A silicon carbide microreactor for ozone catalysis and a preparation method and application thereof

Abstract

The application relates to the technical field of water treatment, in particular to a silicon carbide micro-reactor for ozone catalysis and a preparation method and application thereof. The silicon carbide micro-reactor comprises the following steps: S1, mixing silicon carbide powder, metal oxide, a binder and a dispersing agent in a solvent, ball-milling the mixture to obtain slurry liquid, and drying the slurry liquid to form a mud; S2, molding the mud in a mold to obtain a blank; and S3, sintering the blank in an inert gas atmosphere, and cooling the blank to obtain the silicon carbide micro-reactor. Compared with the prior art, the metal oxide is connected between silicon carbide particles in the form of a sintering neck in the application, the formed sintering neck has ozone catalysis function, a large number of three-dimensional network through micro-reactors are formed, and efficient degradation of dye wastewater is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a silicon carbide micro-reactor for ozone catalysis and a preparation method and application thereof. BACKGROUND

[0002] China is a big country in textile production and use, and the annual use of dyes accounts for more than 83% of the global total. The dyeing and printing industry produces a large amount of dye wastewater in the production process, which accounts for about 11% of the total industrial wastewater in China. According to statistics, the annual output of textiles in China can reach 800 million tons, and 100 billion tons of dye wastewater need to be discharged. Dye wastewater has the characteristics of complex composition, high colority, high chemical oxygen demand, difficult degradation, high toxicity, and difficult treatment. Untreated dye wastewater will pollute the nearby water body and soil, causing serious harm to the ecological environment. Therefore, the development of efficient, economical and green dye wastewater treatment technology is an important measure for current sustainable development.

[0003] Ozone is a kind of advanced oxidation technology, which uses the strong oxidizing property (oxidation-reduction potential 2.07V) of ozone to oxidize and degrade organic pollutants in wastewater. It has the advantages of simple operation and low running cost, and is widely used in industrial wastewater treatment. However, direct ozone oxidation has low catalytic efficiency and cannot deeply mineralize organic matter. Therefore, some metal oxides are used to catalyze ozonation. Metal oxides can provide a large number of active sites to accelerate the decomposition of ozone to generate active oxygen species, and improve the degradation efficiency of organic matter. However, in the gas-liquid-solid three-phase ozone catalytic oxidation process, ozone is difficult to dissolve in water, and the mass transfer resistance of gas bubbles is large, making it difficult to reach the inside of the catalyst and interact with the active sites, resulting in limited reaction kinetics and low ozone utilization rate. Patent (CN104803512A) prepares a layer of titanium-manganese or titanium-cerium catalytic layer on the surface of the ceramic membrane by dip coating method, which catalyzes the dissolved ozone in water and realizes the self-cleaning effect of the membrane. However, the catalytic layer has the risk of blocking the membrane pores, and the catalytic layer is easy to fall off during backwashing, resulting in poor stability. SUMMARY

[0004] The present application relates to the technical field of water treatment, in particular to a silicon carbide micro-reactor for ozone catalysis and a preparation method and application thereof.

[0005] The purpose of the present application can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present application is to provide a preparation method of a silicon carbide micro-reactor for ozone catalysis, comprising the following steps:

[0007] S1, put silicon carbide powder, metal oxide, binder and dispersant into solvent, mix and ball mill to obtain slurry, dry to form a paste;

[0008] S2, the obtained paste is molded in a mold to obtain a green body;

[0009] S3, the obtained green body is sintered in an inert gas atmosphere, and a silicon carbide micro-reactor is obtained after cooling.

[0010] Further, in step S1, the metal oxide includes one or more of zinc oxide, cobalt oxide, iron oxide, manganese oxide, nickel oxide, and cerium oxide, which is different from the commonly used oxides such as aluminum oxide, magnesium oxide, zirconium oxide, and silicon dioxide in the prior art. The metal oxide can form a sintered neck with a catalytic ozone function.

[0011] The binder includes one or more of polyethylene glycol, polyvinyl alcohol, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose, and polyacrylic acid;

[0012] The dispersant includes one or more of tetramethylammonium hydroxide, sodium polyacrylate, ammonium polyacrylate, polycarbonate, polyethyleneimine, sodium alginate, and ammonium polymethacrylate;

[0013] The solvent includes ethanol or water.

[0014] Further, in step S1, the mass-volume ratio of the silicon carbide powder, metal oxide, binder, dispersant, and solvent is (10-15):(2-10):(1-5):(0.8-2):(20-30).

[0015] Further, in step S1, the average particle size of the silicon carbide powder is 10-20 μm;

[0016] The average particle size of the metal oxide is 0.1-2 μm.

[0017] Further, in step S2, the specific process of molding is: the obtained paste is dry-pressed under a pressure of 20-40 MPa, dried at room temperature for 6-24 h, and then secondarily dry-pressed under a pressure of 40-70 MPa to obtain a green body.

[0018] Further, in step S3, the specific process of sintering is: the temperature is raised to 800-900℃ at a rate of 2-5℃ / min, and then held for 1-3 h, and then raised to 1200-1500℃ at a rate of 2-5℃ / min, and then held for 1-3 h.

[0019] The second technical solution of the present application provides a silicon carbide micro-reactor for ozone catalysis, which is prepared by the preparation method, and has a three-dimensional network through structure formed by the sintering necks of the metal oxide catalysts.

[0020] Further, the most probable pore size of the silicon carbide micro-reactor is 1-5 μm, and the porosity is 60%-80%.

[0021] The third technical solution of the present application provides an application of the silicon carbide micro-reactor for ozone catalysis in the field of water treatment, and the wastewater treated by the silicon carbide micro-reactor for ozone catalysis includes Congo red, chrome black T, active red 195, active bright blue Kn-R, indigo, acid blue, or acid orange 52II.

[0022] The fourth technical solution of the present application provides a water treatment system for ozone catalysis, and the silicon carbide micro-reactor is filled in the up-flow reaction tower.

[0023] Further, the water treatment system further includes:

[0024] a wastewater storage tank connected with the up-flow reaction tower and used for storing the wastewater to be treated;

[0025] and an ozone generator connected with the up-flow reaction tower and used for feeding the generated ozone into the up-flow reaction tower for catalysis, wherein the ozone generator is connected with the bottom of the up-flow reaction tower.

[0026] Further, the pipeline connecting the ozone generator with the up-flow reaction tower is further connected with a ball valve, a flow meter, and an ozone detector.

[0027] Further, the water treatment system further includes a vacuum pump for recycling the treated effluent into the wastewater storage tank, wherein the vacuum pump is connected with the top of the up-flow reaction tower.

[0028] The catalyst in the micro-reactor can increase the transmission rate and contact time of ozone in the water body, so that the ozone is decomposed to generate active oxygen species (such as hydroxyl radical ·OH, superoxide radical O2 ·- ), which can react with organic pollutants to degrade them. Compared with direct ozonation, the micro-reactor has advantages in improving the treatment efficiency and reducing secondary pollution. Among them, the selection of the catalyst and the sintering procedure control in step S3 have a significant influence on the formation of the sintering necks.

[0029] Compared with the prior art, the present application has the following advantages:

[0030] (1) The catalyst of the traditional supported catalytic ceramic membrane is distributed on the membrane surface, which is easy to flow out and cause secondary pollution in the reaction. The catalyst of the present application is distributed between the silicon carbide particles in the form of sintering neck, which greatly relieves the problem of catalyst loss.

[0031] (2) When the wastewater dissolved with ozone passes through the silicon carbide support, the sintering neck structure formed by the metal oxide can effectively catalyze the formation of hydroxyl radicals in the confined space, thereby improving the performance of ozone catalytic degradation of organic matter.

[0032] (3) The metal oxide and the silicon carbide powder are interpenetrated, which effectively inhibits the agglomeration of silicon carbide. The metal oxide is used as a sintering aid, which can form a low-viscosity liquid phase, promote atomic transfer at low temperature, and form a sintering neck between the silicon carbide particles, thereby effectively reducing the sintering temperature of silicon carbide.

[0033] (4) The traditional supported catalytic ceramic membrane is coated or filtered with catalyst on the surface of the silicon carbide membrane, which will block part of the membrane holes and is not conducive to the transmission of ozone. At the same time, the binding force between the catalyst and the silicon carbide is weak, and the catalyst is easy to fall off. The present application sintering silicon carbide and catalyst together to form a pore structure in the gap between the particles, which does not have the problem of membrane hole blockage. In addition, the contact and combination of the catalyst and the silicon carbide reduce the surface energy, and the strong binding force between the particles avoids the catalyst from falling off. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The metal oxide sintering neck structure of the silicon carbide microreactor in Example 1, A) SEM picture, B) structure schematic diagram;

[0035] Figure 2 SEM pictures of the silicon carbide microreactor shown in each example, A) Example 1, B) Example 2, C) Example 3;

[0036] Figure 3 The contact angle of the silicon carbide microreactor shown in each example, A) Example 1, B) Example 2, C) Example 3;

[0037] Figure 4 The device schematic diagram of the water treatment system;

[0038] Figure 5 The degradation effect of the silicon carbide microreactor shown in each example on dyes, A) Example 1, B) Example 2, C) Example 3, D) Example 6, E) Example 7, F) Example 8, G) Example 9, H) Example 10;

[0039] Figure 6 The sintering morphology of the pure silicon carbide support shown in Comparative Example 1 at low temperature;

[0040] Figure 7SEM image of pure silicon carbide micro-reactor shown in Comparative Example 2;

[0041] Figure 8 Degradation effect of ozone catalyzed by pure silicon carbide micro-reactor shown in Comparative Example 2 on dyes;

[0042] Figure 9 Degradation effect of ozone on dyes shown in Comparative Example 3.

[0043] Legend of the figure:

[0044] 1-ozone generator, 2-ball valve, 3-flow meter, 4-ozone detector, 5-waste water storage tank, 6-upflow reactor tower, 7-silicon carbide micro-reactor, 8-vacuum pump. DETAILED DESCRIPTION

[0045] The application will be described in greater detail with reference to the accompanying drawings and specific embodiments. The embodiments are implemented on the premise of the technical solutions of the application, and detailed implementation modes and specific operation processes are given, but the protection scope of the application is not limited to the following examples. All other examples obtained by those skilled in the art on the premise that no creative labor is made based on the given examples belong to the scope of protection of the present application.

[0046] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present application are conventional reagents, methods, instruments and equipment in the art.

[0047] In the following examples, the cobalt oxide nanoparticles (CAS No. 1308-06-1) used were purchased from Alfa Aesar (China) Chemical Co., Ltd.; polyvinyl alcohol (CAS No. 9002-89-5) was purchased from Shanghai Huake Industry Co., Ltd.; tetramethylammonium hydroxide (CAS No. 75-59-2) was purchased from Alfa Aesar (China) Chemical Co., Ltd.; ethanol (CAS No. 64-17-5) was purchased from Alfa Aesar (China) Chemical Co., Ltd.; silicon carbide powder (CAS No. 409-21-2) was purchased from Zhejiang Carbonbang Technology Co., Ltd.; Congo red (CAS No. 573-58-0) was purchased from Shanghai Yuanye Biotechnology Co., Ltd.; Chrome Black T (CAS No. 1787-61-7) was purchased from Shanghai Melin Biological Technology Co., Ltd.; Reactive Red 195 (CAS No. 93050-79-4) was purchased from Shanghai Melin Biological Technology Co., Ltd.; Reactive Brilliant Blue Kn-R (CAS No. 2580-78-1); Indigo (CAS No. 482-89-3); Acid Blue (CAS No. 27360-85-6) were all purchased from Shanghai Aldrin Biological Technology Co., Ltd.

[0048] Example 1

[0049] A method for preparing a silicon carbide micro-reactor for ozone catalysis, comprising weighing 35 g of silicon carbide powder, 5 g of cobalt oxide nanoparticles, 8 g of a polyvinyl alcohol aqueous solution with a concentration of 8wt%, 2 g of a tetramethylammonium hydroxide aqueous solution with a concentration of 5wt%, 50 g of ethanol, and 50 g of ball milling balls in a ball milling jar, and placing them in a planetary ball mill for ball milling for 5 h. The obtained slurry is subjected to dry pressing at a pressure of 30 MPa, and after drying at room temperature for 12 h, subjected to secondary dry pressing at a pressure of 50 MPa to obtain a green body. After drying the green body, it is placed in a graphite furnace for pressureless sintering in an argon atmosphere, and the sintering program is as follows: first, increase the temperature to 850℃ at a rate of 3℃ / min, and keep the temperature for 2 h; then increase the temperature to 1400℃ at a rate of 3℃ / min, and keep the temperature for 2 h; after the temperature keeping is completed, naturally cool the furnace to room temperature, and obtain a silicon carbide micro-reactor 7.

[0050] At room temperature, the prepared micro-reactor 7 is characterized and evaluated for dye degradation performance

[0051] Characterization method 1: the apparent morphology of the micro-reactor is characterized by a scanning electron microscope.

[0052] The results show that the micro-reactor has a large number of sintering necks of cobalt oxide Figure 1 and Figure 2 A).

[0053] Characterization method 2: the contact angle of the micro-reactor is measured by a contact angle measuring instrument.

[0054] The results show that the contact angle of the micro-reactor is 10° Figure 3 A), showing hydrophilic properties.

[0055] Characterization method 3: the pore size of the micro-reactor is measured by a mercury porosimeter, and the compressive strength of the micro-reactor is tested by a strength tester.

[0056] The results show that the most probable pore size of the micro-reactor is 4.36 μm, and the compressive strength is 45.73 MPa (Table 1).

[0057] Test method 1: evaluate the dye degradation performance of the micro-reactor.

[0058] A water treatment system for ozone catalysis, the silicon carbide micro-reactor 7 is loaded in an upflow reaction tower 6. The water treatment system comprises:

[0059] a wastewater storage tank 5 connected with the upflow reaction tower 6 and used for storing wastewater to be treated;

[0060] and an ozone generator 1 connected with the upflow reaction tower 6, used for passing the generated ozone into the upflow reaction tower 6 for catalysis, and the ozone generator 1 is connected with the bottom of the upflow reaction tower 6.

[0061] In this embodiment, the ozone generator 1 is connected with the pipeline of the up-flow reactor tower 6, and a ball valve 2, a flow meter 3 and an ozone detector 4 are also connected in the pipeline.

[0062] In this embodiment, the water treatment system further comprises a vacuum pump 8 for recycling the treated effluent into the wastewater storage tank, and the vacuum pump 8 is connected with the top of the up-flow reactor tower 6.

[0063] As shown in Figure 4 The prepared silicon carbide micro-reactor 7 is placed in the up-flow reactor tower 6, and a Congo red solution with a concentration of 100 mg / L is prepared in the wastewater storage tank 5. The ozone generator 1, the ball valve 2, the flow meter 3 and the ozone detector 4 are connected, the outlet of the ozone detector 4 is connected with the lower part of the up-flow reactor tower 6, the ozone is catalytically treated in situ to mix with the dye wastewater, the ozone catalytically treated effluent is recycled into the wastewater storage tank 5 through the vacuum pump 8 at the upper end of the up-flow reactor tower 6, and the sample is taken at a certain time interval, the absorbance of the Congo red dye at the maximum absorption wavelength is tested, and the degradation rate of the dye is calculated. The results show that the silicon carbide micro-reactor 7 can efficiently catalyze the degradation of the organic dye Congo red by ozone, and the dye can be almost 100% degraded within 120 min. Figure 5 A).

[0064] Example 2

[0065] A method for preparing a silicon carbide micro-reactor for ozone catalysis, wherein the content of cobalt oxide is changed compared to example 1, and other conditions remain unchanged. That is:

[0066] 30 g of silicon carbide powder, 10 g of cobalt oxide nanoparticles, 8 g of polyvinyl alcohol solution with a concentration of 8wt%, 2 g of tetramethylammonium hydroxide solution with a concentration of 5wt%, 50 g of ethanol and 50 g of ball milling balls are weighed in a ball milling jar, and then placed in a planetary ball mill for ball milling for 5 h to obtain a green body paste. After drying the green body, it is placed in a graphite furnace for pressureless sintering under an argon atmosphere, and the sintering program is as follows: first, increase the temperature to 850℃ at a rate of 3℃ / min and keep for 2 h, then increase the temperature to 1400℃ at a rate of 3℃ / min and keep for 2 h; after the end of the holding period, the furnace is naturally cooled to room temperature, and a silicon carbide micro-reactor 7 is obtained.

[0067] At room temperature, the prepared micro-reactor is characterized and evaluated for dye degradation performance.

[0068] Characterization method 1: scanning electron microscopy is used to characterize the apparent morphology of the micro-reactor.

[0069] The results show that the micro-reactor has a large amount of sintering necks of cobalt oxide Figure 2 B).

[0070] Characterization means 2: the contact angle of the microreactor is tested by a contact angle measuring instrument.

[0071] The results show that the contact angle of the microreactor can reach 5° (B) in an instant, showing superhydrophilic properties. Figure 3 B).

[0072] Characterization means 3: the pore size of the microreactor is measured by a mercury porosimeter, and the compressive strength of the microreactor is tested by a strength tester.

[0073] The results show that the most probable pore size of the microreactor is 3.65 μm, and the compressive strength is 43.57 MPa (Table 1).

[0074] Test method 1: the degradation performance of the silicon carbide microreactor 7 of Example 2 on dyes is evaluated. The test is carried out by using a water treatment system, most of which is the same as the water treatment system in Example 1, except that the silicon carbide microreactor 7 in Example 2 is replaced by the silicon carbide microreactor 7 in Example 2. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of organic dye Congo red by ozone, and can degrade the dye by nearly 100% within 80 min (B). Figure 5 B).

[0075] Example 3

[0076] A method for preparing a silicon carbide microreactor for ozone catalysis, wherein the rest of the conditions are the same as in Example 1, and only the cobalt oxide content is changed. That is:

[0077] 25 g of silicon carbide powder, 15 g of cobalt oxide nanoparticles, 8 g of polyvinyl alcohol aqueous solution with a concentration of 8wt%, 2 g of tetramethylammonium hydroxide aqueous solution with a concentration of 5wt%, 50 g of ethanol, and 50 g of ball milling small balls are weighed in a ball milling jar, and then placed in a planetary ball mill for ball milling for 5 h to obtain a green body paste. After drying the body, it is placed in a graphite furnace for pressureless sintering under an argon atmosphere, and the sintering program is as follows: first, increase the temperature to 850°C at a rate of 3°C / min, and keep it for 2 h, then increase the temperature to 1400°C at a rate of 3°C / min, and keep it for 2 h; after the holding is completed, the furnace is naturally cooled to room temperature, and the silicon carbide microreactor 7 is obtained.

[0078] At room temperature, the prepared microreactor is characterized and evaluated for dye degradation performance.

[0079] Characterization means 1: the apparent morphology of the microreactor is characterized by a scanning electron microscope.

[0080] The results show that the microreactor has a large amount of cobalt oxide in the form of sintering necks (C). Figure 2 C).

[0081] Characterization means 2: the contact angle of the microreactor is tested by a contact angle measuring instrument.

[0082] The results show that the contact angle of the microreactor reaches 0° (instantaneously) Figure 3 C), showing superhydrophilic properties.

[0083] Characterization means 3: The pore size of the microreactor is measured by a mercury porosimeter, and the compressive strength of the microreactor is tested by a strength tester.

[0084] The results show that the most probable pore size of the microreactor is 3.24 μm, and the compressive strength is 42.68 MPa (Table 1).

[0085] Test method 1: Evaluate the degradation performance of the silicon carbide ozone microreactor 7 of Example 3 on dyes. The test is carried out by using a water treatment system, most of which is the same as the water treatment system in Example 1, except that the silicon carbide microreactor 7 is replaced by the silicon carbide microreactor 7 in Example 3. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of organic dye Congo red by ozone, and can degrade the dye by nearly 100% within 60 min Figure 5 C). But compared with Example 2, the degradation effect of the two is very small, but the concentration of cobalt oxide used in Example 3 is higher, indicating that the concentration of cobalt oxide in Example 2 can be considered as the optimal.

[0086] Example 4

[0087] A method for preparing a silicon carbide microreactor for ozone catalysis, compared with Example 1, all other conditions remain unchanged, only the green body sintering procedure is changed. That is:

[0088] After the green body is dried, it is placed in a graphite furnace for pressureless sintering under an argon atmosphere. The sintering procedure is: first, increase the temperature to 800°C at a rate of 2°C / min and keep it for 2 hours, then increase the temperature to 1200°C at a rate of 2°C / min and keep it for 2 hours; after the holding period is over, naturally cool the furnace to room temperature, and obtain the silicon carbide microreactor 7.

[0089] At room temperature, the pore size of the microreactor is measured by a mercury porosimeter, and the compressive strength of the microreactor is tested by a strength tester.

[0090] The results show that the most probable pore size of the microreactor is 3.85 μm, and the compressive strength is 44.38 MPa (Table 1).

[0091] Example 5

[0092] A method for preparing a silicon carbide microreactor for ozone catalysis, compared with Example 1, all other conditions remain unchanged, only the green body sintering procedure is changed, and finally the silicon carbide microreactor 7 is obtained. That is:

[0093] After the green body is dried, the green body is placed into a graphite furnace for pressureless sintering under an argon atmosphere. The sintering procedure is as follows: first, the temperature is raised to 900 °C at a rate of 5 °C / min, and then the temperature is kept at 900 °C for 2 h; then, the temperature is raised to 1500 °C at a rate of 5 °C / min, and then the temperature is kept at 1500 °C for 2 h; after the temperature keeping is completed, the furnace is naturally cooled to room temperature, and a silicon carbide catalytic microreactor 7 is obtained.

[0094] At room temperature, the pore size of the microreactor is measured by using a mercury injection apparatus, and the compressive strength of the microreactor is measured by using a strength tester.

[0095] The results show that the most probable pore size of the microreactor is 3.36 μm, and the compressive strength is 45.63 MPa (Table 1).

[0096] Example 6

[0097] The application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions are unchanged, only the type of dye is changed, that is:

[0098] A chromium black T solution with a concentration of 100 mg / L is prepared, and the water treatment system loaded with the silicon carbide microreactor 7 of Example 1 is used to degrade the solution. The absorbance of the chromium black T dye at the maximum absorption wavelength is measured at certain time intervals, and the degradation rate of the dye is calculated. The results show that the silicon carbide microreactor can efficiently catalyze the degradation of the organic dye chromium black T by ozone, and the dye can be almost 100% degraded in 40 min. Figure 5 D).

[0099] Example 7

[0100] The application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions are unchanged, only the type of dye is changed, that is:

[0101] A reactive red 195 solution with a concentration of 100 mg / L is prepared, and the water treatment system loaded with the silicon carbide microreactor 7 of Example 1 is used to degrade the solution. The absorbance of the reactive red 195 dye at the maximum absorption wavelength is measured at certain time intervals, and the degradation rate of the dye is calculated. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of the organic dye reactive red 195 by ozone, and the dye can be almost 100% degraded in 80 min. Figure 5 E).

[0102] Example 8

[0103] The application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions are unchanged, only the type of dye is changed, that is:

[0104] A solution of Acid Orange 52 II with a concentration of 100 mg / L was prepared and degraded by the water treatment system of Example 1 filled with the silicon carbide microreactor 7. The silicon carbide microreactor 7 was sampled at certain time intervals, the absorbance of the Acid Orange 52 II dye at the maximum absorption wavelength was tested, and the degradation rate of the dye was calculated. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of the organic dye Acid Orange 52 II by ozone, and the dye can be almost 100% degraded within 60 min. Figure 5 F}.

[0105] Example 9

[0106] An application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions remain unchanged, only the type of dye is changed, that is:

[0107] A solution of Reactive Brilliant Blue Kn-R with a concentration of 100 mg / L was prepared and degraded by the water treatment system of Example 1 filled with the silicon carbide microreactor 7. The silicon carbide microreactor 7 was sampled at certain time intervals, the absorbance of the Reactive Brilliant Blue Kn-R dye at the maximum absorption wavelength was tested, and the degradation rate of the dye was calculated. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of the organic dye Reactive Brilliant Blue Kn-R by ozone, and the dye can be almost 100% degraded within 60 min. Figure 5 G}.

[0108] Example 10

[0109] An application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions remain unchanged, only the type of dye is changed, that is:

[0110] A solution of indigo with a concentration of 100 mg / L was prepared and degraded by the water treatment system of Example 1 filled with the silicon carbide microreactor 7. The silicon carbide microreactor was sampled at certain time intervals, the absorbance of the indigo dye at the maximum absorption wavelength was tested, and the degradation rate of the dye was calculated. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of the organic dye indigo by ozone, and the dye can be almost 100% degraded within 60 min. Figure 5 H}.

[0111] Example 11

[0112] An application of the silicon carbide microreactor for ozone catalysis to degrade dyes, compared with Example 1, the rest of the conditions remain unchanged, only the type of dye is changed, that is:

[0113] A solution of acid blue with concentration of 100 mg / L was prepared and degraded by the water treatment system filled with silicon carbide microreactor 7 of Example 1. The silicon carbide microreactor was sampled at certain time intervals, and the absorbance of acid blue dye at the maximum absorption wavelength was tested to calculate the degradation rate of the dye. The results show that the silicon carbide microreactor 7 can efficiently catalyze the degradation of organic dye acid blue by ozone, and can degrade the dye by nearly 100% within 60 min.

[0114] Comparative Example 1

[0115] Compared with Example 1, the rest of the conditions remain unchanged, but no metal oxide is added. That is:

[0116] 40 g of silicon carbide powder, 8 g of polyvinyl alcohol aqueous solution with a concentration of 8wt%, 2 g of tetramethylammonium hydroxide aqueous solution with a concentration of 5wt%, 50 g of ethanol as a ball milling dispersion liquid, and 50 g of ball milling balls were weighed into a ball milling tank and placed in a planetary ball mill for ball milling for 5 h. The obtained mud was dry pressed under a pressure of 30 MPa, and after drying at room temperature for 12 h, it was dry pressed again under a pressure of 50 MPa to obtain a green body. After drying, the green body was placed in a graphite furnace for pressureless sintering under an argon atmosphere. The sintering program was: first, increase the temperature to 850°C at a rate of 3°C / min and keep it for 2 h, then increase the temperature to 1400°C at a rate of 3°C / min and keep it for 2 h; after the holding period, the furnace was naturally cooled to room temperature, and a pure silicon carbide support was obtained.

[0117] At room temperature, the apparent morphology of the prepared microreactor was photographed.

[0118] The results show that at low temperature, the pure silicon carbide support without cobalt oxide nanoparticles cannot be effectively sintered, and the powder can be easily wiped off by gently touching it with the hand Figure 6 .

[0119] Comparative Example 2

[0120] Compared with Example 1, the rest of the conditions remain unchanged, but no metal oxide is added to make the catalyst sintering neck structure not appear, and the sintering temperature is changed. That is

[0121] Weigh 40 g of silicon carbide powder, 8 g of 8wt% polyvinyl alcohol aqueous solution and 2 g of 5wt% tetramethylammonium hydroxide aqueous solution, 50 g of ethanol as a ball milling dispersion liquid, 50 g of ball milling balls in a ball milling tank, and place it in a planetary ball mill for ball milling for 5 h to obtain a slurry. The obtained slurry is dry-pressed under a pressure of 30 MPa, and after drying at room temperature for 12 h, it is dry-pressed again under a pressure of 50 MPa to obtain a green body. After drying the green body, it is placed in a graphite furnace for pressureless sintering under an argon atmosphere. The sintering procedure is as follows: first, increase the temperature to 850℃ at a rate of 3℃ / min, and keep it for 2 h; then increase the temperature to 1900℃ at a rate of 3℃ / min, and keep it for 2 h; after the end of the holding period, naturally cool the furnace to room temperature; and a micro-reactor is obtained.

[0122] At room temperature, the micro-reactor morphology is characterized by a scanning electron microscope.

[0123] The results show that after high-temperature sintering, the film morphology is complete, but without the addition of cobalt oxide nanoparticles, there is no formation of cobalt oxide sintering necks between pure silicon carbide particles, but compared with Examples 1-3, high-temperature sintering makes the silicon carbide particle morphology tend to be round Figure 7 )

[0124] Test Method 1: Evaluate the dye degradation performance of the micro-reactor of Comparative Example 2. The results show that the degradation rate of the pure silicon carbide micro-reactor to the dye is 80% within 120 min, but compared with Example 2, the degradation effect of Comparative Example 2 on Congo red dye is limited, indicating that pure silicon carbide cannot effectively catalyze the production of reactive oxygen species by ozone Figure 8 ).

[0125] Comparative Example 3

[0126] Compared with Example 1, the remaining conditions are unchanged, and the carbonized silicon micro-reactor 7 in Example 1 is not used for catalysis, i.e.

[0127] The water treatment system is tested, most of which is the same as the water treatment system in Example 1, except that the carbonized silicon micro-reactor 7 is not loaded. Directly mix ozone with dye, sample at certain time intervals, test the absorbance of Congo red dye at the maximum absorption wavelength, calculate the degradation rate of the dye, and investigate the degradation effect of ozone direct oxidation on the dye. The results show that the degradation rate of the water treatment system to Congo red dye is 80% within 120 min, which is basically the same as that of Comparative Example 2, further indicating that the pure silicon carbide in Comparative Example 2 cannot effectively catalyze the production of reactive oxygen species by ozone Figure 9 ).

[0128] Table 1 is the pore size, porosity and compressive strength test performance of the silicon carbide micro-reactor of each example.

[0129] Table 1 Performance of Silicon Carbide Micro-Reactor

[0130]

[0131] While the application has been described in detail and with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof. It is therefore intended that whatever lies within the scope of the application be covered by the appended claims and that there be no intent of any sort to limit the application except as can be explicitly expressed in those claims.

Claims

1. A method for preparing a silicon carbide microreactor for ozone catalysis, characterized in that, Includes the following steps: S1. Silicon carbide powder, metal oxide, binder and dispersant are placed in a solvent, mixed and ball-milled to obtain a slurry, and dried to form a mud. The metal oxide includes one or more of zinc oxide, cobalt oxide, iron oxide, manganese oxide, nickel oxide and cerium oxide. S2. The obtained clay is molded in a mold to obtain a blank; S3. The obtained green body is sintered in an inert gas atmosphere and cooled to obtain a silicon carbide microreactor, and the reaction is completed. In step S3, the specific sintering process is as follows: the temperature is increased to 800~900℃ at a rate of 2-5℃ / min and held for 1~3 hours, then increased to 1200~1500℃ at a rate of 2~5℃ / min and held for 1~3 hours.

2. The method for preparing a silicon carbide microreactor for ozone catalysis according to claim 1, characterized in that, In step S1, the adhesive includes one or more of polyethylene glycol, polyvinyl alcohol, hydroxypropyl methylcellulose, carboxymethyl cellulose, carboxyethyl cellulose, and polyacrylic acid; The dispersant includes one or more of tetramethylammonium hydroxide, sodium polyacrylate, ammonium polyacrylate, polycarbonate, polyethyleneimine, sodium alginate, and ammonium polymethacrylate; The solvent includes ethanol or water.

3. The method for preparing a silicon carbide microreactor for ozone catalysis according to claim 1, characterized in that, In step S1, the mass ratio of silicon carbide powder, metal oxide, binder, dispersant and solvent is (10-15):(2-10):(1-5):(0.8-2):(20-30).

4. The method for preparing a silicon carbide microreactor for ozone catalysis according to claim 1, characterized in that, In step S1, the average particle size of the silicon carbide powder is 10~20 μm; The average particle size of the metal oxide is 0.1~2 μm.

5. The method for preparing a silicon carbide microreactor for ozone catalysis according to claim 1, characterized in that, In step S2, the specific molding process is as follows: the obtained clay is dry-pressed under a pressure of 20~40 MPa, dried at room temperature for 6~24 h, and then dry-pressed again under a pressure of 40~70 MPa to obtain a green body.

6. A silicon carbide microreactor for ozone catalysis, which is prepared by any one of the preparation methods described in claims 1 to 5, wherein a catalytically functional metal oxide serves as a sintering neck to bind silicon carbide particles together, forming a structure with a three-dimensional interconnected network.

7. A silicon carbide microreactor for ozone catalysis according to claim 6, characterized in that, The most probable pore size of the silicon carbide microreactor is 1~5 μm, and the porosity is 60%~80%.

8. The application of the silicon carbide microreactor for ozone catalysis as described in claim 6 in the field of water treatment, characterized in that, The silicon carbide microreactor is used to treat wastewater containing any one of the following dyes: Congo Red, Chrome Black T, Reactive Red 195, Reactive Brilliant Blue KN-R, Indigo, Acid Blue, and Acid Orange II.

9. A water treatment system for ozone catalysis, characterized in that, The silicon carbide microreactor of claim 6 is packed into an upflow reaction tower.

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