Ceramic matrix composite activated carbon filter element and preparation method thereof

Abstract

The application relates to the technical field of active carbon materials, and particularly discloses a ceramic-based composite active carbon filter element and a preparation method. The ceramic-based composite active carbon filter element comprises the following raw materials in parts by weight: coated modified active carbon 40-60 parts, carbon nanofiber 1-3 parts, kaolin 5-15 parts, silica sol 12-15 parts, aluminum sol 8-10 parts and pore-forming agent 2-3 parts; the coated modified active carbon is a core-shell material with diatomite loaded nanometer titanium oxide composite material as a shell layer and active carbon as a core. The application can improve the stability of the adsorption efficiency of the ceramic-based composite active carbon filter element under long-term liquid flow impact.

Description

Technical Field

[0001] This invention relates to the technical field of activated carbon materials, and in particular to a ceramic-based composite activated carbon filter element and its preparation method. Background Technology

[0002] With the acceleration of industrialization and urbanization, air and water pollution problems are becoming increasingly prominent. Activated carbon, due to its well-developed pore structure and huge specific surface area, has excellent adsorption performance for pollutants such as volatile organic compounds (VOCs), odor molecules, residual chlorine, and some heavy metal ions, and is widely used in household, commercial, and industrial purification equipment.

[0003] Among related technologies, an arched activated carbon ceramic filter element is disclosed, which is made from the following raw materials in the indicated mass fractions: 40% activated carbon, 30% diatomaceous earth, 20% kaolin, 5% clay, and 5% loess. This product can be used for water filtration to remove residual chlorine from water and improve the taste of the water.

[0004] However, as activated carbon is a dispersed phase encapsulated by the ceramic phase, under long-term liquid flow impact, the water flow will continuously exert shear force and fatigue stress on the internal interface of the material. If the ceramic skeleton is not strong enough, or if there are weaknesses in the interface between the ceramic skeleton and the activated carbon, the water flow will gradually wash the activated carbon particles out of the skeleton, resulting in the loss of activated carbon, which may lead to a decrease in the adsorption efficiency of the filter element. Summary of the Invention

[0005] To improve the stability of the adsorption efficiency of ceramic-based composite activated carbon filter cartridges under long-term liquid flow impact, this application provides a ceramic-based composite activated carbon filter cartridge and its preparation method.

[0006] In the first aspect, the ceramic-based composite activated carbon filter element provided in this application adopts the following technical solution: A ceramic-based composite activated carbon filter element comprises the following raw materials in parts by weight: 40-60 parts of coated modified activated carbon, 1-3 parts of carbon nanofibers, 5-15 parts of kaolin, 12-15 parts of silica sol, 8-10 parts of alumina sol, and 2-3 parts of pore-forming agent; wherein the coated modified activated carbon is a core-shell material with diatomaceous earth-supported nano-titanium oxide composite material as the shell and activated carbon as the core.

[0007] In one specific implementation scheme, the coated modified activated carbon comprises the following raw materials in parts by weight: 100 parts activated carbon, 10-30 parts diatomaceous earth, and 15-45 parts tetrabutyl titanate.

[0008] In one specific feasible implementation, the coated modified activated carbon is prepared according to the following steps: Diatomaceous earth was dispersed in ethanol to obtain a diatomaceous earth dispersion with a mass concentration of 8-10%. Tetrabutyl titanate was added to ethanol and mixed evenly to obtain a tetrabutyl titanate solution with a mass concentration of 8-10%. The diatomaceous earth dispersion was added to the tetrabutyl titanate solution and stirred until homogeneous. Deionized water was added, and the mixture was stirred at 50-60℃ for 2-3 hours. After filtration and drying, diatomaceous earth / Ti(OH)4 powder was obtained. The molar ratio of tetrabutyl titanate to deionized water was 1:(3.9-4.2). Diatomaceous earth / Ti(OH)4 powder was calcined at 280-320℃ for 1-2 hours and then naturally cooled to obtain diatomaceous earth-supported nano-titanium oxide composite material. The diatomaceous earth-supported nano-titanium oxide composite material was dispersed in acidic water and stirred evenly to obtain a sol. Activated carbon is added to the sol and stirred for 3-5 hours under water bath heating at 60-70℃. After filtration and drying, coated modified activated carbon is obtained.

[0009] In one specific implementation, the pH of the acidic water is 1.5-3.0.

[0010] In one specific feasible implementation, the activated carbon has a particle size of 20-40 μm.

[0011] In one specific feasible implementation, the diatomaceous earth has a particle size of 5-15 μm.

[0012] In one specific implementation, the pore-forming agent is porous starch.

[0013] Secondly, this application provides a method for preparing a ceramic-based composite activated carbon filter element, which adopts the following technical solution: A method for preparing a ceramic-based composite activated carbon filter element includes the following steps: According to the formula, after uniformly mixing the coated modified activated carbon, kaolin, carbon nanofibers and pore-forming agent, silica sol and alumina sol are added, deionized water is added, and the mixture is stirred evenly to obtain a paste-like slurry with a solid content between 55% and 65%. Three layers of paste-like slurry are extruded simultaneously and coaxially using a three-layer co-extrusion die to form a green filter element with a gradient structure. After standing at room temperature with a humidity of 90-95% for 12-24 hours and drying, the filter element is heat-treated at 340-360℃ for 2-2.5 hours and then naturally cooled to room temperature to obtain a ceramic-based composite activated carbon filter element.

[0014] In summary, this application has the following beneficial effects: 1. This application, by employing a specific ratio of coated modified activated carbon, carbon nanofibers, kaolin, alumina sol, silica sol, and a preparation method, can improve the initial adsorption rate of ceramic-based composite activated carbon filter cartridges, enhance the stability of adsorption efficiency under long-term liquid flow impact, and reduce the rate of adsorption efficiency reduction.

[0015] 2. In this application, acidic water with a pH of 1.5-3.0, activated carbon with a particle size of 20-40μm, diatomaceous earth with a particle size of 5-15μm, and porous starch are preferably used, which can further improve the stability of the adsorption efficiency of the ceramic-based composite activated carbon filter element under long-term liquid flow impact. Detailed Implementation

[0016] Unless otherwise specified, all raw materials used in this application were obtained commercially. The carbon nanofibers are lignin-based carbon nanofibers, purchased from Chengdu Junxinpeng New Material Technology Co., Ltd. The kaolin, 2000 mesh particle size, was purchased from Shijiazhuang Jinli Mining Co., Ltd. The silica sol, model ZTL-JN, was purchased from Yangzhou Zhongtianli New Material Co., Ltd. The alumina sol, model JL-A1, was purchased from Hangzhou Jiuli Biomaterials Co., Ltd. The activated carbon was purchased from Gongyi Qixin Water Purification Materials Co., Ltd. The diatomaceous earth was purchased from Shandong Xinjiucheng Chemical Technology Co., Ltd. The polyethylene oxide, product number HH91907BGOQV, is from CNOOC Shell.

[0017] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0018] Example Example 1 This embodiment provides a ceramic-based composite activated carbon filter element, comprising the following raw materials: 50 kg of coated modified activated carbon, 2 kg of carbon nanofibers, 10 kg of kaolin, 13.5 kg of silica sol, 9 kg of alumina sol, and 2.5 kg of porous starch.

[0019] Coated modified activated carbon is a core-shell material with diatomaceous earth-supported nano-titanium oxide composite material as the shell and activated carbon as the core.

[0020] The coated and modified activated carbon is prepared according to the following steps: Weigh the following raw materials: 100 kg of activated carbon with a particle size of 20-40 μm, 20 kg of diatomaceous earth with a particle size of 5-15 μm, and 30 kg of tetrabutyl titanate.

[0021] Diatomaceous earth was added to ethanol and dispersed evenly to obtain a diatomaceous earth dispersion with a mass concentration of 9%. Tetrabutyl titanate was added to ethanol and stirred until evenly mixed to obtain a tetrabutyl titanate solution with a mass concentration of 9%.

[0022] Under stirring, the diatomaceous earth dispersion was added dropwise to the tetrabutyl titanate solution. After stirring evenly, deionized water was added according to the molar ratio of tetrabutyl titanate to deionized water of 1:4.05. The mixture was then heated to 55°C in a water bath and stirred at 55°C for 2.5 hours. After filtration, the solid was dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0023] Diatomaceous earth / Ti(OH)4 powder was placed in a calcination furnace and calcined at 300℃ for 1.5 hours. After natural cooling, diatomaceous earth-supported nano-titanium oxide composite material was obtained.

[0024] The diatomaceous earth-supported nano-titanium oxide composite material was dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 2.2 and stirred until homogeneous to obtain a sol.

[0025] Activated carbon was added to the sol, heated to 65°C in a water bath, stirred for 4 hours, filtered, and the solid was dried to obtain coated modified activated carbon.

[0026] This embodiment also provides a method for preparing a ceramic-based composite activated carbon filter element, comprising the following steps: According to the formula, after uniformly mixing the coated modified activated carbon, kaolin, carbon nanofibers and porous starch, silica sol and aluminum sol are added, deionized water is added, and the mixture is stirred evenly to obtain a paste-like slurry with a solid content between 55% and 65%. Three layers of paste-like slurry were extruded simultaneously and coaxially using a three-layer co-extrusion die to form a green filter element with a gradient structure. After standing at room temperature with 95% humidity for 18 hours and drying, the green filter element was placed in a calcination furnace and heat-treated at 350℃ for 2.25 hours. After naturally cooling to room temperature, a ceramic-based composite activated carbon filter element was obtained.

[0027] Example 2 The only difference between this embodiment and Embodiment 1 is that the ceramic-based composite activated carbon filter element includes the following raw materials: 40 kg of coated modified activated carbon, 3 kg of carbon nanofibers, 15 kg of kaolin, 15 kg of silica sol, 10 kg of alumina sol, and 3 kg of porous starch.

[0028] Example 3 The only difference between this embodiment and Embodiment 1 is that the ceramic-based composite activated carbon filter element includes the following raw materials: 60 kg of coated modified activated carbon, 1 kg of carbon nanofibers, 5 kg of kaolin, 12 kg of silica sol, 8 kg of alumina sol, and 2 kg of porous starch.

[0029] Example 4 The only difference between this embodiment and Embodiment 1 is that an equal amount of polyethylene oxide is used to replace the porous starch.

[0030] Example 5 The only difference between this embodiment and Embodiment 1 is that an equal amount of magnesium carbonate is used to replace the porous starch.

[0031] Example 6 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the following raw materials are weighed: 100 kg of activated carbon with a particle size of 20-40 μm, 10 kg of diatomaceous earth with a particle size of 5-15 μm, and 15 kg of tetrabutyl titanate.

[0032] Example 7 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the following raw materials are weighed: 100 kg of activated carbon with a particle size of 20-40 μm, 30 kg of diatomaceous earth with a particle size of 5-15 μm, and 45 kg of tetrabutyl titanate.

[0033] Example 8 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, diatomaceous earth is added to ethanol and dispersed evenly to obtain a diatomaceous earth dispersion with a mass concentration of 8%. Tetrabutyl titanate is added to ethanol and stirred until evenly mixed to obtain a tetrabutyl titanate solution with a mass concentration of 10%.

[0034] Example 9 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, diatomaceous earth is added to ethanol and dispersed evenly to obtain a diatomaceous earth dispersion with a mass concentration of 10%. Tetrabutyl titanate is added to ethanol and stirred until evenly mixed to obtain a tetrabutyl titanate solution with a mass concentration of 8%.

[0035] Example 10 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:3.8. Then, the mixture is heated to 55°C in a water bath and stirred at 55°C for 2.5 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0036] Example 11 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:3.9. Then, the mixture is heated to 55°C in a water bath and stirred at 55°C for 2.5 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0037] Example 12 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:4.2. Then, the mixture is heated to 55°C in a water bath and stirred at 55°C for 2.5 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0038] Example 13 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:4.3. Then, the mixture is heated to 55°C in a water bath and stirred at 55°C for 2.5 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0039] Example 14 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:4.05. Then, the mixture is heated to 50°C in a water bath and stirred at 50°C for 3 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0040] Diatomaceous earth / Ti(OH)4 powder was placed in a calcination furnace and calcined at 280℃ for 2 hours. After natural cooling, diatomaceous earth-supported nano-titanium oxide composite material was obtained.

[0041] The diatomaceous earth-supported nano-titanium oxide composite material was dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 2.2 and stirred until homogeneous to obtain a sol.

[0042] Activated carbon was added to the sol, heated to 60°C in a water bath, stirred for 5 hours, filtered, and the solid was dried to obtain coated modified activated carbon.

[0043] Example 15 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth dispersion is added dropwise to the tetrabutyl titanate solution under stirring. After stirring evenly, deionized water is added according to the molar ratio of tetrabutyl titanate to deionized water of 1:4.05. Then, the mixture is heated to 60°C in a water bath and stirred at 60°C for 2 hours. After filtration, the solid is dried to obtain diatomaceous earth / Ti(OH)4 powder.

[0044] Diatomaceous earth / Ti(OH)4 powder was placed in a calcination furnace and calcined at 320℃ for 1 hour. After natural cooling, diatomaceous earth-supported nano-titanium oxide composite material was obtained.

[0045] The diatomaceous earth-supported nano-titanium oxide composite material was dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 2.2 and stirred until homogeneous to obtain a sol.

[0046] Activated carbon was added to the sol, heated to 70°C in a water bath, stirred for 3 hours, filtered, and the solid was dried to obtain coated modified activated carbon.

[0047] Example 16 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth-supported nano-titanium oxide composite material is dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 1 and stirred evenly to obtain a sol.

[0048] Example 17 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth-supported nano-titanium oxide composite material is dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 1.5 and stirred evenly to obtain a sol.

[0049] Example 18 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth-supported nano-titanium oxide composite material is dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 3.0 and stirred evenly to obtain a sol.

[0050] Example 19 The only difference between this embodiment and Example 1 is that, in the preparation step of the coated modified activated carbon, the diatomaceous earth-supported nano-titanium oxide composite material is dispersed in an acidic dilute hydrochloric acid aqueous solution with a pH of 3.5 and stirred evenly to obtain a sol.

[0051] Example 20 The only difference between this embodiment and Example 1 is that the particle size of the activated carbon is 5-15 μm in the preparation step of the coated modified activated carbon.

[0052] Example 21 The only difference between this embodiment and Example 1 is that the particle size of the activated carbon in the preparation step of the coated modified activated carbon is 50-70 μm.

[0053] Example 22 The only difference between this embodiment and Example 1 is that the particle size of diatomaceous earth is 1-4 μm in the preparation step of the coated modified activated carbon.

[0054] Example 23 The only difference between this embodiment and Example 1 is that the particle size of diatomaceous earth is 20-30 μm in the preparation step of the coated modified activated carbon.

[0055] Example 24 The only difference between this embodiment and Embodiment 1 is that in the preparation method of the ceramic-based composite activated carbon filter element, a three-layer co-extrusion die is used to extrude three layers of paste-like slurry simultaneously and coaxially to form a green filter element with a gradient structure. After standing for 12 hours at room temperature with 90% humidity and drying, the filter element is placed in a calcination furnace and heat-treated at 340°C for 2 hours. After naturally cooling to room temperature, the ceramic-based composite activated carbon filter element is obtained.

[0056] Example 25 The only difference between this embodiment and Embodiment 1 is that, in the preparation method of the ceramic-based composite activated carbon filter element, a three-layer co-extrusion die is used to extrude three layers of paste-like slurry simultaneously and coaxially to form a green filter element with a gradient structure. After standing for 24 hours at room temperature with 93% humidity and drying, the filter element is placed in a calcination furnace and heat-treated at 360°C for 2.5 hours. After naturally cooling to room temperature, the ceramic-based composite activated carbon filter element is obtained.

[0057] Comparative Example Comparative Example 1 The only difference between this comparative example and Example 1 is that, in the raw materials and preparation method of the ceramic-based composite activated carbon filter element, an equal amount of activated carbon is used to replace the coated modified activated carbon.

[0058] Comparative Example 2 The only difference between this comparative example and Example 1 is that, in the raw materials and preparation method of the ceramic-based composite activated carbon filter element, the coated modified activated carbon is replaced with an equal amount of activated carbon and diatomaceous earth mixture in a weight ratio of 1:1.

[0059] Comparative Example 3 The only difference between this comparative example and Example 1 is that an equal amount of coated modified activated carbon is used to replace the carbon nanofibers.

[0060] Comparative Example 4 The only difference between this comparative example and Example 1 is that an equal amount of coated modified activated carbon is used to replace kaolin.

[0061] Comparative Example 5 The only difference between this comparative example and Example 1 is that an equal amount of silica sol is used instead of aluminum sol.

[0062] Comparative Example 6 The only difference between this comparative example and Example 1 is that an equal amount of aluminum sol is used instead of silica sol.

[0063] Performance testing The following performance tests were conducted on Examples 1-25 and Comparative Examples 1-6: A 5 mg / L methylene blue solution was used as the target pollutant aqueous solution. The target pollutant aqueous solution was passed through a ceramic-based composite activated carbon filter at a rate of 1.0 L / min. Samples were taken at the filter outlet at 30 min, 1500 min, and 5000 min after water flow. The concentration of the target pollutant in each sample was determined using a UV spectrophotometer. The adsorption efficiency at 30 min, 1500 min, and 5000 min of liquid flow impact was calculated using the following formula.

[0064] Adsorption efficiency = (Initial methylene blue solution concentration - Methylene blue solution concentration at sampling) / Initial methylene blue solution concentration × 100% The test results are shown in Table 1.

[0065] Table 1 Combining Example 1 and Comparative Examples 1-6 with Table 1, it can be seen that compared to Example 1, the adsorption efficiency of Comparative Examples 1-2 within 30 minutes is significantly lower. Furthermore, the differences between the adsorption efficiencies within 30 minutes, 1500 minutes, and 5000 minutes for Comparative Examples 1-6 are all significantly larger. This indicates that using the raw material ratio and preparation method of Example 1 can improve the initial adsorption rate of the ceramic-based composite activated carbon filter element and enhance the stability of its adsorption efficiency under long-term liquid flow impact, reducing the rate of decrease in adsorption efficiency.

[0066] This is likely because, during the preparation of the coated modified activated carbon, Ti-O-Si covalent bonds are formed between diatomaceous earth and the Ti(OH)4 produced by hydrolysis. After calcination at 300℃, Ti(OH)4 transforms into anatase TiO2, forming diatomaceous earth-loaded TiO2, resulting in a stronger bond. Preparing the diatomaceous earth-loaded TiO2 into an acidic sol allows for the formation of a dense shell of diatomaceous earth / TiO2 on the activated carbon surface in subsequent steps. This shell directly withstands the shear force of the liquid flow, reducing direct scouring and friction on the activated carbon particle surface. Beyond van der Waals forces, a strong mechanical interlocking and chemical adsorption are formed between the shell and the activated carbon core through complex surface chemical interactions, making it extremely difficult for the activated carbon particles to detach from the shell. After uniform dispersion in the slurry, carbon nanofibers interweave to form a three-dimensional network. After the filter element is formed, this network permeates the entire ceramic matrix, preventing cracking and peeling. After co-extruding the three-layer slurry, a gradient structure can be formed by heat treatment at 350℃. The surface layer effectively resists liquid flow impact, protecting the highly adsorbent core layer inside and better preserving adsorption activity. Therefore, this application can improve the stability of the adsorption efficiency of ceramic-based composite activated carbon filter elements under long-term liquid flow impact.

[0067] As can be seen from Examples 1-25 and Table 1, the adsorption efficiency within 30 minutes for all Examples 1-25 is greater than 97%, and the differences between the adsorption efficiencies within 30 minutes, 1500 minutes, and 5000 minutes are all relatively small. This indicates that using the raw material ratios and preparation methods within the range of Examples 1-25 can improve the initial adsorption rate of the ceramic-based composite activated carbon filter element and enhance the stability of its adsorption efficiency under long-term liquid flow impact.

[0068] By comparing the test data of Examples 1-25, it can be seen that using acidic water with a pH of 1.5-3.0, activated carbon with a particle size of 20-40μm, diatomaceous earth with a particle size of 5-15μm, and porous starch can further improve the stability of the adsorption efficiency of ceramic-based composite activated carbon filter cartridges under long-term liquid flow impact.

[0069] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A ceramic-based composite activated carbon filter element, characterized in that, The raw materials include the following parts by weight: 40-60 parts of coated modified activated carbon, 1-3 parts of carbon nanofibers, 5-15 parts of kaolin, 12-15 parts of silica sol, 8-10 parts of alumina sol, and 2-3 parts of pore-forming agent; the coated modified activated carbon is a core-shell material with diatomaceous earth-supported nano-titanium oxide composite material as the shell and activated carbon as the core; based on the total weight of the coated modified activated carbon, the raw materials include the following parts by weight: 100 parts of activated carbon, 10-30 parts of diatomaceous earth, and 15-45 parts of tetrabutyl titanate; the coated modified activated carbon is prepared according to the following steps: Diatomaceous earth was dispersed in ethanol to obtain a diatomaceous earth dispersion with a mass concentration of 8-10%. Tetrabutyl titanate was added to ethanol and mixed evenly to obtain a tetrabutyl titanate solution with a mass concentration of 8-10%. The diatomaceous earth dispersion was added to the tetrabutyl titanate solution and stirred until homogeneous. Deionized water was added, and the mixture was stirred at 50-60℃ for 2-3 hours. After filtration and drying, diatomaceous earth / Ti(OH)4 powder was obtained. The molar ratio of tetrabutyl titanate to deionized water was 1:(3.9-4.2). Diatomaceous earth / Ti(OH)4 powder was calcined at 280-320℃ for 1-2 hours and then naturally cooled to obtain diatomaceous earth-supported nano-titanium oxide composite material. The diatomaceous earth-supported nano-titanium oxide composite material was dispersed in acidic water and stirred evenly to obtain a sol. Activated carbon is added to the sol and stirred for 3-5 hours under water bath heating at 60-70℃. After filtration and drying, coated modified activated carbon is obtained. The ceramic-based composite activated carbon filter element is prepared according to the following steps: According to the formula, after uniformly mixing the coated modified activated carbon, kaolin, carbon nanofibers and pore-forming agent, silica sol and alumina sol are added, deionized water is added, and the mixture is stirred evenly to obtain a paste-like slurry with a solid content between 55% and 65%. Three layers of paste-like slurry are extruded simultaneously and coaxially using a three-layer co-extrusion die to form a green filter element with a gradient structure. After standing at room temperature with a humidity of 90-95% for 12-24 hours and drying, the filter element is heat-treated at 340-360℃ for 2-2.5 hours and then naturally cooled to room temperature to obtain a ceramic-based composite activated carbon filter element.

2. The ceramic-based composite activated carbon filter element according to claim 1, characterized in that, The pH of the acidic water is 1.5-3.

0.

3. The ceramic-based composite activated carbon filter element according to claim 1, characterized in that, The activated carbon has a particle size of 20-40 μm.

4. The ceramic-based composite activated carbon filter element according to claim 1, characterized in that, The particle size of the diatomaceous earth is 5-15 μm.

5. The ceramic-based composite activated carbon filter element according to claim 1, characterized in that, The pore-forming agent is porous starch.

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