Method for efficiently activating peroxymonosulfate to degrade ciprofloxacin

Abstract

This invention discloses a highly efficient method for activating peroxymonosulfate (PMS) to degrade ciprofloxacin. The method employs a cobalt- and iron-containing degradation catalytic material to activate PMS and degrade ciprofloxacin. The key feature is the preparation of a multi-cavitary bimetallic carbon framework degradation catalytic material using a metal-organic framework derivatization method. This material is supported by a carbon skeleton and chemically bonded with cobalt and iron. The prepared bimetallic carbon framework degradation catalytic material and PMS are then added to the water containing ciprofloxacin to be degraded. The bimetallic carbon framework degradation catalytic material activates the PMS, thereby degrading ciprofloxacin. This invention reduces metal leaching, improves degradation stability, and increases the efficiency of PMS activation in degrading ciprofloxacin during the degradation process. It offers advantages such as simple material preparation, low cost, convenient implementation, good catalytic degradation effect, convenient recovery, and no secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of environmental protection technology for removing antibiotics from water, specifically to a method for efficiently activating peroxymonosulfate to degrade ciprofloxacin. Background Technology

[0002] Ciprofloxacin (CIP) is a typical fluoroquinolone antibiotic, commonly used for bacterial infections. However, this class of drugs has high chemical toxicity; even low concentrations of CIP can induce changes in the genetic structure of bacteria, causing them to produce resistance genes, which can then spread through the water cycle. Therefore, excessive use of CIP can easily pollute water bodies and endanger human health. Unfortunately, traditional water treatment technologies are ineffective at degrading CIP, resulting in a high detection rate of this type of antibiotic in the aquatic environment, and these pollutants migrate during urban flooding. Therefore, developing new water treatment technologies to remove quinolone pollutants that migrate during watershed pollution and flooding is particularly important.

[0003] In recent years, advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) for pollutant degradation have attracted widespread attention. The sulfate radicals generated during PMS activation (… The redox potential (2.5-3.1V vs. NHE) is higher than that of hydroxyl radicals (·OH, 1.7-2.7V vs. NHE). Compared with ·OH, it has a wider pH tolerance range (pH = 1-9), a longer lifetime (30-40ms), and a wider range of applications. Typical methods for PMS activation include UV activation, transition metal catalyst activation, and thermal activation. Compared with other PMS activation methods, transition metal catalysis is more economical and simpler because it does not require additional energy or chemical substances, and therefore has been widely studied and applied.

[0004] Cobalt is the most effective transition metal for activating polymethyl sulfide (PMS), but its toxicity and carcinogenicity, coupled with improper recycling and treatment, can pollute water and endanger human health. Iron-based catalysts, with their advantages of low biotoxicity, strong magnetism, abundant reserves, excellent PMS catalytic activity, and metal synergistic effects, have been widely used. Therefore, introducing iron into cobalt-based catalysts to form an Fe-Co bimetallic structure may be a promising method for achieving recycling and reducing toxicity. Furthermore, due to the increased electron transfer rate, bimetallic catalysts exhibit better stability and PMS activation performance than monometallic catalysts. However, bimetallic structures still suffer from lower metal bonding strength, leading to the leaching of metal ions during use. Developing new technologies based on bimetallic structures to reduce the adverse effects of metal ion leaching in aquatic environments is essential.

[0005] Therefore, how to reduce metal leaching, improve degradation stability, and increase the efficiency of activated PMS in the degradation of ciprofloxacin has become a problem that needs further research by those skilled in the art. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a highly efficient method for degrading ciprofloxacin by activating peroxymonosulfate, which can reduce metal leaching, improve degradation stability, and increase the efficiency of activating PMS to degrade ciprofloxacin.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A highly efficient method for activating peroxymonosulfate to degrade ciprofloxacin is disclosed. This method employs a cobalt- and iron-containing degradation catalytic material to activate peroxymonosulfate and degrade ciprofloxacin. The method is characterized by first preparing a (multi-cavity) bimetallic carbon framework degradation catalytic material with a carbon skeleton as a carrier and cobalt and iron chemically bonded together using a metal-organic framework derivatization method; then adding the prepared bimetallic carbon framework degradation catalytic material and peroxymonosulfate to the water containing ciprofloxacin to be degraded, thereby utilizing the bimetallic carbon framework degradation catalytic material to activate the peroxymonosulfate and achieve the degradation of ciprofloxacin.

[0009] Thus, this method employs a carbon framework as a carrier, with cobalt and iron chemically bonded to a degradation catalytic material. This catalyzes peroxymonosulfate, enhancing its activity and achieving the degradation of ciprofloxacin in water. The co-catalysis of cobalt and iron generates a synergistic effect, improving activation. The chemical bonding between the metal and carbon material, rather than simply utilizing the pores of the carbon material for loading, better enhances the reliability of the bond between the metal and the carbon framework, better prevents secondary pollution caused by metal ion leaching during use, and ultimately improves degradation efficiency and effectiveness.

[0010] Furthermore, the prepared bimetallic carbon framework degradation catalyst is first added to the water to be degraded and mixed evenly, and then peroxymonosulfate is added to the water to be degraded and mixed evenly to complete the degradation reaction.

[0011] This is because the bimetallic carbon framework degradation catalyst is itself a porous adsorbent with strong adsorption properties. Adding this material first and mixing it thoroughly with the water to be degraded allows some ciprofloxacin to be adsorbed into the pores of the catalyst. Then, adding persulfate occurs because a catalytic activation reaction occurs between the catalyst and the persulfate, naturally attracting the persulfate. This activation of the persulfate allows for more efficient degradation of ciprofloxacin, thus significantly improving the degradation efficiency and effectiveness.

[0012] Furthermore, the ratio of the metal carbon skeleton degradation catalyst and peroxymonosulfate is such that 0.1g of metal carbon skeleton degradation catalyst and 0.5g of peroxymonosulfate are added for every 0.01g of ciprofloxacin in the water to be degraded.

[0013] This data represents the optimal ratio for verifying the degradation effect. Specifically, the applicant determined the optimal amount of catalyst material through preliminary experiments. First, 100 mL of a 20 mg / L ciprofloxacin solution was added to a 250 mL beaker. Then, to ensure that PMS was distributed and completely dissolved in the solution before the catalyst material was added, a 1 g / L PMS solution was prepared, and 100 mL of the PMS solution was added to the beaker from the previous step. The mixture was then placed on a magnetic stirrer and stirred rapidly until homogeneous (at this point, the CIP concentration in the solution was 10 mg / L and the PMS concentration was 0.5 g / L). Next, 0.02 g of catalyst material was added to the beaker (i.e., 0.1 g / L). Since the catalyst is a carbon skeleton loaded with cobalt and iron, the problem of the magnetic attraction preventing the catalyst from being uniformly dispersed in the solution needed to be considered; at the same time, excessively high rotation speed could also cause the desorption of pollutants adsorbed on the material surface. Therefore, the magnetic stirrer speed was maintained at 1000 r / min. The experiment was conducted at room temperature using a magnetic stirrer and beakers. The initial pH value was 3.5, and no pH adjustment or light exposure was required during the experiment. After stirring for several minutes, the degradation of ciprofloxacin in the water was confirmed.

[0014] Furthermore, in the bimetallic carbon skeleton degradation catalytic material, iron and cobalt are bonded to oxygen in an ionic state before being bonded to carbon, and its structural configuration is Fe / Co-OC.

[0015] In this way, iron-cobalt metal ions are bonded to oxygen, and oxygen is bonded to carbon, forming a bimetallic carbon framework catalyst. This structural formula shows that cobalt and iron are connected to carbon via oxygen as an intermediate bridge, which is consistent with XRD evidence that iron and cobalt mainly exist in oxide form, containing different valence states of iron and cobalt. Furthermore, since the bimetallic carbon framework degradation catalytic material of this application is prepared by the pyrolysis of the metal-organic framework precursor FeCo-MOFs, the precursor loses a large amount of oxygen and hydrogen during the pyrolysis process, creating numerous oxygen vacancies. Combined with iron and cobalt, these vacancies exist in a Fe / Co-OC configuration. This results in more iron and cobalt forming a dendritic structure on the periphery of the main carbon framework, not only creating greater porosity for better absorption of ciprofloxacin and peroxymonosulfate to be degraded and complete the reaction, but also facilitating contact between the peripheral iron and cobalt and peroxymonosulfate in the water outside the carbon framework to achieve catalytic action. Meanwhile, iron and cobalt are bonded to the carbon element in both divalent and trivalent ionic states, providing a variety of positively charged metal ions for activating PMS, which is more conducive to improving the activation effect and efficiency. Therefore, the Fe / Co-OC bonding makes this structure very favorable for iron and cobalt to participate in the catalytic reaction, improving the reaction efficiency while also possessing high stability and activity. It is beneficial for the two metal elements to achieve chemical bond dissociation and participate in the reaction during the reaction process, and after the reaction is completed, they can smoothly return to their original positions and re-bond with the carbon skeleton, reducing the final metal leaching amount.

[0016] From the perspective of chemical reaction principles, the mechanism by which this invention achieves the degradation of ciprofloxacin using activated peroxymonosulfate lies in the fact that peroxymonosulfate itself has limited oxidative degradation capacity. However, the degradation catalyst material of this invention (characterized as FeCo-NB@C, where FeCo indicates the presence of both Fe and Co metals in the catalyst, NB represents a nano-bimetallic compound, and @C represents carbon support) already exhibits good adsorption performance for ciprofloxacin. Further mixing of the degradation catalyst material and peroxymonosulfate constructs the FeCo-NB@C activated peroxymonosulfate system, which can generate sulfate free radicals. Hydroxyl radical (·OH), superoxide radical Singlet oxygen ( 1 Reactive oxygen species such as O2 work together to degrade adsorbed (and unadsorbed) ciprofloxacin. The porous structure and Fe / Co-OC configuration of FeCo-NB@C expose more active sites, improving catalyst activity. The active sites in FeCo-NB@C are Fe / Co bimetallic sites, giving the catalyst strong electron transfer capabilities. Firstly, Fe... 2+ and Co 2+ Activated peroxymonosulfate production and ·OH. Then due to Fe 3+ / Fe 2+ and Co 3 + / Co 2+ The cyclical interaction between them can generate more The presence of ·OH enhances the degradation efficiency of ciprofloxacin. Due to the bimetallic structure, the redox reaction between Fe and Co further enhances the generation of free radicals. Furthermore, it generates free radicals by capturing dissolved oxygen in water, similar to most materials. The difference is that FeCo-NB@C itself has abundant oxygen vacancies, which can be used to activate peroxymonosulfate to produce... This greatly enhanced The amount produced and the utilization rate of peroxymonosulfate, and further generation 1 O2. Ultimately, CIP in ·OH、 and 1 Under the influence of O2, it is degraded into small molecule organic matter through piperazine epoxidation, hydroxylation, decarboxylation and other processes, and may even be mineralized into CO2 and H2O.

[0017] The process of activating PMS at the Fe and Co bimetallic sites in the bimetallic carbon framework degradation catalytic material of this invention includes the following reactions:

[0018]

[0019]

[0020]

[0021]

[0022]

[0023] Co 3+ +Fe 2+ →Co 2+ +Fe 3+ ;

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032] Furthermore, after the reaction is complete, a magnetic blade is placed into the reaction water for stirring to achieve the recovery of the bimetallic carbon skeleton degradation catalyst material.

[0033] In this way, the ferromagnetism of the material can be utilized for recycling. After being cleaned and dried (at 60°C), the recycled material can be reused while still retaining good catalytic degradation performance, thereby reducing the cost of the material.

[0034] Furthermore, the bimetallic carbon framework degradation catalytic material is prepared according to the following steps:

[0035] a. Dissolve 1 part cobalt chloride hexahydrate, 1 part ferric chloride tetrahydrate and 2 parts terephthalic acid in a mixed solution of 16 parts N,N-dimethylformamide, 1 part ethanol and 1 part pure water in the proportion of parts by mass, and stir until homogeneous.

[0036] b. The well-stirred mixture is subjected to hydrothermal reaction at 120°C for 20-30 hours (optimal 24 hours);

[0037] After the hydrothermal reaction is completed, the product is naturally cooled to room temperature, washed repeatedly with ethanol and pure water 2-3 times, centrifuged to collect the desired precipitate, and dried at 50-70 (optimal 60)℃ for 10-14 (optimal 12) hours to obtain the metal-organic framework precursor FeCo-MOFs.

[0038] The obtained metal-organic framework precursor FeCo-MOFs were pyrolyzed in a protected atmosphere at a temperature range of 400-800 degrees Celsius to generate a bimetallic carbon framework degradation catalytic material (also known as nano-bimetallic carbon material FeCo-NB@C) with cobalt and iron supported by chemical bonds on a carbon framework.

[0039] Thus, in the above steps, a hydrothermal method is first used to generate the metal-organic framework precursor FeCo-MOFs. The hydrothermal method provides a more suitable reaction space for cobalt chloride hexahydrate, ferric chloride tetrahydrate, and terephthalic acid, ensuring they are in a uniformly dispersed environment, which is conducive to the reaction. Simultaneously, the advantage of the FeCo-MOF precursor preparation method lies in the fact that, through the hydrothermal method, cobalt chloride hexahydrate, ferric chloride tetrahydrate, and terephthalic acid can undergo a chemical reaction, utilizing chemical bonds to tightly bind the Fe-Co bimetallic compounds. This allows iron and cobalt to combine in ionic form with oxygen bonds before further combining with carbon, forming a Fe / Co-OC structural configuration. This effectively reduces metal ion leaching and facilitates the participation of metal ions in the catalytic reaction. Furthermore, due to the presence of the bimetallic compounds, there is a synergistic effect between them, greatly enhancing the electron transfer rate of the catalyst and improving the PMS activation efficiency.

[0040] Next, the obtained FeCo-MOFs were pyrolyzed. Pyrolysis transforms the organic framework into a carbon skeleton support, resulting in a tighter bond between the metal particles and the support, further reducing metal ion leaching and preventing secondary pollution. This maximizes the structural stability of the Fe-Co bimetallic relationship and the efficiency of the bimetallic cycling process. Simultaneously, pyrolysis causes the organic framework to lose a significant amount of oxygen and hydrogen, creating numerous oxygen vacancies. This makes the Fe / Co-OC structure more prominent, resulting in greater porosity. The oxygen vacancies generated by pyrolysis provide the catalyst with multiple active sites. The Fe-Co bimetallic cycling and oxygen vacancies in the catalyst facilitate the full utilization of PMS, reducing resource waste. Furthermore, the oxygen vacancies generate singlet oxygen and superoxide radicals, improving CIP degradation efficiency.

[0041] Therefore, compared with other carbon-supported metal catalysts, the advantages of this method are that the metal leaching amount is small, the catalytic performance is good, and there is no need to prepare additional carbon supports. The organic framework can be converted into a carbon support by FeCo-MOFs themselves under pyrolysis conditions, thus saving raw materials.

[0042] Furthermore, in step a, ultrasonic stirring is performed for 15 minutes. This allows for rapid and uniform mixing, which is beneficial for subsequent reactions.

[0043] Furthermore, in step b, the hydrothermal reaction process includes the following chemical reaction process: the OH bond of the carboxyl group in terephthalic acid is broken as the solution temperature increases, and Fe and Co form new Fe-O / Co-O bonds with the R-COO- formed after the breakage at the breakage site.

[0044] Thus, conventional methods for preparing carbon-supported metal catalysts using pre-prepared carbon materials such as graphene and biochar as supports rely heavily on the structure and properties of the support for their catalytic performance and stability. In contrast, the FeCo-NB@C nanoscale bimetallic carbon material produced in this method primarily relies on the metal-organic framework structure generated through a prior hydrothermal reaction. The main process is a chemical reaction, resulting in stable chemical bonds between the metal and the organic framework. FeCo-NB@C, obtained through further pyrolysis of FeCo-MOFs generated in the chemical reaction, is even more stable due to the presence of these chemical bonds. Therefore, compared to conventional carbon-supported metal catalysts, the bonding between the metal and the support is stronger, and the metal leaching is less.

[0045] Simultaneously, in step d, the pyrolysis reaction causes FeCo-MOFs to lose water, leaving a carbon material framework, and the carbon material remains chemically bonded to the iron and cobalt metals. Furthermore, the presence of both divalent and trivalent iron and cobalt metals enhances the activation effect on peroxymonosulfate, thereby improving the catalytic reaction efficiency.

[0046] Furthermore, in step d, nitrogen is used for atmosphere protection, which provides better protection.

[0047] In summary, this invention can reduce metal leaching, improve degradation stability, and increase the efficiency of activated PMS in degrading ciprofloxacin during the degradation process. It has the advantages of simple material preparation method, low cost, convenient implementation, good catalytic degradation effect on pollutants, convenient recycling, and no secondary pollution. Attached Figure Description

[0048] Figure 1 Thermogravimetric analysis of FeCo-MOFs, precursors of metal-organic frameworks.

[0049] Figure 2 Performance analysis of bimetallic carbon framework degradation catalysts prepared at different pyrolysis temperatures for activating PMS degradation of ciprofloxacin.

[0050] Figure 3 Scanning electron microscope (SEM) images of the bimetallic carbon skeleton degradation catalytic material before ((a)-(b)) and after ((c)-(d)) pyrolysis during the preparation process.

[0051] Figure 4 X-ray diffraction patterns before and after pyrolysis during the preparation of bimetallic carbon framework degradation catalytic materials.

[0052] Figure 5 The infrared spectra (FTIR) of bimetallic carbon framework degradation catalysts were obtained before and after the reaction.

[0053] Figure 6Electron paramagnetic resonance (EPR) spectra of oxygen vacancies in FeCo-NB@C, a bimetallic carbon framework degradation catalytic material.

[0054] Figure 7 (a) represents the adsorption and degradation of ciprofloxacin by different catalyst systems, and (b) represents the corresponding reaction rate constants.

[0055] Figure 8 A schematic diagram of a cyclic experiment for the degradation of ciprofloxacin by PMS activated with FeCo-NB@C bimetallic carbon framework degradation catalyst. Detailed Implementation

[0056] The present invention will now be described in further detail with reference to the accompanying drawings.

[0057] Optimal Implementation: A method for efficiently activating peroxymonosulfate to degrade ciprofloxacin. This method uses a cobalt- and iron-containing degradation catalytic material to activate peroxymonosulfate and degrade ciprofloxacin. The key feature is that a bimetallic carbon skeleton degradation catalytic material is first prepared, with a carbon skeleton as a carrier and cobalt and iron chemically bonded together. Then, the prepared bimetallic carbon skeleton degradation catalytic material and peroxymonosulfate are added to the water containing ciprofloxacin to be degraded. The bimetallic carbon skeleton degradation catalytic material is used to activate the peroxymonosulfate, thereby achieving the degradation of ciprofloxacin.

[0058] Thus, this method employs a carbon framework as a carrier, with cobalt and iron chemically bonded to a degradation catalytic material. This catalyzes peroxymonosulfate, enhancing its activity and achieving the degradation of ciprofloxacin in water. The co-catalysis of cobalt and iron generates a synergistic effect, improving activation. The chemical bonding between the metal and carbon material, rather than simply utilizing the pores of the carbon material for loading, better enhances the reliability of the bond between the metal and the carbon framework, better prevents secondary pollution caused by metal ion leaching during use, and ultimately improves degradation efficiency and effectiveness.

[0059] During implementation, the prepared bimetallic carbon skeleton degradation catalyst is first added to the water body to be degraded and mixed evenly. Then, peroxymonosulfate is added to the water body to be degraded, mixed evenly, and the degradation reaction is completed.

[0060] This is because the bimetallic carbon framework degradation catalyst is itself a porous adsorbent with strong adsorption properties. Adding this material first and mixing it thoroughly with the water to be degraded allows some ciprofloxacin to be adsorbed into the pores of the catalyst. Then, adding persulfate occurs because a catalytic activation reaction occurs between the catalyst and the persulfate, naturally attracting the persulfate. This activation of the persulfate allows for more efficient degradation of ciprofloxacin, thus significantly improving the degradation efficiency and effectiveness.

[0061] In practice, the ratio of the metal carbon skeleton degradation catalyst and peroxymonosulfate is based on the amount of ciprofloxacin in the water to be degraded: 0.1g of metal carbon skeleton degradation catalyst and 0.5g of peroxymonosulfate are added.

[0062] This data represents the optimal ratio for verifying the degradation effect. Specifically, the applicant determined the optimal amount of catalyst material through preliminary experiments. First, 100 mL of a 20 mg / L ciprofloxacin solution was added to a 250 mL beaker. Then, to ensure that PMS was distributed and completely dissolved in the solution before the catalyst material was added, a 1 g / L PMS solution was prepared, and 100 mL of the PMS solution was added to the beaker from the previous step. The mixture was then placed on a magnetic stirrer and stirred rapidly until homogeneous (at this point, the CIP concentration in the solution was 10 mg / L and the PMS concentration was 0.5 g / L). Next, 0.02 g of catalyst material was added to the beaker (i.e., 0.1 g / L). Since the catalyst is a carbon skeleton loaded with cobalt and iron, the problem of the magnetic attraction preventing the catalyst from being uniformly dispersed in the solution needed to be considered; at the same time, excessively high rotation speed could also cause the desorption of pollutants adsorbed on the material surface. Therefore, the magnetic stirrer speed was maintained at 1000 r / min. The experiment was conducted at room temperature using a magnetic stirrer and beakers. The initial pH value was 3.5, and no pH adjustment or light exposure was required during the experiment. After stirring for several minutes, the degradation of ciprofloxacin in the water was confirmed.

[0063] In the bimetallic carbon skeleton degradation catalytic material, iron and cobalt are bonded to oxygen in an ionic state and then to carbon, with a structural configuration of Fe / Co-OC.

[0064] In this way, iron-cobalt metal ions are bonded to oxygen, and oxygen is bonded to carbon, forming a bimetallic carbon framework catalyst. This structural formula shows that cobalt and iron are connected to carbon via oxygen as an intermediate bridge, which is consistent with XRD evidence that iron and cobalt mainly exist in oxide form, containing different valence states of iron and cobalt. Furthermore, since the bimetallic carbon framework degradation catalytic material of this application is prepared by the pyrolysis of the metal-organic framework precursor FeCo-MOFs, the precursor loses a large amount of oxygen and hydrogen during the pyrolysis process, creating numerous oxygen vacancies. Combined with iron and cobalt, these vacancies exist in a Fe / Co-OC configuration. This results in more iron and cobalt forming a dendritic structure on the periphery of the main carbon framework, not only creating greater porosity for better absorption of ciprofloxacin and peroxymonosulfate to be degraded and complete the reaction, but also facilitating contact between the peripheral iron and cobalt and peroxymonosulfate in the water outside the carbon framework to achieve catalytic action. Meanwhile, iron and cobalt are bonded to the carbon element in both divalent and trivalent ionic states, providing a variety of positively charged metal ions for activating PMS, which is more conducive to improving the activation effect and efficiency. Therefore, the Fe / Co-OC bonding makes this structure very favorable for iron and cobalt to participate in the catalytic reaction, improving the reaction efficiency while also possessing high stability and activity. It is beneficial for the two metal elements to achieve chemical bond dissociation and participate in the reaction during the reaction process, and after the reaction is completed, they can smoothly return to their original positions and re-bond with the carbon skeleton, reducing the final metal leaching amount.

[0065] From the perspective of chemical reaction principles, the mechanism by which this invention achieves the degradation of ciprofloxacin using activated peroxymonosulfate lies in the fact that peroxymonosulfate itself has limited oxidative degradation capacity. However, the degradation catalyst material of this invention (characterized as FeCo-NB@C, where FeCo indicates the presence of both Fe and Co metals in the catalyst, NB represents a nano-bimetallic compound, and @C represents carbon support) already exhibits good adsorption performance for ciprofloxacin. Further mixing of the degradation catalyst material and peroxymonosulfate constructs the FeCo-NB@C activated peroxymonosulfate system, which can generate sulfate free radicals. Hydroxyl radical (·OH), superoxide radical These reactive oxygen species work together to degrade adsorbed (and unadsorbed) ciprofloxacin. The porous structure and Fe / Co-OC configuration of FeCo-NB@C expose more active sites, improving catalyst activity. The active sites in FeCo-NB@C are Fe / Co bimetallic sites, giving the catalyst strong electron transfer capabilities. Firstly, Fe... 2+ and Co 2+ Activated peroxymonosulfate production and ·OH. Then due to Fe 3+ / Fe 2+ and Co 3+ / Co 2+ The cyclical interaction between them can generate more The presence of ·OH enhances the degradation efficiency of ciprofloxacin. Due to the bimetallic structure, the redox reaction between Fe and Co further enhances the generation of free radicals. Furthermore, it generates free radicals by capturing dissolved oxygen in water, similar to most materials. The difference is that FeCo-NB@C itself has abundant oxygen vacancies, which can be used to activate peroxymonosulfate to produce... This greatly enhanced The amount produced and the utilization rate of peroxymonosulfate, and further generation 1 O2. Ultimately, CIP in ·OH、 and 1 Under the influence of O2, it is degraded into small molecule organic matter through piperazine epoxidation, hydroxylation, decarboxylation and other processes, and may even be mineralized into CO2 and H2O.

[0066] The process of activating PMS at the Fe and Co bimetallic sites in the bimetallic carbon framework degradation catalytic material of this invention includes the following reactions:

[0067]

[0068]

[0069]

[0070]

[0071]

[0072] Co 3+ +Fe 2+ →Co 2+ +Fe 3+ ;

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081] During implementation, after the reaction is complete, magnetic blades are placed into the reaction water for stirring to achieve the recovery of bimetallic carbon skeleton degradation catalyst materials.

[0082] In this way, the ferromagnetism of the material can be utilized for recycling. After being cleaned and dried (at 60°C), the recycled material can be reused while still retaining good catalytic degradation performance, thereby reducing the cost of the material.

[0083] The bimetallic carbon framework degradation catalytic material is prepared according to the following steps:

[0084] a. Dissolve 1 part cobalt chloride hexahydrate, 1 part ferric chloride tetrahydrate and 2 parts terephthalic acid in a mixed solution of 16 parts N,N-dimethylformamide, 1 part ethanol and 1 part pure water in the proportion of parts by mass, and stir until homogeneous.

[0085] b. The well-stirred mixture is subjected to hydrothermal reaction at 120°C for 20-30 hours (optimal 24 hours);

[0086] After the hydrothermal reaction is completed, the product is naturally cooled to room temperature, washed repeatedly with ethanol and pure water 2-3 times, centrifuged to collect the desired precipitate, and dried at 50-70 (optimal 60)℃ for 10-14 (optimal 12) hours to obtain the metal-organic framework precursor FeCo-MOFs.

[0087] The obtained metal-organic framework precursor FeCo-MOFs were pyrolyzed in a protected atmosphere at a temperature range of 400-800 degrees Celsius to generate a bimetallic carbon framework degradation catalytic material (also known as nano-bimetallic carbon material FeCo-NB@C) with cobalt and iron supported by chemical bonds on a carbon framework.

[0088] Thus, in the above steps, a hydrothermal method is first used to generate the metal-organic framework precursor FeCo-MOFs. The hydrothermal method provides a more suitable reaction space for cobalt chloride hexahydrate, ferric chloride tetrahydrate, and terephthalic acid, ensuring they are in a uniformly dispersed environment, which is conducive to the reaction. Simultaneously, the advantage of the FeCo-MOF precursor preparation method lies in the fact that, through the hydrothermal method, cobalt chloride hexahydrate, ferric chloride tetrahydrate, and terephthalic acid can undergo a chemical reaction, utilizing chemical bonds to tightly bind the Fe-Co bimetallic compounds. This allows iron and cobalt to combine in ionic form with oxygen bonds before further combining with carbon, forming a Fe / Co-OC structural configuration. This effectively reduces metal ion leaching and facilitates the participation of metal ions in the catalytic reaction. Furthermore, due to the presence of the bimetallic compounds, there is a synergistic effect between them, greatly enhancing the electron transfer rate of the catalyst and improving the PMS activation efficiency.

[0089] Next, the obtained FeCo-MOFs were pyrolyzed. Pyrolysis transforms the organic framework into a carbon skeleton support, resulting in a tighter bond between the metal particles and the support, further reducing metal ion leaching and preventing secondary pollution. This maximizes the structural stability of the Fe-Co bimetallic relationship and the efficiency of the bimetallic cycling process. Simultaneously, pyrolysis causes the organic framework to lose a significant amount of oxygen and hydrogen, creating numerous oxygen vacancies. This makes the Fe / Co-OC structure more prominent, resulting in greater porosity. The oxygen vacancies generated by pyrolysis provide the catalyst with multiple active sites. The Fe-Co bimetallic cycling and oxygen vacancies in the catalyst facilitate the full utilization of PMS, reducing resource waste. Furthermore, the oxygen vacancies generate singlet oxygen and superoxide radicals, improving CIP degradation efficiency.

[0090] Therefore, compared with other carbon-supported metal catalysts, the advantages of this method are that the metal leaching amount is small, the catalytic performance is good, and there is no need to prepare additional carbon supports. The organic framework can be converted into a carbon support by FeCo-MOFs themselves under pyrolysis conditions, thus saving raw materials.

[0091] During implementation, step a involves ultrasonic stirring for 15 minutes. This quickly achieves uniform mixing, which is beneficial for subsequent reactions.

[0092] During implementation, in step b, the hydrothermal reaction process includes the following chemical reaction process: the OH bond of the carboxyl group in terephthalic acid is broken as the solution temperature increases, and Fe and Co form new Fe-O / Co-O bonds with the R-COO- formed after the breakage at the breakage site.

[0093] Thus, conventional methods for preparing carbon-supported metal catalysts using pre-prepared carbon materials such as graphene and biochar as supports rely heavily on the structure and properties of the support for their catalytic performance and stability. In contrast, the FeCo-NB@C nanoscale bimetallic carbon material produced in this method primarily relies on the metal-organic framework structure generated through a prior hydrothermal reaction. The main process is a chemical reaction, resulting in stable chemical bonds between the metal and the organic framework. FeCo-NB@C, obtained through further pyrolysis of FeCo-MOFs generated in the chemical reaction, is even more stable due to the presence of these chemical bonds. Therefore, compared to conventional carbon-supported metal catalysts, the bonding between the metal and the support is stronger, and the metal leaching is less.

[0094] During implementation, in step d, the pyrolysis reaction causes FeCo-MOFs to lose water, leaving a carbon material framework. The carbon material remains chemically bonded to the iron and cobalt metals. Furthermore, the presence of both divalent and trivalent iron and cobalt metals enhances the activation effect on peroxymonosulfate, thereby improving the catalytic reaction efficiency.

[0095] During implementation, nitrogen is used for atmosphere protection in step d. This provides better protection.

[0096] See Figure 1-8 In order to further study and verify the process and principle of this method, the applicant conducted further experimental verification and analysis on the principle and effect of this application based on the steps of the above specific implementation.

[0097] First, the applicant conducted pyrolysis experiments on the FeCo-MOFs obtained during the above-described specific implementation process. (See attached...) Figure 1 As shown, the applicant investigated the carbonization performance of FeCo-MOFs using a N2 atmosphere pyrolysis method (30-800℃). Thermogravimetric analysis (TGA) curves revealed three weight loss stages. First, due to the desorption of adsorbed water molecules and the loss of crystal water, the mass of FeCo-MOFs decreased from 30℃ to 280℃, a decrease of 16.72%. Second, a weight loss of 35.64% occurred between 300℃ and 520℃, indicating a gradual structural change in FeCo-MOFs, forming FeCo-NB@C material. Finally, a sudden weight loss of 8.95% between 630℃ and 640℃ is likely due to the collapse of the FeCo-NB@C structure. Therefore, it is concluded that approximately 600℃ is the optimal pyrolysis temperature.

[0098] Figure 2 Performance analysis of bimetallic carbon framework degradation catalysts prepared at different pyrolysis temperatures for activating PMS degradation of ciprofloxacin. Figure 2The effect of preparation temperature (400℃-800℃) on catalytic performance was investigated. As the pyrolysis temperature increased from 400℃ to 600℃, the degradation efficiency of CIP in the FeCo-NB@C / PMS process increased from 91.19% to 99.80%. Further increasing the pyrolysis temperature to 800℃ resulted in a decrease in CIP degradation efficiency to 92.67%. (The text abruptly ends here, likely due to an incomplete sentence or missing information.) 400 (22.74%) and FeCo-NB@C 800 Compared to (24.96%), FeCo-NB@C600 exhibits the highest adsorption capacity (33.97%), corresponding to the highest CIP degradation efficiency. (Combined) Figure 1 Thermogravimetric analysis confirmed that higher temperatures would damage the structure of FeCo-NB@C, thereby reducing the catalyst's activity. Therefore, FeCo-NB@C was selected for the CIP degradation experiment. 600 (i.e., the bimetallic carbon skeleton degradation catalytic material obtained by pyrolysis at 600℃) was used as a PMS catalyst.

[0099] Figure 3 The results, presented using scanning electron microscopy, show the changes in the apparent structure of the catalyst before and after pyrolysis. During pyrolysis, iron-cobalt ions and organic ligands are transformed into metal hybrid particles and a carbon matrix, respectively. As shown in Figures (a)-(b), FeCo-MOF consists of spindle-shaped crystals with nanoparticles aggregated on its surface. Figures (c)-(d) show FeCo-NB@C 600 Morphological and structural characteristics. FeCo-NB@C 600 The surface is not as smooth as that of FeCo-MOFs, indicating the formation of numerous defects during pyrolysis. Spherical nanoparticles are uniformly dispersed and embedded within a loose, porous carbon support. Exposed metal sites and structures facilitate the oxidation of organic pollutants. These results suggest that the pyrolysis process leads to the carbonization and partial collapse of FeCo-MOFs, forming porous, carbon-loaded iron-cobalt oxide nanoparticles.

[0100] Figure 4 X-ray diffraction patterns of the bimetallic carbon framework degradation catalytic material before and after pyrolysis during preparation. (Refer to...) Figure 4The applicant used X-ray diffraction patterns to study the crystal structure and phase composition of FeCo-MOFs and FeCo-NB@C at different temperatures. The diffraction pattern of FeCo-MOFs was basically consistent with previous studies, indicating that the MOF material was successfully prepared. The diffraction peaks of FeCo-NB@C were located at 30.09° (220), 35.44° (311), 43.06° (400), 53.45° (422), 56.98° (511), 62.59° (440), and 74.27° (533), which can be easily correlated with spinel CoFe2O4 (JCPDS, No. 22-1086). These results indicate that the structure of the material changed significantly before and after pyrolysis, indicating that the MOF derivative was successfully formed. Compared with FeCo-NB@C... 400 In comparison, FeCo-NB@C 600 and FeCo-NB@C 800 A distinct CoFe peak was observed (JCPDS, No. 49-1568). This indicates that iron and cobalt in the catalyst exist not only as metal oxides but also as metal particles. This is consistent with the SEM analysis results, meaning that FeCo-NB@C is actually a composition of CoFe2O4, FeCo nanoparticles, and carbon. Thus, iron and cobalt exist in multiple valence ionic states, enabling better activation of PMS at the metal active sites. Furthermore, the oxidation-reduction reactions between metals facilitate the cycling of metal valence states, promoting PMS activation and generating more free radicals, thereby achieving efficient CIP degradation. This is beneficial for future researchers to prepare catalysts with superior performance based on structure and different metal configurations.

[0101] Figure 5 The Fourier Transmission Infrared (FTIR) spectra of the bimetallic carbon framework degradation catalyst were obtained before and after the reaction. (Refer to...) Figure 5 :FeCo-NB@C 600 FTIR spectra such as Figure 5 As shown. 3419cm -1 The absorption peak at 2811 cm⁻¹ is caused by the stretching vibration of the -OH group. -1 The characteristic peak at 1595 cm⁻¹ belongs to the stretching vibration of the CH group. -1 1345cm -1 and 760cm -1 The bonds represent C=C, CO, and CH, respectively. The 573 cm⁻¹ peak is attributed to the Fe-O / Co-O group, indicating that the Fe / Co ions have successfully reacted with the carboxyl group of terephthalic acid to form a new chemical bond. At 573 cm⁻¹... -1The Fe-O / Co-O peak became sharper after three repeated reactions, likely due to metal precipitation making more metal bonds easier to detect. Furthermore, the peaks of other functional groups showed little change after three reactions, indicating the material's stability.

[0102] Figure 6 Electron paramagnetic resonance (EPR) spectra of oxygen vacancies in the bimetallic carbon framework degradation catalyst FeCo-NB@C. (Refer to...) Figure 6 The EPR spectrum exhibits a central symmetry line with a g-factor of 2.003, indicating that FeCo-NB@C 600 The presence of oxygen vacancies indicates that FeCo-NB@C can activate PMS not only through metal sites but also through oxygen vacancies, increasing the active sites and free radical generation pathways of the catalyst. This has a significant effect on improving CIP removal efficiency and PMS utilization, and is of great importance to the development of novel water treatment technologies.

[0103] Figure 7 (a) shows the adsorption and degradation of ciprofloxacin for different catalyst systems, and (b) shows the corresponding reaction rate constants. (Refer to...) Figure 7 The applicant investigated the catalytic performance of FeCo-NB@C and FeCo-MOFs on the PMS-activated degradation of CIP. For example... Figure 7 As shown in (a), within 15 min, FeCo-NB@C 600 FeCo-MOFs, FeCo-NB@C 600 The CIP removal rates of the FeCo-MOFs / PMS and FeCo-MOFs / PMS processes were 16.49%, 3.32%, 99.80%, and 79.24%, respectively. Furthermore, the CIP degradation in all processes followed pseudo-first-order kinetics. Figure 7 (b) Displaying FeCo-NB@C 600 rate constant (k) for adsorption removal of CIP obs The value is 0.0071 min. -1 , for FeCo-MOFs (0.0022 min) -1 The result shows that the FeCo-NB@C prepared by pyrolysis is 3.2 times that of the original product. 600 It exhibits good adsorption performance, which is attributed to the more developed pore structure of FeCo-NB@C. Meanwhile, FeCo-NB@C... 600 / PMS process k obs Reached 0.4170 min -1 The two processes are FeCo-MOFs / PMS (0.0889 min). -1 ) and PMS separate process (0.0017min) -1The results showed that FeCo-NB@C was 4.7 times and 245.3 times higher than that of other materials. 600 It exhibits high PMS activation efficiency. FeCo-NB@C 600 There is a significant synergistic effect between FeCo-NB@C and PMS processes. 600 The synergy index (SI) for CIP removal by the PMS process is 4.6.

[0104] Figure 8 A schematic diagram of a cyclic experiment for the degradation of ciprofloxacin by PMS using the bimetallic carbon framework degradation catalyst FeCo-NB@C. (Refer to...) Figure 8 The applicant studied FeCo-NB@C 600 To test its stability and reusability, and to examine its potential practicality. FeCo-NB@C 600 It has the advantage of being easy to recycle; in this process, FeCo-NB@C 600 After 10 minutes of magnetic adsorption, a simple and quick recycling process was achieved. FeCo-NB@C 600 The CIP removal rate of the / PMS process decreased slightly with increasing reuse (from 99.80% to 81.65%). After three cycles, FeCo-NB@C 600 It still maintains excellent catalytic performance, indicating that it has strong reusability as an activator for CIP removal by PMS.

[0105] Therefore, in the method of this invention, an iron-cobalt-carbon catalytic material with abundant oxygen vacancies is first prepared. This material exhibits magnetic separation and recovery capabilities, can efficiently activate PMS, and shows a significant synergistic effect with PMS. The FeCo-NB@C... 600 Combined with PMS, it is used to degrade ciprofloxacin. FeCo-NB@C 600 The PMS process has advantages such as high efficiency, recyclability, and strong adaptability in degrading ciprofloxacin.

Claims

1. A method for efficiently activating peroxymonosulfate to degrade ciprofloxacin, wherein the method employs a cobalt- and iron-containing degradation catalyst to activate peroxymonosulfate and degrade ciprofloxacin, characterized in that, First, a bimetallic carbon framework degradation catalytic material with a carbon skeleton as a carrier and cobalt and iron loaded by chemical bonding was prepared by metal-organic framework derivatization. Then, the prepared bimetallic carbon framework degradation catalytic material and peroxymonosulfate were added to the water body containing ciprofloxacin to be degraded. The peroxymonosulfate was activated by the bimetallic carbon framework degradation catalytic material to achieve the degradation of ciprofloxacin. In the bimetallic carbon skeleton degradation catalytic material, iron and cobalt are bonded to oxygen in an ionic state before being bonded to carbon, and its structural configuration is Fe / Co-OC.

2. The method for efficiently activating peroxymonosulfate to degrade ciprofloxacin as described in claim 1, characterized in that, First, the prepared bimetallic carbon skeleton degradation catalyst is added to the water to be degraded and mixed evenly. Then, peroxymonosulfate is added to the water to be degraded and mixed evenly to complete the degradation reaction.

3. The method for efficiently activating peroxymonosulfate to degrade ciprofloxacin as described in claim 2, characterized in that, The ratio of the bimetallic carbon skeleton degradation catalyst and peroxymonosulfate is based on the amount of ciprofloxacin in the water to be degraded: 0.1 g of bimetallic carbon skeleton degradation catalyst and 0.5 g of peroxymonosulfate are added for every 0.01 g of ciprofloxacin in the water.

4. The method for efficiently activating peroxymonosulfate to degrade ciprofloxacin as described in claim 1, characterized in that, After the reaction is complete, a magnetic blade is placed into the reaction water for stirring to achieve the recovery of bimetallic carbon skeleton degradation catalyst material.

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