Composite oxidized particle filter material and preparation method thereof

Abstract

The invention discloses a composite oxidized particle filter material and a preparation method thereof, and particularly relates to the technical field of oxidized particle filter materials, the filter material takes a ternary composite oxide of cerium dioxide-cobaltosic oxide-nickel oxide as a core material, has a hierarchical pore structure, and is coated with a pH responsive coating on the surface; the preparation method comprises the following steps: S1, biological template pretreatment; S2, sol-gel synthesis; S3, graded pore channel construction; and S4, surface modification. According to the invention, the cerium dioxide-cobaltosic oxide-nickel oxide ternary composite oxide is taken as a core, pollutants are efficiently degraded under visible light and infrared light by virtue of graded pore channels, surface copper nanoparticles and internal up-conversion nanoparticles, and the quaternary ammonium salt compound grafted on the surface has good antibacterial property, can inhibit microorganism breeding and prolong the service life of the filter material; the whole preparation process is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of oxidized particle filter materials, and more specifically, to a composite oxidized particle filter material and a preparation method thereof. Background Art

[0002] In the field of environmental pollution control, water purification and air purification have always been key problems that need to be solved urgently. Traditional filter materials have exposed many limitations when dealing with increasingly complex pollution conditions. Common single-component filter materials, due to their single function, are difficult to meet the needs of efficient removal of multiple pollutants at the same time. For example, although activated carbon filter materials have certain adsorption capacity, they are not effective in treating certain organic pollutants and microorganisms.

[0003] As environmental pollution becomes increasingly serious, higher requirements are placed on filter media performance. On the one hand, there are often a variety of pollutants in water, such as heavy metal ions, organic compounds, and pathogenic microorganisms, and filter media must be able to effectively adsorb and degrade these pollutants at the same time. On the other hand, harmful gases and particulate matter in the air also urgently need a multifunctional filter media to achieve purification.

[0004] The structure and composition design of existing filter materials cannot fully utilize advanced technologies such as photocatalysis to improve purification efficiency. At the same time, during long-term use of the filter material, microorganisms are likely to grow on its surface, causing filter material blockage, reduced purification performance, and even secondary pollution.

[0005] In view of the above situation, the present invention provides a composite oxidized particle filter material and a preparation method thereof. Summary of the invention

[0006] In order to overcome the above-mentioned defects of the prior art, the present invention provides a composite oxidized particle filter material and a preparation method thereof to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solution: a composite oxidized particle filter material, wherein the filter material particles are regular spherical, and the particle size distribution is between 0.5-2 mm, the filter material is made of a ternary composite oxide of cerium dioxide-cobalt tetraoxide-nickel oxide as a core material, has a hierarchical pore structure, and is coated with a pH responsive coating on the surface;

[0008] The molar ratio of cerium dioxide, cobalt oxide and nickel oxide in the ternary composite oxide is 5:3:2;

[0009] The graded pore structure includes macropores, mesopores and micropores, wherein the pore size of macropores is 50-500nm, the pore size of mesopores is 2-50nm, the pore size of micropores is less than 2nm, and the specific surface area of ​​the filter material is ≥200m² / g;

[0010] The pH-responsive coating is composited with polymethacrylic acid and graphene oxide.

[0011] Preferably, the surface of the filter material is loaded with copper nanoparticles, the particle size of the copper nanoparticles is 5-10 nm, and the loading amount is 5 wt %.

[0012] Preferably, the pH responsive coating has a thickness of 50-100 nm.

[0013] Preferably, carbon nanotubes are evenly dispersed inside the filter material, and the mass of the carbon nanotubes accounts for 1%-3% of the total mass of the filter material, which is used to enhance the mechanical strength and electronic conductivity of the filter material and improve the efficiency of the catalytic reaction.

[0014] Preferably, the filter material is doped with up-conversion nanoparticles to convert infrared light into visible light, thereby improving the filter material's ability to degrade pollutants under visible and infrared light, and the doping amount is 0.5wt%-2wt%.

[0015] Preferably, the filter material surface is grafted with a quaternary ammonium salt compound having antibacterial properties, with a grafting rate of 0.2mmol / g-0.5mmol / g, so that the filter material has antibacterial function while purifying pollutants and inhibiting the growth of microorganisms on the filter material surface.

[0016] The present invention also provides a preparation method for preparing the composite oxidized particle filter material, which specifically comprises the following preparation steps:

[0017] S1. Biological template pretreatment,

[0018] S1.1, immersing bacterial cellulose in a mixed solution of cerium nitrate, cobalt nitrate and nickel nitrate with a concentration of 0.1-0.5 mol / L, stirring for 24 hours, so that the metal ions are loaded into the pores of the template;

[0019] S1.2. Before the pretreatment of the bio-template, the bacterial cellulose is subjected to surface hydrophilization treatment by soaking it in a 3%-5% by mass silane coupling agent aqueous solution for 3-5 hours, then rinsed with deionized water and dried;

[0020] S2, sol-gel synthesis,

[0021] S2.1, adding citric acid and ethylene glycol in a molar ratio of 1:1-1:3 to the solution in step S1.1, adjusting the pH to 6-7, and forming a sol;

[0022] S2.2, at the same time, adding the carbon nanotube suspension treated with ultrasonic dispersion to the sol, the amount of carbon nanotubes added is controlled to account for 1%-3% of the total mass of the filter material, the ultrasonic dispersion frequency of the carbon nanotube suspension is 30-50kHz, and the time is 20-40min;

[0023] S2.3, then microwave heating at a power of 500 W for 10 min to promote gelation and form a precursor;

[0024] S2.4, after the sol-gel synthesis is completed, the formed precursor is spray dried, the air inlet temperature is controlled at 180-220°C, and the air outlet temperature is controlled at 80-100°C, so that the precursor forms spherical particles with uniform particle size, and the particles with a particle size in the range of 0.3-0.8 mm are screened out by a vibrating screen;

[0025] S3, hierarchical channel construction,

[0026] S3.1, freeze-drying the precursor in step S2.3, and calcining at 600°C for 4 h in a nitrogen atmosphere to remove the biological template and form a hierarchical porous structure;

[0027] S3.2, then, immersing the hierarchical porous structure in a solution containing upconversion nanoparticles, wherein the concentration of the solution is adjusted according to the final doping amount of the upconversion nanoparticles of 0.5wt%-2wt%, and the immersion temperature is maintained at 40-60°C for 8-12h, so that the upconversion nanoparticles are uniformly doped into the filter material, giving the filter material a photothermal conversion function;

[0028] S3.3, after the hierarchical pores are constructed, the hierarchical porous structure is subjected to pulse electric field treatment, with an electric field strength of 1-3 kV / cm, a pulse frequency of 10-20 Hz, and a treatment time of 5-10 min;

[0029] S3.4, vacuum annealing treatment is performed on the hierarchical porous structure, and the vacuum degree is 10 -3 -10 -2 Pa, annealing temperature is 400-500℃, time is 2-3h;

[0030] S4. Surface modification,

[0031] S4.1, using a chemical reduction method to load copper nanoparticles on the particle surface, the reducing agent is sodium borohydride, wherein the molar ratio of sodium borohydride to copper ions is 2:1-4:1;

[0032] S4.2, then a layer-by-layer self-assembly treatment is performed, before coating the composite coating of polymethacrylic acid and graphene oxide, firstly, a positively charged polyelectrolyte and a negatively charged functional nanoparticle are alternately adsorbed on the surface of the filter material, and the adsorption time of each layer is 10-20 minutes, so as to form a multi-layer composite structure;

[0033] S4.3, after completing the layer-by-layer self-assembly, immerse the filter material in a grafting solution containing a quaternary ammonium salt compound, the concentration of the grafting solution is 0.5-1.5 mol / L, the reaction temperature is 50-70°C, the reaction time is 3-5h, so that the grafting rate on the filter material surface reaches 0.2mmol / g-0.5mmol / g, giving the filter material antibacterial properties;

[0034] S4.4. Finally, the polymethacrylic acid and graphene oxide composite coating is coated by electrospinning technology to form a pH responsive coating. The spinning voltage is 10-20 kV, the spinning distance is 10-15 cm, and the flow rate of the spinning solution is 0.5-1.5 mL / h. In the process of electrospinning to coat the polymethacrylic acid and graphene oxide composite coating, 0.5%-2% of nano-titanium dioxide is added to the spinning solution. After the electrospinning is completed, the filter material coated with the pH responsive coating is subjected to ultraviolet curing treatment. The ultraviolet wavelength is 254 nm and the irradiation time is 15-30 min.

[0035] Preferably, after adding the carbon nanotube suspension in step S2.2, the sol is subjected to high-speed centrifugation, the centrifugal speed is 8000-12000 rpm, and the centrifugal time is 5-10 min.

[0036] Preferably, when soaking the upconversion nanoparticle solution in step S3.2, ultrasound-assisted soaking is adopted, the ultrasound frequency is 40-60kHz, and the ultrasound power is 100-200W.

[0037] Preferably, in the layer-by-layer self-assembly process of step S4.2, electric field-assisted adsorption is introduced, and a DC electric field with an intensity of 0.5-1.5 kV / cm is applied to the surface of the filter material to promote faster and more uniform adsorption of polyelectrolytes and functional nanoparticles on the surface of the filter material, shortening the adsorption time of each layer by 3-5 minutes and improving the stability of the multilayer composite structure by 40%-50%.

[0038] Technical effects and advantages of the present invention:

[0039] 1. The filter material of the present invention is based on the ternary composite oxide of cerium dioxide-cobalt oxide-nickel oxide. The unique hierarchical pore structure provides a huge specific surface area. The macropores are conducive to the rapid entry of pollutants, and the mesopores and micropores increase the adsorption sites. At the same time, the copper nanoparticles loaded on the surface can catalyze the decomposition of pollutants, and the internally doped upconversion nanoparticles can convert infrared light into visible light, which broadens the spectral range of photocatalysis and greatly improves the ability of the filter material to degrade pollutants under visible light and infrared light;

[0040] 2. The filter material surface of the present invention is grafted with a quaternary ammonium salt compound with antibacterial properties. In the process of purifying pollutants, the quaternary ammonium salt compound can effectively inhibit the growth of microorganisms on the filter material surface, thereby ensuring the hygienic safety of the filter material during use, preventing secondary pollution, extending the service life of the filter material, and maintaining its stable purification effect;

[0041] 3. In the preparation process of the present invention, bacterial cellulose is used as a biological template, and the metal ions are accurately loaded in the pores of the template by soaking in a mixed solution of cerium nitrate, cobalt nitrate and nickel nitrate. In the sol-gel synthesis stage, the molar ratio of citric acid to ethylene glycol and the pH value are reasonably controlled, and ultrasonically dispersed carbon nanotubes are added to enhance the mechanical strength and electronic conductivity of the filter material. When constructing the graded pores, freeze drying, high-temperature calcination, pulse electric field and vacuum annealing are used to accurately control the pore structure. In the surface modification step, chemical reduction method is used to load copper nanoparticles, layer-by-layer self-assembly is combined with electric field-assisted adsorption, and electrospinning is used to coat pH-responsive coatings. The synergistic effect gives the filter material a variety of excellent properties. The entire preparation process is mature and highly operable, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0043] Embodiment 1,

[0044] The present embodiment provides a composite oxidized particle filter material, whose filter material particles are regular spherical and have a particle size distribution between 0.5-2 mm. The filter material uses a ternary composite oxide of cerium dioxide-cobalt oxide-nickel oxide as a core material, has a graded pore structure, and is coated with a pH responsive coating on the surface; wherein the molar ratio of cerium dioxide, cobalt oxide and nickel oxide in the ternary composite oxide is 5:3:2; the graded pore structure includes macropores, mesopores and micropores, wherein the macropore diameter is 50-500 nm, the mesopore diameter is 2-50 nm, the micropore diameter is less than 2 nm, and the specific surface area of ​​the filter material is ≥200 m² / g; the pH responsive coating is composited by polymethacrylic acid and graphene oxide.

[0045] This embodiment also provides a preparation method for preparing the composite oxidized particle filter material of this embodiment, which specifically includes the following steps:

[0046] S1. Biological template pretreatment

[0047] S1.1. Weigh an appropriate amount of bacterial cellulose and completely immerse it in a mixed solution of cerium nitrate, cobalt nitrate and nickel nitrate with a concentration of 0.1 mol / L. Place it on a magnetic stirrer and stir it at a speed of 150 rpm for 24 h to enable the metal ions to be fully loaded into the pores of the template.

[0048] S1.2. Before proceeding to S1.1, BC was immersed in a 3% aqueous solution of silane coupling agent for 3 h, then rinsed with deionized water for 3 times, each time for 3 min, and then dried in an oven at 60 °C for 2 h.

[0049] S2. Sol-gel synthesis

[0050] S2.1, transferring the mixed solution soaked with bacterial cellulose in S1.1 to a three-necked flask, slowly adding citric acid and ethylene glycol mixed in a 1:1 molar ratio under stirring, and adjusting the pH to 6 with 0.1 mol / L sodium hydroxide solution and 0.1 mol / L hydrochloric acid solution to form a sol;

[0051] S2.2, weighing carbon nanotubes accounting for 1% of the total mass of the final filter material, adding them to 150 mL of anhydrous ethanol, and performing ultrasonic dispersion treatment at an ultrasonic frequency of 30 kHz for 20 min to prepare a uniform carbon nanotube suspension, and slowly dripping the suspension into the above sol. After the dripping is completed, the sol is subjected to high-speed centrifugation at a centrifugal speed of 8000 rpm and a centrifugal time of 5 min;

[0052] S2.3, put the three-necked flask into a microwave oven and heat it at a power of 500 W for 10 min to promote gelation and obtain a precursor;

[0053] S2.4, transfer the precursor to a spray dryer, set the inlet air temperature to 180°C and the outlet air temperature to 80°C for spray drying to obtain spherical particles with uniform particle size, and use a vibrating screen to screen out particles with a particle size in the range of 0.3-0.8 mm and collect them;

[0054] S3. Hierarchical channel construction

[0055] S3.1, put the screened spherical particles into a freeze dryer, freeze-dry them at -50 °C for 10 h, then transfer them to a tube furnace, and calcine them at 600 °C for 4 h in a nitrogen atmosphere to remove the biological template and form a hierarchical porous structure;

[0056] S3.2, weigh an appropriate amount of upconversion nanoparticles, add them to 80mL of deionized water to prepare a solution, the concentration of the solution is adjusted according to the final doping amount of the upconversion nanoparticles of 0.5wt%, soak the hierarchical porous structure in this solution, soak it in a constant temperature water bath at 40°C for 8h, and use ultrasound-assisted soaking at a frequency of 40kHz and a power of 100W to uniformly dope the upconversion nanoparticles into the filter material;

[0057] S3.3, placing the doped hierarchical porous structure in a pulsed electric field device, applying a pulsed electric field with an electric field strength of 1 kV / cm and a pulse frequency of 10 Hz for 5 minutes;

[0058] S3.4, transfer the hierarchical porous structure after pulse electric field treatment to a vacuum annealing furnace and heat it at a vacuum degree of 10 -3 Pa, annealing temperature is 400℃ for 2h;

[0059] S4. Surface modification

[0060] S4.1, prepare 80mL of 0.1mol / L copper sulfate solution, take 40mL and add it to the above-mentioned hierarchical porous structure, slowly add 20mL of 0.2mol / L sodium borohydride aqueous solution (the molar ratio of sodium borohydride to copper ions is 2:1) under stirring, and react for 25min to load copper nanoparticles onto the particle surface;

[0061] S4.2, soak the filter material loaded with copper nanoparticles in a 0.05 mol / L positively charged polyelectrolyte solution, apply a DC electric field with a strength of 0.5 kV / cm on the surface of the filter material, take it out after adsorption for 7 minutes, rinse it with deionized water 3 times, 2 minutes each time, then soak it in a 0.05 mol / L negatively charged functional nanoparticle dispersion, apply an electric field in the same way, take it out after adsorption for 7 minutes, and rinse it with deionized water 3 times, and alternately adsorb it 4 times to form a multilayer composite structure. The stability of this structure is 40% higher than that without electric field assistance;

[0062] S4.3, soak the filter material after layer-by-layer self-assembly in a 0.5 mol / L quaternary ammonium salt compound grafting solution, and react in a 50°C water bath for 3 hours to make the grafting rate on the filter material surface reach 0.2 mmol / g;

[0063] S4.4. Dissolve polymethacrylic acid and graphene oxide in dimethylformamide at a mass ratio of 2:1 to prepare a spinning solution with a concentration of 0.08 g / mL, add 0.5% mass fraction of nano-titanium dioxide, and ultrasonically disperse for 20 minutes. Use an electrospinning device to coat a polymethacrylic acid and graphene oxide composite coating under the conditions of a spinning voltage of 10 kV, a spinning distance of 10 cm, and a spinning solution flow rate of 0.5 mL / h to form a pH-responsive coating. After the electrospinning is completed, place the filter material under an ultraviolet lamp with a wavelength of 254 nm for 15 minutes for curing.

[0064] Performance Test:

[0065] 1. Structure and morphology: Using a scanning electron microscope to observe the surface morphology and pore structure of the filter material, it was found that the filter material particles were regular spherical, with a particle size distribution between 0.5 and 2 mm, a distinct hierarchical pore structure, and the distribution of macropores, mesopores and micropores met the requirements;

[0066] 2. Component analysis: The crystal structure of the filter material was analyzed by X-ray diffractometer to determine the presence of cerium dioxide-cobalt oxide-nickel oxide ternary composite oxide, and the molar ratio of cerium dioxide, cobalt oxide and nickel oxide was 5:3:2. The elemental composition and chemical state of the filter material surface were analyzed by X-ray photoelectron spectrometer to verify the loading of copper nanoparticles and the grafting of quaternary ammonium salt compounds.

[0067] 3. Specific surface area and pore size distribution: Through nitrogen adsorption-desorption test, the specific surface area of ​​the filter material is 205m² / g, the macropore size is between 50-500nm, the mesopore size is between 2-50nm, and the micropore size is less than 2nm;

[0068] 4. Photothermal conversion performance: Use an infrared thermal imager to monitor the temperature change of the filter material under simulated sunlight (including infrared light) to verify its photothermal conversion function. By degrading organic pollutants such as methyl orange, the filter material's ability to degrade pollutants under visible and infrared light was tested, and the degradation rate reached 82%;

[0069] 5. Antibacterial performance: Escherichia coli and Staphylococcus aureus were used for antibacterial tests. The filter material was mixed with the bacterial solution and the inhibition rate was calculated by the plate count method. The results showed that the inhibition rate was 86%, indicating that the filter material has good antibacterial properties.

[0070] Embodiment 2,

[0071] The present embodiment provides a composite oxidized particle filter material, whose filter material particles are regular spherical and have a particle size distribution between 0.5-2 mm. The filter material uses a ternary composite oxide of cerium dioxide-cobalt oxide-nickel oxide as a core material, has a graded pore structure, and is coated with a pH responsive coating on the surface; wherein the molar ratio of cerium dioxide, cobalt oxide and nickel oxide in the ternary composite oxide is 5:3:2; the graded pore structure includes macropores, mesopores and micropores, wherein the macropore diameter is 50-500 nm, the mesopore diameter is 2-50 nm, the micropore diameter is less than 2 nm, and the specific surface area of ​​the filter material is ≥200 m² / g; the pH responsive coating is composited by polymethacrylic acid and graphene oxide.

[0072] This embodiment also provides a preparation method for preparing the composite oxidized particle filter material of this embodiment, which specifically includes the following steps:

[0073] S1. Biological template pretreatment

[0074] S1.1. Weigh an appropriate amount of bacterial cellulose and completely immerse it in a mixed solution of cerium nitrate, cobalt nitrate and nickel nitrate with a concentration of 0.5 mol / L. Place it on a magnetic stirrer and stir it at 250 rpm for 24 h to allow the metal ions to be fully loaded into the pores of the template.

[0075] S1.2. Before proceeding to S1.1, BC was immersed in a 5% by mass silane coupling agent aqueous solution for 5 h, then rinsed with deionized water for 4 times, 5 min each time, and then dried in an oven at 70 °C for 3 h.

[0076] S2. Sol-gel synthesis

[0077] S2.1, transfer the mixed solution soaked with bacterial cellulose in S1.1 to a three-necked flask, slowly add citric acid and ethylene glycol mixed in a molar ratio of 1:3 under stirring, and adjust the pH to 7 with 0.1 mol / L sodium hydroxide solution and 0.1 mol / L hydrochloric acid solution to form a sol;

[0078] S2.2, weigh carbon nanotubes accounting for 3% of the total mass of the final filter material, add them to 250 mL of anhydrous ethanol, perform ultrasonic dispersion treatment at an ultrasonic frequency of 50 kHz for 40 minutes to prepare a uniform carbon nanotube suspension, slowly drop the suspension into the above sol, and after the dropwise addition is completed, perform high-speed centrifugation on the sol at a centrifugal speed of 12,000 rpm for 10 minutes;

[0079] S2.3, put the three-necked flask into a microwave oven and heat it at a power of 500 W for 10 min to promote gelation and obtain a precursor;

[0080] S2.4, transfer the precursor to a spray dryer, set the air inlet temperature to 220°C and the air outlet temperature to 100°C for spray drying, obtain spherical particles with uniform particle size, and use a vibrating screen to screen out particles with a particle size in the range of 0.3-0.8 mm and collect them;

[0081] S3. Hierarchical channel construction

[0082] S3.1, put the screened spherical particles into a freeze dryer, freeze-dry them at -50 °C for 14 h, then transfer them to a tube furnace, and calcine them at 600 °C for 4 h in a nitrogen atmosphere to remove the biological template and form a hierarchical porous structure;

[0083] S3.2, weigh an appropriate amount of upconversion nanoparticles, add them to 120mL of deionized water, prepare a solution, the concentration of the solution is adjusted according to the final doping amount of the upconversion nanoparticles is 2wt%, soak the hierarchical porous structure in this solution, soak it in a constant temperature water bath at 60°C for 12h, and use ultrasound to assist soaking, the ultrasound frequency is 60kHz, and the ultrasound power is 200W, so that the upconversion nanoparticles are evenly doped into the filter material;

[0084] S3.3, placing the doped hierarchical porous structure in a pulsed electric field device, applying a pulsed electric field with an electric field strength of 3 kV / cm and a pulse frequency of 20 Hz for 10 min;

[0085] S3.4, transfer the hierarchical porous structure after pulse electric field treatment to a vacuum annealing furnace and heat it at a vacuum degree of 10 -2 Pa, annealing temperature is 500℃ for 3h;

[0086] S4. Surface modification

[0087] S4.1. Prepare 120 mL of 0.1 mol / L copper sulfate solution, take 60 mL and add it to the above-mentioned hierarchical porous structure. Under stirring, slowly add 30 mL of an aqueous solution containing 0.2 mol / L sodium borohydride (the molar ratio of sodium borohydride to copper ions is 4:1), and react for 35 minutes to load copper nanoparticles onto the particle surface.

[0088] S4.2, soak the filter material loaded with copper nanoparticles in a 0.08 mol / L positively charged polyelectrolyte solution, apply a DC electric field with a strength of 1.5 kV / cm on the surface of the filter material, take it out after adsorption for 15 minutes, and rinse it with deionized water 4 times, 4 minutes each time; then soak it in a 0.08 mol / L negatively charged functional nanoparticle dispersion, apply an electric field in the same way, take it out after adsorption for 15 minutes, and rinse it with deionized water 4 times, and alternately adsorb it 6 times to form a multilayer composite structure, the stability of which is 50% higher than that without electric field assistance;

[0089] S4.3, soak the filter material after layer-by-layer self-assembly in a 1.5 mol / L quaternary ammonium salt compound grafting solution, and react in a 70°C water bath for 5 hours to make the grafting rate on the filter material surface reach 0.5 mmol / g;

[0090] S4.4. Dissolve polymethacrylic acid and graphene oxide in dimethylformamide at a mass ratio of 4:1 to prepare a spinning solution with a concentration of 0.12 g / mL, add 2% nano-titanium dioxide by mass, and ultrasonically disperse for 40 minutes; use an electrospinning device to apply a polymethacrylic acid and graphene oxide composite coating under the conditions of a spinning voltage of 20 kV, a spinning distance of 15 cm, and a spinning solution flow rate of 1.5 mL / h to form a pH-responsive coating. After the electrospinning is completed, place the filter material under an ultraviolet lamp with a wavelength of 254 nm for 30 minutes for curing.

[0091] Performance Test:

[0092] 1. Structure and morphology: The surface morphology and pore structure of the filter material were observed by scanning electron microscope. It can be seen that the filter material particles are regular spherical, with a particle size distribution between 0.5-2mm, a clear graded pore structure, and the distribution of macropores, mesopores and micropores meets the requirements;

[0093] 2. Component analysis: The crystal structure of the filter material was analyzed by X-ray diffractometer to determine the presence of cerium dioxide-cobalt oxide-nickel oxide ternary composite oxide, and the molar ratio of cerium dioxide, cobalt oxide and nickel oxide was 5:3:2. The elemental composition and chemical state of the filter material surface were analyzed by X-ray photoelectron spectrometer to verify the loading of copper nanoparticles and the grafting of quaternary ammonium salt compounds.

[0094] 3. Specific surface area and pore size distribution: Through nitrogen adsorption-desorption test, the specific surface area of ​​the filter material is 230m² / g, the macropore size is between 50-500nm, the mesopore size is between 2-50nm, and the micropore size is less than 2nm;

[0095] 4. Photothermal conversion performance: Use an infrared thermal imager to monitor the temperature change of the filter material under simulated sunlight (including infrared light) to verify its photothermal conversion function. By degrading organic pollutants such as methyl orange, the filter material's ability to degrade pollutants under visible and infrared light was tested, and the degradation rate reached 91%;

[0096] 5. Antibacterial performance: Escherichia coli and Staphylococcus aureus were used for antibacterial tests. The filter material was mixed with the bacterial solution and the inhibition rate was calculated by the plate count method. The results showed that the inhibition rate was 96%, indicating that the filter material has good antibacterial properties.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite oxidized particle filter material, wherein the filter material particles are regular spherical, and the particle size distribution is between 0.5-2mm, characterized in that: The filter material has a ternary composite oxide of cerium dioxide-cobalt oxide-nickel oxide as a core material, has a hierarchical pore structure, and is coated with a pH responsive coating on the surface; The molar ratio of cerium dioxide, cobalt oxide and nickel oxide in the ternary composite oxide is 5:3:2; The graded pore structure includes macropores, mesopores and micropores, wherein the pore size of macropores is 50-500nm, the pore size of mesopores is 2-50nm, the pore size of micropores is less than 2nm, and the specific surface area of ​​the filter material is ≥200m² / g; The pH-responsive coating is composited with polymethacrylic acid and graphene oxide.

2. The composite oxidized particle filter material according to claim 1, characterized in that: The surface of the filter material is loaded with copper nanoparticles, the particle size of the copper nanoparticles is 5-10nm, and the loading amount is 5wt%.

3. The composite oxidized particle filter material according to claim 2, characterized in that: The thickness of the pH responsive coating was 50-100 nm.

4. The composite oxidized particle filter material according to claim 3, characterized in that: Carbon nanotubes are evenly dispersed inside the filter material. The mass of the carbon nanotubes accounts for 1%-3% of the total mass of the filter material. They are used to enhance the mechanical strength and electronic conductivity of the filter material and improve the efficiency of the catalytic reaction.

5. The composite oxidized particle filter material according to claim 4, characterized in that: The filter material is doped with upconversion nanoparticles to convert infrared light into visible light, thereby improving the filter material's ability to degrade pollutants under visible and infrared light. The doping amount is 0.5wt%-2wt%.

6. The composite oxidized particle filter material according to claim 5, characterized in that: The surface of the filter material is grafted with quaternary ammonium salt compounds with antibacterial properties, with a grafting rate of 0.2mmol / g-0.5mmol / g. The filter material has antibacterial function while purifying pollutants, and inhibits the growth of microorganisms on the surface of the filter material.

7. A preparation method for preparing the composite oxidized particle filter material according to claim 6, characterized in that: Specifically include the following preparation steps: S1. Biological template pretreatment, S1.1, immersing bacterial cellulose in a mixed solution of cerium nitrate, cobalt nitrate and nickel nitrate with a concentration of 0.1-0.5 mol / L, stirring for 24 hours, so that the metal ions are loaded into the pores of the template; S1.

2. Before the pretreatment of the bio-template, the bacterial cellulose is subjected to surface hydrophilization treatment by soaking it in a 3%-5% by mass silane coupling agent aqueous solution for 3-5 hours, then rinsed with deionized water and dried; S2, sol-gel synthesis, S2.1, adding citric acid and ethylene glycol in a molar ratio of 1:1-1:3 to the solution in step S1.1, adjusting the pH to 6-7, and forming a sol; S2.2, at the same time, adding the carbon nanotube suspension treated with ultrasonic dispersion to the sol, the amount of carbon nanotubes added is controlled to account for 1%-3% of the total mass of the filter material, the ultrasonic dispersion frequency of the carbon nanotube suspension is 30-50kHz, and the time is 20-40min; S2.3, then microwave heating at a power of 500 W for 10 min to promote gelation and form a precursor; S2.4, after the sol-gel synthesis is completed, the formed precursor is spray dried, the air inlet temperature is controlled at 180-220°C, and the air outlet temperature is controlled at 80-100°C, so that the precursor forms spherical particles with uniform particle size, and the particles with a particle size in the range of 0.3-0.8 mm are screened out by a vibrating screen; S3, hierarchical channel construction, S3.1, freeze-drying the precursor in step S2.3, and calcining at 600°C for 4 h in a nitrogen atmosphere to remove the biological template and form a hierarchical porous structure; S3.2, then, immersing the hierarchical porous structure in a solution containing upconversion nanoparticles, wherein the concentration of the solution is adjusted according to the final doping amount of the upconversion nanoparticles of 0.5wt%-2wt%, and the immersion temperature is maintained at 40-60°C for 8-12h, so that the upconversion nanoparticles are uniformly doped into the filter material, giving the filter material a photothermal conversion function; S3.3, after the hierarchical pores are constructed, the hierarchical porous structure is subjected to pulse electric field treatment, with an electric field strength of 1-3 kV / cm, a pulse frequency of 10-20 Hz, and a treatment time of 5-10 min; S3.4, vacuum annealing treatment is performed on the hierarchical porous structure, and the vacuum degree is 10 -3 -10 -2 Pa, annealing temperature is 400-500℃, time is 2-3h; S4. Surface modification, S4.1, using chemical reduction method to load copper nanoparticles on the particle surface, the reducing agent is sodium borohydride, wherein the molar ratio of sodium borohydride to copper ions is 2:1-4:1; S4.2, then a layer-by-layer self-assembly treatment is performed, before coating the composite coating of polymethacrylic acid and graphene oxide, firstly, a positively charged polyelectrolyte and a negatively charged functional nanoparticle are alternately adsorbed on the surface of the filter material, and the adsorption time of each layer is 10-20 minutes, so as to form a multi-layer composite structure; S4.3, after completing the layer-by-layer self-assembly, immerse the filter material in a grafting solution containing a quaternary ammonium salt compound, the concentration of the grafting solution is 0.5-1.5 mol / L, the reaction temperature is 50-70°C, the reaction time is 3-5h, so that the grafting rate on the filter material surface reaches 0.2mmol / g-0.5mmol / g, giving the filter material antibacterial properties; S4.

4. Finally, the polymethacrylic acid and graphene oxide composite coating is coated by electrospinning technology to form a pH responsive coating. The spinning voltage is 10-20 kV, the spinning distance is 10-15 cm, and the flow rate of the spinning solution is 0.5-1.5 mL / h. In the process of electrospinning to coat the polymethacrylic acid and graphene oxide composite coating, 0.5%-2% of nano-titanium dioxide is added to the spinning solution. After the electrospinning is completed, the filter material coated with the pH responsive coating is subjected to ultraviolet curing treatment. The ultraviolet wavelength is 254 nm and the irradiation time is 15-30 min.

8. The preparation method according to claim 7, characterized in that: After the carbon nanotube suspension is added in step S2.2, the sol is subjected to high-speed centrifugation at a speed of 8000-12000 rpm for 5-10 min.

9. The preparation method according to claim 8, characterized in that: When soaking the upconversion nanoparticle solution in step S3.2, ultrasound-assisted soaking is used, with an ultrasound frequency of 40-60kHz and an ultrasound power of 100-200W.

10. The preparation method according to claim 9, characterized in that: During the layer-by-layer self-assembly process in step S4.2, electric field-assisted adsorption is introduced, and a DC electric field with an intensity of 0.5-1.5 kV / cm is applied to the filter material surface to promote faster and more uniform adsorption of polyelectrolytes and functional nanoparticles on the filter material surface, shortening the adsorption time of each layer by 3-5 minutes and improving the stability of the multilayer composite structure by 40%-50%.

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