Palladium-based composite electro-catalysis membrane for removing halogen-containing pollutants in water and preparation method and application of assembly of palladium-based composite electro-catalysis membrane

Abstract

The invention discloses a palladium-based composite electro-catalysis membrane for removing halogen-containing pollutants in water and a preparation method and application of an assembly of the palladium-based composite electro-catalysis membrane, and belongs to the technical field of water treatment. The method comprises the following steps: 1, preparing a titanium nitride hollow fiber membrane; 2, loading the titanium nitride hollow fiber membrane into a membrane module; and thirdly, palladium nanoparticles are loaded through a circulation type electro-deposition method. The palladium-based composite electro-catalysis membrane assembly for removing the halogen-containing pollutants in the water is used for removing trace halogen-containing pollutants in the water; according to the palladium-based composite electro-catalytic membrane provided by the invention, the mass transfer and reaction efficiency is remarkably enhanced through forced convection and pore channel confinement effects introduced in the membrane filtration process, so that the treatment efficiency is greatly improved while the energy consumption is reduced; the removal rate of the membrane on trace halogen-containing pollutants under a complex water quality condition can exceed 99.9%, the reaction rate constant of the membrane is improved by 2-4 orders of magnitude compared with that of a traditional technology, the energy consumption of water treatment per ton can be reduced to 0.1 kWh or below, and the membrane shows a remarkable energy efficiency advantage.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for preparing and applying a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water. Background Technology

[0002] Halogenated contaminants commonly found in drinking water, including chlorinated / bromine / iodinated organic compounds, chloroxylates, and bromates, pose a serious threat to public health. These contaminants primarily originate from two sources: first, source water pollution caused by anthropogenic discharge of halogenated chemicals into water bodies; and second, halogenated byproducts generated during conventional water treatment processes such as chemical oxidation and disinfection. Studies have shown that most halogenated contaminants possess significant biotoxicity, including carcinogenic, teratogenic, and mutagenic effects, and can have long-term adverse effects on human health even at extremely low concentrations. Therefore, developing efficient, economical, and environmentally friendly removal technologies to mitigate their potential risks is of significant practical importance.

[0003] Currently, the main methods for removing halogenated pollutants include adsorption, oxidation, and reduction. Among these, reduction technology stands out due to its high reaction selectivity and fewer byproducts. Typical reduction methods include electrocatalytic reduction, hydrogen catalytic hydrogenation, and advanced reduction technologies based on hydrated electrons. These technologies can effectively break carbon-halogen bonds or halogen-oxygen bonds, thereby achieving dehalogenation conversion. Electrocatalytic reduction, as a relatively sustainable strategy, can achieve dehalogenation reactions through direct electron transfer or reaction with electrochemically generated atomic hydrogen. This process can be carried out at ambient temperature and pressure without the need for external chemical reagents or harsh reaction conditions, offering advantages such as ease of operation and environmental friendliness. However, existing electrochemical dehalogenation technologies still have the following shortcomings: firstly, the reaction kinetics are slow, limiting the improvement of dehalogenation efficiency; secondly, energy consumption is high, especially under environmentally relevant low concentration conditions, where electrode reactions are difficult to fully proceed. To address this issue, flow-through electrocatalytic membrane technology, proposed in recent years, can significantly accelerate reaction kinetics by improving mass transfer efficiency and utilizing the spatial confinement effect within the membrane channels, demonstrating great development potential.

[0004] Currently, palladium-based electrocatalysts exhibit excellent catalytic activity in the reduction and removal of halogen-containing pollutants, but systematic research on palladium-based electrocatalytic membranes remains relatively scarce. On the one hand, existing palladium catalytic systems are mostly in the form of powder or supported electrodes, lacking system designs that organically integrate with membrane structures. On the other hand, the distribution regulation of palladium within the membrane, the crystal orientation effect, and the reaction mechanism under confined space still lack systematic exploration. Furthermore, compared to planar and tubular membranes, hollow fiber membranes have higher specific surface area and packing density, offering significant advantages in reaction efficiency and engineering applications. Therefore, how to organically integrate the high catalytic activity of palladium with the high mass transfer characteristics of membrane reactors to construct a palladium-based hollow fiber electrocatalytic membrane system that combines high efficiency and stability has become a key scientific and technological problem urgently needing to be solved in this field.

[0005] In summary, developing a palladium-based flow-through electrocatalytic membrane for the efficient removal of halogen-containing pollutants from water not only has the potential to overcome the limitations of traditional electrochemical reduction processes in terms of kinetics and energy consumption, but also fills the gap in material design and mechanism research in this field, thus possessing significant scientific value and broad application prospects. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a method for preparing and applying a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water.

[0007] A method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water is specifically carried out according to the following steps:

[0008] I. Preparation of titanium nitride hollow fiber membranes:

[0009] ① Mix titanium nitride powder, alumina powder, polymethyl methacrylate powder and polyvinylpyrrolidone powder in a certain proportion, then add them to a certain amount of organic solvent, ball mill for a certain time to make them evenly mixed, and finally perform vacuum degassing to obtain a uniform casting solution.

[0010] ② The casting liquid and coagulant are simultaneously extruded from the spinneret to form hollow fibers. The fibers are then soaked in the coagulant for a sufficient time to allow for complete phase transformation. The hollow fibers are then removed from the coagulant, shaped and dried, and finally calcined at high temperature in a nitrogen or argon atmosphere to obtain titanium nitride hollow fiber membrane.

[0011] II. The titanium nitride hollow fiber membrane is loaded into the membrane module to obtain the membrane module based on the titanium nitride hollow fiber membrane:

[0012] The membrane module based on titanium nitride hollow fiber membrane includes a membrane shell 1, a removable cover 2, an inlet 13, an outlet 3, a thread 4, a connecting wire 5, a titanium nitride hollow fiber membrane 6, a reference electrode 7, a titanium metal grid 8, a counter electrode grid / sheet 9, a connecting wire 10 between the titanium metal grid and the counter electrode grid / sheet, a positioning baffle 11 for the titanium metal grid, and a positioning baffle 12 for the counter electrode grid / sheet.

[0013] III. Loading palladium nanoparticles using a flow-through electrodeposition method:

[0014] ① Preparation of palladium electrodeposition solution:

[0015] Sulfate, palladium salt, inorganic bromide, and polyvinylpyrrolidone were dissolved in water, stirred until homogeneous, and the pH of the system was adjusted to 2.0 to obtain the electrodeposition solution.

[0016] ② Palladium nanoparticles were loaded using a flow-through electrodeposition method:

[0017] In dead-end filtration mode, the membrane module based on titanium nitride hollow fiber membrane is powered on and cyclic voltammetry electrodeposition is performed, with the membrane flux of the electrodeposition solution maintained at 100–500 L·m⁻¹. -2 ·h -1 The scanning potential range of the cyclic voltammetry is 0.1 to -0.4 V vs RHE, the potential scanning rate is 2 to 10 mV / s, and the number of scan cycles is 2 to 10.

[0018] ③ Cleaning and drying:

[0019] The electrodeposition solution inside the membrane module was replaced with deionized water at a concentration of 100–500 L·m⁻¹. -2 ·h -1 At a membrane flux of 10-30 min, after filtration and cleaning, the membrane was dried at room temperature. Palladium nanoparticles were loaded onto the surface of titanium nitride hollow fiber membrane 6 to obtain a palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water and a palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water.

[0020] A palladium-based composite electrocatalytic membrane module for removing halogenated pollutants from water is used to remove trace amounts of halogenated pollutants from water; the halogenated pollutants are organic or inorganic halogenated pollutants; the organic halogenated pollutants are 4-chlorophenol, 4-bromophenol, or 4-iodophenol; the inorganic halogenated pollutants are silver bromate or silver chlorite.

[0021] Effects of the invention:

[0022] I. The titanium nitride hollow fiber membrane developed in this invention possesses high conductivity, excellent chemical stability, and good mechanical strength, making it an ideal support for palladium-based electrocatalysts. This membrane has a large specific surface area and high packing density, effectively reducing the volume occupied by the membrane module. The flow-through electrodeposition process employed in this invention can firmly load palladium nanoparticles onto the surface and internal pores of the substrate membrane, forming a dense palladium catalytic layer with a thickness of less than 1 μm on the membrane surface, which is easily mass-produced. Furthermore, this loading method imparts good structural tunability to the palladium catalytic layer. By adjusting the ratio of palladium salt to inorganic bromide in the electrodeposition solution, the preferred orientation of the palladium nanoparticles and the density of the catalytic layer can be effectively controlled. Appropriately increasing the bromide ion concentration in the electrodeposition solution can promote the exposure of the palladium (111) crystal facets and enhance the density of the palladium layer, thereby significantly improving its reaction kinetics and long-term operational stability in the removal of halogen-containing pollutants.

[0023] II. Compared to the common problems of low reaction efficiency and high energy consumption in traditional electrochemical water treatment technologies, the palladium-based composite electrocatalytic membrane proposed in this invention significantly enhances mass transfer and reaction efficiency through forced convection and pore confinement effects introduced during the membrane filtration process, thereby greatly improving treatment efficiency while reducing energy consumption. This membrane can remove over 99.9% of trace halogenated pollutants under complex water quality conditions, and its reaction rate constant is 2-4 orders of magnitude higher than traditional technologies. Energy consumption per ton of water treated can be reduced to below 0.1 kWh, demonstrating significant energy efficiency advantages. Furthermore, the periodic electrochemical cleaning strategy proposed in this invention can effectively alleviate membrane fouling problems, maintain high membrane permeability and high catalytic activity over the long term, and further improve the stable operation performance of the system.

[0024] The present invention provides a palladium-based composite electrocatalytic membrane and its components for removing halogenated pollutants from water. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the membrane module based on titanium nitride hollow fiber membrane described in step two of Example 1. The diagram shows... Figure 1 This is the first external view. Figure 2 This is the second exterior view. Figure 3 This is the first sectional view. Figure 4 This is the second sectional view. Figure 5 This is the third sectional view; in the figure, 1 is the membrane shell, 2 is the removable cover, 3 is the outlet port, 4 is the thread, 5 is the connection wire port, 6 is the titanium nitride hollow fiber membrane, 7 is the reference electrode port, 8 is the titanium metal grid, 9 is the counter electrode grid / plate, 10 is the connecting wire between the titanium metal grid and the counter electrode grid / plate, 11 is the positioning baffle of the titanium metal grid, 12 is the positioning baffle of the counter electrode grid / plate, and 13 is the inlet port;

[0026] Figure 2 This is a scanning electron microscope image of the cross-sectional structure of the titanium nitride conductive hollow fiber membrane prepared in step one of Example 1;

[0027] Figure 3 This is a graph showing the performance of the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water in Application Example 1, where C is the value of the membrane. p C represents the concentration of pollutants in the effluent. f This represents the concentration of pollutants in the raw water.

[0028] Figure 4 This is a graph showing the performance of the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water in Application Example 1, where C is the value of the membrane. p C represents the concentration of pollutants in the effluent. f This represents the concentration of pollutants in the raw water.

[0029] Figure 5 High-resolution transmission electron microscopy images of palladium nanoparticles in palladium-based composite electrocatalytic membranes used to remove halogenated pollutants from water in Examples 2 and 3;

[0030] Figure 6 The images show a structural comparison of the palladium-based composite electrocatalytic membranes used in Examples 2 and 3 for removing halogen-containing pollutants from water. The left column represents Example 2, and the right column represents Example 3. From top to bottom, the images are a cross-sectional scanning electron microscope image, a cross-sectional elemental energy spectrum, and a surface scanning electron microscope image.

[0031] Figure 7 The graphs show the performance of the palladium-based composite electrocatalytic membrane modules prepared in Examples 2 and 3 for removing halogenated pollutants from water in Application Examples 2 and 3, respectively, in removing 4-chlorophenol. Figure C... p C represents the concentration of 4-chlorophenol in the effluent. f This refers to the concentration of 4-chlorophenol in the raw water.

[0032] Figure 8 The graph shows the stability of the palladium-based composite electrocatalytic membrane module for removing halogenated pollutants from water prepared in Examples 2 and 3 in Application Examples 2 and 3 for the removal of 4-chlorophenol. The vertical axis of the graph is the percentage decrease in removal rate relative to the initial removal rate at different operating times.

[0033] Figure 9 The effect of using the palladium-based composite electrocatalytic membrane module prepared in Example 1 to remove trace amounts of halogenated pollutants from drinking water under different operating modes in Example 4 is demonstrated. Detailed Implementation

[0034] Specific Implementation Method 1: This implementation method is a preparation method of a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, specifically completed according to the following steps:

[0035] I. Preparation of titanium nitride hollow fiber membranes:

[0036] ① Mix titanium nitride powder, alumina powder, polymethyl methacrylate powder and polyvinylpyrrolidone powder in a certain proportion, then add them to a certain amount of organic solvent, ball mill for a certain time to make them evenly mixed, and finally perform vacuum degassing to obtain a uniform casting solution.

[0037] ② The casting liquid and coagulant are simultaneously extruded from the spinneret to form hollow fibers. The fibers are then soaked in the coagulant for a sufficient time to allow for complete phase transformation. The hollow fibers are then removed from the coagulant, shaped and dried, and finally calcined at high temperature in a nitrogen or argon atmosphere to obtain titanium nitride hollow fiber membrane.

[0038] 2. The titanium nitride hollow fiber membrane is loaded into the membrane module to obtain the membrane module based on the titanium nitride hollow fiber membrane;

[0039] The membrane module based on titanium nitride hollow fiber membrane includes a membrane shell 1, a removable cover 2, an inlet 13, an outlet 3, a thread 4, a connecting wire 5, a titanium nitride hollow fiber membrane 6, a reference electrode 7, a titanium metal grid 8, a counter electrode grid / sheet 9, a connecting wire 10 between the titanium metal grid and the counter electrode grid / sheet, a positioning baffle 11 for the titanium metal grid, and a positioning baffle 12 for the counter electrode grid / sheet.

[0040] III. Loading palladium nanoparticles using a flow-through electrodeposition method:

[0041] ① Preparation of palladium electrodeposition solution:

[0042] Sulfate, palladium salt, inorganic bromide, and polyvinylpyrrolidone were dissolved in water, stirred until homogeneous, and the pH of the system was adjusted to 2.0 to obtain the electrodeposition solution.

[0043] ② Palladium nanoparticles were loaded using a flow-through electrodeposition method:

[0044] In dead-end filtration mode, the membrane module based on titanium nitride hollow fiber membrane is powered on and cyclic voltammetry electrodeposition is performed, with the membrane flux of the electrodeposition solution maintained at 100–500 L·m⁻¹. -2 ·h -1 The scanning potential range of the cyclic voltammetry is 0.1 to -0.4 V vs RHE, the potential scanning rate is 2 to 10 mV / s, and the number of scan cycles is 2 to 10.

[0045] ③ Cleaning and drying:

[0046] The electrodeposition solution inside the membrane module was replaced with deionized water at a concentration of 100–500 L·m⁻¹. -2 ·h -1 At a membrane flux of 10-30 min, after filtration and cleaning, the membrane was dried at room temperature. Palladium nanoparticles were loaded onto the surface of titanium nitride hollow fiber membrane 6 to obtain a palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water and a palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water.

[0047] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: the mass ratio of titanium nitride powder to alumina powder in step one ① is (80~95):(5~20); the total mass of titanium nitride powder and alumina powder in step one ① accounts for 45~55% of the mass of the casting solution; the mass of polymethyl methacrylate powder in step one ① accounts for 5~15% of the mass of the casting solution; and the mass of polyvinylpyrrolidone powder in step one ① accounts for 0.5~1.5% of the mass of the casting solution. Other steps are the same as in Specific Implementation Method One.

[0048] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: the organic solvent mentioned in step 1① is N,N-dimethylacetamide; the ball milling time mentioned in step 1① is 12~24 h; and the vacuum degassing treatment time mentioned in step 1① is 30~90 min. Other steps are the same as in Specific Implementation Method 1 or 2.

[0049] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in the following ways: the coagulant in step one to two is water; both the casting solution and the coagulant in step one to two are simultaneously extruded from a spinneret with an outer diameter of 2.5 mm and an inner diameter of 1.3 mm at a flow rate of 10 to 50 mL / min; the soaking time in the coagulant in step one to two is 2 to 6 hours; the high-temperature calcination procedure in step one to two is as follows: first, heat from room temperature to 400 to 500°C and hold for 1 to 3 hours; then heat to 1500 to 1600°C and hold for 1 to 3 hours; then cool down to 500°C and finally allow to cool naturally to room temperature; the heating rate is 2 to 5°C / min; the cooling rate is 2 to 5°C / min. Other steps are the same as in Specific Implementation Methods One to Three.

[0050] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the two ends of the membrane shell 1 mentioned in step two are removable covers 2, and the center of the removable cover 2 is provided with a water outlet 3. The removable cover 2 is connected to the membrane shell 1 by threads 4; the interior of the membrane shell 1 is provided with a titanium metal grid 8 and a counter electrode mesh / plate 9, which are fixed inside the membrane shell 1 by positioning baffles 11 of the titanium metal grid and positioning baffles 12 of the counter electrode mesh / plate, respectively; the nitrogen... The titanium nitride hollow fiber membrane 6 is cut into multiple strands, and the two ends of the cut titanium nitride hollow fiber membrane 6 are fixed and electrically connected by inserting them into the mesh of the titanium nitride grid 8. The multiple titanium nitride hollow fiber membranes 6 are arranged inside the counter electrode mesh / plate 9. The membrane shell 1 is provided with a water inlet 13, a water outlet 3, a connecting wire outlet 5, and a reference electrode outlet 7. The titanium nitride grid 8 and the counter electrode mesh / plate 9 are connected to an external power source through the connecting wires 10 of the titanium nitride grid and the counter electrode mesh / plate. Other steps are the same as in specific embodiments one to four.

[0051] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: in step two, the titanium metal mesh 8 and the counter electrode mesh / plate 9 are fixed inside the membrane shell 1 by the positioning baffles 11 of the titanium metal mesh and 12 of the counter electrode mesh / plate, respectively; the pre-reserved openings 5 ​​for the connecting wires and the gaps connecting the titanium metal mesh 8 are sealed with epoxy resin; the membrane shell 1 and the removable cover 2 are made of polyvinyl chloride, polymethyl methacrylate, or ABS plastic; the counter electrode mesh / plate 9 is a graphite sheet, a platinum sheet, or a titanium mesh with a ruthenium oxide-iridium oxide coating. Other steps are the same as in Specific Implementation Methods One to Five.

[0052] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in the following ways: the palladium salt mentioned in step three ① is sodium tetrachloropalladium; the inorganic bromide mentioned in step three ① is sodium bromide; the sulfate mentioned in step three ① is sodium sulfate; the molar ratio of the palladium salt to the inorganic bromide mentioned in step three ① is 1:(4~10); the concentration of the palladium salt in the electrodeposition solution mentioned in step three ① is 0.05 mmol / L~0.2 mmol / L; the concentration of the sulfate in the electrodeposition solution mentioned in step three ① is 40 mmol / L~60 mmol / L; the concentration of polyvinylpyrrolidone in the electrodeposition solution mentioned in step three ① is 0.1 g / L~0.3 g / L. Other steps are the same as in Specific Implementation Methods One to Six.

[0053] Specific Implementation Method Eight: This implementation method is used to remove trace amounts of halogenated pollutants from water; the halogenated pollutants are organic or inorganic halogenated pollutants; the organic halogenated pollutants are 4-chlorophenol, 4-bromophenol, or 4-iodophenol; the inorganic halogenated pollutants are sodium chlorite or sodium bromate.

[0054] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that it is used to remove trace amounts of halogenated pollutants from water, and is specifically completed according to the following steps:

[0055] Using a palladium-based composite electrocatalytic membrane for removing halogenated contaminants from water as the cathode and a counter electrode mesh / plate 9 as the anode, the palladium-based composite electrocatalytic membrane module for removing halogenated contaminants from water operates in dead-end filtration and constant current or constant potential electrolysis mode; the flux of water containing halogenated contaminants is 50~150 L·m -2 ·h -1 At a current density of 0.05~0.25 mA·cm -2 Under conditions of a potential of -0.1 to -0.3V VS RHE or a module cell voltage of 2.0 to 5.0V, the device operates continuously at constant current or constant potential for 30 to 60 minutes to remove trace amounts of halogen-containing pollutants; the concentration of halogen-containing pollutants in the water is less than 1 mg / L. Other steps are the same as in specific implementation methods one to eight.

[0056] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: after the palladium-based composite electrocatalytic membrane module used to remove halogen-containing pollutants from water has been running for 30-60 minutes, the composite hollow fiber electrocatalytic membrane 6 needs to be cleaned. The method is as follows: apply a reverse voltage to clean the trace amounts of halogen-containing pollutants adhering to the surface and inside the membrane pores of the composite hollow fiber electrocatalytic membrane 6. The applied reverse voltage is 2.5-3.5 V, and the cleaning time is 30-120 s. Other steps are the same as in Specific Implementation Methods One to Nine.

[0057] The beneficial effects of the present invention are verified using the following embodiments:

[0058] Example 1: A method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, specifically comprising the following steps:

[0059] I. Preparation of titanium nitride hollow fiber membranes:

[0060] ① Mix titanium nitride powder with an average particle size of 500 nm, alumina powder with an average particle size of 500 nm, polymethyl methacrylate powder and polyvinylpyrrolidone powder in a certain proportion, then add them to a certain amount of N,N-dimethylacetamide, and ball mill for 18 h to make them evenly mixed. Finally, perform vacuum degassing treatment for 1 h to obtain a uniform casting solution.

[0061] The mass ratio of titanium nitride powder, alumina powder, polymethyl methacrylate powder, polyvinylpyrrolidone powder and N,N-dimethylacetamide mentioned in step 1① is 40:10:10:1:39.

[0062] ② Using water as both internal and external coagulants, the casting solution and the internal coagulant are simultaneously extruded from a spinneret with an outer diameter of 2.5 mm and an inner diameter of 1.3 mm at flow rates of 10 mL / min and 50 mL / min, respectively, to form hollow fibers. The fibers are then soaked in the external coagulant for 2 hours to allow for complete phase transformation. The hollow fibers are then removed from the external coagulant and subjected to shaping and drying. Finally, argon gas is introduced throughout the process, and the fibers are calcined at high temperature in an argon atmosphere to obtain a titanium nitride hollow fiber membrane.

[0063] The high-temperature calcination procedure described in step 1② is as follows: first, raise the temperature from room temperature to 450℃ and hold for 2 hours; then raise the temperature to 1600℃ and hold for 2 hours; then lower the temperature to 500℃ and finally allow it to cool naturally to room temperature; the heating rate is 3℃ / min; the cooling rate is 5℃ / min.

[0064] 2. The titanium nitride hollow fiber membrane is loaded into the membrane module to obtain the membrane module based on the titanium nitride hollow fiber membrane;

[0065] The membrane module based on titanium nitride hollow fiber membrane includes a membrane shell 1, a removable cover 2, an inlet 13, an outlet 3, a thread 4, a connecting wire 5, a titanium nitride hollow fiber membrane 6, a reference electrode 7, a titanium metal grid 8, a counter electrode grid / sheet 9, a connecting wire 10 between the titanium metal grid and the counter electrode grid / sheet, a positioning baffle 11 for the titanium metal grid, and a positioning baffle 12 for the counter electrode grid / sheet.

[0066] III. Loading palladium nanoparticles using a flow-through electrodeposition method:

[0067] ① Preparation of palladium electrodeposition solution:

[0068] Sodium sulfate, sodium tetrachloropalladium, sodium bromide, and polyvinylpyrrolidone were dissolved in water, stirred until homogeneous, and the pH of the system was adjusted to 2.0 to obtain the electrodeposition solution.

[0069] The concentration of sodium bromide in the electrodeposition solution described in step 3① is 1 mmol / L;

[0070] The concentration of sodium tetrachloropalladium in the electrodeposition solution described in step 3① is 0.1 mmol / L;

[0071] The concentration of sodium sulfate in the electrodeposition solution described in step 3① is 50 mmol / L;

[0072] The concentration of polyvinylpyrrolidone in the electrodeposition solution described in step 3① is 0.2 g / L;

[0073] ② Palladium nanoparticles were loaded using a flow-through electrodeposition method:

[0074] In dead-end filtration mode, the membrane module based on titanium nitride hollow fiber membrane is powered on and cyclic voltammetry electrodeposition is performed, with the membrane flux of the electrodeposition solution maintained at 300 L·m⁻¹. -2 ·h -1 The scanning potential range of the cyclic voltammetry is 0.1 to -0.4 V vs RHE, the potential scanning rate is 5 mV / s, and the number of scan cycles is 10.

[0075] ③ Cleaning and drying:

[0076] The electrodeposition solution inside the membrane module was replaced with deionized water at 100 L·m -2 ·h -1 At a membrane flux of 10000, the membrane was filtered for 30 min. After cleaning, it was dried at room temperature. Palladium nanoparticles were loaded onto the surface of titanium nitride hollow fiber membrane 6 to obtain a palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water and a palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water.

[0077] Figure 2 This is a scanning electron microscope image of the cross-sectional structure of the titanium nitride conductive hollow fiber membrane prepared in step one of Example 1;

[0078] from Figure 2 It can be seen that the inner diameter and outer diameter of the titanium nitride conductive hollow fiber membrane are 1.81 mm and 1.56 mm, respectively, and the thickness is 125 μm.

[0079] Application Example 1: Evaluation of the halogen-containing pollutant removal performance of the palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water prepared in Example 1:

[0080] Using 4-chlorophenol, 4-bromophenol, and 4-iodophenol as model organic halogenated pollutants, and sodium chlorite and sodium bromate as model inorganic halogenated pollutants, the removal performance of a composite electrocatalytic membrane for halogenated pollutants was evaluated. Test conditions: 50 mM sodium sulfate solution was used as the electrolyte; dissolved oxygen in the water was removed by purging with pure nitrogen for 30 min beforehand; the initial pollutant concentration was 0.5 mM; the initial pH was adjusted to 7.5; dead-end filtration was used; and the electrolysis potential was -0.16 V vs RHE. First, the removal kinetics of halogenated pollutants were evaluated: the hydraulic residence time within the membrane was adjusted by changing the membrane flux to obtain the pseudo-monovalent reaction rate constant and the critical hydraulic residence time (the shortest water flow residence time required to achieve a halogenated pollutant removal rate of over 90%). The pseudo-monovalent reaction rate constants for 4-chlorophenol, 4-bromophenol, 4-iodophenol, sodium chlorite, and sodium bromate were 88 min. -1 240 min -1 383 min -1 501 min -1 107 min -1 The critical hydraulic residence times were 1.7 s, 1.0 s, 0.7 s, 0.5 s, and 1.5 s, respectively. Taking 4-chlorophenol as an example, the reaction rate constant of the invented palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water is significantly faster than that of traditional electrochemical techniques (0.01~0.1 min). -1 It is 2 to 3 orders of magnitude higher.

[0081] Figure 3 This is a graph showing the performance of the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water in Application Example 1, where C is the value of the membrane. p C represents the concentration of pollutants in the effluent. f This represents the concentration of pollutants in the raw water.

[0082] from Figure 3 It can be seen that when using the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water, the pseudo-monovalent reaction rate constants for 4-chlorophenol, 4-bromophenol, and 4-iodophenol are 88 min. -1 240 min -1 383 min -1 The critical hydraulic residence times were 1.7 s, 1.0 s, and 0.7 s, respectively.

[0083] Figure 4 This is a graph showing the performance of the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water in Application Example 1, where C is the value of the membrane. p C represents the concentration of pollutants in the effluent.f This represents the concentration of pollutants in the raw water.

[0084] from Figure 4 It can be seen that when using the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogenated pollutants from water, the pseudo-monovalent reaction rate constants of sodium chlorite and sodium bromate are 501 min. -1 and 107 min -1 The critical hydraulic residence times are 0.5 s and 1.5 s, respectively.

[0085] Example 2: The difference between this example and Example 1 is that the concentration of sodium bromide in the electrodeposition solution described in step 3① is 0.5 mmol / L. All other steps and parameters are the same as in Example 1.

[0086] Application Example 2: Evaluation of the halogen-containing pollutant removal performance of the palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water prepared in Example 2:

[0087] Using 4-chlorophenol as a model halogenated pollutant, the removal performance of a composite electrocatalytic membrane was evaluated. Test conditions: 50 mM sodium sulfate solution was used as the electrolyte; dissolved oxygen was removed by purging with pure nitrogen for 30 min beforehand; the initial pollutant concentration was 0.5 mM; the initial pH was adjusted to 7.5; dead-end filtration was used; and the electrolysis potential was -0.16 V vs RHE. First, the kinetics of halogenated pollutant removal were evaluated: the hydraulic residence time within the membrane was adjusted by varying the membrane flux to obtain the pseudo-monovalent reaction rate constant and the critical hydraulic residence time (the shortest water flow residence time required to achieve a halogenated pollutant removal rate of over 90%). The pseudo-monovalent reaction rate constant for 4-chlorophenol was 322 min. -1 Compared with traditional electrochemical technology (0.01~0.1 min), -1 The efficiency was 3-4 orders of magnitude higher, with a critical hydraulic retention time of 0.7 s. Then, the stability of pollutant removal was evaluated at 100 L·m⁻¹. -2 ·h -1 The membrane was continuously operated at the specified flux for 60 minutes to observe changes in pollutant removal rate, and no significant decrease was observed.

[0088] Example 3: The difference between this example and Example 1 is that sodium bromide is not added in step 3.1 of this example. Instead, sodium sulfate, sodium tetrachloropalladium, and polyvinylpyrrolidone are dissolved in water, stirred evenly, and the pH of the system is adjusted to 2.0 to obtain the electrodeposition solution. Other steps and parameters are the same as in Example 1.

[0089] Application Example 3: Evaluation of the halogen-containing pollutant removal performance of the palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water prepared in Example 3:

[0090] Using 4-chlorophenol as a model halogenated pollutant, the removal performance and stability of the composite electrocatalytic membrane were evaluated. Test conditions: 50 mM sodium sulfate solution was used as the electrolyte; dissolved oxygen in the water was removed by purging with pure nitrogen for 30 min beforehand; the initial pollutant concentration was 0.5 mM; the initial pH was adjusted to 7.5; dead-end filtration was used; and the electrolysis potential was -0.16 V vs RHE. First, the kinetics of halogenated pollutant removal were evaluated: the hydraulic residence time within the membrane was adjusted by changing the membrane flux to obtain the pseudo-monovalent reaction rate constant and the critical hydraulic residence time (the shortest water flow residence time required to achieve a halogenated pollutant removal rate of over 90%). The pseudo-monovalent reaction rate constant for 4-chlorophenol was 58 min. -1 Compared with traditional electrochemical technology (0.01~0.1 min), -1 The efficiency was 2-3 orders of magnitude higher, with a critical hydraulic retention time of 2.2 s. Then, the stability of pollutant removal was evaluated at 100 L·m⁻¹. -2 ·h -1 The membrane was continuously run for 60 minutes at the specified flux to observe the changes in pollutant removal rate. Compared with the initial removal rate, the removal rate decreased by 59% after 60 minutes of operation.

[0091] Figure 5 High-resolution transmission electron microscopy images of palladium nanoparticles in palladium-based composite electrocatalytic membranes used to remove halogenated pollutants from water in Examples 2 and 3;

[0092] from Figure 5 It can be seen that, compared with Example 2, in Example 3, since sodium bromide was not added during the electrodeposition of palladium, the preferred orientation crystal plane of the deposited palladium nanoparticles is the (100) crystal plane, rather than the (111) crystal plane.

[0093] Figure 6 The images show a structural comparison of the palladium-based composite electrocatalytic membranes used in Examples 2 and 3 for removing halogen-containing pollutants from water. The left column represents Example 2, and the right column represents Example 3. From top to bottom, the images are a cross-sectional scanning electron microscope image, a cross-sectional elemental energy spectrum, and a surface scanning electron microscope image.

[0094] from Figure 6 It can be seen that, compared with Example 2, in Example 3, since sodium bromide was not added during the electrodeposition of palladium, the preferred orientation crystal plane of the deposited palladium nanoparticles is the (100) crystal plane instead of the (111) crystal plane, and the formed palladium catalyst layer is more porous, with the average pore size increasing by about 87%.

[0095] Figure 7 The graphs show the performance of the palladium-based composite electrocatalytic membrane modules prepared in Examples 2 and 3 for removing halogenated pollutants from water in Application Examples 2 and 3, respectively, in removing 4-chlorophenol. Figure C... p C represents the concentration of 4-chlorophenol in the effluent. f This refers to the concentration of 4-chlorophenol in the raw water.

[0096] from Figure 7 It can be seen that the palladium-based composite electrocatalytic membranes prepared in Examples 2 and 3 for removing halogenated pollutants from water exhibit significant differences in reaction kinetics when removing 4-chlorophenol. When using the palladium-based composite electrocatalytic membrane module prepared in Example 2 for removing halogenated pollutants from water, the pseudo-monovalent reaction rate constant for removing 4-chlorophenol is 322 min. -1 The critical hydraulic residence time is 0.7 s. When using the palladium-based composite electrocatalytic membrane module prepared in Example 3 for removing halogenated contaminants from water to remove 4-chlorophenol, the pseudo-monovalent reaction rate constant is 58 min. -1 The critical hydraulic residence time was 2.2 s. Due to the addition of a certain proportion of inorganic bromide during electrodeposition, the palladium-based composite electrocatalytic membrane prepared in Example 2 for removing halogen-containing pollutants from water had a dense palladium layer structure with small and uniform pore size. However, because no inorganic bromide was added during electrodeposition, the palladium-based composite electrocatalytic membrane prepared in Example 3 for removing halogen-containing pollutants from water had a loose palladium layer structure with larger and less uniform pore size. This resulted in the reaction kinetics of the palladium-based composite electrocatalytic membrane prepared in Example 3 for removing halogen-containing pollutants from water being significantly lower than those prepared in Example 2.

[0097] Figure 8 The graph shows the stability of the palladium-based composite electrocatalytic membrane module for removing halogenated pollutants from water prepared in Examples 2 and 3 in Application Examples 2 and 3 for the removal of 4-chlorophenol. The vertical axis of the graph is the percentage decrease in removal rate relative to the initial removal rate at different operating times.

[0098] from Figure 8 It can be seen that the palladium-based composite electrocatalytic membranes prepared in Examples 2 and 3 for removing halogenated pollutants from water exhibit significant differences in anti-poisoning ability and stability when removing 4-chlorophenol. When using the palladium-based composite electrocatalytic membrane module prepared in Example 2 for removing halogenated pollutants from water to remove 4-chlorophenol, at 100 L·m⁻¹… -2 ·h -1 After continuous operation at the membrane flux for 60 min, the removal rate did not decrease significantly. When using the palladium-based composite electrocatalytic membrane module prepared in Example 3 for removing halogenated pollutants from water to remove 4-chlorophenol, the removal rate was [not specified] at 100 L·m⁻¹. -2 ·h -1After continuous operation at the membrane flux for 60 min, the removal rate decreased by 59% compared to the initial removal rate. Due to the addition of a certain proportion of inorganic bromide during the electrodeposition process, the palladium layer crystal orientation of the palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants in water prepared in Example 2 was mainly (111) crystal plane. However, due to the absence of inorganic bromide, the palladium layer crystal orientation of the palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants in water prepared in Example 3 was mainly (100) crystal plane. As a result, the anti-poisoning ability and stability of the palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants in water prepared in Example 3 were significantly lower than those of the palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants in water prepared in Example 2.

[0099] Application Example 4: Evaluation of the performance of the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing trace amounts of halogenated pollutants from drinking water:

[0100] Using 4-chlorophenol as a model halogenated pollutant, the removal efficiency of a composite electrocatalytic membrane for trace halogenated pollutants in drinking water was evaluated. Test conditions: Actual tap water was used as the raw water, with a conductivity of 80 μS / cm, pH of 7.0, total organic carbon content of 4.8 mg / L, and an initial 4-chlorophenol concentration of 250 μg / L; a constant flux dead-end filtration mode was adopted, with the membrane flux maintained at 50 L·m⁻¹. -2 ·h -1 A constant current electrolysis mode was used, with a current density of 0.10 mA / cm². 2 Every 30 minutes of operation, a reverse voltage of 3.0 V was applied for intermittent in-situ electrochemical cleaning for 2 minutes to remove organic matter trapped or adsorbed on the membrane surface, thereby restoring membrane flux and catalytic activity. Over 10 operating cycles, the removal rate of 4-chlorophenol remained above 99.9%, demonstrating good stability. In contrast, under the mode without intermittent in-situ electrochemical cleaning, the removal rate of 4-chlorophenol decreased significantly after 30 minutes of operation, with a decrease of up to 40%. Under these optimal operating conditions, the overall operating energy consumption was 76 Wh / m³. 3 The energy consumed by water infiltration is 33 Wh / m³. 3 The energy consumed by electrolysis is 43 Wh / m³. 3 It is significantly lower than the operating energy consumption of traditional electrochemical water treatment technologies and high-pressure membrane technologies such as nanofiltration and reverse osmosis (>200 Wh / m³). 3 ).

[0101] Figure 9 To illustrate the effect of using the palladium-based composite electrocatalytic membrane module prepared in Example 1 to remove trace amounts of halogenated pollutants from drinking water under different operating modes in Example 4;

[0102] from Figure 9 It can be seen that, under the intermittent in-situ electrochemical cleaning mode, the palladium-based composite electrocatalytic membrane module prepared in Example 1 for removing halogen-containing contaminants from drinking water exhibits significantly improved operational stability. During a continuous 5-hour operation, the removal rate of 4-chlorophenol remained stable without significant decrease. In contrast, under the non-intermittent in-situ electrochemical cleaning mode, the removal rate of 4-chlorophenol decreased significantly after 30 minutes of operation, with a decrease of up to 40%.

Claims

1. A method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, characterized in that... The preparation method is specifically carried out according to the following steps: I. Preparation of titanium nitride hollow fiber membranes: ① Mix titanium nitride powder, alumina powder, polymethyl methacrylate powder and polyvinylpyrrolidone powder in a certain proportion, then add them to a certain amount of organic solvent, ball mill for a certain time to make them evenly mixed, and finally perform vacuum degassing to obtain a uniform casting solution. ② The casting liquid and coagulant are simultaneously extruded from the spinneret to form hollow fibers. The fibers are then soaked in the coagulant for a sufficient time to allow for complete phase transformation. The hollow fibers are then removed from the coagulant, shaped and dried, and finally calcined at high temperature in a nitrogen or argon atmosphere to obtain titanium nitride hollow fiber membrane.

2. The titanium nitride hollow fiber membrane is loaded into the membrane module to obtain the membrane module based on the titanium nitride hollow fiber membrane; The membrane module based on titanium nitride hollow fiber membrane includes a membrane shell (1), a removable cover (2), an inlet (13), an outlet (3), a thread (4), a connecting wire opening (5), a titanium nitride hollow fiber membrane (6), a reference electrode opening (7), a titanium grating (8), a counter electrode mesh / sheet (9), a connecting wire (10) between the titanium grating and the counter electrode mesh / sheet, a positioning baffle (11) for the titanium grating and a positioning baffle (12) for the counter electrode mesh / sheet. III. Loading palladium nanoparticles using a flow-through electrodeposition method: ① Preparation of palladium electrodeposition solution: Sulfate, palladium salt, inorganic bromide, and polyvinylpyrrolidone were dissolved in water, stirred until homogeneous, and the pH of the system was adjusted to 2.0 to obtain the electrodeposition solution. ② Palladium nanoparticles were loaded using a flow-through electrodeposition method: In dead-end filtration mode, the membrane module based on titanium nitride hollow fiber membrane is powered on and cyclic voltammetry electrodeposition is performed, with the membrane flux of the electrodeposition solution maintained at 100–500 L·m⁻¹. -2 ·h -1 The scanning potential range of the cyclic voltammetry is 0.1 to -0.4 V vs RHE, the potential scanning rate is 2 to 10 mV / s, and the number of scan cycles is 2 to 10. ③ Cleaning and drying: The electrodeposition solution inside the membrane module was replaced with deionized water at a concentration of 100–500 L·m⁻¹. -2 ·h -1 At the membrane flux, filtration was performed for 10-30 min. After cleaning, the membrane was dried at room temperature. Palladium nanoparticles were loaded onto the surface of the titanium nitride hollow fiber membrane (6) to obtain a palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water and a palladium-based composite electrocatalytic membrane assembly for removing halogen-containing pollutants from water.

2. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... The mass ratio of titanium nitride powder to alumina powder in step 1① is (80~95):(5~20); the total mass of titanium nitride powder and alumina powder in step 1① accounts for 45~55% of the mass of the casting solution; the mass of polymethyl methacrylate powder in step 1① accounts for 5~15% of the mass of the casting solution; and the mass of polyvinylpyrrolidone powder in step 1① accounts for 0.5~1.5% of the mass of the casting solution.

3. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... The organic solvent mentioned in step 1① is N,N-dimethylacetamide; the ball milling time mentioned in step 1① is 12~24 h; the vacuum degassing time mentioned in step 1① is 30~90 min.

4. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... The coagulant mentioned in step 1② is water; both the casting solution and the coagulant in step 1② are simultaneously extruded from a spinneret with an outer diameter of 2.5 mm and an inner diameter of 1.3 mm at a flow rate of 10~50 mL / min; the soaking time in the coagulant in step 1② is 2~6 h; the high-temperature calcination procedure mentioned in step 1② is as follows: first, heat from room temperature to 400~500℃ and hold for 1~3 h; then heat to 1500~1600℃ and hold for 1~3 h; then cool down to 500℃ and finally cool naturally to room temperature; the heating rate is 2~5 ℃ / min; the cooling rate is 2~5 ℃ / min.

5. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... The membrane housing (1) described in step two has removable covers (2) at both ends. A water outlet (3) is provided at the center of the removable cover (2). The removable cover (2) is connected to the membrane housing (1) by a thread (4). The membrane housing (1) is provided with a titanium metal mesh (8) and a counter electrode mesh / plate (9) inside. The titanium metal mesh (8) and the counter electrode mesh / plate (9) are fixed inside the membrane housing (1) by positioning baffles (11) of the titanium metal mesh and positioning baffles (12) of the counter electrode mesh / plate, respectively. The titanium nitride hollow fiber membrane (6) is cut into Multiple titanium nitride hollow fiber membranes (6) are cut and then fixed and electrically connected at both ends by inserting them into the mesh of the titanium grating (8). The multiple titanium nitride hollow fiber membranes (6) are set inside the counter electrode mesh / sheet (9). The membrane shell (1) is provided with a water inlet (13), a water outlet (3), a connecting wire outlet (5), and a reference electrode outlet (7). The titanium grating (8) and the counter electrode mesh / sheet (9) are connected to an external power source through the connecting wires (10) of the titanium grating and the counter electrode mesh / sheet.

6. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... In step two, the titanium metal mesh (8) and the counter electrode mesh / plate (9) are fixed inside the membrane shell (1) by the positioning baffle (11) of the metal mesh and the positioning baffle (12) of the counter electrode mesh / plate, respectively; the reserved opening (5) for the connecting wire and the gaps for connecting the titanium metal mesh (8) are sealed with epoxy resin; the membrane shell (1) and the removable cover (2) are made of polyvinyl chloride, polymethyl methacrylate or ABS plastic; the counter electrode mesh / plate (9) is a graphite sheet, a platinum sheet or a titanium mesh with a ruthenium oxide-iridium oxide coating.

7. The method for preparing a palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water according to claim 1, characterized in that... The palladium salt mentioned in step 3.① is sodium tetrachloropalladium; the inorganic bromide mentioned in step 3.① is sodium bromide; the sulfate mentioned in step 3.① is sodium sulfate; the molar ratio of the palladium salt to the inorganic bromide mentioned in step 3.① is 1:(4~10); the concentration of the palladium salt in the electrodeposition solution mentioned in step 3.① is 0.05 mmol / L~0.2 mmol / L; the concentration of the sulfate in the electrodeposition solution mentioned in step 3.① is 40 mmol / L~60 mmol / L; the concentration of polyvinylpyrrolidone in the electrodeposition solution mentioned in step 3.① is 0.1 g / L~0.3 g / L.

8. The application of the palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, prepared by the preparation method according to any one of claims 1 to 7, characterized in that... This product is used to remove trace amounts of halogenated pollutants from water; the halogenated pollutants are organic or inorganic; the organic halogenated pollutants are 4-chlorophenol, 4-bromophenol, or 4-iodophenol; and the inorganic halogenated pollutants are sodium chlorite or sodium bromate.

9. The application of the palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, prepared by the method according to claim 8, characterized in that... The process for removing trace amounts of halogenated contaminants from water is accomplished through the following steps: Using a palladium-based composite electrocatalytic membrane for removing halogen-containing pollutants from water as the cathode and a counter electrode mesh / plate (9) as the anode, the palladium-based composite electrocatalytic membrane assembly for removing halogen-containing pollutants from water is operated by dead-end filtration, constant current or constant potential electrolysis; wherein the flux of water containing halogen-containing pollutants is 50~150 L·m -2 ·h -1 At a current density of 0.05~0.25 mA·cm -2 Under the conditions of a potential of -0.1~-0.3V VS RHE or a module cell voltage of 2.0~5.0V, the constant current or constant potential is continuously operated for 30~60 min to achieve the removal of trace amounts of halogen-containing pollutants; the concentration of halogen-containing pollutants in the water is less than 1 mg / L.

10. The application of the palladium-based composite electrocatalytic membrane and its components for removing halogen-containing pollutants from water, prepared by the method according to claim 9, characterized in that... After the palladium-based composite electrocatalytic membrane module for removing halogen-containing pollutants from water has been running for 30 to 60 minutes, the composite hollow fiber electrocatalytic membrane (6) needs to be cleaned. The method is as follows: apply a reverse voltage to clean the surface of the composite hollow fiber electrocatalytic membrane (6) and the trace amount of halogen-containing pollutants attached to the membrane pores. The reverse voltage is 2.5 to 3.5V and the cleaning time is 30 to 120 seconds.

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