A method for preparing a ceramic disc membrane

Abstract

The application provides a preparation method of a disc type ceramic membrane, comprising the following steps: mixing first alumina powder, second alumina powder, a pore forming agent, a binder and a sintering aid, and performing first ball milling to obtain a first slurry; performing spray granulation on the slurry to obtain granulation powder, and performing first sintering on the green body obtained by dry pressing the granulation powder to obtain a disc type ceramic membrane support body; mixing third alumina powder, copper oxide powder, lanthanum oxide powder, a binder, a dispersing agent and a solvent, and performing second ball milling to obtain a second slurry; uniformly coating the second slurry on the disc type ceramic membrane support body, and performing second sintering to load an alumina membrane on the disc type ceramic membrane support body to obtain the disc type ceramic membrane.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of ceramic filter, and particularly relates to a preparation method of a disc type ceramic membrane. BACKGROUND

[0002] Membrane separation technology is easy to be modularized, and easy to be updated, which can save cost while improving quality and efficiency. At present, membrane separation technology has been widely applied in food industry, biological engineering, environmental engineering, chemical industry, petroleum and chemical industry and metallurgical industry.

[0003] Ceramic membranes with inherent hydrophilicity and excellent chemical, mechanical and thermal stability for membrane separation technology are concerned. Specifically, the hydrophilicity of ceramic membranes makes them have high flux and antifouling properties in the separation and filtration process of water-based liquid systems. In addition, the chemical stability of ceramic membranes enables the ceramic membranes to be subjected to efficient biological / chemical treatment. The excellent mechanical stability of ceramic membranes enables them to work stably when treating sewage. Moreover, due to the mechanical stability, the contaminated ceramic membranes can be cleaned by using backwashing technology. This makes the ceramic membrane treatment have a longer service life in water and wastewater treatment.

[0004] However, there are still some problems in the ceramic membrane separation process, such as concentration polarization and membrane fouling. Due to concentration polarization and membrane fouling, the permeation flux of the membrane in the membrane filtration process will be reduced. This not only reduces the production efficiency, but also increases the energy consumption. Therefore, the decrease of flux greatly limits the application and development of membrane separation.

[0005] Disc type ceramic membrane is a new ceramic membrane configuration, which has a disc-shaped external shape, a spiral-shaped permeation channel inside, and a separation layer on the outer surface of the disc type ceramic membrane. The permeate first enters the permeation channel inside the disc type ceramic membrane from the surface of the disc type ceramic membrane, and then is collected and flows out through the hollow central shaft. The disc type ceramic membrane sheet rotates with the high-precision shaft driven by the motor, generates high fluid velocity on the membrane surface, and thus generates strong shear effect, forming dynamic filtration. This can greatly reduce membrane fouling. However, the disc type ceramic membrane is subjected to the scouring of particles in the filtration liquid for a long time during dynamic filtration. Therefore, the disc type ceramic membrane will be eroded and worn. This greatly reduces the service life of the membrane sheet, and the membrane sheet needs to be replaced regularly to achieve accurate filtration, which greatly increases the operation cost of membrane separation and is not conducive to its industrial application.

[0006] In summary, there is an urgent need for a ceramic material with high wear resistance to solve the above problems. SUMMARY

[0007] The purpose of the present application is to provide a preparation method of disc type ceramic membrane with high mechanical strength, wear resistance and large permeation flux.

[0008] The application is realized by the following technical scheme:

[0009] A preparation method of a disc type ceramic membrane, comprising the following steps:

[0010] Mixing the first alumina powder, the second alumina powder, the pore forming agent, the binder and the sintering aid and performing first ball milling to obtain a first slurry;

[0011] Spray granulating the slurry to obtain a granulated powder, forming a green body and then performing first sintering to obtain the disc type ceramic membrane support;

[0012] Mixing the third alumina powder, the copper oxide powder, the lanthanum oxide powder, the binder, the dispersing agent and the solvent, and then performing second ball milling to obtain a second slurry;

[0013] Uniformly coating the second slurry on the disc type ceramic membrane support, and then performing second sintering to load the alumina membrane on the disc type ceramic membrane support to obtain the disc type ceramic membrane;

[0014] In the alumina membrane, part of the third alumina powder, the copper oxide powder and the lanthanum oxide powder form sheet-shaped LaAl 11 O 18 during sintering; the sheet-shaped LaAl 11 O 18 is connected with adjacent sheet-shaped LaAl 11 O 18 at a certain angle, so that the sheet-shaped LaAl 11 O 18 forms a three-dimensional interlocking structure with the alumina particles in the alumina membrane.

[0015] The average particle size of the first alumina powder is 50 μm;

[0016] The average particle size of the second alumina powder is 5 μm;

[0017] The average particle size of the third alumina powder is 600 nm;

[0018] The pore forming agent comprises corn starch;

[0019] The binder comprises PEG or PVA;

[0020] The sintering aid comprises 30 wt% of silicon dioxide, 30 wt% of magnesium oxide and 40 wt% of calcium oxide.

[0021] The mass ratio of the first alumina powder, the second alumina powder, the pore forming agent, the binder and the sintering aid is 94:4:1:1.

[0022] The feeding speed of the spray granulation is 8 Kg / h;

[0023] The inlet temperature of the spray granulation is 340℃;

[0024] The outlet temperature of the spray granulation is 140℃;

[0025] The spray pressure of the spray granulation is 0.2MPa.

[0026] The temperature of the first sintering is 1380-1400℃;

[0027] The holding time of the first sintering is 2-5h.

[0028] The first sintering comprises the steps of: heating from room temperature to 300℃ at a heating rate of 2-5℃ / min, holding for 1-3h; heating from 300℃ to 1300℃ at a heating rate of 4-10℃ / min; heating from 1300℃ to 1400℃ at a heating rate of 1-3℃ / min, holding for 2-5h.

[0029] The mass percentage of the third alumina powder, the copper oxide-lanthanum oxide composite powder, the binder, the dispersant and the solvent is (30wt%-10wt%) :(1wt%-3wt%) :(5wt%-10wt%) :(0.5wt%-5wt%) :(50wt%-80wt%) ; the weight ratio of copper oxide and lanthanum oxide in the copper oxide-lanthanum oxide composite powder is 3-7.

[0030] The temperature of the second sintering is 1250-1300℃;

[0031] The holding time of the second sintering is 2-5h.

[0032] The second sintering comprises the steps of: heating from room temperature to 300℃ at a heating rate of 2-5℃ / min, holding for 1-3h; heating from 300℃ to 1200℃ at a heating rate of 4-10℃ / min; heating from 1200℃ to 1300℃ at a heating rate of 1-3℃ / min, holding for 2-5h.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] 1. The main raw material component of the preparation method of the disc type ceramic membrane provided by the present application is alumina powder, which is abundant in material, has a wide available purity range and is affordable, so that the preparation of the disc type ceramic membrane has a lower production cost.

[0035] 2. The preparation method of the disc type ceramic membrane provided by the application adopts the very regular spherical particles obtained by spray granulation as the aggregate of the support, and the particle size distribution is relatively narrow, the spherical particles are better stacked, a more uniform microstructure is obtained, the strength of the disc type ceramic membrane support is improved, and the disc type ceramic membrane is applicable to more application environments. Meanwhile, a more developed three-dimensional pore structure is formed, the overall filtration flux of the disc type ceramic membrane is improved, and the filtration efficiency is improved.

[0036] 3. The preparation method of the disc type ceramic membrane provided by the application can process the support into various simple shapes, the manufacturing process is simple, and the yield is high.

[0037] 4. The membrane layer of the disc type ceramic membrane provided by the application is prepared by taking copper oxide and lanthanum oxide as sintering aids and taking aluminum oxide as a matrix, the incorporation of the lanthanum oxide in the membrane layer generates sheet-shaped LaAl 11 O 18 The skeleton structure of the membrane layer is enhanced, and the porosity of the membrane layer is improved, and at the same time, the copper oxide as the sintering aid is incorporated to play a positive densification effect, so that the connection between the particles and the sheet-shaped LaAl 11 O 18 in the membrane layer is more compact to form a three-dimensional interlocking structure, the skeleton structure of the membrane layer is further enhanced, and finally the membrane layer obtains a good balance between mechanical strength and porosity, thereby having the advantages of high mechanical strength, wear resistance, and large permeation flux.

[0038] 5. The sintering process in the preparation method of the disc type ceramic membrane provided by the application is sintered at 1300 DEG C in an air atmosphere. Therefore, the method has the advantages of low sintering temperature, low production energy consumption, low equipment requirement, and low manufacturing cost.

[0039] 6. The ceramic membrane prepared by the preparation method of the disc type ceramic membrane provided by the application has a wide application range and can be used in special separation in chemical industry, biological fermentation, papermaking, food and beverage, mineral processing and other industries, and can also be used in tap water purification, sewage upgrading and reconstruction, wastewater treatment and recovery of useful substances, and water reuse. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 A disc type ceramic membrane dynamic filtration device and its working principle schematic diagram are shown;

[0041] Figure 2 A spiral-shaped permeation channel inside a disc type ceramic membrane and an external disc and plate type configuration are shown;

[0042] Figure 3 A SEM photo of the surface of the membrane layer of the disc type ceramic membrane prepared in Example 1 is shown;

[0043] Figure 4 A SEM photo of the surface of the membrane layer of the disc type ceramic membrane prepared in Example 1 is shown;

[0044] Figure 5 SEM photos of the surface of the disc ceramic membrane layer prepared in Example 1 are shown;

[0045] Figure 6 Energy spectrum of the surface of the disc ceramic membrane layer prepared in Example 1 is shown;

[0046] Figure 7 SEM photos of the disc ceramic membrane prepared in Example 1 are shown. 11 O 18 Schematic diagram of the three-dimensional interlocking structure between the alumina grains and the plate-like LaAl

[0047] Figure 8 XRD diagram of the disc ceramic membrane layer prepared in Example 1 is shown. DETAILED DESCRIPTION

[0048] The present application is further illustrated below with examples, but is not any limitation to the scope of the present application.

[0049] A preparation method of a disc ceramic membrane comprises the following steps:

[0050] The first alumina powder, the second alumina powder, the pore-forming agent, the binder and the sintering aid are mixed and subjected to first ball milling to obtain a first slurry; the slurry is subjected to spray granulation to form a green body and then subjected to first sintering to obtain the disc ceramic membrane support; the third alumina powder, the copper oxide powder, the lanthanum oxide powder, the binder, the dispersing agent and the solvent are mixed and then subjected to second ball milling to obtain a second slurry; the second slurry is uniformly coated on the disc ceramic membrane support and then subjected to second sintering, so that the alumina membrane is loaded on the disc ceramic membrane support to obtain the disc ceramic membrane; in the above preparation process, during sintering of the ceramic membrane, part of the third alumina powder, the copper oxide powder and the lanthanum oxide powder form the plate-like LaAl 11 O 18 ; the plate-like LaAl 11 O 18 is connected with the adjacent plate-like LaAl 11 O 18 at a certain angle to form a three-dimensional interlocking structure with the alumina particles in the alumina membrane. 11 O 18

[0051] In the preparation process of the ceramic membrane, only the copper oxide is added, so that the alumina matrix of the ceramic membrane forms a liquid phase during sintering, improves the sintering activity of the alumina particles and promotes the close connection between the particles in the membrane layer. However, the rearrangement and dissolution of the particles will have a positive densification effect, and the porosity of the membrane layer will sharply decrease. The addition of the lanthanum oxide alone to the alumina membrane layer forms the plate-like LaAl​11 O 18 The pore structure of the membrane layer can be improved and the porosity can be increased, but the neck connection between the grains is weak. Therefore, after the copper oxide powder and lanthanum oxide powder are co-doped into the aluminum oxide powder and sintered, the porosity can be increased while the connection between the granular and sheet-shaped LaAl 11 O 18 is tighter, the skeleton structure of the membrane layer is enhanced, thereby obtaining a ceramic membrane disc with strong wear resistance and large permeation flux. Moreover, during the sintering process of the ceramic membrane, due to the presence of copper oxide, part of the liquid phase is generated in the contact part of the ceramic support and the ceramic membrane. Therefore, the binding force between the ceramic membrane and the ceramic support after sintering is very strong, thereby effectively preventing the ceramic membrane from falling off during use and prolonging the service life of the ceramic membrane.

[0052] Preferably, the average particle size of the first aluminum oxide powder is 50 μm. Those skilled in the art can understand that the average particle size of the first aluminum oxide powder is about 50 μm, and the present application can also be achieved.

[0053] Preferably, the average particle size of the second aluminum oxide powder is 5 μm; those skilled in the art can understand that the average particle size of the second aluminum oxide powder is about 5 μm, and the present application can also be achieved.

[0054] Preferably, the average particle size of the third aluminum oxide powder is 600 nm; those skilled in the art can understand that the average particle size of the third aluminum oxide powder is about 600 nm, and the present application can also be achieved.

[0055] Preferably, the pore-forming agent can be corn starch;

[0056] Preferably, the binder includes PEG or PVA; other types of binders can also be selected.

[0057] Preferably, the sintering aid includes silicon dioxide, magnesium oxide and calcium oxide. Optionally, other types of sintering aids can also be selected.

[0058] Preferably, the mass ratio of the first aluminum oxide powder, the second aluminum oxide powder, the pore-forming agent, the binder and the sintering aid is 94:4:1:1. Those skilled in the art can understand that the mass ratio of the first aluminum oxide powder, the second aluminum oxide powder, the pore-forming agent, the binder and the sintering aid is about 94:4:1:1, and the present application can also be achieved.

[0059] As preferred, the feeding speed of the spray granulation is 8 Kg / h; those skilled in the art can understand that the feeding speed of the spray granulation can also achieve the present application when it is about 8 Kg / h.

[0060] As preferred, the inlet temperature of the spray granulation is 340℃; those skilled in the art can understand that the inlet temperature of the spray granulation can also achieve the present application when it is about 340℃.

[0061] As preferred, the outlet temperature of the spray granulation is 140℃; those skilled in the art can understand that the outlet temperature of the spray granulation can also achieve the present application when it is about 140℃.

[0062] As preferred, the spraying pressure of the spray granulation is 0.2 MPa. Those skilled in the art can understand that the spraying pressure of the spray granulation can also achieve the present application when it is about 0.2 MPa.

[0063] As preferred, the temperature of the first sintering is 1400℃; those skilled in the art can understand that the temperature of the first sintering can also achieve the present application when it is about 1400℃.

[0064] As preferred, the holding time of the first sintering is 2-5h. Those skilled in the art can understand that the holding time of the first sintering can also achieve the present application when it is about 2-5h.

[0065] As preferred, the first sintering comprises the steps of heating from room temperature to 300℃ at a heating rate of 2-5℃ / min, holding for 1-3h; heating from 300℃ to 1300℃ at a heating rate of 4-10℃ / min; heating from 1300℃ to 1400℃ at a heating rate of 1-3℃ / min, holding for 2-5h. Those skilled in the art can understand that the present application can also be achieved by using similar sintering schedule.

[0066] As preferred, the mass percentage of the third alumina powder, the copper oxide-lanthanum oxide composite powder, the binder, the dispersant and the solvent is (30wt%-10wt%) : (1wt%-3wt%) : (5wt%-10wt%) : (0.5wt%-5wt%) : (50wt%-80wt%). The weight ratio of copper oxide and lanthanum oxide in the copper oxide-lanthanum oxide composite powder is 3-7. Those skilled in the art can understand that the present application can also be achieved by using similar proportions.

[0067] As preferred, the temperature of the second sintering is 1300℃; those skilled in the art can understand that the temperature of the second sintering can also achieve the present application when it is about 1300℃.

[0068] Preferably, the second sintering process is performed for 2-5 hours. Preferably, the second sintering process comprises the steps of heating from room temperature to 300°C at a heating rate of 2-5°C / min, holding for 1-3 hours; heating from 300°C to 1200°C at a heating rate of 4-10°C / min; heating from 1200°C to 1300°C at a heating rate of 1-3°C / min, holding for 2-5 hours. It is understood by those skilled in the art that the second sintering process can also be performed by using a similar sintering schedule.

[0069] The application will be further described in conjunction with specific examples.

[0070] Example 1

[0071] Coarse alumina powder with a particle size of 50 μm, fine alumina powder with a particle size of 5 μm, corn starch, a binder (60 wt% PEG) and a sintering aid (30 wt% silicon dioxide, 30 wt% magnesium oxide, 40 wt% calcium oxide) were mixed in a mass ratio of 94:4:1:1 and placed in a ball mill tank. An equal amount of solvent as the powder was added, and the mixture was ball milled at 200 rpm for 4 hours to obtain a slurry. The slurry was poured into a spray granulation stirring tank for spray granulation to obtain a disc ceramic support powder with uniform particle size distribution and spherical particles. The inlet temperature of the spray granulation was 340°C; the outlet temperature of the spray granulation was 140°C; and the spray pressure of the spray granulation was 0.2 MPa. The spray granulated particles were added to a mold groove that had been sprayed with a release agent, and the mold had a size of an inner diameter of 100 mm, an outer diameter of 160 mm and a thickness of 20 mm. The particles were pressed into a rotary ceramic green body under a 40-ton hydraulic press, and then the green body was transferred to a 100°C oven for drying for 4 hours. The green body was then transferred to a muffle furnace for high-temperature sintering in an air atmosphere. The sintering procedure was as follows: heating from room temperature to 300°C at a heating rate of 1°C / min, holding for 2 hours for degumming; heating from 300°C to 1300°C at a heating rate of 4°C / min for simple heating; heating from 1300°C to 1380°C at a heating rate of 1°C / min, holding for 2 hours for oxidation sintering; and then naturally cooling to room temperature to obtain a disc ceramic membrane support.

[0072] The α-Al2O3 with a particle size of 600 nm, copper oxide-lanthanum oxide composite powder (30%wt copper oxide and 70wt% lanthanum oxide), PVA aqueous solution, sodium polymethylate and water are mixed according to the mass percentage of 27wt%:3wt%:15wt%:3wt%:52wt%; the above raw materials are mixed uniformly according to the proportion, ball milled for 2h to obtain a slurry with uniform mixing and dispersion and good flowability, then the prepared slurry is uniformly coated on a disc ceramic membrane support by dip coating method, then transferred to a 100℃ oven for drying for 2h, then the disc ceramic membrane support with the coated film layer is transferred to a muffle furnace and sintered in air atmosphere, the sintering procedure is as follows: from room temperature to 300℃ at a heating rate of 2℃ / min, heat preservation for 1h for degumming process; from 300℃ to 1200℃ at a heating rate of 4℃ / min for simple heating process; from 1200℃ to 1250℃ at a heating rate of 1℃ / min, heat preservation for 2h for oxidation sintering process; then naturally cooled to room temperature to obtain a disc ceramic membrane with a film layer.

[0073] Example 2

[0074] The coarse alumina powder with a particle size of 50μm, fine alumina powder with a particle size of 5μm, corn starch, binder (40wt% PVA) and sintering aid (30wt% silicon dioxide, 30wt% magnesium oxide, 40wt% calcium oxide) are mixed according to the mass percentage of 94:4:1:1, put into a ball mill tank, and then the same mass of solvent as the powder is added, ball milled at 200rpm for 4h to obtain a slurry. The slurry is poured into a spray granulation stirring tank for spray granulation to obtain a disc ceramic support powder with uniform particle size distribution and spherical particles. The inlet temperature of the spray granulation is 340℃; the outlet temperature of the spray granulation is 140℃; the spray pressure of the spray granulation is 0.2MPa. The spray granulated particles are added to the mold groove which has been sprayed with a release agent, the mold size is a ring cake with an inner diameter of 100mm, an outer diameter of 160mm and a thickness of 20mm, and the ring cake is pressed into a rotary ceramic blank under a 40ton hydraulic machine, then the blank is transferred to a 100℃ oven for drying for 4h, and then transferred to a muffle furnace for high temperature sintering in air atmosphere, the sintering procedure is as follows: from room temperature to 300℃ at a heating rate of 5℃ / min, heat preservation for 3h for degumming process; from 300℃ to 1300℃ at a heating rate of 4℃ / min for simple heating process; from 1300℃ to 1400℃ at a heating rate of 1℃ / min, heat preservation for 5h for oxidation sintering process; then naturally cooled to room temperature to obtain a disc ceramic membrane support.

[0075] The α-Al2O3 with a particle size of 600 nm, copper oxide-lanthanum oxide composite powder (30%wt copper oxide and 70wt% lanthanum oxide), PVA aqueous solution, sodium polymethylate and water are mixed according to the mass percentage of 27wt%:3wt%:15wt%:3wt%:52wt%; the raw materials are mixed uniformly according to the proportion, ball milled for 2h to obtain a slurry which is mixed and dispersed uniformly and has good flowability, then the prepared slurry is uniformly coated on a disc ceramic membrane support by dip coating, then transferred to a 100℃ oven for drying for 2h, and then the disc ceramic membrane support with the coated film layer is transferred to a muffle furnace for sintering in an air atmosphere, and the sintering procedure is as follows: from room temperature to 300℃ at a heating rate of 5℃ / min, heat preservation for 32h to carry out a degumming process; from 300℃ to 1200℃ at a heating rate of 10℃ / min to carry out a simple heating process; from 1200℃ to 1300℃ at a heating rate of 3℃ / min, heat preservation for 5h to carry out an oxidation sintering process; and then naturally cooled to room temperature to obtain a disc ceramic membrane with a film layer.

[0076] Comparative Example 1

[0077] The difference from Example 1 is that the proportion of copper oxide and lanthanum oxide is 45wt% copper oxide and 55% lanthanum oxide, and other operation steps and control parameters are the same as those of Example 1.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that the proportion of copper oxide and lanthanum oxide is 55wt% copper oxide and 45% lanthanum oxide, and other operation steps and control parameters are the same as those of Example 1.

[0080] Comparative Example 3

[0081] The difference from Example 1 is that lanthanum oxide is not added, and copper oxide is used instead of copper oxide-lanthanum oxide composite powder, and other operation steps and control parameters are the same as those of Example 1.

[0082] Comparative Example 4

[0083] The difference from Example 1 is that copper oxide is not added, and lanthanum oxide is used instead of copper oxide-lanthanum oxide composite powder, and other operation steps and control parameters are the same as those of Example 1.

[0084] The performance evaluation method of the disc ceramic membrane prepared in the examples and comparative examples of the application is as follows:

[0085] Bending strength

[0086] Test method: three-point method

[0087] Test instrument: universal testing machine

[0088] Loading speed: 0.5mm / min

[0089] Calculation formula: R = 3FL / 2bh 2

[0090] Wherein R: the value of the sample's flexural strength (MPa); F: the load when the sample is broken (N); L: the span (mm); b: the width of the sample's fracture (mm); h: the height of the sample's fracture (mm)

[0091] Open porosity

[0092] Test method: Archimedes drainage method

[0093] 1. Clean the surface of the sample, dry it in an oven at 100°C until the weight is constant, then naturally cool it to room temperature, and weigh the mass of the sample m1.

[0094] 2. Put the sample into a beaker containing distilled water to ensure that the sample is completely submerged, then heat it to boiling, keep it boiling for 2h, then stop heating, and naturally cool it to room temperature.

[0095] 3. Weigh the mass of the saturated sample in distilled water m2 and the mass of the saturated sample m3. The open porosity P of the sample can be calculated by the following formula: P = (m3-m1) / (m3-m2).

[0096] Pure water flux (L / m 2 *h*bar)

[0097] Temperature: 25°C

[0098] Suction negative pressure: 0.02 MPa

[0099] Membrane surface rotation speed: 300 rpm

[0100] Pure water flux calculation formula: F = Q / A m *t*P

[0101] Wherein F: pure water flux (L / m 2 hbar); Q: the volume of pure water flowing through the membrane surface within the test time (L); A m : membrane filtration area (m 2 ); T: filtration time (h); P: pressure difference on both sides of the filtration membrane (bar)

[0102] Wear rate (μm / h)

[0103] Test method: slurry tank wear

[0104] After 10h accelerated erosion wear in a 1000-mesh silicon carbide slurry with a solid content of 300g / L at 1000 rpm, the thickness change of the membrane layer was determined by a thickness gauge.

[0105] The following table shows the flexural strength, open porosity, pure water flux and abrasion rate data of the examples and comparative examples.

[0106]

[0107]

[0108] Table 1

[0109] From Table 1, it can be seen that in Example 1 and Example 2, when the ratio of copper oxide and aluminum oxide co-doping is 3:7, the prepared disc ceramic membrane achieves a balance between flexural strength and porosity, thereby reflecting a higher pure water filtration flux while exhibiting a low abrasion rate; in Comparative Example 1 and Comparative Example 2, the amount of copper oxide doping is increased (i.e., from 30% to 55%), and the flexural strength of the prepared disc ceramic membrane is significantly improved, but the porosity is also sharply reduced (<30%) and does not meet the application standards of microfiltration membranes. In Comparative Example 3, the amount of lanthanum oxide is completely replaced by copper oxide, and it can be seen that the porosity of the prepared membrane layer without lanthanum oxide doping to form a sheet structure to improve the pore structure of the membrane layer is the lowest compared to the examples; in Comparative Example 4, the amount of copper oxide is completely replaced by lanthanum oxide, and it can be seen that the flexural strength of the prepared membrane layer without copper oxide doping to have a positive densification effect during sintering is the lowest compared to the examples. Therefore, the ratio of copper oxide and lanthanum oxide co-doping in Example 1 and Example 2 to prepare the disc ceramic membrane layer can obtain the optimal performance.

Claims

1. A method for producing a ceramic disk membrane, characterized by, The method comprises the following steps: The first alumina powder, the second alumina powder, the pore-forming agent, the binder and the sintering aid are mixed and first ball-milled to obtain a first slurry; The slurry is spray granulated to form a green body and then first sintered to obtain the disc-shaped ceramic membrane support; The third alumina powder, the copper oxide powder, the lanthanum oxide powder, the binder, the dispersant and the solvent are mixed and second ball-milled to obtain a second slurry; The second slurry is uniformly coated on the disc-shaped ceramic membrane support, and second sintered to load the alumina membrane on the disc-shaped ceramic membrane support to obtain the disc-shaped ceramic membrane; In the alumina film, part of the third alumina powder, copper oxide powder and lanthanum oxide powder form flaky LaAl 11 O 18 when sintering; the flaky LaAl 11 O 18 of adjacent flaky LaAl 11 O 18 are connected to form a three-dimensional interlocking structure of flaky LaAl 11 O 18 and alumina particles in the alumina film; The average particle size of the first alumina powder is 50 μm; The average particle size of the second alumina powder is 5 μm; The average particle size of the third alumina powder is 600 nm; The first sintering temperature is 1380-1400 ℃; The first sintering holding time is 2-5 h; The second sintering temperature is 1250-1300 ℃; The second sintering holding time is 2-5 h.

2. The method according to claim 1, wherein: The pore-forming agent comprises corn starch; The binder comprises PEG or PVA; The sintering aid comprises 30 wt% of silicon dioxide, 30 wt% of magnesium oxide and 40 wt% of calcium oxide.

3. The method of claim 1, wherein: The mass ratio of the first alumina powder, the second alumina powder, the pore-forming agent, the binder and the sintering aid is 94:4:1:

1.

4. The method of claim 1, wherein: The feed rate of the spray granulation is 8 Kg / h; The inlet temperature of the spray granulation is 340 ℃; The outlet temperature of the spray granulation is 140 ℃; The spray pressure of the spray granulation is 0.2 MPa.

5. The method according to claim 1, wherein: The first sintering comprises the steps of: increasing the temperature from room temperature to 300 ℃ at a temperature increasing rate of 2-5 ℃ / min, holding for 1-3 h; increasing the temperature from 300 ℃ to 1300 ℃ at a temperature increasing rate of 4-10 ℃ / min; increasing the temperature from 1300 ℃ to 1400 ℃ at a temperature increasing rate of 1-3 ℃ / min, and holding for 2-5 h.

6. The method according to claim 1, wherein: The mass percentage of the third alumina powder, the copper oxide-lanthanum oxide composite powder, the binder, the dispersant and the solvent is (10 wt%-30 wt%):(1 wt%-3 wt%):(5 wt%-10 wt%):(0.5 wt%-5 wt%):(50 wt%-80 wt%); The weight ratio of copper oxide to lanthanum oxide in the copper oxide-lanthanum oxide composite powder is 3:

7.

7. The method according to claim 1, wherein: The second sintering comprises the steps of: increasing the temperature from room temperature to 300 ℃ at a temperature increasing rate of 2-5 ℃ / min, holding for 1-3 h; increasing the temperature from 300 ℃ to 1200 ℃ at a temperature increasing rate of 4-10 ℃ / min; increasing the temperature from 1200 ℃ to 1300 ℃ at a temperature increasing rate of 1-3 ℃ / min, and holding for 2-5 h.

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