Preparation method of manganese ferrite-diatomic sewage treatment catalyst and application thereof

Abstract

The application discloses a preparation method of a manganese ferrite-diatomic sewage treatment catalyst and application thereof, and comprises the following steps: (1) diatomic is immersed in nitric acid for treatment, and then manganese oxide and iron oxide are added; then, lye is added to adjust the system to be alkaline, and modified diatomic mixed solution is obtained; (2) tetraethyl titanate is added to the mixed solution for hydrothermal reaction, and then the solid product is separated, and a precursor is obtained; (3) the precursor, zinc acetate and water are uniformly mixed, dried to remove water, and then calcined in a protective atmosphere; after the completion of the calcination, the calcined product is cooled to room temperature, heated and reduced in a hydrogen atmosphere, and then cooled to room temperature; the product is washed and dried, and the catalyst is obtained. The catalyst has good catalytic activity, can efficiently degrade BPA and other organic pollutants in wastewater, and can be efficiently separated and recovered from the wastewater.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, in particular to a preparation method of a manganese ferrite-diatomite sewage treatment catalyst and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art already known to a person of ordinary skill in the art.

[0003] Bisphenol A (BPA) is a typical endocrine-disrupting compound (EDC) with the characteristics of persistent and difficult to degrade, and is a necessary material for the synthesis of polycarbonate plastics and epoxy resins. The industrial wastewater of related enterprises often contains a high concentration of BPA. Bisphenol A can directly enter the water body through industrial production discharge wastewater, or indirectly enter the water body through soil, landfill leachate, wastewater sludge and other ways contaminated by bisphenol A. At present, bisphenol A is detected in water sources and drinking water all over the world. Studies have shown that bisphenol A has hormone-like activity, and long-term exposure to bisphenol A environment may cause reproductive system disorders, metabolic abnormalities and feminization trends in humans and other organisms, causing serious harm to the normal growth and metabolism of organisms.

[0004] At present, the removal technology of BPA in water mainly includes adsorption method, biological method and advanced oxidation method, etc. Among them, the adsorption method, which removes BPA through physical adsorption of porous materials, generally has the problems of limited adsorption capacity and the need for regeneration of materials. The biological method uses microorganisms to metabolically degrade BPA, but has the disadvantages of long treatment period and sensitivity to water quality conditions. The traditional advanced oxidation method based on hydroxyl radicals has the defects of difficult separation of catalyst, need for acidic conditions and easy generation of secondary pollution. The advanced oxidation technology based on sulfate radicals has the characteristics of strong oxidation ability and wide pH range, but it needs the catalytic effect of catalyst to release sulfate radicals, and the traditional heterogeneous catalysts face the problems of low catalytic activity leading to limited degradation effect and difficult separation and recovery. SUMMARY

[0005] In view of the above problems, the present application provides a preparation method of a manganese ferrite-diatomite sewage treatment catalyst and application thereof, which not only has good catalytic activity and can efficiently degrade BPA and other organic pollutants in wastewater, but also can be efficiently separated and recovered from wastewater. Specifically, the technical scheme of the present application is as follows.

[0006] Firstly, the application provides a preparation method of a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0007] (1) The diatomite is immersed in nitric acid for treatment, and after completion, manganese oxide and iron oxide are added according to a molar ratio of Mn:Fe = 1:2-2.05 to convert residual nitric acid into manganese nitrate and iron nitrate. Then, an alkali solution is added to adjust the system to be alkaline, and a modified diatomite mixture is obtained.

[0008] (2) Tetraethyl titanate is added to the modified diatomite mixture and mixed, and then a hydrothermal reaction is performed, and after completion, a solid product is separated to obtain a precursor.

[0009] (3) The precursor, zinc acetate and water are mixed, dried to remove water, and then calcined in a protective atmosphere. After completion, it is cooled to room temperature, and the calcined product is heated and reduced in a hydrogen atmosphere, and after completion, it is cooled to room temperature, washed and dried to obtain the catalyst.

[0010] Further, in step (1), the ratio of diatomite to nitric acid is 1g:7-12mL. Optionally, the concentration of the nitric acid is 2-5mol / L.

[0011] Further, in step (1), the immersion time is 40-60min.

[0012] Further, in step (1), the pH of the system is adjusted to 10-12 by the alkali solution. Optionally, the alkali solution includes at least one of sodium hydroxide solution, potassium hydroxide solution, ammonia water, etc.

[0013] Further, in step (2), the tetraethyl titanate is 14-20% of the mass of diatomite.

[0014] Further, in step (2), the temperature of the hydrothermal reaction is 190-230℃, and the reaction time is 11-15 hours.

[0015] Further, in step (3), the ratio of the precursor, water is 1g:0.2-0.35g:5-10mL. Optionally, the Zn 2+ source includes at least one of zinc chloride, zinc sulfate, zinc nitrate, zinc acetate, etc.

[0016] Further, in step (3), the drying temperature is 80-110℃, and the solid product is dried at this temperature until the mass no longer changes.

[0017] Further, in step (3), the calcination temperature is 400~450℃, and the time is 1.5~2 hours. Optionally, the protective atmosphere includes at least one of nitrogen, argon, etc.

[0018] Furthermore, in step (3), the heating temperature of the reduction treatment is 500~600℃, and the time is 1~2 hours.

[0019] Secondly, this invention provides the application of a manganese ferrite-diatomite wastewater treatment catalyst in wastewater purification. Preferably, persulfate (PMS) is added to the wastewater during purification.

[0020] Further, the amount of persulfate added to the wastewater is 0.02~0.04 g / L. Optionally, the persulfate includes at least one of sodium persulfate, potassium persulfate, etc.

[0021] Furthermore, the amount of catalyst added to the wastewater is 0.7~1.3 g / L.

[0022] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0023] This invention first employs nitric acid to impregnate diatomaceous earth, which dissolves impurities in the pores of the diatomaceous earth, improves pore connectivity, and helps increase the loading of active catalytic components. This also helps increase the capacity for organic pollutants in wastewater during degradation, accelerating the degradation rate. Furthermore, this invention utilizes manganese oxide and iron oxide to not only eliminate residual nitric acid but also convert it into manganese ferrite, a component used in the synthesis of the active catalytic component. The raw material, spinel, achieves the efficient utilization and conversion of nitric acid. Then, this invention adjusts the above-treated diatomaceous earth to alkalinity and adds tetraethyl titanate, which not only forms a raw material for synthesis... The required iron and manganese hydroxides, and also for the formation of the tetraethyl titanate. Provides hydrolysis conditions to facilitate the formation of supported active catalytic components through subsequent hydrothermal reactions. Spinel and The catalyst precursor. Furthermore, this invention uses Zn element to modify the precursor at high temperature, on the one hand utilizing the Zn element to... Diffusion in the crystal lattice replaces some of the Mn and Fe atoms, increasing the lattice energy and thus improving the crystal structure. Electron transfer between PMS and the PMS crystals allows for more efficient catalysis of PMS to generate sulfate and hydroxyl radicals, thus enhancing the oxidative degradation of organic pollutants such as BPA in wastewater. Furthermore, the diffusion of Zn and the replaced Mn and Fe into the TiO2 lattice enables synergistic modification, improving… The response ability to visible light enables the catalyst of the present application to degrade organic matters in sewage by using visible light, so that the catalyst of the present application has the ability of multiple synergistic purification of sewage, which is not only high in efficiency and good in purification effect, but also low in cost. The superparamagnetism enables the catalyst of the present application to be quickly separated and recovered by an external magnetic field, thereby reducing the operation cost. After the residual is converted into an element by heating reduction treatment of the calcined product with alkali liquor, the active catalytic component loaded on diatomite is fixed by using the element, thereby reducing the falling-off and increasing the service life of the catalyst. In addition, the existence of the element can also facilitate the regeneration of the catalyst. When the catalytic ability of the catalyst is decreased, the zinc atom provided by the element can diffuse into the crystal lattice of the active catalytic component by heat treatment, which is helpful to improve the catalytic ability. BRIEF DESCRIPTION OF DRAWINGS

[0024] The drawings constituting a part of the specification of the present application are used to provide further understanding of the present application and do not constitute improper limitation of the present application.

[0025] Figure 1 The catalyst sample chart prepared for the following Example 1.

[0026] Figure 2 The degradation performance test chart of the catalyst prepared for the following Example 1.

[0027] Figure 3 The catalyst sample chart prepared for the following Example 2.

[0028] Figure 4 The degradation performance test chart of the catalyst prepared for the following Example 2.

[0029] Figure 5 The catalyst sample chart prepared for the following Example 3.

[0030] Figure 6 The catalyst sample chart prepared for the following Example 4.

[0031] Figure 7 The catalyst sample chart prepared for the following Example 5.

[0032] Figure 8 The catalyst sample chart prepared for the following Example 6. DETAILED DESCRIPTION

[0033] The present application will be further described below in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. The experimental methods not specified in the following examples are usually carried out according to the conventional conditions or the conditions suggested by the manufacturers.

[0034] Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as commonly understood by one of ordinary skill in the art. The reagents or materials used in the present application can be purchased through conventional routes, and unless otherwise specified, the reagents or materials used in the present application are used according to the conventional manner in the art or according to the product instructions. In addition, any method and material similar or equivalent to those described can be applied in the method of the present application. The technical solutions of the present application are further described in conjunction with the drawings and specific examples of the present application.

[0035] Example 1

[0036] A preparation method of a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0037] (1) Diatomite with fineness of 200 mesh is mixed with 4 mol / L nitric acid in a proportion of 1 g:10 mL, and then stirred uniformly, and then immersed for 50 min. After completion, manganese oxide and iron oxide are added according to the molar ratio of Mn:Fe=1:2 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then, ammonia water is added to adjust the pH of the system to 12 to obtain a modified diatomite mixture.

[0038] (2) Tetraethyl titanate with a mass of 18% of the diatomite is added to the modified diatomite mixture, and after stirring uniformly, a hydrothermal reaction is carried out in a reaction kettle (temperature is 200°C, time is 12 hours). After completion, the solid product is filtered out to obtain a precursor.

[0039] (3) The precursor, zinc nitrate, and water are mixed in a proportion of 1 g:0.3 g:7 mL, and then stirred uniformly, and then dried at 100°C until the mass of the solid product no longer changes. Then, the solid product is transferred to a box furnace (the protective atmosphere is nitrogen), and heated to 400°C at a heating rate of 3°C / min, and calcined for 2 h. After completion, it is cooled to room temperature, and then the obtained calcined product is subjected to reduction treatment in a hydrogen atmosphere (temperature is 520°C, time is 1.5 hours). After completion, it is cooled to room temperature, and then washed with clean water and dried to obtain the catalyst, as shown in Figure 1 .

[0040] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (the initial concentration of the two pollutants is 10 mg / L) is placed in a beaker, and then the catalyst prepared in the present example is added to the solution in a proportion of 1.0 g / L, and stirred magnetically for 1 min (as Figure 2The degradation rate of bisphenol A and rhodamine B was tested after the 10th recycling of the catalyst. The results were as follows: the degradation rate of bisphenol A was 97.26%, and the degradation rate of rhodamine B was 95.44%.

[0041] Example 2

[0042] A method for preparing a manganese ferrite-diatomite wastewater treatment catalyst includes the following steps:

[0043] (1) Diatomite with a fineness of 200 mesh was mixed with 2 mol / L nitric acid at a ratio of 1 g: 12 mL, and then stirred uniformly, and then immersed for 40 min. After completion, manganese oxide and iron oxide were added at a molar ratio of Mn:Fe = 1:2 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then, sodium hydroxide solution was added to adjust the pH of the system to 10 to obtain a modified diatomite mixture.

[0044] (2) Tetraethyl titanate was added to the modified diatomite mixture at a ratio of 20% of the mass of diatomite, and then stirred uniformly, and then subjected to hydrothermal reaction in a reaction kettle (temperature 190°C, time 15 hours). After completion, the solid product was filtered out to obtain a precursor.

[0045] (3) The precursor, zinc acetate, and water were mixed at a ratio of 1 g: 0.35 g: 10 mL, and then stirred uniformly, and then dried at 80°C until the mass of the solid product no longer changed. Then, the solid product was transferred to a box furnace (the protective atmosphere was nitrogen), and then heated at a rate of 5°C / min to 450°C and calcined for 1.5 h. After completion, it was cooled to room temperature, and then the obtained calcined product was subjected to reduction treatment in a hydrogen atmosphere (temperature 600°C, time 1 hour). After completion, it was cooled to room temperature, washed with clean water, and then dried to obtain the catalyst, as shown in Figure 3 .

[0046] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (the initial concentration of the two pollutants was 10 mg / L) was taken in a beaker, and then the catalyst prepared in this example was added to the solution at a ratio of 0.7 g / L, and then stirred magnetically for 1 min (as shown in Figure 4The solution was irradiated with sunlight (power 40 W) at a distance of 30 cm from the liquid surface in the beaker. The catalyst was separated by an external magnetic field at t = 20 min to obtain the first recovered catalyst. The degradation rates of bisphenol A and rhodamine B were calculated according to the above method. The results were as follows: the degradation rate of bisphenol A was 97.26%, and the degradation rate of rhodamine B was 95.44%.

[0047] Example 3

[0048] A preparation method of a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0049] (1) Diatomite with a fineness of 200 mesh was mixed with 5 mol / L nitric acid at a ratio of 1 g:7 mL, and then stirred uniformly, and then immersed for 60 min. After completion, manganese oxide and iron oxide were added according to a molar ratio of Mn:Fe=1:2.05 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then, ammonia water was added to adjust the pH of the system to 11 to obtain a modified diatomite mixture.

[0050] (2) Tetraethyl titanate was added to the modified diatomite mixture at a mass fraction of 14% of diatomite, and then stirred uniformly, and then subjected to hydrothermal reaction in a reaction kettle (temperature 230°C, time 11 hours). After completion, the solid product was filtered out to obtain a precursor.

[0051] (3) The precursor, zinc sulfate, and water were mixed at a ratio of 1 g:0.2 g:5 mL, and then stirred uniformly, and then dried at 110°C until the mass of the solid product no longer changed. Then, the solid product was transferred to a box furnace (protective atmosphere nitrogen), and heated to 450°C at a heating rate of 5°C / min, and calcined for 1.5 h. After completion, it was cooled to room temperature, and then the obtained calcined product was subjected to reduction treatment in a hydrogen atmosphere (temperature 500°C, time 2 hours). After completion, it was cooled to room temperature, washed with clean water, and then dried to obtain the catalyst, as shown in Figure 5 .

[0052] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (both pollutants have an initial concentration of 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 1.3 g / L, and stirred magnetically for 1 min, then 0.04 g / L of sodium persulfate was added and stirred uniformly, while the beaker was irradiated with sunlight with a power of 40 W, 30 cm away from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst according to the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method is the same as in Example 1 above). The results are: bisphenol A degradation rate = 97.26%, rhodamine B degradation rate = 95.44%.

[0053] Example 4

[0054] A method for preparing a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0055] (1) Diatomite with a fineness of 200 mesh was mixed with 4 mol / L nitric acid at a ratio of 1 g: 10 mL and stirred uniformly, then immersed for 50 min. After completion, manganese oxide and iron oxide were added at a molar ratio of Mn: Fe = 1:2 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then ammonia water was added to adjust the pH of the system to 12 to obtain a modified diatomite mixture.

[0056] (2) Tetraethyl titanate was added to the modified diatomite mixture at a mass fraction of 18% of diatomite, and after stirring uniformly, a hydrothermal reaction was carried out in a reaction kettle (temperature 200°C, time 12 hours). After completion, the solid product was filtered out to obtain a precursor.

[0057] (3) The precursor was mixed with water at a ratio of 1 g: 7 mL and stirred uniformly, then dried at 100°C until the mass of the solid product no longer changed. The solid product was then transferred to a box furnace (with nitrogen as the protective atmosphere), and heated at a rate of 3°C / min to 400°C and calcined for 2 h. After completion, the product was cooled to room temperature, washed with clean water and dried to obtain the catalyst, as shown in Figure 6 .

[0058] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (both pollutants have an initial concentration of 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 1.0 g / L, and stirred magnetically for 1 min, then 0.03 g / L of sodium persulfate was added and stirred uniformly, while the beaker was irradiated with sunlight with a power of 40 W, at a distance of 30 cm from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst according to the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method is the same as in Example 1 above). The results are: bisphenol A degradation rate = 83.23%, rhodamine B degradation rate = 79.42%.

[0059] Example 5

[0060] A method for preparing a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0061] (1) Diatomite with a fineness of 200 mesh was mixed with 2 mol / L nitric acid at a ratio of 1 g: 12 mL and stirred uniformly, then immersed for 40 min. After completion, manganese oxide and iron oxide were added at a molar ratio of Mn:Fe = 1:2 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then sodium hydroxide solution was added to adjust the pH of the system to 10 to obtain a modified diatomite mixture.

[0062] (2) Tetraethyl titanate was added to the modified diatomite mixture at a mass fraction of 20% of diatomite, and after stirring uniformly, hydrothermal reaction was carried out in a reaction kettle (temperature 190°C, time 15 hours). After completion, the solid product was filtered out to obtain a precursor.

[0063] (3) The precursor, zinc acetate, and water were mixed at a ratio of 1 g: 0.35 g: 10 mL and stirred uniformly, then dried at 80°C until the mass of the solid product no longer changed. The solid product was then transferred to a box furnace (with nitrogen as the protective atmosphere), heated to 450°C at a heating rate of 5°C / min, and calcined for 1.5 h. After completion, it was cooled to room temperature, washed with clean water, and dried to obtain the catalyst, as shown in Figure 7 .

[0064] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (both pollutants have an initial concentration of 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 0.7 g / L, and stirred magnetically for 1 min, then 0.02 g / L of sodium persulfate was added and stirred uniformly, while the beaker was irradiated with sunlight with a power of 40 W, 30 cm away from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst according to the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method is the same as in Example 1 above). The results are: bisphenol A degradation rate = 87.01%, rhodamine B degradation rate = 83.51%.

[0065] Example 6

[0066] A method for preparing a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0067] (1) Diatomite with a fineness of 200 mesh was mixed with 5 mol / L nitric acid at a ratio of 1 g:7 mL, then stirred uniformly, and then immersed for 60 min. After completion, manganese oxide and iron oxide were added according to a molar ratio of Mn:Fe = 1:2.05 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then ammonia water was added to adjust the pH of the system to 11 to obtain a modified diatomite mixture.

[0068] (2) The modified diatomite mixture was subjected to a hydrothermal reaction in a reaction kettle (temperature 230°C, time 11 hours). After completion, the solid product was filtered out to obtain a precursor.

[0069] (3) The precursor, zinc sulfate, and water were mixed at a ratio of 1 g:0.2 g:5 mL, then stirred uniformly, and then dried at 110°C until the mass of the solid product no longer changed. The solid product was then transferred to a box furnace (with nitrogen as the protective atmosphere), heated to 450°C at a heating rate of 5°C / min, and calcined for 1.5 h. After completion, it was cooled to room temperature, and the obtained calcined product was subjected to reduction treatment in a hydrogen atmosphere (temperature 500°C, time 2 hours). After completion, it was cooled to room temperature, washed with clean water, and dried to obtain the catalyst, as shown in Figure 8 .

[0070] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (both pollutants have an initial concentration of 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 1.3 g / L, and stirred magnetically for 1 min, then 0.04 g / L of sodium persulfate was added and stirred uniformly, while the beaker was irradiated with sunlight with a power of 40 W, 30 cm away from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst according to the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method is the same as in Example 1 above). The results are: bisphenol A degradation rate = 70.45%, rhodamine B degradation rate = 73.13%.

[0071] Example 7

[0072] A method for preparing a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0073] (1) Diatomite with a fineness of 200 mesh was mixed with 2 mol / L nitric acid at a ratio of 1 g: 12 mL, then stirred uniformly, and then immersed for 40 min. After completion, sodium hydroxide solution was added to adjust the pH of the system to 10 to obtain a modified diatomite mixture.

[0074] (2) Tetraethyl titanate was added to the modified diatomite mixture at a ratio of 20% of the mass of diatomite, and after stirring uniformly, a hydrothermal reaction was carried out in a reaction kettle (temperature 190°C, time 15 hours). After completion, the solid product was filtered out to obtain a precursor.

[0075] (3) The precursor, zinc acetate, and water were mixed at a ratio of 1 g: 0.35 g: 10 mL, then stirred uniformly, and then dried at 80°C until the mass of the solid product no longer changed. Then the solid product was transferred to a box furnace (the protective atmosphere was nitrogen), and heated at a rate of 5°C / min to 450°C and calcined for 1.5 h. After completion, it was cooled to room temperature, and then the obtained calcined product was subjected to reduction treatment in a hydrogen atmosphere (temperature 600°C, time 1 hour). After completion, it was cooled to room temperature, washed with clean water, and then dried to obtain the catalyst.

[0076] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (the initial concentration of the two pollutants was 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 0.7 g / L, and stirred for 1 min with a magnetic field, then 0.02 g / L of sodium persulfate was added and stirred evenly, and the beaker was irradiated with sunlight with a power of 40 W, at a distance of 30 cm from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst by the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method was the same as in Example 1 above). The results were: bisphenol A degradation rate = 75.12%, rhodamine B degradation rate = 72.53%.

[0077] Example 8

[0078] A method for preparing a manganese ferrite-diatomite sewage treatment catalyst, comprising the following steps:

[0079] (1) Diatomite with a fineness of 200 mesh was mixed with 4 mol / L nitric acid at a ratio of 1 g:10 mL, and then stirred evenly, and then immersed for 50 min. After completion, manganese oxide and iron oxide were added at a molar ratio of Mn:Fe = 1:2 to convert the residual nitric acid into manganese nitrate and iron nitrate. Then ammonia water was added to adjust the pH of the system to 12 to obtain a modified diatomite mixture.

[0080] (2) The modified diatomite mixture was added to a reaction kettle for hydrothermal reaction (temperature 200°C, time 12 hours). After completion, the solid product was filtered out, washed with clean water and dried to obtain the catalyst.

[0081] Degradation performance test: 100 mL of a solution containing bisphenol A and rhodamine B (the initial concentration of the two pollutants was 10 mg / L) was placed in a beaker, then the catalyst prepared in this example was added to the solution at a ratio of 1.0 g / L, and stirred for 1 min with a magnetic field, then 0.03 g / L of sodium persulfate was added and stirred evenly, and the beaker was irradiated with sunlight with a power of 40 W, at a distance of 30 cm from the liquid surface in the beaker. At time t = 20 min, the catalyst was separated by an external magnetic field to obtain the first recovered catalyst. After obtaining the tenth recovered catalyst by the above method, the concentrations of bisphenol A and rhodamine B in the solution were tested, and the degradation rates were calculated (the calculation method was the same as in Example 1 above). The results were: bisphenol A degradation rate = 62.59%, rhodamine B degradation rate = 66.65%.

[0082] The above merely describes the preferred embodiments of the present application and is not used to limit the present application, and although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or equivalently replace some technical features thereof. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A process for the preparation of a manganese ferrite- kieselguhr sewage treatment catalyst, characterized in that The method comprises the following steps: (1) dipping diatomite in nitric acid, adding manganese oxide and iron oxide according to the molar ratio of Mn:Fe=1:2~2.05 to convert residual nitric acid into manganese nitrate and iron nitrate, then adding alkali to adjust the system to alkaline to obtain a modified diatomite mixture; (2) adding tetraethyl titanate to the modified diatomite mixture and mixing, then performing hydrothermal reaction, separating the solid product to obtain a precursor; (3) mixing the precursor, zinc acetate and water, drying to remove water, and performing calcination in a protective atmosphere; after cooling to room temperature, performing heating reduction treatment in a hydrogen atmosphere, washing and drying the product to obtain the catalyst.

2. The method of claim 1, wherein the manganese ferrite-diatomic earth sewage treatment catalyst is prepared by the steps of: In step (1), the ratio of diatomite to nitric acid is 1g:7~12mL.

3. The method of claim 2, wherein the manganese ferrite-diatomic earth sewage treatment catalyst is prepared by the steps of: In step (1), the concentration of nitric acid is 2~5mol / L.

4. The method of claim 1, wherein the manganese ferrite-diatomic earth sewage treatment catalyst is prepared by the steps of: In step (1), the dipping time is 40~60min.

5. The method of claim 1, wherein the manganese ferrite- diatomite sewage treatment catalyst is prepared by the steps of: In step (1), the pH of the system is adjusted to 10~12 using the alkali.

6. The method of claim 1, wherein the manganese ferrite- diatomite sewage treatment catalyst is prepared by the steps of: In step (1), the alkali includes at least one of sodium hydroxide solution, potassium hydroxide solution and ammonia.

7. The method of claim 1, wherein the manganese ferrite- diatomite sewage treatment catalyst is prepared by the steps of: In step (2), the tetraethyl titanate is 14~20% of the mass of diatomite.

8. The method of making a manganese ferrite- kieselguhr sewage treatment catalyst according to claim 1, characterized in that, In step (2), the temperature of the hydrothermal reaction is 190~230℃, and the reaction time is 11~15 hours.

9. The method of making a manganese ferrite- kieselguhr sewage treatment catalyst according to claim 1, characterized in that, In step (3), the precursor, Zn 2+ The ratio of the source, water is 1 g: 0.2 ~ 0.35 g: 5 ~ 10 mL.

10. The method of claim 1, wherein the manganese ferrite- diatomite sewage treatment catalyst is prepared by the steps of: In step (3), the drying temperature is 80~110℃, and the temperature is maintained until the mass of the solid product no longer changes.

11. The method of making a manganese ferrite- kieselguhr sewage treatment catalyst according to claim 1, characterized in that, In step (3), the calcination temperature is 400~450℃, and the time is 1.5~2 hours.

12. The method of making a manganese ferrite- kieselguhr sewage treatment catalyst according to claim 1, characterized in that, In step (3), the protective atmosphere includes at least one of nitrogen and argon.

13. The method of making a manganese ferrite- kieselguhr sewage treatment catalyst according to any one of claims 1 to 12, characterized in that, In step (3), the heating temperature of the reduction treatment is 500~600℃, and the time is 1~2 hours.

14. The application of the manganese ferrite-diatomite wastewater treatment catalyst according to any one of claims 1-13 in wastewater purification treatment.

15. Use according to claim 14, characterized in that, The persulfate is added to the wastewater during the purification treatment.

16. The use according to claim 15, characterized in that, The amount of persulfate added to the wastewater is 0.02~0.04g / L.

17. The use according to claim 15, characterized in that, The persulfate includes at least one of sodium persulfate and potassium persulfate.

18. The use according to any one of claims 14 to 17, characterized in that, The amount of catalyst added to the wastewater is 0.7~1.3g / L.

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