Method for controlling disinfection by-products in drinking water by catalytic ozonation

Abstract

The application provides a method for controlling disinfection by-products in drinking water by ozone catalytic oxidation. The method effectively utilizes the high catalytic activity of manganese monatomic sites in a manganese double monatomic carbon-based catalyst, effectively degrades dissolved organic matter in water through specific interface catalytic ozonation, removes key precursors of disinfection by-products (DBPs), effectively reduces the generation amount of C-DBPs and N-DBPs in the post-chlorination disinfection process, and guarantees the safety of drinking water supply.

Description

Technical Field

[0001] This invention belongs to the field of drinking water treatment technology, specifically relating to a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. Background Technology

[0002] Dissolved organic matter (DOM) is a class of organic mixtures with complex composition, structure, and environmental behavior, widely present in various aquatic environments. In actual water treatment processes, DOM reacts with disinfectants (such as free chlorine) to generate toxic disinfection byproducts (DBPs), posing a significant threat to drinking water safety. DOM removal is an effective method to control the formation of harmful DBPs. However, traditional drinking water treatment processes (coagulation / flocculation-sedimentation-filtration) are ineffective at removing DOM. Therefore, there is an urgent need to develop novel and efficient advanced drinking water treatment technologies to effectively remove DBP precursors.

[0003] Some water treatment plants have adopted ozone oxidation as a pre-oxidation or advanced treatment process to enhance effluent quality. However, ozone not only struggles to effectively reduce DOM concentration, but it also rapidly converts DOM into oxygen-containing intermediates such as ketones, aldehydes, and carboxylic acids, which are important precursors to DBPs (dichloropropane-1,2-dimethylformyl chloride). For example, ozone can oxidize olefins in DOM to ketones or aldehydes, leading to a significant increase in the formation of 1,1,1-trichloroacetone and chloral hydrate during subsequent chlorination. Ozone can also oxidize amines to nitro compounds, the so-called trichloronitromethane precursors.

[0004] Heterogeneous catalytic ozone oxidation can rapidly decompose ozone into highly oxidizing reactive oxygen species, such as hydroxyl radicals (·OH, 2.70V) and surface atomic oxygen (*Oad, 2.43V), within a short time. These reactive oxygen species can achieve rapid removal and even mineralization of recalcitrant organic pollutants in water. However, the structurally complex DOM (domestic organic compounds) inevitably undergoes conversion into key intermediates of DBPs, such as ketones, aldehydes, and nitro-containing compounds, during catalytic ozone oxidation, leading to the accumulation of DBP precursors. For example, some researchers have found that Fe-Cu-MCM-41 catalytic ozone oxidation increases the formation of trihalomethanes and halocarboxylic acids by 644% and 2200%, respectively. Other researchers have found that LaCoO3 catalytic ozone oxidation produces more trihalomethane precursors compared to traditional ozone oxidation processes. In conclusion, there is an urgent need to develop a method for constructing highly active catalysts that can efficiently degrade DBP precursors based on the formation mechanism of DBPs, and to develop a method for efficiently controlling the formation of DBPs in drinking water. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. This method effectively utilizes the highly catalytically active manganese single-atom sites in a manganese dual-single-atom carbon-based catalyst to effectively degrade DOM in water and remove key intermediates of DBPs through specific interfacial catalytic ozonation, thereby effectively reducing the generation of C-DBPs and N-DBPs during post-chlorination disinfection and ensuring the safety of drinking water supply.

[0006] The first aspect of the present invention provides a method for controlling disinfection byproducts in drinking water by ozone catalytic oxidation, comprising the steps of mixing a manganese bis-single-atom carbon-based catalyst and water to be treated and then introducing ozone gas to carry out the reaction.

[0007] One technical solution of the present invention regarding the method for controlling disinfection byproducts in drinking water by ozone catalytic oxidation has at least the following beneficial effects:

[0008] The present invention provides a method for controlling disinfection byproducts in drinking water by ozone catalytic oxidation, which can rapidly remove various carbon / nitrogen disinfection byproduct (C-DBPs / N-DBPs) precursors, and can completely remove precursors of highly toxic trichloronitromethane (TCNM).

[0009] Furthermore, this method can also achieve efficient removal of bromine disinfection byproducts (Br-DBPs) precursors during the treatment of bromine-containing water. The ozone catalytic oxidation method for controlling disinfection byproducts in drinking water in this invention is fundamentally different from conventional ozone catalytic oxidation methods for controlling DBPs. Unlike previous methods that simply enhanced ozone oxidation, this method is based on the DBPs formation mechanism. It utilizes advanced single-atom catalytic technology to directionally regulate the electron configuration and microstructure of the catalyst surface, and leverages the synergistic effect between the two Mn single-atom sites to significantly improve the generation efficiency of reactive oxygen species and the efficient removal of key DBPs intermediates, greatly avoiding the accumulation of key DBPs precursors.

[0010] This invention discloses a method for controlling disinfection byproducts in drinking water using ozone catalytic oxidation. When treating surface water rich in DOM (dichloroform), the generation of C-DBPs and N-DBPs can be reduced by up to 70% and 87%, respectively, under the catalytic ozonation of a manganese-based dual-monoatomic catalyst. Compared to traditional ozone oxidation processes, this process improves the control effect on C-DBP and N-DBP generation by 51% and 319%, respectively. Specifically, the generation of C-DBPs such as chloroform (TCM), trichloroacetone (TCP), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA) can be effectively controlled, as can the generation of N-DBPs such as dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), and trichloronitromethane (TCNM). The generation of Br-DBPs can be reduced by up to 71% under the catalytic ozonation of the manganese-based dual-monoatomic catalyst, which is 1.5 times the control effect of traditional ozone oxidation processes. The generation amounts of Br-DBPs, including bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM), dibromochloroacetaldehyde (DBCAL), bromochloroacetic acid (BCAA), dibromoacetic acid (DBAA), bromochloroacetonitrile (BCAN), and dibromoacetonitrile (DBAN), can all be effectively controlled.

[0011] This invention provides a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. It is applicable to the advanced treatment of urban drinking water plants, features simple operation, and considers that many drinking water plants already possess the key structures required for ozone oxidation processes; upgrading existing processes can be achieved simply by adding an ozone catalyst. Furthermore, this process is also suitable for high-end residential communities, large shopping malls, airports, train stations, ecological parks, and other similar settings for producing high-quality drinking water.

[0012] According to some embodiments of the present invention, the dosage of the manganese bis-single-atom carbon-based catalyst is 0.05 g / L to 0.25 g / L.

[0013] According to some embodiments of the present invention, the reaction time for introducing ozone gas is 5 min to 30 min.

[0014] According to some embodiments of the present invention, the dosage of gaseous ozone is 2 to 15 mg / L.

[0015] According to some embodiments of the present invention, the ozone flow rate for the reaction is 100 mL / min to 300 mL / min.

[0016] According to some embodiments of the present invention, after ozone gas is introduced for reaction, the treated mixed solution is filtered to recover the catalyst in the reactor for reuse, and the filtrate is disinfected with chlorine.

[0017] According to some embodiments of the present invention, ozone gas is introduced while the mixture is thoroughly stirred.

[0018] According to some embodiments of the present invention, the water to be treated is actual surface water containing DOM.

[0019] According to some embodiments of the present invention, the method of the present invention can be carried out in an ozone contact reactor.

[0020] According to some embodiments of the present invention, the dosage of the manganese dual single-atom carbon-based catalyst is 0.05 g / L to 0.25 g / L.

[0021] According to some embodiments of the present invention, the preparation method of the manganese dual single-atom carbon-based catalyst includes the following steps:

[0022] S1: Add divalent zinc source and trivalent manganese source to dimethylformamide solution and mix to obtain solution A;

[0023] S2: Dimethylimidazole is added to a dimethylformamide solution and mixed to obtain solution B;

[0024] S3: Mix and react the solutions A and B to obtain manganese-doped ZIF-8 nanocrystals;

[0025] S4: Manganese-doped ZIF-8 nanocrystals were subjected to a first high-temperature heat treatment under a protective atmosphere to obtain Mn and N co-doped nanocarbon.

[0026] S5: The Mn and N co-doped nano-carbon is acid-treated for 3-6 hours, thoroughly dried, and then subjected to a second high-temperature heat treatment under a protective atmosphere to obtain a manganese single-atom carbon-based catalyst.

[0027] S6: Add the manganese single-atom carbon-based catalyst, manganese source and nitrogen source into a solvent and stir ultrasonically to collect solid particles;

[0028] S7: The solid particles are subjected to a third high-temperature heat treatment under a protective atmosphere to obtain the manganese double single-atom carbon-based catalyst.

[0029] This invention employs a defect-anchored coupled nanoscale spatial confinement method to directionally construct a manganese-based dual-single-atom carbon catalyst. The catalyst exhibits a Mn single-atom loading of 0–2 at%, and a specific surface area of ​​1000 m². 2 / g~1200m 2The coordination numbers of Mn and N atoms range from 0 to 4 per g. This catalyst is simple to synthesize and exhibits high structural and performance stability. Its large specific surface area and abundant nanopores provide an excellent reaction platform and space for interfacial catalytic ozonation. The directionally regulated interfacial electronic structure and the synergistic catalytic effect between the two Mn single-atom sites enable highly efficient catalysis of ozone, significantly improving the catalytic efficiency of ozone formation.

[0030] According to some embodiments of the present invention, in step S1, the divalent zinc source includes at least one of zinc nitrate, zinc acetate, or their hydrates.

[0031] According to some embodiments of the present invention, in step S1, the trivalent manganese source includes at least one of manganese acetate and manganese chloride.

[0032] According to some embodiments of the present invention, in step S1, Zn 2+ With Mn 3+ The molar concentration ratio is (2-10):1.

[0033] According to some embodiments of the present invention, in step S1, during the mixing process of adding the divalent zinc source and the trivalent manganese source to the dimethylformamide solution, stirring is performed. The stirring time can be 15 minutes.

[0034] The role of dimethylformamide is as a reaction solvent.

[0035] According to some embodiments of the present invention, in step S2, dimethylimidazole is added to a dimethylformamide solution for mixing, and the molar ratio of dimethylimidazole to divalent zinc source can be 2:1.

[0036] According to some embodiments of the present invention, in step S2, during the mixing process of adding dimethylimidazole to the dimethylformamide solution, stirring is performed. The stirring time can be 15 minutes.

[0037] The role of dimethylimidazole is to provide ligands.

[0038] According to some embodiments of the present invention, in step S3, the mixing reaction time is 24h to 48h.

[0039] According to some embodiments of the present invention, in step S3, the temperature of the mixing reaction is 25°C to 120°C.

[0040] According to some embodiments of the present invention, in step S3, the manganese-doped ZIF-8 nanocrystals are denoted as Mn-ZIF-8.

[0041] According to some embodiments of the present invention, in step S4, before the first high-temperature heat treatment, Mn-ZIF-8 is centrifuged for recovery, and the crystal particles are thoroughly cleaned with anhydrous ethanol and deionized water and then dried.

[0042] According to some embodiments of the present invention, in step S4, the temperature of the first high-temperature heat treatment is 1000℃~1200℃.

[0043] According to some embodiments of the present invention, the duration of the first high-temperature heat treatment is 0.5h to 1.5h.

[0044] According to some embodiments of the present invention, the heating rate of the first high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0045] According to some embodiments of the present invention, in step S5, the acid treatment time is 3h to 6h, and the product is dried before the second high-temperature heat treatment after the acid treatment.

[0046] According to some embodiments of the present invention, in step S5, the temperature of the second high-temperature heat treatment is 900℃~1100℃.

[0047] According to some embodiments of the present invention, in step S5, the duration of the second high-temperature heat treatment is 3.5h to 3h.

[0048] According to some embodiments of the present invention, in step S5, the heating rate of the second high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0049] According to some embodiments of the present invention, the manganese single-atom carbon-based catalyst obtained in step S5 is denoted as Mn-NC.

[0050] According to some embodiments of the present invention, in step S6, the manganese single-atom carbon-based catalyst, manganese source, and cyanamide are added to a solvent, stirred, and sonicated, and the solid particles are collected. The solvent is an aqueous solution of isopropanol.

[0051] According to some embodiments of the present invention, in step S6, magnetic stirring is performed first, followed by ultrasonic treatment.

[0052] According to some embodiments of the present invention, in step S6, the magnetic stirring time is 10 min to 30 min.

[0053] According to some embodiments of the present invention, in step S6, the ultrasonic treatment time is 1h to 3h.

[0054] According to some embodiments of the present invention, in step S6, after ultrasonic treatment and sufficient adsorption, the solid particles are collected.

[0055] According to some embodiments of the present invention, in step S6, the manganese source includes at least one of manganese chloride, manganese acetate, manganese sulfate, and manganese nitrate.

[0056] According to some embodiments of the present invention, in step S6, the nitrogen source includes at least one of cyanamide, melamine, uric acid, and dicyandiamide.

[0057] According to some embodiments of the present invention, in step S6, the molar concentration ratio of nitrogen source to manganese source is (5-10):1.

[0058] According to some embodiments of the present invention, in step S7, the temperature of the third high-temperature heat treatment is 1000℃~1200℃.

[0059] According to some embodiments of the present invention, in step S7, the time for the third high-temperature heat treatment is 0.5h to 1.5h.

[0060] According to some embodiments of the present invention, in step S7, the heating rate of the third high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0061] According to some embodiments of the present invention, in step S7, the manganese bis-single-atom carbon-based catalyst obtained is denoted as Mn-Mn-NC.

[0062] Compared to the manganese single-atom carbon-based catalyst Mn-NC, the difference between the manganese dual single-atom carbon-based catalyst lies in the synergistic effect between different Mn single-atom sites brought about by the richer Mn single-atom loading.

[0063] According to some embodiments of the present invention, in the preparation method of the manganese dual single-atom carbon-based catalyst, the protective atmosphere includes nitrogen.

[0064] The preparation method of manganese dual single-atom carbon-based catalyst does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0065] According to some embodiments of the present invention, in the manganese dual single-atom carbon-based catalyst Mn-Mn-NC, the loading of Mn single atoms is 0 to 2 at%.

[0066] According to some embodiments of the present invention, the manganese dual single-atom carbon-based catalyst Mn-Mn-NC has a specific surface area of ​​1000 m². 2 / g~1200m 2 / g.

[0067] According to some embodiments of the present invention, in the manganese bis-monocarbon-based catalyst Mn-Mn-NC, the coordination number of Mn and N atoms is 0 to 4.

[0068] This invention relates to a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. This method is applied to advanced drinking water treatment, replacing the ozone-biological activated carbon process in advanced drinking water treatment with a manganese-based double single-atom carbon catalyst catalytic ozone oxidation process. This achieves effective removal of disinfection byproduct precursors and ensures safe water supply.

[0069] This invention relates to a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. It can be applied in large-scale settings such as high-end residential communities, large shopping malls, airports, train stations, and ecological parks to prepare high-quality drinking water. The active oxygen species generated by the manganese dual single-atom carbon-based catalyst can easily degrade high-risk pollutants in the water, effectively remove toxic byproduct precursors, and also have bactericidal functions, thus fully ensuring the safety of drinking water. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of the water treatment process.

[0071] Figure 2 The graphs show the changes in dissolved organic carbon concentration over time during ozone oxidation and catalytic ozone oxidation of DOM-rich aqueous solutions.

[0072] Figure 3 This diagram illustrates the formation of various DBPs before and after ozone oxidation treatment of actual surface water.

[0073] Figure 4 A diagram showing the formation of various DBPs before and after catalytic ozone oxidation treatment of actual surface water. Detailed Implementation

[0074] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0075] In some embodiments of the present invention, a method for controlling disinfection byproducts in drinking water by ozone catalytic oxidation is provided, comprising the steps of mixing a manganese bis-single-atom carbon-based catalyst and water to be treated and then introducing ozone gas to carry out the reaction.

[0076] It is understood that the ozone catalytic oxidation method of the present invention for controlling disinfection byproducts in drinking water can achieve rapid removal of various carbon / nitrogen disinfection byproduct (C-DBPs / N-DBPs) precursors, and can completely remove precursors of highly toxic trichloronitromethane (TCNM).

[0077] Furthermore, this method can also achieve efficient removal of bromine disinfection byproducts (Br-DBPs) precursors during the treatment of bromine-containing water. The ozone catalytic oxidation method for controlling disinfection byproducts in drinking water in this invention is fundamentally different from conventional ozone catalytic oxidation methods for controlling DBPs. Unlike previous methods that simply enhanced ozone oxidation, this method is based on the DBPs formation mechanism. It utilizes advanced single-atom catalytic technology to directionally regulate the electron configuration and microstructure of the catalyst surface, and leverages the synergistic effect between the two Mn single-atom sites to significantly improve the generation efficiency of reactive oxygen species and the efficient removal of key DBPs intermediates, greatly avoiding the accumulation of key DBPs precursors.

[0078] This invention discloses a method for controlling disinfection byproducts in drinking water using ozone catalytic oxidation. When treating surface water rich in DOM (dichloroform), the generation of C-DBPs and N-DBPs can be reduced by up to 70% and 87%, respectively, under the catalytic ozonation of a manganese-based dual-monoatomic catalyst. Compared to traditional ozone oxidation processes, this process improves the control effect on C-DBP and N-DBP generation by 51% and 319%, respectively. Specifically, the generation of C-DBPs such as chloroform (TCM), trichloroacetone (TCP), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA) can be effectively controlled, as can the generation of N-DBPs such as dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), and trichloronitromethane (TCNM). The generation of Br-DBPs can be reduced by up to 71% under the catalytic ozonation of the manganese-based dual-monoatomic catalyst, which is 1.5 times the control effect of traditional ozone oxidation processes. The generation amounts of Br-DBPs, including bromodichloromethane (BDCM), dibromochloromethane (DBCM), tribromomethane (TBM), dibromochloroacetaldehyde (DBCAL), bromochloroacetic acid (BCAA), dibromoacetic acid (DBAA), bromochloroacetonitrile (BCAN), and dibromoacetonitrile (DBAN), can all be effectively controlled.

[0079] This invention provides a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. It is applicable to the advanced treatment of urban drinking water plants, features simple operation, and considers that many drinking water plants already possess the key structures required for ozone oxidation processes; upgrading existing processes can be achieved simply by adding an ozone catalyst. Furthermore, this process is also suitable for high-end residential communities, large shopping malls, airports, train stations, ecological parks, and other similar settings for producing high-quality drinking water.

[0080] In some embodiments of the present invention, the dosage of the manganese bis-single-atom carbon-based catalyst is 0.05 g / L to 0.25 g / L.

[0081] In some embodiments of the present invention, the reaction time for introducing ozone gas is 5 min to 30 min.

[0082] In some embodiments of the present invention, the dosage of gaseous ozone is 2 to 15 mg / L.

[0083] In some embodiments of the present invention, the ozone flow rate for the reaction is 100 mL / min to 300 mL / min.

[0084] In some embodiments of the present invention, after ozone gas is introduced for reaction, the treated mixed solution is filtered, the catalyst in the reactor is recovered for reuse, and the filtrate is disinfected with chlorine.

[0085] In some embodiments of the present invention, ozone gas is introduced while the mixture is thoroughly stirred.

[0086] In some embodiments of the present invention, the water to be treated is actual surface water containing DOM.

[0087] In some embodiments of the present invention, the method of the present invention can be carried out in an ozone contact reactor.

[0088] In some embodiments of the present invention, the dosage of the manganese bis-single-atom carbon-based catalyst is 0.05 g / L to 0.25 g / L.

[0089] In some embodiments of the present invention, the preparation method of the manganese dual single-atom carbon-based catalyst includes the following steps:

[0090] S1: Add divalent zinc source and trivalent manganese source to dimethylformamide solution and mix to obtain solution A;

[0091] S2: Dimethylimidazole is added to a dimethylformamide solution and mixed to obtain solution B;

[0092] S3: Mix and react solutions A and B to obtain manganese-doped ZIF-8 nanocrystals;

[0093] S4: Manganese-doped ZIF-8 nanocrystals were subjected to a first high-temperature heat treatment under a protective atmosphere to obtain Mn and N co-doped nanocarbon.

[0094] S5: Mn and N co-doped nano-carbon is acid-treated for 3-6 hours, thoroughly dried, and then subjected to a second high-temperature heat treatment under a protective atmosphere to obtain a manganese single-atom carbon-based catalyst.

[0095] S6: Add manganese single-atom carbon-based catalyst, manganese source and nitrogen source to solvent and stir ultrasonically to collect solid particles;

[0096] S7: The solid particles were subjected to a third high-temperature heat treatment under a protective atmosphere to obtain a manganese-based dual single-atom carbon catalyst.

[0097] This invention employs a defect-anchored coupled nanoscale spatial confinement method to directionally construct a manganese-based dual-single-atom carbon catalyst. The catalyst exhibits a Mn single-atom loading of 0–2 at%, and a specific surface area of ​​1000 m². 2 / g~1200m 2 The coordination numbers of Mn and N atoms range from 0 to 4 per g. This catalyst is simple to synthesize and exhibits high structural and performance stability. Its large specific surface area and abundant nanopores provide an excellent reaction platform and space for interfacial catalytic ozonation. The directionally regulated interfacial electronic structure and the synergistic catalytic effect between the two Mn single-atom sites enable highly efficient catalysis of ozone, significantly improving the catalytic efficiency of ozone formation.

[0098] In some embodiments of the present invention, in step S1, the divalent zinc source includes at least one of zinc nitrate, zinc acetate, or their hydrates.

[0099] In some embodiments of the present invention, in step S1, the trivalent manganese source includes at least one of manganese acetate and manganese chloride.

[0100] In some embodiments of the present invention, in step S1, Zn 2+ With Mn 3+ The molar concentration ratio is (2-10):1.

[0101] In some embodiments of the present invention, during step S1, the divalent zinc source and the trivalent manganese source are mixed in a dimethylformamide solution, and the mixture is stirred. The stirring time can be 15 minutes.

[0102] The role of dimethylformamide is as a reaction solvent.

[0103] In some embodiments of the present invention, in step S2, dimethylimidazole is added to a dimethylformamide solution for mixing, and the molar ratio of dimethylimidazole to divalent zinc source can be 2:1.

[0104] In some embodiments of the present invention, during step S2, the mixture of dimethylimidazole and dimethylformamide solution is stirred. The stirring time may be 15 minutes.

[0105] The role of dimethylimidazole is to provide ligands.

[0106] In some embodiments of the present invention, in step S3, the mixing reaction time is 24h to 48h.

[0107] In some embodiments of the present invention, in step S3, the temperature of the mixing reaction is 25°C to 120°C.

[0108] In some embodiments of the present invention, in step S3, the manganese-doped ZIF-8 nanocrystals are denoted as Mn-ZIF-8.

[0109] In some embodiments of the present invention, in step S4, before the first high-temperature heat treatment, Mn-ZIF-8 is centrifuged for recovery, and the crystal particles are thoroughly cleaned with anhydrous ethanol and deionized water and then dried.

[0110] In some embodiments of the present invention, in step S4, the temperature of the first high-temperature heat treatment is 1000℃~1200℃.

[0111] In some embodiments of the present invention, the duration of the first high-temperature heat treatment is 0.5h to 1.5h.

[0112] In some embodiments of the present invention, the heating rate of the first high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0113] In some embodiments of the present invention, in step S5, the acid treatment time is 3h to 6h, and the product is dried before the second high-temperature heat treatment after the acid treatment.

[0114] In some embodiments of the present invention, in step S5, the temperature of the second high-temperature heat treatment is 900°C to 1100°C.

[0115] In some embodiments of the present invention, in step S5, the second high-temperature heat treatment lasts for 3.5 hours to 3 hours.

[0116] In some embodiments of the present invention, in step S5, the heating rate of the second high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0117] In some embodiments of the present invention, the manganese single-atom carbon-based catalyst obtained in step S5 is denoted as Mn-NC.

[0118] In some embodiments of the present invention, in step S6, a manganese single-atom carbon-based catalyst, a manganese source, and cyanamide are added to a solvent, stirred, and sonicated, and the solid particles are collected. The solvent is an aqueous solution of isopropanol.

[0119] In some embodiments of the present invention, in step S6, magnetic stirring is performed first, followed by ultrasonic treatment.

[0120] In some embodiments of the present invention, in step S6, the magnetic stirring time is 10 min to 30 min.

[0121] In some embodiments of the present invention, in step S6, the ultrasonic treatment time is 1h to 3h.

[0122] In some embodiments of the present invention, in step S6, after ultrasonic treatment and full adsorption, the solid particles are collected.

[0123] In some embodiments of the present invention, in step S6, the manganese source includes at least one of manganese chloride, manganese acetate, manganese sulfate, and manganese nitrate.

[0124] In some embodiments of the present invention, in step S6, the nitrogen source includes at least one of cyanamide, melamine, uric acid, and dicyandiamide.

[0125] In some embodiments of the present invention, in step S6, the molar ratio of nitrogen source to manganese source is (5-10):1.

[0126] In some embodiments of the present invention, in step S7, the temperature of the third high-temperature heat treatment is 1000℃~1200℃.

[0127] In some embodiments of the present invention, in step S7, the time for the third high-temperature heat treatment is 0.5h to 1.5h.

[0128] In some embodiments of the present invention, in step S7, the heating rate of the third high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

[0129] In some embodiments of the present invention, the manganese bis-single-atom carbon-based catalyst obtained in step S7 is denoted as Mn-Mn-NC.

[0130] Compared to the manganese single-atom carbon-based catalyst Mn-NC, the difference between the manganese dual single-atom carbon-based catalyst lies in the synergistic effect between different Mn single-atom sites brought about by the richer Mn single-atom loading.

[0131] According to some embodiments of the present invention, in the preparation method of the manganese dual single-atom carbon-based catalyst, the protective atmosphere includes nitrogen.

[0132] The preparation method of manganese dual single-atom carbon-based catalyst does not require expensive equipment and complex process control, the reaction conditions are not harsh, the raw materials are readily available, the production cost is low, and it is easy to industrialize.

[0133] In some embodiments of the present invention, the loading of Mn single atoms in the manganese dual single-atom carbon-based catalyst Mn-Mn-NC is 0 to 2 at%.

[0134] In some embodiments of the present invention, the manganese dual single-atom carbon-based catalyst Mn-Mn-NC has a specific surface area of ​​1000 m². 2 / g~1200m 2 / g.

[0135] In some embodiments of the present invention, the coordination number of Mn and N atoms in the manganese bis-mono-atom carbon-based catalyst Mn-Mn-NC is 0 to 4.

[0136] This invention relates to a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. This method is applied to advanced drinking water treatment, replacing the ozone-biological activated carbon process in advanced drinking water treatment with a manganese-based double single-atom carbon catalyst catalytic ozone oxidation process. This achieves effective removal of disinfection byproduct precursors and ensures safe water supply.

[0137] This invention relates to a method for controlling disinfection byproducts in drinking water through ozone catalytic oxidation. It can be applied in large-scale settings such as high-end residential communities, large shopping malls, airports, train stations, and ecological parks to prepare high-quality drinking water. The active oxygen species generated by the manganese dual single-atom carbon-based catalyst can easily degrade high-risk pollutants in the water, effectively remove toxic byproduct precursors, and also have bactericidal functions, thus fully ensuring the safety of drinking water.

[0138] The technical solution of the present invention will be better understood below with reference to specific embodiments.

[0139] It should be noted that all reagents used in the examples were obtained from commercially available sources.

[0140] Example

[0141] A manganese-based dual single-atom carbon catalyst was first prepared, and the specific preparation method is as follows:

[0142] (1) Add zinc nitrate hexahydrate and manganese acetate dihydrate sequentially to the dimethylformamide solution, stir magnetically for 15 minutes to ensure thorough mixing, and label this solution A; wherein, Zn 2+ With Mn 3+ The concentration ratio is 10:1;

[0143] (2) Add dimethylimidazole to the dimethylformamide solution and stir magnetically for 15 minutes to ensure complete dissolution. Label this solution as solution B. The dimethylimidazole and Zn... 2+ The concentration ratio is 2:1;

[0144] (3) Mix solution A and solution B evenly and react for 24 hours at a reaction temperature of 120℃ to allow manganese-doped ZIF-8 (Mn-ZIF-8) nanocrystals to grow fully.

[0145] (4) The synthesized Mn-ZIF-8 nanocrystals were centrifuged and recovered. The crystal particles were thoroughly cleaned with anhydrous ethanol and deionized water and then dried.

[0146] (5) Mn-ZIF-8 was subjected to high-temperature heat treatment under nitrogen atmosphere protection to obtain Mn and N co-doped nano carbon; wherein the calcination temperature was 1100℃, the calcination time was 1.0h, and the heating rate was 5.0℃ / min.

[0147] (6) Mn and N co-doped nano-carbon was acid-treated for 3 h, and after being fully dried, it was subjected to high-temperature heat treatment under nitrogen atmosphere protection to obtain manganese single-atom carbon-based catalyst (Mn-NC); wherein the calcination temperature was 900℃, the calcination time was 3 h, and the heating rate was 5.0℃ / min.

[0148] (7) Mn-NC, manganese chloride and cyanamide were added sequentially to an isopropanol aqueous solution, magnetically stirred for 10 min, ultrasonically treated for 3 h, and the solid particles were collected after full adsorption; the ratio of cyanamide to magnesium chloride was 5:1.

[0149] (8) The solid particles collected in step (7) are subjected to high-temperature heat treatment under nitrogen atmosphere protection to obtain manganese double single-atom carbon-based catalyst (Mn-Mn-NC); wherein the calcination temperature is 1100℃, the calcination time is 1.0h, and the heating rate is 5.0℃ / min.

[0150] Then, the selected manganese dual single-atom carbon-based catalyst was a black powder, in which the loading of Mn single atoms was 1.68 at%, and the specific surface area was 1200 m². 2 / g, the coordination number of Mn and N atoms is 4.

[0151] It should be noted that this method can achieve targeted regulation of catalyst structure and active site properties by adjusting synthesis parameters such as the amount of Mn added in the precursor, heat treatment temperature, and heating rate.

[0152] The prepared manganese double single-atom carbon-based catalyst was used to control the generation of disinfection byproducts in drinking water through a catalytic ozone oxidation process.

[0153] Water treatment process reference Figure 1 As shown, the specific method is implemented according to the following steps:

[0154] The manganese-based dual-single-atom carbon catalyst and actual surface water containing DOM were quantitatively loaded into the ozone contact reactor (as shown in the attached diagram). Figure 1 As shown in the figure, ozone gas is introduced while stirring thoroughly. The residence time of the water sample to be treated in the ozone contact reactor is controlled between 5 min and 30 min. The treated mixed solution is then filtered to recover the catalyst in the reactor for reuse. The filtrate is then disinfected with chlorine.

[0155] The ozone gas is continuously added to the reaction liquid through an aeration head, with a gaseous ozone dosage of 15 mg / L and an ozone gas flow rate of 300 mL / min. The catalyst dosage is 0.25 g / L.

[0156] Figure 2 The graphs show the changes in dissolved organic carbon concentration over time during ozone oxidation alone and catalytic ozone oxidation of DOM-rich aqueous solutions. Figure 2 It can be seen that the manganese-based dual single-atom carbon catalyst created in this invention can effectively catalyze DOM in ozone mineralization water.

[0157] Figure 3 This diagram illustrates the formation of various DBPs before and after ozone oxidation treatment of actual surface water. From... Figure 3 It can be seen that the traditional ozone oxidation process can control a small amount of carbon-containing disinfection byproducts (C-DBPs), but at the same time it will generate a large amount of highly toxic nitrogen-containing disinfection byproducts (N-DBPs).

[0158] Figure 4 This diagram illustrates the formation of various DBPs before and after catalytic ozone oxidation treatment of actual surface water. From... Figure 4 It can be seen that the manganese dual single-atom carbon-based catalyst catalytic ozone oxidation system created in this invention can not only significantly control the generation of C-DBPs, but also significantly control the generation of N-DBPs, and the generation of highly toxic trichloronitromethane (TCNM), which has attracted widespread attention, is below the detection limit.

[0159] It should be noted that the method of the present invention can be applied to the advanced treatment of drinking water, replacing the ozone-biological activated carbon process in the advanced treatment of drinking water with a manganese dual single-atom carbon-based catalyst catalytic ozone oxidation process, thereby achieving effective removal of disinfection byproduct precursors and ensuring water supply safety.

[0160] It should also be noted that the method of the present invention can also be applied to large-scale scenarios such as high-end residential communities, large shopping malls, airports, railway stations, and ecological parks to prepare high-quality drinking water. The active oxygen species generated by the manganese double single-atom carbon-based catalyst can easily degrade high-risk pollutants in the water, effectively remove toxic byproduct precursors, and also have sterilization functions to ensure drinking water safety.

[0161] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for controlling disinfection byproducts in drinking water by ozone catalytic oxidation, characterized in that, Includes the following steps: The manganese dual single-atom carbon-based catalyst and the water to be treated were mixed and then ozone gas was introduced to carry out the reaction. The reaction time for introducing ozone gas is 5 min to 30 min, the ozone flow rate for introducing ozone gas for the reaction is 100 mL / min to 300 mL / min, and the dosage of the manganese dual single-atom carbon-based catalyst is 0.05 g / L to 0.25 g / L. The manganese-based dual single-atom carbon-based catalyst was prepared by the following method: S1: Add divalent zinc source and trivalent manganese source to dimethylformamide solution and mix to obtain solution A; S2: Dimethylimidazole is added to a dimethylformamide solution and mixed to obtain solution B; S3: Mix and react the solutions A and B to obtain manganese-doped ZIF-8 nanocrystals; S4: The manganese-doped ZIF-8 nanocrystals are subjected to a first high-temperature heat treatment under a protective atmosphere. The temperature of the first high-temperature heat treatment is 1000℃~1200℃ to obtain Mn and N co-doped nano-carbon. S5: The Mn and N co-doped nano-carbon is acid-treated for 3h~6h, thoroughly dried, and then subjected to a second high-temperature heat treatment under a protective atmosphere. The temperature of the second high-temperature heat treatment is 900℃~1100℃ to obtain a manganese single-atom carbon-based catalyst. S6: Add the manganese single-atom carbon-based catalyst, manganese source and nitrogen source into a solvent and stir ultrasonically to collect solid particles; S7: The solid particles are subjected to a third high-temperature heat treatment under a protective atmosphere. The temperature of the third high-temperature heat treatment is 1000℃~1200℃ to obtain the manganese double single-atom carbon-based catalyst. In the aforementioned manganese dual single-atom carbon-based catalyst, the loading of Mn single atoms is 0~2 at%, and the specific surface area is 1000 m². 2 / g~1200m 2 / g, the coordination number of Mn and N atoms is 0~4.

2. The method according to claim 1, characterized in that, In step S3, the mixing reaction time is 24h~48h; and / or, the mixing reaction temperature is 25℃~120℃.

3. The method according to claim 1, characterized in that, In step S4, the duration of the first high-temperature heat treatment is 0.5h to 1.5h; and / or, the heating rate of the first high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

4. The method according to claim 1, characterized in that, In step S5, the acid treatment time is 3h~6h. After the acid treatment, before the second high-temperature heat treatment, the product is dried.

5. The method according to claim 1, characterized in that, In step S5, the duration of the second high-temperature heat treatment is 3h to 3.5h; and / or, the heating rate of the second high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

6. The method according to claim 1, characterized in that, In step S7, the duration of the third high-temperature heat treatment is 0.5h to 1.5h; and / or, the heating rate of the third high-temperature heat treatment is 2.5℃ / min to 5.0℃ / min.

Images