A bimetallic composite oxide modified ceramic membrane and a preparation method and application thereof

Abstract

The application discloses a bimetallic composite oxide modified ceramic membrane and a preparation method and application thereof, and belongs to the technical field of ceramic membranes. The application takes industrial-grade alumina as raw material, reduces the sintering temperature of a ceramic membrane support body by adding a binder, a pore-forming agent, a fluxing agent, an anti-shrinkage agent and the like, and reduces the production cost of the ceramic membrane; a bimetallic oxide composite coating with a catalytic ozonation function is constructed on the surface of the ceramic membrane, oxidation degradation of organic pollutants on the surface of the ceramic membrane is realized, and the anti-pollution performance and service life of the ceramic membrane are improved. The application solves the problems of high production cost and easy membrane pollution of the existing ceramic membrane.

Description

Technical Field

[0001] This invention belongs to the field of ceramic membrane technology, specifically relating to a bimetallic composite oxide modified ceramic membrane, its preparation method, and its application. Background Technology

[0002] Ceramic membranes are a common inorganic membrane separation material, mainly prepared from ceramic raw materials such as TiO2, ZrO2, Al2O3, and SiO2 through specific processes, and possess a hierarchical pore structure. Compared with organic membranes, ceramic membranes have advantages such as high temperature and pressure resistance, high mechanical strength, good chemical stability, long service life, and easy cleaning, and have been successfully applied in water treatment fields such as drinking water purification, removal of natural organic matter, municipal sewage treatment, industrial wastewater reuse, and seawater desalination.

[0003] The production of ceramic membranes involves complex manufacturing processes, including powder preparation, molding, and sintering, as well as the addition of additives such as pore-forming agents, binders, solubilizers, and anti-shrinkage agents. Furthermore, ceramic membranes are brittle and fragile, causing inconvenience during transportation and installation, which increases the cost of using them.

[0004] Besides high production costs, in the process of treating wastewater with ceramic membranes, pollutants in the wastewater inevitably deposit on the surface of the membrane under the influence of polar forces, electrostatic attraction, van der Waals forces, and concentration polarization, forming a dense fouling layer or clogging the membrane pores. This leads to decreased membrane flux, pore blockage, and increased transmembrane pressure, necessitating more frequent physical backwashing and chemical cleaning. Excessive cleaning frequency not only results in significant additional energy consumption and membrane cleaning wastewater but also leads to decreased membrane performance, shortened lifespan, and increased operating costs. Therefore, effectively addressing the problem of ceramic membrane fouling is of great practical significance for expanding the application of ceramic membranes. Summary of the Invention

[0005] In view of the above-mentioned prior art, the present invention provides a bimetallic composite oxide modified ceramic membrane, its preparation method and application, so as to solve the technical problem of easy clogging of existing ceramic membranes.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is to provide a method for preparing a bimetallic composite oxide modified ceramic film, comprising the following steps:

[0007] S1: Alumina powder, binder, pore-forming agent, flux, and anti-shrinkage agent are mixed, and then the mixture is pressed into a ceramic film preform. The ceramic film preform is then subjected to gradient temperature calcination to obtain a ceramic film support. The gradient temperature calcination is as follows: first, the temperature is increased to 900℃ at a heating rate of 5℃ / min and held for 30min; then, the temperature is increased to 1200℃ at a heating rate of 2℃ / min and held for 30min; then, the temperature is increased to 1400~1600℃ at a heating rate of 1℃ / min and held for 2h; or first, the temperature is increased to 900℃ at a heating rate of 5℃ / min and held for 30min; then, the temperature is increased to 1150℃ at a heating rate of 2℃ / min and held for 2h.

[0008] S2: Dissolve the metal salt, urea, and polyvinylpyrrolidone in water to obtain a mixed solution; the metal salt is a mixture of magnesium nitrate and manganese nitrate.

[0009] S3: The ceramic membrane support is immersed in the mixed solution for 4 hours, then baked at 60~120℃ for 4 hours, and then dried and calcined to obtain the bimetallic composite oxide modified ceramic membrane.

[0010] Based on the above technical solution, the present invention can be further improved as follows.

[0011] Furthermore, the mass fraction of the binder in the mixture is 0.5~3%, the mass fraction of the pore-forming agent is 0.05~0.5%, the mass fraction of the flux is 0.5~10%, and the mass fraction of the anti-shrinkage agent is 0.5%.

[0012] Furthermore, the binder is carboxymethyl cellulose, polyvinyl alcohol, or polyvinylpyrrolidone; the pore-forming agent is ammonium chloride, starch, or sodium alginate; the flux is boric acid, calcium oxide, or aluminum phosphate; and the anti-shrinkage agent is sodium carbonate.

[0013] Furthermore, the pressure during the pressing of the mixture in S1 is 20t.

[0014] Furthermore, the mass ratio of magnesium nitrate to manganese nitrate in the metal salt is 2:1.

[0015] Furthermore, the molar ratio of urea to metal salt in the mixed solution is 3~6:1.

[0016] Furthermore, the concentration of urea in the mixed solution is 0.33 mol / L; the concentration of polyvinylpyrrolidone is 10 g / L.

[0017] Furthermore, in S4, drying is performed at 105°C for 2 hours; calcination is performed at 550°C for 2 hours.

[0018] The present invention also discloses a bimetallic composite oxide modified ceramic film prepared by the above preparation method.

[0019] The present invention also discloses the application of the above-mentioned bimetallic composite oxide modified ceramic membrane in the filtration or catalytic ozonation treatment of bovine serum albumin.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses readily available and inexpensive industrial-grade alumina to produce a self-made ceramic membrane with high strength and good filtration performance by optimizing the material formula. It also endows the ceramic membrane with ozone catalytic properties, improves the membrane's anti-fouling performance, increases its service life, and reduces the production cost of the ceramic membrane.

[0022] 2. This invention uses transition metal manganese and alkaline earth metal magnesium as a control strategy, which can increase the number of acidic and alkaline sites on the surface of the ceramic membrane, thereby improving the catalytic ozonation efficiency of the ceramic membrane and enhancing the filtration efficiency of the catalytic ceramic membrane.

[0023] 3. In-situ coupling of ceramic membrane with catalytic ozone not only solves the problem of difficult recovery of powdered catalyst, but also further improves the anti-fouling ability of ceramic membrane. Attached Figure Description

[0024] Figure 1 The SEM characterization results are those of the bimetallic composite oxide modified ceramic film Mn-Mg / CM-H prepared in Example 1 and the ceramic film CM-H prepared in Comparative Example 1.

[0025] Figure 2 The pore size analysis diagrams are shown for the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1.

[0026] Figure 3 The images show the results of filtering bovine serum albumin using the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1.

[0027] Figure 4 The image shows the results of in-situ coupled catalytic ozonolysis of bovine serum albumin using the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below with reference to examples. Example 1

[0029] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0030] (1) Alumina powder, polyvinylpyrrolidone (PVP), starch, boric acid and sodium carbonate are mixed evenly to obtain a mixture. The mass fractions of PVP, starch, boric acid and sodium carbonate in the mixture are 1%, 0.1%, 5% and 0.5% respectively, and the remainder is alumina powder. The mixture is then transferred to a mold and pressed into a ceramic membrane preform with a pressure of 20t. The ceramic membrane preform is then placed in a muffle furnace and heated to 900℃ at a heating rate of 5℃ / min and held for 30min to remove organic matter. Then it is heated to 1200℃ at a heating rate of 2℃ / min and held for 30min. Finally, it is heated to 1500℃ at a heating rate of 1℃ / min and calcined for 2h to ceramicize the preform and generate a ceramic membrane support with high strength and good stability.

[0031] (2) Magnesium nitrate, manganese nitrate, urea and PVP are dissolved in water to prepare a mixed solution. In the mixed solution, the mass ratio of magnesium nitrate to manganese nitrate is 2:1, the molar ratio of urea to metal salt is 4.5:1, the concentration of urea is 0.33 mol / L, and the concentration of PVP is 10 g / L. The ceramic membrane support obtained in step (1) is placed in the mixed solution and immersed for 4 h. Then it is transferred to an oven and baked at 80 °C for 4 h. Then it is dried at 105 °C for 2 h to obtain a modified ceramic membrane preform. Finally, it is calcined at 550 °C for 2 h to obtain a bimetallic composite oxide modified ceramic membrane, denoted as Mn-Mg / CM-H. Example 2

[0032] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0033] Replace polyvinylpyrrolidone (PVP) in step (1) with carboxymethyl cellulose, and the rest is the same as in Example 1. Example 3

[0034] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0035] Replace polyvinylpyrrolidone (PVP) in step (1) with polyvinyl alcohol, and the rest is the same as in Example 1. Example 4

[0036] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0037] The mass fraction of polyvinylpyrrolidone (PVP) in step (1) was adjusted to 0.5%, and the rest was the same as in Example 1. Example 5

[0038] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0039] The mass fraction of polyvinylpyrrolidone (PVP) in step (1) was adjusted to 1.5%, and the rest was the same as in Example 1. Example 6

[0040] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0041] The mass fraction of polyvinylpyrrolidone (PVP) in step (1) was adjusted to 3%, and the rest was the same as in Example 1. Example 7

[0042] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0043] Replace the starch in step (1) with ammonium chloride, and the rest is the same as in Example 1. Example 8

[0044] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0045] Replace the starch in step (1) with sodium alginate, and the rest is the same as in Example 1. Example 9

[0046] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0047] The mass fraction of starch in step (1) was adjusted to 0.05%, and the rest was the same as in Example 1. Example 10

[0048] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0049] The mass fraction of starch in step (1) was adjusted to 0.3%, and the rest was the same as in Example 1. Example 11

[0050] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0051] The mass fraction of starch in step (1) was adjusted to 0.5%, and the rest was the same as in Example 1. Example 12

[0052] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0053] Replace boric acid in step (1) with calcium oxide, and the rest is the same as in Example 1. Example 13

[0054] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0055] Replace boric acid in step (1) with aluminum phosphate, and the rest is the same as in Example 1. Example 14

[0056] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0057] The mass fraction of boric acid in step (1) was adjusted to 0.5%, and the rest was the same as in Example 1. Example 15

[0058] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0059] The mass fraction of boric acid in step (1) was adjusted to 3%, and the rest was the same as in Example 1. Example 16

[0060] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0061] The mass fraction of boric acid in step (1) was adjusted to 10%, and the rest was the same as in Example 1. Example 17

[0062] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0063] (1) Alumina powder, polyvinylpyrrolidone (PVP), starch, boric acid and sodium carbonate are mixed evenly to obtain a mixture. The mass fractions of PVP, starch, boric acid and sodium carbonate in the mixture are 1%, 0.1%, 5% and 0.5% respectively, and the remainder is alumina powder. The mixture is then transferred to a mold and pressed into a ceramic membrane preform with a pressure of 20t. The ceramic membrane preform is then placed in a muffle furnace and heated to 900℃ at a heating rate of 5℃ / min and held for 30min to remove organic matter. Then it is heated to 1100℃ at a heating rate of 2℃ / min and calcined for 2h to ceramicize the preform and generate a ceramic membrane support with high strength and good stability.

[0064] (2) Magnesium nitrate, manganese nitrate, urea and PVP are dissolved in water to prepare a mixed solution. In the mixed solution, the mass ratio of magnesium nitrate to manganese nitrate is 2:1, the molar ratio of urea to metal salt is 4.5:1, the concentration of urea is 0.33 mol / L, and the concentration of PVP is 10 g / L. The ceramic membrane support obtained in step (1) is placed in the mixed solution and immersed for 4 h. Then it is transferred to an oven and baked at 80 °C for 4 h. Then it is dried at 105 °C for 2 h to obtain a modified ceramic membrane preform. Finally, it is calcined at 550 °C for 2 h to obtain a bimetallic composite oxide modified ceramic membrane. Example 18

[0065] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0066] The final roasting temperature in step (1) was adjusted to 1400℃, and the rest was the same as in Example 1. Example 19

[0067] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0068] The final roasting temperature in step (1) was adjusted to 1600℃, and the rest was the same as in Example 1. Example 20

[0069] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0070] The molar ratio of urea to metal salt in step (2) is adjusted to 3:1, and the rest is the same as in Example 1. Example 21

[0071] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0072] The molar ratio of urea to metal salt in step (2) is adjusted to 6:1, and the rest is the same as in Example 1. Example 22

[0073] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0074] The baking reaction temperature in step (2) was adjusted to 60°C, and the rest was the same as in Example 1. Example 23

[0075] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0076] The baking reaction temperature in step (2) was adjusted to 100°C, and the rest was the same as in Example 1. Example 24

[0077] A bimetallic composite oxide modified ceramic membrane is prepared by the following steps:

[0078] The baking reaction temperature in step (2) was adjusted to 100°C, and the rest was the same as in Example 1.

[0079] Comparative Example 1

[0080] A ceramic membrane is prepared by the following steps:

[0081] Alumina powder, polyvinylpyrrolidone (PVP), starch, boric acid, and sodium carbonate were mixed evenly to obtain a mixture. The mass fractions of PVP, starch, boric acid, and sodium carbonate in the mixture were 1%, 0.1%, 5%, and 0.5%, respectively, with the remainder being alumina powder. The mixture was then transferred to a mold and pressed into a ceramic membrane preform under a pressure of 20t. The ceramic membrane preform was then placed in a muffle furnace and heated to 900℃ at a heating rate of 5℃ / min, held for 30min to remove organic matter, then heated to 1200℃ at a heating rate of 2℃ / min, held for 30min, and finally heated to 1500℃ at a heating rate of 1℃ / min and calcined for 2h to ceramicize the preform, thereby generating a ceramic membrane with high strength and good stability, denoted as CM-H.

[0082] Results Analysis

[0083] The bimetallic composite oxide modified ceramic film Mn-Mg / CM-H prepared in Example 1 and the ceramic film CM-H prepared in Comparative Example 1 were characterized by SEM, and the results are as follows: Figure 1 As shown. From Figure 1 As can be seen, due to the use of industrial-grade alumina as raw material, the alumina particles of different sizes accumulate to form a pore structure of varying sizes. Therefore, CM-H exhibits poor selectivity, resulting in unstable membrane flux and retention rate during the filtration process. After applying a Mn-Mg metal oxide coating, smaller Mn and Mg oxide particles are dispersed on the Al2O3 particles, repairing some of the pore structure and making the overall pore size of Mn-Mg / CM-H more uniform.

[0084] The pore size of the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1 were analyzed and characterized. The results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the pore size distribution of CM-H is relatively wide (220~400nm), while the pore size distribution of the Mn-Mg / CM-H film is 100nm; this indicates that the pore size distribution of the ceramic film is significantly more uniform after loading the active components (Mn and Mg oxide particles), and the active component coating repairs the pore defects of the original film. This may be because MnO x The particles are fine and well-dispersed. Generally, ceramic ultrafiltration membranes have a pore size of 1-100 nm, while CM-H has a larger pore size and lower selectivity for pollutants. After modification by co-precipitation, the pore structure of Mn-Mg / CM-H is improved, and the selectivity is significantly enhanced. The results show that the ceramic membrane modified by the method of this invention can effectively improve the filtration efficiency of the membrane itself.

[0085] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 2-3 were evaluated, and the results are shown in Table 1.

[0086] Table 1

[0087] Types of adhesives Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° PVP 140.3 17.54 0.266 46.04 Carboxymethyl cellulose 145.7 17.12 0.244 38.32 Polyvinyl alcohol 141.8 17.49 0.231 43.81

[0088] Table 1 shows that the three binders do not differ significantly in most probable pore size and linear shrinkage. Carboxymethyl cellulose and polyvinyl alcohol (PVA) show slightly better improvement in hydrophilicity than PVP, likely due to the former's high carboxyl or hydroxyl content. However, the compressive strength data indicates that the ceramic membrane support using PVP exhibits superior compressive strength compared to the other two binders. Furthermore, PVP demonstrates better water solubility and thermal stability than the other two binders, and its preparation process is simpler and more feasible.

[0089] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 4 to 6 were evaluated, and the results are shown in Table 2.

[0090] Table 2

[0091] PVP dosage increased Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 0.5% 116.8 17.19 0.214 60.34 1.0% 140.3 17.54 0.266 46.04 1.5% 149.8 17.19 0.273 27.88 3.0% 172.9 17.22 0.288 24.32

[0092] Table 2 shows that when the PVP content is 0.5%, the pore size is mainly distributed between 100 and 120 nm, and the distribution is relatively uniform. With increasing PVP content, the pore size increases and the distribution becomes wider, indicating that PVP also has a pore-forming effect. Hydrophilicity tests show that with increasing PVP content, the water contact angle decreases and hydrophilicity increases. This may be because the PVP molecular structure contains a large number of acyl groups, which have strong polarity and can form hydrogen bonds with water molecules, thus resulting in strong hydrophilicity. The PVP content has little effect on the linear shrinkage rate but significantly improves the support strength. When the PVP content increases from 0.5% to 1.0%, the compressive strength increases from 0.214 MPa to 0.266 MPa. However, further increases to 1.5% (0.273 MPa) and 3.0% (0.288 MPa) show little increase in strength, and a small number of cracks appear after sintering.

[0093] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 7-8 were evaluated, and the results are shown in Table 3.

[0094] Table 3

[0095] Types of pore-forming agents Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° starch 140.3 17.54 0.266 46.04 ammonium chloride 155.7 19.20 0.219 38.32 Sodium alginate 131.8 16.31 0.275 36.31

[0096] Table 3 shows that the three pore-forming agents do not exhibit significant differences in performance for the ceramic membrane support. Sodium alginate is slightly superior to the other two, but it is more expensive and the uniformity of the pores it generates is more difficult to control. Ammonium chloride releases a small amount of gas during calcination, which has a certain impact on the strength of the support.

[0097] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 9 to 11 was evaluated, and the results are shown in Table 4.

[0098] Table 4

[0099] Starch addition Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 0.05% 136.8 19.33 0.234 63.15 0.10% 140.3 17.54 0.266 46.04 0.30% 159.5 17.24 0.263 45.33 0.50% 162.9 16.51 0.270 44.29

[0100] As shown in Table 4, the compressive strength is low and the pore size distribution is uneven when the starch content is 0.05%, which may be related to the dispersibility of starch. Increasing the starch content makes the compressive strength and pore size distribution more uniform, but further increases do not significantly improve the strength.

[0101] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 12-13 were evaluated, and the results are shown in Table 5.

[0102] Table 5

[0103] Types of flux Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° Boric acid 140.3 17.54 0.266 46.04 Calcium oxide 135.7 18.22 0.217 41.12 Sodium phosphate 133.6 17.31 0.232 43.71

[0104] As can be seen from Table 5, the compressive strength of the ceramic film support prepared by using boric acid as a flux is higher than that of the other two fluxes. This may be because boric acid can significantly reduce the temperature required for ceramicization during the sintering process of the support, thus exhibiting higher mechanical strength at the same calcination temperature.

[0105] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 14-16 were evaluated, and the results are shown in Table 6.

[0106] Table 6

[0107] Boric acid dosage Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 0.5% 122.1 19.33 0.153 63.15 3.0% 153.1 22.11 0.173 51.27 5.0% 140.3 17.54 0.266 46.04 10.0% 313.2 12.14 0.134 46.29

[0108] As shown in Table 6, boric acid has a relatively small impact on the hydrophilicity of the support. The average pore size initially decreases and then increases with increasing boric acid content, indicating that an appropriate amount of boric acid can lead to more ordered grain growth in the support, resulting in a more uniform pore structure. The compressive strength exhibits the same trend. During the sintering process, boric acid forms a thin film on the surface of the ceramic particles, enhancing the bonding force between them and thus improving the mechanical strength of the support. Therefore, as the boric acid content increases from 3% (0.173 MPa) to 5% (0.266 MPa), the support strength improves, but further increases to 10% (0.134 MPa) and then significantly decreases. This may be because excessive glass phase inhibits grain growth, leading to an uneven microstructure and reduced mechanical strength.

[0109] The performance of the ceramic membrane CM-H prepared in Comparative Example 1 and the ceramic membrane supports prepared in Examples 17-19 were evaluated, and the results are shown in Table 7.

[0110] Table 7

[0111] Calcination temperature / °C Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 1100 375.1 8.63 0.083 69.17 1300 153.1 15.32 0.163 54.37 1500 140.3 17.54 0.266 46.04 1600 354.8 20.70 0.379 20.14

[0112] As shown in Table 7, with increasing sintering temperature, the pore size and distribution of the support film exhibit a trend of first decreasing and then increasing. This may be because at 1100℃, the support is not sufficiently ceramicized, resulting in weak bonding between ceramic particles and larger gaps. As the temperature increases to 1500℃, the bonding between ceramic particles strengthens, the gaps gradually decrease, and thus the pore size gradually shrinks. When the temperature further increases to 1600℃, grain growth and sintering shrinkage may occur, causing the pore size to increase again. The trend of water contact angle variation is consistent with that of pore size distribution and average pore size. Calcination temperature has a significant effect on linear shrinkage and compressive strength; with increasing calcination temperature, the linear shrinkage also increases. This is because higher temperatures result in a higher degree of ceramicization of the support, stronger bonding between ceramic particles, and more pronounced grain growth and sintering shrinkage. Therefore, its compressive strength is also significantly enhanced.

[0113] The performance of the bimetallic composite oxide modified ceramic films prepared in Examples 1 and 20-21 was evaluated, and the results are shown in Table 8.

[0114] Table 8

[0115] Increase urea dosage Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 3.0：1 110.3 17.34 0.264 36.44 4.5：1 100.7 17.62 0.260 30.12 6.0：1 123.8 17.57 0.259 33.46

[0116] As can be seen from Table 8, the support used in step (2) of Examples 1 and 20-21 is the same, so the linear shrinkage rate and compressive strength of the final bimetallic composite oxide modified ceramic film do not change much. Urea, as a precipitant, decomposes at high temperature, which can cause the metal salt to precipitate uniformly on the surface and inside of the support, and then form an active coating after drying and calcination. The active coating can further modify the pore structure of the support, making its pore size appropriate and its distribution more uniform. If too little urea is added, the reaction is incomplete, and the repair effect on the pores is not obvious. If too much is added, the reaction rate is faster, and the precipitation of metal salts is more disordered.

[0117] The performance of the bimetallic composite oxide modified ceramic films prepared in Examples 1 and 22-23 was evaluated, and the results are shown in Table 9.

[0118] Table 9

[0119] Reaction temperature / ℃ Most probable pore size / nm Linear shrinkage rate / % Compressive strength / MPa Water contact angle / ° 60 109.3 17.58 0.261 37.77 80 100.7 17.62 0.260 30.12 100 119.3 17.71 0.258 36.67 120 137.6 17.60 0.268 38.29

[0120] As can be seen from Table 9, when the reaction temperature is low, the reaction rate is slow, the reaction process is incomplete, and the pore size of the bimetallic composite oxide modified ceramic membrane is slightly larger. However, when the reaction temperature is too high, the reaction is violent, the precipitation process of metal salt is more disordered, and the pore size distribution is uneven.

[0121] The performance of the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1 in filtering bovine serum albumin (BSA) was evaluated on a high-pressure flat-panel membrane filtration device. The procedure was as follows: At room temperature, the main pump speed was 40 rpm, and the membrane inlet pressure was 0.1 MPa. BSA with an initial concentration of 1.0 g / L was treated using a circulating filtration mode. Permeate was continuously sampled, and the permeate volume and BSA concentration were measured. The results are shown in [Figure 1]. Figure 3 .Depend on Figure 3 It can be seen that the flux change rate of the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H is smaller than that of the unmodified ceramic membrane CM-H, indicating better antifouling performance. This is because bimetallic oxide modification can enhance the hydrophilicity of the ceramic membrane, thereby enhancing the repulsion between the membrane surface and pollutants. At the same time, the modified ceramic membrane has a higher rejection rate, indicating that its filtration performance is superior to that of the unmodified ceramic membrane.

[0122] The performance of the bimetallic composite oxide modified ceramic membrane Mn-Mg / CM-H prepared in Example 1 and the ceramic membrane CM-H prepared in Comparative Example 1 in the coupled catalytic ozonolysis treatment of bovine serum albumin was evaluated. The ozone flow rate was 1 L / min. The results are shown in […]. Figure 4 .Depend on Figure 4 It can be seen that the flux of both membranes decreased rapidly, and at 50 min, their J... t The / J0 values ​​were both 10% lower, indicating severe clogging of both membranes at this point. This is because BSA degradation generated a large number of intermediate products of varying sizes and properties, causing severe membrane fouling. Subsequently, a difference in flux gradually appeared between the modified and unmodified membranes, with the flux of the modified membrane gradually recovering. In the later stages of filtration, the modified ceramic membrane exhibited higher flux, due to its stronger catalytic activity, which enabled it to mineralize contaminants on its surface and within its pores. This indicates that in-situ coupled catalytic ozonation using modified ceramic membranes is an effective strategy for improving the antifouling ability of ceramic membranes.

[0123] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.

Claims

1. A method for producing a ceramic membrane modified with a double metal complex oxide, characterized by, The method comprises the following steps: S1: mixing alumina powder, a binder, a pore-forming agent, a fluxing agent and an anti-shrinkage agent, then pressing the mixture into a ceramic membrane embryo, and then baking the ceramic membrane embryo through gradient temperature rising to obtain a ceramic membrane support; the mass fraction of the binder in the mixture is 0.5-3%, the mass fraction of the pore-forming agent is 0.05-0.5%, the mass fraction of the fluxing agent is 0.5-10%, and the mass fraction of the anti-shrinkage agent is 0.5%; the binder is carboxymethyl cellulose, polyvinyl alcohol or polyvinylpyrrolidone; the pore-forming agent is ammonium chloride, starch or sodium alginate; the fluxing agent is boric acid, calcium oxide or aluminum phosphate; the anti-shrinkage agent is sodium carbonate; the gradient temperature rising baking is: first rising the temperature to 900℃ at a temperature rising rate of 5℃ / min, keeping the temperature for 30 min, then rising the temperature to 1200℃ at a temperature rising rate of 2℃ / min, keeping the temperature for 30 min, and then rising the temperature to 1400-1600℃ at a temperature rising rate of 1℃ / min, keeping the temperature for 2 h of calcination; S2: co-dissolving a metal salt, urea and polyvinylpyrrolidone in water to obtain a mixed solution; the metal salt is a mixture of magnesium nitrate and manganese nitrate; S3: placing the ceramic membrane support into the mixed solution, immersing for 4 h, then baking at 60-120℃ for 4 h, and then drying and calcining to obtain a bimetallic composite oxide modified ceramic membrane.

2. The method of claim 1, wherein: The pressure for pressing the mixture in S1 is 20 t.

3. The method of claim 1, wherein: The mass ratio of magnesium nitrate to manganese nitrate in the metal salt is 2:

1.

4. The method of claim 3, wherein: The molar ratio of urea to the metal salt in the mixed solution is 3-6:

1.

5. The method of claim 4, wherein: The concentration of urea in the mixed solution is 0.33 mol / L; and the concentration of polyvinylpyrrolidone is 10 g / L.

6. The method of claim 1, wherein: The drying in S4 is drying at 105℃ for 2 h; and the calcining is calcining at 550℃ for 2 h.

7. The bimetallic composite oxide modified ceramic membrane prepared by the preparation method in any one of claims 1-6.

8. The use of the bimetallic composite oxide modified ceramic membrane in claim 7 in filtering bovine serum protein or catalyzing ozone oxidation treatment of bovine serum protein.

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