Preparation method of high-precision multichannel tubular composite ceramic membrane

Abstract

The invention discloses a preparation method of a high-precision multi-channel tubular composite ceramic membrane. The preparation method comprises the following steps: step 1, preparing raw materials; step 2, preparing a polyacrylate-aluminum oxide compound; step 3, preparing coating slurry; according to the method, the membrane layer integrity of the multi-channel tubular ceramic membrane is improved, and the pore size distribution of the multi-channel tubular ceramic membrane is more concentrated. Due to concentration and reduction of the aperture, the multi-channel tubular composite ceramic membrane shows higher selectivity and rejection rate when filtering particles, which is particularly important for application occasions requiring high-precision filtration. In addition, the smooth surface of the membrane and the integrity of the membrane layer reduce the attachment of pollutants, so that the service life of the ceramic membrane is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of ceramic membrane preparation, and in particular relates to a method for preparing a high-precision multi-channel tubular composite ceramic membrane. Background Art

[0002] The demand for efficient and stable separation technologies is growing in fields such as chemistry, pharmaceuticals, food and beverages, agricultural products, and biofermentation. Multichannel tubular ceramic membranes, due to their exceptional mechanical strength, excellent filtration performance, and anti-fouling properties, hold great promise for application in these fields. In industrial separation, wastewater treatment, and deep water purification, multichannel tubular ceramic membranes offer a significantly improved filtration efficiency compared to single-channel membranes due to their tubular structure, while maintaining the membrane's mechanical strength while increasing the contact area with the liquid. This significantly reduces the production and operating costs of the membrane. However, coating multichannel tubular ceramic membranes with conventional single-channel ceramic membrane coating methods and materials often results in incomplete or cracked membranes. This is because the smaller inner diameter of the multichannels makes conventional slurries less likely to form films on the inner walls of the multichannels, which can easily lead to membrane defects. Therefore, the development of multichannel tubular ceramic membranes with qualified pore sizes, uniform, and complete membranes has become an urgent challenge.

[0003] For example, Chinese patent publication number CN117945512A proposes an innovative structural design by disposing multiple filter units and flow-guiding units within a support body. The filter units comprise a filter channel, a transition layer, and a membrane layer, with the transition layer coated on the support body and the membrane layer coated on the transition layer. The flow-guiding units comprise a flow-guiding channel, end seals, and perforations. This design allows a portion of the permeate to seep out of the sidewalls of the support body, while the remaining portion is collected in the flow-guiding channel and discharged through the perforations. This reduces the distance the permeate travels within the support body, thereby improving the filtration efficiency of the filter units, particularly the central and inner filter units. Furthermore, this design improves wall thickness effects, shielding effects, and interference effects. Despite this, the patent still uses a conventional coating slurry, which cannot ensure the uniformity and integrity of the membrane layer. For example, Chinese patent publication number CN117945512A relates to a method for preparing an electrochemical tubular ceramic membrane. This method involves ultrasonically cleaning and drying the tubular ceramic membrane substrate, followed by sequential deposition of a titanium conductive layer and a ruthenium-iridium active layer in an argon atmosphere. The active layer is prepared using magnetron sputtering technology, making the film more dense and uniform. Although this method improves the integrity of the film, its implementation is complicated and leads to increased costs, making it unsuitable for subsequent large-scale production.

[0004] In view of this, it is particularly important to develop a multi-channel tubular ceramic membrane with a complete membrane layer, a concentrated pore size distribution and an adjustable pore size. This patent proposes an innovative method by compounding polyacrylate with alumina powder to prepare a slurry, thereby simply preparing a multi-channel tubular ceramic membrane with a complete membrane layer, a concentrated pore size distribution and an adjustable pore size. This method not only improves the uniformity of the membrane layer and the consistency of the pore size, but also can flexibly control the pore size by adjusting the formula ratio to meet the needs of different application fields. For example, in the field of water treatment, by optimizing the pore size, the filtration efficiency can be effectively improved while ensuring the filtration accuracy, which is of great significance for improving the recycling rate of water resources. Summary of the Invention

[0005] In view of the defects and shortcomings of the existing process, the purpose of the present invention is to provide a high-precision multi-channel tubular composite ceramic membrane preparation method, which aims to flexibly control the pore size to meet the needs of different application fields.

[0006] In order to achieve the above technical objectives, the present invention provides a method for preparing a high-precision multi-channel tubular composite ceramic membrane, comprising the following steps:

[0007] Step 1: Prepare raw materials: polyacrylate emulsion, Al2O3 powder, polyvinyl pyrrolidone (PVP), ethanol, methanol, toluene solution, hydroxypropyl methylcellulose (HPMC), binder, pure water, and multi-channel ceramic support;

[0008] Step 2: Preparation of polyacrylate-alumina complex: A certain amount of alumina powder was added to a 1000ml four-necked flask equipped with a stirrer, a reflux condenser, a constant pressure dropping funnel, and a thermometer; then, a butyl acrylate-methyl methacrylate copolymer emulsion was added, followed by an ethanol solution containing PVP; vacuum was evacuated and N2 was passed through, and this process was repeated three times; the stirrer was started and the temperature in the flask was heated to 70°C. At this temperature, a toluene solution was added dropwise from the constant pressure dropping funnel, and the temperature was completed in about half an hour. The temperature was then raised to 85°C for a period of time. After the reaction was completed, stirring was continued for 1 hour, and the mixture was cooled. An appropriate amount of methanol was added to the solution in the four-necked flask and the mixture was centrifuged at 10,000 rpm for 1 hour. The solid obtained by centrifugation was dried at 80°C for 12 hours. The dried solid was then ball-milled in a ball mill for 12 hours to obtain an alumina powder complex coated with polyacrylate.

[0009] Step 3: Preparation of coating slurry: Mix polyacrylate-alumina composite, HPMC, binder, dispersant, and pure water in a certain proportion, heat and stir, and ultrasonicate in an ultrasonic device for 1 hour to form a stable coating liquid with good film-forming properties;

[0010] Step 4: Preparation of multi-channel tubular ceramic membrane: Use dipping equipment to dip-coat the coating slurry on the multi-channel tubular ceramic membrane, dry it at 80℃, place it in a high-temperature sintering furnace for high-temperature sintering, and after cooling, obtain a multi-channel tubular composite ceramic membrane with a complete membrane layer, smooth membrane surface and narrow pore size distribution.

[0011] Preferably, the polyacrylate emulsion in step 1 includes the following components: such as butyl acrylate and methyl methacrylate copolymer emulsion.

[0012] Preferably, the binder in step 1 includes the following components: cellulose, starch and water-soluble polymer.

[0013] Preferably, in step 3, the ratio of polyacrylate-alumina composite, HPMC, binder, dispersant and water is 5-10:0.5:2:2:100.

[0014] Preferably, the sintering temperature in step 4 is in the range of 1000° C. to 1300° C., and the sintering time is 1 to 3 hours.

[0015] Compared with the existing technology, the technical solution of the present invention brings the following beneficial technical effects:

[0016] This improvement in the present application not only improves the membrane integrity of the multi-channel tubular ceramic membrane, but also makes its pore size distribution more concentrated. Due to the concentration and reduction of the pore size, the multi-channel tubular composite ceramic membrane exhibits higher selectivity and retention rate when filtering particulates, which is particularly important for applications requiring high-precision filtration. In addition, the smoothness of the membrane surface and the integrity of the membrane layer reduce the adhesion of pollutants, thereby extending the service life of the ceramic membrane and reducing maintenance costs. Therefore, the application of polyacrylate-alumina composite not only optimizes the performance of the multi-channel tubular ceramic membrane, but also provides a new solution for industrial filtration and separation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a line graph of the test data of the composite ceramic membrane prepared in Example 1;

[0018] Figure 2 is a line graph of the test data of the composite ceramic membrane prepared in Example 2;

[0019] Figure 3 Schematic diagram of the cross section of a multi-channel tubular ceramic membrane using ordinary slurry;

[0020] Figure 4 Schematic diagram of the cross section of a multi-channel tubular ceramic membrane using a polyacrylate-alumina composite as the dipping slurry. DETAILED DESCRIPTION

[0021] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0022] Example 1

[0023] To a 1000ml four-necked flask equipped with a stirrer, reflux condenser, constant pressure dropping funnel, and thermometer, add 100g of 1μm alumina powder; then add 50ml of butyl acrylate-methyl methacrylate copolymer emulsion, followed by 10ml of ethanol solution containing 2g of PVP; evacuate and vent with nitrogen, repeat three times; start the stirrer and heat the flask to 70°C. At this temperature, add 10ml of toluene solution dropwise from the constant pressure dropping funnel over about half an hour. The temperature is then raised to 85°C for half an hour. After the reaction is complete, continue stirring for another hour and cool. Add 10ml of methanol solution to the solution in the four-necked flask, centrifuge the mixture at 10,000 rpm for 1 hour, and dry the resulting solid at 80°C for 12 hours. The dried solid is then ball-milled for 12 hours to obtain an alumina composite powder coated with polyacrylate. 100g of polyacrylate-1μm alumina composite, 5g of HPMC, 20g of binder, 20g of dispersant, and 1000g of pure water were mixed, heated and stirred, and ultrasonicated for 1 hour to form a stable, well-film-forming coating solution. The outer surface of a 1.5μm multichannel ceramic support was sealed with tape, and the evenly mixed coating slurry was poured into the liquid tank of a dipping device. The multichannel support was dip-coated for 10 seconds using the dipping device to obtain a multichannel ceramic membrane with the coating slurry coated on the inner surface. The ceramic membrane was removed, dried at 80°C for 180 minutes, placed in a high-temperature sintering furnace at 1100°C for 2 hours, and cooled to room temperature to obtain a multichannel tubular composite ceramic membrane with a complete 500nm membrane layer, a smooth membrane surface, and a narrow pore size distribution.

[0024] Example 2

[0025] To a 1000ml four-necked flask equipped with a stirrer, reflux condenser, constant pressure dropping funnel, and thermometer, add 100g of 0.2μm alumina powder; then add 50ml of butyl acrylate-methyl methacrylate copolymer emulsion, followed by 10ml of ethanol solution containing 2g of PVP; evacuate and vent with nitrogen (N2) three times; start the stirrer and heat the flask to 70°C. At this temperature, add 10ml of toluene solution dropwise from the constant pressure dropping funnel over about half an hour. The temperature is then raised to 85°C for half an hour. After the reaction is complete, continue stirring for another hour and cool. Add 10ml of methanol solution to the solution in the four-necked flask, centrifuge the mixture at 10,000 rpm for 1 hour, and dry the resulting solid at 80°C for 12 hours. The dried solid is then ball-milled for 12 hours to obtain an alumina composite powder coated with polyacrylate. 80g of polyacrylate-0.2μm alumina composite, 5g of HPMC, 20g of binder, 20g of dispersant, and 1000g of pure water were mixed, heated and stirred, and ultrasonicated for 1 hour to form a stable, well-film-forming coating solution. The outer surface of a 0.5μm multichannel ceramic support was sealed with tape, and the evenly mixed coating slurry was poured into the liquid tank of a dipping device. The multichannel support was dip-coated for 5 seconds using the dipping device to obtain a multichannel ceramic membrane with the coating slurry coated on the inner surface. The ceramic membrane was removed, dried at 80°C for 180 minutes, placed in a high-temperature sintering furnace at 1000°C for 2 hours, and cooled to room temperature to obtain a multichannel tubular composite ceramic membrane with a complete 100nm membrane layer, a smooth membrane surface, and a narrow pore size distribution.

[0026] like Figure 1 、 2 As shown, two multi-channel tubular composite ceramic membranes prepared in Example 1 and Example 2 were respectively selected for pore size testing, and two multi-channel ceramic membranes dip-coated with ordinary alumina slurry of the same particle size that had not been composited and synthesized on the same support were selected for pore size testing. The pore size was measured using an isopropyl alcohol bubble pressure method pore size tester. Figure 1 、 2 are the test results, a represents an 800nm ​​multi-channel tubular ceramic membrane prepared by dip-coating a common 1μm slurry on a 1.5μm multi-channel tubular support, b represents a 200nm multi-channel tubular ceramic membrane prepared by dip-coating a common 0.2μm slurry on a 0.5μm multi-channel tubular support, c represents a 500nm multi-channel tubular composite ceramic membrane prepared by the method of Example 1, and d represents a 100nm multi-channel tubular composite ceramic membrane prepared by the method of Example 2. Figure 1It can be seen that the multi-channel tubular composite ceramic membrane produced using a polyacrylate-alumina composite as the raw material for the dipping slurry exhibits a significantly more concentrated pore size distribution, a narrower distribution range, and smaller pore sizes than multi-channel tubular ceramic membranes coated with conventional slurries. This is because when the polyacrylate emulsion comes into contact with alumina particles, the polyacrylate molecules' mobility causes the molecular chains to gradually adsorb onto the surface of the alumina particles. As the solvent evaporates or the reaction conditions change, the polyacrylate chains further entangle themselves with the alumina particle surface, thereby encapsulating the alumina. Polyacrylates can form continuous polymer films under certain conditions. In the preparation of ceramic membranes, they can fill the gaps between ceramic particles, interweaving with them to form a continuous whole, improving the density and integrity of the ceramic membrane. This in turn allows for the regulation of the pore size of the ceramic membrane, resulting in a more concentrated pore size distribution and smaller pores.

[0027] like Figure 3 、 4 As shown, the inner wall of the multi-channel tubular ceramic membrane made of the above two slurries is observed. Figure 3 It is a multi-channel tubular ceramic membrane coated with ordinary slurry. Figure 4 A multi-channel tubular composite ceramic membrane made with a polyacrylate-alumina composite as the raw material for the dipping slurry was found to have a smooth surface and an intact membrane layer, while a multi-channel tubular composite ceramic membrane coated with a conventional slurry had a rough surface and an incomplete membrane layer, with some areas of the membrane peeling and causing rupture. This is because polyacrylate can be used as a binder and coating material in the preparation of the composite ceramic membrane. Coating a layer of polyacrylate-alumina composite coating containing functional materials on the ceramic membrane surface not only fixes the functional materials to the ceramic membrane surface through the bonding effect of the polyacrylate, but also protects the functional materials with the thin film formed by the polyacrylate, thereby improving the overall performance of the ceramic membrane.

[0028] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. Any obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a high-precision multi-channel tubular composite ceramic membrane, characterized by: The following steps are involved: Step 1: Prepare raw materials: polyacrylate emulsion, Al2O3 powder, polyvinyl pyrrolidone (PVP), ethanol, methanol, toluene solution, hydroxypropyl methylcellulose (HPMC), binder, pure water, and multi-channel ceramic support; Step 2: Preparation of polyacrylate-alumina complex: A certain amount of alumina powder was added to a 1000ml four-necked flask equipped with a stirrer, a reflux condenser, a constant pressure dropping funnel, and a thermometer; then, a butyl acrylate-methyl methacrylate copolymer emulsion was added, followed by an ethanol solution containing PVP; vacuum was evacuated and N2 was passed through, and this process was repeated three times; the stirrer was started and the temperature in the flask was heated to 70°C. At this temperature, a toluene solution was added dropwise from the constant pressure dropping funnel, and the temperature was completed in about half an hour. The temperature was then raised to 85°C for a period of time. After the reaction was completed, stirring was continued for 1 hour, and the mixture was cooled. An appropriate amount of methanol was added to the solution in the four-necked flask and the mixture was centrifuged at 10,000 rpm for 1 hour. The solid obtained by centrifugation was dried at 80°C for 12 hours. The dried solid was then ball-milled in a ball mill for 12 hours to obtain an alumina powder complex coated with polyacrylate. Step 3: Preparation of coating slurry: Mix polyacrylate-alumina composite, HPMC, binder, dispersant, and pure water in a certain proportion, heat and stir, and ultrasonicate in an ultrasonic device for 1 hour to form a stable coating liquid with good film-forming properties; Step 4: Preparation of multi-channel tubular ceramic membrane: Use dipping equipment to dip-coat the coating slurry on the multi-channel tubular ceramic membrane, dry it at 80℃, place it in a high-temperature sintering furnace for high-temperature sintering, and after cooling, obtain a multi-channel tubular composite ceramic membrane with a complete membrane layer, smooth membrane surface and narrow pore size distribution.

2. The method for preparing a high-precision multi-channel tubular composite ceramic membrane according to claim 1, characterized in that: The polyacrylate emulsion in step 1 includes the following components: such as butyl acrylate and methyl methacrylate copolymer emulsion.

3. The method for preparing a high-precision multi-channel tubular composite ceramic membrane according to claim 1, characterized in that: The binder in step 1 includes the following components: cellulose, starch and water-soluble polymer.

4. The method for preparing a high-precision multi-channel tubular composite ceramic membrane according to claim 1, characterized in that: In step 3, the ratio of the polyacrylate-alumina composite, HPMC, binder, dispersant and water is 5-10:0.5:2:2:

100.

5. The method for preparing a high-precision multi-channel tubular composite ceramic membrane according to claim 1, characterized in that: In step 4, the sintering temperature range is 1000° C.-1300° C.; and the sintering time is 1-3 hours.

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