Device for water-solid contact electrocatalytic degradation of trace antibiotic by using high charge density nanofiber membrane

Abstract

The application relates to a device for water-solid contact electrocatalytic degradation of trace antibiotics by using a high-charge-density nanofiber membrane, which comprises the following steps: S1, preparing Ti3C2T x MXene nanosheets; S2, preparing Ti3C2T x MXene / DMF spinning solution; S3, preparing high-electronegativity polymer spinning solution, dissolving high-electronegativity polymer powder in DMF and acetone, performing magnetic stirring by using a PTFE stirring rod magnet to perform mixing, and obtaining high-electronegativity polymer spinning solution; S4, mixing Ti3C2T x MXene / DMF spinning solution and the high-electronegativity polymer spinning solution, and then performing spinning, so that a high-charge-density nanofiber membrane is obtained; and S5, assembling the prepared high-charge-density nanofiber membrane into an ultrasonic filtration unit, and then making wastewater containing trace antibiotics and suspended particles enter the ultrasonic wave chamber from a water inlet pipe.

Description

Technical Field

[0001] This invention relates to a device for the electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact. Background Technology

[0002] The efficient removal of antibiotics from the aquatic environment has always been a hot topic and a challenge in modern wastewater treatment technology research.

[0003] Membrane separation is a cutting-edge technology for controlling antibiotics. Nanofiltration, reverse osmosis, and forward osmosis can remove antibiotics by utilizing the small pore size, hydrophobic adsorption of membrane materials, and electrostatic interactions. Membrane filtration coupled with advanced oxidation processes (AOPs) such as ozone catalytic oxidation, Fenton oxidation, electrochemical oxidation, and photocatalytic oxidation can also efficiently remove antibiotics. AOPs remove antibiotics by generating highly oxidizing reactive oxygen species, such as ·OH and SO42-. - · and O2 - • It reacts with antibiotics through redox reactions, degrading them into non-toxic small molecules or mineralizing them.

[0004] Electrospinning is a mature and emerging membrane fabrication method. Under the action of a high-voltage electrostatic field, the prepared nanofiber membrane has a three-dimensional interconnected structure with high porosity and good connectivity. It not only has low membrane impedance and is not easily fouled, but also has the advantages of high water flux and low energy consumption.

[0005] Contact electrocatalysis is a unique catalytic principle. Unlike traditional catalysis, it utilizes surface polarized electrons induced by contact electrolysis to accelerate chemical reactions. Electrons generated from the contact between water and a solid react with oxygen molecules to produce hydroxyl radicals with strong oxidizing power, which oxidize organic matter in the water, thus degrading or mineralizing pollutants. It features mild reaction conditions, low dosage of auxiliary chemicals, and high efficiency and energy saving.

[0006] Traditional wastewater treatment processes struggle to remove antibiotics, and trace amounts of antibiotics discharged with the effluent constitute a significant source of antibiotic pollution in the environment. Membrane separation is a cutting-edge technology for controlling antibiotics; however, the low water flux and high energy consumption of nanofiltration, reverse osmosis, and forward osmosis membrane separation methods limit their application. While traditional microfiltration and ultrafiltration membranes offer high water flux, low filtration pressure, and low energy consumption, antibiotic molecules are generally smaller than the membrane pore size, resulting in poor removal efficiency due to sieving alone. Furthermore, membrane filtration is a purely physical process, involving physical sieving and adsorption, and cannot ultimately degrade antibiotics. During membrane filtration, contaminants continuously accumulate on the surface or within the pores, leading to membrane fouling. Electrospun nanofiber membranes, with their high porosity, highly interconnected three-dimensional structure, offer extremely high water flux and low energy consumption, attracting widespread attention. However, nanofiber membranes typically have micron-sized pores, which cannot remove small molecules like antibiotics through size repulsion. Therefore, there is an urgent need to develop energy-saving, economical, and efficient membrane separation technologies.

[0007] Membrane filtration coupled with advanced oxidation processes (AOPs) such as ozone catalytic oxidation, Fenton oxidation, electrochemical oxidation, and photocatalytic oxidation can efficiently remove antibiotics. However, membrane fouling concentration polarization and the stringent reaction conditions of AOPs significantly increase the cost of antibiotic degradation, and the complex equipment and cumbersome post-treatment limit its large-scale application.

[0008] Existing contact electrocatalysis processes all involve suspending the catalytic material in the wastewater to be treated. As a result, the stirring, ultrasonication, and other operations to disperse the catalytic material consume a lot of energy and are difficult to apply on a large scale. At the same time, the physical size of the contact material, or even its colloidal size, is reduced in order to improve the catalytic efficiency (specific surface area of ​​the contact material), making the subsequent separation and recovery of the contact material from the wastewater a technical bottleneck.

[0009] Based on this, this invention couples electrospun nanofibers with contact electrocatalysis to develop a method for preparing a high-charge-density nanofiber membrane for degrading trace antibiotics based on the principle of contact electrocatalysis. The three-dimensional interconnected structure of the nanofiber membrane not only results in low filtration impedance and high water flux, but also cleverly utilizes its extremely high specific surface area to increase the contact electrocatalytic efficiency between the antibiotic wastewater and the nanofiber membrane. Simultaneously, the introduction of the two-dimensional material MXene to reinforce the nanofiber material further improves the catalytic efficiency. Furthermore, the nanofiber membrane filters and retains colloidal particulate impurities in the water, thereby achieving the simultaneous removal of suspended particles and trace antibiotics from wastewater. Summary of the Invention

[0010] In view of the above-mentioned problems existing in the prior art, the main objective of the present invention is to provide an apparatus for electrocatalytic degradation of trace antibiotics using a water-solid contact of a high charge density nanofiber membrane.

[0011] The technical solution of this invention is as follows:

[0012] An apparatus for the electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact includes the following steps:

[0013] S1. Preparation of Ti3C2T x MXene nanosheets;

[0014] S2, Preparation of Ti3C2T x MXene / N,N-dimethylformamide spinning solution was used to prepare Ti3C2T x MXene nanosheets were dissolved in N,N-dimethylformamide solution at a weight ratio of 1:5 in powder form to obtain Ti3C2T. x MXene / N,N-dimethylformamide spinning solution;

[0015] S3. Prepare a high electronegativity polymer spinning solution by dissolving the high electronegativity polymer powder in N,N-dimethylformamide and acetone, and using a polytetrafluoroethylene stirring rod magnet to perform magnetic stirring for 2.5 hours at a temperature of 70℃ and a rotation speed of 650 rpm to achieve thorough mixing, thereby obtaining a high electronegativity polymer spinning solution.

[0016] S4. The prepared Ti3C2T x A high charge density nanofiber membrane was prepared by mixing MXene / N,N-dimethylformamide spinning solution and a high electronegativity polymer spinning solution, and then by electrospinning the mixed solution.

[0017] S5. The prepared high charge density nanofiber membrane is assembled into the ultrasonic filtration unit. Then, wastewater containing trace amounts of antibiotics and suspended particles enters the ultrasonic chamber through the inlet pipe. After the ultrasonic chamber is filled with wastewater, the power supply of the ultrasonic ceramic plate is turned on. The high-frequency vibration of the ceramic plate causes cavitation bubbles to be generated in the wastewater. From generation to collapse, the cavitation bubbles cause frequent contact between the wastewater and the nanofiber membrane, generating contact electrocatalytic effect to degrade the trace amounts of antibiotics flowing through the membrane pores. At the same time, the nanofiber membrane traps suspended particles, so as to simultaneously achieve antibiotic degradation and suspended particle filtration.

[0018] In step S1, Ti3C2T is prepared. x MXene nanosheets specifically include the following steps:

[0019] S101. Add 0.5-2g of Ti3AlC2 powder to a premixed solution of 0.5-3g of LiF and 3-12M and 10-30mL of HCl, and stir with a polytetrafluoroethylene magnetic stir bar at a speed of 100-500rpm for 12-36 hours, while maintaining the temperature at 20-50℃ to obtain the first mixture.

[0020] S102. The first mixture obtained is washed multiple times with deionized water, and centrifuged at 3500 rpm for 5 minutes each time until a stable dark green supernatant is obtained with a pH value of 6.

[0021] S103. When the pH of the dark green supernatant is 6, the obtained suspension is centrifuged again for 30 minutes, and then sonicated in an ice bath for 1 hour to obtain the second mixture.

[0022] S104. The prepared second mixture is dried in a vacuum oven at 60°C for 12 hours to obtain stable Ti3C2T without liquid stratification. x MXene nanosheets.

[0023] In step S3, the polymer powder is dissolved in DMF and acetone, wherein the mass ratio of the polymer powder, DMF and acetone is 16:33.6:50.4.

[0024] In step 3, the polymer powder is any one of polyvinylidene fluoride powder, polytetrafluoroethylene powder, polychlorotrifluoroethylene powder, or polyvinyl chloride powder.

[0025] The electrospinning method specifically includes the following steps:

[0026] Electrospinning was performed using an electrospinning machine with 21 syringes at a relative humidity of 35%, a voltage of 18kV, a flow rate of 1mL / h, and a height of 15cm.

[0027] High charge density films can also be prepared by a coating method, which specifically includes the following steps:

[0028] Preheat the coating machine to 35℃, pour the mixed solution onto one side of the coating machine, use a 10μm wire rod for coating, run at a speed of 20mm / s, and run at a distance of 300mm from the length of the base film. Push the solution from one side of the film to the other side at a uniform speed, and place it together with the aluminum foil receiving substrate in a 70℃ oven for 30 minutes.

[0029] High charge density membranes can also be prepared by vacuum filtration, which specifically includes the following steps:

[0030] Fix the membrane onto the filtration flask and secure it to the Buchner funnel with a clamp. Turn on the vacuum pump to create a vacuum. Pour the mixed solution into the Buchner funnel. After filtration, place the membrane made from the solution in a 70°C oven to dry for 30 minutes.

[0031] The ultrasonic filtration unit includes an ultrasonic filtration housing, the upper end of which is closed, and the lower end of which has an opening, wherein:

[0032] An inlet is provided on the upper part of one side of the ultrasonic filter housing, and a high charge density nanofiber membrane or a high charge density membrane is horizontally arranged in the upper part of the interior of the ultrasonic filter housing. The inlet is located above the high charge density nanofiber membrane or the high charge density membrane.

[0033] Multiple ultrasonic piezoelectric ceramic sheets are fixedly disposed on the top and lower surface of the ultrasonic filter housing. The ultrasonic piezoelectric ceramic sheets are connected to an external power source through wires. An ultrasonic chamber is formed above the high charge density nanofiber membrane or high charge density membrane.

[0034] It also includes a water inlet pipe, the water outlet of which is fixedly disposed on the outer side wall of the ultrasonic filter housing at the position of the water inlet; the edge of the high charge density nanofiber membrane or high charge density membrane is fixedly connected to the inner side wall of the ultrasonic filter housing.

[0035] This invention has the following advantages and beneficial effects: This patent proposes a method for preparing nanofiber membranes with high charge density. By co-spinning high charge density two-dimensional materials with highly electronegative spinning materials using electrospinning, the prepared nanofiber membranes not only have high water flux but also possess high electronegativity, making them easy to capture electrons. Simultaneously, the introduction of two-dimensional materials such as transition metal carbides, nitrides, or carbonitrides (MXenes) improves the surface potential and electron capture ability of the nanofibers in the membrane, which greatly enhances the efficiency of water-solid contact catalytic degradation of trace antibiotics. Attached Figure Description

[0036] Figure 1 This is a three-dimensional structural diagram of the ultrasonic filtration unit in the device for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in water-solid contact, as provided in an embodiment of the present invention.

[0037] Figure 2 This is a schematic diagram illustrating the mechanism of electrocatalytic degradation of levofloxacin (OFL) using a high charge density nanofiber membrane in a water-solid contact according to an embodiment of the present invention.

[0038] Figure 3 The image shows the actual effect of the electrocatalytic degradation of the antibiotic ciprofloxacin (CIP) by contacting highly electronegative polyvinylidene fluoride (PVDF) and perfluoroethylene propylene copolymer (FEP) powder with water under ultrasonic conditions, as provided in the embodiments of the present invention.

[0039] Figure 4 The image shows the actual effect of the ultrasonic degradation of ciprofloxacin (CIP) by polyvinylidene fluoride (PVDF) nanofiber membrane provided in the embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0041] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0042] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] The present invention will now be further described with reference to the accompanying drawings and specific embodiments.

[0044] like Figures 1 to 4 As shown: The apparatus for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to an embodiment of the present invention includes the following steps:

[0045] S1. Preparation of Ti3C2T x MXene nanosheets;

[0046] S2, configured with Ti3C2T x The MXene / N,N-dimethylformamide (DMF) spinning solution was used to prepare Ti3C2T x MXene nanosheets were dissolved in DMF solution in powder form at a weight ratio of 1:5 to obtain Ti3C2T. x MXene / DMF spinning solution;

[0047] S3. Prepare a high electronegativity polymer spinning solution by dissolving the high electronegativity polymer powder in DMF and acetone, and using a PTFE stirring rod magnet to perform magnetic stirring for 2.5 hours at a temperature of 70℃ and a rotation speed of 650rpm to achieve thorough mixing and obtain the high electronegativity polymer spinning solution.

[0048] S4. The prepared Ti3C2T xA high charge density nanofiber membrane was prepared by mixing MXene / DMF spinning solution and a high electronegativity polymer spinning solution, and then electrospinning the mixed solution.

[0049] S5. The prepared high charge density nanofiber membrane is assembled into the ultrasonic filtration unit. Then, wastewater containing trace amounts of antibiotics and suspended particles enters the ultrasonic chamber through the inlet pipe. After the ultrasonic chamber is filled with wastewater, the power supply of the ultrasonic ceramic plate is turned on. The high-frequency vibration of the ceramic plate causes cavitation bubbles to be generated in the wastewater. From generation to collapse, the cavitation bubbles cause frequent contact between the wastewater and the nanofiber membrane, generating contact electrocatalytic effect to degrade the trace amounts of antibiotics flowing through the membrane pores. At the same time, the nanofiber membrane traps suspended particles, so as to simultaneously achieve antibiotic degradation and suspended particle filtration.

[0050] In step S1, Ti3C2T is prepared. x MXene nanosheets specifically include the following steps:

[0051] S101. Add 0.5-2g of Ti3AlC2 powder to a premixed solution of 0.5-3g of LiF and 3-12M and 10-30mL of HCl. Stir with a PTFE magnetic stir bar at a speed of 100-500rpm for 12-36 hours, while maintaining the temperature at 20-50℃, to obtain the first mixture.

[0052] S102. The first mixture obtained is washed multiple times with deionized water, and centrifuged at 3500 rpm for 5 minutes each time until a stable dark green supernatant is obtained with a pH value of 6.

[0053] S103. When the pH of the dark green supernatant is 6, the obtained suspension is centrifuged again for 30 minutes, and then sonicated in an ice bath for 1 hour to obtain the second mixture.

[0054] S104. The prepared second mixture is dried in a vacuum oven at 60°C for 12 hours to obtain stable Ti3C2T without liquid stratification. x MXene nanosheets.

[0055] In step S3, the polymer powder is dissolved in DMF and acetone, wherein the mass ratio of the polymer powder, DMF and acetone is 16:33.6:50.4.

[0056] In step 3, the polymer powder is any one of polyvinylidene fluoride (PVDF) powder, polytetrafluoroethylene (PTFE) powder, polychlorotrifluoroethylene (PCTFE) powder, or polyvinyl chloride (PVC) powder.

[0057] The preparation of high charge density nanofiber membranes by electrospinning includes the following steps:

[0058] Electrospinning was performed using an electrospinning machine with 21 syringes at a relative humidity of 35%, a voltage of 18kV, a flow rate of 1mL / h, and a height of 15cm.

[0059] High charge density films can also be prepared by a coating method, which specifically includes the following steps:

[0060] Preheat the coating machine to 35℃, pour the mixed solution onto one side of the coating machine, use a 10μm wire rod for coating, run at a speed of 20mm / s, and run at a distance of 300mm from the length of the base film. Push the solution from one side of the film to the other side at a uniform speed, and place it together with the aluminum foil receiving substrate in a 70℃ oven for 30 minutes.

[0061] High charge density membranes can also be prepared by vacuum filtration, which specifically includes the following steps:

[0062] Fix the membrane onto the filtration flask and secure it to the Buchner funnel with a clamp. Turn on the vacuum pump to create a vacuum. Pour the mixed solution into the Buchner funnel. After filtration, place the membrane made from the solution in a 70°C oven to dry for 30 minutes.

[0063] like Figure 1 As shown, the ultrasonic filtration unit 100 includes an ultrasonic filtration housing 101, the upper end of which is closed, and the lower end of which has an opening 107, wherein:

[0064] An inlet 106 is provided on the upper part of one side of the ultrasonic filter housing 101. A high charge density nanofiber membrane 102 or a high charge density membrane is horizontally arranged at the upper end of the interior of the ultrasonic filter housing 101. The inlet 106 is located above the high charge density nanofiber membrane 102 or the high charge density membrane.

[0065] Multiple ultrasonic piezoelectric ceramic sheets 104 are fixedly disposed on the top lower surface of the ultrasonic filter housing 101. The ultrasonic piezoelectric ceramic sheets 104 are connected to an external power line 105 through a wire, and then connected to an external power source through the power line 105. An ultrasonic chamber 103 is formed above the high charge density nanofiber membrane 102 or the high charge density membrane.

[0066] The ultrasonic filtration unit 100 also includes a water inlet pipe 108, the water outlet of which is fixedly disposed on the outer side wall of the ultrasonic filtration housing 101 at the position of the water inlet 106; the edge of the high charge density nanofiber membrane 102 or the high charge density membrane is fixedly connected to the inner side wall of the ultrasonic filtration housing 101.

[0067] Key advantages of this patent:

[0068] 1. During membrane filtration, antibiotic wastewater comes into contact with the surface of the nanofiber membrane pores. This contact electrocatalysis process takes place within the membrane pores. The electron transfer generated by the water-nanofiber contact forms strong oxidizing hydroxyl radicals that degrade trace antibiotic molecules flowing through the membrane pores, thereby completely eliminating antibiotics during membrane filtration.

[0069] 2. The hydroxyl radicals generated during the electrocatalytic process of water-nanofiber contact can also degrade organic pollutants in the membrane filtration process, so this patent can mitigate membrane fouling.

[0070] 3. The three-dimensional interconnected structure of nanofiber membranes can greatly reduce water flow resistance and retain pollutants, thus achieving the dual effects of highly efficient pollutant filtration and retention and trace antibiotic degradation.

[0071] 4. During the membrane filtration process, trace amounts of antibiotics can be degraded simply by the action of ultrasound, without the need to add a catalyst, which greatly reduces costs. Moreover, the device is relatively simple and requires no subsequent treatment.

[0072] 5. Contact electrocatalytic degradation of trace antibiotics occurs within the membrane pores without the need for additional catalysts, thus fundamentally solving the problem of separating and recovering catalytic materials from wastewater.

[0073] 6. Traditional filtration and separation membranes are designed and prepared based on the principles of physical sieving or charge action. This patent designs and prepares filtration and separation membranes from the perspective of enhancing the charge density of the membrane pore surface material. Through the application of highly electronegative polymer spinning materials and two-dimensional modification materials, the ability of nanofibers to capture electrons is greatly enhanced.

[0074] The preparation steps for high charge density nanofiber membranes are as follows:

[0075] Step 1: Ti3C2T xSynthesis of MXene nanosheets. First, 1 g of Ti3AlC2 powder was slowly added to a premixed solution of LiF (1 g) and 9 M HCl (20 mL), and stirred at 350 rpm for 24 hours with a PTFE magnetic stir bar, maintaining the temperature at 35 °C. The resulting mixture was washed with deionized water for several cycles, centrifuged at 3500 rpm for 5 minutes in each cycle. Washing was repeated until a stable dark green supernatant (pH ~ 6) was obtained. Once the pH reached 6, the obtained suspension was centrifuged again for 30 minutes, and then sonicated for 1 hour in an ice bath to separate the layers. The synthesized mixture was dried in a vacuum oven at 60 °C for 12 hours to obtain a stable, liquid-free MXene powder.

[0076] Step 2: Collect Ti3C2T x MXene nanosheets were dissolved in DMF in powder form at a weight ratio of 1:5.

[0077] Steps one and two aim to introduce the two-dimensional material MXene into the nanofiber membrane, thereby increasing the surface potential and electron capture capacity of the nanofibers, improving the hydrophilicity and hydrophobicity of the membrane surface to enhance water flux, and enhancing the electrocatalytic effect of the water-nanofiber surface contact due to fiber surface roughness. The high charge density two-dimensional material is not limited to MXene; other two-dimensional materials such as graphene oxide and carbon nanotubes can also be added to the nanofiber membrane to increase charge density and membrane hydrophilicity.

[0078] Step 3: Preparation of PVDF / DMF / acetone spinning solution. Dissolve PVDF powder in DMF and acetone at a mass ratio of 1:2.1:3.15 (16:33.6:50.4 by mass). Mix thoroughly using a PTFE stirring rod magnet at 70°C and 650 rpm for 2.5 hours.

[0079] The spinning solution determines the basic properties of the membrane, hence the selection of polymer spinning materials. The selection of nanofiber membrane materials is not limited to PVDF; any polymer spinning material with strong electron absorption capacity is suitable. The electron absorption capacity of the spinning material is related to the type of functional group in its side chain. PVDF is a fluorine-containing polymer material in which two hydrogen atoms on its monomer are replaced by two fluorine atoms. Therefore, PVDF has a high charge density when in contact with water due to the strong electron absorption capacity of fluorine. Besides PVDF, PTFE is also a fluorine-containing highly electronegative material, in which all hydrogen atoms on its monomer are replaced by fluorine atoms, so PTFE has a stronger electron absorption capacity than PVDF. Other materials include PCTFE and PVC. Simultaneously, the appropriate fiber solvent is selected, and the material ratio and optimal conditions of the casting solution are optimized.

[0080] Step 4: Mix the obtained MXene / DMF spinning solution with the PVDF / DMF / acetone spinning solution. Under constant electrophysiological conditions, electrospin the mixed spinning solution using a 21-syringe at a relative humidity of 35%, at 18kV, 1mL / h, and a height of 15cm to obtain nanofiber membranes of approximately equal thickness. The nanofiber membranes collected on the aluminum foil should be dried in an oven at 35℃ for 12 hours before use.

[0081] By following the above steps, Ti3C2T can be obtained. x High charge density nanofiber membranes prepared by co-spinning MXene and PVDF.

[0082] It is worth noting that steps three and four aim to introduce MXene into the PVDF nanofiber membrane through electrospinning to create a high charge density nanofiber membrane for filtration and degradation applications. In addition, other membrane modification methods that can combine MXene with PVDF can also be used, such as coating, filtration, and hot pressing. This invention patent describes high charge density membranes prepared by coating and filtration methods for filtration and degradation applications. The specific operation methods are as follows: (1) Coating method: Preheat the coating machine to 35°C to prevent the casting solution from solidifying too quickly. Pour the PVDF / MXene mixed casting solution (see step four) onto one side of the coating machine. Use a 10μm wire rod for coating. The running speed is 20mm / s and the running distance is 300mm of the base membrane length. Push the mixture from one side of the membrane to the other side at a uniform speed and place it in a 70°C oven for 30min together with the aluminum foil receiving substrate. (2) Vacuum filtration method: Fix the membrane on the vacuum filtration flask and secure it to the Buchner funnel with a clamp. Turn on the vacuum pump to create a vacuum and pour the MXene / PVDF mixture into the Buchner funnel. After filtration, place the membrane made from the mixture in a 70°C oven for 30 minutes. Through the above steps, a high charge density membrane is prepared by the coating method and the vacuum filtration method.

[0083] The prepared high-charge-density nanofiber membrane or high-charge-density membrane is assembled onto, for example... Figure 1 In the ultrasonic filtration unit 100 shown, wastewater containing trace amounts of antibiotics and suspended particles enters the ultrasonic chamber through the inlet pipe 108. After the ultrasonic chamber is filled with wastewater, the power supply to the ultrasonic ceramic plate is turned on. The high-frequency vibration of the ceramic plate causes cavitation bubbles to be generated in the wastewater. From generation to collapse, the cavitation bubbles cause frequent contact and electrification between the water and the high-charge-density nanofiber membrane or high-charge-density membrane. This generates a contact electrocatalytic effect that degrades the trace amounts of antibiotics flowing through the membrane pores. At the same time, the high-charge-density nanofiber membrane or high-charge-density membrane traps suspended particles, achieving the dual effects of antibiotic degradation and suspended particle filtration.

[0084] This invention has the following characteristics:

[0085] 1. Revolutionary Application: The high charge density nanofiber membrane possesses a three-dimensional interconnected structure, significantly reducing water flow resistance and effectively intercepting pollutants. Simultaneously, during membrane filtration, the contact between wastewater and the fiber surface within the nanofiber membrane pores generates electron transfer, forming strong oxidizing hydroxyl radicals that degrade trace antibiotic molecules flowing through the membrane pores. This revolutionizes traditional catalysis applications, achieving a dual-purpose membrane.

[0086] 2. Inhibition of membrane fouling. Under the action of ultrasound, the high charge density nanofiber membrane frequently comes into contact with water, inducing electron transfer. The generated hydroxyl radicals can not only degrade trace amounts of antibiotics but also other organic pollutants in the water. Therefore, this membrane has a "self-cleaning" ability and can inhibit membrane fouling.

[0087] 3. Simple operation and low cost. In traditional catalysis, after adding the catalytic material to the wastewater, stirring and ultrasonication are still required, which consumes a lot of energy and is difficult to apply on a large scale. High charge density nanofiber membranes only require the addition of ultrasound during the membrane filtration process to achieve the requirement of degrading trace antibiotics.

[0088] 4. No post-treatment required. Conventional membrane filtration processes such as nanofiltration, reverse osmosis, and forward osmosis only retain trace amounts of antibiotic molecules and cannot completely remove them, requiring further treatment of the retentate. While traditional catalysis can degrade antibiotics, the subsequent separation and recovery of the catalytic material from the wastewater remains a challenge. High charge density nanofiber membranes eliminate the need for post-treatment, thus solving both of these problems.

[0089] 5. Membrane Technology Innovation. Traditional filtration membranes are designed and fabricated based on the principles of physical sieving or charge action. High charge density nanofiber membranes, starting from the perspective of enhancing the charge density of the membrane pore surface material, greatly enhance the electron capture ability of the nanofiber surface through the application of highly electronegative polymer spinning materials and two-dimensional modification materials, providing a completely new design concept for membrane filtration.

[0090] Example 1

[0091] Using a membrane filtration device, PVDF / MXene nanofiber membranes prepared by electrospinning were used to degrade wastewater containing trace amounts of antibiotics (e.g., levofloxacin, OFL) under ultrasonic irradiation. Figure 2As shown, the PVDF / MXene nanofiber membrane first traps pollutants larger than the membrane pore size in the wastewater. Then, under ultrasonic stimulation, the wastewater generates cavitation bubbles. The collapse of these cavitation bubbles leads to frequent contact and charging at the fiber-water interface within the membrane pores. During this charging process, on one hand, single-electron transfer between water and fibers leads to the formation of hydroxyl radicals; on the other hand, electrons accumulated in the membrane pores are captured by O2, forming superoxide radicals, which subsequently form hydroxyl radicals through a chain reaction. The hydroxyl radicals generated from the water-solid contact during membrane filtration then undergo a redox reaction with OFL in the wastewater, degrading it into water, carbon dioxide, and nitrogen.

[0092] Example 2

[0093] PVDF is prone to membrane fouling due to its hydrophobicity. MXene, with its hydrophilic functional groups, can mitigate this problem. MXene can also be replaced with graphene oxide (GO), which also possesses hydrophilic properties. The fabrication process is as follows: 20 wt% PVDF powder and 0.1 wt% GO powder are added to DMF and acetone to prepare an electrospinning solution. The solution is sonicated for 1 hour, and a PVDF / GO composite nanofiber membrane is prepared by electrospinning. The prepared solution is injected into a 5 mL syringe using a 22-gauge needle. The syringe is held vertically for 30 minutes, and the tip is pushed to completely expel air. The electrospinning conditions are: flow rate 0.6 mL / h, voltage 15 kV, TCD (distance from needle tip to collector) 10 cm, duration 6 h, and relative humidity 20–40%. During solvent evaporation, PVDF and GO phases separate to form composite nanofibers.

[0094] Besides GO, carbon nanotubes (CNTs) can also be added to PVDF. The preparation steps are as follows: PVDF powder is dissolved in acetone and DMF organic solvent and stirred continuously at room temperature for 10 hours to obtain a PVDF spinning solution. CNTs are added to PVDF. To ensure uniform dispersion of CNTs in the solution, the solution is first magnetically stirred for 5 hours, then ultrasonically dispersed for 2 hours, and finally nanofibers are deposited by electrospinning. The flow rate is 0.2 mL / h, the voltage is 15 kV, and the TCD is 15 cm.

[0095] Example 3

[0096] High charge-density nanofiber membranes trap suspended particles in the feed water during operation. Without ultrasound, these particles accumulate on the membrane surface and within the pores, causing a decrease in water flux. Under ultrasound, numerous tiny bubbles (cavitation nuclei) in the feed water vibrate and grow into cavitation bubbles. The formation, growth, and collapse of these cavitation bubbles continuously flush away suspended particles, preventing their accumulation on the membrane surface. Simultaneously, the cavitation bubbles lead to frequent water-nanofiber contact, where hydroxyl radicals generated by electrocatalysis degrade suspended particles within the pores, causing them to detach. Therefore, under ultrasound, this high charge-density nanofiber membrane can inhibit membrane fouling.

[0097] Example 4

[0098] The effect of ultrasonic treatment on the electrocatalytic degradation of the antibiotic ciprofloxacin (CIP) by contacting highly electronegative PVDF and perfluoroethylene propylene copolymer (FEP) powders with water. First, a 4 mg / L CIP aqueous solution was prepared. 100 mg of PVDF and FEP powder were added separately to 50 mL of the 4 mg / L CIP solution. The solutions containing PVDF or FEP powder were then ultrasonically treated (ultrasonic parameters: 40 kHz, 100 W) for 5 hours. The ratio (C / C0) of the CIP concentration C in the aqueous solution during the ultrasonic treatment to the initial CIP concentration C0 was recorded. Figure 3 As shown in the figure, after 5 hours of sonication, the removal rates of CIP by electrocatalytic degradation in water by FEP and PVDF powders reached 100% and 80%, respectively, while in the control group without the addition of highly electronegative powder, CIP was almost not degraded. Due to its high electronegativity, FEP has a better ability to degrade CIP than PVDF. This example demonstrates that water-solid contact electrocatalytic degradation of trace antibiotics can be achieved using highly electronegative materials.

[0099] Example 5

[0100] The effect of PVDF nanofiber membrane on CIP degradation under ultrasound was investigated. 15 mL of DMF and 10 mL of acetone (volume ratio 3:2) were pipetted into beakers, and then PVDF powder (12% of the total mass of the spinning solution) was added to the beakers. The mixture was stirred with a PTFE stir bar in a 70℃ water bath until the liquid became clear and transparent, preparing a 12wt% PVDF spinning solution. The electrospinning equipment was set to a voltage of 12 kV, a No. 21 spinning needle, a needle-to-receiving roller distance of 15 cm, a roller speed of 250 rpm / min, a spinning solution volume of 10 mL, and a spinning solution feed rate of 0.8 mL / h. Electrospinning was performed at a temperature of 20℃ and a humidity of 26%.

[0101] The PVDF nanofiber membranes produced by spinning were cut into 60cm pieces.2 80cm 2 100cm 2 120cm 2 260cm 2 The membrane was placed in 50 mL of a 1 mg / L CIP aqueous solution and sonicated (ultrasound parameters: 40 kHz, 100 W) for 6 hours. The CIP concentration ratio (C / CO) in the aqueous solution after sonication was compared with that before sonication. Figure 4 As shown. 60cm 2 80cm 2 100cm 2 120cm 2 260cm 2 The PVDF nanofiber membranes exhibited degradation efficiencies of 6%, 5%, 18%, 17%, and 42% for CIP, respectively, while the control group without PVDF nanofiber membranes showed a degradation efficiency of 7%. Among these, the 60cm... 2 and 80cm 2 The PVDF nanofiber membrane was comparable to the control group, meaning it showed almost no degradation effect at 260 cm⁻¹. 2 The PVDF nanofiber membrane achieved a degradation efficiency of up to 42%. This example demonstrates that the PVDF nanofiber membrane can degrade the antibiotic CIP under water-solid contact electrocatalysis, and the degradation rate increases with the increase of membrane area.

[0102] Example 6

[0103] The effect of FEP nanofiber membrane on CIP degradation under ultrasound was investigated. 14g of ultrapure water and 1g of polyvinyl alcohol (PVA) were weighed out. PVA was added to the water while slowly stirring until a PVA aqueous solution was formed. Then, 12g of FEP dispersion (50wt%) was weighed out and added to the PVA aqueous solution, and the mixture was stirred overnight. Finally, a spinning solution with an FEP to PVA mass ratio of 6:1 was prepared. The electrospinning equipment was set to a voltage of 20kV, a No. 23 spinning needle, a needle-to-receiving roller distance of 15cm, a roller speed of 1000rpm / min, a spinning solution volume of 5mL, and a spinning solution feed rate of 0.3mL / h. Electrospinning was performed at a temperature of 20℃ and a humidity of 21%.

[0104] The spun FEP / PVA nanofiber membrane was dried overnight in an oven at 60°C. The dried FEP / PVA nanofiber membrane was then laid flat on aluminum foil and sintered in a muffle furnace. The heating rate of the muffle furnace was set to 5°C / min, reaching 265°C, and sintering for 10 minutes, after which it was allowed to cool naturally to room temperature. Due to the high-temperature sintering, the PVA thermally decomposed, while the FEP melted and adhered together along the nanofiber shape. The sintered FEP nanofiber membrane was then immersed in water and ultrasonically washed to remove residual PVA from the nanofibers, thus obtaining the FEP nanofiber membrane. Because FEP has a higher electronegativity than PVDF, experimental results confirmed that the FEP nanofiber membrane exhibited higher degradation efficiency for CIP than the PVDF nanofiber membrane.

[0105] The high electronegativity polymer spinning materials described in this patent are not limited to PVDF and FEP; other materials with high electronegativity can also be used, such as polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE), and polyvinyl chloride (PVC). In addition to MXene, two-dimensional modification materials can also incorporate graphene oxide (GO) and carbon nanotubes (CNTs).

[0106] The nanofiber membrane preparation methods described in this patent include, but are not limited to, forming nanofibers by electrospinning. All solution spinning methods that can solidify polymer solutions to form polymer fibers are within the scope of protection of this patent.

[0107] The high charge density nanofiber membrane described in this patent can not only degrade trace amounts of antibiotics, but also degrade other organic pollutants. Therefore, the membrane's function of mitigating membrane fouling is also within the scope of protection of this patent.

[0108] The ultrasonic filtration unit described in this patent is key to the high charge density nanofiber membrane's ability to degrade antibiotics and trap suspended particles; therefore, the ultrasonic filtration unit is also within the scope of protection of this patent.

[0109] This patent proposes a method for preparing nanofiber membranes with high charge density. By co-spinning a high charge density two-dimensional material with a high electronegativity spinning material using electrospinning, the prepared nanofiber membrane not only has high water flux but also exhibits high electronegativity, making it easy to capture electrons. Simultaneously, the introduction of two-dimensional materials such as MXene improves the surface potential and electron-capturing ability of the nanofibers in the membrane, which greatly enhances the efficiency of water-solid contact catalytic degradation of trace antibiotics.

[0110] This patent discloses a filter unit with an ultrasonic device. The ultrasonic device consists of ultrasonic ceramic plates integrated into the top cover of the filter unit. When the ultrasonic filter unit is in operation, the ceramic plates come into contact with water to generate cavitation bubbles. These cavitation bubbles then come into contact with the nanofiber membrane, resulting in frequent electron transfer between water and nanofibers, thereby generating hydroxyl radicals that degrade trace amounts of antibiotics.

[0111] Finally, it should be noted that the above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact, characterized in that, Includes the following steps: S1. Preparation of Ti3C2T x MXene nanosheets; S2, Preparation of Ti3C2T x MXene / N,N-dimethylformamide spinning solution was used to prepare Ti3C2T x MXene nanosheets were dissolved in N,N-dimethylformamide solution at a weight ratio of 1:5 in powder form to obtain Ti3C2T. x MXene / N,N-dimethylformamide spinning solution; S3. Prepare a high electronegativity polymer spinning solution by dissolving the high electronegativity polymer powder in N,N-dimethylformamide and acetone, and using a polytetrafluoroethylene stirring rod magnet to perform magnetic stirring for 2.5 hours at a temperature of 70℃ and a rotation speed of 650 rpm to achieve thorough mixing, thereby obtaining a high electronegativity polymer spinning solution. S4. The prepared Ti3C2T x A high charge density nanofiber membrane was prepared by mixing MXene / N,N-dimethylformamide spinning solution and a high electronegativity polymer spinning solution, and then by electrospinning the mixed solution. S5. The prepared high charge density nanofiber membrane is assembled into the ultrasonic filtration unit. Then, wastewater containing trace amounts of antibiotics and suspended particles enters the ultrasonic chamber through the inlet pipe. After the ultrasonic chamber is filled with wastewater, the power supply of the ultrasonic ceramic plate is turned on. The high-frequency vibration of the ceramic plate causes cavitation bubbles to be generated in the wastewater. From generation to collapse, the cavitation bubbles cause frequent contact between the wastewater and the nanofiber membrane, generating contact electrocatalytic effect to degrade the trace amounts of antibiotics flowing through the membrane pores. At the same time, the nanofiber membrane traps suspended particles, so as to simultaneously achieve antibiotic degradation and suspended particle filtration.

2. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, In step S1, Ti3C2T is prepared. x MXene nanosheets specifically include the following steps: S101. Add 0.5-2g of Ti3AlC2 powder to a premixed solution of 0.5-3g of LiF and 3-12M and 10-30mL of HCl, and stir with a polytetrafluoroethylene magnetic stir bar at a speed of 100-500rpm for 12-36 hours, while maintaining the temperature at 20-50℃ to obtain the first mixture. S102. The first mixture obtained is washed multiple times with deionized water, and centrifuged at 3500 rpm for 5 minutes each time until a stable dark green supernatant is obtained with a pH value of 6. S103. When the pH of the dark green supernatant is 6, the obtained suspension is centrifuged again for 30 minutes, and then sonicated in an ice bath for 1 hour to obtain the second mixture. S104. The prepared second mixture is dried in a vacuum oven at 60°C for 12 hours to obtain stable Ti3C2T without liquid stratification. x MXene nanosheets.

3. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, In step S3, the polymer powder is dissolved in N,N-dimethylformamide and acetone, wherein the mass ratio of the polymer powder, N,N-dimethylformamide and acetone is 16:33.6:50.

4.

4. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, In step 3, the polymer powder is any one of polyvinylidene fluoride powder, polytetrafluoroethylene powder, polychlorotrifluoroethylene powder, or polyvinyl chloride powder.

5. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, The electrospinning method specifically includes the following steps: Electrospinning was performed using an electrospinning machine with 21 syringes at a relative humidity of 35%, a voltage of 18kV, a flow rate of 1mL / h, and a height of 15cm.

6. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, The high charge density membrane is prepared by replacing the high charge density nanofiber membrane with a high charge density membrane and then using a coating method. The coating method specifically includes the following steps: Preheat the coating machine to 35℃, pour the mixed solution onto one side of the coating machine, use a 10 μm wire rod for coating, run at a speed of 20 mm / s, and run at a distance of 300 mm from the length of the base film. Push the mixed solution from one side of the film to the other side at a uniform speed, and place it together with the aluminum foil receiving substrate in a 70℃ oven for 30 min.

7. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, characterized in that, A high charge density membrane is prepared by replacing the high charge density nanofiber membrane with a high charge density membrane and then using a vacuum filtration method. The vacuum filtration method specifically includes the following steps: Fix the membrane onto the filtration flask and secure it to the Buchner funnel with a clamp. Turn on the vacuum pump to create a vacuum. Pour the mixed solution into the Buchner funnel. After filtration, place the membrane made from the mixed solution in a 70°C oven to dry for 30 minutes.

8. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 1, 6, or 7, characterized in that, The ultrasonic filtration unit includes an ultrasonic filtration housing, the upper end of which is closed, and the lower end of which has an opening, wherein: An inlet is provided on the upper part of one side of the ultrasonic filter housing, and a high charge density nanofiber membrane or a high charge density membrane is horizontally arranged in the upper part of the interior of the ultrasonic filter housing. The inlet is located above the high charge density nanofiber membrane or the high charge density membrane. Multiple ultrasonic piezoelectric ceramic sheets are fixedly disposed on the top and lower surface of the ultrasonic filter housing. The ultrasonic piezoelectric ceramic sheets are connected to an external power source through wires. An ultrasonic chamber is formed above the high charge density nanofiber membrane or high charge density membrane.

9. The method for electrocatalytic degradation of trace antibiotics using a high charge density nanofiber membrane in a water-solid contact according to claim 8, characterized in that, It also includes a water inlet pipe, the water outlet of which is fixedly disposed on the outer wall of the ultrasonic filter housing at the position of the water inlet. The edge of the high charge density nanofiber membrane or high charge density membrane is fixedly connected to the inner wall of the ultrasonic filter housing.

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