A filter material and a method for producing the same

Abstract

The application discloses a filter core material and a preparation method thereof, and belongs to the technical field of water purification filter cores. The filter core material comprises the following components in percentage by mass: a honeycomb support matrix: 15-60%; a filter substrate: 30-40%; and a coating substrate: 0-50%. The filter core material and the preparation method thereof maintain a stable support structure during the preparation of a gamma-Al2O3 / BN composite ceramic layer through polypropylene and cellulose nanofiber. The filter substrate is obtained through gradient low-temperature sintering, effectively removes small particles and pollutants in water, and has excellent filtering performance. The active carbon fiber and polyether sulfone are coated on the filter substrate through electrospinning, which ensures good filtering performance and water permeability, improves the wear resistance and compressive strength of the filter core, and removes the honeycomb support matrix through high-temperature combustion, further improves the water permeability, and the active carbon fiber is physically activated during the combustion process, further improving the adsorption capacity.

Description

Technical Field

[0001] This invention relates to the field of water purification filter technology, specifically to a filter material and its preparation method. Background Technology

[0002] The filter element is the main component in a filter that plays a filtering role. The filter element removes a small amount of solid particles from the liquid, which can protect the normal operation of the equipment or ensure the cleanliness of the air. When the fluid enters the filter element containing a filter screen of a certain size, the impurities are blocked, while the clean fluid flows out through the filter element.

[0003] Currently available filter materials on the market are insufficient in terms of water permeability and filtration efficiency, making it difficult to meet the needs of specific application scenarios. For example, activated carbon and ceramic filter elements have good water permeability but low filtration efficiency; while reverse osmosis membranes and nanofiltration membranes have high filtration efficiency but poor water permeability and are prone to clogging. Furthermore, they require regular replacement with each use, resulting in a low reuse rate. Therefore, this paper proposes a filter material and its preparation method that achieves high filtration efficiency and high water permeability while also offering the advantage of convenient reuse. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a filter element material and its preparation method, which solves the problems that existing filter elements cannot simultaneously maintain high filtration efficiency and high water permeability, and have a low reusability rate.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a filter element material, the components of which, by mass percentage, comprise:

[0006] Cellular support substrate: 15%–60%;

[0007] Filter substrate: 30%–40%;

[0008] Coating substrate: 0-50%.

[0009] The present invention is further configured such that: the honeycomb support matrix is ​​made of polypropylene and cellulose nanofibers by 3D printing, wherein the polypropylene and cellulose nanofibers comprise, by weight ratio: 16-19:0.5-1.2.

[0010] Cellulose nanofibers are unmodified cellulose nanofibers with less than 1% lignin residue. Polypropylene and cellulose nanofibers produce water and carbon dioxide upon combustion. The cellulose molecular chain (C6H...) contains... 10 O5)n is completely oxidized under oxygen-rich conditions at 500℃:

[0011] C6H 10 O5 + 6O2 → 6CO2 + 5H2O

[0012] The application is further provided: the filter substrate comprises nano-aluminum oxide and boron nitride nanosheet, wherein the nano-aluminum oxide and boron nitride nanosheet comprise 7-12:0.7-1.1 by weight ratio.

[0013] The application is further provided: the coating substrate comprises activated carbon fiber and polyether sulfone, wherein the activated carbon fiber and polyether sulfone comprise 0.8-1.3:8-12 by weight ratio.

[0014] The application also discloses a preparation method of the filter core material, specifically comprising the following steps:

[0015] Step one, uniformly mix polypropylene and cellulose nanofiber according to a weight ratio of 16-19:0.5-1.2, 3D print into a honeycomb structure, and obtain a honeycomb support matrix;

[0016] Step two, immerse the honeycomb support matrix in boron nitride nanosheet alumina sol, vertically pull at a speed of 0.3-0.6 m / min, repeat 3 times to form a uniform coating, then perform gradient low-temperature sintering to obtain a gamma-Al2O3 / BN composite ceramic layer as a filter substrate;

[0017] Step three, uniformly mix activated carbon fiber and polyether sulfone according to a weight ratio of 0.8-1.3:8-12, load into a spinning machine, form a fiber membrane with a thickness of 45-55 μm on the surface of the gamma-Al2O3 / BN composite ceramic layer under a voltage of 20 kV and a receiving distance of 15 cm, and obtain a composite filter core.

[0018] The application is further provided: the pore size of the honeycomb structure in step one is 1-3 mm, and the wall thickness is 0.3-0.5 mm.

[0019] The application is further provided: the gradient low-temperature sintering mode in step two comprises:

[0020] heat the sintering furnace to 80-120 DEG C and keep the temperature for 45-60 min, and dry and solidify the boron nitride nanosheet alumina sol coating;

[0021] heat the sintering furnace to 150-180 DEG C and keep the temperature for 60-90 min, so that the dry and solidified boron nitride nanosheet alumina sol coating is preliminarily sintered into a ceramic layer;

[0022] heat the sintering furnace to 200-220 DEG C and keep the temperature for 120-180 min, so that the ceramic layer is densified.

[0023] The application is further provided with: further comprising placing the composite filter element in a muffle furnace, heating to 380-400 DEG C at 10 DEG C / min, taking out after keeping warm for 25-45 min, cooling to room temperature, flushing with 0.3-0.5 MPa compressed air, and obtaining the regenerated water-permeable filter element.

[0024] The application provides a filter element material and a preparation method thereof.

[0025] (1) The application can effectively remove the small particles and pollutants in water, has excellent filtering performance, and can improve the wear resistance and compressive strength of the filter element by coating the activated carbon fiber and polyether sulfone on the filter substrate through electrospinning, and can further improve the water permeability by removing the honeycomb support substrate through high-temperature combustion, and the activated carbon fiber is physically activated during the combustion process, further improving the adsorption capacity.

[0026] (2) The application can also clean the impurities of the regenerated water-permeable filter element by high-temperature combustion to realize secondary utilization, has the advantages of high reuse rate and clean convenience. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the application will be described below in a clear and complete manner. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0028] Embodiment one

[0029] A preparation method of a filter element material, specifically comprising the following steps:

[0030] Step one, uniformly mix polypropylene and cellulose nanofiber according to a weight ratio of 16:1.2, 3D print into a honeycomb structure with a pore diameter of 2 mm and a wall thickness of 0.4 mm, and obtain a honeycomb support substrate, the mass fraction of the honeycomb support substrate in the filter element material is 20%, which is used to provide structural strength and support, and ensure that the filter element does not deform under high pressure or complex working conditions;

[0031] Step two, after mixing the nano-alumina and boron nitride nanosheet uniformly according to a weight ratio of 7:1.1, an alumina sol containing boron nitride nanosheet is obtained, the honeycomb support substrate is immersed in the alumina sol containing boron nitride nanosheet, and is vertically lifted at a speed of 0.3 m / min, and after repeating the process 3 times to form a uniform coating, the coating is placed in a sintering furnace, the sintering furnace is heated to 95℃, and is kept for 55 min, so that the alumina sol coating containing boron nitride nanosheet is dried and solidified;

[0032] The sintering furnace is heated to 160℃, and is kept for 80 min, so that the dried and solidified alumina sol coating containing boron nitride nanosheet is preliminarily sintered into a ceramic layer;

[0033] The sintering furnace is heated to 210℃, and is kept for 150 min, so that the ceramic layer is densified, and a γ-Al2O3 / BN composite ceramic layer is obtained, which is used as a filter substrate, and the mass ratio of the filter substrate in the filter core material is 30%, which is used as the core part of the filter core material and is responsible for intercepting pollutants, so as to ensure sufficient filtration area and filtration precision, while balancing the air permeability and filtration efficiency of the material, wherein the thickness of the γ-Al2O3 / BN composite ceramic layer is 53μm;

[0034] Step three, after mixing the activated carbon fiber and polyether sulfone uniformly according to a weight ratio of 0.8:12, the mixture is loaded into a spinning machine, and a fiber membrane with a thickness of 45μm is formed on the surface of the γ-Al2O3 / BN composite ceramic layer under the condition of a voltage of 20kV and a receiving distance of 15cm, which is used as a coating substrate, and the mass ratio of the coating substrate in the filter core material is 50%, which is used to protect the filter substrate and prevent the material from falling off or being damaged, and further improve the adsorption capacity, and a composite filter core is obtained.

[0035] The filter core obtained in the embodiment is composed of a honeycomb support substrate, a filter substrate and a coating substrate.

[0036] Example two

[0037] A preparation method of a filter core material, specifically comprising the following steps:

[0038] Step one, after mixing polypropylene and cellulose nanofiber uniformly according to a weight ratio of 18:0.9, a honeycomb structure with a pore diameter of 3mm and a wall thickness of 0.3mm is 3D printed to obtain a honeycomb support substrate, and the mass ratio of the honeycomb support substrate in the filter core material is 15%;

[0039] Step two, after mixing the nano-alumina and boron nitride nanosheet uniformly in a weight ratio of 9:1, an alumina sol containing boron nitride nanosheet is obtained, the honeycomb support matrix is immersed in the alumina sol containing boron nitride nanosheet, and is vertically lifted at a speed of 0.5 m / min, and after repeating 3 times to form a uniform coating, it is placed in a sintering furnace, the sintering furnace is heated to 95℃, and is kept for 55 min, so that the alumina sol containing boron nitride nanosheet coating is dried and solidified;

[0040] The sintering furnace is heated to 160℃, and is kept for 80 min, so that the dried and solidified alumina sol containing boron nitride nanosheet coating is preliminarily sintered into a ceramic layer;

[0041] The sintering furnace is heated to 210℃, and is kept for 150 min, so that the ceramic layer is densified, and a γ-Al2O3 / BN composite ceramic layer is obtained as a filter substrate, the mass ratio of the filter substrate in the filter core material is 35%, and the thickness of the γ-Al2O3 / BN composite ceramic layer is 55μm;

[0042] Step three, after mixing the activated carbon fiber and polyether sulfone uniformly in a weight ratio of 1.2:9, the mixture is loaded into a spinning machine, and a fiber membrane with a thickness of 55μm is formed on the surface of the γ-Al2O3 / BN composite ceramic layer under the environment of a voltage of 20kV and a receiving distance of 15cm, as a coating substrate, the mass ratio of the coating substrate in the filter core material is 50%, and a composite filter core is obtained;

[0043] Step four, the composite filter core is placed in a muffle furnace, heated to 385℃ at a rate of 10℃ / min, kept for 45 min, then taken out and cooled to room temperature, and washed with compressed air at a pressure of 0.5MPa, to obtain a regenerated water-permeable filter core.

[0044] The filter core obtained in the embodiment is composed of a filter substrate and a coating substrate.

[0045] Example three

[0046] A preparation method of a filter core material, specifically comprising the following steps:

[0047] Step one, after mixing polypropylene and cellulose nanofiber uniformly in a weight ratio of 19:0.5, a honeycomb structure with a pore diameter of 1mm and a wall thickness of 0.3mm is 3D printed to obtain a honeycomb support matrix, and the mass ratio of the honeycomb support matrix in the filter core material is 60%;

[0048] Step two, after mixing the nano-alumina and boron nitride nanosheet uniformly according to a weight ratio of 12:0.7, an alumina sol containing boron nitride nanosheet is obtained, the honeycomb support substrate is immersed in the alumina sol containing boron nitride nanosheet, and is vertically lifted at a speed of 0.6 m / min, and after repeating the process for 3 times to form a uniform coating, the coating is placed in a sintering furnace, the sintering furnace is heated to 95℃, and is kept for 55 min, so that the alumina sol containing boron nitride nanosheet coating is dried and solidified;

[0049] The sintering furnace is heated to 160℃, and is kept for 80 min, so that the dried and solidified alumina sol containing boron nitride nanosheet coating is preliminarily sintered into a ceramic layer;

[0050] The sintering furnace is heated to 210℃, and is kept for 150 min, so that the ceramic layer is densified, and a γ-Al2O3 / BN composite ceramic layer is obtained as a filter substrate, the mass ratio of the filter substrate in the filter core material is 40%, and the thickness of the γ-Al2O3 / BN composite ceramic layer is 64 μm.

[0051] The filter core obtained in the embodiment is composed of the honeycomb support substrate and the filter substrate.

[0052] Example four

[0053] The embodiment further includes the following steps on the basis of example three.

[0054] Step three, the honeycomb support substrate coated with the filter substrate is placed in a muffle furnace, and is heated to 396℃ at a rate of 10℃ / min, and is kept for 25 min, and then is taken out and cooled to room temperature, and is flushed with compressed air at a pressure of 0.3 MPa, and a regenerated water-permeable filter core is obtained.

[0055] The filter core obtained in the embodiment is composed of the filter substrate.

[0056] For the above-mentioned example one, example two, example three and example four, the regeneration conditions for obtaining the filter core are as follows: the water permeation rate reduction rate of the filter core is monitored, and when the water permeation rate reduction rate is greater than or equal to 15%, the regeneration treatment is needed, and the specific regeneration treatment method includes:

[0057] The filter core is placed in a muffle furnace, and is heated to 500℃ at a rate of 10℃ / min, and is kept for 35 min, and then is taken out and cooled to room temperature, and is flushed with compressed air at a pressure of 0.5 MPa, and a regenerated water-permeable filter core is obtained.

[0058] As a detailed description, when the activated carbon fiber is burned at 400℃, physical activation occurs, the specific surface area increases from 800 m² / g to 1200 m² / g, and the subsequent adsorption performance is enhanced.

[0059] After repeated tests, it is found that the filter cartridges prepared in Example One, Example Two, Example Three and Example Four can be regenerated at least 5 times, wherein the judgment method for qualified filter cartridges is as follows:

[0060] The water permeability is greater than or equal to 90%, the pore structure integrity is analyzed by X-ray tomography, and the pore deformation rate is less than or equal to 5% for qualified filter cartridges.

[0061] Comparative experiment

[0062] According to the preparation method provided in the above-mentioned Example One, Example Two, Example Three and Example Four, filter cartridge One, filter cartridge Two, filter cartridge Three and filter cartridge Four are respectively obtained, and the water permeability rate test is performed on the reverse osmosis membrane filter cartridge and the nanofiltration membrane filter cartridge, and the test results are shown in Table 1:

[0063] Water permeation rate L / (m2·h·bar) Compressive strength (MPa) Filter element one 185 75 Filter element two 478 68 Filter element three 250 55 Filter element four 520 35 Reverse osmosis membrane filter element 35 63 Nanofiltration membrane filter element 52 40

[0064] Table 1

[0065] As can be seen from Table 1, the water permeability rate of the filter cartridge provided by the present application is better than that of the reverse osmosis membrane filter cartridge and the nanofiltration membrane filter cartridge, and the water permeability rate and the compression strength of filter cartridge One and filter cartridge Two are better than those of the reverse osmosis membrane filter cartridge and the nanofiltration membrane filter cartridge, wherein filter cartridge Two is the optimal embodiment.

[0066] Further, according to the filter cartridges prepared in the above-mentioned embodiments, the void connectivity rate is greater than or equal to 90%, and the water permeation pressure difference is less than or equal to 20 MPa, wherein the inner layer pore size of filter cartridge Two is 3 μm, and the outer layer pore size is 76 μm.

[0067] When the water permeability rate of filter cartridge One, filter cartridge Two, filter cartridge Three and filter cartridge Four decreases by greater than or equal to 15%, the filter cartridges are regenerated to obtain regenerated filter cartridge One, regenerated filter cartridge Two, regenerated filter cartridge Three and regenerated filter cartridge Four, and then the water permeability rate is detected according to the ISO 10545-3 standard, and the compression strength is detected according to the GB / T 1964-2020 standard, and the detection results are shown in Table 2:

[0068] Water permeation rate L / (m2·h·bar) Compressive strength (MPa) Regenerated filter element one 476 68 Regenerated filter element two 473 67 Regenerated filter element three 518 35 Regenerated filter element four 513 35

[0069] Table 2

[0070] As can be seen from Table 2, the water permeation speed and the compressive strength of the filter core prepared according to the preparation method provided in Example 1 and Example 2 are similar, and the water permeation speed and the compressive strength of the filter core prepared according to the preparation method provided in Example 3 and Example 4 are similar, that is, after the regeneration treatment, the honeycomb support matrix is eliminated, the compressive strength is reduced, and the water permeation speed is improved, according to the characteristics, the filter core 1, the filter core 2, the filter core 3 and the filter core 4 can be used in different use environments, and after the regeneration treatment, they can be used again by switching the use environment.

[0071] In summary, the filter core material provided by the application has the advantages of high filtration efficiency and high water permeability, and is renewable, low in maintenance cost, and can be effectively applied to a sterile filtration system and treatment of wastewater containing strongly corrosive particles.

[0072] Although the embodiments of the application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A filter element material, characterized in that: Its components, by mass percentage, include: Cellular support substrate: 15%–60%; Filter substrate: 30%–40%; Coating substrate: 0-50%; The honeycomb support matrix is ​​made of polypropylene and cellulose nanofibers; The filter substrate is obtained by gradient low-temperature sintering, specifically: the sintering furnace is heated to 80-120℃ and held for 45-60 minutes to dry and solidify the boron nitride nanosheet alumina sol coating; the sintering furnace is heated to 150-180℃ and held for 60-90 minutes to preliminarily sinter the dried and solidified boron nitride nanosheet alumina sol coating into a ceramic layer; the sintering furnace is heated to 200-220℃ and held for 120-180 minutes to densify the ceramic layer.

2. The filter material according to claim 1, characterized in that: The honeycomb support matrix is ​​manufactured by 3D printing, wherein the polypropylene and cellulose nanofibers are in a weight ratio of 16-19:0.5-1.

2.

3. A filter element material according to claim 1 or 2, characterized in that: The filter substrate comprises nano-alumina and boron nitride nanosheets, wherein the nano-alumina and boron nitride nanosheets comprise, by weight ratio, 7-12:0.7-1.

1.

4. A filter material according to claim 1 or 2, characterized in that: The coating substrate includes activated carbon fiber and polyethersulfone, wherein the activated carbon fiber and polyethersulfone are in a weight ratio of 0.8-1.3:8-12.

5. A method for preparing the filter material according to any one of claims 1-4, characterized in that: Specifically, the following steps are included: Step 1: Mix polypropylene and cellulose nanofibers at a ratio of 16-19: After being mixed evenly at a weight ratio of 0.5-1.2, the mixture is 3D printed into a honeycomb structure to obtain the honeycomb support matrix; Step 2: Immerse the honeycomb support substrate in boron nitride nanosheet alumina sol, and vertically pull it at a speed of 0.3-0.6 m / min. Repeat this process 3 times to form a uniform coating. Then, perform gradient low-temperature sintering to obtain a γ-Al2O3 / BN composite ceramic layer as a filter substrate. Step 3: Mix activated carbon fiber and polyethersulfone evenly at a weight ratio of 0.8-1.3:8-12, load them into a spinning machine, and form a fiber membrane with a thickness of 45-55μm on the surface of the γ-Al2O3 / BN composite ceramic layer under an environment of 20kV voltage and a receiving distance of 15cm to obtain a composite filter element.

6. The method for preparing a filter element material according to claim 5, characterized in that: In step one, the pore size of the honeycomb structure is 1-3 mm, and the wall thickness is 0.3-0.5 mm.

7. A method for preparing a filter element material according to claim 5 or 6, characterized in that: The process also includes placing the composite filter element in a muffle furnace, heating it to 380-400℃ at a rate of 10℃ / min, holding it at that temperature for 25-45 minutes, removing it and cooling it to room temperature, and then rinsing it with compressed air at 0.3-0.5MPa to obtain a regenerated water-permeable filter element.