Method for degrading antibiotic by using carbon shell coated cobalt nanoparticle catalytic material

Abstract

The application discloses a method for degrading antibiotics by using carbon shell wrapped cobalt nanoparticle catalytic material, which activates persulfate to degrade antibiotics by taking the carbon shell wrapped cobalt nanoparticle catalytic material as a catalyst, and the carbon shell wrapped cobalt nanoparticle catalytic material is prepared by calcining a CoCN precursor.Compared with conventional cobalt catalysts, the catalytic material has faster mass transfer efficiency, higher catalytic activity, stronger magnetic performance and better structural stability, can efficiently activate persulfate at a lower dosage, can realize rapid degradation of high-concentration antibiotics, has significant magnetic response characteristics, can realize rapid aggregation, separation and recovery through an external magnetic field, effectively solves the problem of difficult recovery of powder catalysts, has the advantages of simple process, convenient operation, low processing cost, high processing efficiency, good removal effect, good adaptability, green environmental protection and the like, and has high use value and good application prospect.

Description

Technical Field

[0001] This invention belongs to the field of environmental functional nanomaterials and water pollution control technology, and relates to a method for degrading antibiotics using cobalt nanoparticles encapsulated in a carbon shell as a catalytic material. Background Technology

[0002] Antibiotics are widely used in medicine, animal husbandry, and agricultural production. However, due to human activities and limited wastewater treatment efficiency, some antibiotics continue to enter natural aquatic environments. Residual antibiotics not only pose potential risks to aquatic ecosystems but also induce and accelerate the spread of drug-resistant bacteria and resistance genes through long-term selective pressure, thus threatening public health and safety. Therefore, developing efficient, green, and sustainable antibiotic pollution control and degradation technologies has become a crucial issue that urgently needs to be addressed in the field of environmental science and engineering.

[0003] Compared to hydrogen peroxide, persulfate has certain advantages in advanced oxidation processes: First, the persulfate system has a wider pH tolerance, allowing it to function under a broader range of water quality conditions, while traditional H₂O₂-based Fenton reactions are typically limited by acidic conditions; second, activated persulfate can generate active species with strong oxidizing capabilities, which is beneficial for promoting the efficient conversion of recalcitrant organic pollutants; furthermore, due to the asymmetric structure of the persulfate molecule, its activation process is relatively easier to occur, and the requirements for reaction conditions are generally lower than those for hydrogen peroxide. Therefore, designing and constructing efficient and stable persulfate activation catalysts is key to improving the performance of this type of advanced oxidation technology.

[0004] Cobalt nanoparticles have attracted widespread attention in persulfate advanced oxidation systems due to their abundant metal active sites, high electron transport capacity, and excellent redox properties. However, exposed cobalt nanoparticles typically have high surface energy, making them prone to migration, aggregation, or metal ion leaching during preparation and reaction, leading to loss of active sites and degradation of catalytic performance. Furthermore, traditional catalysts are usually dispersed in the reaction system as powders, making rapid and thorough separation difficult after the reaction using conventional sedimentation, filtration, or centrifugation methods. This not only increases subsequent processing costs but may also cause catalyst loss and secondary pollution, limiting their large-scale application.

[0005] Loading cobalt nanoparticles onto a support can improve their dispersibility, and in particular, coating the cobalt nanoparticles within the support can effectively prevent the leaching of metal ions. However, existing methods for preparing coated cobalt catalysts, which use metal-organic frameworks or polydopamine as precursors, carbonize the precursors through calcination and then coat the cobalt nanoparticles within the carbon material, have the following drawbacks: (a) the raw materials used contain oxygen, resulting in the prepared cobalt nanoparticles containing cobalt oxides, which is detrimental to improving the catalytic activity and magnetism of the catalyst; (b) the prepared carbon coating layer is too thick or too dense, leading to poor mass transfer efficiency and difficulty in improving electron transfer efficiency, which in turn makes it difficult to improve the activation efficiency. In particular, the cobalt nanoparticles being coated within the carbon framework material also result in weak magnetism, which is not conducive to rapid and thorough separation. The aforementioned drawbacks make it difficult for existing coated cobalt catalysts to efficiently activate persulfate under low dosage conditions, thus hindering the rapid and thorough degradation of antibiotics. At the same time, due to their weak magnetic properties, the catalyst recovery efficiency is low, making it difficult to improve the catalyst's reusability and consequently reduce processing costs.

[0006] For the reasons stated above, this invention is proposed. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a method for degrading antibiotics by using carbon shell-encapsulated cobalt nanoparticle catalytic materials, which is simple in process, convenient in operation, low in processing cost, high in processing efficiency, good in removal effect, good in adaptability, and green and environmentally friendly.

[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for degrading antibiotics using a carbon-shell-encapsulated cobalt nanoparticle catalytic material, wherein the method uses the carbon-shell-encapsulated cobalt nanoparticle catalytic material as a catalyst to activate persulfate to degrade the antibiotics; the carbon-shell-encapsulated cobalt nanoparticle catalytic material is prepared by calcination of CoCN precursor; the CoCN precursor is prepared by hydrothermal reaction of cobalt salt and potassium hydroxide.

[0009] In a further improvement to the above method, the calcination temperature is 500℃~1100℃; and the molar ratio of the cobalt salt to potassium hydroxide is 1:1.

[0010] In a further improvement to the above method, the calcination temperature is 600℃~800℃.

[0011] A further improvement to the above method is the preparation method of the carbon-shell-encapsulated cobalt nanoparticle catalytic material, which includes the following steps: S1. CoCN precursor was prepared using cobalt salt and potassium hydroxide as raw materials; S2. The CoCN precursor was calcined under anaerobic conditions to obtain a carbon-shell-encapsulated cobalt nanoparticle catalytic material.

[0012] A further improvement to the above method, in step S1, the preparation of the CoCN precursor using cobalt salt and potassium hydroxide as raw materials includes the following steps: (1) Dissolve the cobalt salt in formamide and stir to obtain a mixed solution; (2) Add potassium hydroxide to the mixed solution and stir to obtain the precursor solution; (3) The precursor solution was subjected to a hydrothermal reaction to obtain the CoCN precursor.

[0013] In a further improvement to the above method, in step (1), the cobalt salt is cobalt nitrate hexahydrate; the stirring is carried out at a speed of 500 rpm to 600 rpm; and the stirring time is 5 min to 10 min.

[0014] In a further improvement to the above method, in step (2), the stirring is carried out at a speed of 500 rpm to 600 rpm; and the stirring time is 5 min to 10 min.

[0015] The above method is further improved in step (3), where the temperature of the hydrothermal reaction is 150℃~200℃ and the time of the hydrothermal reaction is 8h~15h; after the hydrothermal reaction is completed, the following treatment is also included: the reaction product is washed with water and anhydrous ethanol in sequence, centrifuged at a speed of 6000rpm~10000rpm for 5min~10min, and the obtained solid product is dried under vacuum at a temperature of 60℃~80℃ for 8h~15h to obtain the CoCN precursor.

[0016] In a further improvement to the above method, in step S2, the CoCN precursor is calcined in an argon atmosphere; the heating rate during the calcination process is 3℃ / min to 8℃ / min; and the calcination time is 1 h to 3 h.

[0017] A further improvement to the above method is that the carbon-shell-encapsulated cobalt nanoparticle catalytic material comprises cobalt nanoparticles and a carbon shell encapsulating the cobalt nanoparticles.

[0018] In a further improvement to the above method, the cobalt nanoparticles have a particle size of 25 nm to 29 nm, and the carbon shell has a thickness of 3 nm to 6 nm.

[0019] A further improvement to the above method, using carbon-shell-encapsulated cobalt nanoparticles as a catalyst to activate persulfate for antibiotic degradation in wastewater, includes the following steps: The carbon-shell-encapsulated cobalt nanoparticle catalytic material was mixed with antibiotic wastewater, and persulfate was added to carry out a Fenton-like catalytic reaction to complete the degradation of antibiotics in the wastewater. The amount of carbon-shell-coated cobalt nanoparticle catalytic material added is 0.05 g to 0.1 g per liter of antibiotic wastewater; the amount of persulfate added is 0.1 g to 0.3 g per liter of antibiotic wastewater.

[0020] In a further improvement to the above method, the antibiotic in the antibiotic wastewater is at least one of sulfamethoxazole, levofloxacin, ciprofloxacin, tetracycline hydrochloride, and oxytetracycline; and the initial concentration of the antibiotic wastewater is ≤20 mg / L.

[0021] The above method is further improved in that the time for the Fenton-like catalytic reaction is 20s to 90s.

[0022] Compared with the prior art, the advantages of the present invention are as follows: (1) Existing methods for preparing precursors of carbon-encapsulated cobalt-based catalytic materials typically require the preparation of multiple solutions, with one solution being slowly added dropwise to another. This process demands high precision in terms of feeding rate, stirring conditions, and reaction uniformity. Some methods also require pH adjustment of the buffer solution before synthesis, making the process cumbersome, time-consuming, and susceptible to human error. In contrast, the CoCN precursor used in this invention is prepared by hydrothermal reaction of cobalt salt and potassium hydroxide. Its preparation process does not require complex dropwise addition or pH adjustment steps. The reactants are simply added to the reaction vessel in sequence, mixed evenly, and then directly transferred to an oven for reaction to obtain the precursor. This significantly simplifies the precursor synthesis process, reduces operational difficulty and time costs, improves the stability of material preparation and its potential for mass production, and is more conducive to subsequent engineering applications. It has the advantages of simple process, convenient operation, and good reproducibility.

[0023] (2) Existing catalytic systems based on carbon-coated cobalt catalysts for activating persulfate have shortcomings such as complex reaction conditions, low treatment efficiency, and poor degradation effect. Therefore, in the catalytic system of this invention, a carbon-shell-coated cobalt nanoparticle catalytic material is used as a catalyst to activate persulfate for antibiotic degradation. The carbon-shell-coated cobalt nanoparticle catalytic material is prepared by calcining a CoCN precursor. Compared with conventional carbon-coated cobalt catalysts, the carbon-shell-coated cobalt nanoparticle catalytic material used in this invention has faster mass transfer efficiency, higher catalytic activity, stronger magnetic properties, and better structural stability. In particular, the carbon-shell-coated cobalt nanoparticle catalytic material prepared in this invention conforms to an indirect electron transfer mechanism. Specifically, the conductive carbon shell not only protects the internal Co nanoparticles but also serves as an electron transport medium and reaction interface. The internal metallic Co regulates the electron distribution on the carbon shell surface through the Co-C interface electron coupling, enhancing its adsorption and activation capacity for persulfate. During the reaction, pollutants and persulfate can accumulate on the carbon shell surface and be absorbed through the carbon shell. It achieves rapid electron transfer, thereby promoting the generation of active species or the surface electron transfer oxidation process, reducing the ineffective consumption of free radicals by coexisting ions and natural organic matter, and improving the utilization efficiency of persulfate, the selectivity of pollutant degradation, and the overall reaction efficiency. Therefore, when used as a catalyst to activate persulfate, it can efficiently activate persulfate at room temperature, without the need for external accelerators or heating, and with a low catalyst dosage. It can also achieve rapid degradation of high-concentration antibiotic pollutants. It has the advantages of simple process, convenient operation, low treatment cost, high treatment efficiency, good removal effect, good adaptability, and green environmental protection. It has high use value and good application prospects.

[0024] (3) Existing carbon-coated cobalt nanoparticle materials have shortcomings such as weak magnetism and difficulty in rapid separation. In contrast, the carbon-coated cobalt nanoparticle catalytic material used in this invention exhibits significant strong magnetic response characteristics. When a neodymium iron boron magnet approaches the outer wall of the sample bottle for about 1.5 s, the catalytic material dispersed in the water can quickly and completely directionally aggregate towards the magnet. After further ultrasonic re-dispersion, the material can still rapidly complete directional aggregation under the action of an external magnetic field, indicating that it maintains a stable magnetic response in the process of "dispersion-magnetic separation-redispersion-re-magnetic separation" without significant magnetic property decay, irreversible magnetic agglomeration, or difficulty in redispersion. Therefore, the material of this invention not only has magnetism but also has repeatable, rapid, and complete magnetic separation and recovery capabilities. This performance significantly improves its recycling convenience, reusability, and practical engineering application potential in antibiotic wastewater treatment.

[0025] (4) In this invention, the multifaceted cubic CoCN precursor can only be synthesized by optimizing the molar ratio of cobalt salt and potassium hydroxide to 1:1. This is the key to the in-situ formation of carbon-encapsulated cobalt nanoparticles after high-temperature pyrolysis and carbonization. However, the required CoCN precursor cannot be synthesized under other molar ratio conditions. This is because the addition of potassium hydroxide can regulate the pH of the solution and thus regulate the synthesis of the precursor. However, both excessive and insufficient amounts of potassium hydroxide are not conducive to the synthesis of the multifaceted cubic precursor, which will affect the in-situ formation of the carbon shell during the subsequent calcination process.

[0026] (5) In this invention, by optimizing the calcination temperature to 500℃~1100℃, especially when the calcination temperature is 600℃~800℃, a carbon shell-encapsulated cobalt nanoparticle catalytic material with better magnetic properties and better structural stability can be obtained. This is because when the calcination temperature is too low (e.g. below 600℃), it is difficult to optimize the valence state, crystal phase, content and particle size of cobalt, resulting in poor magnetic properties of the material or even no magnetic properties. When the calcination temperature is too high (e.g. above 800℃), the thickness of the carbon shell is easily thinned, the coating effect on cobalt nanoparticles becomes worse, resulting in poor structural stability of the material. Moreover, increasing the calcination temperature does not effectively enhance the catalytic activity of the material, but it will increase energy consumption, which is not conducive to industrial application. Attached Figure Description

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0028] Figure 1 This is a scanning electron microscope image of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of the present invention.

[0029] Figure 2 This is a transmission electron microscope image of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of the present invention.

[0030] Figure 3 The image shows the XRD patterns of the carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A1, A2, A3, A4) prepared in Example 1 of this invention.

[0031] Figure 4 This is the energy dispersive X-ray spectral distribution of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of the present invention.

[0032] Figure 5 This is a comparison diagram showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A1, A2, A3, A4) and CoCN precursor on persulfate in Example 1 of the present invention.

[0033] Figure 6 This is a comparison chart showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on sulfamethoxazole under different pH conditions when activated with persulfate.

[0034] Figure 7 This is a comparison chart showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on different pollutants when activated by persulfate in Example 3 of the present invention.

[0035] Figure 8 This is a comparison diagram showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on sulfamethoxazole in the presence of different coexisting ions in Example 4 of the present invention.

[0036] Figure 9 This is a diagram showing the cyclic degradation effect of sulfamethoxazole on persulfate when activated by carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) in Example 5 of the present invention.

[0037] Figure 10 The graph shows the magnetic properties and recyclability test results of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) in Example 6 of this invention. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0039] In the following embodiments of the present invention, unless otherwise specified, the materials and instruments used are commercially available, the equipment used is conventional equipment, and the data obtained are the average values ​​of more than three repeated experiments.

[0040] Example 1 A method for degrading antibiotics using carbon-shell-encapsulated cobalt nanoparticles as a catalyst, specifically using the carbon-shell-encapsulated cobalt nanoparticles as a catalyst to activate persulfate for the degradation of sulfamethoxazole wastewater, includes the following steps: Take 60 mL of sulfamethoxazole solution with an initial pH of 5 and a concentration of 20 mg / L into a 250 mL beaker, and add 0.005 g of carbon-shell-coated cobalt nanoparticle catalytic materials (A1, A2, A3, A4). Stir for 10 min in the dark to mix evenly and allow sulfamethoxazole to reach adsorption-desorption equilibrium on the material surface. Add 8 mg of persulfate (PMS) to carry out a Fenton-like catalytic reaction for 90 s to complete the degradation of sulfamethoxazole in the water.

[0041] Control group 1: CoCN precursor was used instead of carbon shell to encapsulate cobalt nanoparticle catalytic materials, with other conditions remaining the same.

[0042] In this embodiment, the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) includes cobalt nanoparticles and a carbon shell covering their surface.

[0043] In this embodiment, the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) is prepared by calcining a CoCN precursor. The CoCN precursor is prepared by hydrothermal reaction of cobalt salt and potassium hydroxide, with a molar mass ratio of 1:1.

[0044] In this embodiment, the preparation method of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) includes the following steps: S1. Preparation of CoCN precursor, specifically: S1-1. Dissolve 0.01 mol of cobalt nitrate hexahydrate in 20 mL of formamide and stir at 550 rpm for 7 min to form a mixed solution. Then, quickly add 0.01 mol of potassium hydroxide to the mixed solution and stir at 550 rpm for 7 min to turn the mixed solution blue-purple. Transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined reactor and hydrothermally react at 170 °C for 12 h to obtain the precursor slurry.

[0045] S1-2. The precursor slurry was washed with water and anhydrous ethanol six times each. The resulting mixed solution was centrifuged at 8000 rpm for 6 min. The solid product after centrifugation was vacuum dried at 60℃ for 720 min to obtain the CoCN precursor.

[0046] S2. Preparation of carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A2) The CoCN precursor was placed in a tube furnace and calcined at 700°C under a mixed atmosphere of argon at a heating rate of 5°C / min, and held for 2 hours to obtain a carbon-shell-encapsulated cobalt nanoparticle catalytic material, denoted as A2.

[0047] In this embodiment, the preparation method of the carbon shell-encapsulated cobalt nanoparticle catalytic materials (A1, A3, A4) is basically the same as that of the carbon shell-encapsulated cobalt nanoparticle catalytic material (A2), the only difference being that the calcination temperatures in the preparation methods of the carbon shell-encapsulated cobalt nanoparticle catalytic materials (A1, A3, A4) are 500℃, 900℃, and 1100℃ respectively.

[0048] Figure 1 This is a scanning electron microscope image of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of this invention. From... Figure 1 It can be seen that the carbon shell encapsulating cobalt nanoparticle catalytic material has a spherical structure.

[0049] Figure 2This is a transmission electron microscope image of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of this invention. From... Figure 2 It can be seen that the carbon shell encapsulating cobalt nanoparticle catalytic material has a core-shell structure. The particle size of the cobalt nanoparticles is as large as 25-29 nm, while the thickness of the carbon shell is 3-6 nm.

[0050] Figure 3 The images show the XRD patterns of the carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A1, A2, A3, A4) prepared in Example 1 of this invention. Figure 3 It can be seen that the carbon-shell-encapsulated cobalt nanoparticle catalytic material prepared by this invention only has the peak of Co and there is no peak of cobalt metal oxide, proving that the synthesis of carbon-shell-encapsulated cobalt nanoparticles that can be magnetically separated and recovered is successful.

[0051] Figure 4 This is the energy-dispersive X-ray spectral distribution of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 of this invention. Figure 4 It can be seen that the carbon-shell-encapsulated cobalt nanoparticle catalytic material prepared by this invention contains carbon, nitrogen and cobalt.

[0052] As can be seen from the above results, the carbon-shell-encapsulated cobalt nanoparticle catalytic material of the present invention has been successfully prepared as a composite material.

[0053] During the reaction, 2 mL samples were taken at specified time points (e.g., 0, 15 s, 30 s, 45 s, 60 s, 75 s, and 90 s) and immediately filtered through a 0.22 μm organic phase membrane to separate the catalyst. The concentration of sulfamethoxazole in the solution was tested using high-performance liquid chromatography (HPLC), and the degradation efficiency of sulfamethoxazole by different materials was calculated. The results are as follows: Figure 5 As shown.

[0054] Figure 5 This is a comparison chart showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A1, A2, A3, A4) and CoCN precursor on persulfate in Example 1 of this invention. Figure 5It can be seen that the CoCN precursor exhibits poor Fenton-like catalytic performance for sulfamethoxazole, with a removal rate of only 62.6% after 90 s of reaction. In contrast, the carbon-shell-encapsulated cobalt nanoparticle catalytic materials (A1, A2, A3, A4) prepared in this invention achieve removal rates of 92.5%, 96.9%, 96.2%, and 96.2% for sulfamethoxazole, respectively. This demonstrates that the catalytic performance of the carbon-shell-encapsulated cobalt nanoparticle catalytic materials of this invention is far superior to that of the precursor. Furthermore, with increasing calcination temperature, the catalytic activity initially increases gradually and then tends towards equilibrium. Specifically, when the calcination temperature exceeds 700℃, the removal rate of sulfamethoxazole by the synthesized carbon-shell-encapsulated cobalt nanoparticle catalytic materials reaches 96.6%. In particular, the carbon-shell-encapsulated cobalt nanoparticle catalytic materials with a calcination temperature of 700℃ exhibit better kinetics throughout the reaction process, indicating that the carbon-shell-encapsulated cobalt nanoparticle catalytic materials of this invention can efficiently remove antibiotics from water.

[0055] Example 2 A method for degrading antibiotics using carbon-shell-encapsulated cobalt nanoparticles as a catalyst, specifically using the carbon-shell-encapsulated cobalt nanoparticles as a catalyst to activate persulfate to degrade sulfamethoxazole wastewater at different pH values, includes the following steps: Accurately weigh 5 mg of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1, and add it to 60 mL of sulfamethoxazole aqueous solution with an initial concentration of 20 mg / L, respectively, and adjust the pH to 3, 5, 7, 9, and 11. Stir magnetically for 10 min in the dark to allow sulfamethoxazole to reach adsorption-desorption equilibrium on the catalyst surface. Subsequently, add 8 mg of permonosulfate (PMS) to each system to initiate a Fenton-like catalytic reaction.

[0056] During the reaction, 2 mL samples were taken at specified time points (e.g., 0, 15 s, 30 s, 45 s, 60 s, 75 s, and 90 s) and immediately filtered through a 0.22 μm organic phase membrane to separate the catalyst. The concentration of sulfamethoxazole in the solution was determined using high-performance liquid chromatography (HPLC), and the degradation efficiency of the magnetically separable and recoverable carbon-shell-coated cobalt nanoparticle catalyst for sulfamethoxazole at different pH values ​​was calculated. The results are as follows: Figure 6 As shown.

[0057] Figure 6 This is a comparison graph showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on sulfamethoxazole under different pH conditions when activated with persulfate. From... Figure 6 As can be seen, the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) exhibits good removal performance across a wide pH range (3-9), indicating that the catalyst of this invention has broad practical applicability. Even under strongly alkaline conditions at pH 11, •SO4- It will be OH - It is rapidly converted to •OH, but •OH has low selectivity and a short lifespan, and is easily absorbed by CO3 in the water. 2- Such substances are consumed. Especially at pH=11, carbonate systems are more easily converted into CO3. 2- It exists in a form that may further capture free radicals, generating CO3 with relatively weak oxidizing power. - This reduces the overall degradation efficiency. Furthermore, traditional Fenton reactions and some current Fenton-like reactions cannot achieve efficient degradation of sulfamethoxazole at pH 7-11.

[0058] Example 3 A method for degrading antibiotics using carbon-shell-encapsulated cobalt nanoparticle catalytic materials, specifically using carbon-shell-encapsulated cobalt nanoparticle catalytic materials as catalysts to activate persulfate for the degradation treatment of sulfamethoxazole wastewater, levofloxacin wastewater, ciprofloxacin wastewater, tetracycline hydrochloride wastewater, oxytetracycline wastewater, carbamazepine wastewater, bisphenol A wastewater, acetaminophen wastewater, chloramphenicol wastewater, and phenol wastewater, includes the following steps: Accurately weigh 5 mg of the carbon-shell-coated cobalt nanoparticle catalyst material (A2) prepared in Example 1, and add it to sulfamethoxazole wastewater, levofloxacin wastewater, ciprofloxacin wastewater, tetracycline hydrochloride wastewater, oxytetracycline wastewater, carbamazepine wastewater, bisphenol A wastewater, acetaminophen wastewater, chloramphenicol wastewater, and phenol wastewater (each aqueous solution has a volume of 60 mL, an initial concentration of 20 mg / L, and an initial pH of 5). Stir magnetically for 10 min in the dark to allow the pollutants to reach adsorption-desorption equilibrium on the catalyst surface. Subsequently, add 8 mg of permonosulfate (PMS) to each system to initiate a Fenton-like catalytic reaction.

[0059] During the reaction, 2 mL samples were taken at specified time points (e.g., 0, 15 s, 30 s, 45 s, 60 s, 75 s, and 90 s) and immediately filtered through a 0.22 μm organic phase membrane to separate the catalyst. The concentration of pollutants in the solution was tested using high-performance liquid chromatography (HPLC), and the degradation efficiency for different pollutants was calculated. The results are as follows: Figure 7 As shown.

[0060] Figure 7 This is a comparison chart showing the degradation effects of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on different pollutants when activating persulfate in Example 3 of the present invention. Figure 7As can be seen, the carbon-shell-encapsulated cobalt nanoparticle catalytic material achieved a removal rate of over 80% for tetracycline hydrochloride, oxytetracycline, sulfamethoxazole, levofloxacin, bisphenol A, and ciprofloxacin within 90 seconds. The removal rate for atrazine, acetaminophen, chloramphenicol, and phenol exceeded 40%, indicating that the carbon-shell-encapsulated cobalt nanoparticle catalytic material of this invention has good removal effects on most pollutants and good adaptability.

[0061] Example 4 A method for degrading antibiotics using carbon-shell-encapsulated cobalt nanoparticles as a catalyst, specifically using the carbon-shell-encapsulated cobalt nanoparticles as a catalyst to activate persulfate under different coexisting ionic conditions to degrade sulfamethoxazole wastewater, includes the following steps: Accurately weigh 5 mg of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1, and add it to 60 mL of sulfamethoxazole aqueous solution with an initial pH of 5 and an initial concentration of 20 mg / L. Add chloride ions (Cl-), a common anion found in water, to the solution. - ), hydrogen phosphate ions (HPO4) - ), sulfate ions (SO4) 2- ) and bicarbonate ions (HCO3) 1- ) and carbonate ions (CO3) 2- The concentration of each catalyst was 3 mM. The mixture was magnetically stirred for 10 min in the dark to allow sulfamethoxazole to reach adsorption-desorption equilibrium on the catalyst surface. Subsequently, 8 mg of permonosulfate (PMS) was added to each system to initiate a Fenton-like catalytic reaction.

[0062] During the reaction, 2 mL samples were taken at specified time points (e.g., 0, 15 s, 30 s, 45 s, 60 s, 75 s, and 90 s) and immediately filtered through a 0.22 μm organic phase membrane to separate the catalyst. The concentration of sulfamethoxazole in the solution was determined using high-performance liquid chromatography (HPLC), and the degradation efficiency of sulfamethoxazole under different coexisting ions was calculated. The results are as follows: Figure 8 As shown.

[0063] Figure 8 This is a comparison chart showing the degradation effect of carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) on sulfamethoxazole in the presence of different coexisting ions in Example 4 of this invention. Figure 8 As can be seen, the carbon-shell-encapsulated cobalt nanoparticle catalytic material exhibits good anti-interference effects against most ions. This indicates that the carbon-shell-encapsulated cobalt nanoparticle catalytic material of this invention has strong anti-interference capabilities, which is beneficial for treating various organic pollutants in wastewater and broadens its practical application range. Furthermore, in carbonate systems, it is more likely to react with CO32-. 2-It exists in a form that may further capture free radicals, generating CO3 with relatively weak oxidizing power. - This reduces the overall degradation efficiency.

[0064] Example 5 A method for degrading antibiotics using carbon-shell-encapsulated cobalt nanoparticles as a catalyst, specifically using the carbon-shell-encapsulated cobalt nanoparticles as a catalyst to repeatedly activate persulfate for the degradation of sulfamethoxazole wastewater, includes the following steps: Accurately weigh 5 mg of the carbon-shell-coated cobalt nanoparticle catalyst material (A2) prepared in Example 1 and add it to a sulfamethoxazole aqueous solution (the volume of these aqueous solutions is 60 mL, the initial concentration is 20 mg / L, and the initial pH is 5). Stir magnetically for 10 min in the dark to allow the contaminants to reach adsorption-desorption equilibrium on the catalyst surface. Subsequently, add 8 mg of permonosulfate (PMS) to the system to initiate a Fenton-like catalytic reaction. Then, take out 95 mg of catalyst and treat it under the same experimental conditions. Mix the 5 mg of catalyst from the first reaction with the 95 mg of catalyst treated under the same conditions, filter and dry them. Take out another 5 mg of catalyst from the mixed catalyst, and repeat this process for the next cycle, for a total of 5 cycles.

[0065] Figure 9 This is a graph showing the cyclic degradation effect of sulfamethoxazole on persulfate when activated by the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) in Example 5 of the present invention. Figure 9 As can be seen, the catalytic material with carbon shell encapsulated cobalt nanoparticles, which can be magnetically separated and recovered, still maintains 95% of its performance after 5 cycles. This indicates that the catalytic material has excellent structural and catalytic stability during repeated use. These results demonstrate that the carbon shell coating effectively protects the internal cobalt nanoparticles, inhibiting the loss, aggregation, and deactivation of cobalt species, thus endowing the material with good recyclability and practical application potential.

[0066] Example 6 The magnetic properties and recyclability of carbon-shell-encapsulated cobalt nanoparticle catalytic materials were investigated, including the following steps: Accurately weigh 20 mg of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) prepared in Example 1 and disperse it in a sample bottle containing 10 mL of pure water. Sonicate or vibrate the sample bottle to ensure uniform dispersion of the catalytic material in the water, forming a stable black suspension. Then, place a neodymium iron boron magnet close to the outer wall of the sample bottle and observe the migration and enrichment of the catalytic material under the influence of an external magnetic field.

[0067] Figure 10The graph shows the magnetic properties and recyclability test results of the carbon-shell-encapsulated cobalt nanoparticle catalytic material (A2) in Example 6 of this invention.

[0068] Depend on Figure 10 It was observed that approximately 1.5 seconds after a NdFeB magnet was brought close to the outer wall of the sample vial, the carbon-shell-coated cobalt nanoparticle catalytic material dispersed in the water rapidly aggregated towards the magnet. This indicates that the carbon-shell-coated cobalt nanoparticle catalytic material prepared in this invention possesses excellent magnetic response characteristics. This magnetic response performance originates from the cobalt nanoparticles encapsulated within the carbon shell, enabling the catalytic material to be rapidly and efficiently separated and recovered using an external magnetic field after antibiotic wastewater treatment. Therefore, this invention effectively overcomes the problems of traditional powdered catalysts, such as difficulty in recovery, easy residue in water, and potential secondary pollution, thus improving the recyclability and practical application value of catalytic materials.

[0069] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for degrading antibiotics using a carbon-shell-encapsulated cobalt nanoparticle catalytic material, characterized in that, The method uses carbon-shell-encapsulated cobalt nanoparticle catalytic material as a catalyst to activate persulfate to degrade antibiotics; the carbon-shell-encapsulated cobalt nanoparticle catalytic material is prepared by calcination of CoCN precursor; the CoCN precursor is prepared by hydrothermal reaction of cobalt salt and potassium hydroxide.

2. The method according to claim 1, characterized in that, The calcination temperature is 500℃~1100℃; the molar ratio of the cobalt salt and potassium hydroxide is 1:

1.

3. The method according to claim 2, characterized in that, The calcination temperature is 600℃~800℃.

4. The method according to claim 3, characterized in that, The preparation method of the carbon-shell-encapsulated cobalt nanoparticle catalytic material includes the following steps: S1. CoCN precursor was prepared using cobalt salt and potassium hydroxide as raw materials; S2. The CoCN precursor was calcined under anaerobic conditions to obtain a carbon-shell-encapsulated cobalt nanoparticle catalytic material.

5. The method according to claim 4, characterized in that, In step S1, the preparation of the CoCN precursor using cobalt salt and potassium hydroxide as raw materials includes the following steps: (1) Dissolve the cobalt salt in formamide and stir to obtain a mixed solution; (2) Add potassium hydroxide to the mixed solution and stir to obtain the precursor solution; (3) The precursor solution was subjected to a hydrothermal reaction to obtain the CoCN precursor.

6. The method according to claim 5, characterized in that, In step (1), the cobalt salt is cobalt nitrate hexahydrate; the stirring is carried out at a speed of 500 rpm to 600 rpm; the stirring time is 5 min to 10 min. In step (2), the stirring is carried out at a speed of 500 rpm to 600 rpm; the stirring time is 5 min to 10 min. In step (3), the temperature of the hydrothermal reaction is 150℃~200℃, and the time of the hydrothermal reaction is 8h~15h. After the hydrothermal reaction is completed, the following treatment is also included: the reaction product is washed with water and anhydrous ethanol in sequence, centrifuged at a speed of 6000rpm~10000rpm for 5min~10min, and the obtained solid product is dried under vacuum at a temperature of 60℃~80℃ for 8h~15h to obtain the CoCN precursor.

7. The method according to claim 4, characterized in that, In step S2, the CoCN precursor is calcined in an argon atmosphere; the heating rate during the calcination process is 3℃ / min to 8℃ / min; the calcination time is 1 h to 3 h; the carbon shell-encapsulated cobalt nanoparticle catalytic material includes cobalt elemental nanoparticles and a carbon shell encapsulating the cobalt elemental nanoparticles.

8. The method according to any one of claims 1 to 7, characterized in that, Using carbon-shell-encapsulated cobalt nanoparticles as a catalyst to activate persulfate for antibiotic degradation in wastewater includes the following steps: The carbon-shell-encapsulated cobalt nanoparticle catalytic material was mixed with antibiotic wastewater, and persulfate was added to carry out a Fenton-like catalytic reaction to complete the degradation of antibiotics in the wastewater. The amount of carbon-shell-coated cobalt nanoparticle catalytic material added is 0.05 g to 0.1 g per liter of antibiotic wastewater; the amount of persulfate added is 0.1 g to 0.3 g per liter of antibiotic wastewater.

9. The method according to claim 8, characterized in that, The antibiotics in the antibiotic wastewater are at least one of sulfamethoxazole, levofloxacin, ciprofloxacin, tetracycline hydrochloride, and oxytetracycline; the initial concentration of the antibiotic wastewater is ≤20 mg / L.

10. The method according to claim 8, characterized in that, The time for the Fenton-like catalytic reaction is 20s to 90s.

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