Multiple confined catalytic ceramic nanofiber membrane, preparation method and application thereof

Abstract

The application discloses a kind of multiple confined catalytic ceramic nanofiber membranes and preparation method and application thereof, the multiple confined catalytic ceramic nanofiber membrane is asymmetric flat ceramic membrane, including porous ceramic membrane support, halloysite nanotube layer and catalyst with Fenton-like catalytic activity, the halloysite nanotube layer is attached to the surface of the porous ceramic membrane support, the catalyst is loaded on the surface and the pore of the porous ceramic membrane support, the catalyst is also loaded on the surface and the pore of halloysite nanotube in the halloysite nanotube layer.The multiple confined catalytic ceramic nanofiber membrane of the application is extremely strong in hydrophilicity, membrane flux is high, Fenton-like catalytic activity is high, can efficiently oxidize and remove new pollutants in water, and catalyst stability is strong, can be widely applied in medical wastewater and various water treatments.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane technology, and in particular to a multi-confined catalytic ceramic nanofiber membrane, its preparation method, and its application. Background Technology

[0002] In recent years, with rapid economic development, water pollution, especially the pollution of new water pollutants, has become increasingly serious. The research and practical application of efficient technologies for removing new pollutants in water treatment processes have become one of the most urgent tasks in contemporary water treatment. Fenton-like reactions based on transition metal oxides can efficiently oxidize and degrade new pollutants through the reactive oxygen species generated in the Fenton-like system, and are considered a promising new pollutant treatment technology in the new era of water treatment. However, traditional Fenton-like reactions still face many technical bottlenecks that urgently need to be overcome, such as the limited catalytic activity of traditional transition metal oxides, low utilization rate of reactive oxygen species, agglomeration of powdered catalyst particles, and difficulties in catalyst recovery and regeneration.

[0003] Ceramic membranes, such as inorganic ceramic membranes with alumina as the main component, possess strong oxidation resistance and can serve as excellent supports for transition metal oxide catalysts. Loading catalysts onto nano-ceramic membrane supports not only easily solves the problems of powder catalyst agglomeration and recovery difficulties, but also allows the pores of nano-ceramic membranes to enhance the mass transfer efficiency of reactive oxygen species to organic pollutants in Fenton-like reactions in nanoreactors, significantly improving the utilization rate of reactive oxygen species and the removal rate of new pollutants. However, current catalytic ceramic membranes are still mainly particle-packed ceramic membranes supported on traditional monometallic transition metal oxide catalysts such as iron oxides and manganese oxides. These membranes still suffer from drawbacks such as low catalytic efficiency, poor catalytic stability, low membrane porosity, high transmembrane pressure, severe membrane fouling during long-term operation, and high operating and maintenance costs, which urgently need to be overcome.

[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a multi-confined catalytic ceramic nanofiber membrane, its preparation method, and its application.

[0006] The present invention adopts the following technical solution:

[0007] In a first aspect, a multi-confined catalytic ceramic nanofiber membrane is provided. The multi-confined catalytic ceramic nanofiber membrane is an asymmetric planar ceramic membrane, comprising a porous ceramic membrane support, an halloysite nanotube layer, and a catalyst with Fenton-like catalytic activity. The halloysite nanotube layer is attached to the surface of the porous ceramic membrane support, and the catalyst is loaded on the surface of the porous ceramic membrane support and within its pores. The catalyst is also loaded on the surface of the halloysite nanotubes in the halloysite nanotube layer and within its pores.

[0008] Secondly, a method for preparing a multi-confined catalytic ceramic nanofiber membrane is provided, comprising the following steps:

[0009] (1) Clean the porous ceramic membrane support for later use;

[0010] (2) The halloysite nanotube powder, dispersant and stabilizer are mixed evenly in ultrapure water to prepare the film slurry;

[0011] (3) The porous ceramic membrane support obtained in step (1) is immersed in the membrane slurry obtained in step (2) for slurry coating, and then sintered at high temperature to form a membrane.

[0012] (4) The membrane obtained in step (3) is immersed in the precursor solution of the catalyst, so that the precursor solution is fully adsorbed onto the membrane surface and fills the membrane pores to load the catalyst, and then sintered at high temperature to obtain the multi-confined catalytic ceramic nanofiber membrane.

[0013] Thirdly, an application of a multi-confined catalytic ceramic nanofiber membrane in water treatment is provided. The multi-confined catalytic ceramic nanofiber membrane achieves efficient removal of pollutants, especially new pollutants, in water treatment through a coupled Fenton-like reaction.

[0014] The present invention has the following beneficial effects:

[0015] In this invention, halloysite, as a natural hollow tubular nanomaterial, possesses advantages such as abundant natural content, low cost, high biocompatibility, strong thermal stability, high specific surface area, and extremely high hydrophilicity. This invention utilizes halloysite nanotubes to construct novel ceramic fiber membranes. The novel ceramic nanofiber membranes constructed based on halloysite nanotubes not only have low preparation costs but also exhibit higher porosity and membrane flux compared to particle-packed ceramic membranes, making them excellent catalyst supports. Multi-walled halloysite possesses a central nanoscale confinement space and interlayer angstrom-level confinement spaces, providing multiple confined reaction spaces for catalytic reactions. This improves molecular mass transfer efficiency and new pollutant removal rates in Fenton-like catalytic reactions. The nanoscale confinement space of halloysite nanotubes also allows for more stable catalyst loading, enhancing the catalytic stability of the membrane. The multi-confined catalytic ceramic nanofiber membrane of this invention exhibits extremely high hydrophilicity and membrane flux, making it widely applicable in various water treatment processes, including medical wastewater treatment. Specifically, this invention has the following advantages:

[0016] (1) Multi-confined catalysis: The multi-confined catalytic ceramic nanofiber membrane of this invention is mainly constructed of multi-walled halloysite nanotubes, which not only increases the porosity and water permeability of the ceramic membrane, but also provides a multi-confined catalytic reaction space for Fenton-like reactions through the nano-confined space inside the halloysite nanotube channels and the angstrom-level confinement space between the multi-walled layers. The multi-confined space helps to improve the mass transfer efficiency and utilization rate of reactive oxygen species in Fenton-like reactions, thereby improving the oxidation and removal efficiency of new pollutants and effectively overcoming the disadvantage of low utilization rate of reactive oxygen species in open Fenton-like systems due to their extremely short lifespan and mass transfer distance.

[0017] (2) Strong catalytic stability: In the multi-confined catalytic ceramic nanofiber membrane layer of the present invention, the catalyst confined and loaded in halloysite nanotubes has stronger catalytic stability and has the advantages of being difficult to dissolve and difficult to fall off.

[0018] (3) High catalytic activity: In a preferred embodiment, the multi-confined catalytic ceramic nanofiber membrane is loaded with highly catalytically active multi-component transition metal oxides, which can efficiently catalyze various oxidants widely used in water treatment, such as ozone, hydrogen peroxide, and persulfate. This membrane possesses high catalytic activity for various, but not limited to, Fenton-like advanced oxidation processes, such as hydrogen peroxide, ozone, persulfate, ozone / hydrogen peroxide, and hydrogen peroxide / persulfate, thereby achieving the dual purpose of enhanced removal of new pollutants and membrane fouling control in actual water treatment through coupling with Fenton-like advanced oxidation reactions. Attached Figure Description

[0019] Figure 1 This is a micro-electron microscope image of the multi-confined catalytic ceramic nanofiber membrane in Example 1 of the present invention.

[0020] Figure 2 yes Figure 1 Electron micrograph at magnification of the area in the middle circle.

[0021] Figure 3 This is the result of the removal of ofloxacin from water by hydrogen peroxide catalyzed by the multi-confined catalytic ceramic nanofiber membrane in Example 2 of the present invention.

[0022] Figure 4 This is the result of the removal of acetaminophen from water by hydrogen peroxide catalyzed by the multi-confined catalytic ceramic nanofiber membrane in Example 3 of the present invention. Detailed Implementation

[0023] The embodiments of the present invention will be described in detail below. It should be emphasized that the following description is merely exemplary and not intended to limit the scope or application of the invention. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. In this document, "room temperature" refers to 20-25°C.

[0024] This invention provides a multi-confined catalytic ceramic nanofiber membrane, which is an asymmetric planar ceramic membrane comprising a porous ceramic membrane support, an halloysite nanotube layer, and a catalyst with Fenton-like catalytic activity. The halloysite nanotube layer is attached to the surface of the porous ceramic membrane support, and the catalyst is loaded on the surface and within the pores of the porous ceramic membrane support. The catalyst is also loaded on the surface and within the pores of the halloysite nanotubes in the halloysite nanotube layer.

[0025] The multi-confined catalytic ceramic nanofiber membrane is mainly constructed from halloysite nanotubes. Halloysite nanotubes are hollow tubular structures with open cavities formed by the rolling of lamellar sheets. The tube walls are composed of several layers of stacked structural units. The surface of halloysite nanotubes is rich in hydroxyl groups and has strong hydrophilicity, which is beneficial to improving membrane flux. The halloysite nanotube layer formed by halloysite nanotubes has both angstrom-scale (the spacing between the lamellar sheets of the halloysite nanotube wall is on the angstrom scale) and nanoscale (the pore size of the central cavity of the halloysite nanotube is on the nanoscale) confinement space, which is beneficial to enhancing the catalytic reaction.

[0026] In some embodiments, the thickness of the halloysite nanotube layer is 10-50 μm; the pore size of the central pore of the halloysite nanotube is 10-30 nm, the outer diameter of the halloysite nanotube is 30-190 nm, and the length of the halloysite nanotube is 0.02-30 μm; the spacing between the layers of the halloysite nanotube wall is...

[0027] In some embodiments, the catalyst is a multi-element transition metal oxide; the multi-element transition metal oxide is at least one selected from CuMnO, FeMnO, TiMnO, ZnMnO, CuFeMnO, CuZnMnO, CuTiMnO, and TiMnFeO.

[0028] In some embodiments, the catalyst loading in the multi-confined catalytic ceramic nanofiber membrane is 0.5 wt% to 10 wt%.

[0029] In some embodiments, the particle size of the catalyst is 5-20 nm.

[0030] In some embodiments, the porous ceramic membrane support material is aluminum oxide, or a mixture of aluminum oxide and silicon dioxide (wherein the mass content of silicon dioxide is ≤40%). The porous ceramic membrane support is formed by stacking and sintering the above materials.

[0031] In some embodiments, the pore size of the porous ceramic membrane support is 1-3 μm.

[0032] In some embodiments, the thickness of the porous ceramic membrane support is 1-2 mm.

[0033] In some embodiments, the halloysite nanotube layer is sintered from halloysite nanotubes. The resulting multi-confined catalytic ceramic nanofiber membrane not only contains angstrom-scale and nanometer-scale multi-confined spaces, but also possesses high Fenton-like catalytic activity. It can significantly improve the yield and utilization rate of reactive oxygen species in Fenton-like reactions, and achieve highly selective oxidation removal of new pollutants in water treatment. This membrane is extremely hydrophilic and has high membrane flux, and can be widely used in various water treatments such as medical wastewater.

[0034] The present invention also provides a method for preparing a multi-confined catalytic ceramic nanofiber membrane, which includes the following steps:

[0035] (1) Clean the porous ceramic membrane support for later use; preferably, the commercial porous ceramic membrane support can be cut to the required size and ultrasonically cleaned in ultrapure water for 20-60 min, and dried at 80-100℃ for 5-10 h for later use.

[0036] (2) The halloysite nanotube powder, dispersant and stabilizer are mixed evenly in ultrapure water to prepare a film slurry; preferably, the halloysite nanotube powder, dispersant and stabilizer are mixed evenly in ultrapure water and then ultrasonicated for 30-60 minutes to prepare a film slurry.

[0037] (3) The porous ceramic membrane support obtained in step (1) is immersed in the membrane slurry obtained in step (2) for slurry coating, and then sintered at high temperature to form a membrane. The membrane includes a porous ceramic membrane support and an halloysite nanotube layer attached to the porous ceramic membrane support.

[0038] (4) Immerse the membrane obtained in step (3) into the precursor solution of the catalyst, so that the precursor solution is fully adsorbed onto the membrane surface and fills the membrane pores (i.e., the precursor solution is fully adsorbed onto the surfaces and pores of the porous ceramic membrane support and halloysite nanotube layer) to load the catalyst, and then sinter at high temperature to obtain the multi-confined catalytic ceramic nanofiber membrane.

[0039] In the above embodiments, a new generation of multi-confined catalytic ceramic nanofiber membrane with both high flux and high catalytic activity was prepared on a porous ceramic membrane support by using halloysite nanotubes as the main membrane material and employing a process of slurry coating-high temperature sintering-impregnation modification-high temperature sintering.

[0040] In some embodiments, the content of halloysite nanotube powder in the film slurry of step (2) is 1wt%-6wt%, the content of dispersant is 1wt%-2wt%, the content of stabilizer is 2wt%-3wt%, and the balance is water.

[0041] In some embodiments, the dispersant is at least one selected from sodium hexametaphosphate, sodium pyrophosphate, trisodium phosphate, tetrasodium phosphate, sodium hexametaphosphate, sodium metasilicate, and sodium disilicate.

[0042] In some embodiments, the stabilizer is at least one of methylcellulose and carboxymethylcellulose.

[0043] In some embodiments, the halloysite nanotube powder is natural halloysite nanotubes.

[0044] In some embodiments, the high-temperature sintering process in steps (3) and (4) is independently performed as follows: heating to 500-800℃ at a heating rate of 2-5℃ / min and calcining for 2-4 hours.

[0045] In some embodiments, the slurry coating process in step (3) is as follows: the porous ceramic membrane support obtained in step (1) is immersed in the membrane slurry obtained in step (2) at least once, and after each slurry immersion, it is dried at 20-25°C for 10-12 hours to form a membrane of a predetermined thickness, and then dried at 50-90°C for 10-12 hours; preferably, the number of slurry immersions is 1-10 times; preferably, the time for a single slurry immersion is 5-20 seconds.

[0046] In some embodiments, the process of supporting the catalyst in step (4) is as follows: at room temperature,The membrane obtained in step (3) is immersed in the precursor solution of the catalyst at least once. After each immersion, it is dried at 20-25°C for 10-12 hours to allow the precursor solution to be fully adsorbed onto the surface of the membrane pores and fill the membrane pores, thereby loading a predetermined amount of catalyst. The membrane is then dried at 50-90°C for 10-12 hours. Preferably, the number of immersions is 1-5. Preferably, the time for each immersion is 0.5-12 hours.

[0047] In some embodiments, the precursor solution in step (4) contains transition metal ions and an alkaline precipitant. The concentration of the transition metal ions is 0.01-1.5 mol / L, and they include binary, ternary, or multi-element metal ions such as Cu, Fe, Mn, Zn, and Ti. The concentration of the alkaline precipitant is 0.015-2.5 mol / L. The alkaline precipitant is at least one of urea and sodium hydroxide.

[0048] In some embodiments, the concentration ratio of each metal ion in the precursor solution conforms to the metal element ratio of spinel AB2O4 or perovskite ABO3 metal oxide.

[0049] The present invention also provides an application of a multi-confined catalytic ceramic nanofiber membrane in water treatment, wherein the multi-confined catalytic ceramic nanofiber membrane achieves efficient removal of pollutants, especially new pollutants, in water treatment through a coupled Fenton-like reaction.

[0050] In the above applications, the multi-confined catalytic ceramic nanofiber membrane, when used in conjunction with oxidants such as hydrogen peroxide, ozone, and persulfate, constructs an integrated system of Fenton-like advanced oxidation and ceramic membrane filtration. This system efficiently oxidizes and degrades conventional organic pollutants and new pollutants while separating them through membrane filtration, achieving highly efficient purification of various water and wastewater, including drinking water, municipal sewage, and medical wastewater. Specifically, the multi-confined catalytic ceramic nanofiber membrane contains a highly catalytically active multi-component Fenton-like metal oxide catalyst loaded on halloysite nanotubes. This catalyst can more efficiently decompose oxidants such as hydrogen peroxide, ozone, and persulfate to generate reactive oxygen species such as hydroxyl radicals, singlet oxygen, or superoxide radicals, thereby initiating a continuous Fenton-like reaction. The angstrom- and nanometer-scale multi-confined spaces contained in this multi-confined catalytic ceramic nanofiber membrane can shorten the mass transfer distance between reactive oxygen species and target pollutants during the Fenton-like reaction, improving molecular mass transfer efficiency and thus enhancing the removal of pollutants (especially new pollutants) from water.

[0051] In some implementations, the application includes the following steps:

[0052] S1. The multi-confined catalytic ceramic nanofiber membrane is installed in the membrane tank, and the water to be treated is continuously filtered using a constant flux dead-end filtration method; preferably, the membrane flux is 20-120 L / (m²).2 ·h);

[0053] S2. During membrane filtration, an oxidant is added to the membrane tank to initiate a Fenton-like reaction catalyzed by the multi-confined catalytic ceramic nanofiber membrane, thereby enhancing the removal of new pollutants (especially new pollutants) in the water; preferably, the oxidant is at least one of hydrogen peroxide and persulfate; preferably, the dosage of the oxidant is 0.01-20 mM.

[0054] In some embodiments, step S3 is also included: during the membrane filtration process, in-situ ozone aeration is performed at the bottom of the multi-confined catalytic ceramic nanofiber membrane, with an air-to-water ratio of 3:1-8:1 and an in-situ ozone dosage of 0.5-20 mg / L, in order to further enhance the removal of pollutants (especially new pollutants) in the water.

[0055] The new pollutants include, but are not limited to, the following types of new pollutants commonly found in natural water bodies: ofloxacin, ciprofloxacin, tiamulin, acetaminophen, salicylic acid, ibuprofen, erythromycin, tetracycline, oxytetracycline, roxithromycin, clarithromycin, azithromycin, etc.

[0056] In a specific embodiment of the present invention, the removal rate of new pollutants in water can exceed 99%.

[0057] The following describes specific embodiments of the present invention.

[0058] Example 1

[0059] A method for preparing a multi-confined catalytic ceramic nanofiber membrane includes the following steps:

[0060] (1) Preparation of porous ceramic membrane support: Cut the commercial alumina porous ceramic membrane support to a fixed size, and ultrasonically clean it in ultrapure water for 30 min, dry it at 80℃ for 6 h, and set it aside.

[0061] (2) Preparation of membrane slurry: Mix 4 wt% halloysite nanotube powder, 1 wt% sodium hexametaphosphate dispersant and 2 wt% carboxymethyl cellulose dispersant in 93 wt% ultrapure water until homogeneous, and then sonicate for 30 min to prepare membrane slurry for later use.

[0062] (3) One-time slurry coating: The porous ceramic membrane support prepared in step (1) is immersed in the membrane slurry prepared in step (2) for slurry coating for 15s, dried at 25℃ for 12h, and then dried at 80℃ for 12h.

[0063] (4) High-temperature sintering to form a membrane: The membrane dried in step (3) is heated to 600°C for 2 hours in a high-temperature furnace at a heating rate of 5°C / min, and finally a novel ceramic nanofiber membrane with multiple confined pore size distribution is obtained.

[0064] (5) Catalyst loading and sintering into a membrane: The novel ceramic nanofiber membrane with multiple confined pore size distribution obtained in step (4) is immersed in the catalyst precursor solution at room temperature, so that the precursor solution is fully adsorbed onto the surface of the ceramic membrane pores and fills the membrane pores. The precursor solution includes 0.6 mol / L of Cu, Fe, and Mn ternary transition metal ions (the concentration ratio of each ion is Cu:Mn:Fe = 2:3:10) and 1.0 mol / L of urea.

[0065] (6) After the fully impregnated membrane is dried at 25°C for 12 hours, it is dried at 80°C for 12 hours. The dried membrane is then calcined in a high-temperature furnace at a heating rate of 5°C / min to 600°C for 2 hours to finally produce a multi-confined catalytic ceramic nanofiber membrane.

[0066] like Figure 1 As shown, the multi-confined catalytic ceramic nanofiber membrane prepared according to steps (1)-(6) in Example 1 includes a porous ceramic membrane support 1 loaded with a catalyst and a halloysite nanotube layer 2 loaded with a catalyst attached to the surface of the porous ceramic membrane support 1 loaded with a catalyst. The average thickness of the halloysite nanotube layer 2 loaded with a catalyst is 10 μm. Figure 2 As shown, the central pore diameter of the halloysite nanotubes is 10-30 nm, the outer diameter is 30-190 nm, the length is 0.02-30 μm, and the spacing between the layers of the halloysite nanotube wall is... The supported catalyst has a particle size between 5-20 nm. As shown in Table 1 below, this multi-confined catalytic ceramic nanofiber membrane is mainly composed of six elements: O, Al, Si, Mn, Fe, and Cu. At a membrane flux of 40 L / (m²), 2 Under the conditions of (·h), the pure water permeation of this multi-confined catalytic ceramic nanofiber membrane is approximately 181 L / (m³). 2 The pure water permeation of this multi-confined catalytic ceramic nanofiber membrane (·h·bar) is significantly higher than that of traditional particle-stacking ceramic membranes.

[0067] Table 1

[0068]

[0069]

[0070] Example 2

[0071] Water treatment was performed using the multi-confined catalytic ceramic nanofiber membrane provided in Example 1. This membrane can enhance the removal of new pollutants from water through a coupled Fenton-like reaction. Specifically, as... Figure 3As shown, a constant flux dead-end filtration method is used, with a flow rate of 40 L / (m³). 2 A continuous membrane filtration experiment was conducted at a membrane flux of 1 mg / L to treat water containing 1 mg / L ofloxacin. With a hydrogen peroxide dosage of 5 mM, over 99% of ofloxacin was removed from the effluent. This result confirms that the catalytic membrane prepared in this invention possesses strong Fenton-like catalytic activity and can efficiently enhance the removal of new pollutants in water. After 24 hours of continuous membrane filtration, the ofloxacin removal rate in the effluent still exceeded 99%, demonstrating the strong catalytic stability of this multi-confined catalytic ceramic nanofiber membrane.

[0072] Example 3

[0073] Water treatment was performed using the multi-confined catalytic ceramic nanofiber membrane provided in Example 1. This membrane can enhance the removal of new pollutants from water through a coupled Fenton-like reaction. Specifically, as... Figure 4 As shown, a constant flux dead-end filtration method is used, with a flow rate of 40 L / (m³). 2 Continuous membrane filtration experiments were conducted at a membrane flux of ·h) to treat water containing 1.5 mg / L paracetamol. With a hydrogen peroxide dosage of 5 mM, over 99.9% of paracetamol was removed from the effluent. This result confirms that the catalytic membrane prepared in this invention possesses strong Fenton-like catalytic activity and can efficiently enhance the removal of new pollutants such as paracetamol from water. Even after 48 hours of continuous membrane filtration, the removal rate of paracetamol in the effluent remained above 99.9%, demonstrating the strong catalytic stability of this multi-confined catalytic ceramic nanofiber membrane during long-term operation.

[0074] This invention overcomes the problems of low catalytic efficiency, poor catalytic stability, low membrane porosity, high transmembrane pressure, severe membrane fouling during long-term operation, and high operation and maintenance costs associated with traditional particle-stacking ceramic membranes in water treatment. Using halloysite nanotubes as the membrane layer raw material, a novel ceramic nanofiber membrane with multiple confined spaces is constructed, and highly catalytically active multi-component transition metal oxides are uniformly loaded onto the surface and interior of this multi-confined ceramic nanofiber membrane. This multi-confined catalytic ceramic nanofiber membrane not only exhibits ultra-high membrane separation performance in actual water treatment, but it can also act as billions of "Fenton-like nanoreactors," simultaneously achieving efficient physical separation of traditional organic pollutants and efficient oxidative removal of new pollutants during membrane filtration. This overcomes many drawbacks of traditional Fenton-like advanced oxidation technologies based on catalytic ceramic membranes in water treatment.

[0075] The above description provides a further detailed explanation of the present invention in conjunction with specific / preferred embodiments, and it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various substitutions or modifications can be made to these described embodiments without departing from the concept of the present invention, and all such substitutions or modifications should be considered within the scope of protection of the present invention. In the description of this specification, the reference to terms such as "an embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples," etc., indicates that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any suitable manner in one or more embodiments or examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions, and modifications can be made herein without departing from the scope of protection of the patent application.

Claims

1. A multiple confined catalytic ceramic nanofiber membrane, characterized in that, The multi-confined catalytic ceramic nanofiber membrane is an asymmetric planar ceramic membrane, comprising a porous ceramic membrane support, halloysite nanotube layers, and a catalyst with Fenton-like catalytic activity. The halloysite nanotube layers are attached to the surface of the porous ceramic membrane support, and the catalyst is loaded on the surface and within the pores of the porous ceramic membrane support. The catalyst is also loaded on the surface and within the pores of the halloysite nanotubes in the halloysite nanotube layers. The catalyst is a multi-element transition metal oxide, specifically at least one of CuMnO, FeMnO, TiMnO, ZnMnO, CuFeMnO, CuZnMnO, CuTiMnO, and TiMnFeO. The halloysite nanotube layers are formed from halloysite nanotubes, which are open-ended tubular structures formed by the curling of lamellar sheets. The tube walls are composed of several layers of stacked structural units. The surface of the halloysite nanotubes is rich in hydroxyl groups and exhibits strong hydrophilicity. The spacing between the lamellar sheets of the halloysite nanotubes is 7-10 mm. The diameter of the central cavity pore of the halloysite nanotube is 10-30 nm, thus the halloysite nanotube layer simultaneously possesses angstrom-scale and nanometer-scale confined space.

2. The multi-confined catalytic ceramic nanofiber membrane as described in claim 1, characterized in that, The thickness of the halloysite nanotube layer is 10-50 μm; the outer diameter of the halloysite nanotube is 30-190 nm; and the length of the halloysite nanotube is 0.02-30 μm.

3. The multiple confined catalytic ceramic nanofibrous membrane of claim 1, wherein, In the multi-confined catalytic ceramic nanofiber membrane, the catalyst loading is 0.5 wt%-10 wt%; the catalyst particle size is 5-20 nm.

4. The multiple confined catalytic ceramic nanofibrous membrane of claim 1, wherein, The porous ceramic membrane support material is aluminum oxide, or a mixture of aluminum oxide and silicon dioxide; the pore size of the porous ceramic membrane support is 1-3 μm; and the thickness of the porous ceramic membrane support is 1-2 mm.

5. A method for preparing the multiple confined catalytic ceramic nanofiber membrane according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Clean the porous ceramic membrane support for later use; (2) The halloysite nanotube powder, dispersant and stabilizer are mixed evenly in ultrapure water to prepare the film slurry; (3) The porous ceramic membrane support obtained in step (1) is immersed in the membrane slurry obtained in step (2) for slurry coating, and then sintered at high temperature to form a membrane. (4) Immerse the membrane obtained in step (3) into the precursor solution of the catalyst, so that the precursor solution is fully adsorbed onto the membrane surface and fills the membrane pores to load the catalyst, and then sinter at high temperature to obtain the multi-confined catalytic ceramic nanofiber membrane.

6. The production method according to claim 5, wherein In the film slurry of step (2), the content of halloysite nanotube powder is 1 wt%-6 wt%, the content of dispersant is 1 wt%-2 wt%, the content of stabilizer is 2 wt%-3 wt%, and the balance is water; the dispersant is at least one of sodium pyrophosphate, trisodium phosphate, tetrasodium phosphate, sodium hexametaphosphate, sodium metasilicate, and sodium disilicate; the stabilizer is at least one of methylcellulose and carboxymethylcellulose; and the halloysite nanotube powder is natural halloysite nanotubes.

7. The production method according to claim 5, wherein The high-temperature sintering processes in steps (3) and (4) are each independent: heating to 500-800℃ at a heating rate of 2-5℃ / min and calcining for 2-4 hours.

8. The production method according to claim 5, wherein The process of slurry coating in step (3) is as follows: the porous ceramic membrane support obtained in step (1) is immersed in the membrane slurry obtained in step (2) at least once. After each slurry immersion, it is dried at 20-25℃ for 10-12 h. After forming a membrane of a predetermined thickness, it is dried at 50-90℃ for 10-12 h. The number of slurry immersions is 1-10 times. The time for each slurry immersion is 5-20 s. The process of loading the catalyst in step (4) is as follows: at room temperature, the membrane obtained in step (3) is immersed in the precursor solution of the catalyst at least once. After each immersion, it is dried at 20-25°C for 10-12 h, so that the precursor solution is fully adsorbed onto the surface of the membrane pores and fills the membrane pores to load the predetermined amount of catalyst. The membrane is then dried at 50-90°C for 10-12 h. The number of immersions is 1-5 times. The time for each immersion is 0.5-12 h.

9. The preparation method according to claim 5, characterized in that, The precursor solution in step (4) contains transition metal ions and an alkaline precipitant. The concentration of the transition metal ions is 0.01-1.5 mol / L, and the concentration of the alkaline precipitant is 0.015-2.5 mol / L. The ratio of the concentrations of each transition metal ion in the precursor solution conforms to the metal element ratio of spinel AB2O4 or perovskite ABO3 metal oxide. The alkaline precipitant is at least one of urea and sodium hydroxide.

10. Use of the multiple confined catalytic ceramic nanofibrous membrane according to any one of claims 1 to 4 in water treatment, characterized in that, The multi-confined catalytic ceramic nanofiber membrane achieves efficient removal of pollutants in water treatment through a coupled Fenton-like reaction; the application includes the following steps: S1. The multi-confined catalytic ceramic nanofiber membrane is installed in the membrane tank, and the water to be treated is continuously filtered using a constant flux dead-end filtration method; the membrane flux is 20-120 L / (m²). 2 ·h); S2. During the membrane filtration process, an oxidant is added to the membrane tank to initiate a Fenton-like reaction catalyzed by the multi-confined catalytic ceramic nanofiber membrane, thereby enhancing the removal of pollutants from the water; the oxidant is at least one of hydrogen peroxide and persulfate; the dosage of the oxidant is 0.01-20 mM.

11. The application as described in claim 10, characterized in that, The process also includes step S3, in which in-situ ozone aeration is performed at the bottom of the multi-confined catalytic ceramic nanofiber membrane during the membrane filtration process, with an air-to-water ratio of 3:1-8:1 and an in-situ ozone dosage of 0.5-20 mg / L, to further enhance the removal of pollutants from the water.

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