MXene-based / ceramic composite nanofiltration membrane as well as preparation method and application thereof

Abstract

The invention relates to an MXene-based / ceramic composite nanofiltration membrane as well as a preparation method and application thereof, the preparation method comprises the following steps: S1, providing Ti3AlC2, mixing Ti3AlC2 with hydrofluoric acid under a heating condition, carrying out etching reaction, and stripping to obtain a Ti3C2Tx MXene nanosheet; s2, depositing the Ti < 3 > C < 2 > T < x > MXene nanosheets on the surface of a ceramic membrane support body, drying, and carrying out thermal crosslinking to obtain an MXene-based / ceramic composite nanofiltration membrane; wherein T is at least one of-F,-O and-OH, and x is 0-2. According to the technical scheme, Ti3AlC2 is etched with hydrofluoric acid to obtain MXene nanosheets, the MXene nanosheets are deposited on the inner surface of the ceramic membrane supporting body, the obtained composite nanofiltration membrane can show excellent filtering performance, the macroporous defect of the ceramic supporting body is modified, an additional transition layer is not needed, the technological process is simplified, and the production efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanofiltration membrane, in particular to a MXene-based / ceramic composite nanofiltration membrane and a preparation method and application thereof. BACKGROUND

[0002] As an important separation material, nanofiltration membrane has a wide range of applications in water treatment, food industry, pharmaceutical manufacturing and chemical separation. It can effectively remove dissolved salts, small molecule organic matter and heavy metal ions, and plays a key role in industrial wastewater deep treatment, drinking water purification, food concentration and drug purification. Traditional nanofiltration membranes are mainly made of polymer materials such as polyether sulfone (PES), polyvinylidene fluoride (PVDF) and polyamide (PA). These materials have good separation performance in conventional environments, but they are prone to degradation or structural deterioration under high temperature, high pressure, strong acid and strong base and strong oxidation conditions, thereby limiting their use range. In addition, the anti-pollution ability of polymer membranes is weak, and they are easily affected by organic pollutants, biological fouling and inorganic deposition, which leads to performance degradation and shortens the service life.

[0003] In contrast, ceramic membranes are considered an ideal choice for nanofiltration separation in harsh environments due to their excellent chemical stability, high temperature resistance, mechanical damage resistance and long service life. Ceramic nanofiltration membranes are usually made of inorganic materials such as aluminum oxide (Al2O3), zirconium oxide (ZrO2) and titanium dioxide (TiO2), which can operate stably in high temperature, high pressure, strong acid, strong base, organic solvent and strong oxidation medium for a long time, and are widely used in wastewater treatment, food processing, biopharmaceuticals, catalytic separation and gas purification. However, the preparation process of traditional ceramic membranes is complex, usually involving sol-gel method, phase inversion method or sintering method, etc. High-temperature sintering is required during the preparation process, resulting in high production cost. SUMMARY

[0004] Based on the above description, the present application provides a MXene-based / ceramic composite nanofiltration membrane and a preparation method and application thereof to solve the technical problem of how to simplify the preparation method of the composite nanofiltration membrane.

[0005] The technical solution of the present application to solve the above technical problem is as follows: The present application provides a preparation method of a MXene-based / ceramic composite nanofiltration membrane, comprising: S1. providing Ti3AlC2, mixing with hydrofluoric acid under heating conditions to occur etching reaction, peeling off to obtain Ti3C2T x MXene nanosheet; S2. depositing Ti3C2T x MXene nanosheet to the surface of the ceramic membrane support, drying, heat crosslinking to obtain a MXene-based / ceramic composite nanofiltration membrane; T is at least one of -F, -O and -OH, and x is 0-2.

[0006] Further, step S1 comprises: dissolving LiF in HCl solution to generate HF, adding Ti3AlC2 precursor, water bath heating, peeling to obtain Ti3C2T x MXene nanosheets; The mass ratio of LiF to Ti3AlC2 is 1:(0.8-1.2), and the concentration of HCl is 3-9 mol / L.

[0007] Further, step S2 comprises: loading the MXene nanosheets or mixture thereof on the surface of the ceramic support by vacuum or pressure-assisted suction filtration, drying, and heat treatment to obtain a MXene-based / ceramic composite nanofiltration membrane.

[0008] Further, the structure of the ceramic support is sheet type, single tube, hollow fiber or multi-channel structure; and / or, The material of the ceramic support comprises at least one of Al2O3, ZrO2 and TiO2; and / or, The average pore size of the ceramic support ranges from 20 to 5000 nm.

[0009] Further, in step S2: The lateral size of the MXene nanosheets is 100-5000 nm, and the loading amount of the MXene nanosheets on the surface of the ceramic support is 0.01-0.1 mg / cm 2 .

[0010] Further, in step S2: the drying temperature is 25-60℃, and the drying time is 2-12 h; and / or, The heat treatment temperature is 25-600℃, the heating rate is 0.5-10℃ / min, and the holding time is 1 min-5 h.

[0011] Further, step S1 comprises: S11. dissolving LiF in HCl solution to generate HF, adding Ti3AlC2 precursor, water bath heating, peeling to obtain Ti3C2T x MXene nanosheets; S12. providing a CNT dispersion liquid, mixing the Ti3C2T x MXene nanosheets with the CNT dispersion liquid, and ultrasonicating to obtain a MXene-CNT dispersion liquid; Step S2 comprises: The MXene-CNT dispersion liquid is loaded on the surface of the ceramic support by vacuum or pressure-assisted suction filtration, dried, and heat treated to obtain a MXene-based / ceramic composite nanofiltration membrane.

[0012] Further, in step S12, the Ti3C2T x The mass ratio of the MXene nanosheet to the CNT dispersion liquid is (3-5):1.

[0013] The application further provides a MXene-based / ceramic composite nanofiltration membrane prepared by the preparation method of the MXene-based / ceramic composite nanofiltration membrane.

[0014] The application further provides application of the MXene-based / ceramic composite nanofiltration membrane in nanofiltration.

[0015] Compared with the prior art, the technical scheme of the application has the following beneficial technical effects: 1. The application utilizes the excellent lateral size of MXene to modify the macropore defects of the ceramic support, without the need for an additional transition layer, thereby greatly simplifying the preparation process flow, reducing the complexity of the production steps, and significantly improving the overall production efficiency. Since the production and integration process of the transition layer is omitted, the method can not only reduce the production cost, but also ensure the high consistency and reliability of the composite nanofiltration membrane.

[0016] 2. The application effectively adjusts the interlayer spacing by the hydroxyl thermal crosslinking dehydration reaction of the MXene film material, thereby precisely adjusting the spacing between the MXene films. This regulation mode provides a solid foundation for improving the separation precision of the nanofiltration membrane. Specifically, by controlling the heat treatment conditions, the interlayer distance of the MXene can be finely adjusted to make it more suitable for the filtration and separation requirements of specific substances. This feature enables the prepared nanofiltration membrane to more accurately distinguish between molecules of different sizes or charges when facing complex mixtures, thereby achieving high-efficiency separation effect.

[0017] 3. The application generates TiO2 nanoparticles in situ during the heat-induced process by means of the variable titanium atoms of the MXene film material, constructs a super-smooth TiO2@MXene hydrophilic nanofiltration separation layer, improves the hydrophilicity of the membrane surface, reduces the deposition of pollutants on the membrane surface, and enhances the anti-pollution performance of the membrane. In addition, the presence of TiO2 nanoparticles further optimizes the physical and chemical properties of the nanofiltration membrane, endows it with stronger mechanical strength and higher chemical stability, and ensures that it still maintains high-efficiency and stable separation performance in long-term operation. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1XRD pattern of the MXene film material in Example 1 of the present application; Figure 2 Result graph of the influence of different heat crosslinking temperatures on the separation performance of MXene / ceramic composite nanofiltration membranes for different inorganic salts in Example 1 of the present application; Figure 3 Result graph of the separation performance detection of MXene / ceramic composite nanofiltration membranes for VOSO4 at different heat crosslinking temperatures in Example 1 of the present application; Figure 4 Result graph of the influence detection of different heat crosslinking temperatures on the morphology of MXene-CNT / ceramic composite nanofiltration membranes in Example 2 of the present application; Figure 5 Result graph of the influence detection of different heat crosslinking temperatures on the permeability and retention rate of MXene-CNT / ceramic composite nanofiltration membranes in Example 2 of the present application: Figure 6 Physical morphology change graph of TiO2@MXene / ceramic composite nanofiltration membranes before and after in-situ heat-induced treatment in Example 3 of the present application. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the related drawings. The drawings show embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the specification of the present application herein is only for the purpose of describing specific embodiments and is not intended to limit the present application.

[0021] It can be understood that spatial relationship terms, such as "under", "below", "lower", "underneath", "on", "upper", etc., can be used herein to describe the relationship of one element or feature to another element or feature as shown in the figures. It should be understood that the spatial relationship terms also include different orientations of the device in use and operation in addition to the orientation shown in the figures. For example, if the device in the figures is turned over, the element or feature described as "below" or "under" or "underneath" the other element or feature will be oriented "above" the other element or feature. Therefore, exemplary terms "below" and "under" can include both orientations. In addition, the device can also include other orientations (such as 90 degrees or other orientations), and the spatial description used herein is correspondingly interpreted.

[0022] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connected" should be understood as "electrically connected", "communicatively connected" and the like if the circuits, modules, units and the like connected to each other have transmission of electrical signals or data between each other.

[0023] In recent years, new two-dimensional materials such as MXene, graphene, MOFs, etc. have shown great potential in constructing high-performance nanofiltration membranes due to their unique pore structure, excellent physicochemical properties, and atomic-level thickness. Among them, Ti3C2T x MXene, as a layered two-dimensional transition metal carbide, has attracted much attention in nanofiltration membrane applications due to its high specific surface area, rich surface functional groups (-OH, -F, -O), excellent hydrophilicity, adjustable surface chemistry, good ion sieving ability, and superior mechanical flexibility. The two-dimensional sheet structure of MXene enables it to provide nanoscale confined channels, achieving precise separation of small molecules and ions. However, traditional MXene membrane materials are mostly in self-supporting form or loaded on organic supports, which have problems such as low mechanical strength, insufficient compression resistance, and poor interlayer stability in actual water treatment applications, affecting the reliability of long-term operation. Therefore, by combining MXene with inorganic ceramic membranes, taking advantage of the high strength, corrosion resistance, and stability of ceramic supports, and combining the high-efficiency separation characteristics of MXene, it is expected to construct a new type of high-performance MXene-based / ceramic composite nanofiltration membrane, achieving the synergistic optimization of membrane separation performance and structural stability.

[0024] In recent years, MXene and its composites have shown broad application prospects in water treatment, ion sieving, seawater desalination, and electrochemical separation. For example, MXene-based nanofiltration membranes have shown excellent selectivity in removing heavy metal ions (such as Pb 2+ , Cr 6+ ), and have also shown significant advantages in desalination and organic pollutant separation. In addition, the surface functional groups of MXene can be further optimized through chemical modification, making it have higher anti-pollution ability and durability. Therefore, in-depth study of the microstructure regulation strategy of MXene membrane materials, surface functionalization methods, and their application mechanism in nanofiltration membranes has important scientific research value and engineering application significance.

[0025] The present application is based on the above research background, proposes a high-efficiency and stable preparation method, aiming to construct a high-performance MXene-based / ceramic composite nanofiltration membrane. The method optimizes the interface interaction between MXene and the ceramic support and the membrane layer construction strategy, realizes precise control of the membrane pore size, improves the permeation flux and selectivity, and enhances the mechanical stability and anti-fouling ability of the membrane, thereby expanding its application in high-temperature, strong oxidation and complex water treatment environments.

[0026] Therefore, the present application provides a preparation method of a MXene-based / ceramic composite nanofiltration membrane, comprising: S1. Providing Ti3AlC2, mixing with hydrofluoric acid under heating conditions to occur etching reaction, peeling to obtain Ti3C2T x MXene nanosheets; S2. Depositing Ti3C2T x MXene nanosheets onto the surface of a ceramic membrane support, drying, and heat crosslinking to obtain a MXene-based / ceramic composite nanofiltration membrane; Wherein, T is at least one of -F, -O and -OH, and x is 0-2.

[0027] In the technical solution of the present application, MXene nanosheets are obtained by etching Ti3AlC2 with hydrofluoric acid, and then deposited on the surface of a ceramic membrane support. The obtained composite nanofiltration membrane can exhibit excellent filtration performance, modify the large pore defects of the ceramic support, does not require an additional transition layer, simplifies the process flow, and improves production efficiency. In the process of heat crosslinking, TiO2 nanoparticles are generated in situ from the MXene nanosheets, constructing a super-smooth TiO2@MXene hydrophilic nanofiltration separation layer, improving the hydrophilicity and anti-fouling performance of the membrane.

[0028] It should be noted that during the deposition process, the deposition position of the MXene nanosheets on the ceramic membrane support is not limited, which can be the inner surface or the outer surface. Specifically, in some embodiments of the present application, when the lateral size of the MXene nanosheets is greater than 1000 nm, the MXene nanosheets are deposited on the outer surface.

[0029] Further, step S1 comprises: Dissolving LiF in an HCl solution to generate HF, adding a Ti3AlC2 precursor, water bath heating, peeling to obtain Ti3C2T x MXene nanosheets; Wherein, the mass ratio of LiF to Ti3AlC2 is 1:(0.8-1.2), and the concentration of HCl is 3-9 mol / L.

[0030] Preferably, the mass ratio of LiF to Ti3AlC2 is 1:1.

[0031] Further, step S2 comprises: The MXene nanosheet or mixture thereof is loaded on the surface of the ceramic support by vacuum or pressure-assisted suction filtration, dried, heat treated to obtain a MXene-based / ceramic composite nanofiltration membrane.

[0032] Further, the structure of the ceramic support is sheet type, single tube, hollow fiber or multi-channel structure; and / or, The material of the ceramic support includes at least one of Al2O3, ZrO2 and TiO2; and / or, The average pore size of the ceramic support ranges from 20 to 5000 nm.

[0033] Further, in step S2: The lateral size of the MXene nanosheet is 100-5000 nm, and the loading amount of the MXene nanosheet on the surface of the ceramic support is 0.01-0.1 mg / cm 2 .

[0034] Further, in step S2: the drying temperature is 25-60℃, and the drying time is 2-12 h; and / or, The heat treatment temperature is 25-600℃, the heating rate is 0.5-10℃ / min, and the holding time is 1 min-5 h.

[0035] It should be noted that in the technical solution of the present application, the heat treatment does not need to be carried out in an inert atmosphere, and the heat treatment can be carried out in an air atmosphere; by heat treatment in an air atmosphere, the oxygen in the air can promote the crosslinking between the oxygen-containing functional groups on the surface of MXene, and part of the MXene is oxidized to crosslink with TiO2, so that TiO2 nanoparticles are generated in situ on the surface of MXene, forming a TiO2@MXene composite membrane.

[0036] Further, step S1 comprises: S11. Dissolve LiF in HCl solution to generate HF, add Ti3AlC2 precursor, heat in water bath, peel off to obtain Ti3C2T x MXene nanosheet; S12. Provide a CNT dispersion liquid, mix the Ti3C2T x MXene nanosheet with the CNT dispersion liquid, ultrasonic to obtain a MXene-CNT dispersion liquid; Step S2 comprises: The MXene-CNT dispersion liquid is loaded on the surface of the ceramic support by vacuum or pressure-assisted suction filtration, dried, heat treated to obtain a MXene-based / ceramic composite nanofiltration membrane.

[0037] In the technical scheme of the present application, by adding CNT (carbon nanotube) as an intercalation material, the interlayer nanochannel of MXene can be expanded, and the two can be assembled to form a continuous maze type three-dimensional mass transfer channel, thereby relieving the phenomenon of reduced permeability caused by serious accumulation and narrow interlayer spacing between adjacent MXene nanosheets.

[0038] Further, in step S12, the Ti3C2T x The mass ratio of the MXene nanosheet to the CNT dispersion liquid is (3-5):1.

[0039] The present application also provides a MXene-based / ceramic composite nanofiltration membrane prepared by the preparation method of the MXene-based / ceramic composite nanofiltration membrane.

[0040] In the technical scheme of the present application, the surface color of the MXene-based / ceramic composite nanofiltration membrane changes from dark green to white, and presents an ultra-smooth metal luster, 2D MXene serves as a two-dimensional platform for depositing 0D TiO2, after in-situ heat induction, TiO2 and MXene are connected with each other to form an ultra-smooth, super-hydrophilic and high-permeation 0D-2D TiO2@MXene nanofiltration membrane, which helps to form a continuous and stable hydration layer on the membrane surface during the separation process, effectively prevents pollutants from coalescing on the membrane surface, and improves the anti-fouling performance.

[0041] The present application also provides an application of the MXene-based / ceramic composite nanofiltration membrane in nanofiltration.

[0042] The technical scheme of the present application will be further described in detail in combination with specific embodiments, and it should be understood that the following embodiments are only used to explain the present application, and are not used to limit the present application.

[0043] Embodiment 1 (1) Ti3C2T x Preparation of MXene nanosheet: 6 mol / L hydrochloric acid was placed in a polytetrafluoroethylene reaction kettle liner, and 1 g of lithium fluoride was added to generate hydrofluoric acid to etch the Ti3AlC2 precursor. Then, 1 g of Ti3AlC2 was added to the solution, etched under water bath heating conditions, and subjected to ultrasonic treatment to exfoliate the MXene layer, so as to finally obtain Ti3C2T x MXene nanosheet.

[0044] (2) Preparation of MXene / ceramic composite nanofiltration membrane by heat crosslinking method: A pressure-assisted suction filtration method was used to load 0.01 mg / cm² of Ti3C2T xMXene small nanosheets are deposited on the inner surface of a single-tube ceramic membrane support and dried at 60°C for 2 hours. Subsequently, the membrane is placed in a muffle furnace for thermal crosslinking treatment in an air atmosphere, with the thermal crosslinking temperature set at 200°C, 300°C and 400°C respectively, the heating and cooling rates are both 5°C / min, and the holding time is 1 min. In this process, the hydroxyl groups of the MXene layer undergo thermal crosslinking dehydration reaction to form MXene / ceramic composite nanofiltration membranes with different interlayer spacings.

[0045] Reference Figure 1 As the temperature gradually increases, the diffraction peak of the MXene (002) crystal plane appears in the XRD pattern, and there is no characteristic peak of TiO2, which means that the MXene has good thermal stability in this temperature range and can maintain its unique two-dimensional structural characteristics. According to Bragg's law, the film layer spacing can be calculated. When the temperature increases from 600°C to 400°C, the 2θ angle corresponding to the MXene (002) crystal plane shifts from 6.44° to 6.97°, and the corresponding interlayer spacing is calculated to be reduced from 3.71 Å to 2.68 Å. The decrease in film layer spacing can be attributed to the evaporation of water in the MXene film layer under heat treatment, and the thermal crosslinking dehydration reaction between adjacent MXene layers, which leads to a decrease in interlayer spacing due to the removal of hydroxyl groups. The surface morphology of MXene / ceramic composite nanofiltration membranes under different thermal crosslinking temperatures is characterized by scanning electron microscopy. When the temperature increases from 60°C to 400°C, the MXene wrinkle structure on the membrane surface becomes less and less, and the separation layer of the MXene membrane is tightly combined due to the decrease in interlayer spacing, which is attributed to the thermal crosslinking dehydration reaction between adjacent MXene layers.

[0046] (3) Inorganic salt separation nanofiltration application of MXene / ceramic composite nanofiltration membrane: The inorganic salt separation performance of MXene / ceramic composite nanofiltration membranes treated at different thermal crosslinking temperatures is tested to investigate the rejection rates of Na2SO4, MgSO4, NaCl, MgCl2 and VOSO4. The test conditions are set as follows: the inorganic salt concentration of the feed liquid is 0.01 mol / L, and the transmembrane pressure difference is 0.3 MPa.

[0047] Reference Figure 2 , Figure 2 In the above, Fig. a is the permeate rate and rejection rate of Na2SO4, Fig. b is the permeate rate and rejection rate of MgSO4, Fig. c is the permeate rate and rejection rate of NaCl, and Fig. d is the permeate rate and rejection rate of MgCl2; according to Figure 2It can be seen that as the thermal crosslinking temperature increases from 200℃ to 400℃, the permeability of the composite nanofiltration membrane gradually decreases, and the rejection rate correspondingly increases, and the maximum rejection rates are 75.9% (Na2SO4), 67.3% (MgSO4), 55.3% (NaCl) and 46.1% (MgCl2), respectively. The rejection rate of the composite nanofiltration membrane to inorganic salts follows the rule of R (Na2SO4) > R (MgSO4) > R (NaCl) > R (MgCl2), which is consistent with the Donnan effect equilibrium theory, indicating that the electrostatic repulsion plays a very important role in the separation of inorganic salts by the MXene / ceramic nanofiltration composite membrane.

[0048] Reference Figure 3 , Figure 3 In the above, the left graph is a result graph of the relationship between the permeability and the rejection rate of the MXene / ceramic composite nanofiltration membrane to VOSO4 at different thermal crosslinking temperatures; a larger size VOSO4 inorganic salt is selected to explore the separation mechanism of the composite nanofiltration membrane, and when the thermal crosslinking temperature increases from 200℃ to 400℃, the rejection rates of the composite nanofiltration membrane to the VOSO4 inorganic salt solution are 97.4%, 98.8% and 99.2%, respectively. After filtration, the VOSO4 solution changes from the original blue solution to a nearly colorless solution, and the permeate color of the membrane crosslinked at 400℃ is the lightest, almost colorless and transparent. The rejection rate of the composite nanofiltration membrane to the VOSO4 solution is higher than that of Na2SO4, MgSO4, NaCl and MgCl2, indicating that the steric hindrance effect also plays an important role in the separation of inorganic salts by the MXene / ceramic nanofiltration composite membrane.

[0049] Example 2 (1) Preparation of MXene-CNT composite membrane material: Put 7 mol / L hydrochloric acid in the polytetrafluoroethylene reactor liner, then put 1 g of lithium fluoride into the reactor liner to generate hydrofluoric acid for etching the MAX phase (400 mesh, Ti3AlC2); put 1.2 g of MAX phase into the generated hydrofluoric acid solution, heat in water bath, etch, then ultrasonic treatment to make it peel off, and get Ti3C2T x MXene small nanosheets. Then, a certain mass of functionalized CNT is dispersed in deionized water to prepare a CNT dispersion. Then, it is mixed with MXene small nanosheets according to a mass ratio of 1:4, stirred for 15 min, and ultrasonically treated in an ice bath environment for 30 min to prepare a uniform MXene-CNT dispersion, and the total loading amount is controlled to be 0.01 mg / cm 2 .

[0050] (2) Preparation of MXene-CNT / ceramic composite nanofiltration membrane by thermal crosslinking method: The MXene-CNT dispersion liquid was deposited into the inner surface of a single-tube ceramic support body by using nitrogen-assisted pressure filtration, and was subjected to thermal crosslinking treatment at different temperatures (room temperature, 80°C, 120°C, and 180°C) for 4 hours, to obtain PMCNM, MCNM-80, MCNM-120, and MCNM-180 composite membranes, respectively.

[0051] Reference Figure 4 , Figures a to d are scanning electron microscope images of the surface morphology of the PMCNM, MCNM-80, MCNM-120, and MCNM-180 composite membranes, respectively; Figures e to h are scanning electron microscope images of the cross-sectional morphology of the PMCNM, MCNM-80, MCNM-120, and MCNM-180 composite membranes, respectively; it can be seen from the surface morphology electron microscope images that most of the carbon nanotubes are uniformly embedded in the MXene nanosheet layers, and only a small number of carbon nanotubes are exposed on the surface of the MXene-CNT / ceramic composite nanofiltration membrane; the interlayer nanochannel of the MXene can be expanded by the intercalation of the carbon nanotubes, and a continuous maze-like three-dimensional mass transfer channel is formed by the assembly of the two, which can alleviate the phenomenon of reduced permeability caused by the serious accumulation between adjacent MXene nanosheets and the narrow interlayer spacing. It can be seen from the cross-sectional morphology electron microscope images that the membrane layer and the support body are tightly combined, and there is no obvious boundary between the two; and with the increase of the thermal crosslinking temperature, the thickness of the composite membrane decreases from ~187 nm to ~78 nm; the significant change in thickness can be attributed to the loss of free water and bound water between the layers, and the thermal crosslinking reaction between the MXene nanosheet and the surface groups of the CNT.

[0052] (3) Dye separation application of MXene-CNT / ceramic composite nanofiltration membrane: Different molecular weight organic dye molecules, Congo Red (CR, 696.7 Da), Rhodamine B (RhB, 479 Da), and Methyl Orange (MO, 327.3 Da) were selected as the substances to be intercepted, and the feed concentration of the organic dye molecules was 10 ppm; the permeability and interception performance of the MXene-CNT / ceramic composite nanofiltration membrane were tested at room temperature and under a transmembrane pressure difference of 0.1 MPa.

[0053] Reference Figure 5 , Figure a is the permeability of pure water, Figure b is the permeability and interception rate of CR, Figure c is the permeability and interception rate of RhB, and Figure d is the permeability and interception rate of MO; the composite nanofiltration membrane has a high pure water permeability, which is 126.2 L·m -2 ·h -1 ·bar -1 (PMCNM), 76.5 L·m -2 ·h -1 ·bar -1 (MCNM-80), 48.1 L·m-2 ·h -1 ·bar -1 (MCNM-120) and 24.8 L·m -2 ·h -1 ·bar -1 (MCNM-180), due to the effective mitigation of the stacking phenomenon of MXene films by CNT intercalation, the three-dimensional labyrinthine network structure assembled between functionalized carbon nanotubes and ultrathin two-dimensional MXene nanosheets promotes the penetration of aqueous solutions. By comparing the rejection rates of MCNMs for three different molecular weight organic dye molecules, it is found that the rejection rate of MCNMs for CR with larger molecular weight is the highest, while the rejection rate for MO with smaller molecular weight is the lowest. The results show that the rejection rate of MCNMs membrane gradually increases with the increase of dye molecular weight, which reflects the influence of steric hindrance effect on the separation process of MCNMs.

[0054] Example 3 (1) Ti3C2T x Preparation of MXene macro-nanosheet: 9 mol / L hydrochloric acid was placed in the polytetrafluoroethylene reaction kettle lining for standby, then 1 g of lithium fluoride was added to the reaction kettle lining to generate hydrofluoric acid for etching MAX phase (200 mesh, Ti3AlC2); 2 g of MAX phase was placed in the generated hydrofluoric acid solution, heated in a water bath, etched, and then subjected to shock treatment to make it peel off, obtaining Ti3C2T x MXene macro-nanosheet.

[0055] (2) Preparation of TiO2@MXene / ceramic composite nanofiltration membrane by in-situ thermal induction method: Ti3C2T x MXene macro-nanosheet (loading amount 0.015 mg / cm 2 ) was loaded onto the outer surface of the single-tube ceramic membrane support, and dried at 30℃ for 4 h, then the membrane was placed in a muffle furnace for in-situ thermal induction in air atmosphere, the thermal induction temperature was 600℃, the heating rate was 5℃ / min, and the holding time was 2 min, during which Ti3C2T x MXene surface will combine with oxygen atoms to form hydrophilic TiO2 particles, obtaining TiO2@MXene / ceramic composite nanofiltration membrane with 0D-2D structure.

[0056] Reference Figure 6 , after in-situ thermal induction, due to the partial Ti3C2T xThe color of the surface of the transformed TiO2 nanoparticles changes from dark green to white, and presents super-smooth metal luster. The structural characteristics of the membrane are as follows: 2D MXene is used as a two-dimensional platform for depositing 0D TiO2, after in-situ thermal induction, TiO2 and MXene are connected with each other to form a 0D-2D TiO2@MXene nanofiltration membrane with super-smoothness, super-hydrophilicity and high permeation flux, which is helpful for the rapid formation of a continuous and stable hydration layer on the membrane surface during the separation process, effectively preventing pollutants from aggregating on the membrane surface and improving the anti-fouling performance.

[0057] (3) Application of TiO2@MXene / ceramic composite nanofiltration membrane in dye desalination: A mixture of organic dye molecules Congo red and inorganic salt NaCl is selected as the separation material, and the permeation performance and rejection performance of the TiO2@MXene / ceramic composite nanofiltration membrane are tested at room temperature and under a transmembrane pressure difference of 0.1 MPa, wherein the feed concentration of Congo red is 10 ppm, and the feed concentration of NaCl is 0.01 mol / L -1 . The rejection rate of the composite nanofiltration membrane with a loading amount of 0.015 mg / cm 2 for Congo red is as high as 97.2%, and the rejection rate for NaCl is as low as 3.3%, basically realizing the separation of Congo red / NaCl.

[0058] (1) Preparation of Ti3C2T x MXene large nanosheet: 9 mol / L hydrochloric acid is placed in a polytetrafluoroethylene reaction kettle lining for standby, then 1 g of lithium fluoride is added to the reaction kettle lining to generate hydrofluoric acid for etching the MAX phase (200 mesh, Ti3AlC2); 2 g of the MAX phase is placed in the generated hydrofluoric acid solution, heated in a water bath, and subjected to oscillation treatment to make it peel off, thereby obtaining Ti3C2T x MXene large nanosheet with a horizontal size of 1000-5000 nm.

[0059] (2) Preparation of TiO2@MXene / ceramic composite nanofiltration membrane by in-situ thermal induction method: Ti3C2T x MXene large nanosheet (loading amount: 0.015 mg / cm 2 ) is loaded onto the outer surface of a single-tube ceramic membrane support by vacuum-assisted suction filtration, and is dried at 30℃ for 4 h, then the membrane is placed in a muffle furnace for in-situ thermal induction in an air atmosphere, the thermal induction temperature is 600℃, and the heating rate is 5℃ / min. In this process, the variable valence Ti on the surface of Ti3C2T x MXene will combine with oxygen atoms to form hydrophilic TiO2 particles, thereby obtaining a TiO2@MXene / ceramic composite nanofiltration membrane with 0D-2D structure.

[0060] Reference Figure 6 , after in-situ thermal induction, due to the partial Ti3C2T x conversion TiO2 nanoparticles, the film surface color changes from dark green to white, and presents super-smooth metal luster, and this film structure features: 2D MXene as a two-dimensional platform for depositing 0D TiO2, after in-situ thermal induction, TiO2 and MXene are connected to form a super-smooth, super-hydrophilic, high permeation flux 0D-2D TiO2@MXene nanofiltration membrane, which helps to form a continuous and stable hydration layer on the membrane surface during the separation process, effectively preventing pollutants from coalescing on the membrane surface, and improving the anti-fouling performance.

[0061] (3) Application of TiO2@MXene / ceramic composite nanofiltration membrane in dye desalination: The mixture of organic dye molecules Congo red and NaCl inorganic salt is selected as the separation material, and the permeation performance and retention performance of the TiO2@MXene / ceramic composite nanofiltration membrane are tested at room temperature and 0.1 MPa transmembrane pressure difference, wherein the feed concentration of Congo red is 10 ppm, and the feed concentration of NaCl is 0.01 mol L -1 . Among them, the composite nanofiltration membrane with a loading amount of 0.015 mg / cm 2 has a Congo red retention rate as high as 97.2%, and a NaCl retention rate as low as 3.3%, basically realizing the separation of Congo red / NaCl.

[0062] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

[0063] In summary, the technical scheme of the present application has the following beneficial technical effects: 1. The present application utilizes the excellent lateral size of MXene to modify the macropore defects of the ceramic support body, without the need for an additional transition layer, which not only greatly simplifies the preparation process flow and reduces the complexity of the production steps, but also significantly improves the overall production efficiency. Since the production and integration process of the transition layer is omitted, the method not only reduces the production cost, but also ensures the consistency and reliability of the composite nanofiltration membrane.

[0064] 2. The present application effectively adjusts the interlayer spacing through the thermal cross-linking dehydration reaction of the hydroxyl groups in MXene membrane materials, thereby precisely adjusting the spacing between MXene membranes. This regulation method provides a solid foundation for improving the separation precision of nanofiltration membranes. Specifically, by controlling the heat treatment conditions, the interlayer distance of MXene can be fine-tuned to better suit the filtration and separation needs of specific substances. This feature allows the prepared nanofiltration membranes to more accurately distinguish between molecules of different sizes or charges when faced with complex mixtures, thereby achieving high-efficiency separation effects.

[0065] 3. The present application generates TiO2 nanoparticles in situ during the heat-induced process by means of the variable titanium atoms of MXene membrane materials, constructing a super-smooth TiO2@MXene hydrophilic nanofiltration separation layer, which improves the hydrophilicity of the membrane surface, reduces the deposition of pollutants on the membrane surface, and enhances the anti-fouling performance of the membrane. In addition, the presence of TiO2 nanoparticles further optimizes the physical and chemical properties of the nanofiltration membrane, giving it stronger mechanical strength and higher chemical stability, ensuring that it maintains high-efficiency and stable separation performance during long-term operation.

Claims

1. A method for preparing a MXene-based / ceramic composite nanofiltration membrane, characterized in that: include: S1. Provide Ti3AlC2, mix it with hydrofluoric acid under heating conditions to cause etching reaction, peel it off, and obtain Ti3C2T x MXene nanosheets; S2. Ti3C2T x MXene nanosheets are deposited onto the surface of a ceramic membrane support, dried, and thermally cross-linked to obtain a MXene-based / ceramic composite nanofiltration membrane; Wherein, T is at least one of -F, -O and -OH, and x is 0 to 2.

2. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 1, wherein: Step S1 includes: LiF was dissolved in HCl solution to generate HF, and Ti3AlC2 precursor was added, heated in a water bath, and peeled off to obtain Ti3C2T x MXene nanosheets; The mass ratio of LiF to Ti3AlC2 is 1:(0.8-1.2), and the concentration of HCl is 3-9 mol / L.

3. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 1, wherein: Step S2 includes: The MXene nanosheets or a mixture thereof are loaded on the surface of a ceramic support by a vacuum or pressure-assisted filtration method, dried, and heat-treated to obtain a MXene-based / ceramic composite nanofiltration membrane.

4. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 3, wherein: The structure of the ceramic support is a sheet, a single tube, a hollow fiber or a multi-channel structure; and / or, The material of the ceramic support comprises at least one of Al2O3, ZrO2 and TiO2; and / or, The average pore size of the ceramic support is in the range of 20 to 5000 nm.

5. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 3, wherein: In step S2: The lateral size of the MXene nanosheets is 100 to 5000 nm, and the loading amount of the MXene nanosheets on the surface of the porcelain support is 0.01 to 0.1 mg / cm 2 .

6. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 3, wherein: In step S2: the drying temperature is 25 to 60° C. and the drying time is 2 to 12 h; and / or, The heat treatment temperature is 25-600°C, the heating rate is 0.5-10°C / min, and the holding time is 1 min-5 h.

7. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 1, wherein: Step S1 includes: S11. LiF was dissolved in HCl solution to generate HF, and Ti3AlC2 precursor was added. The mixture was heated in a water bath and peeled off to obtain Ti3C2T x MXene nanosheets; S12. Provide a CNT dispersion, and mix the Ti3C2T x Mixing the MXene nanosheets with the CNT dispersion and sonicating to obtain a MXene-CNT dispersion; Step S2 includes: The MXene-CNT dispersion is loaded on the surface of a ceramic support by vacuum or pressure-assisted filtration, dried, and heat-treated to obtain a MXene-based / ceramic composite nanofiltration membrane.

8. The method for preparing a MXene-based / ceramic composite nanofiltration membrane according to claim 7, wherein: In step S12, the Ti3C2T x The mass ratio of MXene nanosheets to the CNT dispersion is (3-5):

1.

9. A MXene-based / ceramic composite nanofiltration membrane, characterized in that: The invention relates to a MXene-based / ceramic composite nanofiltration membrane prepared by the method for preparing a MXene-based / ceramic composite nanofiltration membrane according to any one of claims 1 to 8.

10. Use of the MXene-based / ceramic composite nanofiltration membrane according to claim 9 in nanofiltration.

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