A single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst, a preparation method and application thereof

Abstract

The application discloses a single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst and a preparation method and application thereof, and belongs to the technical field of water pollution control. The preparation method comprises the following steps: dissolving 1-allyl-2-thiourea and a cobalt salt in water, adding SiO2 nanospheres into the solution, stirring under heating, and obtaining a precursor after evaporating the solvent; calcining the precursor under the protection of an inert gas, etching SiO2 after calcination, and drying after acid immersion and washing, so that the single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst is obtained. In the application, SiO2 is used as a substrate, and an asymmetric Co-S / Co-N coordination structure is introduced, so that the performance of traditional Co-SACs in activating peroxyacetic acid is significantly enhanced, and the infiltration of cobalt ions in the activation process is effectively inhibited, so that secondary pollution is not generated in the catalytic process, and the catalytic efficiency can be maintained to be very high after multiple recycling, and efficient, stable and continuous degradation of organic pollutants can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water pollution control, and particularly relates to a single-layer eggshell-shaped nitrogen-sulfur co-doped single-atom cobalt catalyst as well as a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in the background of the present application is only intended to increase the understanding of the overall background of the present application and should not necessarily be regarded as acknowledging or implying in any form that the information constitutes prior art known to those skilled in the art.

[0003] Antibiotics, as a typical emerging pollutant, have the characteristics of large amount and wide range of use, and are widely detected in natural water environment. Although the exposure level of antibiotics in the environment is low at present, due to their stable structure, biological accumulation effect and amplification effect, the potential harm to the ecological system cannot be ignored. In view of the complexity of the source and composition of antibiotics pollution in water bodies at present, sewage treatment needs to be targeted and sustainable to purify specific types of sewage, so as to achieve accurate oxidative degradation of trace antibiotics in different water environments, and therefore it is imperative to develop a selectively adjustable treatment technology.

[0004] Advanced oxidation technology (AOPs) relies on the in-situ generation of strong oxidizing active substances, which can efficiently degrade antibiotics and even completely mineralize them. Therefore, AOPs are widely used in the treatment of antibiotic pollution. In recent years, peracetic acid (PAA) advanced oxidation technology (PAA-AOPs) based on in-situ generation of organic free radicals (R-O·) has attracted more and more attention from researchers, and has shown great potential in water remediation due to its advantages such as simple operation, low cost and less toxic by-products. In addition, compared with inorganic free radical active substances (such as ·OH, SO4· - ) generated in traditional AOPs systems, R-O· has a longer survival time and is less affected by complex matrix in water, and therefore has stronger selective degradation ability for antibiotic emerging pollutants.

[0005] The construction of a new type of efficient catalyst system is the main research direction of PAA advanced oxidation technology at present, and the core lies in the development of heterogeneous catalysts with high activity and stability to improve the generation efficiency of active substances. Single-atom catalysts (SACs) are a new type of catalyst composed of isolated metal single atoms anchored on a suitable support. At present, the application of SACs in the activation of PAA is still in its infancy, and the reported single-atom cobalt catalysts (Co-SACs) are difficult to meet the actual requirements in terms of activation efficiency and catalyst stability. Therefore, it is necessary to further regulate Co-SACs to enhance their activity and stability, and to provide theoretical and technical support for the popularization and application of PAA advanced oxidation technology. SUMMARY

[0006] Therefore, the single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst, the preparation method and application thereof are provided.

[0007] In a first aspect, the application provides a preparation method of a single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst, comprising the following steps:

[0008] Dissolve 1-allyl-2-thiourea and a cobalt salt in water, add SiO2 nanospheres thereto, heat and stir, and obtain a precursor after evaporation of the solvent;

[0009] Perform calcination on the precursor under the protection of an inert gas, etch SiO2 after calcination, and then perform acid immersion, washing and drying to obtain the single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst.

[0010] In a second aspect, the application provides the single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst prepared by the above preparation method.

[0011] In a third aspect, the application provides application of the single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst in activation of peroxyacetic acid to degrade organic pollutants.

[0012] Compared with the prior art, the application has the following beneficial effects:

[0013] (1) The single-layer eggshell-like nitrogen and sulfur co-doped single-atom cobalt catalyst is prepared by taking SiO2 nanospheres as a base template, introducing an asymmetric Co-S / Co-N coordination structure through calcination with a cobalt salt and 1-allyl-2-thiourea; the introduction of the asymmetric coordination structure can cause significant delocalized electrons around the Co center, thereby promoting the adsorption of PAA and the cleavage of the O-O bond; the asymmetric electronic structure also produces an additional local electric field, which is conducive to the cleavage of the O-H bond in PAA through the proton-coupled electron transfer pathway; SiO2 not only plays a key role in the formation of the eggshell-like morphology of the catalyst, but also provides abundant coordination sites for single-atom cobalt; the thin shell structure of the single-layer eggshell is conducive to the maximum utilization of metal catalytic sites, promotes the contact of the Co-S / Co-N sites with PAA and pollutants, and the internal cavity can enhance the removal efficiency of pollutants through the confinement effect; at the same time, the preparation method of the application can obtain a high loading amount of single-atom cobalt, and the loading amount can reach about 10wt%.

[0014] (2) The single-layer eggshell-shaped nitrogen-sulfur co-doped single-atom cobalt catalyst of the present invention can catalyze the decomposition of peracetic acid to generate a variety of active oxygen species in situ, including ·OH, RO· and singlet oxygen ( 1 O2), achieving highly efficient degradation of multiple antibiotics in wastewater, with sulfamethoxazole degradation rates exceeding 95% achieved in less than 2 minutes. Furthermore, the catalyst produces no secondary pollution during the catalytic process and maintains extremely high catalytic efficiency after multiple recycling. The nitrogen-sulfur co-doped single-atom cobalt catalyst prepared using this invention can catalyze the activation of peracetic acid to degrade antibiotics in wastewater under a near-neutral environment. In actual treatment, the addition of acid or alkali to adjust the pH is unnecessary, reducing economic costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute undue limitations thereon. It is obvious that one of ordinary skill in the art could derive other drawings based on these drawings without inventive effort.

[0016] Figure 1 This is a scanning electron microscope (SEM) image of the nitrogen-sulfur co-doped single-atom cobalt catalyst prepared in Example 1 of the present invention;

[0017] Figure 2 This is an elemental scanning image of the nitrogen-sulfur co-doped single-atom cobalt catalyst prepared in Example 1 of the present invention under SEM mode;

[0018] Figure 3 This is a spherical aberration correction-high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) image of the nitrogen-sulfur co-doped single-atom cobalt catalyst prepared in Example 1 of the present invention;

[0019] Figure 4 This is a comparison of the effects of activating peracetic acid to degrade sulfamethoxazole using single-atom cobalt catalysts in Examples 1-2 and Comparative Examples 1-2;

[0020] Figure 5 This is a comparison of the effects of activating peracetic acid to degrade sulfamethoxazole using single-atom cobalt catalysts of Examples 1, 3, and 4 of the present invention;

[0021] Figure 6 Comparison of the effects of activating peracetic acid and degrading sulfamethoxazole using single-atom cobalt catalysts in Examples 1 and 5 of the present invention and Comparative Examples 3 to 4;

[0022] Figure 7 This is a comparison of the effects of activating peracetic acid to degrade sulfamethoxazole using single-atom cobalt catalysts of Examples 1, 6, and 7 of the present invention;

[0023] Figure 8 Figure for removal effect of sulfamethoxazole degraded by peracetic acid activated by monatomic cobalt catalyst prepared in example 1 of the present application under different pH conditions;

[0024] Figure 9 Figure for removal effect of sulfamethoxazole degraded by peracetic acid activated by monatomic cobalt catalyst prepared in example 1 of the present application under different pH conditions;

[0025] Figure 10 Figure for removal effect of sulfamethoxazole degraded by peracetic acid activated by monatomic cobalt catalyst prepared in example 1 of the present application under different pH conditions;

[0026] Figure 11 Figure for removal effect of sulfamethoxazole degraded by peracetic acid activated by monatomic cobalt catalyst prepared in example 1 of the present application under different pH conditions;

[0027] Figure 12 Figure for removal effect of sulfamethoxazole degraded by peracetic acid activated by monatomic cobalt catalyst prepared in example 1 of the present application under different pH conditions; DETAILED DESCRIPTION

[0028] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0029] The present application provides a preparation method of a single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst, comprising the following steps:

[0030] Dissolve 1-allyl-2-thiourea and cobalt salt in water, add SiO2 nanospheres thereto, heat and stir, and obtain a precursor after evaporation of the solvent;

[0031] Perform calcination on the precursor under inert gas protection, etch SiO2 after calcination, and then perform acid immersion, washing and drying to obtain the single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst.

[0032] In the present application, 1-allyl-2-thiourea is used as a sulfur source and a nitrogen source, and an asymmetric Co-S / Co-N coordination structure is introduced on the SiO2 substrate in the calcination process of the cobalt salt and the SiO2 nanospheres, and Co is distributed in the form of monatomic. Then, a single-layer eggshell-shaped thin shell morphology is formed by etching SiO2, which can maximize the utilization of metal catalytic sites, thereby promoting the contact between Co-S / Co-N sites and PAA and pollutants, and the internal cavity can enhance the removal efficiency of pollutants through the confinement effect. The loading amount of monatomic cobalt in the catalyst prepared by the above method of the present application can reach about 10wt%, which has a high monatomic cobalt loading amount.

[0033] In the present invention, the cobalt salt is selected from cobalt nitrate, cobalt chloride or cobalt sulfate. In practical applications, hydrated salts of the above cobalt salts can be selected, and the present invention does not impose any particular restrictions on this. The choice of cobalt salt will affect the catalytic effect to a certain extent, and cobalt nitrate is more preferably used in the present invention.

[0034] In the present invention, the molar ratio of the cobalt salt to 1-allyl-2-thiourea is 1:(15-35); the molar ratio of the two will also affect the final catalytic effect. Too much cobalt salt has an adverse effect on the dispersibility of the single atomic cobalt, and too little cobalt salt will result in too few metal active sites, both of which will reduce the catalytic activity. The ratio of the 1-allyl-2-thiourea to water is 1g:(3-10)mL. Water is used as a solvent to dissolve the cobalt salt and 1-allyl-2-thiourea and allow the two to mix thoroughly. It also serves as a dispersing solvent for SiO2, allowing it to mix thoroughly with the cobalt salt and 1-allyl-2-thiourea in the solution. The mass ratio of cobalt salt to SiO2 nanospheres is 0.08:(0.5-2), and more preferably 0.08:(0.8-1.2).

[0035] The present invention does not impose any special restrictions on the preparation method of SiO2 nanospheres. The present invention preferably adopts the Stober method for preparation. Those skilled in the art can obtain SiO2 nanospheres according to conventional means in the art. The particle size of the SiO2 nanospheres is 100 to 300 nm.

[0036] In the present invention, the heating and stirring temperature is 60-90° C., and the heating and stirring time is 60-180 min; the evaporation temperature of the solvent is 50-70° C., and the specific time required depends on the complete evaporation of the solvent, which is not particularly limited in the present invention.

[0037] In the present invention, the inert gas is selected from nitrogen or argon, more preferably argon.

[0038] In the present invention, the calcination temperature is 850-1000°C, more preferably 900-1000°C. Excessively high or low calcination temperatures may affect the activity of the prepared catalyst. The calcination time is 2-4 hours. The time to reach the calcination temperature is preferably 2-8°C / min.

[0039] In the present invention, the method for etching SiO2 is to use sodium hydroxide or potassium hydroxide solution for etching, which has a relatively low etching risk; the concentration of the sodium hydroxide or potassium hydroxide solution is 3 to 8 mol / L.

[0040] In the present application, the acid immersion process uses hydrochloric acid or sulfuric acid solution with a concentration of 0.05-0.5 mol / L. The acid immersion process can neutralize the alkali in the aforementioned etching process on the one hand, and can remove the residual metal cobalt on the surface of the catalyst (monatomic cobalt does not react with acid) on the other hand. The acid immersion time is 40-120 min, and after the acid immersion is completed, water and ethanol are used for washing, and then drying is performed. The present application does not have special restrictions on the drying process, and the present application preferably is vacuum drying at 50-80 DEG C.

[0041] The present application also provides a single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst prepared by the above preparation method, wherein the loading amount of monatomic cobalt is about 10 wt%.

[0042] The present application also provides the application of the above single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst in activating peroxiacetic acid to degrade antibiotics. In the single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst provided by the present application, the introduction of the Co-S / Co-N asymmetric coordination structure can cause significant delocalized electrons around the Co center, thereby promoting the adsorption of PAA and the cleavage of the O-O bond. The asymmetric electronic structure also produces an additional local electric field, which is conducive to the cleavage of the O-H bond in PAA through the proton-coupled electron transfer pathway. The single-layer eggshell-shaped thin shell structure promotes the contact of the Co-S / Co-N sites with PAA and pollutants, and the internal cavity can enhance the removal efficiency of pollutants through the confinement effect. The catalyst can catalyze peroxiacetic acid to generate various active oxygen species in situ, including ·OH, R-O· and singlet oxygen (O2), and can achieve efficient degradation of various antibiotics in wastewater, including sulfamethoxazole (SMX), sulfadiazine (SDZ), sulfisomidine (SDM), sulfamethizole (SMIZ), ciprofloxacin (CIP), enrofloxacin (ENF), tetracycline (TTC), 4-chlorophenol (4-CP) and phenol (PN) and the like. 1 O2), can achieve efficient degradation of various antibiotics in wastewater, including sulfamethoxazole (SMX), sulfadiazine (SDZ), sulfisomidine (SDM), sulfamethizole (SMIZ), ciprofloxacin (CIP), enrofloxacin (ENF), tetracycline (TTC), 4-chlorophenol (4-CP) and phenol (PN) and the like.

[0043] In the present application, the ratio of the single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst, peroxiacetic acid and organic pollutants is (50-150) mg:(0.2-0.6) mmol:(1-15) μmol; the concentration of the single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst is 50-150 mg / L. The pH of the application process is 5-8, more preferably 6-7.

[0044] The technical solutions of the present application will be further described below in combination with specific examples. The present application does not have special restrictions on the sources of reagents used in the following examples, and commercially available goods known to those skilled in the art can be used. The room temperature or normal temperature in the following examples is 25±3 DEG C.

[0045] In the following examples, the SiO2nanospheres were prepared as follows: 6 mL of tetraethyl orthosilicate (TEOS) was added to 210 mL of absolute ethanol and stirred continuously. Then 7.2 mL of ammonium hydroxide (25 wt%) and 42 mL of deionized water were added dropwise to the above solution. The mixed solution was stirred at room temperature for 24 h to form a white suspension. The solid precipitate was then separated by centrifugation at 8500 rpm for 5 min and washed with deionized water and ethanol for 3 times. Finally, the SiO2nanospheres were obtained by drying in a vacuum oven at 65 °C for 12 h with an average particle size of 200 nm.

[0046] Example 1

[0047] The present example provides a preparation method of a nitrogen-sulfur co-doped single-atom cobalt catalyst.

[0048] (1) 1.0 g of 1-allyl-2-thiourea (8.62 mmol) and 80 mg of Co(NO3)2·6H2O (0.27 mmol, i.e., the molar ratio of 1-allyl-2-thiourea to Co(NO3)2·6H2O is 32:1) were added to 5 mL of deionized water and stirred to form a clear solution, then 1.0 g of SiO2nanospheres was added, and the mixture was stirred in a beaker at 80 °C for 2 h, and the precursor was obtained by slowly evaporating the solvent in an oven at 60 °C.

[0049] (2) The precursor of step (1) was heated to 900 °C at a heating rate of 5 °C / min under an argon atmosphere and calcined for 3 h to obtain a calcined product.

[0050] (3) After the calcined product was naturally cooled to room temperature, the SiO2nanosphere template was removed using a 5 mol / L NaOH solution, and acid immersion was performed in 0.1 M hydrochloric acid for 60 min to remove residual metals, then washed with deionized water and ethanol for 3 times each, and dried in a vacuum oven at 65 °C for 12 h to obtain a nitrogen-sulfur co-doped single-atom cobalt catalyst (denoted as Co-CNS). SA

[0051] Figure 1 The scanning electron microscope (SEM) image of the nitrogen-sulfur co-doped single-atom cobalt catalyst prepared in the present example; it can be seen from Figure 1 that the prepared single-atom cobalt catalyst exhibits a typical monolayer thin shell spherical structure.

[0052] Figure 2 The elemental scanning (EDX) characterization image of the nitrogen-sulfur co-doped single-atom cobalt catalyst prepared in the present example in the SEM mode. From Figure 2 ​It can be seen that the Co, C, N and S elements in the catalyst are distributed in large quantities. Further measurement shows that the loading amount of Co is 11.2wt%, which is similar to the result of inductively coupled plasma optical emission spectrometer (ICP-OES) test (10.8wt%).

[0053] Figure 3 The spherical aberration-corrected-high-angle annular dark field-scanning transmission electron microscope (HAADF-STEM) image of the nitrogen-sulfur co-doped monatomic cobalt catalyst prepared in this example; from Figure 3 It can be seen that the active metal sites are monatomic dispersion and have high loading density.

[0054] Example 2

[0055] The present example provides a preparation method of a single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst.

[0056] (1) 1.0 g of 1-allyl-2-thiourea (8.62 mmol) and 157 mg of Co(NO3)2·6H2O (0.54 mmol, i.e. the molar ratio of 1-allyl-2-thiourea to Co(NO3)2·6H2O is 16:1) were added to 5 mL of deionized water under stirring to form a clear solution, then 1.0 g of SiO2 nanospheres were added, and the mixture was stirred in a beaker at 80℃ for 2 h, and the precursor was obtained by slow evaporation of the solvent in an oven at 60℃.

[0057] (2) The precursor of step (1) was heated to 900℃ at a heating rate of 5℃ / min under an argon atmosphere, and calcined for 3 h to obtain a calcined product.

[0058] (3) After the calcined product was naturally cooled to room temperature, the SiO2 nanosphere template was removed using a 5 mol / L NaOH solution, and acid immersion was performed in 0.1 M hydrochloric acid for 60 min to remove residual metals, then deionized water and ethanol were used for washing respectively for 3 times, and the single-layer eggshell-shaped nitrogen-sulfur co-doped monatomic cobalt catalyst (Co SA -CNS) was obtained by drying in a vacuum oven at 65℃ for 12 h.

[0059] Example 3

[0060] Compared with Example 1, the difference between the present example and Example 1 is that the addition amount of SiO2 nanospheres in the present example is 0.5 g.

[0061] Example 4

[0062] Compared with Example 1, the difference between the present example and Example 1 is that the addition amount of SiO2 nanospheres in the present example is 2 g.

[0063] Example 5

[0064] The difference between this example and Example 1 is that the calcination temperature of this example is 1000°C.

[0065] Example 6

[0066] The difference between this example and Example 1 is that this example uses CoCl2-6H2O (67 mg, 0.28 mmol) instead of Co(N03)2-6H2O.

[0067] Example 7

[0068] The difference between this example and Example 1 is that this example uses CoS04-7H2O (79 mg, 0.28 mmol) instead of Co(N03)2-6H2O.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the amount of Co(N03)2-6H2O added in this comparative example is 39 mg (0.134 mmol), i.e., the molar ratio of 1-allyl-2-thiourea to Co(N03)2-6H2O is 64:1.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that the amount of Co(N03)2-6H2O added in this comparative example is 314 mg (1.08 mmol), i.e., the molar ratio of 1-allyl-2-thiourea to Co(N03)2-6H2O is 8:1.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that the calcination temperature of this comparative example is 700°C.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Example 1 is that the calcination temperature of this comparative example is 800°C.

[0077] Test Example

[0078] 1. Performance determination of the catalysts of Examples 1-7 and Comparative Examples 1-4 in degrading sulfamethoxazole with activated peroxyacetic acid:

[0079] Peroxyacetic acid was added to the wastewater containing sulfamethoxazole (SMX) at a concentration of 10 μM to make the concentration of peroxyacetic acid 0.26 mM, and the pH of the wastewater was adjusted to 7.0 with 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution. The monatomic cobalt catalyst prepared in Examples 1 to 7 and Comparative Examples 1 to 4 was added to the above solution to make the concentration 50 mg / L, and the removal rate of sulfamethoxazole with time was recorded after stirring at room temperature for 5 minutes.

[0080] The removal rate results of Examples 1 to 2 and Comparative Examples 1 to 2 are shown in Table 1. Figure 4 As shown in Table 1, it can be seen that the molar ratio of cobalt salt to 1-allyl-2-thiourea has a significant effect on the removal rate. When the content of cobalt salt is too high (Comparative Example 1), the removal rate is 81% in 5 minutes, which may be because the high proportion of cobalt salt leads to a large amount of cobalt ion aggregation on the surface of silicon dioxide, affecting the dispersibility of cobalt. When the content of cobalt salt is too low, there are too few metal sites, and the removal rate is only 68% in 5 minutes. The removal rates of Examples 1 and 2 are both 90% in 2 minutes, and both reach 100% in 5 minutes.

[0081] The removal rate results of Examples 1, 3 to 4 are shown in Table 2. Figure 5 As shown in Table 2, it can be seen that the amount of SiO2 template also affects the final removal efficiency. The optimal value is obtained when the amount of SiO2 template is 0.1 g, and the removal rate in 5 minutes can reach 100%.

[0082] The removal rate results of Examples 1, 5 and Comparative Examples 3 to 4 are shown in Table 3. Figure 6 As shown in Table 3, it can be seen that too low a temperature (Comparative Example 3-700°C, Comparative Example 4-800°C) results in low removal efficiency, and the removal rate in 5 minutes is less than 80%. This is mainly because the low pyrolysis temperature makes it difficult for cobalt atoms to be completely dispersed.

[0083] The removal rate results of Examples 1, 6 to 7 are shown in Table 4. Figure 7 As shown in Table 4, it can be seen that different types of cobalt salts also have an effect on the degradation rate. The catalyst prepared from cobalt nitrate in Example 1 has the best catalytic performance, which may be because the complexes formed by different cobalt salts and 1-allyl-2-thiourea have different structures, which in turn affect the local coordination environment of the prepared cobalt monatomic atoms, thereby affecting their catalytic performance.

[0084] 2. Degradation experiment at different pH values:

[0085] Peracetic acid was added to wastewater containing 10 μM sulfamethoxazole to reach a concentration of 0.26 mM. The pH of the wastewater was adjusted to 4.0-10.0 using 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution, which were 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, and 10.0, respectively. The single-atom cobalt catalyst prepared in Example 1 was added to the above solution to reach a concentration of 50 mg / L. The reaction was stirred at room temperature for 5 minutes. The removal rate of sulfamethoxazole over time was as shown in the following table. Figure 8 shown.

[0086] from Figure 8 As can be seen from the data, when the pH value of the sewage was 4.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 67%. When the pH value of the sewage was 5.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 88%. When the pH value of the sewage was 6.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 99%. When the pH value of the sewage was 7.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 100%. When the pH value of the sewage was 8.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 92%. When the pH value of the sewage was 9.0, after 5 minutes of reaction at room temperature, the removal rate of p-sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was 76%. When the pH value of the wastewater was 10.0, after a 5-minute reaction at room temperature, the removal rate of sulfamethoxazole in the peracetic acid system activated by the single-atom cobalt catalyst was found to be 46%. Furthermore, it was confirmed that the peracetic acid system activated by the single-atom cobalt catalyst prepared by the present invention had a good removal effect on sulfamethoxazole within the pH range of 5.0 to 8.0, and that both strongly acidic and strongly alkaline conditions were not conducive to the reaction.

[0087] 3. Degradation experiment with different catalyst addition amounts:

[0088] Peracetic acid was added to wastewater containing 10 μM sulfamethoxazole (SMX) to a concentration of 0.26 mM. The pH of the wastewater was adjusted to 7.0 using 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution. The single-atom cobalt catalyst prepared in Example 1 was added to the above solution to concentrations of 25 mg / L, 50 mg / L, 75 mg / L, and 100 mg / L, respectively. The reaction was stirred at room temperature for 5 minutes, and the removal rate of sulfamethoxazole over time was recorded, as shown in FIG. Figure 9 As shown. Figure 9It can be seen from the figure that when the concentration of the catalyst reaches above 50 mg / L, all SMX can be removed within 5 minutes.

[0089] 4. Degradation experiment with different amounts of peracetic acid added:

[0090] Peracetic acid was added to wastewater containing 10 μM sulfamethoxazole (SMX) to achieve concentrations of 0.065 mM, 0.13 mM, 0.26 mM, and 0.52 mM, respectively. The pH of the wastewater was adjusted to 7.0 using 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution. The single-atom cobalt catalyst prepared in Example 1 was added to the above solution to achieve a concentration of 50 mg / L. The reaction was stirred at room temperature for 5 minutes, and the removal rate of sulfamethoxazole over time was recorded, as shown in FIG. Figure 10 As shown. Figure 10 It can be seen from the figure that when the concentration of peracetic acid reaches above 0.26 mM, all SMX can be removed within 5 minutes.

[0091] 5. Degradation experiments on different pollutants:

[0092] Peracetic acid was added to wastewater containing 10 μM of sulfadiazine (SDZ), sulfadimethoxine (SDM), sulfamethoxazole (SMIZ), ciprofloxacin (CIP), enrofloxacin (ENF), tetracycline (TTC), 4-chlorophenol (4-CP), and phenol (PN) to a concentration of 0.26 mM. The pH of the wastewater was adjusted to 7.0 with 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution. The single-atom cobalt catalyst prepared in Example 1 was added to the above solution to a concentration of 50 mg / L. The reaction was stirred at room temperature for 5 minutes. The removal rate of sulfamethoxazole over time was shown in the following table. Figure 11 shown.

[0093] from Figure 11 As can be seen, after approximately 5 minutes, the system activated with peracetic acid using a single-atom cobalt catalyst achieved 100% removal efficiency for sulfadiazine (SDZ), sulfadimethoxine (SDM), and tetracycline (TTC). Enrofloxacin (ENF), 4-chlorophenol (4-CP), and sulfamethoxazole (SMIZ) achieved removal rates of 97%, 97%, and 92%, respectively. Tetracycline (TTC) and phenol (PN) achieved removal rates of 90%. These results demonstrate that the advanced oxidation technology of peracetic acid activated with a nitrogen-sulfur co-doped single-atom cobalt catalyst is highly effective in degrading a variety of antibiotics, including sulfonamides, quinolones, and tetracyclines.

[0094] 6. Cyclic performance of the nitrogen-sulfur co-doped single-atom cobalt catalyst of Example 1:

[0095] The monatomic cobalt catalyst prepared in Example 1 was added to the wastewater containing sulfamethoxazole at a concentration of 10 μM to make the concentration of the peroxiacetic acid 0.26 mM, and the pH of the wastewater was adjusted to 7.0 with 0.1 mM sulfuric acid or 0.1 mM sodium hydroxide solution. The monatomic cobalt catalyst was added to the above solution to make the concentration of the catalyst 50 mg / L, and the reaction was stirred at room temperature for 5 min. The concentration of sulfamethoxazole was measured during the reaction, and the removal rate was calculated. The continuous recycling catalysis experiment of the catalyst was performed as follows: the solid catalyst after the reaction was collected by filtration, washed repeatedly with deionized water for 3-5 times, and then dried in a vacuum drying oven at 60°C. After that, the next catalytic reaction was started, and the change in the degradation of the pollutants was measured. The change in the removal rate of sulfamethoxazole during the recycling of the catalyst is shown in Table 1. Figure 12 As can be seen from Table 1, the 5 min removal rate of sulfamethoxazole in the system only decreased by about 8% after four recycling, and the removal rate was still 92%, which indicated that the monatomic cobalt catalyst prepared in the application had very good recycling property, and was beneficial to further popularization and application. Figure 12 As can be seen from Table 1, the 5 min removal rate of sulfamethoxazole in the system only decreased by about 8% after four recycling, and the removal rate was still 92%, which indicated that the monatomic cobalt catalyst prepared in the application had very good recycling property, and was beneficial to further popularization and application.

[0096] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can be variously changed and modified by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. Use of a single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst in the degradation of organic pollutants by activated peroxyacetic acid, characterized in that, The preparation method of the single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst comprises the following steps: 1-allyl-2-thiourea and a cobalt salt are dissolved in water, SiO2 nanospheres are added, heated and stirred, and a precursor is obtained after evaporation of the solvent; The precursor is calcined under inert gas protection, SiO2 is etched after calcination, and then the catalyst is obtained after acid immersion, washing and drying; The molar ratio of the cobalt salt to 1-allyl-2-thiourea is 1:(15-35), and the mass ratio of the cobalt salt to SiO2 nanospheres is 0.08:(0.5-2); The calcination temperature is 850-1000℃, and the calcination time is 2-4h; The single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst has an asymmetric Co-S / Co-N coordination structure.

2. Use according to claim 1, wherein The cobalt salt is selected from cobalt nitrate, cobalt chloride or cobalt sulfate.

3. The use according to claim 1, wherein The use amount ratio of 1-allyl-2-thiourea to water is 1g:(3-10)mL.

4. The use according to claim 1, wherein The heating and stirring temperature is 60-90℃, and the heating and stirring time is 60-180min; the evaporation temperature of the solvent is 50-70℃.

5. The use according to claim 1, characterized in that, The method for etching SiO2 is to use sodium hydroxide or potassium hydroxide solution for etching; The concentration of the sodium hydroxide or potassium hydroxide solution is 3-8mol / L.

6. The use according to claim 1, wherein The acid immersion process uses hydrochloric acid or sulfuric acid solution with a concentration of 0.05-0.5mol / L.

7. The use according to claim 1, wherein The ratio of the single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst, peroxyacetic acid and organic pollutants is (50-150)mg:(0.2-0.6)mmol:(1-15)μmol; and the concentration of the single-layer eggshell-like nitrogen-sulfur co-doped monatomic cobalt catalyst is 50-150mg / L.

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