Multi-confinement catalytic ceramic nanofiber membrane as well as preparation method and application thereof

Abstract

The invention discloses a multi-confinement catalytic ceramic nanofiber membrane as well as a preparation method and application thereof, the multi-confinement catalytic ceramic nanofiber membrane is an asymmetric flat ceramic membrane, and comprises a porous ceramic membrane support body, a 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 body, the catalyst is loaded on the surface of the porous ceramic membrane support body and in pores of the porous ceramic membrane support body, and the catalyst is also loaded on the surface of a halloysite nanotube in the halloysite nanotube layer and in pores of the halloysite nanotube. The multi-confinement catalytic ceramic nanofiber membrane disclosed by the invention is extremely strong in hydrophilicity, high in membrane flux, high in Fenton-like catalytic activity, capable of efficiently oxidizing and removing new pollutants in water, strong in catalyst stability and capable of being widely applied to various water treatments of medical wastewater and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic membranes, and in particular to a multi-confined catalytic ceramic nanofiber membrane and a preparation method and application thereof. Background Art

[0002] In recent years, with the rapid development of the economy, water pollution, especially the pollution of new water pollutants, has become increasingly serious. The research and development and practical application of efficient removal technologies for 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 active oxygen species produced by Fenton-like systems, and are considered to be a promising new pollutant control technology in the new water treatment era. However, traditional Fenton-like reactions still have many technical bottlenecks that need to be overcome, such as limited catalytic activity of traditional transition metal oxides, low utilization of active oxygen species, agglomeration of powder catalyst particles, and difficulty in catalyst recovery and regeneration.

[0003] Ceramic membranes, such as inorganic ceramic membranes with aluminum oxide as the main component, have strong antioxidant properties and can be used as excellent carriers of transition metal oxide catalysts. Loading the catalyst onto the nano-ceramic membrane carrier can not only easily solve the problem of powder catalyst agglomeration and recovery difficulties, but the nano-ceramic membrane pores can also be used as nano-reactors to enhance the mass transfer efficiency of active oxygen species to organic pollutants in Fenton-like reactions, greatly improving the utilization rate of active oxygen species and the removal rate of new pollutants. However, at present, catalytic ceramic membranes are still mainly particle-stacked ceramic membranes loaded with traditional monocyclic transition metal oxide catalysts such as iron oxides and manganese oxides. There are still disadvantages such as low catalytic efficiency, poor catalytic stability, low membrane porosity, high transmembrane pressure, serious membrane pollution during long-term operation, and high operation and maintenance costs that need to be overcome.

[0004] It should be noted that the information disclosed in the above background technology section is only used for understanding the background of the present application, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the invention

[0005] In order to make up for the deficiencies of the prior art, the present invention provides a multi-confined catalytic ceramic nanofiber membrane and a preparation method and application thereof.

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

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

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

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

[0010] (2) mixing halloysite nanotube powder, a dispersant, and a stabilizer in ultrapure water to obtain a membrane slurry;

[0011] (3) immersing the porous ceramic membrane support obtained in step (1) into the membrane layer slurry obtained in step (2) to form a membrane, and then sintering at high temperature to form a membrane;

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

[0013] In the third aspect, an application of a multi-confined catalytic ceramic nanofiber membrane in water treatment is provided, wherein the multi-confined catalytic ceramic nanofiber membrane achieves efficient removal of pollutants, especially new pollutants, in water treatment by coupling Fenton-like reactions.

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

[0015] In the present invention, halloysite, as a natural hollow tubular nanomaterial, has the advantages of abundant natural content, low cost, high biocompatibility, strong thermal stability, high specific surface area, and extremely strong hydrophilicity. The present invention uses it to construct a new ceramic fiber membrane. The new ceramic nanofiber membrane constructed based on halloysite nanotubes not only has a low preparation cost, but also has a higher porosity and a higher membrane flux than the particle stacked ceramic membrane, and can be used as an excellent carrier for the catalyst. Multi-walled halloysite has a central nanoscale confined space and an angstrom-level confined space between multi-walled layers, which can provide multiple confined reaction spaces for catalytic reactions, and can improve the molecular mass transfer efficiency and new pollutant removal rate during Fenton-like catalytic reactions. The nanoscale confined space of halloysite nanotubes can also load catalysts more stably and improve the catalytic stability of the catalytic membrane. The multi-confined catalytic ceramic nanofiber membrane of the present invention is extremely hydrophilic and has a high membrane flux, and can be widely used in various water treatments such as medical wastewater. Specifically, the present invention has the following advantages:

[0016] (1) Multiple confined catalysis: The multiple confined catalytic ceramic nanofiber membrane of the present invention is mainly constructed of multi-walled halloysite nanotubes, which not only increases the porosity and water permeability of the ceramic membrane, but also the nano-confined space inside the pores of the halloysite nanotubes and the angstrom-level confined space between the multi-walled layers provide multiple confined catalytic reaction spaces for Fenton-like reactions. Multiple confined spaces help to improve the mass transfer efficiency and utilization rate of active oxygen species in Fenton-like reactions, thereby improving the oxidation removal efficiency of new pollutants, and effectively overcoming the disadvantage of low utilization rate of active oxygen species in open Fenton-like systems due to 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 the halloysite nanotubes has stronger catalytic stability and has the advantages of being difficult to dissolve and fall off.

[0018] (3) High catalytic activity: In a preferred embodiment, the multi-confined catalytic ceramic nanofiber membrane is loaded with a multi-element transition metal oxide with high catalytic activity, which can efficiently catalyze a variety of oxidants widely used in water treatment, such as ozone, hydrogen peroxide, and persulfate. The membrane has high catalytic activity for a variety of Fenton-like advanced oxidation processes, such as hydrogen peroxide, ozone, persulfate, ozone / hydrogen peroxide, hydrogen peroxide / persulfate, but not limited to these, thereby achieving the dual purpose of enhanced removal of new pollutants in actual water treatment and membrane pollution control in the process of coupling with Fenton-like advanced oxidation reactions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a microscopic 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 microscope image at the magnification of the circle in the middle.

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

[0022] Figure 4 This is the result of the multi-confined catalytic ceramic nanofiber membrane in Example 3 of the present invention catalyzing hydrogen peroxide to remove paracetamol in water. DETAILED DESCRIPTION

[0023] The following is a detailed description of the embodiments of the present invention. It should be emphasized that the following description is only exemplary and is not intended to limit the scope of the present invention and its application. In the absence of conflict, the embodiments and features in the embodiments of this application can be combined with each other. Herein, "room temperature" refers to 20-25°C.

[0024] A specific embodiment of the present invention provides a multi-confined catalytic ceramic nanofiber membrane, which is an asymmetric flat ceramic membrane, including a porous ceramic membrane support, a halloysite nanotube layer and a catalyst with Fenton-like catalytic activity, wherein the halloysite nanotube layer is attached to the surface of the porous ceramic membrane support, the catalyst is loaded on the surface and pores of the porous ceramic membrane support, and the catalyst is also loaded on the surface and pores of the halloysite nanotubes in the halloysite nanotube layer.

[0025] The multi-confined catalytic ceramic nanofiber membrane is mainly constructed of halloysite nanotubes. Halloysite nanotubes are hollow tubular structures with open ends formed by curling sheets. The tube wall is stacked with several layers of layered structural units. The surface of the halloysite nanotubes is rich in hydroxyl groups and is extremely hydrophilic, which is beneficial to improving the membrane flux. The halloysite nanotube layer formed by halloysite nanotubes has both angstrom-level (the spacing between the tube wall sheets of the halloysite nanotube is at the angstrom level) and nanometer-level (the pore size of the central cavity pore of the halloysite nanotube is at the nanometer level) confined 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 diameter of the central hole of the halloysite nanotube is 10-30 nm, the outer diameter of the halloysite nanotube is 30-190 nm, the length of the halloysite nanotube is 0.02-30 μm; the spacing between the tube wall sheets of the halloysite nanotube is

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

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

[0029] In some embodiments, the catalyst has a particle size of 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 porous ceramic membrane support has a thickness of 1-2 mm.

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

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

[0035] (1) Clean the porous ceramic membrane support and set it aside; preferably, the commercial porous ceramic membrane support can be cut into the required size, and then ultrasonically cleaned in ultrapure water for 20-60 minutes, dried at 80-100° C. for 5-10 hours, and set it aside.

[0036] (2) mixing the halloysite nanotube powder, dispersant and stabilizer in ultrapure water to obtain a membrane slurry; preferably, mixing the halloysite nanotube powder, dispersant and stabilizer in ultrapure water to obtain a membrane slurry by ultrasonication for 30-60 minutes;

[0037] (3) immersing the porous ceramic membrane support obtained in step (1) into the membrane layer slurry obtained in step (2) to form a membrane, and then sintering at a high temperature to form a membrane, wherein the membrane includes the porous ceramic membrane support and the halloysite nanotube layer attached to the porous ceramic membrane support;

[0038] (4) Immersing the membrane obtained in step (3) into a catalyst precursor solution, 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 the halloysite nanotube layer) to load the catalyst, and then sintering at high temperature to obtain the multi-confined catalytic ceramic nanofiber membrane.

[0039] In the above embodiment, on a porous ceramic membrane support, halloysite nanotubes are used as the main membrane layer raw material, and a slurry coating-high temperature sintering-impregnation modification-high temperature sintering process is adopted to produce a new generation of multi-confined catalytic ceramic nanofiber membrane with high flux and high catalytic activity.

[0040] In some embodiments, in the membrane layer slurry of step (2), the content of halloysite nanotube powder 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 of 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 methyl cellulose and carboxymethyl cellulose.

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

[0044] In some embodiments, the high temperature sintering processes in step (3) and step (4) are independently as follows: heating to 500-800° C. at a heating rate of 2-5° C. / min and calcining for 2-4 hours.

[0045] In some embodiments, the process of slurry coating in step (3) is: immersing the porous ceramic membrane support obtained in step (1) into the membrane layer slurry obtained in step (2) for at least one slurry, drying at 20-25°C for 10-12 hours after each slurry immersion, and after forming a membrane layer of a predetermined thickness, drying 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 loading the catalyst in step (4) is: at room temperature,The membrane obtained in step (3) is immersed in the precursor solution of the catalyst at least once, and dried at 20-25°C for 10-12h after each immersion, so that the precursor solution is fully adsorbed onto the membrane pore surface and fills the membrane pores to load a predetermined amount of catalyst, and dried at 50-90°C for 10-12h; preferably, the number of immersions is 1-5 times; preferably, the time of a single immersion is 0.5-12h.

[0047] In some embodiments, the precursor solution in step (4) contains transition metal ions and an alkaline precipitant, the transition metal ion concentration is 0.01-1.5 mol / L, and contains binary, ternary or polybasic metal ions such as Cu, Fe, Mn, Zn, Ti, etc., and the alkaline precipitant concentration 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 is consistent with the spinel AB 2 O 4 Or perovskite ABO 3 The metal element ratio of metal oxide.

[0049] A specific embodiment of 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 by coupling Fenton-like reactions.

[0050] In the above application, the multi-confined catalytic ceramic nanofiber membrane is used in conjunction with oxidants such as hydrogen peroxide, ozone, and persulfate to construct a Fenton-like advanced oxidation and ceramic membrane filtration integrated system, which efficiently oxidizes and degrades conventional organic pollutants and new pollutants while separating pollutants through membrane filtration, thereby achieving efficient purification of various water and sewage such as drinking water, urban domestic sewage, and medical wastewater. Specifically preferably, in the multi-confined catalytic ceramic nanofiber membrane, a multi-Fenton-like metal oxide catalyst with high catalytic activity is loaded on the halloysite nanotubes, which can more efficiently decompose oxidants such as hydrogen peroxide, ozone, and persulfate to produce active oxygen species such as hydroxyl radicals, singlet oxygen or superoxide radicals, thereby stimulating continuous Fenton-like reactions, and the angstrom-level and nanoscale multi-confined spaces contained in the multi-confined catalytic ceramic nanofiber membrane can shorten the mass transfer distance between active oxygen species and target pollutants during the Fenton-like reaction, improve the molecular mass transfer efficiency, and thus enhance the removal of pollutants (especially new pollutants) in water.

[0051] In some embodiments, the application comprises the following steps:

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

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

[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, the gas-water ratio is 3:1-8:1, and the in-situ ozone gas dosage is 0.5-20 mg / L, so as to further enhance the removal of pollutants (especially new pollutants) in the water.

[0055] Among them, the new pollutants include but are not limited to the following types of new pollutants commonly found in natural water bodies: ofloxacin, ciprofloxacin, tylosin, paracetamol, 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 specific embodiments of the present invention are further described below.

[0058] Example 1

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

[0060] (1) Preparation of porous ceramic membrane support: Cut the commercial aluminum oxide porous ceramic membrane support into a fixed size, clean it in ultrapure water for 30 min, dry it at 80° C. for 6 h, and set it aside;

[0061] (2) preparing membrane slurry: 4 wt % of halloysite nanotube powder, 1 wt % of sodium hexametaphosphate dispersant, and 2 wt % of carboxymethyl cellulose dispersant were mixed evenly in 93 wt % of ultrapure water, and then ultrasonicated for 30 min to prepare membrane slurry for later use;

[0062] (3) Primary slurry coating: The porous ceramic membrane support treated in step (1) is immersed in the membrane layer slurry prepared in step (2) for 15 seconds, dried at 25°C for 12 hours, and oven-dried at 80°C for 12 hours.

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

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

[0065] (6) The completely impregnated membrane was dried at 25°C for 12 h, and then dried at 80°C for 12 h. The dried membrane was heated to 600°C in a high-temperature furnace at a heating rate of 5°C / min and calcined for 2 h 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 catalyst and a catalyst-loaded halloysite nanotube layer 2 attached to the surface of the porous ceramic membrane support 1 loaded with catalyst, and the average thickness of the catalyst-loaded halloysite nanotube layer 2 is 10 μm. Figure 2 As shown, the diameter of the central hole of the halloysite nanotube is 10-30 nm, the outer diameter of the halloysite nanotube is 30-190 nm, the length of the halloysite nanotube is 0.02-30 μm, and the spacing between the tube wall sheets of the halloysite nanotube is The particle size of the loaded catalyst is between 5 and 20 nm. As shown in Table 1 below, the multi-confined catalytic ceramic nanofiber membrane is mainly composed of six elements: O, Al, Si, Mn, Fe, and Cu. 2 ·h), the pure water permeability of the multi-confined catalytic ceramic nanofiber membrane was about 181L / (m 2 ·h·bar), the pure water permeability of the multi-confined catalytic ceramic nanofiber membrane is significantly higher than that of the traditional particle stacking ceramic membrane.

[0067] Table 1

[0068]

[0069]

[0070] Example 2

[0071] The multi-confined catalytic ceramic nanofiber membrane provided in Example 1 is used for water treatment. The multi-confined catalytic ceramic nanofiber membrane can achieve enhanced removal of new pollutants in water by coupling Fenton-like reactions. Specifically, Figure 3 As shown, a constant flux dead-end filtration method is used, with a flow rate of 40L / (m 2 ·h) of membrane flux to treat water containing 1mg / L ofloxacin. When the hydrogen peroxide dosage was 5mM, more than 99% ofloxacin in the membrane effluent could be removed. This result confirmed that the catalytic membrane prepared by the present invention has strong Fenton-like catalytic activity and can effectively enhance the removal of new pollutants in water. After 24h of continuous membrane filtration, the removal rate of ofloxacin in the membrane effluent still exceeded 99%, confirming that the multi-confined catalytic ceramic nanofiber membrane has strong catalytic stability.

[0072] Example 3

[0073] The multi-confined catalytic ceramic nanofiber membrane provided in Example 1 is used for water treatment. The multi-confined catalytic ceramic nanofiber membrane can achieve enhanced removal of new pollutants in water by coupling Fenton-like reactions. Specifically, Figure 4 As shown, a constant flux dead-end filtration method is used, with a flow rate of 40L / (m 2 h) to carry out continuous membrane filtration experiments, treating water containing 1.5 mg / L paracetamol, when the hydrogen peroxide dosage is 5 mM, the paracetamol removal effect of more than 99.9% in the membrane effluent can be achieved. This result confirms that the catalytic membrane prepared by the present invention has strong Fenton-like catalytic activity and can effectively enhance the removal of new pollutants represented by paracetamol in water. After continuous membrane filtration for 48 hours, the removal rate of paracetamol in the membrane effluent still exceeds 99.9%, confirming that the multi-confined catalytic ceramic nanofiber membrane has strong catalytic stability for long-term operation.

[0074] The present invention overcomes the problems of low catalytic efficiency, poor catalytic stability, low membrane porosity, high transmembrane pressure, serious membrane pollution in long-term operation, and high operation and maintenance costs of traditional particle-stacked catalytic ceramic membranes in water treatment. With halloysite nanotubes as the raw material of the membrane layer, a new ceramic nanofiber membrane with multiple confined spaces is constructed, and multi-element transition metal oxides with high catalytic activity are uniformly loaded on the surface and inside of the ceramic nanofiber membrane with multiple confined spaces. The multiple confined catalytic ceramic nanofiber membrane not only has ultra-high membrane separation performance in actual water treatment, but also can be used as hundreds of millions of "Fenton-like nanoreactors" to simultaneously realize the efficient physical separation of traditional organic pollutants and the efficient oxidation removal of new pollutants in the membrane filtration process, thereby overcoming many disadvantages of the traditional Fenton-like advanced oxidation technology based on catalytic ceramic membranes in water treatment.

[0075] The above content is a further detailed description of the present invention in combination with specific / preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, without departing from the concept of the present invention, it can also make several substitutions or modifications to these described embodiments, and these substitutions or modifications should be regarded as belonging to the protection scope of the present invention. In the description of this specification, the description of the reference terms "an embodiment", "some embodiments", "preferred embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily target the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In the absence of mutual contradiction, those skilled in the art can combine and combine 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 multi-confined catalytic ceramic nanofiber membrane, characterized in that: The multi-confined catalytic ceramic nanofiber membrane is an asymmetric flat ceramic membrane, including a porous ceramic membrane support, a 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 pores of the porous ceramic membrane support. The catalyst is also loaded on the surface and pores of the halloysite nanotubes in the halloysite nanotube layer.

2. The multi-confined catalytic ceramic nanofiber membrane according to claim 1, characterized in that: The thickness of the halloysite nanotube layer is 10-50 μm; the diameter of the central hole of the halloysite nanotube is 10-30 nm, the outer diameter of the halloysite nanotube is 30-190 nm, the length of the halloysite nanotube is 0.02-30 μm; the spacing between the tube wall sheets of the halloysite nanotube is 3. The multi-confined catalytic ceramic nanofiber membrane according to claim 1, characterized in that: The catalyst is a multi-continent transition metal oxide; the multi-continent transition metal oxide is at least one of CuMnO, FeMnO, TiMnO, ZnMnO, CuFeMnO, CuZnMnO, CuTiMnO, and TiMnFeO; preferably, in the multi-confined catalytic ceramic nanofiber membrane, the loading amount of the catalyst is 0.5wt%-10wt%; preferably, the particle size of the catalyst is 5-20nm.

4. The multi-confined catalytic ceramic nanofiber membrane according to claim 1, characterized in that: The porous ceramic membrane support material is aluminum oxide, or a mixture of aluminum oxide and silicon dioxide; preferably, the pore size of the porous ceramic membrane support is 1-3 μm; preferably, the thickness of the porous ceramic membrane support is 1-2 mm.

5. A method for preparing a multi-confined catalytic ceramic nanofiber membrane, characterized in that: The steps include: (1) cleaning the porous ceramic membrane support for later use; (2) mixing halloysite nanotube powder, a dispersant, and a stabilizer in ultrapure water to obtain a membrane slurry; (3) immersing the porous ceramic membrane support obtained in step (1) into the membrane layer slurry obtained in step (2) to form a membrane, and then sintering at high temperature to form a membrane; (4) Immersing the membrane obtained in step (3) into a catalyst precursor solution so that the precursor solution is fully adsorbed onto the membrane surface and fills the membrane pores to load the catalyst, and then sintering at high temperature to obtain the multi-confined catalytic ceramic nanofiber membrane.

6. The preparation method according to claim 5, characterized in that: In the membrane slurry of step (2), the content of halloysite nanotube powder is 1wt%-6wt%, the content of dispersant is 1wt%-2wt%, the content of stabilizer is 2wt%-3wt%, and the balance is water; Preferably, the dispersant is at least one of sodium hexametaphosphate, sodium pyrophosphate, trisodium phosphate, tetrasodium phosphate, sodium hexametaphosphate, sodium metasilicate, and sodium disilicate; preferably, the stabilizer is at least one of methyl cellulose and carboxymethyl cellulose; preferably, the halloysite nanotube powder is natural halloysite nanotube.

7. The preparation method according to claim 5, characterized in that: The high temperature sintering processes in step (3) and step (4) are independently as follows: heating to 500-800° C. at a heating rate of 2-5° C. / min and calcining for 2-4 hours.

8. The preparation method according to claim 5, characterized in that: 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 layer slurry obtained in step (2) for at least one slurry, and after each slurry immersion, it is dried at 20-25°C for 10-12 hours, and after forming a membrane layer of a predetermined thickness, it is dried at 50-90°C for 10-12 hours; preferably, the number of slurry immersions is 1-10 times; preferably, the time of a single slurry immersion is 5-20 seconds; The process of loading the catalyst in step (4) is as follows: at room temperature, immersing the membrane obtained in step (3) into a catalyst precursor solution for at least one time, and drying at 20-25°C for 10-12 hours after each immersion, so that the precursor solution is fully adsorbed onto the membrane pore surface and fills the membrane pores to load a predetermined amount of catalyst, and drying at 50-90°C for 10-12 hours; preferably, the number of immersions is 1-5 times; preferably, the time for a single immersion is 0.5-12 hours.

9. The preparation method according to claim 5, characterized in that: The precursor solution in step (4) contains transition metal ions and alkaline precipitant, the transition metal ion concentration is 0.01-1.5 mol / L, and the alkaline precipitant concentration is 0.015-2.5 mol / L; preferably, the concentration ratio 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. Application of a multi-confined catalytic ceramic nanofiber membrane in water treatment, characterized in that: The multi-confined catalytic ceramic nanofiber membrane achieves efficient removal of pollutants, especially new pollutants, in water treatment by coupling Fenton-like reactions; preferably, the application comprises the following steps: S1. The multi-confined catalytic ceramic nanofiber membrane is arranged in the membrane pool, and the water to be treated is continuously filtered by a constant flux dead-end filtration method; preferably, the membrane flux is 20-120 L / (m 2 h); S2. During the membrane filtration process, an oxidant is added to the membrane pool to initiate a Fenton-like reaction catalyzed by the multi-confined catalytic ceramic nanofiber membrane to enhance the removal of pollutants in water, especially new pollutants; preferably, the oxidant is at least one of hydrogen peroxide and persulfate; preferably, the dosage of the oxidant is 0.01-20 mM; Preferably, step S3 is also included, during the membrane filtration process, in-situ ozone aeration is performed at the bottom of the multiple confined catalytic ceramic nanofiber membrane, the gas-water ratio is 3:1-8:1, and the in-situ ozone gas dosage is 0.5-20 mg / L, so as to further enhance the removal of pollutants in the water, especially new pollutants.

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