A method for degrading organic micro-pollutants in water by coupling Fe atomic clusters with Mn-Fe double monatomic catalysts

Abstract

The application provides a method for degrading organic micro-pollutants in water by using Fe atomic cluster coupled Mn-Fe double monatomic catalysis ozone, which comprises the following steps: adding Fe atomic cluster coupled Mn-Fe double monatomic catalyst and water to be treated into an ozone catalytic reaction device to perform ozone aeration. The method effectively utilizes the synergistic effect between the Mn-Fe double monatomic catalysts, and couples the electron optimization effect of the Fe atomic cluster, realizes the design of a high-efficiency and reasonable ozone interface catalytic path, and produces high-activity oxidizing species, which can rapidly degrade refractory organic micro-pollutants in water in a short time, and guarantees the water quality of effluent.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water treatment, and particularly relates to a method for degrading organic micro-pollutants in water by Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone. BACKGROUND

[0002] Organic micro-pollutants are a kind of organic pollutants with low content, toxicity and harm, and difficult to degrade, such as phenols and nitrobenzene organic compounds. At present, they have been frequently detected in natural water bodies, drinking water and sewage, and have posed a great threat to ecological environment safety and human health. According to the investigation, harmful organic pollutants in drinking water are as high as hundreds of kinds. This kind of organic pollutants has a long residence time in water and is difficult to degrade. For conventional drinking water plants, the traditional drinking water treatment process (coagulation / flocculation-sedimentation-filtration-disinfection) is difficult to remove this kind of pollutants, which seriously affects the safety of water supply. For sewage treatment plants, this kind of organic pollutants has very poor biodegradability and is difficult to be effectively removed by traditional biochemical treatment. It is reported that the removal effect of conventional primary treatment on this kind of substances is less than 10%, and the removal of secondary treatment on this kind of substances does not exceed 30%. For industrial wastewater, such as pharmaceutical wastewater, printing and dyeing wastewater, aquaculture wastewater, etc., the removal of this kind of substances is also a big problem. Therefore, it is urgent to develop new and efficient deep water treatment technology for organic micro-pollutants.

[0003] At present, the deep treatment technology mainly includes activated carbon adsorption process, membrane separation process, ozone-based advanced oxidation process, etc. For example, some drinking water plants have adopted ozone-biological activated carbon process as a deep treatment process for drinking water to improve the water quality. Ozone method has been widely used in deep treatment process to treat organic micro-pollutants due to its excellent oxidation capacity and no secondary pollution. Ozone can directly oxidize this kind of organic pollutants through molecular ozone or produce secondary free radicals for indirect oxidation. However, due to the selectivity of oxidation between ozone molecules and pollutants, the oxidation speed of some organic pollutants (such as nitrobenzene, p-chlorobenzoic acid, p-hydroxybenzoic acid, etc.) is relatively slow, which leads to incomplete removal of pollutants, and even produces new toxic intermediates.

[0004] Heterogeneous catalytic ozone oxidation process can decompose ozone into highly oxidized active oxygen species, such as hydroxyl radicals (·OH, 2.70 V), surface atomic oxygen (O*, 2.07 V) and singlet oxygen (1O2, 2.09 V) in a short time. * O ad, 2.43V) and so on. These active oxygen species can achieve the rapid removal of refractory organic micro-pollutants in water, and even mineralization. In this process, the design of the ozone catalyst will be crucial. An efficient ozone catalyst can achieve rapid interfacial catalysis of ozone, converting a large amount of active oxygen species in a short time; an efficient catalytic reaction process will effectively reduce the ozone dosage, shorten the process residence time, reduce the dosage of the catalytic material, increase the water treatment capacity per unit time, and achieve rapid degradation of various refractory organic pollutants. Therefore, it is urgent to construct a synthesis method of an ozone catalyst that can efficiently catalyze ozone to remove refractory organic micro-pollutants, so as to develop a new water treatment method that can efficiently remove organic micro-pollutants in water. SUMMARY

[0005] The present application aims to at least solve one of the above-mentioned technical problems in the prior art. To this end, the present application provides a method for catalyzing ozone to degrade organic micro-pollutants in water by Fe atomic cluster coupled Mn-Fe double monatomic, which effectively utilizes the synergistic effect between Mn-Fe double monatomic and couples the electronic optimization effect of Fe atomic cluster, realizes the design of efficient and reasonable ozone interfacial catalysis path, and produces highly active oxygenated species that can rapidly degrade refractory organic micro-pollutants in water in a short time, ensuring the water quality of the effluent.

[0006] The first aspect of the present application provides a method for catalyzing ozone to degrade organic micro-pollutants in water by Fe atomic cluster coupled Mn-Fe double monatomic, which comprises the step of adding Fe atomic cluster coupled Mn-Fe double monatomic catalyst and water to be treated into an ozone catalytic reaction device for ozone aeration.

[0007] The present application relates to a method for catalyzing ozone to degrade organic micro-pollutants in water by Fe atomic cluster coupled Mn-Fe double monatomic, which has at least the following beneficial effects:

[0008] The method can achieve the rapid removal of various refractory organic micro-pollutants, such as nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol, benzotriazole, etc. In addition, the method has good performance stability and anti-interference during the treatment of refractory organic micro-pollutants, and the removal performance of organic micro-pollutants will not be interfered by water impurities, such as Cl - , SO4 2- , H2PO4 2- , HCO3 - , dissolved organic matter, etc., and has good removal effect in different pH ranges of water quality.

[0009] The treatment strategy of organic micro-pollutants provided by the present application is essentially different from the existing method of removing organic micro-pollutants by ozone catalytic oxidation process. The core lies in that the present application adopts atomic regulation technology to directionally synthesize interface atomic coordination configuration matched with the electronic structure of ozone based on the electronic structure and molecular characteristics of ozone, and realizes the synergistic interface effect of ozone catalysis through the mutual regulation of the electronic structure between Mn and Fe double transition metal atoms. At the same time, the electronic structure of the double single atom site is further optimized by synchronously introducing Fe atom clusters, so as to further optimize the interface adsorption process and catalytic decomposition reaction process of ozone molecules, which is completely different from the existing catalyst synthesis strategy. Therefore, the advanced concept and strategy of the method for efficiently decomposing organic micro-pollutants in water by using Fe atom clusters coupled with Mn-Fe double single atom to catalyze ozone provided by the present application has a very broad application prospect in drinking water treatment, sewage regeneration treatment and industrial wastewater treatment. Specifically, the present application directionally synthesizes Fe atom cluster coupled with Mn-Fe double single atom interface atomic catalytic configuration matched with the electronic structure of ozone based on the electronic structure and molecular characteristics of ozone by using atomic regulation technology. In the nanocatalyst, the content ratio atom% of Mn atom and Fe atom in the Fe atom cluster coupled with Mn-Fe double single atom nanocatalyst is 1-3:3, the specific surface area is 1000-1500m 2 / g, and effective coordination is formed between Mn-N, Mn-Fe, Fe-N and Fe-Fe. The synergistic interface effect of ozone catalysis is realized through the mutual regulation of the electronic structure between Mn and Fe double transition metal atoms; at the same time, the electronic structure of the double single atom site is further optimized by synchronously introducing Fe atom clusters, so as to further optimize the interface adsorption process and catalytic decomposition reaction process of ozone molecules, and significantly improve the catalytic efficiency of ozone.

[0010] The experimental results show that when treating water rich in 5mgC / L of refractory organic micro-pollutants such as nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole, 70%-90% of the above-mentioned refractory organic micro-pollutants can be removed in 120s, and compared with the traditional ozone oxidation process, the removal effect of nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole is increased by 15.72 times, 8.14 times, 6.39 times and 6.91 times respectively. In addition, the method has good performance stability and anti-interference in the process of treating refractory organic pollutants, and the removal performance of the refractory organic micro-pollutant nitrobenzene will not be affected by various anions in water, including 5mM of Cl - 、SO4 2- 、H2PO4 2- 、HCO3 -The performance is not interfered by dissolved organic matter (2 mgC / L or 5 mgC / L) in water. The method exhibits excellent nitrobenzene removal performance under different pH conditions of water (pH range: 3-9).

[0011] The present application is suitable for advanced treatment of urban drinking water plants, and can replace the ozone-biological activated carbon process in the advanced treatment process of drinking water with the Fe atomic cluster coupled Mn-Fe double single-atom catalytic ozone oxidation process, so as to effectively remove refractory organic micropollutants in water. Ozone has the effects of sterilization, disinfection and algae removal, and can ensure water supply safety. The process is simple to operate, and considering that many drinking water plants already have the key structures required for ozone oxidation process, only ozone catalyst needs to be added to realize upgrading and reconstruction of the existing water plant process.

[0012] Further, the present application is suitable for advanced treatment of reclaimed water, and can be used for Fe atomic cluster coupled Mn-Fe double single-atom catalytic ozone oxidation treatment after the effluent process of the secondary sedimentation tank, so as to effectively remove refractory organic micropollutants in water and ensure the quality of effluent. The present application can also be applied to effective treatment of industrial wastewater, such as pharmaceutical wastewater, printing and dyeing wastewater, aquaculture wastewater and other wastewater rich in refractory organic micropollutants. Such wastewater is often difficult to be treated by conventional biochemical treatment. The process can effectively degrade refractory organic micropollutants in water, reduce organic matter in effluent and improve the biodegradability of effluent, so as to realize efficient treatment of industrial wastewater.

[0013] According to some embodiments of the present application, the method further comprises a step of filtering the effluent after ozone aeration to recover solid catalysts in water.

[0014] The effluent after ozone aeration is filtered to recover solid catalysts in water, so as to realize recycling of the catalysts and further reduce the cost.

[0015] According to some embodiments of the present application, the preparation method of the Fe atomic cluster coupled Mn-Fe double single-atom catalyst comprises the steps of preparing a Mn-doped precursor, obtaining a Mn single-atom catalyst and anchoring Fe single atoms and coupling Fe atomic clusters.

[0016] According to some embodiments of the present application, the preparation method of the Fe atomic cluster coupled Mn-Fe double single-atom catalyst comprises the following steps:

[0017] S1: preparing an N ligand solution and a solution containing zinc nitrate hexahydrate and a Mn source in a reaction solvent, mixing the two solutions to obtain a Mn-doped precursor;

[0018] S2: performing acid etching after first heat treatment of the Mn-doped precursor to obtain a Mn single-atom catalyst;

[0019] S3: after the second heat treatment of the Mn monatomic catalyst, dispersing the product in a solvent, adding a Fe source and a N source, centrifuging, washing and drying the sample after reaction, and performing a third heat treatment on the obtained solid product under an inert atmosphere to obtain the Fe atomic cluster coupled Mn-Fe double monatomic catalyst.

[0020] According to some embodiments of the present application, in step S1, the reaction solvent comprises a dimethylformamide solution.

[0021] According to some embodiments of the present application, the N ligand solution comprises a 50-150 mmol / L dimethylimidazole solution.

[0022] According to some embodiments of the present application, the concentration of the zinc nitrate hexahydrate is 25-75 mmol / L.

[0023] According to some embodiments of the present application, the Mn source comprises a 2-20 mM manganese acetate dihydrate solution.

[0024] According to some embodiments of the present application, the temperature of the mixing reaction is 30-120°C.

[0025] According to some embodiments of the present application, the time of the mixing reaction is 8-24 h.

[0026] According to some embodiments of the present application, in step S2, the concentration of the acid solution for acid etching is 0.01-1.0 mol / L.

[0027] According to some embodiments of the present application, the processing time of the acid etching is 1-5 h.

[0028] According to some embodiments of the present application, the processing temperature of the acid etching is 30-100°C.

[0029] According to some embodiments of the present application, the acid etching is used to remove impurities.

[0030] According to some embodiments of the present application, in step S3, the Fe source comprises ferrous chloride.

[0031] According to some embodiments of the present application, the N source comprises cyanamide.

[0032] According to some embodiments of the present application, the atomic ratio of the Fe source and the N source is 1:10-100.

[0033] According to some embodiments of the present application, the temperature of the first heat treatment is 800-1200°C.

[0034] According to some embodiments of the present application, the first heat treatment time is 30 min to 150 min.

[0035] According to some embodiments of the present application, the first heat treatment temperature is 800 to 1200 °C.

[0036] According to some embodiments of the present application, the first heat treatment reduces Mn ions to form Mn monatomic atoms.

[0037] According to some embodiments of the present application, the second heat treatment temperature is 800 to 1200 °C.

[0038] According to some embodiments of the present application, the second heat treatment time is 30 min to 150 min.

[0039] According to some embodiments of the present application, the second heat treatment temperature is 800 to 1200 °C.

[0040] According to some embodiments of the present application, the second heat treatment repairs carbon structure.

[0041] The solid product before the third heat treatment is a Fe atomic cluster coupled Mn-Fe bi-monatomic nanocatalyst precursor.

[0042] According to some embodiments of the present application, the third heat treatment temperature is 800 to 1200 °C.

[0043] According to some embodiments of the present application, the third heat treatment time is 30 min to 150 min.

[0044] According to some embodiments of the present application, the third heat treatment temperature is 800 to 1200 °C.

[0045] According to some embodiments of the present application, the third heat treatment reduces Fe ions to form Fe monatomic atoms. BRIEF DESCRIPTION OF DRAWINGS

[0046] Figure 1 is the degradation curve of p-nitrophenol by separate ozonation and ozone catalytic oxidation of Example 2.

[0047] Figure 2 is the degradation curve of p-hydroxybenzoic acid by separate ozonation and ozone catalytic oxidation of Example 2.

[0048] Figure 3 is the degradation curve of 4-nitrophenol by separate ozonation and ozone catalytic oxidation of Example 2.

[0049] Figure 4 is the degradation curve of benzotriazole by separate ozonation and catalytic ozonation in Example 2.

[0050] Figure 5 is the result of the effect of different anions on catalytic ozonation degradation of nitrobenzene in Example 2.

[0051] Figure 6 is the result of the effect of different concentrations of dissolved organic matter on catalytic ozonation degradation of nitrobenzene in Example 2.

[0052] Figure 7 is the result of the effect of different water quality pH conditions on catalytic ozonation degradation of nitrobenzene in Example 2. DETAILED DESCRIPTION

[0053] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments.

[0054] In the first aspect, some embodiments of the present application provide a method for Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozonation of organic micro-pollutants in water, which comprises the step of adding Fe atomic cluster coupled Mn-Fe double monatomic catalyst and water to be treated into an ozone catalytic reaction device for ozone aeration.

[0055] It can be understood that the method can achieve rapid removal of various refractory organic micro-pollutants, such as nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol, benzotriazole, etc. In addition, the method has good performance stability and anti-interference in the process of treating refractory organic micro-pollutants, and the removal performance of organic micro-pollutants will not be interfered by water quality impurities, such as Cl - , SO4 2- , H2PO4 2- , HCO3 - , dissolved organic matter, etc., and has good removal effect in different water quality pH range.

[0056] The treatment strategy of the organic micro-pollutants provided by the present application is essentially different from the existing method of removing organic micro-pollutants by ozone catalytic oxidation process. The core lies in that the interface atomic coordination configuration matching the electronic structure of ozone is directionally synthesized by using the atomic regulation technology based on the electronic structure and molecular characteristics of ozone, and the synergistic interface effect of ozone catalysis is realized through the mutual regulation of the electronic structure between the Mn and Fe double transition metal atoms. At the same time, the electronic structure of the double single-atom sites is further optimized by synchronously introducing Fe atom clusters, so as to further optimize the interface adsorption process and catalytic decomposition reaction process of ozone molecules, which is completely different from the existing catalyst synthesis strategy. Therefore, the advanced concept and strategy of the method for efficiently decomposing organic micro-pollutants in water by using Fe atom clusters coupled with Mn-Fe double single-atom catalytic ozone have a wide application prospect in drinking water treatment, sewage regeneration treatment and industrial wastewater treatment. Specifically, the Fe atom cluster coupled with Mn-Fe double single-atom interface atomic catalytic configuration matching the electronic structure of ozone is directionally synthesized by using the atomic regulation technology based on the electronic structure and molecular characteristics of ozone. In the nanocatalyst, the content ratio atom% of Mn atom and Fe atom in the Fe atom cluster coupled with Mn-Fe double single-atom nanocatalyst is 1-3:3, the specific surface area is 1000-1500 m 2 / g, and effective coordination is formed between Mn-N, Mn-Fe, Fe-N and Fe-Fe. The synergistic interface effect of ozone catalysis is realized through the mutual regulation of the electronic structure between the Mn and Fe double transition metal atoms; at the same time, the electronic structure of the double single-atom sites is further optimized by synchronously introducing Fe atom clusters, so as to further optimize the interface adsorption process and catalytic decomposition reaction process of ozone molecules, and the catalytic efficiency of ozone is significantly improved.

[0057] The experimental results show that when treating water rich in 5 mg C / L of refractory organic micro-pollutants such as nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole, 70%-90% of the above-mentioned refractory organic micro-pollutants can be removed in 120 s, and compared with the traditional ozone oxidation process, the removal effect of nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole is increased by 15.72 times, 8.14 times, 6.39 times and 6.91 times, respectively. In addition, the method has good performance stability and anti-interference in the process of treating refractory organic pollutants, and the removal performance of the refractory organic micro-pollutant nitrobenzene will not be affected by various anions in water, including 5 mM of Cl - , SO4 2- , H2PO4 2- , HCO3 -; the performance is not interfered by dissolved organic matter (2 mgC / L or 5 mgC / L) in water. In the presence of different pH of water (pH range: 3-9), the method shows excellent removal performance of nitrobenzene.

[0058] The present application is suitable for advanced treatment of urban drinking water plants, and can replace the ozone-biological activated carbon process in the advanced treatment process of drinking water with the Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone oxidation process, so as to effectively remove the refractory organic micropollutants in water. The ozone has the effects of sterilization, disinfection and algae removal, and the like, and thus the water supply safety is ensured. The process is simple to operate, and considering that many drinking water plants already have the key structures required for the ozone oxidation process, the existing water plant process can be upgraded and modified by only adding the ozone catalyst.

[0059] Further, the present application is suitable for advanced treatment of reclaimed water, and the Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone oxidation treatment can be performed after the process of the effluent of the secondary sedimentation tank, so as to effectively remove the refractory organic micropollutants in water and ensure the effluent water quality. The present application can also be applied to effective treatment of industrial wastewater, such as pharmaceutical wastewater, printing and dyeing wastewater, aquaculture wastewater and the like, which are rich in refractory organic micropollutants. Such wastewater is often difficult to be treated by conventional biochemical treatment. The process can effectively degrade the refractory organic micropollutants in water, reduce the organic matter in the effluent and improve the biodegradability, so as to realize efficient treatment of industrial wastewater.

[0060] In combination with the first aspect, in some embodiments of the present application, the method further comprises the step of filtering the effluent after ozone aeration to recover the solid catalyst in water. It can be understood that filtering the effluent after ozone aeration to recover the solid catalyst in water realizes the recycling of the catalyst and further reduces the cost.

[0061] In combination with the first aspect, in some embodiments of the present application, the preparation method of the Fe atomic cluster coupled Mn-Fe double monatomic catalyst comprises the steps of preparing a Mn-doped precursor, obtaining a Mn monatomic catalyst and anchoring Fe monatomic and coupling Fe atomic clusters.

[0062] In combination with the first aspect, in some embodiments of the present application, the preparation method of the Fe atomic cluster coupled Mn-Fe double monatomic catalyst comprises the following steps:

[0063] (1) Respectively, accurately prepare dimethylformamide solution containing 50-150 mM dimethylimidazole solution, and 25-75 mM zinc nitrate hexahydrate and 2-20 mM manganese acetate dihydrate solution, then slowly mix the above two solutions, and the process needs to be magnetically stirred for 15 min-120 min to ensure uniform mixing of the solution. The mixed solution is fully reacted at 30-120 °C for 8-24 h to obtain solid particles. The particles are recovered and washed by centrifugation at 6000-8000 r / min for 5-30 min, and the washing liquid is anhydrous ethanol. Then dry at 30-80 °C to obtain solid precursors;

[0064] (2) The precursor is subjected to high-temperature heat treatment under inert gas protection at 800-1200 °C for 30-150 min at a heating rate of 1-10 °C / min. The product obtained by heat treatment is subjected to acid etching treatment, the acid concentration is 0.01-1.0 M, the treatment time is 1-5 h, and the treatment temperature is 30-100 °C. The treated sample is recovered and washed by centrifugation at 6000-8000 r / min for 5-30 min, and the washing liquid is deionized water. Then dry at 30-80 °C to obtain a solid powder;

[0065] (3) The above solid powder is subjected to high-temperature heat treatment under inert gas protection at 800-1200 °C for 30-150 min at a heating rate of 1-10 °C / min. The product obtained by heat treatment is ultrasonically dispersed in 0-100% isopropanol solution, and ferrous chloride and cyanamide are added, followed by magnetic stirring and ultrasonic dispersion treatment, for 10-180 min. The ratio of ferrous chloride to cyanamide is 1:(10-100). The treated sample is recovered and washed by centrifugation at 6000-8000 r / min for 5-30 min, and the washing liquid is deionized water. Then dry at 30-80 °C to obtain a solid powder. The solid is subjected to high-temperature heat treatment under inert gas protection at 800-1200 °C for 30-150 min at a heating rate of 1-10 °C / min to obtain Fe atomic cluster coupled Mn-Fe double-atom nanocatalyst.

[0066] Specifically, step (1) is to prepare a catalyst precursor. In step (1):

[0067] The role of the dimethylformamide solution is a reaction solvent.

[0068] The role of the dimethylimidazole solution is an N ligand.

[0069] The role of the zinc nitrate hexahydrate is that zinc nitrate and dimethylimidazole can be self-grown into a metal-organic framework structure precursor, and the subsequent Mn will replace the Zn in the precursor to make the Mn doped into the precursor.

[0070] The role of the manganese acetate dihydrate is to provide a metal Mn source.

[0071] The role of the reaction occurring in the slow mixing of the above two solutions is to prepare a Mn-doped precursor.

[0072] The obtained solid particulate is a Mn-doped precursor.

[0073] The role of step (2) is to obtain a Mn monatomic catalyst. In step (2):

[0074] The role of the high-temperature heat treatment is to reduce the Mn ions to form Mn monatomic.

[0075] The role of the acid etching treatment is to remove impurities.

[0076] The obtained solid powder is a Mn monatomic material.

[0077] The role of step (3) is to continue to anchor Fe monatomic and couple Fe atomic clusters on the basis of the Mn monatomic catalyst obtained in step (2). In step (3):

[0078] The role of the high-temperature heat treatment is to repair the carbon structure.

[0079] The role of the ferrous chloride is to provide a metal Fe source.

[0080] The role of the cyanamide is to provide an N source.

[0081] The obtained solid powder is a Fe atomic cluster coupled Mn-Fe bi-monatomic nanocatalyst precursor.

[0082] The role of the high-temperature heat treatment of the solid under inert gas protection is to reduce the Fe ions to form Fe monatomic.

[0083] The concept and technical effects of the present application will be described clearly and completely in combination with the embodiments below, so as to fully understand the purposes, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0084] In the description of the application, the description of the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In this specification, the exemplary description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0085] Unless otherwise specified, "room temperature" in the present application means 25°C ± 5°C.

[0086] Unless otherwise specified, "about" in the present application means that the allowable error is within ± 2%.

[0087] Unless otherwise specified, the specific conditions in the examples are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market.

[0088] Example 1

[0089] An Fe atomic cluster coupled Mn-Fe double monatomic nanocatalyst was prepared, and the specific preparation method was as follows:

[0090] (1) A certain amount of dimethylimidazole solution and a certain amount of zinc nitrate hexahydrate and manganese acetate dihydrate solution were accurately prepared in dimethylformamide solution, respectively, and the molar ratio of dimethylimidazole: zinc nitrate hexahydrate: manganese acetate dihydrate was 20:10:1. Then the above two solutions were slowly mixed uniformly, and magnetic stirring was carried out during the process, and the stirring time was 60 min to ensure uniform mixing of the solution. The mixed solution was fully reacted at 30°C, and the reaction time was 24 h to obtain solid particulate matter. The particulate matter was recovered and washed by centrifugation at a speed of 8000 r / min for 30 min, and the washing liquid was anhydrous ethanol. Then drying treatment was carried out at a drying temperature of 30°C to obtain a solid precursor;

[0091] (2) The precursor was subjected to high-temperature heat treatment under N2 protection, the heat treatment temperature was 1200°C, the heat treatment time was 30 min, and the heating rate was 10°C / min. The product obtained by heat treatment was subjected to acid etching treatment, the acid concentration was 1.0M, the treatment time was 1h, the treatment temperature was 30°C, and the treated sample was recovered and washed by centrifugation at a speed of 8000 r / min for 30 min, and the washing liquid was deionized water. Then drying treatment was carried out at a drying temperature of 30°C to obtain a solid powder;

[0092] (3) The solid powder is subjected to high-temperature heat treatment under N2 protection, the heat treatment temperature is 1200°C, the heat treatment time is 30 min, and the heating rate is 1°C / min. The product obtained by heat treatment is ultrasonically dispersed in a 100% isopropanol solution, ferrous chloride and cyanamide are added, magnetic stirring and ultrasonic dispersion treatment are sequentially performed, the treatment time is 180 min, and the ratio of ferrous chloride to cyanamide is 1:10. The treated sample is subjected to centrifugal recovery and washing treatment, the centrifugal speed is 8000 r / min, the treatment time is 30 min, and the washing liquid is deionized water. Then, drying treatment is performed at a drying temperature of 80°C to obtain a solid powder. The solid is subjected to high-temperature heat treatment under N2 protection, the heat treatment temperature is 1200°C, the heat treatment time is 150 min, and the heating rate is 10°C / min. The Fe atomic cluster coupled Mn-Fe double monatomic nanocatalyst prepared by the process is a black powder, the content ratio of Mn atoms to Fe atoms is 1:3, the specific surface area is 1196 m 2 / g.

[0093] The method can realize directional regulation of the properties of the catalyst structure and active sites by regulating the dosing amount of Mn and Fe in the precursor, the heat treatment temperature, the heating rate and other synthesis parameters.

[0094] Example 2

[0095] The catalyst prepared in Example 1 is used to catalyze the ozone degradation of organic micro-pollutants in water, and the specific method is implemented according to the following steps:

[0096] The Fe atomic cluster coupled Mn-Fe double monatomic nanocatalyst and the actual water containing refractory organic micro-pollutants are sequentially quantitatively added to the ozone catalytic reaction device, fully stirred and subjected to ozone aeration, and after sufficient reaction, the mixed effluent is filtered to recover the solid catalyst in the water for subsequent use.

[0097] Ozone gas is generated by an ozone generator and is subjected to aeration treatment by using an aeration head, the gas-phase ozone concentration is 15 mg / L, the flow rate of the ozone gas is 250 mL / min. The residence time is 600 s, the catalyst dosage is 50 mg / L, and the organic micro-pollutants to be treated include nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole, and the concentration of each is 5 mgC / L.

[0098] The results are shown in Figures 1 to 7 .

[0099] Figure 1 The degradation curves of nitrobenzene by ozone oxidation alone and ozone catalytic oxidation are shown in Figure 1It can be seen from the figure that the traditional ozone oxidation process can only achieve 55% removal of nitrobenzene within 300s, while the catalytic ozone oxidation process can achieve more than 80% removal of nitrobenzene within 300s, which shows that the Fe atomic cluster coupled with Mn-Fe double monatomic catalytic ozone degradation of nitrobenzene in water has a better effect than the ozone oxidation alone.

[0100] Figure 2 The degradation curves of p-hydroxybenzoic acid by ozone oxidation alone and catalytic ozone oxidation are shown in the figure. Figure 2 It can be seen from the figure that the traditional ozone oxidation process can only achieve less than 50% removal of p-hydroxybenzoic acid within 120s, while the catalytic ozone oxidation process can achieve more than 90% removal of p-hydroxybenzoic acid within 120s, which shows that the Fe atomic cluster coupled with Mn-Fe double monatomic catalytic ozone degradation of p-hydroxybenzoic acid in water has a better effect than the ozone oxidation alone.

[0101] Figure 3 The degradation curves of 4-nitrophenol by ozone oxidation alone and catalytic ozone oxidation are shown in the figure. Figure 3 It can be seen from the figure that the traditional ozone oxidation process can only achieve less than 50% removal of 4-nitrophenol within 120s, while the catalytic ozone oxidation process can achieve nearly 90% removal of 4-nitrophenol within 120s, which shows that the Fe atomic cluster coupled with Mn-Fe double monatomic catalytic ozone degradation of 4-nitrophenol in water has a better effect than the ozone oxidation alone.

[0102] Figure 4 The degradation curves of benzotriazole by ozone oxidation alone and catalytic ozone oxidation are shown in the figure. Figure 4 It can be seen from the figure that the traditional ozone oxidation process can only achieve 60% removal of benzotriazole within 600s, while the catalytic ozone oxidation process can achieve 90% removal of benzotriazole within 600s, which shows that the Fe atomic cluster coupled with Mn-Fe double monatomic catalytic ozone degradation of benzotriazole in water has a better effect than the ozone oxidation alone.

[0103] Figure 5 The results of the influence of different anions on the catalytic ozone oxidation degradation of nitrobenzene are shown in the figure. Figure 5 It can be seen from the figure that various water quality coexisting anions, such as Cl - , SO4 2- , H2PO4 2- , HCO3 - , have no obvious influence on the Fe atomic cluster coupled with Mn-Fe double monatomic catalytic ozone degradation of nitrobenzene in water, which shows that the method has obvious anti-water quality anion interference ability.

[0104] Figure 6The results of the influence of different concentrations of dissolved organic matter on catalytic ozone oxidation degradation of nitrobenzene are shown in Table 1. Figure 6 As can be seen from Table 1, different concentrations of dissolved organic matter have no obvious influence on the Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone degradation of nitrobenzene in water of the present application, which shows that the method of the present application has obvious anti-interference ability of water quality macromolecular organic matter.

[0105] Figure 7 The results of the influence of different water quality pH conditions on catalytic ozone oxidation degradation of nitrobenzene are shown in Table 2. Figure 7 As can be seen from Table 2, different water quality pH conditions have no obvious influence on the Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone degradation of nitrobenzene in water of the present application, which shows that the method of the present application has excellent application effect in acidic, neutral and alkaline environments.

[0106] Example 3

[0107] The catalyst prepared in Example 1 is used for deep treatment of drinking water, and the ozone-biological activated carbon process in the drinking water deep treatment process can be replaced by the Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone oxidation process, so as to realize effective removal of refractory organic micro-pollutants in water, and at the same time, ozone has the effects of sterilization, disinfection and algae removal, etc., thereby ensuring water supply safety.

[0108] Example 4

[0109] The catalyst prepared in Example 1 is used for deep treatment of reclaimed water, and Fe atomic cluster coupled Mn-Fe double monatomic catalytic ozone oxidation treatment is carried out after the process of effluent from the secondary sedimentation tank, so as to realize effective removal of refractory organic micro-pollutants in water and ensure the quality of effluent.

[0110] Example 5

[0111] The catalyst prepared in Example 1 is used for effective treatment of industrial wastewater, such as pharmaceutical wastewater, printing and dyeing wastewater, aquaculture wastewater and other wastewater rich in refractory organic micro-pollutants. Such wastewater is often difficult to be treated by conventional biochemical treatment. The process can effectively degrade refractory organic micro-pollutants in water, reduce organic matter in effluent and at the same time improve the biodegradability, thereby realizing efficient treatment of process wastewater.

[0112] Finally, it needs to be further pointed out that based on the electronic structure of ozone, ozone has strong oxidizing property, is more likely to combine with reductive sites, and through electron transfer, the ozone molecule obtains electrons, and the ozone that obtains electrons will no longer be stable, that is, will quickly decompose into active oxygen species. The Mn and Fe single atom sites in the Mn-N and Fe-N coordination configuration constructed by the application are just reductive (because the electronegativity of N is higher than that of Mn and Fe), in addition, coupling the Fe atom cluster can further change the electron distribution of the Mn and Fe single atom sites, so that they are more likely to interface adsorb and catalyze ozone. Therefore, the application directionally synthesizes the interface atomic coordination configuration matched with the electronic structure of ozone.

[0113] The method of the application can achieve 70% to 90% removal of the above-mentioned refractory organic micro-pollutants such as nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole in 120s when treating water rich in 5mgC / L of the refractory organic micro-pollutants, and compared with the traditional ozone oxidation process, the removal effect of the process on nitrobenzene, p-hydroxybenzoic acid, 4-nitrophenol and benzotriazole is increased by 15.72 times, 8.14 times, 6.39 times and 6.91 times respectively. In addition, the method has good performance stability and anti-interference in the process of treating refractory organic pollutants, and the removal performance of the refractory organic micro-pollutant nitrobenzene will not be interfered by various anions in water, including 5mM of Cl - , SO4 2- , H2PO4 2- , HCO3 - ; the performance will also not be interfered by dissolved organic matter (2mgC / L or 5mgC / L) in water. Under the condition of different water quality pH (pH range: 3-9), the method shows excellent nitrobenzene removal performance.

[0114] The application has been described in detail in combination with the embodiments above, but the application is not limited to the above embodiments, and various changes can be made within the knowledge range possessed by those skilled in the art without departing from the purpose of the application.

Claims

1. A method for the degradation of organic micropollutants in water by ozone through Fe cluster coupling with Mn-Fe dual single-atom catalysis, characterized in that, The method includes the step of adding Fe cluster coupled with Mn-Fe dual single-atom catalyst and water to be treated into an ozone catalytic reaction device for ozone aeration. The Fe cluster-coupled Mn-Fe dual single-atom catalyst was prepared through the following steps: S1: Prepare an N-ligand solution and a solution containing zinc nitrate hexahydrate and Mn source in the reaction solvent. Mix the two solutions and react them to obtain solid particles, which are Mn-doped precursors. S2: After the Mn-doped precursor is heat-treated for the first time, it is acid-etched to obtain a Mn single-atom catalyst; S3: After the Mn single-atom catalyst is heat-treated for the second time, the product is dispersed in a solvent, Fe source and N source are added, and after the reaction, the sample is centrifuged, washed and dried. The obtained solid product is heat-treated for the third time under an inert atmosphere to obtain the Fe atom cluster coupled Mn-Fe dual single-atom catalyst.

2. The method according to claim 1, characterized in that, The method also includes the step of filtering the effluent after ozone aeration to recover the solid catalyst in the water.

3. The method according to claim 1, characterized in that, In step S1, the reaction solvent includes a dimethylformamide solution; and / or, the N-ligand solution includes a 50-150 mmol / L dimethylimidazole solution; and / or, the concentration of zinc nitrate hexahydrate is 25-75 mmol / L; and / or, the Mn source includes a 2-20 mmol / L manganese acetate dihydrate solution; and / or, the temperature of the mixed reaction is 30℃-120℃; and / or, the time of the mixed reaction is 8 h-24 h.

4. The method according to claim 1, characterized in that, In step S2, the concentration of the acid solution used for acid etching is 0.01~1.0 mol / L; and / or, the processing time for acid etching is 1 h~5 h; and / or, the processing temperature for acid etching is 30℃~100℃.

5. The method according to claim 1, characterized in that, In step S3, the Fe source includes ferrous chloride; and / or, the N source includes cyanamide; and / or, the atomic ratio of the Fe source to the N source is 1:10~100.

6. The method according to any one of claims 1 to 5, characterized in that, The temperature of the first heat treatment is 800~1200℃; and / or the time of the first heat treatment is 30 min~150 min; and / or the heating rate of the first heat treatment is 1 ℃ / min~10 ℃ / min.

7. The method according to any one of claims 1 to 5, characterized in that, The temperature of the second heat treatment is 800~1200℃; and / or the time of the second heat treatment is 30 min~150 min; and / or the heating rate of the second heat treatment is 1 ℃ / min~10 ℃ / min.

8. The method according to any one of claims 1 to 5, characterized in that, The temperature of the third heat treatment is 800~1200℃; and / or the time of the third heat treatment is 30 min~150 min; and / or the heating rate of the third heat treatment is 1 ℃ / min~10 ℃ / min.

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