Graded porous nano ceramsite filtering catalytic material for new pollutants as well as preparation method and application of graded porous nano ceramsite filtering catalytic material

Abstract

The invention discloses a new pollutant-oriented graded porous nano ceramsite filtering catalytic material and a preparation method and application thereof.According to the filtering catalytic material, ferroferric oxide serves as an inner core, titanium dioxide serves as a coating layer, cerium dioxide serves as a catalytic outer layer, and the inner core, the coating layer and the catalytic outer layer form graded porous nano ceramic particles of a sandwich structure; the catalyst is prepared by a combined method of microemulsion confined synthesis, magnetic field assisted molding, sonochemical cavitation reaming and dipping roasting. The filtering catalytic material is environment-friendly, not only can efficiently filter micro-plastic particles in water, but also can catalytically degrade organic matters in wastewater under the condition of ultraviolet light, and has relatively high economic value and scientific significance.

Description

Technical Field

[0001] The invention relates to a hierarchical porous nano-ceramic particle filtering catalytic material for new pollutants, a preparation method and application thereof, and belongs to the field of water treatment. Background Art

[0002] Water pollution has become a global environmental challenge, with the combined effects of microplastics and dyes being particularly prominent. According to the United Nations Environment Programme, approximately 8 million tons of plastic waste enters the oceans annually, 94% of which persists in the form of microplastics. These microplastics not only pose a direct threat to aquatic life but also act as "toxic vectors" by absorbing heavy metals and organic pollutants. For example, DDT concentrations adsorbed on the surfaces of microplastics in the North Atlantic Gyre can reach 1,000 times the background value in seawater. More seriously, microplastics have entered the human food chain, being detected in bottled water, table salt, and even placental tissue. The chronic inflammatory responses and endocrine disruption they trigger have been listed as potential health risks by the World Health Organization. Meanwhile, methyl orange, a typical azo dye, is consumed annually worldwide in excess of 200,000 tons, 10%-15% of which enters water bodies with printing and dyeing wastewater. The azo bond (-N=N-) and aromatic ring in its molecular structure impart exceptional chemical stability, resulting in a natural degradation cycle of up to 200 days. Studies have shown that even 10 mg / L of methyl orange can inhibit algal photosynthesis, leading to a decrease in dissolved oxygen in water. Its degradation intermediate, aniline derivatives, are classified as Class 2B carcinogens by the International Agency for Research on Cancer. Furthermore, the interaction between microplastics and methyl orange significantly exacerbates the pollution effect. The hydrophobic surface of microplastics causes them to adsorb methyl orange, forming a persistent source of pollution. Therefore, the development of an efficient, sustainable, and multifunctional material that can achieve synergistic management of microplastics with the catalytic degradation of methyl orange is an urgent need in the field of environmental materials. Summary of the Invention

[0003] The purpose of the present invention is to address the current situation and existing problems in the field of water pollution treatment and to propose a hierarchical porous nano-ceramic particle filtration catalytic material for new pollutants and its preparation method and application.

[0004] The present invention can be realized by the following technical scheme: the filtering catalytic material uses ferroferric oxide as the core, and the ferroferric oxide is prepared by co-precipitation of ferric salt and ferrous salt. At the same time, in order to avoid the agglomeration of ferroferric oxide nanoparticles, the Fe 3+ and Fe 2+Ions co-precipitate in the water core of the microemulsion, which can limit the excessive growth of ferroferric oxide nanoparticles; surfactants can also be adsorbed on the surface of ferroferric oxide nanoparticles to form a stably dispersed colloid, which is convenient for the coating and deposition of titanium dioxide; in addition, in order to construct a macroporous channel for filtering catalytic materials and reduce fluid resistance, the present invention uses a magnetic field to induce Fe3O4@TiO2 to form a directional pore structure. At the same time, in order to avoid excessive agglomeration of Fe3O4@TiO2 under the magnetic field, a self-made intermittent magnetic field is used to induce the growth of nanoparticles; in order to expand the pores of Fe3O4@TiO2 and open up the internal closed pores to form a three-dimensional The present invention has a connected network structure and adopts sonochemical cavitation pore expansion technology. Ultrasonic waves are used to generate cavitation bubbles in the liquid. The bubbles release energy instantly when they collapse and act on the pores of the material, thereby increasing the porosity of the material. The cavitation microjets can also form nano-scale concave-convex structures on the pore walls, increasing sites for the subsequent impregnation and loading of cerium dioxide. Finally, the present invention uses an impregnation and roasting method to load cerium dioxide inside the material pores to form sandwich-structured hierarchical porous nano-ceramic particles, which enable the sandwich-structured hierarchical porous nano-ceramic particles to not only have the function of filtering microplastics, but also be able to catalytically degrade organic pollutants such as methyl orange under ultraviolet light.

[0005] The present invention can be achieved through the following technical solutions:

[0006] A hierarchical porous nano-ceramic filtration catalytic material for new pollutants. This filtration catalytic material has a core of ferroferric oxide, a coating of titanium dioxide, and a catalytic outer layer of ceria. The core-coating-catalytic outer layer forms a sandwich structure of hierarchical porous nano-ceramic particles. It is prepared by a combined process of microemulsion confined synthesis, magnetic field-assisted molding, sonochemical cavitation pore expansion, and impregnation and calcination.

[0007] The parts by weight of each component are as follows:

[0008] 20 to 40 kernels

[0009] 50-75 parts of coating layer

[0010] 5 to 10 parts of the catalytic outer layer.

[0011] A method for preparing the above-mentioned filtering catalytic material is as follows:

[0012] (1) Microemulsion confined synthesis of Fe3O4@TiO2 core-shell structure

[0013] Iron salt, ferrous salt and deionized water are uniformly mixed to obtain a mixed solution A, and nitrogen is continuously introduced. Microemulsion surfactant A is added to the mixed solution A and stirred continuously. After the microemulsion surfactant A is completely dissolved and the mixed solution A becomes transparent, the solution is placed in a water bath stirrer, and ammonia water is slowly added thereto at a temperature of 70 to 90° C. while stirring and introducing nitrogen, and the mixture is reacted for 4 to 8 hours. After the reaction is completed, filtration is performed to obtain ferroferric oxide colloid.

[0014] The microemulsion oil phase and the microemulsion surfactant B are uniformly mixed to obtain a mixed solution B, and ferroferric oxide colloid is added to the mixed solution B for ultrasonic dispersion to obtain a mixed solution D. Titanium salt, anhydrous ethanol, and acetic acid are uniformly mixed to obtain a mixed solution C. The mixed solution C is then slowly added to the mixed solution D at a temperature of 40 to 60° C. to react for 2 to 4 hours. After the reaction is completed, the mixture is centrifuged, filtered, washed, and finally dried to obtain Fe3O4@TiO2 powder.

[0015] (2) Preparation of porous ceramic skeletons by magnetic field-assisted molding and sonochemical cavitation expansion

[0016] The binder, the Fe3O4@TiO2 powder obtained in step (1), and deionized water are uniformly mixed and ultrasonically dispersed to obtain a slurry, the slurry is injected into a container and then placed next to a relay-coupled electromagnet, the relay is used to control the electromagnet to form an intermittent magnetic field to assist in forming, and after the auxiliary forming, the slurry is placed in a muffle furnace and low-temperature roasted to obtain a pre-sintered green body; the pre-sintered green body is placed in a container and deionized water is added, and then placed in an ultrasonic cleaner to utilize ultrasonic cavitation to pre-sinter the green body, and finally placed in an atmosphere furnace, and nitrogen is introduced and roasted to obtain a porous ceramic skeleton;

[0017] (3) Preparation of catalytic materials by impregnation and calcination

[0018] The cerium salt and deionized water are mixed evenly to prepare a precursor solution, and then the porous ceramic skeleton prepared in step (2) is placed in the precursor solution, immersed and then dried, and finally placed in a muffle furnace for calcination to obtain a filtering catalytic material.

[0019] In the above preparation method: the iron salt described in step (1) is ferric nitrate nonahydrate or ferric chloride hexahydrate, the ferrous salt is ferrous nitrate or ferrous chloride, the microemulsion surfactant A is hexadecyltrimethylammonium bromide, the mass ratio of the iron salt to the microemulsion surfactant A is 5-15:(1-10), and the molar ratio of the iron salt to the ferrous salt is 1:1.

[0020] The mass fraction of ammonia water is 15-20%. The addition of ammonia water is to adjust the pH of the reaction system to 9-10.

[0021] In the above preparation method: the microemulsion oil phase described in step (1) is cyclohexane, and the microemulsion surfactant B is n-hexanol; the mass ratio of ferrosoferric oxide colloid, microemulsion oil phase, and microemulsion surfactant B is 1:(10-20):(3-5), the ultrasonic dispersion power is 200-300W, and the ultrasonic dispersion time is 10-30min.

[0022] In the above preparation method: the titanium salt described in step (1) is tetrabutyl titanate or tetraethyl titanate, the mass ratio of titanium salt, anhydrous ethanol and acetic acid is 1: (30-50): (3-5); the drying temperature is 80-100° C., and the drying time is 4-8 hours.

[0023] In the above preparation method: the binder described in step (2) is polyvinyl alcohol with a molecular weight of 80,000 to 100,000, the mass ratio of Fe3O4@TiO2 powder to binder is 5 to 15: (0.1 to 1), the power of ultrasonic dispersion is 200 to 300 W, and the ultrasonic dispersion time is 10 to 30 minutes; the relay is a solid-state relay, which realizes a cycle instruction of powering the electromagnet for 0.1 to 0.5 seconds and then powering off for 5 to 10 seconds, the electromagnet is an iron wire with a diameter of 2 to 3 mm wound around a metal rod with a diameter of 10 to 20 cm, and the auxiliary molding time is 20 to 30 minutes;

[0024] The temperature of low-temperature roasting is 350-400° C., and the time of low-temperature roasting is 3-5 hours.

[0025] In the above preparation method: the power of ultrasonic cavitation in step (2) is 300-500W, and the ultrasonic cavitation time is 1-2h; the rate of nitrogen introduction is 30-50mL / min, the calcination temperature is 800-900°C, and the calcination time is 3-6h.

[0026] In the above preparation method: the cerium salt described in step (3) is cerium nitrate hexahydrate or cerium chloride, the mass ratio of the cerium salt to deionized water is 1:(10-20), the impregnation time is 30-60 minutes; the drying temperature is 80-100°C, and the drying time is 4-8 hours; the roasting temperature is 500-700°C, and the roasting time is 3-6 hours.

[0027] In the technical solution of the present invention, the application of the filtration catalytic material in filtering microplastics in water and catalytically degrading organic matter is further characterized in that the organic pollutant is methyl orange.

[0028] Beneficial effects:

[0029] The filtering catalytic material is prepared by combining microemulsion confined synthesis, magnetic field-assisted molding and sonochemical cavitation expansion to obtain a Fe3O4@TiO2 porous ceramic skeleton. At the same time, cerium dioxide is loaded by impregnation and calcination, so that a material with a stable pore structure and a uniform distribution of active components can be obtained. The magnetic properties of ferroferric oxide enable the filtering catalytic material to be easily recycled after catalytically reducing methyl orange and filtering microplastics in water. The synergistic catalytic effect of ferroferric oxide and titanium dioxide can also be utilized to enhance the catalytic degradation effect of cerium dioxide and titanium dioxide. The components of the filtering catalytic material are environmentally friendly, can efficiently catalytically reduce p-nitrophenol in wastewater, and have strong application and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Example 1 Schematic diagram of the principle of magnetic field assisted molding equipment for preparing catalyst;

[0031] Figure 2 FE-SEM image of the catalyst prepared in Example 1;

[0032] Figure 3 This is the BET full-pore pore size distribution diagram of the catalyst prepared in Example 1. DETAILED DESCRIPTION

[0033] The following examples further illustrate the preparation method of the hierarchical porous nano-ceramic filtration catalytic material for new pollutants described in the present invention.

[0034] Example 1

[0035] (1) Microemulsion confined synthesis of Fe3O4@TiO2 core-shell structure

[0036] Weigh 8.080g of ferric nitrate nonahydrate, 1.799g of ferrous nitrate, and 80.800g of deionized water, mix them uniformly to obtain a mixed solution A, and continuously introduce nitrogen into the mixed solution A (the rate of introducing nitrogen is 20mL / min). Weigh 3.232g of hexadecyltrimethylammonium bromide and add it to the mixed solution A and continue stirring at a rate of 100r / min for 2h. After the hexadecyltrimethylammonium bromide is completely dissolved and the mixed solution A is transparent, the mixed solution A is placed in a water bath stirrer, and 15% ammonia water is slowly added dropwise under continuous constant temperature stirring and nitrogen flow (70°C, stirring rate of 100r / min, nitrogen flow rate of 20mL / min) until the pH of the mixed solution A reaches 10. After reacting in a water bath for 4h, filter to obtain ferroferric oxide colloid;

[0037] 23.150 g of cyclohexane and 6.945 g of n-hexanol were weighed and mixed to obtain a mixed solution B. 2.315 g of ferroferric oxide colloid was added to the mixed solution B and ultrasonically dispersed at a power of 200 W for 30 min to obtain a mixed solution D.

[0038] 36.992 g of tetrabutyl titanate, 1109.760 g of anhydrous ethanol and 110.976 g of acetic acid were weighed and mixed to obtain a mixed solution C. The mixed solution C was then added dropwise to the mixed solution D during constant temperature stirring (the constant temperature stirring temperature was 40°C and the constant temperature stirring rate was 100 r / min). After constant temperature stirring for 4 h, the reaction was completed by centrifugation at 7000 rpm for 10 min, filtered, washed three times with anhydrous ethanol and deionized water, respectively, and finally dried at 80°C for 8 h to obtain Fe3O4@TiO2 powder.

[0039] (2) Preparation of porous ceramic skeletons by magnetic field-assisted molding and sonochemical cavitation expansion

[0040] Weigh 0.475 g of polyvinyl alcohol with a molecular weight of 80,000, 9.500 g of Fe3O4@TiO2 powder obtained in step (1), and 95.000 g of deionized water, mix them evenly, and ultrasonically disperse them at a power of 200 W for 30 minutes to obtain a slurry. Pour the slurry into a beaker and place it next to a solid-state relay coupled electromagnet. Use the solid-state relay to control the electromagnet to form an intermittent magnetic field to assist molding for 30 minutes (a cycle instruction of powering the electromagnet for 0.1 seconds and then powering off for 5 seconds, the electromagnet is A 2 mm diameter iron wire was wrapped around a 10 cm diameter metal rod), and after auxiliary forming, the slurry was placed in a muffle furnace and calcined at 350°C for 5 h to obtain a pre-sintered green body; 9.500 g of the pre-sintered green body was placed in a beaker and 190 g of deionized water was added, and then the beaker was placed in an ultrasonic cleaner and ultrasonically cavitated at a power of 300 W for 2 h. Finally, the pre-sintered green body was placed in an atmosphere furnace and nitrogen was introduced at a rate of 30 mL / min and calcined at 800°C for 6 h to obtain a porous ceramic skeleton;

[0041] (3) Preparation of filtration catalytic materials by impregnation and calcination

[0042] 0.631 g of cerium nitrate hexahydrate and 6.310 g of deionized water were weighed and mixed uniformly to prepare a precursor solution, and then 4.750 g of the porous ceramic skeleton prepared in step (2) was weighed and placed in the precursor solution. After immersion for 30 minutes, the porous ceramic skeleton was dried at 80° C. for 8 hours, and finally placed in a muffle furnace and calcined at 500° C. for 6 hours to obtain a filtering catalytic material (based on the catalytic material, the mass percentage of the core is 20%, the mass percentage of the coating layer is 75%, and the mass percentage of the catalytic outer layer is 5%).

[0043] (4) Evaluation of microplastic filtration performance

[0044] Weigh 5.000g of high-density polyethylene particles and place them in 50mL of liquid nitrogen for freezing for 10min. Then place them in a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300rpm for 3h. Then use 220-mesh and 300-mesh metal sieves to sieve the milled particles. Take 0.200g of high-density polyethylene powder with a particle size of 50-65μm and 200g of deionized water in a 250mL beaker (beaker mass 102.088g) and mix them evenly. Then, heat at 300W. The microplastic simulation liquid was obtained by ultrasonic dispersion at a power of 100 for 30 minutes. 1 g of the filtration catalytic material was taken and loaded into a vertical quartz tube with an inner diameter of 6 mm. The tail end of the quartz tube was wrapped with a 100-mesh metal sieve. The microplastic simulation liquid was then slowly poured into the quartz tube and filtered through the catalytic material to collect the filtered tail liquid. The filtered tail liquid was placed in an oven at 60°C and dried until all deionized water was evaporated. The total mass of the polyethylene powder in the beaker and the tail liquid (102.101 g) was weighed, and the filtration efficiency of the filtration catalytic material was calculated to be 93.5%;

[0045] (5) Evaluation of methyl orange catalytic performance

[0046] Weigh 0.200g of methyl orange powder and dissolve it in 1000mL of deionized water to prepare a 200mg / L methyl orange mother solution. Then weigh 50mL of the mother solution and dilute it to 500mL to obtain a 20mg / L methyl orange solution and measure the absorbance (1.61). Weigh 1g of the filtered catalytic material and add it to 500mL of the 20mg / L methyl orange solution. After standing in the dark for 1h, the mixed solution is placed under a UV lamp with an irradiation intensity calibrated to 10mW / cm 2 After 20 minutes, 5 mL of the mixed solution was taken and placed in an ultraviolet spectrophotometer to measure the absorbance (0.03). The efficiency of the catalytic degradation of methyl orange by the filter catalytic material was calculated to be 95.7%.

[0047] Example 2

[0048] (1) Microemulsion confined synthesis of Fe3O4@TiO2 core-shell structure

[0049] Weigh 5.406g of ferric chloride hexahydrate, 1.268g of ferrous chloride, and 108.120g of deionized water, mix them uniformly to obtain a mixed solution A, and continuously introduce nitrogen into the mixed solution A (the rate of introducing nitrogen is 50mL / min). Weigh 4.325g of hexadecyltrimethylammonium bromide and add it to the mixed solution A. Stir continuously at a rate of 200r / min for 1h. After the hexadecyltrimethylammonium bromide is completely dissolved and the mixed solution A becomes transparent, place the mixed solution A in a water bath stirrer, and slowly add 20% ammonia water by mass dropwise under conditions of continuous constant temperature stirring and nitrogen introduction (90°C, stirring rate of 200r / min, nitrogen introduction rate of 50mL / min) until the pH of the mixed solution A reaches 10. After reacting in a water bath for 8h, filter to obtain ferroferric oxide colloid;

[0050] 46.300 g of cyclohexane and 11.575 g of n-hexanol were weighed and mixed to obtain a mixed solution B. 2.315 g of ferroferric oxide colloid was added to the mixed solution B and ultrasonically dispersed at a power of 300 W for 10 min to obtain a mixed solution D.

[0051] 8.265 g of tetraethyl titanate, 413.250 g of anhydrous ethanol and 41.325 g of acetic acid were weighed and mixed to obtain a mixed solution C. The mixed solution C was then added dropwise to the mixed solution D during constant temperature stirring (the constant temperature stirring temperature was 60°C and the constant temperature stirring rate was 200 r / min). The mixture was stirred at constant temperature for 2 h. After the reaction was completed, the mixture was centrifuged at 9000 rpm for 5 min, filtered, washed three times with anhydrous ethanol and deionized water, respectively, and finally dried at 100°C for 4 h to obtain Fe3O4@TiO2 powder.

[0052] (2) Preparation of porous ceramic skeletons by magnetic field-assisted molding and sonochemical cavitation expansion

[0053] Weigh 0.500 g of polyvinyl alcohol with a molecular weight of 100,000, 5.000 g of Fe3O4@TiO2 powder obtained in step (1), and 100.000 g of deionized water, mix them evenly, and ultrasonically disperse them at a power of 300 W for 10 min to obtain a slurry. Pour the slurry into a beaker and place it next to a solid-state relay coupled electromagnet. Use the solid-state relay to control the electromagnet to form an intermittent magnetic field to assist molding for 20 min (a cycle instruction of powering the electromagnet for 0.5 s and then powering off for 10 s, the electromagnet (a 3 mm diameter iron wire is wound around a 20 cm diameter metal rod), and after auxiliary forming, the slurry is placed in a muffle furnace and calcined at 400°C for 3 h to obtain a pre-sintered green body; 5.000 g of the pre-sintered green body is placed in a beaker and 150 g of deionized water is added, and then the beaker is placed in an ultrasonic cleaner and ultrasonically cavitated at a power of 500 W for 1 h. Finally, the pre-sintered green body is placed in an atmosphere furnace and nitrogen is introduced at a rate of 50 mL / min and calcined at 900°C for 3 h to obtain a porous ceramic skeleton;

[0054] (3) Preparation of filtration catalytic materials by impregnation and calcination

[0055] 0.716 g of cerium chloride and 14.320 g of deionized water were weighed and mixed uniformly to prepare a precursor solution, and then 4.500 g of the porous ceramic skeleton prepared in step (2) was weighed and placed in the precursor solution. After immersion for 60 min, the porous ceramic skeleton was dried at 100° C. for 4 h, and finally placed in a muffle furnace and calcined at 700° C. for 3 h to obtain a filtering catalytic material (based on the catalytic material, the mass percentage of the core is 40%, the mass percentage of the coating layer is 50%, and the mass percentage of the catalytic outer layer is 10%).

[0056] (4) Evaluation of microplastic filtration performance

[0057] Weigh 5.000g of high-density polyethylene particles and place them in 50mL of liquid nitrogen for freezing for 10min. Then place them in a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300rpm for 3h. Then use 220-mesh and 300-mesh metal sieves to sieve the milled particles. Take 0.200g of high-density polyethylene powder with a particle size of 50-65μm and 200g of deionized water in a 250mL beaker (beaker mass 102.088g) and mix them evenly. Then, heat at 300W. The microplastic simulation liquid was obtained by ultrasonic dispersion at a power of 100 for 30 minutes. 1 g of the filtration catalytic material was loaded into a vertical quartz tube with an inner diameter of 6 mm. The tail end of the quartz tube was wrapped with a 100-mesh metal sieve. The microplastic simulation liquid was then slowly poured into the quartz tube and filtered through the catalytic material to collect the filtered tail liquid. The filtered tail liquid was placed in an oven at 60°C and dried until all deionized water was evaporated. The total mass of the polyethylene powder in the beaker and the tail liquid was weighed (102.097 g). The filtration efficiency of the filtration catalytic material was calculated to be 95.5%;

[0058] (5) Evaluation of methyl orange catalytic performance

[0059] Weigh 0.200g of methyl orange powder and dissolve it in 1000mL of deionized water to prepare a 200mg / L methyl orange mother solution. Then weigh 50mL of the mother solution and dilute it to 500mL to obtain a 20mg / L methyl orange solution and measure the absorbance (1.61). Weigh 1g of the filtered catalytic material and add it to 500mL of the 20mg / L methyl orange solution. After standing in the dark for 1h, the mixed solution is placed under a UV lamp with an irradiation intensity calibrated to 10mW / cm 2 After 20 minutes, 5 mL of the mixed solution was taken and placed in an ultraviolet spectrophotometer to measure the absorbance (0.02). The efficiency of the catalytic degradation of methyl orange by the filter catalytic material was calculated to be 98.8%.

[0060] Comparative Example 1

[0061] (1) Preparation of filtration catalytic materials

[0062] Except that cyclohexane was not used in the catalyst preparation, other conditions were the same as those in Example 1;

[0063] (2) Evaluation of microplastic filtration performance

[0064] Weigh 5.000g of high-density polyethylene particles and place them in 50mL of liquid nitrogen for freezing for 10min. Then place them in a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300rpm for 3h. Then use 220-mesh and 300-mesh metal sieves to sieve the milled particles. Take 0.200g of high-density polyethylene powder with a particle size of 50-65μm and 200g of deionized water in a 250mL beaker (beaker mass 102.088g) and mix them evenly. Then, heat at 300W. The microplastic simulation liquid was obtained by ultrasonic dispersion at a power of 100 for 30 minutes. 1 g of the filtration catalytic material was loaded into a vertical quartz tube with an inner diameter of 6 mm. The tail end of the quartz tube was wrapped with a 100-mesh metal sieve. The microplastic simulation liquid was then slowly poured into the quartz tube and filtered through the catalytic material to collect the filtered tail liquid. The filtered tail liquid was placed in an oven at 60°C and dried until all deionized water was evaporated. The total mass of the polyethylene powder in the beaker and the tail liquid was weighed (102.110 g). The filtration efficiency of the filtration catalytic material was calculated to be 89.0%;

[0065] (3) Evaluation of methyl orange catalytic performance

[0066] Weigh 0.200g of methyl orange powder and dissolve it in 1000mL of deionized water to prepare a 200mg / L methyl orange mother solution. Then weigh 50mL of the mother solution and dilute it to 500mL to obtain a 20mg / L methyl orange solution and measure the absorbance (1.61). Weigh 1g of the filtered catalytic material and add it to 500mL of the 20mg / L methyl orange solution. After standing in the dark for 1h, the mixed solution is placed under a UV lamp with an irradiation intensity calibrated to 10mW / cm 2 After 20 minutes, 5 mL of the mixed solution was taken and placed in a UV spectrophotometer to measure the absorbance (0.59). The efficiency of the catalytic degradation of methyl orange by the filter catalytic material was calculated to be 63.4%.

[0067] (3) Contrast effect

[0068] Compared with Example 1, cyclohexane is not used in the catalyst preparation step (1), and microemulsion confined synthesis cannot be performed during the preparation process. Therefore, ferrosoferric oxide and titanium dioxide will agglomerate. Although the effect on the microplastic filtration effect is small, the agglomeration causes a reduction in the active sites of cerium dioxide and a decrease in the specific surface area of ​​the filtration catalytic material. Therefore, the catalytic performance of methyl orange is significantly reduced.

[0069] Comparative Example 2

[0070] (1) Preparation of filtration catalytic materials

[0071] Except that the relay-coupled electromagnet was not used in the catalyst preparation, other conditions were the same as those in Example 2;

[0072] (2) Evaluation of microplastic filtration performance

[0073] Weigh 5.000g of high-density polyethylene particles and place them in 50mL of liquid nitrogen for freezing for 10min. Then place them in a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300rpm for 3h. Then use 220-mesh and 300-mesh metal sieves to sieve the milled particles. Take 0.200g of high-density polyethylene powder with a particle size of 50-65μm and 200g of deionized water in a 250mL beaker (beaker mass 102.088g) and mix them evenly. Then, heat at 300W. The microplastic simulation liquid was obtained by ultrasonic dispersion at a power of 100 for 30 minutes. 1 g of the filtration catalytic material was taken and loaded into a vertical quartz tube with an inner diameter of 6 mm. The tail end of the quartz tube was wrapped with a 100-mesh metal sieve. The microplastic simulation liquid was then slowly poured into the quartz tube and filtered through the catalytic material to collect the filtered tail liquid. The filtered tail liquid was placed in an oven at 60°C and dried until all deionized water was evaporated. The total mass of the polyethylene powder in the beaker and the tail liquid was weighed (102.215 g). The filtration efficiency of the filtration catalytic material was calculated to be 36.5%;

[0074] (3) Evaluation of methyl orange catalytic performance

[0075] Weigh 0.200g of methyl orange powder and dissolve it in 1000mL of deionized water to prepare a 200mg / L methyl orange mother solution. Then weigh 50mL of the mother solution and dilute it to 500mL to obtain a 20mg / L methyl orange solution and measure the absorbance (1.61). Weigh 1g of the filtered catalytic material and add it to 500mL of the 20mg / L methyl orange solution. After standing in the dark for 1h, the mixed solution is placed under a UV lamp with an irradiation intensity calibrated to 10mW / cm 2 After 20 minutes, 5 mL of the mixed solution was taken and placed in a UV spectrophotometer to measure the absorbance (0.37). The efficiency of the catalytic degradation of methyl orange by the filter catalytic material was calculated to be 77.0%.

[0076] (3) Contrast effect

[0077] Compared with Example 2, the catalyst preparation step (1) does not use a relay-coupled electromagnet, and the magnetic field-assisted molding cannot be formed during the preparation process. Fe3O4@TiO2 cannot form a directional pore structure, which will also lead to a significant decrease in specific surface area. Therefore, the filtration effect and catalytic degradation efficiency are significantly reduced.

Claims

1. A hierarchical porous nano-ceramic filtration catalytic material for new pollutants, characterized by: The filtering catalytic material has ferroferric oxide as the core, titanium dioxide as the coating layer, and ceria as the catalytic outer layer. The core-coating layer-catalytic outer layer form a sandwich structure of hierarchical porous nano-ceramic particles, which are prepared by a combined method of microemulsion confined synthesis-magnetic field assisted molding-sonic chemical cavitation pore expansion-impregnation and calcination. The parts by weight of each component are as follows: 20 to 40 kernels 50-75 parts of coating layer 5 to 10 parts of the catalytic outer layer.

2. A method for preparing the filtering catalytic material according to claim 1, characterized in that: The preparation method of the filtering catalytic material is as follows: (1) Microemulsion confined synthesis of Fe3O4@TiO2 core-shell structure Iron salt, ferrous salt and deionized water are uniformly mixed to obtain a mixed solution A, and nitrogen is continuously introduced. Microemulsion surfactant A is added to the mixed solution A and stirred continuously. After the microemulsion surfactant A is completely dissolved and the mixed solution A becomes transparent, the solution is placed in a water bath stirrer, and ammonia water is slowly added thereto at a temperature of 70 to 90° C. while stirring and introducing nitrogen, and the mixture is reacted for 4 to 8 hours. After the reaction is completed, filtration is performed to obtain ferroferric oxide colloid. The microemulsion oil phase and the microemulsion surfactant B are uniformly mixed to obtain a mixed solution B, and ferrosoferric oxide colloid is added to the mixed solution B for ultrasonic dispersion to obtain a mixed solution D; Titanium salt, anhydrous ethanol and acetic acid are uniformly mixed to obtain a mixed solution C, which is then slowly added to a mixed solution D at a temperature of 40 to 60°C for a reaction of 2 to 4 hours. After the reaction, the mixture is centrifuged, filtered and washed, and finally dried to obtain Fe3O4@TiO2 powder. (2) Preparation of porous ceramic skeletons by magnetic field-assisted molding and sonochemical cavitation expansion The binder, the Fe3O4@TiO2 powder obtained in step (1), and deionized water are uniformly mixed and ultrasonically dispersed to obtain a slurry, the slurry is injected into a container and then placed next to a relay-coupled electromagnet, the relay is used to control the electromagnet to form an intermittent magnetic field to assist in forming, and after the auxiliary forming, the slurry is placed in a muffle furnace and low-temperature roasted to obtain a pre-sintered green body; the pre-sintered green body is placed in a container and deionized water is added, and then placed in an ultrasonic cleaner to utilize ultrasonic cavitation to pre-sinter the green body, and finally placed in an atmosphere furnace, and nitrogen is introduced and roasted to obtain a porous ceramic skeleton; (3) Preparation of catalytic materials by impregnation and calcination The cerium salt and deionized water are mixed evenly to prepare a precursor solution, and then the porous ceramic skeleton prepared in step (2) is placed in the precursor solution, immersed and then dried, and finally placed in a muffle furnace for calcination to obtain a filtering catalytic material.

3. The preparation method according to claim 2, wherein: The iron salt described in step (1) is ferric nitrate nonahydrate or ferric chloride hexahydrate, the ferrous salt is ferrous nitrate or ferrous chloride, the microemulsion surfactant A is hexadecyltrimethylammonium bromide, the mass ratio of the iron salt to the microemulsion surfactant A is 5-15:(1-10), and the molar ratio of the iron salt to the ferrous salt is 1:

1. The mass fraction of ammonia water is 15-20%. The addition of ammonia water is to adjust the pH of the reaction system to 9-10.

4. The preparation method according to claim 2, wherein: The microemulsion oil phase described in step (1) is cyclohexane, and the microemulsion surfactant B is n-hexanol; the mass ratio of ferroferric oxide colloid, microemulsion oil phase, and microemulsion surfactant B is 1:(10-20):(3-5), the ultrasonic dispersion power is 200-300W, and the ultrasonic dispersion time is 10-30min.

5. The preparation method according to claim 2, wherein: The titanium salt described in step (1) is tetrabutyl titanate or tetraethyl titanate, and the mass ratio of the titanium salt, anhydrous ethanol and acetic acid is 1: (30-50): (3-5); the drying temperature is 80-100° C., and the drying time is 4-8 hours.

6. The preparation method according to claim 2, wherein: The binder described in step (2) is polyvinyl alcohol with a molecular weight of 80,000 to 100,000, the mass ratio of Fe3O4@TiO2 powder to binder is 5 to 15: (0.1 to 1), the power of ultrasonic dispersion is 200 to 300 W, and the ultrasonic dispersion time is 10 to 30 minutes; the relay is a solid-state relay, which realizes a cycle instruction of powering the electromagnet for 0.1 to 0.5 seconds and then powering off for 5 to 10 seconds, the electromagnet is an iron wire with a diameter of 2 to 3 mm wound around a metal rod with a diameter of 10 to 20 cm, and the auxiliary molding time is 20 to 30 minutes; The temperature of low-temperature roasting is 350-400° C., and the time of low-temperature roasting is 3-5 hours.

7. The preparation method according to claim 2, characterized in that: In step (2), the power of ultrasonic cavitation is 300-500W, and the time of ultrasonic cavitation is 1-2h; the rate of nitrogen introduction is 30-50mL / min, the calcination temperature is 800-900°C, and the calcination time is 3-6h.

8. The preparation method according to claim 2, wherein: The cerium salt described in step (3) is cerium nitrate hexahydrate or cerium chloride, the mass ratio of the cerium salt to deionized water is 1:(10-20), the impregnation time is 30-60 minutes; the drying temperature is 80-100°C, and the drying time is 4-8 hours; the roasting temperature is 500-700°C, and the roasting time is 3-6 hours.

9. Use of the filtering catalytic material according to claim 1 in filtering microplastics in water and catalytically degrading organic matter.

10. The use according to claim 10, characterized in that The organic pollutant is methyl orange.

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