carbon material with electrostatic fibers using electrospinning technology to prepare the composite membrane cathode. Furthermore, publication CN119612702A discloses an electro-Fenton wastewater treatment device, method, and application based on iron cycling and a conductive aeration membrane cathode. This design features a flat-plate conductive aeration membrane cathode, which loads the active layer through vacuum filtration, balancing H2O2 synthesis and Fe... 2+ / Fe 3+ Circulation function. These research and development efforts all revolve around goals such as improving oxygen utilization and enhancing catalyst performance, thus driving the development of electro-Fenton cathode technology.

[0004] Despite some progress in current research and development, many shortcomings remain. Among these, the efficiency and energy consumption of the electro-Fenton system are key factors restricting its widespread adoption. The efficiency of the electro-Fenton system is affected by various factors, including the efficiency of cathode electrosynthesis of hydrogen peroxide and the reaction between hydrogen peroxide and Fe. 2+ The mass transfer contact efficiency is undoubtedly a key factor affecting its overall efficiency; the energy consumption of the electric Fenton system mainly includes the power consumption for cathode oxygen supply and Fe... 2+ Energy consumption from adding the mixture. Currently, cathode oxygen supply mostly adopts the form of external oxygen supply and cathode separation. Its main drawback is the low utilization rate of the supplied oxygen, resulting in high system energy consumption; reducing agent Fe 2+ There are several ways to supply it, one of which is through sacrificial anodizing to produce Fe. 2+ This is often accompanied by electrode passivation, affecting the system's electron transfer efficiency and increasing system energy consumption; one method is to add Fe at specific points in the reactor. 2+ One method involves catalytic mixing and mass transfer through contact with hydrogen peroxide, which requires additional mixing equipment; another method involves using Fe... 2+ Loaded on the cathode in different ways, but as the electro-Fenton system operates, Fe 2+ It will gradually be lost, strengthening Fe. 2+ and Fe 3+ The cyclic regeneration is crucial for the stability of the electro-Fenton system, but this requires a complex preparation process. Therefore, improving the utilization rate of cathode oxygen with lower power consumption, while simultaneously enhancing the production of hydrogen peroxide and Fe, is essential. 2+ Contact efficiency is crucial for the efficient and stable operation of an electric Fenton system. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the present invention aims to provide a method for preparing and applying an electro-Fenton curtain composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membranes. This method addresses the problems of low oxygen utilization, high mass transfer resistance, low contact efficiency between H2O2 and ferrous ions, and high system energy consumption in existing electro-Fenton technologies. It achieves synergy between in-situ efficient electrosynthesis of H2O2 under low aeration and precise online addition of ferrous ions, thereby shortening the mass transfer distance, improving the utilization rate of oxidants and reductants, and enhancing the degradation rate of pollutants.

[0006] To achieve the above objectives, the present invention provides the following solution: a method for preparing a Fenton curtain-type composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membrane, comprising the following steps: S1. Cut the conductive material into equal lengths, place them in the pretreatment solution and deionized water for ultrasonic cleaning, and dry them to obtain the pretreated conductive material. S2. Cut the hydrophilic hollow fiber membrane and the hydrophobic hollow fiber membrane into equal lengths, place them in the pretreatment solution and deionized water in sequence for ultrasonic cleaning, and dry them to obtain the pretreated hydrophilic membrane material and hydrophobic membrane material respectively. S3. Insert a support material into the pretreated conductive material to obtain a conductive material with support. S4. Fix the supportive conductive material onto the pretreated hydrophobic membrane material to obtain a conductive material coupled with a hydrophobic hollow fiber membrane composite. S5. The conductive material is coupled to the hydrophobic hollow fiber membrane composite and connected to the membrane module shell. At the same time, the hydrophilic membrane material is alternately arranged with the composite at a preset interval to finally obtain the electro-Fenton curtain composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane.

[0007] Preferably, in S1, the conductive material is selected from one of carbon felt, braided tube, and plastic conductive material.

[0008] Preferably, in S1 and S2, the pretreatment solution is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1; the drying temperature is 80~100℃, and the drying time is 2~3h.

[0009] Preferably, in S2, the hydrophilic hollow fiber membrane is made of one or more of polysulfone, polyvinylidene fluoride, and polypropylene; the hydrophobic hollow fiber membrane is made of one or more of polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene; and the membrane lengths of the hydrophilic and hydrophobic hollow fiber membranes are 6-15 cm.

[0010] Preferably, in S3, the support material is a conductive wire, which is selected from one or more of titanium wire and nickel wire.

[0011] Preferably, in S4, the form in which the supporting conductive material is fixed on the pretreated hydrophobic film material includes, but is not limited to, winding or wrapping; in S5, the preset spacing is 4~10mm.

[0012] Preferably, in S5, the membrane module housing includes a membrane housing air inlet top cover and a membrane housing liquid inlet base, the membrane housing air inlet top cover being in communication with the hydrophobic membrane material, and the membrane housing liquid inlet base being in communication with the hydrophilic membrane material.

[0013] Secondly, the present invention also provides a composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membranes prepared by the above preparation method, which is composed of alternating arrangements of hydrophobic hollow fiber membranes and hydrophilic hollow fiber membranes coupled with conductive materials.

[0014] On the other hand, the present invention also provides an application of the above-mentioned electro-Fenton curtain composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membrane in treating pollutants in enhanced electro-Fenton reaction.

[0015] Preferably, the electro-Fenton system used in the application includes a Fenton degradation unit, an oxygen supply unit, a reducing agent dosing unit, and a stirring unit; The Fenton degradation unit has an anode assembly in its degradation tank. The composite cathode assembly and the anode assembly are respectively connected to an ammeter and a voltmeter. The magnetic rotor of the stirring unit is located in the degradation tank. The oxygen tank of the oxygen supply unit is connected to the air inlet cover of the membrane shell through an oxygen supply pipe. A gas flow meter is installed on the oxygen supply pipe, and an oxygen pressure gauge is installed on the oxygen tank. The reducing agent container of the reducing agent dosing unit is connected to the liquid inlet base of the membrane shell through a peristaltic pump. A liquid flow meter is installed on the pipe of the peristaltic pump.

[0016] Compared with the prior art, the present invention discloses at least the following technical effects: (1) This invention significantly improves oxygen utilization and hydrogen peroxide generation efficiency, effectively reducing system energy consumption. By combining hollow fiber hydrophobic membranes with conductive materials such as carbon felt, the micropores on the surface of the hydrophobic membrane are utilized to efficiently supply oxygen at low pressure. The submicron-sized bubbles formed after aeration have a large specific surface area. Combined with the three-dimensional pore structure of the conductive material, the oxygen mass transfer distance is shortened, enabling oxygen to undergo a two-electron reduction reaction at low aeration rates, thus achieving efficient in-situ electrosynthesis of hydrogen peroxide. Furthermore, this invention not only solves the problems of low O2 utilization, low H2O2 yield, and poor selectivity in traditional electro-Fenton technology, but also significantly reduces the power consumption of cathode oxygen supply, providing technical support for low-energy operation of the system.

[0017] (2) This invention significantly optimizes mass transfer efficiency and improves pollutant degradation rate through the alternating arrangement and functional division of hydrophilic / hydrophobic hollow fiber membranes. The hydrophilic hollow fiber membrane enables precise online addition of ferrous ion reducing agent, allowing it to efficiently contact hydrogen peroxide generated in situ by the hydrophobic membrane, fundamentally shortening the mass transfer distance between the two and completely solving the problem of high mass transfer resistance in traditional processes. At the same time, implementing this invention does not require additional mixing equipment, saving equipment investment and mixing energy consumption, and allowing the ferrous ions generated by hydrolysis to react with hydrogen peroxide in a timely manner, effectively saving reaction time and significantly improving the degradation rate of organic matter, thus providing a solution for wastewater treatment.

[0018] (3) While enhancing reaction efficiency, this invention also possesses multiple additional advantages, improving the practicality and safety of the technology. On the one hand, the composite cathode assembly structure of this invention can reduce sludge production, lower charge transfer resistance, and better utilize the oxygen reduction reaction (ORR) to improve conductivity and system operational stability. On the other hand, the composite cathode assembly supports modular operation, is suitable for industrial-scale application scenarios, and has good potential for widespread adoption. In addition, the in-situ synthesis of hydrogen peroxide avoids the additional addition of hydrogen peroxide in the existing Fenton system, fundamentally reducing the safety hazards in the transportation and storage of hydrogen peroxide, further improving the practicality and safety of the technology. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of a method for preparing an electro-Fenton curtain composite cathode assembly based on a hydrophilic / hydrophobic hollow fiber membrane according to the present invention. Figure 2 This is a schematic diagram showing the structure and internal reaction details of the electro-Fenton curtain composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membrane provided in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the membrane module housing structure provided in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of the electro-Fenton reaction system provided in Embodiment 2 of the present invention; Figure 5 Line graph showing hydrogen peroxide production under different oxygen aeration rates provided in Test Example 1 of this invention; Figure 6 Line graph showing the hydrogen peroxide production under different current intensities provided in Test Example 1 of the present invention; Figure 7 This is a line graph showing the degradation of methylene blue under optimal conditions, provided in Test Example 2 of the present invention. Figure 8 This is a line graph showing the degradation of COD under optimal conditions provided in Test Example 3 of the present invention; Figure 9 The graph shows the hydrogen peroxide production of a conventional electro-Fenton under optimal operating conditions, as provided in Comparative Example 1 of this invention. Figure 10 This is a line graph showing the degradation of methylene blue by a conventional electro-Fenton under optimal operating conditions, as provided in Comparative Example 2 of this invention.

[0021] Explanation of reference numerals in the attached figures: 1. Conductive wire; 2. Carbon felt; 3. Polyvinylidene fluoride hollow fiber hydrophobic membrane; 4. Polyvinylidene fluoride hollow fiber hydrophilic membrane; 5. Oxygen inlet; 6. Reducing agent inlet; 7. Hydrophobic membrane connecting channel at the oxygen inlet end; 8. Hydrophilic membrane dead end at the oxygen inlet end; 9. Hydrophilic membrane connecting channel at the reducing agent inlet end; 10. Hydrophobic membrane dead end at the reducing agent inlet end; 11. Curtain-type composite cathode; 12. Ti / IrO2 / RuO2 anode; 13. Electrode clamp; 14. Fenton degradation unit; 15. Oxygen tank; 16. Gas flow meter; 17. Liquid flow meter; 18. Reducing agent solution; 19. Peristaltic pump; 20. Stirring unit; 21. Ammeter and voltmeter. Detailed Implementation

[0022] The technical solutions of 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.

[0023] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] Example 1 like Figure 1 As shown, this embodiment provides a method for preparing a Fenton curtain-type composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane, including the following steps: S1. The conductive material is cut into equal lengths and placed in a pretreatment solution and deionized water for ultrasonic cleaning. After drying, the pretreated conductive material is obtained.

[0025] Specifically, the conductive material is selected from carbon felt, braided tubing, and plastic conductive material. In this embodiment, the pretreatment solution is a 1:1 volume ratio of ethanol to water. The conductive material is first ultrasonically cleaned in the pretreatment solution, and then ultrasonically cleaned again in deionized water. Ultrasonic cleaning removes impurities from the surface of the conductive material. The drying conditions are 80-100°C for 2-3 hours. In this embodiment, a drying temperature of 80°C and a drying time of 2 hours are selected to ensure the conductive material surface is dry and clean, avoiding residual moisture that could affect the subsequent bonding with the support material and membrane material.

[0026] S2. Cut the hydrophilic hollow fiber membrane and the hydrophobic hollow fiber membrane into equal lengths, place them in the pretreatment solution and deionized water in sequence for ultrasonic cleaning, and dry them to obtain pretreated hydrophilic membrane material and hydrophobic membrane material respectively.

[0027] Specifically, the hydrophilic hollow fiber membrane is made of one or more of polysulfone, polyvinylidene fluoride, and polypropylene, and in this embodiment, it is polyvinylidene fluoride; the hydrophobic hollow fiber membrane is made of one or more of polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene, and in this embodiment, it is polyvinylidene fluoride; and the membrane length of both hollow fiber membranes is 6~15cm, and 6cm is selected in this embodiment; the pretreatment solution is the same as S1, that is, a mixed solution of ethanol and water in a 1:1 volume ratio, and the surfactant on the membrane surface is removed and residual impurities are prepared by two ultrasonic cleanings; the drying conditions are also 80~100℃ for 2~3h, to ensure that the hydrophobicity and hydrophilicity of the membrane material are not affected by moisture, and at the same time improve the structural stability of the membrane material.

[0028] S3. Insert a support material into the pretreated conductive material to obtain a conductive material with support.

[0029] Specifically, the support material is a conductive wire, selected from one or more of titanium wire and nickel wire. In this embodiment, the support material is inserted through the pre-treated conductive material along its length. This enhances the mechanical strength of the conductive material, preventing deformation and breakage during subsequent winding, fixing, and use. It also strengthens the conductivity of the conductive material, ensuring efficient electron transport.

[0030] S4. Fix the supporting conductive material onto the pretreated hydrophobic membrane material to obtain a conductive material coupled with a hydrophobic hollow fiber membrane composite.

[0031] Specifically, the forms in which the supporting conductive material is fixed on the pretreated hydrophobic membrane material include, but are not limited to, winding or covering. This embodiment uses the winding method. During the winding process, the winding linear density of the supporting conductive material is controlled to be 0.1~0.4, while in this embodiment the winding density is 1-2 g / m. The winding method is spiral uniform winding to ensure that the conductive material and the hydrophobic membrane material are closely attached. This ensures that the conductive material uniformly covers the membrane material without blocking the micropores on the surface of the hydrophobic membrane material, thus reserving channels for subsequent oxygen transport and hydrogen peroxide synthesis.

[0032] S5. The conductive material is coupled to the hydrophobic hollow fiber membrane composite and connected to the membrane module shell. At the same time, the hydrophilic membrane material is alternately arranged with the composite at a preset interval to finally obtain the electro-Fenton curtain composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane.

[0033] Specifically, such as Figure 2 and Figure 3As shown, the membrane module housing includes a membrane housing air inlet top cover and a membrane housing liquid inlet base. The membrane housing air inlet top cover is connected to the hydrophobic membrane material and is used for the introduction of oxygen into the subsequent oxygen supply unit. The membrane housing liquid inlet base is connected to the hydrophilic membrane material and is used for the introduction of reducing agent solution into the subsequent reducing agent dosing unit. The preset spacing between the hydrophilic membrane material and the conductive material coupled with the hydrophobic hollow fiber membrane composite is 4~10mm. In this embodiment, 4mm is selected. The alternating arrangement is that the conductive material coupled with the hydrophobic hollow fiber membrane composite - the hydrophilic membrane material - the conductive material coupled with the hydrophobic hollow fiber membrane composite are distributed alternately.

[0034] After assembly in this embodiment, the polyvinylidene fluoride hollow fiber hydrophobic membrane 3 can receive oxygen through the oxygen inlet 5 and the hydrophobic membrane connecting channel 7 at the oxygen inlet end. Its hydrophobicity can prevent electrolytes in water from entering the membrane, allowing only gaseous oxygen to diffuse through the membrane pores to the surface supporting conductive material (such as carbon felt 2). The three-dimensional porous structure of the supporting conductive material can efficiently capture and adsorb submicron-sized oxygen bubbles, and under the action of a DC electric field, electrochemical reduction occurs to generate hydrogen peroxide in situ. The polyvinylidene fluoride hollow fiber hydrophilic membrane 4 receives the reducing agent solution through the reducing agent inlet 6 and the hydrophilic membrane connecting channel 9 at the reducing agent inlet end. The ferrous ions generated after hydrolysis can efficiently diffuse to the main solution, and quickly come into spatial contact with the hydrogen peroxide generated in situ by the hydrophobic membrane and undergo a Fenton reaction. The dead ends 8 of the hydrophilic membrane at the oxygen inlet end and 10 of the hydrophobic membrane at the reducing agent inlet end are used to ensure the sealing of the fluid channel, prevent cross-flow of oxygen and reducing agent solution, and ensure the orderly progress of the reaction.

[0035] Example 2 Based on the curtain-type composite cathode assembly 11 prepared in Example 1, it is applied to treat pollutants in an enhanced electro-Fenton reaction, wherein the electro-Fenton system used in the above application is as follows: Figure 4 As shown, it specifically includes a Fenton degradation unit 14, an oxygen supply unit, a reducing agent addition unit, and a stirring unit 20.

[0036] In this embodiment, the Fenton degradation unit 14 uses an electrolytic cell as the main reaction vessel. In addition to the curtain-type composite cathode 11 prepared in Example 1, the electrolytic cell is also equipped with an anode assembly, which is a Ti / IrO2 / RuO2 anode 12. Both the curtain-type composite cathode 11 and the Ti / IrO2 / RuO2 anode 12 are fixed in the electrolytic cell by electrode clamps 13, and both are electrically connected to ammeters and voltmeters 21 to monitor the current and voltage parameters during the reaction process in real time, ensuring the stable progress of the electrochemical reaction. The magnetic rotor of the stirring unit 20 is placed directly inside the electrolytic cell, which can enhance mass transfer within the reaction system through gentle stirring, further improving the contact efficiency between pollutants and hydroxyl radicals.

[0037] The oxygen supply unit includes an oxygen tank 15, an oxygen supply pipeline, a gas flow meter 16, and an oxygen pressure gauge. The oxygen pressure gauge mounted on the oxygen tank 15 is used to monitor the oxygen pressure inside the tank. The oxygen tank 15 is connected to the oxygen inlet 5 of the curtain-type composite cathode 11 through the oxygen supply pipeline. The gas flow meter 16 connected in series on the oxygen supply pipeline can accurately control the oxygen aeration rate, so that the oxygen enters the hydrophobic membrane connecting channel 7 at the oxygen inlet end of the curtain-type composite cathode 11 through the oxygen inlet 5 at a preset rate, and finally diffuses to the surface of the conductive material through the micropores of the polyvinylidene fluoride hollow fiber hydrophobic membrane 3, providing sufficient reactants for the in-situ electrosynthesis of hydrogen peroxide.

[0038] The reducing agent dosing unit includes a storage container for reducing agent solution 18, a peristaltic pump 19, a dosing pipe, and a liquid flow meter 17. The storage container for reducing agent solution 18 contains a ferrous ion-based reducing agent solution. It is connected to the input end of the peristaltic pump 19 through the dosing pipe. The output end of the peristaltic pump 19 is connected to the reducing agent inlet 6 of the curtain-type composite cathode 11 through the dosing pipe. The liquid flow meter 17 connected in series on the dosing pipe can accurately control the dosing rate of the reducing agent solution. The reducing agent solution 18 is driven by the peristaltic pump 19 and enters the hydrophilic membrane connecting channel 9 at the reducing agent inlet end through the reducing agent inlet 6. Then, it diffuses efficiently into the reaction system of the electrolytic cell through the polyvinylidene fluoride hollow fiber hydrophilic membrane 4 and undergoes a Fenton reaction with the hydrogen peroxide generated in situ by the hydrophobic membrane.

[0039] When the electro-Fenton system is running, the oxygen supply unit continuously supplies oxygen to the curtain-type composite cathode 11, and the reducing agent dosing unit simultaneously and precisely adds reducing agent solution 18. Under the action of a stable electric field monitored by the ammeter and voltmeter 21, the curtain-type composite cathode 11 achieves the synergy of in-situ synthesis of hydrogen peroxide and online addition of ferrous ions, and efficiently generates hydroxyl radicals through the Fenton reaction, thereby degrading the recalcitrant organic pollutants in the electrolytic cell.

[0040] To further verify the comprehensive performance of the composite cathode assembly prepared in Example 1 and the electro-Fenton system in Example 2, and to clarify their hydrogen peroxide generation efficiency, pollutant degradation effect, and optimal operating parameters, the following three test examples are provided. The specific test procedures and results are as follows: Test Example 1 (1) Effect of different oxygen aeration rates on hydrogen peroxide production Using the electro-Fenton system from Example 2, in a 0.05M anhydrous sodium sulfate electrolyte system at pH=3, oxygen aeration rates of 5 mL / min, 10 mL / min, 15 mL / min, and 20 mL / min were set, with other conditions kept constant. The yield of in-situ electro-synthesis of hydrogen peroxide at the cathode under different aeration rates was tested. The test results are as follows: Figure 5As shown in the figure, under different aeration rates, the hydrogen peroxide production initially increased rapidly with the extension of reaction time, and gradually stabilized after about 60 min. Among them, when the oxygen aeration rate was 10 mL / min, the hydrogen peroxide production was significantly higher than the other three groups throughout the entire reaction cycle, reaching a peak in the later stage of the reaction and maintaining the highest level. This indicates that the oxygen mass transfer efficiency and the cathode oxygen reduction reaction efficiency were optimally matched under this aeration rate. Further increasing the aeration rate (15 mL / min, 20 mL / min) could not further increase the production, but instead resulted in waste due to insufficient oxygen reaction. Therefore, 10 mL / min is the optimal oxygen aeration rate.

[0041] (2) Effect of different current intensities on hydrogen peroxide production Using the same electrolyte system and electro-Fenton system as described above, with a fixed oxygen aeration rate of 10 mL / min, and current intensities of 10 mA, 20 mA, 30 mA, 40 mA, and 50 mA respectively, the amount of hydrogen peroxide generated under different current intensities was tested. The results are as follows: Figure 6 As shown, the hydrogen peroxide production gradually increases with the increase of current intensity. When the current intensity is 50mA, the hydrogen peroxide production reaches the highest value. This is because appropriately increasing the current intensity can promote the two-electron reaction of oxygen reduction at the cathode. However, if the current is further increased, it may trigger side reactions such as hydrogen evolution. Therefore, 50mA is the optimal current intensity for this system.

[0042] Test Example 2 Based on the optimal operating conditions determined in Test Example 1 (pH=3, oxygen aeration rate 10 mL / min, current intensity 50 mA), the electro-Fenton system of Example 2 was used to conduct degradation tests on methylene blue as a simulated pollutant. During the test, the absorbance change of methylene blue was monitored in real time, and its removal rate was calculated. The results are as follows: Figure 7 As shown, the removal rate of methylene blue can reach 99% after 5 minutes of reaction, indicating that the composite cathode component of the present invention can efficiently realize the synergistic reaction of hydrogen peroxide and ferrous ions, rapidly generate hydroxyl radicals, and has a strong degradation ability for organic pollutants. The mass transfer efficiency and reaction rate are significantly better than those of the traditional electro-Fenton system.

[0043] Test Example 3 Using the same optimal operating conditions as in Test Example 1, the electro-Fenton system of Example 2 was used to degrade actual dyeing and printing wastewater. The chemical oxygen demand (COD) removal rate was used as the evaluation index, and the COD change was monitored within 80 minutes of the reaction. The test results are as follows: Figure 8As shown, the COD removal rate of dyeing and printing wastewater gradually increases with the extension of reaction time, reaching 56% after 80 minutes. This result verifies the applicability of the composite cathode component and electro-Fenton system of the present invention in actual industrial wastewater treatment, which can effectively degrade complex and difficult-to-treat organic pollutants, providing reliable technical support for large-scale wastewater treatment.

[0044] Comparative Example 1 Using the optimal operating conditions of Test Example 1 (pH=3, oxygen aeration rate 10 mL / min, current intensity 50 mA), a comparative experiment was conducted using a conventional electro-Fenton converter to generate hydrogen peroxide. In this comparative experiment, the cathode and anode were made of carbon felt and iron plates of the same size as the anode plate in Example 2. Fe was deposited on the iron plate at the anode. 2+ The conductive cathode transfers electrons to generate hydrogen peroxide. This comparative experiment used an aeration head for aeration, with a 2cm gap between the two electrodes. The test results are as follows: Figure 9 As shown, the hydrogen peroxide yield of the conventional electro-Fenton at 120 min is 25 mg / L, which is much lower than the hydrogen peroxide yield of the composite cathode module of the present invention. This result verifies that the composite cathode module of the present invention achieves in-situ efficient electro-synthesis of H2O2 with low aeration compared to the existing electro-Fenton technology.

[0045] Comparative Example 2 The optimal operating conditions of Test Example 1 (pH=3, oxygen aeration rate 10 mL / min, current intensity 50 mA) were used to conduct an experiment on the degradation of methylene blue using a conventional electro-Fenton circuit. The comparative experimental setup was the same as in Test Example 4. The test results are as follows: Figure 10 As shown, it can be found that the degradation rate of methylene blue by the conventional electro-Fenton at 60 min is only 23.7%, which is far lower than the degradation capacity of the composite cathode module of the present invention. Therefore, this result indirectly verifies that the composite cathode module of the present invention has a good degradation capacity for pollutants and can effectively treat organic pollutants.

[0046] Therefore, the above-mentioned preparation method and application of an electro-Fenton curtain composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane solves the problems of low oxygen utilization, high mass transfer resistance, low contact efficiency between H2O2 and ferrous ions, and high system energy consumption in existing electro-Fenton technology. It achieves the synergy of in-situ high-efficiency electrosynthesis of H2O2 and online precise addition of ferrous ions under low aeration, shortens the mass transfer distance, improves the utilization rate of oxidant and reductant, and enhances the degradation rate of pollutants.

[0047] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0048] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing a Fenton curtain-type composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane, characterized in that, Includes the following steps: S1. Cut the conductive material into equal lengths, place them in the pretreatment solution and deionized water for ultrasonic cleaning, and dry them to obtain the pretreated conductive material. S2. Cut the hydrophilic hollow fiber membrane and the hydrophobic hollow fiber membrane into equal lengths, place them in the pretreatment solution and deionized water in sequence for ultrasonic cleaning, and dry them to obtain the pretreated hydrophilic membrane material and hydrophobic membrane material respectively. S3. Insert a support material into the pretreated conductive material to obtain a conductive material with support. S4. Fix the supportive conductive material onto the pretreated hydrophobic membrane material to obtain a conductive material coupled with a hydrophobic hollow fiber membrane composite. S5. The conductive material is coupled to the hydrophobic hollow fiber membrane composite and connected to the membrane module shell. At the same time, the hydrophilic membrane material is alternately arranged with the composite at a preset interval to finally obtain the electro-Fenton curtain composite cathode module based on hydrophilic / hydrophobic hollow fiber membrane.

2. The preparation method according to claim 1, characterized in that, In S1, the conductive material is selected from one of carbon felt, braided tube, and plastic conductive material.

3. The preparation method according to claim 1, characterized in that, In S1 and S2, the pretreatment solution is a mixture of ethanol and water, and the volume ratio of ethanol to water is 1:1; the drying temperature is 80~100℃, and the drying time is 2~3h.

4. The preparation method according to claim 1, characterized in that, In S2, the hydrophilic hollow fiber membrane is made of one or more of polysulfone, polyvinylidene fluoride, and polypropylene; the hydrophobic hollow fiber membrane is made of one or more of polytetrafluoroethylene, polyvinylidene fluoride, and polypropylene; and the membrane lengths of the hydrophilic and hydrophobic hollow fiber membranes are 6-15 cm.

5. The preparation method according to claim 1, characterized in that, In S3, the supporting material is a conductive wire, which is selected from one or more of titanium wire and nickel wire.

6. The preparation method according to claim 1, characterized in that, In S4, the form in which the supporting conductive material is fixed on the pretreated hydrophobic membrane material includes, but is not limited to, winding or wrapping; in S5, the preset spacing is 4~10mm.

7. The preparation method according to claim 1, characterized in that, In S5, the membrane module housing includes a membrane housing air inlet top cover and a membrane housing liquid inlet base. The membrane housing air inlet top cover is in communication with the hydrophobic membrane material, and the membrane housing liquid inlet base is in communication with the hydrophilic membrane material.

8. A composite cathode assembly based on a hydrophilic / hydrophobic hollow fiber membrane, prepared according to any one of claims 1 to 7, characterized in that, It is composed of alternating arrangements of hollow fiber hydrophobic membranes and hollow fiber hydrophilic membranes coupled with conductive materials.

9. The application of the electro-Fenton curtain composite cathode assembly based on hydrophilic / hydrophobic hollow fiber membrane according to claim 8 in the treatment of pollutants in enhanced electro-Fenton reaction.

10. The application according to claim 9, characterized in that, The application uses an electro-Fenton system that includes a Fenton degradation unit, an oxygen supply unit, a reducing agent dosing unit, and a stirring unit. The Fenton degradation unit has an anode assembly in its degradation tank. The composite cathode assembly and the anode assembly are respectively connected to an ammeter and a voltmeter. The magnetic rotor of the stirring unit is located in the degradation tank. The oxygen tank of the oxygen supply unit is connected to the air inlet cover of the membrane housing through an oxygen supply pipe. A gas flow meter is installed on the oxygen supply pipe, and an oxygen pressure gauge is installed on the oxygen tank. The reducing agent container of the reducing agent dosing unit is connected to the liquid inlet base of the membrane housing through a peristaltic pump. A liquid flow meter is installed on the pipe of the peristaltic pump.

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