Low-defect high-precision ceramic ultrafiltration support and preparation method thereof

Abstract

The application discloses a kind of low-defect high-precision ceramic ultrafiltration support and preparation method thereof, it is related to ceramic membrane technical field, the raw and auxiliary materials of ceramic ultrafiltration support include alumina powder 100 parts, kaolin 5-20 parts, sintering aid 5-10 parts, sodium carboxymethyl cellulose 0.1-1 part, pore-forming agent 1-10 parts, sodium tripolyphosphate 0.1-1 part, sodium hexametaphosphate 0.5-3 parts, water 100 parts, the particle size D50 of alumina powder is 0.5-3 μm, and particle size distribution (D90-D10) / D50≤3.0;Its preparation method includes batching, raw material wet ball milling, slurry grading, grouting forming, drying, sintering, polishing and grinding, cutting steps.The application provides a kind of low-defect high-precision ceramic ultrafiltration support preparation method, using the mode of grouting forming, by slurry grading, finally get the size of particle size appropriate, distribution is narrow raw and auxiliary material mixed even slurry, ensure that the support aperture distribution is narrow finally obtained, simultaneously aperture is smaller to reach ultrafiltration level.

Description

Technical Field

[0001] This invention relates to the field of ceramic membrane technology, and in particular to a low-defect, high-precision ceramic ultrafiltration support and its preparation method. Background Technology

[0002] Ceramic membranes are asymmetric membrane materials formed from inorganic powders as the main raw materials through molding, drying, and sintering. Ceramic membranes generally consist of a support and a separation layer. The support directly affects the strength, flux, and pore size distribution of the ceramic membrane, and directly determines whether the separation layer has a large bubble point pore size. This is especially important for the bubble point pore size and even the filtration accuracy of nanofiltration and molecular sieve-level ceramic membranes.

[0003] Currently, ceramic membrane supports typically have pore sizes between 0.1 μm and 10 μm. The ratio of (bubble point pore size - minimum pore size) to most probable pore size is generally 3-5, indicating large pore sizes and a wide pore size distribution. This is mainly because current supports are primarily manufactured using extrusion processes. Limited by the preparation and mixing methods of solid raw materials, it is difficult to improve the uniformity of the raw material and auxiliary material mixture. It is also difficult to remove excessively large or small particles of raw materials and auxiliary materials at the micron level, resulting in a wide and non-concentrated particle size distribution of the raw materials and auxiliary materials, thus leading to a wide pore size distribution in the final support. This also indirectly affects the separation of nanofiltration and molecular sieve membranes when coating the support. The process of extrusion requires multiple transition layers, which is complex and prone to various instabilities. Furthermore, the surface of the coated membrane is not smooth enough, which is detrimental to the coating stability of nanofiltration and molecular sieve membranes. Given the uneven particle size distribution of raw materials in extrusion processes, a slurry casting method is considered to directly prepare ultrafiltration-grade supports. Wet ball milling is used to disperse the raw materials, greatly improving the mixing uniformity. Particle size classification using liquid slurry ensures the overall particle size distribution of the raw materials, effectively overcoming the defects of the extrusion process. Therefore, developing a low-defect, high-precision ceramic ultrafiltration support preparation method is of significant importance. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a low-defect, high-precision ceramic ultrafiltration support and its preparation method, so as to reduce the pore size distribution of the support while achieving ultrafiltration level with a small pore size.

[0005] In a first aspect, the present invention provides a low-defect, high-precision ceramic ultrafiltration support, the ceramic ultrafiltration support comprising the following raw materials in parts by weight: 100 parts alumina powder, 5-20 parts kaolin, 5-10 parts sintering aid, 0.1-1 parts sodium carboxymethyl cellulose, 1-10 parts pore-forming agent, 0.1-1 parts sodium tripolyphosphate, 0.5-3 parts sodium hexametaphosphate, and 100 parts water, wherein the alumina powder has a particle size D50 of 0.5-3 μm and a particle size distribution (D90-D10) / D50 ≤ 3.0.

[0006] In conjunction with the first aspect, in some embodiments, the sintering aid is one or more of magnesium oxide, yttrium oxide, titanium oxide, and zirconium oxide.

[0007] In conjunction with the first aspect, in some embodiments, the pore-forming agent is one or more of corn starch, tapioca starch, and pea starch.

[0008] Secondly, the present invention provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support, comprising the following steps:

[0009] 1) Ingredients: Weigh alumina powder, sintering aid, sodium carboxymethyl cellulose, pore-forming agent, sodium tripolyphosphate, sodium hexametaphosphate and water separately, mix them to obtain raw and auxiliary materials;

[0010] 2) Wet ball milling of raw materials: All raw and auxiliary materials are loaded into a ball mill jar, and then the ball mill jar is placed in a roller ball mill for ball milling. Then the mixture is passed through a 100-mesh sieve until the particle size D50 of the slurry is in the range of 0.2-1μm to obtain the slurry.

[0011] 3) Slurry classification: Let the obtained slurry stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry, and pour the remaining 9 / 10 volume of slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry again, and pour the remaining 9 / 10 volume of slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry again. Add a suspending agent to the remaining slurry and stir for 3-10 hours to obtain the classified slurry. During the slurry classification process, after each ball milling, control the slurry particle size to be within the D50 range of 0.2-1μm.

[0012] 4) Slurry casting: Pour the graded slurry into the plaster mold, let the slurry stand for 10-30 minutes, then pour out the excess slurry, and place the mold at room temperature for 3-24 hours to obtain a wet blank;

[0013] 5) Drying: Place the demolded support into an oven to dry, obtaining a dry blank;

[0014] 6) Sintering: The dried blanks are placed in a kiln and sintered at high temperature, and then cooled naturally to obtain a rough ceramic film support.

[0015] 7) Polishing and grinding: The rough ceramic membrane support is placed in a polishing machine for polishing and grinding, then cut, and dried again to obtain the ceramic ultrafiltration support.

[0016] In conjunction with the second aspect, in some embodiments, during the ball milling process described in step 2), the mass ratio of raw materials and grinding balls is 1:1, the grinding balls are selected from high-alumina grinding balls with diameters of 5mm, 3mm, and 1mm, the mass ratio of high-alumina grinding balls with diameters of 5mm, 3mm, and 1mm is 3:5:2, the ball mill speed is 10r / min, and the ball milling time is 8-24h.

[0017] In conjunction with the second aspect, in some embodiments, the mass ratio of alumina powder to suspending agent in step 3) is 100:0.1-5.

[0018] In conjunction with the second aspect, in some embodiments, the drying temperature in step 5) is 80°C, the drying time is 4-8 hours, and the drying heating rate is 1°C / min.

[0019] In conjunction with the second aspect, in some embodiments, the heating regime for high-temperature sintering described in step 6) is as follows: first, heat to 200°C in 3-5 hours, then heat to 1190-1350°C in 4-6 hours, and then hold at that temperature for 2-4 hours.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support. The method uses a slurry casting process, and through slurry classification, a uniformly mixed slurry of raw and auxiliary materials with appropriate particle size and narrow distribution is finally obtained. This ensures that the final support has a narrow pore size distribution and a small pore size that meets ultrafiltration standards.

[0022] 2. The support obtained by the present invention is used for coating nanofiltration membranes and molecular sieve membranes, which greatly reduces the number of coating times and can even directly coat nanofiltration membranes, significantly improving the stability of the coating. Attached Figure Description

[0023] Figure 1 The images show the SEM image and pore size distribution of the ceramic ultrafiltration support prepared in Example 1 of this invention.

[0024] Figure 2 The images show the SEM image and pore size distribution of the ceramic ultrafiltration support prepared in Example 2 of this invention.

[0025] Figure 3 The images show the SEM image and pore size distribution of the ceramic ultrafiltration support prepared in Example 3 of this invention. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified in the following examples, the conditions are as per standard conditions or the manufacturer's recommendations. Raw materials, equipment, or instruments whose manufacturers are not specified are all commercially available products.

[0028] This invention proposes a low-defect, high-precision ceramic ultrafiltration support and its preparation method, comprising 100 parts of alumina powder, 5-20 parts of kaolin, 5-10 parts of sintering aid, 0.1-1 parts of sodium carboxymethyl cellulose, 1-10 parts of pore-forming agent, 0.1-1 parts of sodium tripolyphosphate, 0.5-3 parts of sodium hexametaphosphate, and 100 parts of water. The alumina powder has a particle size D50 of 0.5-3 μm, and the particle size distribution (D90-D10) / D50 ≤ 3.0. The preparation method includes batching, wet ball milling of raw materials, slurry classification, slip casting, drying, sintering, polishing, and cutting steps. The ceramic ultrafiltration support of this invention adopts a slip casting method. Through slurry classification, a uniformly mixed slurry of raw materials with suitable particle size and narrow distribution is finally obtained, ensuring that the final support has a narrow pore size distribution and a small pore size that meets ultrafiltration standards.

[0029] The present invention provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support, comprising the following steps:

[0030] 1) Batching: Mix 100 parts of alumina powder with a particle size D50 of 0.5-3μm and a particle size distribution (D90-D10) / D50≤3.0; 5-20 parts of kaolin; 5-10 parts of sintering aid; 0.1-1 parts of sodium carboxymethyl cellulose; 1-10 parts of pore-forming agent; 0.1-1 parts of sodium tripolyphosphate; 0.5-3 parts of sodium hexametaphosphate; and 100 parts of water to obtain the raw and auxiliary materials; the sintering aid is one or more oxides such as magnesium oxide, yttrium oxide, titanium oxide, and zirconium oxide; the pore-forming agent is one or more of corn starch, cassava starch, and pea starch.

[0031] 2) Wet ball milling of raw materials: Load all the raw and auxiliary materials prepared above into a ball mill jar. The mass ratio of raw and auxiliary materials to ball milling beads is 1:1. High alumina ball milling beads with diameters of 5mm, 3mm, and 1mm are selected. The mass ratio of high alumina ball milling beads with diameters of 5mm, 3mm, and 1mm is 3:5:2. Place the ball mill jar on a roller ball mill. The ball mill speed is 10r / min. The ball milling time is 8-24h. Pour the slurry out of the ball mill jar. Pass the slurry through a 100-mesh sieve until the particle size D50 of the slurry is in the range of 0.2-1μm. If the requirements are not met, reduce or increase the ball milling time to finally obtain the slurry.

[0032] 3) Slurry classification: Let the obtained slurry stand for 3-10 minutes, then pour off 1 / 10 of the upper slurry volume, and pour the remaining 9 / 10 of the slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 of the upper slurry volume again, and pour the remaining 9 / 10 of the slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 of the upper slurry volume again, add a suspending agent to the remaining slurry, and stir for 3-10 hours to obtain the classified slurry. During the slurry classification process, after each ball milling, control the slurry particle size to be within the D50 range of 0.2-1μm. Because the raw materials and auxiliary materials are ground smooth by the roller ball mill, the smaller particle size of the ground-off particles results in a wider pore size distribution. In addition, the resulting slurry has a certain degree of suspension, but at the same time, it settles at a very slow rate. The settling rate is related to the particle size of the raw materials and auxiliary materials. The smaller the particle size of the raw materials and auxiliary materials, the slower they settle. After three treatments, the raw materials and auxiliary materials are classified. Then, a suspending agent is added to ensure the stability of the slurry. At the same time, the particle size of the raw materials and auxiliary materials is controlled in each ball milling process. Finally, a uniformly mixed slurry of raw materials and auxiliary materials with a suitable particle size and a narrow distribution is obtained.

[0033] 4) Slurry casting: Pour the graded slurry into the prepared plaster mold. Let the slurry stand for 10-30 minutes. After the time is up, pour out the excess slurry. Place the mold at room temperature for 3-24 hours to ensure that the support can be demolded and has a certain strength, thus obtaining a wet blank.

[0034] 5) Drying: Place the demolded support into an oven to dry at a temperature of 80℃ for 4-8 hours at a heating rate of 1℃ / min to obtain a dry blank.

[0035] 6) Sintering: The dried blanks are placed in a kiln for sintering. The heating regime is as follows: first, heat the blanks to 200℃ in 3-5 hours, then heat the blanks to 1190-1350℃ in 4-6 hours, and then hold the blanks for 2-4 hours to obtain a coarse ceramic film support.

[0036] 7) Polishing and grinding: The sintered support is placed in a polishing machine for polishing and grinding until it reaches the required size. After subsequent cutting and drying, the ceramic ultrafiltration support is obtained.

[0037] The following examples 1-15 illustrate in detail a low-defect, high-precision ceramic ultrafiltration support and its preparation method according to the present invention.

[0038] Example 1

[0039] This embodiment provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support, the steps of which are as follows:

[0040] 1) Ingredients: Mix 500g of alumina powder with a particle size D50 of 0.5μm and a particle size distribution (D90-D10) / D50≤3.0, 25g of kaolin, 25g of magnesium oxide, 0.5g of sodium carboxymethyl cellulose, 5g of corn starch, 0.5g of sodium tripolyphosphate, 2.5g of sodium hexametaphosphate, and 500g of water to obtain the raw and auxiliary materials.

[0041] 2) Wet ball milling of raw materials: Load all the raw and auxiliary materials prepared above into a ball mill jar, and add 317.55g, 529.25g, and 217.7g of high-alumina ball milling beads with diameters of 5mm, 3mm, and 1mm respectively; place the ball mill jar on a roller ball mill, with the ball mill speed at 10r / min and the ball milling time at 8h. Pour the slurry out of the ball mill jar and pass the slurry through a 100-mesh sieve until the particle size D50 of the slurry is within the range of 0.2μm. If the requirement is not met, reduce or increase the ball milling time to finally obtain the slurry.

[0042] 3) Slurry classification: The obtained slurry was allowed to stand for 3 minutes, then 1 / 10 of the upper slurry volume was poured off, and the remaining 9 / 10 of the slurry volume was poured back into the ball mill jar and ball milled for 1 hour. After standing for 3 minutes, another 1 / 10 of the upper slurry volume was poured off, and the remaining 9 / 10 of the slurry volume was poured back into the ball mill jar and ball milled for 1 hour. After standing for 3 minutes, another 1 / 10 of the upper slurry volume was poured off, and a suspending agent was added to the remaining slurry. The mixture was stirred for 3 hours to obtain the classified slurry. During the slurry classification process, the particle size of the slurry was controlled to be within the D50 range of 0.2 μm after each ball milling.

[0043] 4) Slurry casting: Pour the graded slurry into the prepared plaster mold. Let the slurry stand for 10 minutes. After 10 minutes, pour out the excess slurry. Place the mold at room temperature for 3 hours to ensure that the support can be demolded and has a certain strength, thus obtaining a wet blank.

[0044] 5) Drying: Place the demolded support into an oven to dry at a temperature of 80℃ for 4 hours at a heating rate of 1℃ / min to obtain a dry blank.

[0045] 6) Sintering: The dried blanks are placed in a kiln for sintering. The heating regime is as follows: first, heat the blanks to 200℃ in 3 hours, then heat the blanks to 1190℃ in 4 hours, and then hold the blanks for 2 hours to obtain a rough ceramic film support.

[0046] 7) Polishing and grinding: The sintered support is placed in a polishing machine for polishing and grinding until it reaches the required size. After subsequent cutting and drying, the ceramic ultrafiltration support is obtained.

[0047] Example 2

[0048] This embodiment provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support, the steps of which are as follows:

[0049] 1) Ingredients: Mix 500g of alumina powder with a particle size D50 of 1μm and a particle size distribution (D90-D10) / D50≤3.0, 50g of kaolin, 35g of magnesium oxide, 4g of sodium carboxymethyl cellulose, 25g of corn starch, 4g of sodium tripolyphosphate, 5g of sodium hexametaphosphate, and 500g of water to obtain the raw and auxiliary materials.

[0050] 2) Wet ball milling of raw materials: Load all the raw and auxiliary materials prepared above into a ball mill jar and add 336.9g, 561.5g and 224.6g of high-alumina ball milling beads with diameters of 5mm, 3mm and 1mm respectively; place the ball mill jar on a roller ball mill, the ball mill speed is 10r / min, and the ball milling time is 12h. Pour the slurry out of the ball mill jar and pass the slurry through a 100-mesh sieve until the particle size D50 of the slurry is in the range of 0.6μm. If the requirement is not met, reduce the ball milling time or increase the ball milling time to finally obtain the slurry.

[0051] 3) Slurry classification: The obtained slurry was allowed to stand for 5 minutes, then 1 / 10 of the upper slurry volume was poured off, and the remaining 9 / 10 of the slurry volume was poured back into the ball mill jar and ball milled for 2 hours. After standing for 5 minutes, another 1 / 10 of the upper slurry volume was poured off, and the remaining 9 / 10 of the slurry volume was poured back into the ball mill jar and ball milled for 2 hours. After standing for 5 minutes, another 1 / 10 of the upper slurry volume was poured off, and a suspending agent was added to the remaining slurry. The mixture was stirred for 8 hours to obtain the classified slurry. During the slurry classification process, the particle size of the slurry was controlled to be within the D50 range of 0.6 μm after each ball milling.

[0052] 4) Slurry casting: Pour the graded slurry into the prepared plaster mold. Let the slurry stand for 20 minutes. After 20 minutes, pour out the excess slurry. Place the mold at room temperature for 12 hours to ensure that the support can be demolded and has a certain strength, thus obtaining a wet blank.

[0053] 5) Drying: Place the demolded support into an oven to dry at a temperature of 80℃ for 6 hours at a heating rate of 1℃ / min to obtain a dry blank.

[0054] 6) Sintering: The dried blanks are placed in a kiln for sintering. The heating regime is as follows: first, the temperature is raised to 200℃ in 4 hours, then raised to 1250℃ in 5 hours, and then held for 3 hours to obtain a rough ceramic film support.

[0055] 7) Polishing and grinding: The sintered support is placed in a polishing machine for polishing and grinding until it reaches the required size. After subsequent cutting and drying, the ceramic ultrafiltration support is obtained.

[0056] Example 3

[0057] This embodiment provides a method for preparing a low-defect, high-precision ceramic ultrafiltration support, the steps of which are as follows:

[0058] 1) Ingredients: Prepare 500g of alumina powder with a particle size D50 of 3μm and a particle size distribution (D90-D10) / D50≤3.0, 100g of kaolin, 50g of sintering aid, 5g of sodium carboxymethyl cellulose, 50g of pore-forming agent, 5g of sodium tripolyphosphate, 15g of sodium hexametaphosphate, and 500g of water. The sintering aid is one or more oxides such as magnesium oxide, yttrium oxide, titanium oxide, and zirconium oxide. The pore-forming agent is one or more of corn starch, tapioca starch, and pea starch.

[0059] 2) Wet ball milling of raw materials: Load all the raw and auxiliary materials prepared above into a ball mill jar, and add 367.5g, 612.55g, and 367.5g of high-alumina ball milling beads with diameters of 5mm, 3mm, and 1mm respectively; place the ball mill jar on a roller ball mill, the ball mill speed is 10r / min, and the ball milling time is 24h. Pour the slurry out of the ball mill jar and pass the slurry through a 100-mesh sieve until the particle size D50 of the slurry is within the range of 1μm. If the requirement is not met, reduce or increase the ball milling time to finally obtain the slurry.

[0060] 3) Slurry classification: Let the obtained slurry stand for 10 minutes, then pour off 1 / 10 of the upper slurry volume, and pour the remaining 9 / 10 of the slurry back into the ball mill jar and ball mill for 3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 of the upper slurry volume again, and pour the remaining 9 / 10 of the slurry back into the ball mill jar and ball mill for 3 hours. Let it stand for 10 minutes, then pour off 1 / 10 of the upper slurry volume again. Add a suspending agent to the remaining slurry and stir for 10 hours to obtain the classified slurry. During the slurry classification process, the particle size of the slurry is controlled to be within the D50 range of 1μm after each ball milling.

[0061] 4) Slurry casting: Pour the graded slurry into the prepared plaster mold. Let the slurry stand for 30 minutes. After 30 minutes, pour out the excess slurry. Place the mold at room temperature for 24 hours to ensure that the support can be demolded and has a certain strength, thus obtaining a wet blank.

[0062] 5) Drying: Place the demolded support into an oven for drying at 80℃ for 8 hours at a heating rate of 1℃ / min to obtain a dry blank.

[0063] 6) Sintering: The dried blanks are placed in a kiln for sintering. The heating regime is as follows: first, heat the blanks to 200℃ in 5 hours, then heat the blanks to 1350℃ in 6 hours, and then hold the blanks for 4 hours to obtain a rough ceramic film support.

[0064] 7) Polishing and grinding: The sintered support is placed in a polishing machine for polishing and grinding until it reaches the required size. After subsequent cutting and drying, the ceramic ultrafiltration support is obtained.

[0065] Example 4

[0066] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is magnesium oxide, and the pore-forming agent is cassava starch.

[0067] Example 5

[0068] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is magnesium oxide, and the pore-forming agent is pea starch.

[0069] Example 6

[0070] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is yttrium oxide, and the pore-forming agent is corn starch.

[0071] Example 7

[0072] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is yttrium oxide, and the pore-forming agent is tapioca starch.

[0073] Example 8

[0074] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is yttrium oxide, and the pore-forming agent is pea starch.

[0075] Example 9

[0076] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is titanium dioxide, and the pore-forming agent is corn starch.

[0077] Example 10

[0078] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is magnesium oxide and titanium oxide, and the pore-forming agent is cassava starch.

[0079] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is titanium dioxide, and the pore-forming agent is one or more types of pea starch.

[0080] Example 12

[0081] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is zirconium oxide, and the pore-forming agent is corn starch.

[0082] Example 13

[0083] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is zirconium oxide, and the pore-forming agent is cassava starch.

[0084] Example 14

[0085] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is zirconium oxide, and the pore-forming agent is pea starch.

[0086] Example 15

[0087] The difference between this embodiment and Embodiment 1 is that the sintering aid used in this embodiment is a mixture of magnesium oxide, yttrium oxide, titanium oxide and zirconium oxide in a mass ratio of 1:1:1:1, and the pore-forming agent is a mixture of corn starch, tapioca starch and pea starch in a mass ratio of 1:1:1:1.

[0088] The ceramic ultrafiltration supports obtained in Examples 1 to 3 were tested. Porosity was measured using a vacuum immersion water method, average pore size was measured using the immersion pressure method, flexural strength was measured using the three-point bending strength method, and pure water flux was measured using the flow rate of pure water passing through at 1 bar. The microstructure of the supports was observed using scanning electron microscopy. The test results are shown in Table 1 and... Figure 1 , 2 As shown in Figure 3:

[0089] Table 1

[0090]

[0091] As shown in Table 1, the ceramic membrane supports prepared in Examples 1-3 have a porosity of over 30%, a flexural strength of over 35 MPa, and a water flux of 0.5 m³ / s. 3 / (m 2The ceramic membrane support, with an average pore size between 0.01 μm and 0.1 μm (*h*bar) and above, is at the ultrafiltration level. The pore size distribution is significantly smaller than 2.5 μm, far exceeding the market average, demonstrating a clear advantage in narrow pore size and low defect rate. Furthermore, the ceramic membrane support of this invention is prepared using a slip casting method, eliminating the need for lubricants such as oleic acid or tung oil. This significantly reduces environmental pollution caused by lubricant discharge during sintering, greatly shortens the debinding time, and improves production efficiency. Therefore, the method of this invention for preparing ceramic membrane supports not only reduces environmental pollution and sintering cycle time but also significantly surpasses existing technologies in performance indicators such as narrow pore size and low defect rate. This has a positive promoting effect on the development of the nanofiltration and molecular sieve-level ceramic membrane industry and is worthy of widespread application.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention. Technologies not described in detail in this invention are known technologies.

Claims

1. A low-defect, high-precision ceramic ultrafiltration support, characterized in that, The ceramic ultrafiltration support comprises the following raw and auxiliary materials in parts by weight: 100 parts alumina powder, 5-20 parts kaolin, 5-10 parts sintering aid, 0.1-1 parts sodium carboxymethyl cellulose, 1-10 parts pore-forming agent, 0.1-1 parts sodium tripolyphosphate, 0.5-3 parts sodium hexametaphosphate, and 100 parts water. The alumina powder has a particle size D50 of 0.5-3 μm and a particle size distribution (D90-D10) / D50 ≤ 3.

0. The sintering aid is one or more of magnesium oxide, yttrium oxide, titanium oxide, and zirconium oxide; The pore-forming agent is one or more of corn starch, tapioca starch, and pea starch; The preparation method of the low-defect, high-precision ceramic ultrafiltration support includes the following steps: 1) Ingredients: Weigh alumina powder, kaolin, sintering aid, sodium carboxymethyl cellulose, pore-forming agent, sodium tripolyphosphate, sodium hexametaphosphate and water respectively, mix them to obtain raw and auxiliary materials; 2) Wet ball milling of raw materials: All raw and auxiliary materials are loaded into a ball mill jar, and then the ball mill jar is placed in a roller ball mill for ball milling. Then the mixture is passed through a 100-mesh sieve until the particle size D50 of the slurry is in the range of 0.2-1μm to obtain the slurry. 3) Slurry classification: Let the obtained slurry stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry, and pour the remaining 9 / 10 volume of slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry again, and pour the remaining 9 / 10 volume of slurry back into the ball mill jar and ball mill for 1-3 hours. Let it stand for 3-10 minutes, then pour off 1 / 10 volume of the upper slurry again. Add a suspending agent to the remaining slurry and stir for 3-10 hours to obtain the classified slurry. During the slurry classification process, after each ball milling, control the slurry particle size to be within the D50 range of 0.2-1μm. 4) Slurry casting: Pour the graded slurry into the plaster mold, let the slurry stand for 10-30 minutes, then pour out the excess slurry, and place the mold at room temperature for 3-24 hours to obtain a wet blank; 5) Drying: Place the demolded support in an oven to dry, obtaining a dry blank; 6) Sintering: The dried blanks are placed in a kiln and sintered at high temperature, and then cooled naturally to obtain a rough ceramic film support. 7) Polishing and grinding: The rough ceramic membrane support is placed in a polishing machine for polishing and grinding, then cut, and dried again to obtain the ceramic ultrafiltration support; The heating regime for high-temperature sintering described in step 6) is as follows: first, heat to 200℃ in 3-5 hours, then heat to 1190-1350℃ in 4-6 hours, and then hold at that temperature for 2-4 hours.

2. The low-defect, high-precision ceramic ultrafiltration support as described in claim 1, characterized in that, In the ball milling process described in step 2), the mass ratio of raw materials and grinding balls is 1:

1. High alumina grinding balls with diameters of 5mm, 3mm, and 1mm are selected. The mass ratio of high alumina grinding balls with diameters of 5mm, 3mm, and 1mm is 3:5:

2. The ball mill speed is 10r / min, and the ball milling time is 8-24h.

3. The low-defect, high-precision ceramic ultrafiltration support as described in claim 2, characterized in that, The mass ratio of alumina powder to suspending agent in step 3) is 100:0.1-5.

4. The low-defect, high-precision ceramic ultrafiltration support as described in claim 3, characterized in that, The drying temperature described in step 5) is 80℃, the drying time is 4-8h, and the drying heating rate is 1℃ / min.

Images