Electro-catalytic membrane, electro-catalytic membrane system and preparation method and application of electro-catalytic membrane system

Abstract

The invention belongs to the technical field of membrane materials, and particularly relates to an electro-catalysis membrane, an electro-catalysis membrane system and a preparation method and application of the electro-catalysis membrane. The electro-catalysis membrane comprises a carbon fiber basement membrane and a polyvinylidene fluoride membrane compounded on the carbon fiber basement membrane; co-coated NC magnetic nanoparticles are directionally enriched and distributed on the surface of the polyvinylidene fluoride membrane based on magnetic field induction. The electro-catalytic membrane is directionally enriched and distributed on the surface of a polyvinylidene fluoride membrane based on magnetic induction Co-coated NC nanoparticles, and high-density active sites are formed; co2 + / Co3 + circulation is further accelerated under the action of the electric field, the catalytic efficiency is effectively improved, and efficient PMS activation and synchronous removal of pollutants are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane materials, and particularly relates to an electrocatalytic membrane, an electrocatalytic membrane system, and a preparation method and application thereof. Background Art

[0002] Due to the widespread presence of antibiotics and their difficult-to-degrade biological inertness, traditional water treatment technologies (such as activated sludge, adsorption, and biofiltration) are unable to effectively remove them. Therefore, the development of efficient, green, and sustainable antibiotic wastewater treatment technologies has become a research focus in the current water treatment field.

[0003] Electrochemical membrane technology, owing to its combined membrane separation and electrocatalytic capabilities, has garnered widespread attention in recent years for the treatment of refractory organic pollutants. This technology demonstrates significant potential for in-situ activation of oxidants and continuous generation of free radicals during the filtration process, enabling simultaneous pollutant retention and efficient degradation. However, the powdered catalysts used in existing electrochemical membranes suffer from poor reusability and low mass transfer efficiency, limiting the efficient and continuous activation of peroxymonosulfate (PMS) in antibiotic wastewater.

[0004] Therefore, existing electrochemical membranes still need to be improved. Summary of the Invention

[0005] The purpose of the present invention is to provide an electrocatalytic membrane, an electrocatalytic membrane system, a preparation method and application thereof. The electrocatalytic membrane (Co@NC / PVDF / CP) of the present invention is based on magnetic induction of Co@NC nanoparticles to achieve their directional enrichment and distribution on the surface of the polyvinylidene fluoride membrane, forming high-density active sites; the electric field further accelerates the Co@NC nanoparticles to form a high-density active site. 2+ / Co 3+ The cycle effectively improves the catalytic efficiency and realizes efficient PMS activation and simultaneous removal of pollutants.

[0006] A first aspect of the present invention provides an electrocatalytic membrane, which includes a carbon fiber base membrane and a polyvinylidene fluoride membrane composited on the carbon fiber base membrane, and the surface of the polyvinylidene fluoride membrane is enriched and distributed with Co@NC magnetic nanoparticles based on magnetic field induction.

[0007] In some embodiments of the present invention, the particle size of the Co@NC magnetic nanoparticles is 0.3 μm to 1.2 μm.

[0008] In some embodiments of the present invention, the carbon fiber base film comprises carbon paper.

[0009] The second aspect of the present invention also provides a method for preparing the electrocatalytic membrane described in the first aspect, the preparation method comprising the following steps: preparing CoCo-PBA nanoparticles using potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate as raw materials; coating polydopamine on the surface of the CoCo-PBA nanoparticles by oxidative self-polymerization, and calcining in a protective atmosphere, washing and drying the calcined product to obtain Co@NC magnetic nanoparticles; preparing a casting solution using the Co@NC magnetic nanoparticles, N,N-dimethylformamide, polyvinylidene fluoride and conductive multi-walled carbon nanotubes, uniformly coating the casting solution on one side of the carbon fiber material to form a casting solution, and inducing the distribution of the Co@NC magnetic nanoparticles to the surface by magnetic attraction, and then placing the entirety in deionized water to obtain the electrocatalytic membrane.

[0010] In some embodiments of the present invention, in the preparation of the CoCo-PBA nanoparticles, the molar ratio of the potassium cobalt hydride, the cobalt chloride hexahydrate and the sodium citrate is 4:3:5.

[0011] In some embodiments of the present invention, the preparation of the CoCo-PBA nanoparticles comprises: adding potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate to deionized water, aging at room temperature, and washing, drying and grinding the obtained solid precipitate to obtain the CoCo-PBA nanoparticles.

[0012] In some embodiments of the present invention, the particle size of the CoCo-PBA nanoparticles is 0.3 μm to 1.2 μm.

[0013] In some embodiments of the present invention, the calcination temperature of the CoCo-PBA nanoparticles is 500° C., the heating rate is 5° C. / min, and the calcination time is 2 h.

[0014] In some embodiments of the present invention, based on the total mass of the raw materials forming the casting solution, the mass percentage of the Co@NC magnetic nanoparticles is 0.5wt% to 1.0wt%, the mass percentage of the polyvinylidene fluoride is 10wt%, the mass percentage of the conductive multi-walled carbon nanotubes is 1wt%, and the mass percentage of the N,N-dimethylformamide is 88wt% to 88.5wt%.

[0015] The third aspect of the present invention also provides an electrocatalytic membrane system, which includes a cathode and an anode, wherein the electrocatalytic membrane described in the first aspect or the electrocatalytic membrane prepared by the preparation method described in the second aspect serves as the cathode; and the titanium mesh serves as the anode.

[0016] The fourth aspect of the present invention further provides an application of the electrocatalytic membrane system described in the third aspect, the electrocatalytic membrane described in the first aspect, or the electrocatalytic membrane prepared by the preparation method described in the second aspect in degrading wastewater containing antibiotics.

[0017] In some embodiments of the present invention, the antibiotic in the wastewater includes levofloxacin, and the voltage applied during the electrocatalytic degradation process is 0 to 5 V and is not 0.

[0018] The present invention provides an electrocatalytic membrane (Co@NC / PVDF / CP) based on magnetically induced Co@NC nanoparticles, which achieves efficient PMS activation and simultaneous removal of pollutants. The magnetic field induces the catalytic particles to be enriched on the membrane surface, forming high-density active sites; the electric field further accelerates the activation of Co@NC nanoparticles. 2+ / Co 3+ cycle, effectively improving catalytic efficiency.

[0019] The present invention constructs an electrocatalytic membrane system through an electrocatalytic membrane, improves the reaction kinetics of the electrocatalytic membrane, and efficiently degrades antibiotics in water.

[0020] The electrocatalytic membrane of the present invention has good electrical conductivity and stability; it also has a high degradation rate and anti-pollution performance, and can be recycled.

[0021] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 This is a flow chart of the preparation process of the electrocatalytic membrane in an embodiment of the present invention.

[0024] Figure 2 This is an electron microscope image of the Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 of the present invention.

[0025] Figure 3 This is an electron microscope image of the W-Co@NC / PVDF / CP electrocatalytic membrane prepared in Comparative Example 2 of the present invention.

[0026] Figure 4 This is a SEM image of the CoCo-PBA nanoparticles prepared in Example 1 of the present invention.

[0027] Figure 5 This is the SEM image of the Co@NC magnetic nanoparticles prepared in Example 1 of the present invention.

[0028] Figure 6 This is a diagram of the degradation efficiency of levofloxacin in three electrocatalytic membrane systems in Experiment 1 of the present invention.

[0029] Figure 7 This is a diagram of the degradation efficiency of levofloxacin at different voltages in Experiment 2 of the present invention.

[0030] Figure 8 This is the 4-cycle degradation efficiency diagram of the Co@NC / PVDF / CP electrocatalytic membrane in Experiment 3 of the present invention.

[0031] Figure 9 Schematic diagram of pure water flux of Co@NC / PVDF / CP electrocatalytic membrane in Experiment 4 of the present invention. DETAILED DESCRIPTION

[0032] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0033] It should be understood that the terms used herein are for the purpose of describing specific example embodiments only and are not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms "one", "an" and "said" as used herein may also be meant to include plural forms. The terms "comprise", "include", "contain" and "have" are inclusive and therefore specify the presence of stated features, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, steps, operations, elements, parts, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be performed in the specific order described or illustrated, unless the order of execution is clearly indicated. It should also be understood that additional or alternative steps may be used.

[0034] In the description of the embodiments of the present invention, technical terms such as "first" and "second" are used solely to distinguish between different objects and should not be understood to indicate or imply relative importance or to implicitly specify the quantity, specific order, or primary and secondary relationship of the technical features indicated. In the description of the embodiments of the present invention, "plurality" means more than two, unless otherwise specifically defined.

[0035] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present invention. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute a separate or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0036] In the description of the embodiments of the present invention, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exists simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0037] In the description of the embodiments of the present invention, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0038] In the description of the embodiments of the present invention, unless otherwise expressly specified or limited, technical terms such as "installed," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0039] A first aspect of the present invention provides an electrocatalytic membrane, which includes a carbon fiber base membrane and a polyvinylidene fluoride membrane composited on the carbon fiber base membrane, and the surface of the polyvinylidene fluoride membrane is enriched and distributed with Co@NC nanoparticles based on magnetic field induction.

[0040] In the embodiment of the present invention, the structure of the electrocatalytic membrane can be expressed as Co@NC / PVDF / CP, which is specifically composed of a carbon fiber base membrane and a polyvinylidene fluoride membrane composited on the carbon fiber base membrane, and Co@NC nanoparticles distributed on the surface of the polyvinylidene fluoride membrane. In the present invention, the electrocatalytic membrane (Co@NC / PVDF / CP) is constructed based on magnetically induced Co@NC nanoparticles, achieving efficient PMS activation and simultaneous removal of pollutants. The magnetic field induction promotes the directional enrichment of catalytic particles on the membrane surface, forming a high-density active site; the electric field further accelerates the Co@NC nanoparticles. 2+ / Co 3+ cycle, effectively improving catalytic efficiency.

[0041] In an embodiment of the present invention, the particle size of the Co@NC nanoparticles is 0.3 μm to 1.2 μm. For example, the particle size of the Co@NC nanoparticles can be one of 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, or any value within the above range.

[0042] In an embodiment of the present invention, the carbon fiber base film includes but is not limited to carbon paper.

[0043] In an embodiment of the present invention, the porosity of the electrocatalytic membrane is between 27% and 42%. For example, the porosity of the electrocatalytic membrane can be one of 27.15%, 30.02%, 41.49%, or any value within the above range.

[0044] The second aspect of the present invention provides a method for preparing the electrocatalytic membrane described in the first aspect. The key to this preparation method is to use potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate to prepare CoCo-PBA nanoparticles, then calcined under an inert atmosphere to prepare Co@NC magnetic nanoparticles, and then non-solvent-induced phase separation is used to prepare the electrocatalytic membrane.

[0045] See also Figure 1 As shown, the preparation of the electrocatalytic membrane in the present invention is specifically carried out according to the following steps.

[0046] Preparation of CoCo-PBA nanoparticles

[0047] In an embodiment of the present invention, CoCo-PBA nanoparticles are prepared using potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate as raw materials.

[0048] In some embodiments of the present invention, in the preparation of CoCo-PBA nanoparticles, the molar ratio of potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate is 4:3:5.

[0049] In some embodiments of the present invention, the preparation of CoCo-PBA nanoparticles includes: adding potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate to deionized water, aging at room temperature, and washing, drying and grinding the obtained solid precipitate to obtain CoCo-PBA nanoparticles.

[0050] In some embodiments of the present invention, the particle size of the CoCo-PBA nanoparticles is 0.3 μm to 1.2 μm. For example, the particle size of the CoCo-PBA nanoparticles can be one of 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1.0 μm, 1.1 μm, 1.2 μm, or any value within the above range.

[0051] In some embodiments of the present invention, the aging time at room temperature can be set according to actual conditions, for example, the aging time can be 20 hours to 24 hours.

[0052] In some embodiments of the present invention, 40 mmol / L potassium cobalt hydride, 30 mmol / L cobalt chloride hexahydrate, and 50 mmol / L sodium citrate were added to 100 mL of deionized water and aged at room temperature for 24 hours. The solid precipitate was then washed, dried, and ground into a powder to obtain CoCo-PBA nanoparticles.

[0053] It is worth mentioning that the room temperature in the present invention generally refers to a state where no active heating or cooling is performed. In the embodiments of the present invention, the room temperature is 20°C to 30°C. For example, it can be 20°C, 25°C, 30°C, or any other value within the above range.

[0054] Preparation of Co@NC magnetic nanoparticles

[0055] In an embodiment of the present invention, polydopamine is coated on the surface of CoCo-PBA nanoparticles by oxidative self-polymerization, and calcined in a protective atmosphere. The calcined product is washed and dried to obtain Co@NC magnetic nanoparticles.

[0056] In some embodiments of the present invention, calcination is performed using a tube furnace in an inert atmosphere, such as a nitrogen atmosphere.

[0057] In some embodiments of the present invention, the calcination process is to increase the temperature to 500° C. at a rate of 5° C. / min and calcine at this temperature for 2 hours.

[0058] In some embodiments of the present invention, 100 mg of CoCo-PBA nanoparticles were dispersed in 20 mL of a 0.1 mol / L Tris (tris(hydroxymethyl)aminomethane)) aqueous solution, the pH was adjusted to 8.5 with hydrochloric acid, and then 40 mg of dopamine was added and stirred for 18 to 24 hours. Polydopamine was then coated on the surface of the CoCo-PBA nanoparticles via oxidative autopolymerization. The resulting polydopamine-coated CoCo-PBA nanoparticles were then calcined.

[0059] Preparation of Co@NC / PVDF / CP electrocatalytic membrane

[0060] In an embodiment of the present invention, a carbon fiber material is used as the base membrane, ie, a carbon fiber base membrane.

[0061] In some embodiments of the present invention, carbon fiber (CP) materials include, but are not limited to, carbon paper.

[0062] In some embodiments of the present invention, a carbon material, such as carbon paper, is ultrasonically cleaned with acetone and ethanol in sequence for 30 minutes to remove impurities, and then dried.

[0063] The drying process may be carried out by conventional drying methods in the prior art.

[0064] In an embodiment of the present invention, a non-solvent induced phase separation method is used to prepare the Co@NC / PVDF / CP electrocatalytic membrane.

[0065] 1) Preparation of casting solution

[0066] In an embodiment of the present invention, a casting solution is prepared using Co@NC magnetic nanoparticles, N,N-dimethylformamide, polyvinylidene fluoride, and conductive multi-walled carbon nanotubes.

[0067] In an embodiment of the present invention, based on the total mass of the raw materials forming the casting solution, the mass percentage of Co@NC nanoparticles is 0.5 wt% to 1.0 wt%, the mass percentage of polyvinylidene fluoride (PVDF) is 10 wt%, the mass percentage of conductive multi-walled carbon nanotubes is 1 wt%, and the mass percentage of N,N-dimethylformamide (DMF) is 88 wt% to 88.5 wt%.

[0068] The mass percentage of the Co@NC nanoparticles provided by the present invention can be one of 0.5wt%, 0.55wt%, 0.6wt%, 0.65wt%, 0.7wt%, 0.75wt%, 0.8wt%, 0.85wt%, 0.9wt%, 0.95wt%, 1.0wt% or any value that meets the above range.

[0069] The mass percentage of N,N-dimethylformamide provided by the present invention can be one of 88wt%, 88.1wt%, 88.2wt%, 88.25wt%, 88.3wt%, 88.4wt%, 88.5wt% or any value that meets the above range.

[0070] In some embodiments of the present invention, Co@NC magnetic nanoparticles are added to N,N-dimethylformamide (DMF) and ultrasonicated, and then PVDF and conductive multi-walled carbon nanotubes are added to the obtained dispersion, stirred at room temperature, and allowed to stand for degassing to obtain a casting solution.

[0071] 2) The casting liquid is evenly coated on one side surface of the carbon fiber material to form a casting liquid.

[0072] In some embodiments of the present invention, the casting solution is coated on one surface of the carbon paper using a film applicator.

[0073] 3) Magnetic induced adsorption

[0074] In an embodiment of the present invention, Co@NC magnetic nanoparticles are directed and moved and distributed on the surface of the casting liquid by magnetic attraction, and then the whole is placed in deionized water to prepare an electrocatalytic membrane.

[0075] In some embodiments of the present invention, a magnet is used to perform the magnetic attraction operation.

[0076] In some embodiments of the present invention, a magnet is fixed 1 cm above the casting liquid to attract Co@NC magnetic nanoparticles. After being exposed to the magnetic field for 60 seconds, the Co@NC magnetic nanoparticles are distributed on the surface of the casting liquid. Then, the whole is immediately placed in deionized water and soaked for 24 hours to leach out the residual solvent. Then, the prepared Co@NC / PVDF / CP electrocatalytic membrane is placed in deionized water and stored until use.

[0077] A third aspect of the present invention provides an electrocatalytic membrane system. The key to this electrocatalytic membrane system is the use of an electrocatalytic membrane as the system cathode. The construction of an integrated electrochemical filtration system for electrocatalytic peroxymonosulfate (PMS) activation for flow-through reactions provides a new approach for the efficient treatment of antibiotic wastewater. The electrocatalytic membrane not only significantly increases the generation rate of active species but also effectively mitigates membrane fouling, enhancing the system's operational stability and treatment efficiency.

[0078] In an embodiment of the present invention, the electrocatalytic membrane system uses a titanium mesh as the anode and an electrocatalytic membrane described in the first aspect of the present invention or an electrocatalytic membrane prepared by the preparation method described in the second aspect of the present invention as the cathode. This electrocatalytic membrane system may also be referred to as a Co@NC / PVDF / CP / E / PMS system.

[0079] The fourth aspect of the present invention provides an application of the electrocatalytic membrane system described in the third aspect, the electrocatalytic membrane described in the first aspect, or the electrocatalytic membrane prepared by the preparation method described in the second aspect in degrading wastewater containing antibiotics.

[0080] In an embodiment of the present invention, the antibiotic in the wastewater includes levofloxacin, for example, wastewater containing 10 ppm of levofloxacin can be degraded.

[0081] In some embodiments of the present invention, the voltage applied during the electrocatalytic degradation process is 0-5V and is not 0. For example, the voltage may be 1V, 2V, 3V, 4V, 5V, or any value within the above range.

[0082] In some embodiments of the present invention, the electrocatalytic degradation process was carried out in a glass electrochemical reactor. 150 mL of a 10 ppm levofloxacin solution was added to the reactor. A Co@NC / PVDF / CP electrocatalytic membrane was used as the cathode and a titanium mesh was used as the anode to form a Co@NC / PVDF / CP / E / PMS system. During the experiment, a DC regulated power supply was used to provide a voltage of 0 to 5 V. The experiment was stirred during the experiment. 0.1 mol·L -1 H2SO4 and 0.1mol·L -1 The initial pH of the reaction system was adjusted to 6.3 with NaOH, and the amount of peroxymonosulfate (PMS) added was 0.6 g·L -1 , 1 mL of sample was taken at fixed time intervals, and the absorbance at 280 nm was analyzed using a UV-visible spectrophotometer to determine the change in levofloxacin concentration.

[0083] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the raw materials, instruments and equipment used in the following examples, etc., can all be purchased on the market or can be obtained by existing methods; the amounts of the experimental reagents used, unless otherwise specified, are the amounts of reagents used in conventional experimental operations; the experimental methods, unless otherwise specified, are all conventional methods. It should be further noted that the following description is merely exemplary and does not specifically limit the present invention.

[0084] Example 1

[0085] Provide an electrocatalytic membrane Co@NC / PVDF / CP, see Figure 1 As shown, the preparation steps of the electrocatalytic membrane are as follows:

[0086] (1) 40 mmol / L potassium cobalt hydride, 30 mmol / L cobalt chloride hexahydrate, and 50 mmol / L sodium citrate were added to 100 mL of deionized water and aged at room temperature (25°C) for 24 h. The resulting solid precipitate was then washed, dried, and ground to obtain CoCo-PBA nanoparticles with a particle size of 1 μm.

[0087] (2) 100 mg of CoCo-PBA nanoparticles were dispersed in 20 mL of a 0.1 mol / L Tris (tris(hydroxymethyl)aminomethane)) aqueous solution, the pH was adjusted to 8.5 with hydrochloric acid, and then 40 mg of dopamine was added and stirred for 18 to 24 hours. Polydopamine was coated on the surface of the CoCo-PBA nanoparticles by oxidative self-polymerization. The polymerized material was heated to 500°C at a rate of 5°C / min in a nitrogen atmosphere in a tube furnace and calcined for 2 hours. After washing and drying, Co@NC magnetic nanoparticles with a particle size of 1 μm were obtained.

[0088] (3) The carbon paper was ultrasonically cleaned with acetone and ethanol for 30 min to remove impurities, and then dried conventionally.

[0089] (4) Preparation of Co@NC / PVDF / CP electrocatalytic membrane by non-solvent induced phase separation method:

[0090] First, Co@NC magnetic nanoparticles were added to N,N-dimethylformamide (DMF) and sonicated. Then, PVDF and conductive multi-walled carbon nanotubes were added to the dispersion, mechanically stirred at room temperature (25°C), and allowed to stand for degassing to obtain a casting solution. The mixture contained 0.5% by weight of Co@NC magnetic nanoparticles, 10% by weight of polyvinylidene fluoride (PVDF), 1% by weight of conductive multi-walled carbon nanotubes, and 88.5% by weight of DMF.

[0091] Next, the casting solution was evenly coated on one surface of the carbon paper using a film applicator to form a casting solution.

[0092] Next, a magnet was fixed 1 cm above the casting liquid to attract the Co@NC magnetic nanoparticles, causing the Co@NC magnetic nanoparticles to move in a directional manner and distribute on the surface of the casting liquid. After being exposed to the magnetic field for 60 seconds, the carbon paper was immediately placed in deionized water and soaked for 24 hours to extract the residual solvent. The Co@NC / PVDF / CP electrocatalytic membrane was prepared and stored in deionized water for later use.

[0093] Example 2

[0094] An electrocatalytic membrane Co@NC / PVDF / CP is provided. The preparation of the electrocatalytic membrane in Example 2 refers to the preparation method in Example 1, except that in Example 2, the mass percentage of Co@NC magnetic nanoparticles added is 0.75 wt%, the mass percentage of polyvinylidene fluoride (PVDF) is 10 wt%, the mass percentage of conductive multi-walled carbon nanotubes is 1 wt%, and the mass percentage of N,N-dimethylformamide (DMF) is 88.25 wt%.

[0095] Example 3

[0096] Provided is an electrocatalytic membrane Co@NC / PVDF / CP. The preparation of the electrocatalytic membrane in Example 3 refers to the preparation method in Example 1, except that in Example 3, the mass percentage of Co@NC magnetic nanoparticles added is 1.0 wt%, the mass percentage of polyvinylidene fluoride (PVDF) is 10 wt%, the mass percentage of conductive multi-walled carbon nanotubes is 1 wt%, and the mass percentage of N,N-dimethylformamide (DMF) is 88 wt%.

[0097] Example 4

[0098] An electrocatalytic membrane Co@NC / PVDF / CP is provided. The preparation of the electrocatalytic membrane in Example 4 refers to the preparation method in Example 1, except that in Example 4, the mass percentage of Co@NC magnetic nanoparticles added is 0.25 wt%, the mass percentage of polyvinylidene fluoride (PVDF) is 10 wt%, the mass percentage of conductive multi-walled carbon nanotubes is 1 wt%, and the mass percentage of N,N-dimethylformamide (DMF) is 88.75 wt%.

[0099] Comparative Example 1

[0100] Provided is an electrocatalytic membrane PVDF / CP, the preparation steps of the electrocatalytic membrane are as follows:

[0101] (1) The carbon paper was ultrasonically cleaned with acetone and ethanol for 30 min to remove impurities, and then dried conventionally.

[0102] (2) Preparation of PVDF / CP electrocatalytic membrane by non-solvent induced phase separation method:

[0103] First, PVDF and conductive multi-walled carbon nanotubes were added to N,N-dimethylformamide (DMF), mechanically stirred at room temperature (25°C), and allowed to stand for degassing to obtain a casting solution. The solution contained 10% by weight of PVDF, 1% by weight of conductive multi-walled carbon nanotubes, and 89% by weight of DMF.

[0104] Next, the casting liquid was evenly coated on one side of the carbon paper using a film applicator to form a casting liquid. The carbon paper was immediately immersed in deionized water for 24 hours to extract the residual solvent to obtain a PVDF / CP electrocatalytic membrane, which was then stored in deionized water for later use.

[0105] Comparative Example 2

[0106] An electrocatalytic membrane W-Co@NC / PVDF / CP is provided. In Comparative Example 2, magnetic induction to attract Co@NC magnetic nanoparticles is not used. The preparation steps of the electrocatalytic membrane are as follows:

[0107] (1) 40 mmol / L potassium cobalt hydride, 30 mmol / L cobalt chloride hexahydrate, and 50 mmol / L sodium citrate were added to 100 mL of deionized water and then aged at room temperature (25°C) for 24 h. The resulting solid precipitate was then washed, dried, and ground to obtain CoCo-PBA nanoparticles with a particle size of 1 μm. Figure 4 shown.

[0108] (2) 100 mg of CoCo-PBA nanoparticles were dispersed in 20 mL of 0.1 mol / L Tris (tris(hydroxymethyl)aminomethane)) aqueous solution, adjusted to pH 8.5 with hydrochloric acid, and then 40 mg of dopamine was added and stirred for 18 to 24 hours. Polydopamine was coated on the surface of the CoCo-PBA nanoparticles by oxidative self-polymerization. The polymerized material was heated to 500 °C at a rate of 5 °C / min in a nitrogen atmosphere in a tube furnace and calcined for 2 hours. After washing and drying, Co@NC magnetic nanoparticles with a particle size of 1 μm were obtained. Figure 5 shown.

[0109] (3) The carbon paper was ultrasonically cleaned with acetone and ethanol for 30 min to remove impurities, and then dried conventionally.

[0110] (4) Preparation of Co@NC / PVDF / CP electrocatalytic membrane by non-solvent induced phase separation method:

[0111] First, Co@NC magnetic nanoparticles were added to N,N-dimethylformamide (DMF) and sonicated. Then, PVDF and conductive multi-walled carbon nanotubes were added to the dispersion, mechanically stirred at room temperature (25°C), and allowed to stand for degassing to obtain a casting solution. The mixture contained 0.5% by weight of Co@NC magnetic nanoparticles, 10% by weight of polyvinylidene fluoride (PVDF), 1% by weight of conductive multi-walled carbon nanotubes, and 88.5% by weight of DMF.

[0112] Next, the casting liquid was evenly coated on one side of the carbon paper using a film applicator to form a casting liquid. The carbon paper was immediately placed in deionized water and soaked for 24 hours to extract the residual solvent. The W-Co@NC / PVDF / CP electrocatalytic membrane was prepared and stored in deionized water for later use.

[0113] Performance Testing

[0114] Experiment 1)

[0115] The Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 was used as the cathode and the titanium mesh was used as the anode to form an electrocatalytic membrane system 1.

[0116] The PVDF / CP electrocatalytic membrane prepared in Comparative Example 1 was used as the cathode and the titanium mesh was used as the anode to form an electrocatalytic membrane system 2.

[0117] The W-Co@NC / PVDF / CP electrocatalytic membrane prepared in Comparative Example 2 was used as the cathode and the titanium mesh was used as the anode to form the electrocatalytic membrane system 3.

[0118] The same experimental process was used for electrocatalytic membrane systems 1 to 3. Specifically, a DC regulated power supply was used to provide a voltage of 2 V. Stirring was performed during the experiment, and 0.1 mol·L -1 H2SO4 and 0.1mol·L -1 The initial pH of the reaction system was adjusted to 6.3 by NaOH, and the amount of PMS added was 0.6 g·L -1 , 1 mL of sample was taken at fixed time intervals, and the absorbance at 280 nm was analyzed by UV-visible spectrophotometer to determine the change in levofloxacin concentration, and the removal rate (R) was calculated using formula (1).

[0119]

[0120] Where c1 and c0 are the concentrations of pollutants in the filtrate and feed, respectively.

[0121] Depend on Figure 6 It can be seen that by applying a voltage of 2.0 V and adjusting the pH to 6.3, the removal rate or degradation rate of levofloxacin by the Co@NC / PVDF / CP electrocatalytic membrane in Example 1 is as high as 99.1% within 30 minutes, which is significantly better than the electrocatalytic membranes prepared in Comparative Examples 1 and 2.

[0122] Experiment 2)

[0123] The Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 was used as the cathode and the titanium mesh was used as the anode to form an electrocatalytic membrane system.

[0124] The experiment used a DC regulated power supply to provide a voltage of 0 to 5 V. Stirring was performed during the experiment, and 0.1 mol·L -1 H2SO4 and 0.1mol·L -1 The initial pH of the reaction system was adjusted to 6.3 by NaOH, and the amount of PMS added was 0.6 g·L -1 , 1 mL of sample was taken at fixed time intervals, and the absorbance at 280 nm was analyzed using a UV-visible spectrophotometer to determine the change in levofloxacin concentration.

[0125] Depend on Figure 7 It can be seen that when the voltage increases from 0V to 2V, the degradation rate of levofloxacin increases from 73.5% to 99.1%, indicating that the external electric field can effectively promote the electron transfer process and accelerate the Co 2+ / Co 3+ The redox cycle of the PMS is enhanced, thereby increasing the activation efficiency of the PMS and improving the generation of active species. However, when the voltage is further increased to 3V and 5V, the degradation rate of levofloxacin drops to 88.4% and 76.3%, respectively, showing a nonlinear trend. This phenomenon can be attributed to the fact that in the higher voltage range (>2V), the excessive electric field enhances the hydrogen evolution reaction. In the hydrogen evolution reaction, H + With HSO5 - Competing for electrons on the electrodes, the high electric field also produces electric field resistance, thereby reducing HSO5 - The interaction between the cathode and the membrane ultimately inhibits the degradation efficiency of levofloxacin. It can also be concluded that when the voltage is 2V, the degradation rate of levofloxacin by the Co@NC / PVDF / CP electrocatalytic membrane reaches the optimal level.

[0126] Experiment 3)

[0127] The Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 was subjected to four cyclic degradation experiments to verify its stability and reusability during the catalytic degradation process.

[0128] like Figure 8 As shown, after four cycles, each lasting 30 minutes, the Co@NC / PVDF / CP electrocatalytic membrane of the present invention exhibited a relatively high removal efficiency of over 80%. This remarkable result demonstrates that the electrocatalytic membrane of the present invention is recyclable and can operate efficiently at room temperature.

[0129] Experiment 4)

[0130] Pure water flux tests were conducted on the Co@NC / PVDF / CP electrocatalytic membranes prepared in Examples 1 to 4, as well as the PVDF / CP and W-Co@NC / PVDF / CP electrocatalytic membranes prepared in Comparative Examples 1 to 2. All three membranes were tested using dead-end filtration. Prior to testing, the membranes were pre-pressed at 0.1 MPa for 30 minutes, followed by filtration at 0.1 MPa.

[0131] The membrane flux (J) is calculated by formula (2):

[0132]

[0133] Where A, Δt and V are the effective membrane filtration area (m 2 ), penetration time (h) and penetration water volume (L).

[0134] like Figure 9 As shown in Figure 2, with the increase of the doping amount of Co@NC magnetic nanoparticles, the pure water flux of the membrane first increases and then decreases, and reaches a maximum of 180 L·m at 0.5 wt%. -2 ·h -1 bar -1 This is because an appropriate amount of Co@NC magnetic nanoparticles can improve the membrane's wettability, optimize the membrane's micropore structure and water channels, and help increase the permeation rate of water molecules. When the loading is further increased to 0.75wt% and 1wt%, the casting solution concentration increases, resulting in a thicker membrane layer and increased water flow resistance.

[0135] Experiment 5)

[0136] The morphologies of the Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 and the W-Co@NC / PVDF / CP electrocatalytic membrane prepared in Comparative Example 2 were detected using a scanning electron microscope (SEM).

[0137] Combine Figure 2 and Figure 3 It can be seen that for the W-Co@NC / PVDF / CP electrocatalytic membrane without magnetic induction, only a small number of particles are dispersed on the membrane surface, and the distribution is relatively random. In contrast, the Co@NC / PVDF / CP electrocatalytic membrane after magnetic induction shows a more concentrated particle distribution feature, with particles significantly concentrated on the membrane surface, forming a relatively uniform and dense distribution.

[0138] Experiment 6)

[0139] Porosity test: The porosity (ε) of the membrane was measured using the dry-wet film weight method. The specific test process is as follows.

[0140] First, cut a 2 cm × 2 cm electrocatalytic membrane sample, wipe off the pure water on its surface, and weigh its mass (to 4 decimal places), recording it as W1. Then, place the weighed membrane sample in a vacuum drying oven at 25°C and dry it to a constant weight. The mass of the dried membrane sample is weighed using the same electronic balance and recorded as W2. Finally, its porosity is calculated using Equation (3).

[0141]

[0142] Where: W1 is the mass of the membrane when it is completely wetted, g; W2 is the mass of the membrane after vacuum drying at 25°C, g; ρ is the density of pure water (0.998 g·cm -1 ); A is the membrane sample area, m 2 ; l is the thickness of the film sample, m.

[0143] The porosity of the electrocatalytic membranes prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was tested. The results are shown in Table 1.

[0144] Table 1 Summary of the porosity of the electrocatalytic membranes prepared in the examples and comparative examples

[0145] Membrane performance Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Porosity (%) 41.49 30.02 27.15 23.03 18.61 38.99

[0146] As shown in Table 1, the porosity of the Co@NC / PVDF / CP electrocatalytic membrane prepared in Example 1 is 41.49%, significantly higher than the 38.99% of the W-Co@NC / PVDF / CP electrocatalytic membrane in Comparative Example 2. Higher porosity means that the membrane has more void volume for water molecules to pass through, effectively reducing mass transfer resistance and promoting rapid water penetration. Therefore, increased porosity plays a significant role in improving the membrane's water permeability.

[0147] The electrocatalytic membranes of the present invention offer excellent conductivity and stability, high degradation rates, and anti-pollution properties, and are recyclable. Using the electrocatalytic membranes of the present invention to degrade antibiotic wastewater not only significantly increases the generation rate of active species, but also effectively mitigates membrane fouling, enhancing system operational stability and treatment efficiency.

[0148] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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. An electrocatalytic membrane, characterized in that The invention comprises a carbon fiber base film and a polyvinylidene fluoride film composited on the carbon fiber base film, wherein Co@NC magnetic nanoparticles are oriented and enriched on the surface of the polyvinylidene fluoride film based on magnetic field induction.

2. The electrocatalytic membrane according to claim 1, wherein The particle size of the Co@NC magnetic nanoparticles is 0.3 μm to 1.2 μm; Preferably, the carbon fiber base film comprises carbon paper.

3. A method for preparing an electrocatalytic membrane according to claim 1 or 2, characterized in that: The preparation method comprises the following steps: CoCo-PBA nanoparticles were prepared using potassium cobalt hydride, cobalt chloride hexahydrate, and sodium citrate as raw materials; Polydopamine is coated on the surface of the CoCo-PBA nanoparticles by oxidative self-polymerization, and the particles are calcined in a protective atmosphere. The calcined products are washed and dried to obtain Co@NC magnetic nanoparticles. A casting solution is prepared using the Co@NC magnetic nanoparticles, N,N-dimethylformamide, polyvinylidene fluoride and conductive multi-walled carbon nanotubes. The casting solution is evenly coated on one side of the carbon fiber material to form a casting solution. The Co@NC magnetic nanoparticles are induced to distribute on the surface by magnetic attraction, and then the entire solution is placed in deionized water to obtain the electrocatalytic membrane.

4. The method for preparing an electrocatalytic membrane according to claim 3, wherein: In the preparation of the CoCo-PBA nanoparticles, the molar ratio of the potassium cobalt hydride, the cobalt chloride hexahydrate and the sodium citrate is 4:3:

5.

5. The method for preparing an electrocatalytic membrane according to claim 3, wherein: The preparation of the CoCo-PBA nanoparticles comprises: Potassium cobalt hydride, cobalt chloride hexahydrate and sodium citrate are added to deionized water, aged at room temperature, and the obtained solid precipitate is washed, dried and ground to obtain the CoCo-PBA nanoparticles; Preferably, the particle size of the CoCo-PBA nanoparticles is 0.3 μm to 1.2 μm.

6. The method for preparing an electrocatalytic membrane according to claim 3, wherein: The calcination temperature of the CoCo-PBA nanoparticles is 500° C., the heating rate is 5° C. / min, and the calcination time is 2 h.

7. The method for preparing an electrocatalytic membrane according to claim 3, wherein: Based on the total mass of the raw materials forming the casting solution, the mass percentage of the Co@NC magnetic nanoparticles is 0.5wt% to 1.0wt%, the mass percentage of the polyvinylidene fluoride is 10wt%, the mass percentage of the conductive multi-walled carbon nanotubes is 1wt%, and the mass percentage of the N,N-dimethylformamide is 88wt% to 88.5wt%.

8. An electrocatalytic membrane system, characterized in that: The electrocatalytic membrane system comprises a cathode and an anode, wherein: The cathode is an electrocatalytic membrane according to any one of claims 1 to 2 or an electrocatalytic membrane prepared by the preparation method according to any one of claims 3 to 7; A titanium mesh was used as the anode.

9. Use of the electrocatalytic membrane system according to claim 8 or the electrocatalytic membrane according to any one of claims 1 to 2 in degrading wastewater containing antibiotics.

10. The use according to claim 9, characterized in that The antibiotics in the wastewater include levofloxacin, and the voltage applied during the electrocatalytic degradation process is 0-5V and not 0.

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