Preparation method and application of surface hydroxylated monatomic catalyst with co-o-zn structure

Abstract

The present application belongs to the technical field of antibiotic degradation, and more particularly relates to a preparation method of a surface hydroxylated monatomic catalyst with a Co-O-Zn structure and application thereof. The surface hydroxylated monatomic catalyst with the Co-O-Zn structure is prepared by mixing zinc acetate and cobalt acetate as metal sources, dimethyl imidazole as a ligand, and reaction in a solvent, and then centrifuging, washing, drying and calcining. The catalyst has an asymmetric Co-O-Zn configuration and a large number of hydroxyl groups on the surface. The asymmetric coordination structure of Co-O-Zn can optimize the adsorption behavior of the oxidant, effectively adjust the interaction and electronic structure of the metal sites in the catalytic process, significantly enhance the catalytic reaction, and has strong resistance to external inorganic ions and organic matter interference.

Description

Technical Field

[0001] This invention belongs to the field of antibiotic degradation technology, and more specifically relates to a method for preparing a surface hydroxylated single-atom catalyst with a Co-O-Zn structure and its application. Background Technology

[0002] Single-atom catalysts (SACs) have attracted widespread attention in water treatment due to their high metal atom utilization, high catalytic activity, and tunable electronic structure. However, in real wastewater environments (especially acidic environments), the unsaturated coordination environment of the active metal centers makes them less stable than other heterogeneous catalysts. This instability often leads to the leaching and diffusion of metal centers into the water, which reduces catalytic performance and poses a risk of secondary pollution. Furthermore, current SAC research often requires complex and demanding synthetic techniques to achieve selective control of active species in oxidant systems, and studies on the activation of multiple oxidants and the targeted control of active species by a single SAC are rare. This limits the applicability of SACs in different oxidant systems. Therefore, designing a multifunctional SAC that can effectively activate multiple oxidants and selectively generate active species has become a pressing challenge for those skilled in the art. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing a surface-hydroxylated single-atom catalyst with a Co-O-Zn structure and its application, so as to solve the problems existing in the prior art.

[0004] To achieve the above objectives, the present invention provides the following solution:

[0005] One of the technical solutions of this invention is to provide a method for preparing a surface-hydroxylated single-atom catalyst with a Co-O-Zn structure, the steps of which include:

[0006] Using zinc acetate and cobalt acetate as metal sources and dimethylimidazole as a ligand, the mixture was reacted in a solvent, and after centrifugation, washing, drying, and calcination, the surface hydroxylated single-atom catalyst with the Co-O-Zn structure was obtained.

[0007] Furthermore, the mass ratio of zinc acetate to cobalt acetate is 1-2:0.05-0.1.

[0008] Furthermore, the mass ratio of zinc acetate to dimethylimidazole is 1-2:4-5.

[0009] Furthermore, the mixing reaction in the solvent is a mixing reaction in methanol, and the reaction time is 20-24 hours.

[0010] Furthermore, the solvent used for the centrifugal washing is methanol.

[0011] Furthermore, the drying temperature is 60-80℃, and the time is 10-12 hours.

[0012] Optionally, the drying method is vacuum drying.

[0013] Furthermore, the calcination temperature is 400-500℃, the heating rate is 2-5℃ / min, and the holding time is 1-2h.

[0014] Furthermore, the preparation steps of the surface hydroxylation single-atom catalyst with the Co-O-Zn structure include:

[0015] S1. Dissolve 1-2g of anhydrous zinc acetate and 0.05-0.1g of cobalt acetate tetrahydrate in 40-50mL of methanol and stir continuously for 5-10min to obtain solution A;

[0016] S2. Dissolve 4-5g of dimethylimidazole in 40-50mL of methanol and stir continuously for 5-10min to obtain solution B;

[0017] S3. Pour the solution B into the solution A and stir the reaction for 20-24 hours to obtain a viscous precursor solution;

[0018] S4. The viscous precursor solution is washed three times by centrifugation with methanol and then vacuum dried at 60-80℃ for 10-12h to obtain the precursor material.

[0019] S5. The precursor material is heated to 400-500℃ at a heating rate of 2-5℃ / min and held at that temperature for 1-2 hours to obtain the surface hydroxylated single-atom catalyst with the Co-O-Zn structure.

[0020] The surface-hydroxylated single-atom catalyst with a Co-O-Zn structure prepared in this invention possesses an asymmetric Co-O-Zn configuration and a large number of hydroxyl groups on its surface. The asymmetric coordination structure of Co-O-Zn can effectively regulate the interaction and electronic structure of metal sites during catalysis, significantly enhancing the catalytic reaction. The hydroxyl groups on the catalyst surface can effectively regulate the adsorption configuration of persulfate and peracetic acid, thereby selectively generating specific active species. The formation of hydroxyl groups on the catalyst surface is due to surface oxidation, water adsorption, or interaction with water or oxygen during the reaction. The ZnO component in this catalyst can also self-stabilize the pH of the reaction system, maintaining a neutral microenvironment and increasing the stability of the reaction system. This effectively solves the selective regulation problem encountered in the activation of multiple oxidants by single-atom catalysts, providing valuable insights for constructing SACs with multifunctional applications.

[0021] The second technical solution of the present invention provides a surface hydroxylation single-atom catalyst with a Co-O-Zn structure, wherein the surface hydroxylation single-atom catalyst with a Co-O-Zn structure is prepared by the above preparation method.

[0022] The third technical solution of the present invention provides an application of the above-mentioned surface hydroxylated single-atom catalyst with Co-O-Zn structure in the degradation of sulfamethoxazole.

[0023] Fourth technical solution of the present invention: A method for degrading sulfamethoxazole, comprising the following steps:

[0024] The above-mentioned surface hydroxylated single-atom catalyst with Co-O-Zn structure was added to the solution of sulfamethoxazole, stirred, and after reaching the adsorption-desorption equilibrium state, an oxidant was added to carry out the degradation reaction of sulfamethoxazole.

[0025] The oxidizing agent includes persulfate or peracetic acid.

[0026] The surface hydroxylated single-atom catalyst with a Co-O-Zn structure prepared in this invention is used to activate persulfate or peracetic acid to form a Fenton-like system for the degradation of sulfamethoxazole.

[0027] The present invention discloses the following technical effects:

[0028] In this invention, zinc acetate and cobalt acetate are used as metal precursors to synthesize a surface hydroxylation single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure. The Co-O-Zn configuration and surface hydroxylation structure design can efficiently activate persulfate and peracetic acid to directionally generate active species that degrade sulfamethoxazole.

[0029] The surface hydroxylation single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure prepared in this invention has the function of self-regulating the pH of the reaction system. This function is due to the fact that ZnO is an amphoteric metal oxide, which can react with both hydrogen ions and hydroxide ions. This function can maintain a neutral microenvironment in the reaction system. No matter how the initial pH of the system changes within the range of 3 to 8, the pH of the system can be maintained at around 6 after the reaction. This characteristic is beneficial to maintaining the stability of the catalytic system.

[0030] The surface hydroxylation single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure prepared by this invention can efficiently activate persulfate and peracetic acid in a short time, and can selectively generate sulfate radicals and singlet oxygen, respectively, to efficiently degrade sulfamethoxazole, and has a strong ability to resist interference from external inorganic ions and organic matter. Attached Figure Description

[0031] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0032] Figure 1 Characterization diagrams of CoSAs-ZnO in Example 1 and ZnO in Comparative Example 1 are shown, where a is the X-ray diffraction pattern, b is the Fourier transform infrared spectrum, and c is the synchrotron radiation absorption spectrum of CoSAs-ZnO.

[0033] Figure 2 This is a spherical aberration electron microscope image of CoSAs-ZnO.

[0034] Figure 3 The graphs show the performance of sulfamethoxazole degradation under the conditions of Experiment Examples 1-5, where a represents Experiment Examples 1-3 and b represents Experiment Examples 4-5.

[0035] Figure 4 The graphs show the performance of sulfamethoxazole degradation under the conditions of Experiments 6-9, where a is the SMX removal rate of Experiment 6, b is the SMX degradation curve of Experiment 8, c is the SMX removal rate of Experiment 7, and d is the SMX degradation curve of Experiment 9.

[0036] Figure 5 The pH changes during the degradation of sulfamethoxazole under the conditions of Experiment 10-11.

[0037] Figure 6 The removal rate of sulfamethoxazole in the cyclic degradation in Experiment Examples 12-13 is shown.

[0038] Figure 7 In Figure a, the ESR spectrum of sulfate radicals in the CoSAs-ZnO / PMS system is shown, and in Figure b, the ESR spectrum of singlet oxygen in the CoSAs-ZnO / PAA system is shown. Detailed Implementation

[0039] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0040] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0041] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0042] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0043] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0044] Example 1

[0045] The preparation steps of surface hydroxylation single-atom catalysts with Co-O-Zn structures (CoSAs-ZnO) include:

[0046] S1. Dissolve 2g of anhydrous zinc acetate and 0.1g of cobalt acetate tetrahydrate in 48mL of methanol and stir continuously for 10min to obtain solution A;

[0047] S2. Dissolve 4.44 g of dimethylimidazole in 48 mL of methanol and stir continuously for 10 min to obtain solution B;

[0048] S3. Pour solution B from step S2 into solution A from step S1, and stir the reaction for 24 hours to obtain a viscous precursor solution.

[0049] S4. The viscous precursor solution was washed three times by centrifugation with methanol and then vacuum dried at 60°C for 12 hours to obtain the precursor material.

[0050] S5. The precursor material is placed in a ceramic boat and sintered in a muffle furnace. The temperature is increased to 500°C at a heating rate of 2°C / min and held for 2 hours. After sintering, a surface hydroxylated single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure is obtained.

[0051] Example 2

[0052] The preparation steps of surface hydroxylation single-atom catalysts with Co-O-Zn structures (CoSAs-ZnO) include:

[0053] S1. Dissolve 1g of anhydrous zinc acetate and 0.05g of cobalt acetate tetrahydrate in 48mL of methanol and stir continuously for 10min to obtain solution A;

[0054] S2. Dissolve 4.44 g of dimethylimidazole in 48 mL of methanol and stir continuously for 10 min to obtain solution B;

[0055] S3. Pour solution B from step S2 into solution A from step S1, and stir the reaction for 24 hours to obtain a viscous precursor solution.

[0056] S4. The viscous precursor solution was washed three times by centrifugation with methanol and then vacuum dried at 60°C for 12 hours to obtain the precursor material.

[0057] S5. The precursor material is placed in a ceramic boat and sintered in a muffle furnace. The temperature is increased to 500°C at a heating rate of 2°C / min and held for 2 hours. After sintering, a surface hydroxylated single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure is obtained.

[0058] Example 3

[0059] The preparation steps of surface hydroxylation single-atom catalysts with Co-O-Zn structures (CoSAs-ZnO) include:

[0060] S1. Dissolve 1.5g of anhydrous zinc acetate and 0.075g of cobalt acetate tetrahydrate in 48mL of methanol and stir continuously for 10min to obtain solution A;

[0061] S2. Dissolve 4.44 g of dimethylimidazole in 48 mL of methanol and stir continuously for 10 min to obtain solution B;

[0062] S3. Pour solution B from step S2 into solution A from step S1, and stir the reaction for 24 hours to obtain a viscous precursor solution.

[0063] S4. The viscous precursor solution was washed three times by centrifugation with methanol and then vacuum dried at 60°C for 12 hours to obtain the precursor material.

[0064] S5. The precursor material is placed in a ceramic boat and sintered in a muffle furnace. The temperature is increased to 500°C at a heating rate of 2°C / min and held for 2 hours. After sintering, a surface hydroxylated single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure is obtained.

[0065] Comparative Example 1

[0066] The preparation steps of zinc oxide catalyst include:

[0067] S1. Dissolve 2g of anhydrous zinc acetate in 48mL of methanol and stir continuously for 10min to obtain solution A;

[0068] S2. Dissolve 4.44 g of dimethylimidazole in 48 mL of methanol and stir continuously for 10 min to obtain solution B;

[0069] S3. Pour solution B from step S2 into solution A from step S1, and stir the reaction for 24 hours to obtain a viscous precursor solution.

[0070] S4. The viscous precursor solution was washed three times by centrifugation with methanol and then vacuum dried at 60°C for 12 hours to obtain the precursor material.

[0071] S5. The precursor material is placed in a ceramic boat and sintered in a muffle furnace. The temperature is increased to 500°C at a heating rate of 2°C / min and held for 2 hours. After sintering, zinc oxide catalyst (ZnO) is obtained.

[0072] Figure 1 Characterization diagrams of CoSAs-ZnO from Example 1 and ZnO from Comparative Example 1 are shown. In diagram a, X-ray diffraction pattern; in diagram b, Fourier transform infrared spectrum; and in diagram c, synchrotron radiation absorption spectrum of CoSAs-ZnO. As shown in the diagrams, in diagram a, the introduction of cobalt did not disrupt the phase structure of zinc oxide, and no other cobalt-related diffraction peaks appeared, indicating the successful synthesis of a cobalt single-atom catalyst. In diagram b, hydroxyl groups are present on the surface of the CoSAs-ZnO catalyst. In diagram c, compared to the Co-Co bonds in Co foil and the Co-O bonds in CoO, the Co in the CoSAs-ZnO catalyst only exhibits Co-O and Co-O-Zn bonds, demonstrating that the Co in this catalyst exhibits a single-atom distribution and possesses an asymmetric Co-O-Zn configuration. These results demonstrate the successful synthesis of a surface-hydroxylated single-atom catalyst (CoSAs-ZnO) with a Co-O-Zn structure.

[0073] Figure 2 The image shows a spherical aberration electron microscope image of CoSAs-ZnO. As can be seen from the image, there are many isolated bright spots, which are Co single atoms. This proves that Co exists in single-atom form without the formation of clusters and nanoparticles.

[0074] Effect test

[0075] The catalysts prepared in Examples 1-3 of this invention showed similar effects when used for the degradation of sulfamethoxazole (SMX). Therefore, the catalyst prepared in Example 1 was used in the following experiments to conduct the degradation test of sulfamethoxazole (SMX).

[0076] Experimental Example 1

[0077] The catalysts prepared in Example 1 and Comparative Example 1 were used to activate persulfate (PMS) for the degradation of sulfamethoxazole (SMX). The specific steps of the method are as follows:

[0078] Weigh 5 mg of catalyst using an analytical balance and add it to 50 mL of 10 mg / L SMX solution. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 94 μL of 80 mM persulfate solution (PMS) and start timing the reaction.

[0079] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0080] Experimental Example 2

[0081] The catalysts prepared in Example 1 and Comparative Example 1 were used alone to degrade sulfamethoxazole (SMX). The specific steps of the method are as follows:

[0082] Weigh 5 mg of catalyst using an analytical balance and add it to 50 mL of SMX solution with a concentration of 10 mg / L. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium, and then start timing the reaction.

[0083] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0084] Experimental Example 3

[0085] The specific steps of the method for degrading sulfamethoxazole (SMX) using persulfate monophosphate (PMS) are as follows:

[0086] Take 50 mL of 10 mg / L SMX solution, stir magnetically for 5 min, then add 94 μL of 80 mM persulfate solution (PMS), and start timing the reaction.

[0087] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0088] Test Example 4

[0089] The catalysts prepared in Example 1 and Comparative Example 1 were used to activate peracetic acid (PAA) to degrade sulfamethoxazole (SMX). The specific steps of the method are as follows:

[0090] Weigh 5 mg of catalyst using an analytical balance and add it to 50 mL of 10 mg / L SMX solution. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 15 μL of 80 mM peracetic acid solution (PAA) and start timing the reaction.

[0091] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0092] Experimental Example 5

[0093] The specific steps of the method for degrading sulfamethoxazole (SMX) using peracetic acid (PAA) alone are as follows:

[0094] Take 50 mL of SMX solution with a concentration of 10 mg / L, stir magnetically for 5 min, then add 15 μL of peracetic acid (PAA) with a concentration of 80 mM, and start timing the reaction.

[0095] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0096] Figure 3The graphs show the performance of sulfamethoxazole degradation under the conditions of Experiments 1-5, where a represents Experiments 1-3 and b represents Experiments 4-5. As shown in the graphs, in a, sulfamethoxazole was almost completely removed in the presence of PMS alone, indicating that PMS alone cannot oxidize and degrade sulfamethoxazole. Furthermore, sulfamethoxazole was also almost completely removed in the presence of both ZnO and CoSAs-ZnO catalysts, indicating that their adsorption contributions were negligible. The ZnO catalyst achieved a 7.5% degradation rate of sulfamethoxazole by activating PMS within 6 minutes, while the CoSAs-ZnO catalyst achieved a 99.8% degradation rate by activating PMS within 6 minutes. In b, sulfamethoxazole was hardly removed in the presence of PAA alone, indicating that PAA alone cannot oxidize and degrade sulfamethoxazole. The ZnO catalyst can achieve a 7.3% degradation rate of sulfamethoxazole by activating PAA within 6 min, while the CoSAs-ZnO catalyst can achieve a 98.3% efficiency in degrading sulfamethoxazole by activating PAA within 6 min.

[0097] Experimental Example 6

[0098] Under conditions where inorganic ions are present at different concentrations, the catalyst (CoSAs-ZnO) prepared in Example 1 was used to activate the degradation of sulfamethoxazole (SMX) by persulfate (PMS). The specific steps of the method are as follows:

[0099] The inorganic ions are chloride ions, nitrate ions, and sulfate ions, and the corresponding drugs are sodium chloride, sodium nitrate, and sodium sulfate, respectively, with dosage concentrations of 1 mM, 2 mM, and 5 mM. Specifically, the dosage masses of chloride ions (sodium chloride) are 2.9 mg, 5.8 mg, and 14.6 mg, respectively; the dosage masses of nitrate ions (sodium nitrate) are 4.25 mg, 8.5 mg, and 21.2 mg, respectively; and the dosage masses of sulfate ions (sodium sulfate) are 7.1 mg, 14.2 mg, and 35.5 mg, respectively.

[0100] Weigh out the inorganic salt corresponding to the inorganic ion of the appropriate concentration and add it to 50 mL of SMX solution with a concentration of 10 mg / L. Then add 5 mg of CoSAs-ZnO catalyst and stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 94 μL of persulfate solution with a concentration of 80 mM (PMS) and start timing the reaction.

[0101] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0102] Experimental Example 7

[0103] Under conditions where inorganic ions are present at different concentrations, the catalyst (CoSAs-ZnO) prepared in Example 1 was used to activate the degradation of sulfamethoxazole (SMX) by peracetic acid (PAA). The specific steps of the method are as follows:

[0104] The inorganic ions are chloride ions, nitrate ions, and sulfate ions, and the corresponding drugs are sodium chloride, sodium nitrate, and sodium sulfate, respectively, with dosage concentrations of 1 mM, 2 mM, and 5 mM. Specifically, the dosage masses of chloride ions (sodium chloride) are 2.9 mg, 5.8 mg, and 14.6 mg, respectively; the dosage masses of nitrate ions (sodium nitrate) are 4.25 mg, 8.5 mg, and 21.2 mg, respectively; and the dosage masses of sulfate ions (sodium sulfate) are 7.1 mg, 14.2 mg, and 35.5 mg, respectively.

[0105] Weigh out the inorganic salt corresponding to the inorganic ion of the appropriate concentration and add it to 50 mL of SMX solution with a concentration of 10 mg / L. Then add 5 mg of CoSAs-ZnO catalyst and stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 15 μL of peracetic acid (PAA) with a concentration of 80 mM and start timing the reaction.

[0106] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0107] Experimental Example 8

[0108] Under conditions where different concentrations of organic matter (humic acid) are present, the catalyst (CoSAs-ZnO) prepared in Example 1 was used to activate the degradation of sulfamethoxazole (SMX) by persulfate (PMS). The specific steps of the method are as follows:

[0109] The organic matter was humic acid, and the experimental concentrations were 1 mg / L, 2 mg / L, and 5 mg / L.

[0110] Preparation of SMX solution (10 mg / L) containing humic acid (1 mg / L): Measure 49.75 mL of SMX solution (10 mg / L), and then add 0.25 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0111] Preparation of SMX solution (10 mg / L) containing humic acid (2 mg / L): Measure 49.5 mL of SMX solution (10 mg / L), and then add 0.5 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0112] Preparation of SMX solution (10 mg / L) containing humic acid (5 mg / L): Measure 48.75 mL of SMX solution (10 mg / L), and then add 1.25 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0113] Weigh 5 mg of CoSAs-ZnO catalyst and add it to the solution prepared above. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 94 μL of 80 mM persulfate solution (PMS) and start timing the reaction.

[0114] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0115] Experimental Example 9

[0116] Under conditions where different concentrations of organic matter (humic acid) are present, the catalyst (CoSAs-ZnO) prepared in Example 1 was used to activate the degradation of sulfamethoxazole (SMX) by peracetic acid (PAA). The specific steps of the method are as follows:

[0117] The organic matter was humic acid, and the experimental concentrations were 1 mg / L, 2 mg / L, and 5 mg / L.

[0118] Preparation of SMX solution (10 mg / L) containing humic acid (1 mg / L): Measure 49.75 mL of SMX solution (10 mg / L), and then add 0.25 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0119] Preparation of SMX solution (10 mg / L) containing humic acid (2 mg / L): Measure 49.5 mL of SMX solution (10 mg / L), and then add 0.5 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0120] Preparation of SMX solution (10 mg / L) containing humic acid (5 mg / L): Measure 48.75 mL of SMX solution (10 mg / L), and then add 1.25 mL of 200 mg / L humic acid solution to it, keeping the total solution volume at 50 mL.

[0121] Weigh 5 mg of CoSAs-ZnO catalyst and add it to the solution prepared above. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 15 μL of 80 mM peracetic acid (PAA) and start timing the reaction.

[0122] Take 1 mL of sample every 1 min for a total of 6 min. After taking the sample, add it to a test tube containing sodium thiosulfate solution and shake well to terminate the reaction. After terminating the reaction, centrifuge at 14000 rpm for 20 min. Take the supernatant and inject it into a high performance liquid chromatograph to detect the residual SMX concentration to determine the removal efficiency.

[0123] Figure 4 The graphs show the performance of sulfamethoxazole degradation under the conditions of Experiments 6-9, where a represents the SMX removal rate of Experiment 6, b represents the SMX degradation curve of Experiment 8, c represents the SMX removal rate of Experiment 7, and d represents the SMX degradation curve of Experiment 9. Figure 4 It can be seen that the presence of complex anions and natural organic macromolecules did not interfere with the degradation and removal of sulfamethoxazole by the CoSAs-ZnO / PMS system and the CoSAs-ZnO / PAA system, indicating that the CoSAs-ZnO / PMS system and the CoSAs-ZnO / PAA system are suitable for the purification of complex water bodies.

[0124] Experimental Example 10

[0125] The method for measuring the pH change of solution during the activation of persulfate (PMS) to degrade sulfamethoxazole (SMX) using the catalyst (CoSAs-ZnO) prepared in Example 1 is as follows:

[0126] 5 mg of CoSAs-ZnO catalyst was added to SMX solutions with pH values ​​of 3.0, 5.0, 7.0, and 8.0, respectively. The pH meter probe was submerged in the solution, and the mixture was stirred with a magnetic stirrer for 5 min, during which the pH values ​​were recorded. Then, 94 μL of 80 mM persulfate solution (PMS) was added, and a value was recorded every 1 min for a total reaction time of 6 min.

[0127] Experimental Example 11

[0128] The method for measuring the pH change of solution during the activation of peracetic acid (PAA) to degrade sulfamethoxazole (SMX) using the catalyst (CoSAs-ZnO) prepared in Example 1 is as follows:

[0129] 5 mg of CoSAs-ZnO catalyst was added to SMX solutions with pH values ​​of 3.0, 5.0, 7.0, and 8.0, respectively. The pH meter probe was submerged in the solution, and the mixture was stirred with a magnetic stirrer for 5 min, during which the pH count was recorded. Then, 15 μL of 80 mM peracetic acid (PAA) was added, and a value was recorded every 1 min for a total reaction time of 6 min.

[0130] Figure 5 The figure shows the pH changes during the degradation of sulfamethoxazole under the conditions of Experiment 10-11. As can be seen from the figure, no matter how the initial pH of the sulfamethoxazole solution changes within the range of 3 to 8, the CoSAs-ZnO catalyst can stabilize the pH of the system solution at around 6. This indicates that CoSAs-ZnO has the function of regulating the pH of the solution and can maintain the neutral microenvironment of the system.

[0131] Experimental Example 12

[0132] The catalyst prepared in Example 1 was used to activate the persulfate (PMS) cycle for the degradation of sulfamethoxazole (SMX). The specific steps of the method are as follows:

[0133] Weigh 10 mg of catalyst using an analytical balance and add it to 50 mL of 10 mg / L SMX solution. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 625 μL of 80 mM persulfate solution (PMS) and start timing the reaction.

[0134] After 6 minutes of reaction, take a 1 mL sample and add it to a test tube containing sodium thiosulfate solution. Shake well to terminate the reaction. After 6 minutes, SMX has been completely degraded. Then, add 200 mg / L SMX solution to the solution after the above reaction to maintain the SMX concentration at 10 mg / L. Then, add 625 μL of 80 mM persulfate solution (PMS) and continue timing the reaction (6 minutes). After the reaction is completed, take a 1 mL sample and add it to a test tube containing sodium thiosulfate solution. Shake well to terminate the reaction. Repeat the above operation five times, for a total of five cycles.

[0135] Finally, the sample after five cycles was placed in a centrifuge and centrifuged at 14,000 rpm for 20 minutes. The supernatant was then injected into a high-performance liquid chromatograph to detect the residual SMX concentration and determine the removal efficiency.

[0136] Experimental Example 13

[0137] The catalyst prepared in Example 1 was used to activate the cyclic degradation of sulfamethoxazole (SMX) by peracetic acid (PAA). The specific steps of the method are as follows:

[0138] Weigh 20 mg of catalyst using an analytical balance and add it to 50 mL of SMX solution with a concentration of 10 mg / L. Stir magnetically for 5 min to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. Then add 625 μL of peracetic acid (PAA) with a concentration of 80 mM and start timing the reaction.

[0139] After 6 minutes of reaction, take a 1 mL sample and add it to a test tube containing sodium thiosulfate solution. Shake well to terminate the reaction. After 6 minutes, SMX has been completely degraded. Then, add 200 mg / L SMX solution to the solution after the above reaction to maintain the SMX concentration at 10 mg / L. Then, add 625 μL of 80 mM peracetic acid (PAA) and continue timing the reaction (6 minutes). After the reaction is completed, take a 1 mL sample and add it to a test tube containing sodium thiosulfate solution. Shake well to terminate the reaction. Repeat the above operation five times, for a total of five cycles.

[0140] Finally, the sample after five cycles was placed in a centrifuge and centrifuged at 14,000 rpm for 20 minutes. The supernatant was then injected into a high-performance liquid chromatograph to detect the residual SMX concentration and determine the removal efficiency.

[0141] Figure 6 The figure shows the removal rate of sulfamethoxazole in the cyclic degradation of Experimental Examples 12-13. As can be seen from the figure, both systems have good cyclic stability and can still achieve a degradation efficiency of nearly 97% after five cycles. This indicates that the CoSAs-ZnO catalyst prepared in this invention has good structural stability.

[0142] Test Example 14

[0143] The detection steps for sulfate radicals in the persulfate (PMS) system of the catalyst prepared in Example 1 are as follows:

[0144] 2 mg of CoSAs-ZnO was dispersed in 5 mL of DMPO aqueous solution (concentration 100 mM). The mixture was placed into a quartz capillary tube with an inner diameter of 0.9 mm, and the bottom was sealed with a wax seal. The capillary tube was inserted into the test chamber of the EPR, and the first data was recorded. 50 μL of persulfate solution (80 mM) was added to the CoSAs-ZnO dispersion, and data were collected after 1 min and 3 min of reaction. Then, 100 μL of SMX solution was added to the system, and data was collected after 1 min of reaction.

[0145] Experimental Example 15

[0146] The detection steps for singlet oxygen in the peracetic acid (PAA) system using the catalyst prepared in Example 1 are as follows:

[0147] 2 mg of CoSAs-ZnO was dispersed in 5 mL of TEMP aqueous solution (concentration 100 mM). The mixture was placed into a quartz capillary tube with an inner diameter of 0.9 mm, and the bottom was sealed with a wax seal. The capillary tube was inserted into the test chamber of an EPR device, and the first data was recorded. 50 μL of peracetic acid solution (80 mM) was added to the CoSAs-ZnO dispersion, and data were collected after 1 min and 3 min of reaction. Then, 100 μL of SMX solution was added to the system, and data were collected after 1 min of reaction.

[0148] Figure 7 Figure a shows the ESR spectrum of sulfate radicals in the CoSAs-ZnO / PMS system, and figure b shows the ESR spectrum of singlet oxygen in the CoSAs-ZnO / PAA system. As can be seen from the figures, after the catalyst reacts with the oxidant, sulfate radicals and singlet oxygen exhibit strong spectral signals, and the signal intensity gradually increases with the extension of reaction time. This indicates that the CoSAs-ZnO catalyst can efficiently activate persulfate in a short time, selectively generating highly oxidizing sulfate radicals or singlet oxygen, thereby efficiently degrading various organic pollutants.

[0149] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0150] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a surface-hydroxylated single-atom catalyst with an asymmetric Co-O-Zn structure, characterized in that the step... include: Using zinc acetate and cobalt acetate as metal sources and dimethylimidazole as ligand, the mixture was reacted in a solvent, and after centrifugation, washing, drying, and calcination, the surface hydroxylated single-atom catalyst with an asymmetric Co-O-Zn structure was obtained. The calcination is carried out in a muffle furnace at a temperature of 400-500℃, a heating rate of 2-5℃ / min, and a holding time of 1-2h. The mass ratio of zinc acetate to cobalt acetate is 1-2:0.05-0.

1.

2. The preparation method according to claim 1, characterized in that, The mass ratio of zinc acetate to dimethylimidazole is 1-2:4-5.

3. The preparation method according to claim 1, characterized in that, The mixing reaction in the solvent is a mixing reaction in methanol, and the reaction time is 20-24 hours.

4. The preparation method according to claim 1, characterized in that, The solvent used for centrifugal washing is methanol.

5. The preparation method according to claim 1, characterized in that, The drying temperature is 60-80℃, and the time is 10-12 hours.

6. A surface-hydroxylated single-atom catalyst with an asymmetric Co-O-Zn structure, characterized in that, The surface hydroxylated single-atom catalyst with an asymmetric Co-O-Zn structure is prepared by the preparation method described in any one of claims 1-5.

7. The application of the surface hydroxylation single-atom catalyst with an asymmetric Co-O-Zn structure as described in claim 6 in the degradation of sulfamethoxazole.

8. A method for degrading sulfamethoxazole, characterized in that the step include: The surface hydroxylation single-atom catalyst with an asymmetric Co-O-Zn structure as described in claim 6 was added to a solution of sulfamethoxazole, stirred, and after reaching an adsorption-desorption equilibrium state, an oxidant was added to carry out the degradation reaction of sulfamethoxazole. The oxidizing agent includes persulfate or peracetic acid.

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