Silkworm cocoon-shaped zinc silicate nanoparticles as well as preparation method and application thereof
By preparing cocoon-shaped zinc silicate nanoparticles as a catalyst, the problems of high metal ion dissolution rate and narrow pH range of traditional metal oxide activators when activating persulfate were solved, achieving efficient degradation and stability of tetracycline antibiotics and expanding the pH range.
Patent Information
- Application Number
- CN202511173624.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-28
AI Technical Summary
In existing technologies, traditional metal oxide activators have problems such as high metal ion dissolution rate and narrow pH range when activating persulfate for the degradation of tetracycline antibiotics, making it difficult to achieve efficient removal.
Using cocoon-shaped zinc silicate nanoparticles as a catalyst, a multi-level nanostructure is constructed through the strong coordination of zinc ions and silicate ions. Combined with a precise hydrothermal synthesis process, cocoon-shaped zinc silicate nanoparticles with unique electronic structure and porous hollow layered structure are prepared. These nanoparticles are used as a non-radical pathway catalyst to activate persulfate, expand the applicable pH range, and improve catalytic activity.
It achieves highly efficient removal of tetracycline antibiotics with a degradation rate of 99.07%, maintains high efficiency over a wide pH range, and exhibits good stability and recyclability, thus solving the environmental risks and efficiency bottlenecks of traditional catalysts.
Smart Images
Figure CN121020599A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of activated oxidants, and particularly relates to cocoon-like zinc silicate nanoparticles, a preparation method and application thereof. BACKGROUND
[0002] With the wide application of antibiotics, especially tetracycline antibiotics, in the fields of agriculture and medicine, serious water pollution problems have been caused. The existing methods for treating antibiotic wastewater, such as physical method, chemical method and biological method, all have limitations. The physical method is difficult to completely remove organic pollutants, and is easy to cause secondary pollution. The biological method is difficult to be biodegraded due to the antibacterial property of antibiotics, and the like. Moreover, these methods often have the disadvantages of long treatment period, high energy consumption, complex operation and the like. The advanced oxidation technology in the chemical method better avoids these limitations, and thus plays a huge role in treating organic pollutants in water. In the current advanced oxidation technology, the advanced oxidation technology based on persulfate (PMS) has become a research hotspot due to its high efficiency and strong oxidation capacity. However, if the persulfate (PMS) directly reacts with the organic pollutants, the oxidation effect is not significant, so it is necessary to select an appropriate way to activate the oxidant.
[0003] In the prior art, although the traditional metal oxide activated oxidant (such as Fe3O4 and Co3O4) has high catalytic activity, it generally has the problems of high metal ion leaching rate and narrow pH application range. Therefore, it is of great significance to develop a cocoon-like zinc silicate nanoparticle which can reduce the risk of metal ion leaching, expand the pH application range and activate the persulfate for degrading tetracycline antibiotics, on the premise of realizing the efficient removal of tetracycline antibiotics. SUMMARY
[0004] In view of the above problems in the prior art, the present application aims to provide a cocoon-like zinc silicate nanoparticle, a preparation method and application thereof, which can reduce the risk of metal ion leaching, expand the pH application range and activate the persulfate for realizing the efficient removal of tetracycline antibiotics on the premise of realizing the efficient removal of tetracycline antibiotics.
[0005] To solve the above technical problems, the present application provides a preparation method of cocoon-like zinc silicate nanoparticles, comprising the following steps: configuring a zinc salt aqueous solution; configuring a tetraethyl silicate solution; mixing the zinc salt aqueous solution and the tetraethyl silicate solution, and adjusting the pH to 7.0 to obtain a mixed solution; obtaining a precipitate after the mixed solution is reacted in a hydrothermal reaction at a temperature of 180℃-200℃ for 12h-18h; washing and drying the precipitate to obtain the cocoon-like zinc silicate nanoparticles.
[0006] Preferably, the molar concentration of the aqueous zinc salt solution is 36-108 mmol / L, and the concentration of the tetraethyl orthosilicate solution is 36 mmol / L.
[0007] When the molar concentration of the aqueous zinc salt solution is less than 36 mmol / L, SiO2 will be formed due to the lack of zinc ions in the reaction system.
[0008] When the temperature is lower than 180℃ and the reaction time is less than 12h, the cocoon-shaped structure cannot be formed; when the temperature is higher than 200℃ and the reaction time is greater than 18h, the cocoon-shaped structure will be broken.
[0009] Preferably, the volume ratio of the aqueous zinc salt solution to the tetraethyl orthosilicate solution is 1:1-3:1.
[0010] When the volume ratio of the aqueous zinc salt solution to the tetraethyl orthosilicate solution is less than 1:1, the zinc ions are insufficient, and SiO2 will be formed; when the volume ratio of the aqueous zinc salt solution to the tetraethyl orthosilicate solution is greater than 3:1, zinc hydroxide impurities will be formed.
[0011] Preferably, the zinc salt is any one or several of Zn(NO3)2·6H2O, ZnCl2 or ZnSO4.
[0012] Preferably, the precipitate is washed by centrifugation using deionized water and anhydrous ethanol, and the washed precipitate is dried at 60℃ for 24h for standby.
[0013] The application also provides a cocoon-shaped zinc silicate nanoparticle prepared by the preparation method of the cocoon-shaped zinc silicate nanoparticle.
[0014] The application provides an application of the cocoon-shaped zinc silicate nanoparticle activated by a persulfate salt in degrading tetracycline antibiotics.
[0015] Preferably, the degradation rate of the tetracycline is ≥99.07%.
[0016] Compared with the prior art, the application has the following beneficial effects: The cocoon-like zinc silicate nanoparticles prepared by the cocoon-like zinc silicate nanoparticle preparation method provided by the application belong to nanometer metal silicates (namely Zn2SiO4), and the zinc ions in the metal silicates have a unique electronic structure, can form a stable silicate crystal lattice structure through metal coordination with silicic acid, and thus the metal dissolution risk is reduced. Moreover, the cocoon-like zinc silicate nanoparticles usually have a porous hollow layered structure, and the nanometer-sized cocoon-like zinc silicate also significantly increases the specific surface area, provides more exposed active sites, and thus further improves the contact efficiency of the cocoon-like zinc silicate nanoparticles and the catalytic reaction of persulfate, enhances the catalytic reaction activity of the cocoon-like zinc silicate nanoparticles, and thus realizes efficient removal of tetracycline antibiotics. In addition, the Zn2SiO4-activated PMS (persulfate) reaction for degrading tetracycline (TC) is a non-radical reaction, has small dependence on pH, and thus the applicable pH range is expanded.
[0017] The cocoon-like zinc silicate nanoparticles prepared by the cocoon-like zinc silicate nanoparticle preparation method provided by the application can provide efficient and stable catalyst performance for PMS (persulfate), and realize efficient removal of tetracycline antibiotics. This is because the cocoon-like zinc silicate prepared by the preparation method provided by the application has a unique hollow spherical structure composed of nanofibers, and exhibits excellent catalytic performance in the process of activating PMS (persulfate) and degrading tetracycline (TC), so that the degradation rate of TC reaches 99.07%.
[0018] The cocoon-like zinc silicate nanoparticles prepared by the application have good stability, strong anti-interference property to changes in pH and inorganic anions, and good recyclability and reusability. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 The scanning electron microscope (SEM) image of the cocoon-like zinc silicate nanoparticles.
[0020] Figure 2 The X-ray diffraction (XRD) image of the cocoon-like zinc silicate nanoparticles.
[0021] Figure 3 The Fourier transform infrared spectrum (FTIR) image of the cocoon-like zinc silicate nanoparticles.
[0022] Figure 4 The degradation graph of tetracycline (TC) under different PMS concentrations.
[0023] Figure 5 The degradation graph of tetracycline (TC) under different cocoon-like zinc silicate nanoparticle (catalyst) concentrations.
[0024] Figure 6 The degradation graph of tetracycline (TC) under different concentrations.
[0025] Figure 7 The degradation graph of tetracycline (TC) at different pH values.
[0026] Figure 8 The degradation graph of tetracycline (TC) in different inorganic anion environments.
[0027] Figure 9 The stability test graph of cocoon-shaped zinc silicate nanoparticles (catalyst).
[0028] Figure 10 The degradation graph of tetracycline (TC) in actual aquaculture wastewater.
[0029] Figure 11 The degradation graph of tetracycline (TC) under the coexistence of other organic pollutants. DETAILED DESCRIPTION
[0030] The technical solutions in the embodiments of the present application will be clearly and completely described in the embodiments of the present application in combination with the preferred embodiments and the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.
[0031] It should be noted that all the professional terms used in the present application are only for the purpose of describing the specific embodiments and are not intended to limit the protection scope of the present application. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present application can be purchased from the market or prepared by the existing method.
[0032] The existing catalysts have the technical defects of high metal leaching rate and poor pH adaptability when activating persulfate (PMS) to degrade antibiotics. The strong coordination effect of zinc ions and silicate ions is used to construct cocoon-shaped multi-level nano-structured zinc silicate particles (Zn2SiO4), combined with a precise hydrothermal synthesis process (pH=7.0, zinc salt concentration 36mmol / L~108mmol / L, volume ratio of zinc salt / TEOS 2:1, reaction temperature 180℃~200℃, reaction time 12h~18h). The material, as a new type of non-radical pathway catalyst, can efficiently activate PMS to degrade tetracycline antibiotics (degradation rate ≥99.07%) in a wide pH range (3~9) and in the presence of interfering ions, and maintain a degradation rate of >99% in actual aquaculture wastewater and the activity attenuation is only 0.8% after 5 cycles, solving the environmental risk and efficiency bottleneck of traditional metal oxide catalysts.
[0033] The technical solutions of the present application are further illustrated in the form of specific examples. It has been found through experiments that any one of Zn(NO3)2·6H2O, ZnCl2 or ZnSO4 can be used to prepare cocoon-like zinc silicate nanoparticles by the method for preparing cocoon-like zinc silicate nanoparticles. The following examples of the method for preparing cocoon-like zinc silicate nanoparticles are based on Zn(NO3)2·6H2O.
[0034] Example 1 A method for preparing cocoon-like zinc silicate nanoparticles, comprising the following steps: 3.6 mmol of Zn(NO3)2·6H2O was dissolved in 50 mL of deionized water to obtain a Zn(NO3)2·6H2O aqueous solution with a molar concentration of 72 mmol / L; According to a volume ratio of 2:1, 36 mmol / L of a tetraethyl orthosilicate (TEOS) solution was added to the 72 mmol / L Zn(NO3)2·6H2O aqueous solution for mixing, and ammonia water was used to adjust the pH to 7.0 to obtain a mixed solution; The mixed solution was sealed in a polytetrafluoroethylene-lined autoclave, and hydrothermal reaction was performed at 200℃ for 12 h to obtain a precipitate; The precipitate was washed by centrifugation using deionized water and anhydrous ethanol to remove residual ions, and the washed precipitate was dried at 60℃ for 24 h to obtain cocoon-like zinc silicate nanoparticles.
[0035] Example 2 A method for preparing cocoon-like zinc silicate nanoparticles, comprising the following steps: 1.8 mmol of Zn(NO3)2·6H2O was dissolved in 50 mL of deionized water to obtain a Zn(NO3)2·6H2O aqueous solution with a molar concentration of 36 mmol / L; According to a volume ratio of 1:1, 36 mmol / L of a tetraethyl orthosilicate (TEOS) solution was added to the 36 mmol / L Zn(NO3)2·6H2O aqueous solution for mixing, and ammonia water was used to adjust the pH to 7.0 to obtain a mixed solution; The mixed solution was sealed in a polytetrafluoroethylene-lined autoclave, and hydrothermal reaction was performed at 180℃ for 15 h to obtain a precipitate; The precipitate was washed by centrifugation using deionized water and anhydrous ethanol to remove residual ions, and the washed precipitate was dried at 80℃ for 18 h to obtain cocoon-like zinc silicate nanoparticles.
[0036] Example 3 A method for preparing cocoon-like zinc silicate nanoparticles, comprising the following steps: 5.4 mmol of Zn(NO3)2·6H2O was dissolved in 50 mL of deionized water to obtain a 108 mmol / L Zn(NO3)2·6H2O aqueous solution; According to a volume ratio of 3:1, the 108 mmol / L Zn(NO3)2·6H2O aqueous solution was added to a 36 mmol / L tetraethyl orthosilicate (TEOS) solution and mixed, and the pH was adjusted to 7.0 by ammonia water to obtain a mixed solution; The mixed solution was sealed in a polytetrafluoroethylene-lined autoclave and hydrothermally reacted at 190℃ for 18 h to obtain a precipitate; The precipitate was washed by centrifugation using deionized water and anhydrous ethanol to remove residual ions, and the washed precipitate was dried at 70℃ for 20 h to obtain cocoon-shaped zinc silicate nanoparticles.
[0037] Example 4 The difference between this example and Example 1 is only the hydrothermal reaction temperature and the hydrothermal reaction time. In this example, the hydrothermal reaction temperature is 180℃ and the hydrothermal reaction time is 18 h.
[0038] Example 5 The difference between this example and Example 1 is only the hydrothermal reaction temperature and the hydrothermal reaction time. In this example, the hydrothermal reaction temperature is 190℃ and the hydrothermal reaction time is 15 h.
[0039] Example 6 The difference between this example and Example 1 is only the drying temperature and drying time of the washed precipitate. In this example, the drying temperature is 80℃ and the drying time is 18 h.
[0040] Example 7 The difference between this example and Example 1 is only the drying temperature and drying time of the washed precipitate. In this example, the drying temperature is 70℃ and the drying time is 20 h.
[0041] The cocoon-shaped zinc silicate nanoparticles were prepared in Examples 1-7 above. The performance of the cocoon-shaped zinc silicate nanoparticles prepared in Example 1 in activating persulfate to degrade antibiotics was analyzed.
[0042] The experiment adopts the silkworm cocoon-shaped zinc silicate nanoparticles prepared in Example 1 as an activator of persulfate PMS, adopts TC solution as a pollutant, and adopts persulfate PMS as an oxidant to perform a degradation experiment. 0.008 g of zinc silicate is added to 80 mL of TC solution, is first adsorbed for 20 min, and after sampling, 0.008 g of PMS is added, and then a sample is taken every 10 min, the TC concentration is determined by using a high-performance liquid chromatograph, and the influence of different PMS dosages, different catalyst dosages, different TC initial concentrations, different initial pHs, and different inorganic anions on the degradation under the catalytic performance of the silkworm cocoon-shaped zinc silicate nanoparticles is explored.
[0043] (1) The influence of the PMS dosage on the degradation under the catalytic performance of the silkworm cocoon-shaped zinc silicate nanoparticles is explored. Since appropriately increasing the PMS dosage can improve the TC degradation efficiency, but when the PMS concentration reaches a certain value, the degradation efficiency tends to be stable, therefore, an experiment about the influence of the PMS dosage on the degradation performance is performed.
[0044] Example 8 0.008 g of silkworm cocoon-shaped zinc silicate nanoparticles is added to 80 mL of TC solution with a pH of 7 and a concentration of 0.1 g / L -1 , is first adsorbed for 20 min, and after sampling, 0 g of PMS (that is, the PMS dosage is 0 g / L -1 ) is added, and then a sample is taken every 10 min, and the TC concentration is determined by using a high-performance liquid chromatograph.
[0045] Example 9 The difference between this example and Example 8 is only that 0.008 g of PMS (that is, the PMS dosage is 0.1 g / L -1 ) is added.
[0046] Example 10 The difference between this example and Example 8 is only that 0.012 g of PMS (that is, the PMS dosage is 0.15 g / L -1 ) is added.
[0047] Example 11 The difference between this example and Example 8 is only that 0.016 g of PMS (that is, the PMS dosage is 0.2 g / L -1 ) is added.
[0048] Example 12 The difference between this example and Example 8 is only that 0.024 g of PMS (that is, the PMS dosage is 0.3 g / L -1 ) is added.
[0049] (2) Investigating the effect of catalyst dosage on the degradation performance of cocoon-shaped zinc silicate nanoparticles. Similarly, increasing the catalyst dosage can also improve degradation efficiency, but there is an optimal value beyond which the degradation efficiency no longer significantly increases. Therefore, experiments were conducted to investigate the effect of catalyst dosage on degradation performance.
[0050] Example 13 At 80 mL, pH 7, and concentration 0.1 g / L -1 0g of cocoon-shaped zinc silicate nanoparticles (0g / L) were added to the TC solution. -1 First, adsorption was performed for 20 minutes. After sampling, 0.008 g of PMS was added. Then, samples were taken every 10 minutes, and the TC concentration was determined using high performance liquid chromatography.
[0051] Example 14 The only difference between this embodiment and Example 13 is the addition of 0.004g of cocoon-shaped zinc silicate nanoparticles (0.05g L). -1 ).
[0052] Example 15 The only difference between this embodiment and Example 13 is the addition of 0.008g of cocoon-shaped zinc silicate nanoparticles (0.1g L). -1 ).
[0053] Example 16 The only difference between this embodiment and Embodiment 13 is the addition of 0.012g of cocoon-shaped zinc silicate nanoparticles (0.15g L). -1 ).
[0054] Example 17 The only difference between this embodiment and Example 13 is the addition of 0.016g of cocoon-shaped zinc silicate nanoparticles (0.2g L). -1 ).
[0055] (3) Investigate the effect of different initial TC concentrations on the degradation of cocoon-shaped zinc silicate nanoparticles under catalytic performance. When the initial TC concentration changes, the degradation efficiency of the reaction also changes, and the changes are generally different in different degradation systems.
[0056] Example 18 At 80 mL, pH 7, and concentration 2 mg / L -1 0g of cocoon-shaped zinc silicate nanoparticles (0g / L) were added to the TC solution. -1 First, adsorption was performed for 20 minutes. After sampling, 0.008 g of PMS was added. Then, samples were taken every 10 minutes, and the TC concentration was determined using high performance liquid chromatography.
[0057] Example 19 The only difference between this embodiment and Example 18 is that the concentration of the TC solution is 5 mg / L. -1 .
[0058] Example 20 The only difference between this embodiment and Example 18 is that the concentration of the TC solution is 10 mg / L. -1 .
[0059] Example 21 The only difference between this embodiment and Example 18 is that the concentration of the TC solution is 20 mg / L. -1 .
[0060] (4) Investigate the effect of different initial pH values on the degradation performance of cocoon-shaped zinc silicate nanoparticles. Since the pH values in actual wastewater vary greatly, it is also necessary to investigate the degradation effect of the system at different pH values in order to determine the appropriate pH range.
[0061] Example 22 At 80 mL, pH 4, and a concentration of 0.1 g / L -1 0g of cocoon-shaped zinc silicate nanoparticles (0g / L) were added to the TC solution. -1 First, adsorption was performed for 20 minutes. After sampling, 0.008 g of PMS was added. Then, samples were taken every 10 minutes, and the TC concentration was determined using high performance liquid chromatography.
[0062] Example 23 The only difference between this embodiment and Embodiment 22 is that the pH value of TC is 5.
[0063] Example 24 The only difference between this embodiment and Embodiment 22 is that the pH value of TC is 6.
[0064] Example 25 The only difference between this embodiment and Embodiment 22 is that the pH value of TC is 7.
[0065] Example 26 The only difference between this embodiment and Embodiment 22 is that the pH value of TC is 8.
[0066] Example 27 The only difference between this embodiment and Embodiment 22 is that the pH value of TC is 9.
[0067] (5) Investigate the effects of different inorganic anions on the degradation of cocoon-shaped zinc silicate nanoparticles under catalytic performance. Since common inorganic anions in natural water bodies have a certain influence on the degradation of pollutants, the degradation rate of TC will be affected to different degrees when different inorganic anions are present in the system.
[0068] Example 28 At 80 mL, pH 7, and concentration 0.1 g / L -1 0.008 g of cocoon-shaped zinc silicate nanoparticles were added to the TC solution. After adsorption for 20 min, 0.008 g of PMS was added after sampling. Samples were then taken every 10 min, and the TC concentration was determined by high performance liquid chromatography.
[0069] Example 29 The only difference between this embodiment and Embodiment 28 is that NO3 is still present in the TC solution. - .
[0070] Example 30 The only difference between this embodiment and Embodiment 28 is that Cl is still present in the TC solution. - .
[0071] Example 31 The only difference between this embodiment and Example 28 is that HCO3 is still present in the TC solution. - .
[0072] Example 32 The only difference between this embodiment and Example 28 is that H2PO4 is still present in the TC solution. - .
[0073] (6) Stability test The used cocoon-shaped zinc silicate nanoparticles prepared in Example 1 were recovered by filtration through a 0.22 μm filter membrane, washed several times with deionized water and ethanol, and then used again in the TC degradation experiment. The degradation efficiency was recorded. After repeating the experiment five times, the change in catalyst degradation efficiency was observed.
[0074] The specific experimental steps for the TC degradation experiment are as follows: The cocoon-shaped zinc silicate nanoparticles prepared in Example 1 were used as the activator of sulfate PMS, and TC solution was used as the pollutant. Degradation experiments were conducted using sulfate PMS as the oxidant. 0.008 g of zinc silicate was added to 80 mL of TC solution. After adsorption for 20 min, 0.008 g of PMS was added after sampling. Samples were then taken every 10 min thereafter, and the TC concentration was determined using high performance liquid chromatography.
[0075] (7) Actual aquaculture wastewater experiment Example 33 At pH 7 and a concentration of 0.1 g / L -1 0.008 g of cocoon-shaped zinc silicate nanoparticles were added to 80 mL of TC-containing aquaculture tail water. After adsorption for 20 min, a sample was taken, and 0.008 g of PMS was added. Samples were then taken every 10 min, and the TC concentration was determined using high-performance liquid chromatography (HPLC). (Of which 0.1 g L...)-1 The 80 mL TC aquaculture wastewater solution was obtained by replacing the deionized water in the stability test with aquaculture tail water.
[0076] (8) Selective degradation experiment Example 34 At pH 7 and a concentration of 0.1 g / L -1 0.008 g of cocoon-shaped zinc silicate nanoparticles were added to 80 mL of TC solution. After adsorption for 20 min, 0.008 g of PMS was added after sampling. Samples were then taken every 10 min, and the TC concentration was determined by high performance liquid chromatography.
[0077] Example 35 The only difference between this embodiment and Example 28 is that Rhodamine B (RhB) is also present in the TC solution.
[0078] Example 36 The only difference between this embodiment and Example 28 is that bisphenol A (BPA) is also present in the TC solution.
[0079] Example 37 The only difference between this embodiment and Example 28 is that carbamazepine (CBZ) is also present in the TC solution.
[0080] Experimental Analysis (1) SEM images of cocoon-shaped zinc silicate nanoparticles like Figure 1 As shown, cocoon-shaped zinc silicate nanoparticles can be seen. The surface of the particles is rough and exhibits a fibrous structure. This structure may indicate that the cocoon-shaped zinc silicate nanoparticles underwent a specific growth mechanism during their formation, resulting in this unique morphology. Furthermore, the boundaries between the particles are clear, showing good separability between them.
[0081] (2) X-ray diffraction of cocoon-shaped zinc silicate nanoparticles like Figure 2 The XRD pattern of the cocoon-shaped zinc silicate nanoparticles shows that the diffraction peak positions and intensities of the cocoon-shaped zinc silicate nanoparticles are highly matched with the standard diffraction peak positions and intensities of PDF#37-1485, indicating that the sample is dominated by well-crystallized zinc silicate.
[0082] (3) Fourier transform infrared (FTIR) spectrum of cocoon-shaped zinc silicate nanoparticles like Figure 3 The FTIR image of the cocoon-shaped zinc silicate nanoparticles shown indicates that approximately 500 cm⁻¹ -1 ~600cm -1 The absorption peak at this point is usually related to the Zn-O stretching vibration, reflecting the absorption peak of Zn. 2+Coordination state with oxygen. Approximately 900 cm -1 ~1000cm -1 The absorption peak at this point is related to the antisymmetric stretching vibration of Si-O-Si in the silicon-oxygen tetrahedron, indicating that the material has a silicon-oxygen network as its main structure. The overall spectrum conforms to typical silicate characteristics, with no obvious impurity peaks, indicating that the sample has high purity.
[0083] (4) Degradation diagram of tetracycline (TC) at different PMS concentrations The TC concentrations obtained in Examples 8 to 12 were used to prepare... Figure 4 ,from Figure 4 As can be seen from this, when the concentration of PMS is 0.10 g / L... -1 At approximately 99.04% concentration, the degradation rate of TC reached approximately 99.04%. However, as the concentration of PMS further increased, the degradation rate of TC accelerated, but the degradation rate no longer increased. This may be because when the PMS concentration gradually increases from a low level, the active sites on the zinc silicate surface are not yet saturated. PMS molecules adsorb onto the zinc silicate surface, generating active species (such as...) 1 The concentration of O2 (or high-valence metal oxygen species) increases with increasing PMS concentration, leading to a higher probability of contact with TC molecules and thus a faster reaction rate. However, when the PMS concentration exceeds a critical value, the active sites of zinc silicate are completely occupied, the rate of active species generation reaches its upper limit, and the degradation rate of TC is limited to a further increase. Therefore, the PMS concentration in this system is 0.10 g / L. -1 The best time is when.
[0084] (5) Degradation of tetracycline (TC) at different catalyst dosages The TC concentrations obtained in Examples 13 to 17 were used to prepare... Figure 5 ,pass Figure 5 It can be seen that when the concentration of zinc silicate is 0.10 g / L... -1 At a concentration of approximately 0.10 g / L, efficient degradation of TC can be achieved. While the degradation rate increases with increasing zinc silicate concentration, the overall degradation rate remains relatively stable. This may be because increasing zinc silicate concentration provides more active sites for the reaction, thus accelerating the degradation process; however, when the concentration reaches 0.10 g / L... -1At this point, PMS molecules in the system have fully contacted and occupied all effective active sites. While further increasing the catalyst concentration will provide more active sites, the limited concentrations of PMS and TC in the system lead to redundancy of active sites, thus maximizing the degradation rate. Furthermore, high catalyst concentrations may cause particle agglomeration or increased system viscosity, obscuring some active sites and hindering the diffusion and adsorption of PMS and pollutants, thereby inhibiting the reaction process. This phenomenon reflects the high dependence of the non-radical pathway on the reaction interface and mass transfer efficiency, rather than simply a linear additive dependence on catalyst amount. Therefore, the zinc silicate concentration should be controlled at 0.10 g / L during degradation. -1 This ensures that the system has high catalytic performance while also taking into account the effective utilization of resources.
[0085] (6) Degradation diagram of tetracycline (TC) at different initial TC concentrations The TC concentrations obtained in Examples 18 to 21 were used to prepare... Figure 6 ,pass Figure 6 It can be seen that when the TC concentration is 10 mg / L... -1 At this time, the degradation rate and degradation rate of TC were both high, reaching 99.24%, while when the TC concentration reached 20 mg / L... -1 The degradation rate decreased significantly, but the degradation rate was not significantly affected. This may be because when the initial TC concentration is low, there are sufficient active sites on the zinc silicate surface, allowing TC molecules to be fully adsorbed and participate in surface-mediated direct electron transfer reactions, achieving efficient TC degradation. However, as the TC concentration further increases, the excess TC molecules intensify competition for active sites, making it impossible to ensure sufficient contact between TC molecules and active sites, resulting in a decrease in the degradation rate. In addition, intermediate products generated during TC degradation (such as decarboxylation or deamination compounds) preferentially adsorb onto the catalyst surface, which also hinders subsequent contact between TC molecules and active sites.
[0086] (7) Degradation diagram of tetracycline (TC) at different initial pH The TC concentrations obtained in Examples 22 to 27 were used to prepare... Figure 7 ,pass Figure 7 It can be seen that the system exhibits good degradation performance in different pH environments, with a degradation rate of approximately 99.40%, but the degradation rate is slightly faster at pH 5–7. This may be because zinc silicate has a stable surface structure over a wide pH range (pH=3–9), and its surface Zn... 2+The active sites with oxygen vacancies are highly tolerant to pH changes, and the non-radical active species generated by zinc silicate activation of PMS also have wide pH adaptability and strong anti-interference ability. These species can exist stably under acidic, neutral and alkaline conditions, avoiding the quenching of active species in the free radical pathway due to pH changes. At pH=5 to 7, the protonation level of hydroxyl groups (-OH) on the surface of zinc silicate is moderate, which is conducive to the efficient adsorption of PMS molecules on the active sites through hydrogen bonding or coordination, accelerating the generation of active species. It may also be because the intermediate products generated by TC degradation are more easily oxidized into small molecule products, reducing their accumulation on the catalyst surface, thus facilitating TC degradation.
[0087] (8) Degradation diagram of tetracycline (TC) with different inorganic anions The TC concentrations obtained in Examples 28 to 32 were used to prepare... Figure 8 ,pass Figure 8 The figure shows an inorganic anion concentration of 0.01 mol / L. -1 The degradation of TC at that time. It can be observed in NO3. - and Cl - Under the same conditions, the degradation rate and degradation speed of TC remained at a similar level to the control group, which may be due to NO3. - and Cl - It has a weak quenching ability for active species in the system and a limited binding ability to active sites on the catalyst surface, thus failing to significantly interfere with the degradation of TC; in HCO3 - Under certain conditions, TC degrades the fastest, possibly because of HCO3. - It reacts with the active species in the system to generate carbonate radicals (CO3), which have stronger oxidizing power. - ·), in H2PO4 - Under the given environment, the degradation rate and degradation percentage of TC both decreased significantly, reaching only 72.39%, which may be due to H2PO4. - It reacts with the active species in the system to generate secondary free radicals with weak oxidizing power (such as HPO3). - · or HPO4 - ·), or it could be due to H2PO4. - By preferentially occupying the active sites on the zinc silicate surface through strong coordination, TC molecules are prevented from diffusing to the catalyst surface.
[0088] (9) Stability of cocoon-shaped zinc silicate nanoparticles To evaluate the stability and reproducibility of the catalyst, five stability experiments were conducted. Figure 9It can be seen that the catalytic performance of zinc silicate is generally stable, with only a slight decrease in the last two experiments, but the decrease is only about 0.8%, and it remains generally stable. This phenomenon may be due to the presence of a small amount of active component (such as Zn) in zinc silicate during the reaction process. 2+ or SiO4 4- The dissolution of PMS molecules, or the adsorption of intermediate products generated by TC degradation on the zinc silicate surface, hinders the diffusion of PMS molecules to the active sites, but has a very small overall impact on catalyst performance.
[0089] (0) Actual aquaculture wastewater experiment passed Figure 10 The system exhibited good degradation effects in various aquaculture wastewaters, with a degradation rate reaching 99.78%, and the degradation rate in aquaculture wastewater was slightly higher than that in DI water. This may be because residual natural organic matter (such as humic acid) in aquaculture wastewater can act as an electron shuttle, promoting electron transfer via non-radical pathways; or it may be due to the presence of HCO3- in aquaculture wastewater. - It can generate CO3· - It enhances oxidation capacity, thereby improving TC degradation efficiency.
[0090] (1) Prepare the TC concentration obtained in Examples 34 to 37. Figure 11 ,pass Figure 11 The figure shows an organic pollutant concentration of 0.01 g / L. -1 The degradation of TC was observed. It was found that under RhB, BPA, and CBZ environments, the degradation rate and percentage of TC remained similar to those of the control group, indicating that the system exhibited good selectivity for TC degradation.
[0091] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.
Claims
1. A method for preparing cocoon-shaped zinc silicate nanoparticles, characterized in that, Includes the following steps: Prepare a zinc salt aqueous solution; A zinc salt aqueous solution was mixed with a tetraethyl silicate solution, and the pH was adjusted to 7.0 to obtain a mixed solution. The mixture was reacted in a hydrothermal reaction at a temperature of 180℃~200℃ for 12h~18h to obtain a precipitate; The precipitate was washed and dried to obtain cocoon-shaped zinc silicate nanoparticles.
2. The method for preparing cocoon-shaped zinc silicate nanoparticles according to claim 1, characterized in that, The molar concentration of the zinc salt aqueous solution is 36 mmol / L to 108 mmol / L, and the concentration of the tetraethyl silicate solution is 36 mmol / L.
3. The method for preparing cocoon-shaped zinc silicate nanoparticles according to claim 1, characterized in that, The volume ratio of the zinc salt aqueous solution to the tetraethyl silicate solution is 1:1 to 3:
1.
4. The method for preparing cocoon-shaped zinc silicate nanoparticles according to claim 1, characterized in that, The zinc salt is any one or more of Zn(NO3)2·6H2O, ZnCl2, or ZnSO4.
5. The method for preparing cocoon-shaped zinc silicate nanoparticles according to claim 1, characterized in that, The precipitate was washed with deionized water and anhydrous ethanol by centrifugation. The washed precipitate was then dried at 60℃~80℃ for 18h~24h for later use.
6. The cocoon-shaped zinc silicate nanoparticles prepared by the method according to any one of claims 1 to 5.
7. The application of the activated persulfate by the cocoon-shaped zinc silicate nanoparticles according to claim 6 in the degradation of tetracycline antibiotics.
8. The application of the cocoon-shaped zinc silicate nanoparticles activated persulfate according to claim 6 in the degradation of tetracycline antibiotics, characterized in that, The degradation rate of the tetracycline is ≥99.07%.