Catalyst for degrading wastewater and preparation method thereof
By loading manganese oxide and cerium oxide onto an organically modified natural zeolite support, and supplementing it with cobalt oxide, a highly efficient and stable catalyst was prepared, which solved the problems of insufficient activity and high cost of existing catalysts, and achieved efficient degradation of complex industrial wastewater.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN TPRI WATER & ENVIRONMENTAL PROTECTION
- Filing Date
- 2025-11-28
- Publication Date
- 2026-04-17
AI Technical Summary
Existing catalysts have limited catalytic activity, their active components are easily soluble, and they are costly, making it difficult to effectively treat complex industrial wastewater, especially the recalcitrant organic matter in the circulating water discharge from power plants.
Using manganese oxide and cerium oxide as active ingredients and cobalt oxide as auxiliary ingredients, the catalyst is prepared by loading it onto an organically modified natural zeolite support and mixing and calcining it. This process forms multiple redox cycles, enriches the catalytic active sites, and improves the ozone catalytic efficiency.
It achieves efficient and stable degradation of organic matter in the circulating wastewater of power plants, with a COD degradation rate of over 80%. The catalyst is adaptable to complex water quality and is inexpensive.
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Abstract
Description
Technical Field
[0001] This application belongs to the field of wastewater treatment technology, specifically relating to a catalyst for degrading wastewater and its preparation method. Background Technology
[0002] Due to water scarcity, many power plants in northern China have received environmental impact assessment approvals for using urban reclaimed water as their water source. The wastewater discharged from these power plants, primarily high-concentration circulating water, accounts for over 70% of the total wastewater discharge. It contains large amounts of aromatic hydrocarbons, humic acid, fulvic acid, pharmaceutical and personal care product (PPCP) compounds, and scale inhibitors and corrosion dispersants in the cooling tower circulating water. This wastewater is a type of industrial wastewater containing recalcitrant organic compounds, posing a significant threat to the aquatic environment and human health. Furthermore, during desalination and reuse, the organic matter severely fouls the reverse osmosis membrane.
[0003] Currently, most domestic wastewater treatment plants use a process of clarification / softening / filtration followed by reverse osmosis to treat circulating water. However, this pretreatment is ineffective at removing recalcitrant organic matter, leading to severe organic contamination in the reverse osmosis feed water and significant fouling during actual operation. Therefore, it is necessary to enhance organic matter removal in the pretreatment stage, employing methods such as chemical oxidation, activated carbon adsorption, electrochemical adsorption, Fenton oxidation, and ozone catalytic oxidation.
[0004] Ozone catalytic oxidation technology has great potential in power plant wastewater treatment, as it is a highly efficient, clean, low-cost, broad-spectrum technology that combines sterilization, deodorization, and decolorization. The catalyst used in ozone catalytic oxidation technology has been extensively studied and is one of the key factors in its effective application. Existing technologies disclose an ozone oxidation catalyst supported on transition metals and rare earth metals, but it suffers from problems such as low active component content, difficulty in raw material mining, and high preparation costs. Existing technologies also disclose a method for preparing a Co3O4 composite catalyst for ozone catalytic oxidation. This technology discloses that Co3O4 acts as a catalyst to catalyze ozone, effectively removing chlorobenzoic acid from wastewater in a short time. However, due to the single active component of the catalyst, the treatment effect and ozone utilization rate will significantly decrease when the types of pollutants in the wastewater are complex. In addition, current catalyst supports mostly use carbon-based (AC) and aluminum-based (Al2O3) materials. Carbon-based materials have low structural strength, and long-term use can lead to wear, severe loss of active components, and blockage of packed towers. Furthermore, carbon-based materials pose a risk of frictional explosion in confined spaces. Aluminum-based materials only provide surface adsorption sites in catalytic reactions, resulting in low activity and high cost, which limits their widespread use. Therefore, it is particularly important to provide a catalyst that is simple to prepare, highly efficient, stable, and low-cost. Summary of the Invention
[0005] This application provides a catalyst for degrading wastewater and its preparation method, aiming to solve the problems of limited catalytic activity, easy dissolution of active components, and high cost of traditional catalysts. The present invention provides a catalyst and its preparation method with many advantages such as high activity, simple preparation process, environmental protection, high efficiency and stability and low cost.
[0006] The first aspect of this application provides a catalyst for degrading wastewater, comprising a support, an active component and an auxiliary component supported on the support; The active ingredients include manganese oxide and cerium oxide; The auxiliary components include cobalt oxide.
[0007] According to some embodiments of the catalyst for wastewater degradation described in this application, the carrier comprises organically modified natural zeolite.
[0008] According to some embodiments of the catalyst for wastewater degradation described in this application, the molar ratio of manganese oxide and cerium oxide in the active ingredient is (2-6):1.
[0009] According to some embodiments of the catalyst for degrading wastewater described in this application, the mass content of the active ingredient in the catalyst for degrading wastewater is 2%-5%.
[0010] According to some embodiments of the catalyst for degrading wastewater described in this application, the molar ratio of the auxiliary component to the active component in the catalyst for degrading wastewater is 1:(2-5).
[0011] A second aspect of this application provides a method for preparing the catalyst for degrading wastewater as described in the first aspect of this application, comprising the following steps: (1) Mix the support, activator, auxiliary agent, stabilizer, inducer and first solvent to form a mixture, and react to obtain the catalyst precursor; (2) The catalyst precursor is calcined to obtain the catalyst used for degrading wastewater.
[0012] According to some embodiments of the method for preparing a catalyst for degrading wastewater as described in this application, in step (1), the activator includes manganese salt and cerium salt, preferably manganese nitrate and cerium nitrate.
[0013] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the auxiliary agent includes cobalt salt, preferably cobalt nitrate.
[0014] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, the stabilizer includes polyethylene glycol.
[0015] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the inducing agent includes ammonium nitrate.
[0016] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, the first solvent includes water.
[0017] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, in step (1), the molar ratio of manganese salt and cerium salt in the mixture is (2-6):1.
[0018] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, the molar ratio of the auxiliary agent and the activator in the mixture is 1:(2-5).
[0019] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the molar ratio of the activator and the stabilizer in the mixture is (4-6):1.
[0020] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the molar ratio of the activator and the inducer in the mixture is (4-6):1.
[0021] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the mass concentration of the carrier in the mixture is 50-200 g / L.
[0022] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, in step (1), the reaction temperature is 30-40℃, the reaction time is 12-36h, and the stirring speed is 20-30r / min.
[0023] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, in step (2), the calcination temperature is 400-550℃ and the calcination time is 2-5h.
[0024] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the calcination heating rate is 105-120℃ / h.
[0025] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, the method further includes the step of organically modifying the support: The specific operation of organic modification is as follows: mix the carrier and the organic modifier solution to obtain the organic modified carrier.
[0026] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the organic modifier contained in the organic modifier solution is dodecyl dimethyl benzyl ammonium chloride.
[0027] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the concentration of the organic modifier solution is 0.05-0.1 mol / L.
[0028] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the mass ratio of the carrier to the organic modifier is (3-4):1.
[0029] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the mixing temperature is 30-40℃, the mixing time is 6-8h, and the mixing stirring speed is 20-30r / min.
[0030] According to some embodiments of the method for preparing the catalyst for degrading wastewater described in this application, the method further includes the step of cleaning and pretreating the support, and then performing organic modification on the support after pretreating it. The specific pretreatment operation is as follows: the carrier is washed and calcined in sequence.
[0031] According to some embodiments of the preparation method of the catalyst for degrading wastewater described in this application, the calcination temperature during the pretreatment process is 300-400℃ and the time is 2-5h.
[0032] The beneficial effects of this application include: the catalyst for degrading wastewater described in this application contains cobalt oxide, a co-doped active component containing manganese and cerium elements, which provides a synergistic additive. The resulting catalyst has abundant active sites and high catalytic performance, which is beneficial to improving ozone catalytic efficiency, accelerating the degradation of organic matter in wastewater, and achieving efficient degradation of COD in power plant circulating wastewater. Detailed Implementation The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.
[0033] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0034] This application provides a catalyst for degrading wastewater, comprising a support, an active component and auxiliary components supported on the support; The active ingredients include manganese oxide and cerium oxide; The auxiliary components include cobalt oxide.
[0035] The catalyst for wastewater degradation described in this application contains cobalt oxide, a co-doped active component containing manganese and cerium, and a synergistic additive. Because manganese and cerium have multiple oxidation states, they can form Mn... 2+ Mn 3+ Ce 3+ Ce 4+ Multiple redox cycles facilitate electron transfer, and electron transfer between lattice oxygens allows Mn and Ce to have a synergistic effect, catalyzing the production of •OH and •O2 from O3. - The presence of various forms of oxygen within cobalt oxides enriches the active sites of the catalyst, enhancing its catalytic performance. This improves ozone catalytic efficiency, accelerates the degradation of organic matter in wastewater, and achieves a COD degradation rate of over 80% in power plant circulating wastewater. The catalyst described in this application is highly efficient, stable, and adaptable to complex water qualities.
[0036] In some embodiments of this application, the carrier includes organically modified natural zeolite; organic modification of zeolite can improve its adsorption and ion exchange capacity, increase its mechanical strength, and enhance its surface activity.
[0037] In some embodiments of this application, the molar ratio of manganese oxide to cerium oxide in the active ingredients is (2-6):1; for example, 2:1, 3:1, 4:1, 6:1, etc. Manganese is a transition metal with a band structure and abundant d electrons, enabling it to participate in various redox reactions. Cerium is a rare earth element; cerium doping alters its own electronic structure. The combination of the two metals forms a richer band structure, which helps the catalyst provide suitable energy levels in the catalytic reaction. Simultaneously, it regulates the surface band structure of the catalyst, enhancing its adsorption and activation performance. A ratio of too low or too high manganese oxide to cerium oxide will affect its catalytic activity. A low manganese-cerium ratio is insufficient to form a richer band structure, making it difficult to exert a synergistic effect. A high manganese-cerium ratio causes cerium to occupy the active sites on the catalyst surface, resulting in insufficient loading of the more catalytically active manganese oxide and a decrease in overall catalytic activity.
[0038] In some embodiments of this application, the mass content of the active ingredient in the catalyst used for degrading wastewater is 2%-5%; for example, 2%, 3%, 4%, 5%, etc.
[0039] In some embodiments of this application, the molar ratio of the auxiliary component to the active component in the catalyst for degrading wastewater is 1:(2-5), for example, 1:2, 1:3, 1:5, etc. Too much auxiliary agent leads to high catalyst cost, while too much or too little will reduce catalyst performance. At low content, cobalt oxide is insufficient to form suitable Co. 2+ and Co 3+ Redox cycles are insufficient to provide suitable active sites; when the content is high, the active sites on the catalyst surface are covered and the pores may be blocked, resulting in a decrease in catalytic performance. At the same time, it can also lead to the dissolution of metal ions, which deteriorates the quality of the effluent.
[0040] This application also provides a method for preparing the catalyst for degrading wastewater as described in the first aspect of this application, comprising the following steps: (1) Mix the support, activator, auxiliary agent, stabilizer, inducer and solvent to form a mixture, and react to obtain the catalyst precursor; (2) The catalyst precursor is calcined to obtain the catalyst used for degrading wastewater.
[0041] The addition of stabilizers and inducers during the catalyst preparation process described in this application allows the stabilizers and inducers to improve the particle size distribution of the catalyst, control the catalyst morphology, and enhance the catalyst stability through intramolecular interactions of hydrogen bonds and van der Waals forces. This provides the catalyst with more active sites and coordination bonds, thereby increasing the catalytic activity of the catalyst.
[0042] In some embodiments of this application, in step (1), the activator includes manganese salt and cerium salt, preferably manganese nitrate and cerium nitrate. Manganese and cerium have various oxidation forms and can form Mn 2+ Mn 3+ Ce 3+ Ce 4+ Multiple redox cycles facilitate electron transfer, and electron transfer between lattice oxygens allows Mn and Ce to have a synergistic effect, catalyzing the production of •OH and •O2 from O3. - It helps to improve the stability and selectivity of the catalyst.
[0043] In some embodiments of this application, the auxiliary agent includes cobalt salt, preferably cobalt nitrate; the addition of the auxiliary agent can enrich the active sites of the catalyst, and generate a synergistic effect with the active component during the catalytic process, thereby improving the catalytic performance of the catalyst.
[0044] In some embodiments of this application, the stabilizer includes polyethylene glycol (PEG). The addition of PEG can improve the catalyst particle size distribution, enhance the catalyst's stability and selectivity, and control the catalyst morphology and size. PEG, as an organic carbon source, provides carbon to the catalyst, increasing its active sites.
[0045] In some embodiments of this application, the inducing agent includes ammonium nitrate; the addition of ammonium nitrate can form coordination bonds with the active sites on the catalyst, and affect the structure and activity of the catalyst through interactions such as hydrogen bonds and van der Waals forces, forming a catalyst with a uniform pore structure.
[0046] In some embodiments of this application, the first solvent includes water.
[0047] In some embodiments of this application, in step (1), the molar ratio of manganese salt and cerium salt in the mixture is (2-6):1, for example 2:1, 3:1, 4:1, 6:1, etc.
[0048] In some embodiments of this application, the molar ratio of the auxiliary agent to the active agent in the mixture is 1:(2-5); for example, 1:2, 1:3, 1:4, 1:5, etc.
[0049] In some embodiments of this application, the molar ratio of the activator and the stabilizer in the mixture is (4-6):1, for example 4:1, 5:1, 6:1, etc.
[0050] In some embodiments of this application, the molar ratio of the activator and the inducer in the mixture is (4-6):1; for example, 4:1, 5:1, 6:1, etc.
[0051] In some embodiments of this application, the mass concentration of the carrier in the mixture is 50-200 g / L; for example, 50 g / L, 80 g / L, 120 g / L, 150 g / L, 170 g / L, 200 g / L, etc.
[0052] In some embodiments of this application, in step (1), the reaction temperature is 30-40°C, the reaction time is 12-36h, and the stirring speed is 20-30r / min.
[0053] In some embodiments of this application, in step (2), the calcination temperature is 400-550℃, such as 400℃, 430℃, 450℃, 480℃, 520℃, 550℃, etc., and the calcination time is 2-5h. If the calcination temperature is too low or the time is too short, the active components and additives on the modified natural zeolite surface cannot completely form metal oxides with better crystal form and higher activity, resulting in poor catalytic performance. If the temperature is too high or the calcination time is too long, sintering or partial sintering will occur on the catalyst surface, and the crystals will melt and the channels will collapse, reducing the specific surface area and pore volume, thereby causing the loss or reduction of active sites on the catalyst surface, resulting in a decrease in catalyst activity.
[0054] In some embodiments of this application, the heating rate of the calcination is 105-120℃ / h, such as 105℃ / h, 108℃ / h, 110℃ / h, 112℃ / h, 115℃ / h, 120℃ / h, etc.
[0055] In some embodiments of this application, the step of organically modifying the carrier is also included: The specific operation of organic modification is as follows: the carrier and the organic modifier solution are mixed to obtain the organically modified carrier. Modifying the carrier with an organic modifier can remove impurities from the carrier surface and improve the carrier's cleanliness and surface activity.
[0056] In some embodiments of this application, the organic modifier solution contains dodecyl dimethyl benzyl ammonium chloride. Dodecyl dimethyl benzyl ammonium chloride is a cationic surfactant with highly efficient detergency. Modifying natural zeolite with dodecyl dimethyl benzyl ammonium chloride can balance the electronegativity of the zeolite surface and improve its adsorption and catalytic properties.
[0057] In some embodiments of this application, the concentration of the organic modifier solution is 0.05-0.1 mol / L; for example, 0.05 mol / L, 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, etc.
[0058] In some embodiments of this application, the mass ratio of the carrier to the organic modifier is (3-4):1; for example, 3:1, 3.5:1, 3.8:1, 4:1, etc.
[0059] In some embodiments of this application, the mixing temperature is 30-40°C, the mixing time is 6-8 hours, and the mixing stirring speed is 20-30 r / min. After the mixing reaction, the supernatant is removed by centrifugation, and then washed with distilled water. This process is repeated multiple times until chloride ions are no longer detectable. The pretreated natural zeolite after washing is dried in an oven at 110°C for 6 hours to obtain organically modified natural zeolite.
[0060] In some embodiments of this application, the method further includes a step of cleaning and pre-treating the carrier before organic modification. The specific operation of the pre-treatment is to sequentially clean and calcine the carrier.
[0061] Natural zeolite is selected, ground, and sieved to prepare a carrier with a large specific surface area and suitable particle size. Soluble inorganic substances on the surface of the sieved zeolite are removed by ultrasonic cleaning with distilled water. The washed zeolite is then dried in an oven at 110℃ for 3 hours to remove surface moisture. The particle size of natural zeolite is generally 0.5-1.2 mm.
[0062] In some embodiments of this application, the calcination temperature during the pretreatment process is 300-400℃, such as 300℃, 320℃, 350℃, 360℃, 380℃, 400℃, etc., for 2-5 hours. The dried zeolite particles are placed in a muffle furnace at 300-400℃ for low-temperature calcination for 2-5 hours to remove insoluble organic matter, while simultaneously increasing the mechanical strength and ion exchange capacity of the carrier, resulting in clean natural zeolite.
[0063] The technical solution of this application will be further described below with reference to specific embodiments.
[0064] Example 1 A method for preparing a catalyst for degrading wastewater includes the following steps: (1) Select natural zeolite, grind and sieve to obtain natural zeolite particles with a particle size of 0.5-1.2 mm, wash with ultrasonic distilled water, and dry the washed natural zeolite in an oven at 110℃ for 3 hours, and then calcine it in a muffle furnace at 400℃ for 2 hours to obtain pretreated natural zeolite. (2) Pretreated natural zeolite and dodecyl dimethyl benzyl ammonium chloride in a mass ratio of 3:1 were mixed in water (the concentration of dodecyl dimethyl benzyl ammonium chloride in the mixture was 0.06 mol / L). The mixing temperature was set at 35℃ and stirred at 30 r / min for 6 h. After the mixing was completed, the mixture was placed in a centrifuge to remove the supernatant and washed with distilled water until no chloride ions could be detected. The washed natural zeolite was placed in a 110℃ oven and dried for 6 h to obtain organic modified natural zeolite. (3) 0.04 mol manganese nitrate, 0.01 mol cerium nitrate, 0.017 mol cobalt nitrate, 0.4 kg organic modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate and water were mixed and reacted at 35°C for 16 h. After the reaction was completed, the mixture was filtered. The filtered mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate and cobalt nitrate) were placed in an oven at 110°C and dried for 6 h. Then, they were placed in a muffle furnace and heated to 550°C at a rate of 120°C / h. The mixture was kept at 550°C and calcined for 3 h to oxidize the manganese nitrate, cerium nitrate and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide and cobalt oxide, respectively, to obtain the catalyst used for degrading wastewater.
[0065] Example 2 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 2 and Example 1 is that the ratio of manganese nitrate and cerium nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 2 is different from that in Example 1.
[0066] The specific operating steps include: 0.02 mol manganese nitrate, 0.01 mol cerium nitrate, 0.017 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were placed in an oven at 110°C and dried for 6 h. Then, the mixture was placed in a muffle furnace and heated to 550°C at a controlled heating rate of 120°C / h. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, to obtain the catalyst for wastewater degradation. The remaining operation steps were the same as in Example 1.
[0067] Example 3 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 3 and Example 1 is that the ratio of manganese nitrate and cerium nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 3 is different from that in Example 1.
[0068] The specific operating steps include: 0.03 mol manganese nitrate, 0.01 mol cerium nitrate, 0.017 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were placed in an oven at 110°C and dried for 6 h. Then, the mixture was placed in a muffle furnace and heated to 550°C at a controlled heating rate of 120°C / h. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, to obtain the catalyst for wastewater degradation. The remaining operation steps were the same as in Example 1.
[0069] Example 4 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 4 and Example 1 is that the ratio of manganese nitrate and cerium nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 4 is different from that in Example 1.
[0070] The specific operating steps include: 0.06 mol manganese nitrate, 0.01 mol cerium nitrate, 0.017 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were placed in an oven at 110°C and dried for 6 h. Then, the mixture was placed in a muffle furnace and heated to 550°C at a controlled heating rate of 120°C / h. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, to obtain the catalyst for wastewater degradation. The remaining operation steps were the same as in Example 1.
[0071] Example 5 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 5 and Example 1 is that the amount of cobalt nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 5 is different from that in Example 1.
[0072] The specific operating steps include: 0.04 mol manganese nitrate, 0.01 mol cerium nitrate, 0.01 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were dried in an oven at 110°C for 6 h, and then placed in a muffle furnace. The temperature was controlled at a rate of 120°C / h and heated to 550°C. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, thus obtaining the catalyst for wastewater degradation.
[0073] Example 6 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 6 and Example 1 is that the amount of cobalt nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 6 is different from that in Example 1.
[0074] The specific operating steps include: 0.04 mol manganese nitrate, 0.01 mol cerium nitrate, 0.0125 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were dried in an oven at 110°C for 6 h, and then placed in a muffle furnace. The temperature was controlled at a rate of 120°C / h and heated to 550°C. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, thus obtaining the catalyst for wastewater degradation.
[0075] Example 7 The only difference between the preparation method of the catalyst for degrading wastewater described in Example 7 and Example 1 is that the amount of cobalt nitrate used in the preparation process of the catalyst for degrading wastewater described in Example 7 is different from that in Example 1.
[0076] The specific operating steps include: 0.04 mol manganese nitrate, 0.01 mol cerium nitrate, 0.025 mol cobalt nitrate, 0.4 kg organically modified natural zeolite, 0.01 mol polyethylene glycol, 0.01 mol ammonium nitrate, and water were mixed and reacted at 35°C for 16 h. After the reaction was complete, the mixture was filtered. The resulting mixed particles (natural zeolite loaded with manganese nitrate, cerium nitrate, and cobalt nitrate) were placed in an oven at 110°C and dried for 6 h. Then, the mixture was placed in a muffle furnace and heated to 550°C at a controlled heating rate of 120°C / h. The mixture was then calcined for 3 h to oxidize the manganese nitrate, cerium nitrate, and cobalt nitrate loaded on the natural zeolite into manganese oxide, cerium oxide, and cobalt oxide, respectively, thus obtaining the catalyst for wastewater degradation.
[0077] Comparative Example 1 The only difference between the preparation method of the catalyst for degrading wastewater described in Comparative Example 1 and Example 1 is that ferric nitrate is used instead of cerium nitrate in the preparation process of the catalyst for degrading wastewater described in Comparative Example 1.
[0078] Comparative Example 2 The only difference between the preparation method of the catalyst for degrading wastewater described in Comparative Example 2 and Example 1 is that nickel nitrate is used instead of cobalt nitrate in the preparation process of the catalyst for degrading wastewater described in Comparative Example 2.
[0079] Comparative Example 3 The only difference between the preparation method of the catalyst for degrading wastewater described in Comparative Example 3 and Example 1 is that manganese nitrate was not used in the preparation process of the catalyst for degrading wastewater described in Comparative Example 3.
[0080] Catalytic performance study of the catalysts for wastewater degradation described in Examples 1-7 and Comparative Examples 1-3 of this application. Test method: The catalysts for degrading wastewater described in Examples 1-7 and Comparative Examples 1-3 of this application were placed in actual power plant circulating water discharge samples. The volume of each sample was 1L, the dosage of each catalyst was 50g, the ozone dosage was 120mg / L, and the soaking time was 60min. Then, the COD concentration in the supernatant was determined by the potassium dichromate method. The results are shown in Table 1.
[0081] Stability Test: The catalysts described in Examples 1-7 and Comparative Examples 1-3 of this application were respectively immersed in actual circulating water wastewater samples obtained from power plants (these samples were concentrated wastewater from cooling towers using urban reclaimed water as a source, with high organic content, and also contained scale inhibitors, corrosion inhibitors, dispersants, etc., with a COD value of approximately 100 mg / L). The immersion amount of each catalyst was 50 g / L. The samples were placed on a shaker and shaken, and then the concentration of active metal ions in the water was measured. The results are shown in Table 1.
[0082] Table 1
[0083] As can be seen from Table 1, the catalyst prepared in the embodiments of this application for degrading wastewater has the highest COD removal rate in the circulating water discharge of power plants, and the active components Mn and Ce are stable.
[0084] Comparing Examples 1-4, it can be seen that when the molar ratio of manganese nitrate to cerium nitrate in the activator is (3-4):1, the prepared catalyst for degrading wastewater has the highest COD removal rate in the circulating water of the power plant, and the active components Mn and Ce are stable and do not dissolve.
[0085] Comparing Examples 1 and 5-7, it can be seen that when the molar ratio of the auxiliary agent to the activator is (1-1.7):5, the prepared catalyst for degrading wastewater has the highest COD removal rate in the circulating water of the power plant, and the active components Mn and Ce are stable and do not dissolve.
[0086] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.
Claims
1. A catalyst for degrading wastewater, characterized by, Includes the carrier, the active ingredient and auxiliary ingredients loaded on the carrier; The active ingredients include manganese oxide and cerium oxide; The auxiliary components include cobalt oxide.
2. The catalyst for degrading wastewater according to claim 1, wherein The carrier includes organically modified natural zeolite; And / or, the molar ratio of manganese oxide to cerium oxide in the active ingredient is (2-6):1; And / or, the active ingredient in the catalyst for degrading wastewater has a mass content of 2%-5%; And / or, the molar ratio of the auxiliary component to the active component in the catalyst for degrading wastewater is 1:(2-5).
3. The process for the preparation of the catalyst for the degradation of waste water according to any one of claims 1-2, characterized by, Includes the following steps: (1) Mix the support, activator, auxiliary agent, stabilizer, inducer and first solvent to form a mixture, and react to obtain the catalyst precursor; (2) The catalyst precursor is calcined to obtain the catalyst used for degrading wastewater.
4. The method for preparing the catalyst for degrading wastewater according to claim 3, characterized in that, In step (1), the activator includes manganese salt and cerium salt, preferably manganese nitrate and cerium nitrate; And / or, the auxiliary agent includes a cobalt salt, preferably cobalt nitrate; And / or, the stabilizer includes polyethylene glycol; And / or, the inducing agent includes ammonium nitrate; And / or, the first solvent includes water.
5. The method for preparing the catalyst for degrading wastewater according to claim 4, characterized in that, In step (1), the molar ratio of manganese salt to cerium salt in the mixture is (2-6):1; And / or, the molar ratio of the auxiliary agent to the active agent in the mixture is 1:(2-5); And / or, the molar ratio of the surfactant to the stabilizer in the mixture is (4-6):1; And / or, the molar ratio of the surfactant to the inducer in the mixture is (4-6):1; And / or, the mass concentration of the carrier in the mixture is 50-200 g / L; And / or, in step (1), the temperature of the reaction is 30-40°C and the reaction time is 12-36h.
6. The method for preparing the catalyst for degrading wastewater according to claim 3, characterized in that, In step (2), the calcination temperature is 400-550℃, and the calcination time is 2-5h; And / or, the calcination heating rate is 105-120℃ / h.
7. The method for preparing the catalyst for degrading wastewater according to claim 3, characterized in that, It also includes the step of organically modifying the carrier: The specific operation of organic modification is as follows: mix the carrier and the organic modifier solution to obtain the organic modified carrier.
8. The method for preparing the catalyst for degrading wastewater according to claim 7, characterized in that, The organic modifier solution contains dodecyl dimethyl benzyl ammonium chloride; And / or, the concentration of the organic modifier solution is 0.05-0.1 mol / L; And / or, the mass ratio of the carrier to the organic modifier is (3-4):1; And / or, the mixing temperature is 30-40℃, the mixing time is 6-8h, and the mixing speed is 20-30r / min.
9. The method for preparing the catalyst for degrading wastewater according to claim 3, characterized in that, It also includes the step of cleaning and pretreating the carrier, and then performing organic modification on the carrier after pretreatment; The specific pretreatment operation is as follows: the carrier is washed and calcined in sequence.
10. The method for preparing the catalyst for degrading wastewater according to claim 9, characterized in that, The calcination process during the pretreatment is carried out at a temperature of 300-400℃ for 2-5 hours.