Ceramic membrane as well as preparation method and application thereof

Abstract

The invention relates to the technical field of inorganic functional ceramic membranes, in particular to a ceramic membrane and a preparation method and application thereof. According to the invention, Al2O3 with a specific crystal form is taken as a main raw material, and the ceramic membrane is prepared by an ultrasonic-atomization method with specific parameters, so that the problems of non-uniform separation layer structure and dispersed pore size in the traditional preparation process are successfully solved. According to the preparation method, slurry is efficiently atomized into micro-nano liquid drops by virtue of an ultrasonic-atomization technology, and the liquid drops are uniformly deposited on the surface of a ceramic base membrane by finely regulating and controlling the sizes and distribution of the liquid drops, so that a separation layer with a uniform structure is formed. The process not only obviously improves the structural uniformity and aperture concentration ratio of the ceramic membrane separation layer, but also can realize high separation performance under the thinner separation layer, and effectively improves the anti-pollution capacity of the membrane. Based on the advantages, the ceramic membrane has a wide application prospect in the field of water treatment with strict requirements on membrane separation efficiency and stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of inorganic functional ceramic membrane, in particular to a ceramic membrane and a preparation method and application thereof. BACKGROUND

[0002] Membrane filtration technology is widely used in drinking water treatment and wastewater advanced treatment due to its small footprint, easy operation and management, and good water quality, and has become an important technical means to improve water quality and ensure water supply safety. Compared with traditional organic membranes, ceramic membranes have uniform pore size distribution, high porosity, strong mechanical stability, and characteristics such as corrosion resistance, high temperature resistance, and oxidation resistance, and exhibit significant advantages in anti-membrane fouling.

[0003] Currently, most commercial porous ceramic membranes are of asymmetric structure, composed of a support body, an intermediate layer and a separation layer. Solid particle sintering method is the mainstream technology for industrial production of porous ceramic membranes, which can be used to produce microfiltration, ultrafiltration and nanofiltration products. Among them, coating the separation layer membrane material on the surface of the support body and sintering it into shape is the core link of the preparation of porous ceramic membranes, which directly affects the performance of the membrane. However, the existing industrial coating method has obvious defects: it relies on pressure or centrifugal force to disperse the slurry into droplets and coat it on the ceramic membrane substrate through a spray gun or a disc atomizer. Not only is the spray impact force large, which can easily cause raw material splashing and waste and air pollution, but more importantly, the uniformity of the atomized particles is poor and the spray flow is difficult to control precisely, which directly causes the pore size of the separation layer of the prepared ceramic membrane to be uneven, the membrane layer consistency to be poor, and cracks to be prone to occur, thereby seriously deteriorating the quality of the ceramic membrane and further reducing the core performance of the ceramic membrane such as filtration precision and separation efficiency.

[0004] Therefore, it is urgent to develop a method that can realize uniform slurry atomization and thus prepare a ceramic membrane with excellent performance. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the defects and deficiencies of the existing industrial coating method, such as uneven pore size of the separation layer of the prepared ceramic membrane, poor membrane layer consistency, and cracks prone to occur, which affect the separation performance of the ceramic membrane, and to provide a preparation method of a ceramic membrane.

[0006] Another object of the present application is to provide a ceramic membrane prepared by the above preparation method.

[0007] Still another object of the present application is to provide an application of the above ceramic membrane in the field of water treatment.

[0008] The above objects of the present application are achieved by the following technical solutions: The present application protects a preparation method of a ceramic membrane, comprising the following steps: S1. After mixing the raw materials, ball milling and degassing, a slurry is obtained; S2. The slurry obtained in step S1 is sprayed on the surface of the ceramic substrate film by an ultrasonic atomization method, dried and calcined to obtain a ceramic membrane; In step S1, the raw material comprises alpha-Al2O3, a binder, a dispersant and water; the solid content of the slurry is 5wt%-20wt%. In step S2, the sample flow rate of the spraying is 120-300 mL·h -1 , and the spraying speed is 10-25 mm·s -1 .

[0009] The present application uses a specific crystal form of Al2O3 as the main raw material, and prepares a ceramic membrane by an ultrasonic atomization method with specific parameters, which successfully solves the problems of uneven separation layer structure and pore size dispersion in the traditional preparation process. In the preparation method, by controlling the solid content in this range, the slurry can not only have good fluidity to meet the process requirements of spraying, coating and the like, but also can avoid the problems of low efficiency caused by too low solid content or particle agglomeration and uneven dispersion caused by too high solid content. By further using the ultrasonic atomization technology, the slurry is efficiently atomized into micro-nano droplets, and the droplet size and distribution are finely controlled, so that the droplets are uniformly deposited on the surface of the ceramic substrate film to form a separation layer with uniform structure. This process not only significantly improves the uniformity of the structure of the separation layer of the ceramic membrane and the concentration of the pore size, but also realizes high separation performance under a relatively thin separation layer, and effectively improves the anti-pollution ability of the membrane. Based on the above advantages, the ceramic membrane has broad application prospects in the water treatment field which has strict requirements on membrane separation efficiency and stability.

[0010] Further, in step S1, the particle size of the alpha-Al2O3 is 0.05-1 μm.

[0011] Preferably, in step S1, the particle size of the alpha-Al2O3 is 0.1-0.8 μm.

[0012] More preferably, in step S1, the particle size of the alpha-Al2O3 is 0.3-0.6 μm.

[0013] Further, in step S1, the binder comprises one or more of polyvinyl alcohol, polyethylene glycol and polypropylene pyrrolidone.

[0014] Further, in step S1, the addition amount of the binder is 0.1wt%-0.5wt% based on the mass percentage of alpha-Al2O3.

[0015] Preferably, in step S1, the addition amount of the binder is 0.15wt%-0.35wt% based on the mass percentage of alpha-Al2O3.

[0016] More preferably, in step S1, the binder is added in an amount of 0.18wt%~0.30wt% based on the mass percentage of α-Al2O3.

[0017] Further, in step S1, the dispersant includes one or more of sodium carboxymethyl cellulose, sodium polyacrylate, and polyacrylic acid.

[0018] Further, in step S1, the dispersant is added in an amount of 0.01wt%~0.50wt% based on the mass percentage of α-Al2O3.

[0019] Preferably, in step S1, the dispersant is added in an amount of 0.02wt%~0.30wt% based on the mass percentage of α-Al2O3.

[0020] More preferably, in step S1, the dispersant is added in an amount of 0.03wt%~0.15wt% based on the mass percentage of α-Al2O3.

[0021] Further, in step S1, the mass-to-volume ratio of the α-Al2O3 and water is 1: (8~12) g / mL.

[0022] Further, in step S1, the ball milling time is 2~48 h.

[0023] Preferably, in step S1, the ball milling time is 3~20 h.

[0024] More preferably, in step S1, the ball milling time is 4~10 h.

[0025] Preferably, in step S1, the ball-to-material ratio of the ball milling is 1: (5~25).

[0026] More preferably, in step S1, the ball-to-material ratio of the ball milling is 1: (8~15).

[0027] Further, in step S1, the degassing time is 0.5~6 h.

[0028] Preferably, in step S1, the degassing pressure is 0.05~1.0 MPa.

[0029] Further, in step S1, the solid content of the slurry is 8wt%-15wt%. The solid content is the proportion of solid substances in the total mass of the slurry, and its actual calculation method is: the mass of all solid raw materials divided by the total mass of all raw materials in the slurry, and the resulting ratio is the solid content. Taking Example 1 as an example, the specific calculation of the solid content of the slurry is: m (α-Al2O3+ polyvinyl alcohol+ carboxymethyl cellulose) / m (α-Al2O3+ polyvinyl alcohol+ carboxymethyl cellulose+ water) = 20.048 g / 220.048 g ≈ 9.1wt%.

[0030] Further, in step S2, the resonance frequency of the spraying is 20-60 kHz.

[0031] Preferably, in step S2, the sample flow rate of the spraying is 130-250 mL·h -1 , and the spraying speed is 11-20 mm·s -1 .

[0032] More preferably, in step S2, the sample flow rate of the spraying is 150-200 mL·h -1 , and the spraying speed is 12-18 mm·s -1 .

[0033] Further, as a preferred way, in step S2, the instrument used in the ultrasonic-atomization method is an ultrasonic-atomization combined instrument.

[0034] Further, in step S2, the ceramic base film can be purchased or self-made.

[0035] Further, the self-made ceramic base film can be prepared according to Chinese Patent CN118047595A.

[0036] Preferably, in step S2, the average pore size of the ceramic base film is 0.4-1 μm, and the porosity is 40-60%.

[0037] Further, the porosity is the proportion of the total volume of all pores in the ceramic film to the total volume of the film, and its determination method is as follows: first, when the dry ceramic film is completely infiltrated and saturated by the liquid, the pores will be filled with liquid, and by measuring the weight difference between the dry film and the saturated film, combined with the density of the liquid, the pore volume can be calculated; second, the geometric dimensions (such as length, width, and thickness) of the film are measured to calculate the skeleton solid volume, and then the above measured pore volume is added to obtain the total volume of the film; finally, the porosity is calculated by the formula "pore total volume divided by film total volume".

[0038] More preferably, in step S2, the average pore size of the ceramic base film is 0.5-0.7 μm, and the porosity is 40-60%.

[0039] Preferably, in step S2, the drying is baking.

[0040] Further, in step S2, the drying temperature is 60-120 ℃.

[0041] Preferably, in step S2, the drying time is 0.5-2 h.

[0042] Further, in step S2, the calcination temperature is 1100-1500 ℃.

[0043] Preferably, in step S2, the calcination temperature is 1100-1500 ℃.

[0044] Preferably, in step S2, the calcination time is 0.5-5 h.

[0045] The application protects the ceramic membrane prepared by the above preparation method.

[0046] Further, the average pore size of the ceramic membrane is 0.10-0.25 μm, and the membrane layer thickness is 20-40 μm.

[0047] The application protects the application of the above ceramic membrane in the field of water treatment.

[0048] Further, the field of water treatment includes one or more of drinking water preparation, municipal sewage treatment, industrial wastewater treatment, and seawater desalination pretreatment.

[0049] Compared with the prior art, the application has the following beneficial effects: The application uses a specific crystal form of Al2O3 as the main raw material, and prepares a ceramic membrane by an ultrasonic-atomization method with specific parameters, successfully solving the problems of uneven separation layer structure and pore size dispersion in traditional preparation processes. The preparation method uses ultrasonic-atomization technology to efficiently atomize the slurry into micro-nano droplets, finely controls the droplet size and distribution, makes the droplets uniformly deposit on the surface of the ceramic substrate membrane, and forms a separation layer with uniform structure. This process not only significantly improves the structure uniformity and pore size concentration of the ceramic membrane separation layer, but also realizes high separation performance under a relatively thin separation layer, and effectively improves the anti-pollution ability of the membrane. Based on the above advantages, the ceramic membrane has broad application prospects in the field of water treatment which has strict requirements on membrane separation efficiency and stability. BRIEF DESCRIPTION OF DRAWINGS

[0050] Figure 1 The SEM image of the ceramic membrane in Example 1.

[0051] Figure 2 The SEM image of the ceramic membrane in Example 1.

[0052] Figure 3 SEM image of the ceramic membrane in Comparative Example 1; Figure 3 (c) is Figure 3 (a) is a partial enlarged view of

[0053] Figure 4 Pore size distribution graph of the ceramic membrane in Example 1, Comparative Example 1. DETAILED DESCRIPTION

[0054] The present application will be further described by the following description of the drawings and specific examples, but the examples do not limit the present application in any form. Unless otherwise specified, the reagents, methods and equipment used in the present application are conventional reagents, methods and equipment in the technical field.

[0055] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0056] Figure 1 (a) represents Figure 1 (a) in FIG. 1, Figure 1 (b) represents Figure 1 (b) in FIG. 2, and the other figures are sequentially similar.

[0057] Example 1 Preparation of a ceramic membrane S1. α-Al2O3, polyvinyl alcohol, sodium carboxymethyl cellulose and water were mixed in a certain proportion, wherein the input amount of α-Al2O3 (particle size 0.5 μm) was 20 g, the mass of polyvinyl alcohol was 0.2wt% of α-Al2O3, the mass of sodium carboxymethyl cellulose was 0.04wt% of α-Al2O3, and 200 mL of water (density 1 g / cm 3 ) under standard conditions) was mixed and stirred for 6 h. The stirred raw materials were ball milled under the condition of a ball-to-material ratio of 1:10 for 4 h to obtain a mixture, and then the mixture was subjected to a degassing treatment for 30 min under the condition of 0.1 MPa to obtain a slurry with a solid content of 9.1wt%; S2. The slurry obtained in step S1 was atomized into micro-nano droplets by an ultrasonic-atomization combined instrument, and sprayed onto the surface of a ceramic base membrane (average pore size 0.7 μm, porosity 48%). The resonance frequency of the spraying was 50 kHz, the sample flow rate of the spraying was 150 mL·h -1 , and the spraying speed was 12 mm·s -1 After the ceramic base membrane surface after spraying was dried at 95 ℃ for 10 min, it was heated to 1280 ℃ at a rate of 5 ℃ / min and calcined for 2 h to obtain a ceramic membrane with an average pore size of 0.162 μm and a membrane separation layer of 31 μm.

[0058] Example 2 Preparation of a ceramic membrane The difference from Example 1 is that in step S1, the particle size of α-Al2O3 is replaced by 0.1 μm; in step S2, a ceramic membrane with an average pore size of 0.150 μm and a membrane separation layer of 30 μm is obtained.

[0059] The other steps and conditions are consistent with Example 1.

[0060] Example 3 Preparation of a ceramic membrane The difference from Example 1 is that in step S1, the sample flow rate is replaced by 150 mL·h -1 modified to 200 mL·h -1 , a ceramic membrane with an average pore size of 0.204 μm and a membrane separation layer of 35 μm is obtained.

[0061] The other steps and conditions are consistent with Example 1.

[0062] Example 4 Preparation of a ceramic membrane The difference from Example 1 is that in step S2, the spraying speed is replaced by 12 mm·s -1 to 18 mm·s -1 , a ceramic membrane with an average pore size of 0.218 μm and a membrane separation layer of 26 μm is obtained.

[0063] The other steps and conditions are consistent with Example 1.

[0064] Comparative Example 1 Preparation of a ceramic membrane The difference from Example 1 is that in step S2, the ultrasonic-atomization combination instrument is replaced by a pneumatic high-atomization spray gun, which comprises the following steps: S1. α-Al2O3, polyvinyl alcohol, sodium carboxymethyl cellulose and water are mixed in a certain proportion, wherein the input amount of α-Al2O3 (particle size 0.5 μm) is 20 g, the mass of polyvinyl alcohol is 0.2wt% of α-Al2O3, the mass of sodium carboxymethyl cellulose is 0.04wt% of α-Al2O3, 200 mL of water is mixed and stirred for 6 h, the stirred raw materials are ball milled under the condition of ball to material ratio of 1:10 for 4 h, then the mixture is degassed under the condition of 0.1 MPa for 30 min, and a slurry with a solid content of 9.8wt% is obtained; S2. The slurry obtained in step S1 is sprayed on the surface of the ceramic base membrane (average pore size 0.7 μm, porosity 48%) by a pneumatic high-atomization spray gun, the slurry flow rate is 150 mL·min -1 , the spraying speed is 12 mm·s -1After the ceramic membrane surface after spraying is dried at 95 ℃ for 10 min, it is heated to 1280 ℃ at a rate of 5 ℃ / min, and calcined for 2 h, to obtain a ceramic membrane with an average pore size of 0.236 μm and a membrane separation layer of 10-30 μm.

[0065] Preparation of a ceramic membrane The difference from Example 1 is that in step S2, the sample flow rate is changed from 150 mL·h -1 to 100 mL·h -1 , to obtain a ceramic membrane with an average pore size of 0.463 μm and a membrane separation layer of about 15 μm.

[0066] The other steps and conditions are the same as those in Example 1.

[0067] Preparation of a ceramic membrane The difference from Example 1 is that in step S2, the spraying speed is changed from 12 mm·s -1 to 6 mm·s -1 , to obtain a ceramic membrane with an average pore size of 0.389 μm and a membrane separation layer of 20-40 μm in thickness.

[0068] The other steps and conditions are the same as those in Example 1.

[0069] Preparation of a ceramic membrane slurry The difference from Example 1 is that in step S1, the α-Al2O3 is replaced with an equal amount of γ-Al2O3.

[0070] The other steps and conditions are the same as those in Example 1.

[0071] Experimental results: The slurry prepared using γ-Al2O3 is prone to solid-liquid separation, and cannot form a uniform and stable slurry system.

[0072] Physical property characterization of ceramic membranes 1.SEM characterization The ceramic membranes in Examples 1-2 and Comparative Example 1 are characterized by scanning electron microscopy (SEM, TM4000 II, Japan Hitachi; SIGMA 300, Germany ZEISS), and the results are shown in Figures 1-3 Figures 1(a)-(b) and 2(a)-(b): The ceramic membranes prepared by the ultrasonic-atomization spraying method in Example 1 Figure 1 (a)-(b) and Example 2 Figure 2 (a)-(b) have smooth separation membrane layer surfaces, no obvious membrane layer stacking, caking, cracking, etc., and the pore structure is relatively loose, and the membrane layer thickness is uniform; the ceramic membrane prepared by the pneumatic high-atomization spraying gun in Comparative Example 1 has a surface with uneven membrane layer uniformity, and there are pits and valleysFigure 3 (a)~(b)), and obvious cracks appeared on the membrane surface ( Figure 3 (c)). Therefore, the present invention improves the pore size uniformity and membrane layer consistency of the ceramic membrane by precisely controlling the atomized particle size and distribution of the ceramic membrane slurry, thereby significantly improving the quality of the ceramic membrane.

[0073] The morphological characteristics of the catalytic ceramic membranes obtained in Examples 3 and 4 are basically the same as those in Example 1 and will not be repeated here.

[0074] 2. Pore size distribution The average pore size of the ceramic membranes in Example 1 and Comparative Example 1 was characterized by bubble pressure method. The results are as follows: Figure 4 As shown, the pore size of the ceramic membrane of Example 1 is uniformly distributed within the range of 0.130-0.170 μm, while the pore size of the ceramic membrane of Comparative Example 1 is dispersed into two intervals, 0.183-0.259 μm and 0.330-0.425 μm, respectively, indicating a low pore size concentration. Therefore, the preparation method of the present invention can construct a small-pore separation layer (pore size range of 0.1-0.25 μm) on the surface of the ceramic base membrane with concentrated and uniform pore size, thereby improving the pure water flux of the membrane, reducing the turbidity of the effluent, and slowing the rate of increase of the transmembrane pressure difference.

[0075] The catalytic ceramic membranes obtained in Examples 2 to 4 have uniform pore size distribution and good concentration, which will not be described in detail here.

[0076] Experimental Example 2 Characterization of physical and chemical properties of ceramic membranes 1. Experimental Methods Pore ​​size characterization: The average pore size of the ceramic membranes in Examples 1 to 5 and Comparative Examples 1 to 3 was analyzed using a bubble pressure pore size analyzer (BSD-PB, Best Instruments, China).

[0077] Pure water flux: All ceramic membrane components were immersed in deionized water and cleaned under 20 kHz ultrasonic waves for 5 min to remove all loose impurity particles on the surface of the ceramic membrane during the preparation process. They were immersed for 30 min before operation to reduce bubbles between the pores of the ceramic membrane and maintain a stable flux. They were then filtered with deionized water. After the effluent was stable, the pure water flux was measured according to formula (1). J=V / A*t*P(1) Where J is the pure water flux of the ceramic membrane (L / m -2 h -1 bar -1 ); V is the water output (L); A is the effective membrane surface area (m 2 ), t is the filtration time (h), and P is the transmembrane pressure (bar).

[0078] Water turbidity and trans-membrane pressure rise rate test: Based on the submerged constant flux water production mode and parallel experimental design: 3 L square water tank as membrane filtration reactor, reservoir raw water after coagulation sedimentation treatment as influent (turbidity about 3 NTU); through high water tank water supply and by the floating ball valve to maintain constant liquid level. Select the same effective area of the membrane assembly of the examples and the comparative examples, vertically immersed in the same reactor, through the parallel operation of the independent peristaltic pump (100 LMH•bar -1 flux water production, backwash for 1 minute after 60 minutes of water production), directly extract the produced water to determine the water turbidity; at the same time, install a vacuum pressure gauge between the membrane assembly and the peristaltic pump to monitor the trans-membrane pressure (TMP) for calculating the trans-membrane pressure rise rate. The experiment continues until the TMP rises to 35 kPa, then immerse in sodium hypochlorite solution to remove the irreversible pollution on the membrane surface, and then the next round of test can be carried out in circulation.

[0079] 2. Experimental results Table 1 Statistical table of physical and chemical properties of ceramic membranes

[0080] According to the specification of GB / T 39717-2020 "Ceramic Membrane Plate for Water Treatment", the average pore size of M0.1 type ceramic membrane needs to be controlled in 0.13~0.17 μm, and the pure water flux ≥0.5 m 3 ·h (i.e. 1250 LMH•bar 2 ·h (i.e. 1250 LMH•bar -1 ); the average pore size of M0.2 type ceramic membrane is 0.21~0.29 μm, and the pure water flux ≥1 m 3 ·h (i.e. 2500 LMH•bar 2 ·h (i.e. 2500 LMH•bar -1 ); the average pore size of M0.3 type ceramic membrane is 0.45~0.55 μm, and the pure water flux ≥1.8 m 3 ·h (i.e. 4500 LMH•bar 2 ·h (i.e. 4500 LMH•bar -1 ). From the data in Table 1, the catalytic ceramic membranes in Examples 1~4 improve the uniformity of the pore size and the consistency of the membrane layer by precisely controlling the particle size and distribution of the ceramic membrane slurry, thereby improving the anti-pollution ability of the ceramic membrane. Specifically: the average pore size is 0.150~0.218 μm, which covers the fine filtration requirements of M0.1 type and connects the high flux characteristics of M0.2 type, and the adaptation scene is more extensive; the pure water flux is 1967~2674 LMH•bar -1The ceramic membranes of Examples 1-2 meet the basic requirements of the M0.1 ceramic membrane standard, the ceramic membranes of Examples 3-4 meet the basic requirements of the M0.2 ceramic membrane standard, and both types of membranes exhibit significant advantages in water efficiency; the effluent turbidity is stable in the range of 0.087-0.093 NTU, which is lower than the limit value (0.1 NTU) of the conventional water quality standard, reflecting the excellent water purification effect of the ceramic membrane; the transmembrane pressure difference rising rate is stable in the range of 3.05-3.84 kPa·d -1 The low growth rate represents that the membrane has strong anti-pollution ability, which provides reliable guarantee for long-term stable operation of the membrane; and the high growth rate represents that the pollution accumulation rate on the surface of the membrane is too fast, which will significantly shorten the service life of the ceramic membrane. These performance data fully prove that the product of the application not only meets the industry standard, but also achieves breakthrough in key indicators, and has significant technical advantages.

[0081] Compared with Example 1, Comparative Example 1 uses a pneumatic high-atomization spray gun, so that the atomization particle uniformity is poor and the spray flow is difficult to fine control, which directly leads to uneven pore size of the separation layer of the prepared ceramic membrane, poor membrane layer consistency, and even cracks on the membrane surface, greatly reducing the filtration precision and separation efficiency of the ceramic membrane, and further causing the transmembrane pressure difference to increase and the pollution accumulation rate to accelerate; Comparative Example 2 reduces the sample flow of ultrasonic atomization, resulting in insufficient slurry supply during the formation of the membrane layer, and finally the membrane layer is thin and unevenly distributed. This structural defect directly causes the average pore size to increase to 0.463 μm, not only the membrane pore size is too large, but also the pure water flux does not meet the standard requirements of the M0.3 ceramic membrane, and at the same time, the transmembrane pressure difference rising rate is accelerated, which will cause the membrane surface pollution accumulation rate to accelerate; Comparative Example 3 reduces the ultrasonic atomization spraying speed, and when the working speed is too slow, the amount of slurry sprayed onto the surface of the base membrane is too much, causing the water penetration and evaporation speed to be unbalanced, which destroys the uniform distribution of the slurry on the surface of the base membrane, and further causes the slurry to accumulate and peel off. This defect finally manifests as an average pore size that is too large, a pure water flux that does not meet the standard requirements of the M0.3 ceramic membrane, and also an accelerated transmembrane pressure difference rising rate, which means that the pollution accumulation rate will also accelerate.

[0082] The above examples are preferred embodiments of the application, but the embodiments of the application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the application should be equivalent replacement methods and are included in the protection scope of the application.

Claims

1. A method for preparing a ceramic membrane, characterized in that: The following steps are involved: S1. After mixing the raw materials, ball milling and degassing to obtain a slurry; S2. The slurry obtained in step S1 is sprayed on the surface of the ceramic base membrane by ultrasonic-atomization method, dried and calcined to obtain a ceramic membrane; Wherein, in step S1, the raw materials include α-Al2O3, a binder, a dispersant, and water; the solid content of the slurry is 5wt%~20wt%; In step S2, the injection flow rate of the spraying is 120~300 mL·h -1 The spraying speed is 10~25 mm·s -1 .

2. The preparation method according to claim 1, characterized in that In step S1, the particle size of the α-Al2O3 is 0.05~1μm.

3. The preparation method according to claim 1, characterized in that In step S2, the average pore size of the ceramic base membrane is 0.4-1 μm, and the porosity is 40-60%.

4. The preparation method according to claim 1, characterized in that In step S1, the amount of the binder added is 0.1 wt% to 0.5 wt% based on the mass percentage of α-Al2O3.

5. The preparation method according to claim 1, characterized in that: In step S1, the amount of the dispersant added is 0.01 wt% to 0.50 wt% based on the mass percentage of α-Al2O3.

6. The preparation method according to claim 1, characterized in that: In step S2, the calcination temperature is 1100-1500°C.

7. The preparation method according to claim 1, characterized in that: In step S2, the resonant frequency of the spraying is 20-60 kHz.

8. A ceramic membrane prepared by the preparation method according to any one of claims 1 to 7.

9. The ceramic membrane according to claim 8, characterized in that: The average pore size of the ceramic membrane is 0.10-0.25 μm, and the membrane layer thickness is 20-40 μm.

10. Use of the ceramic membrane according to claim 8 or 9 in the field of water treatment.

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