Iron modified carbon quantum dots embedded in zinc-doped porous carbon material, preparation method and application thereof

Abstract

The application discloses an iron modified carbon quantum dot embedded zinc doped porous carbon material and a preparation method and application thereof, and the preparation method comprises the following steps: dispersing polyethylene terephthalate, iron trichloride hexahydrate and triethanolamine in anhydrous ethanol, stirring and ultrasonicating to obtain a precursor solution, performing a solvothermal reaction on the precursor solution to obtain an iron modified carbon quantum dot solution, mixing the iron modified carbon quantum dot solution with polyethylene terephthalate to obtain a mixed precipitate, dropping an anhydrous ethanol solution of zinc chloride into the mixed precipitate, and drying to obtain a precursor mixture; and performing calcination on the precursor mixture to obtain the product. The iron modified carbon quantum dot embedded zinc doped porous carbon material prepared by the application has the advantages of high treatment efficiency, good removal effect, high reusability, cleanness and no pollution, and can be efficiently applied to the treatment of antibiotic wastewater.

Description

Technical Field

[0001] This invention belongs to the field of catalyst technology, and relates to an iron-modified carbon quantum dot embedded zinc-doped porous carbon material, its preparation method and application, specifically an iron-modified carbon quantum dot embedded zinc-doped porous carbon material, its preparation method and its application in antibiotic wastewater treatment. Background Technology

[0002] With the development of the medical and livestock industries, a large amount of recalcitrant organic wastewater is being discharged into the aquatic environment. Even at extremely low concentrations, the persistent pollutants carried in this wastewater can pose ecological risks. Therefore, the development of efficient and economical water treatment technologies has become an urgent need in the environmental field.

[0003] Advanced oxidation processes, membrane methods, electrochemical methods, and adsorption methods have been used to remove oxytetracycline. Among these, adsorption has the advantages of ease of operation, low cost, high efficiency, and no secondary pollution, making it highly promising for pollutant degradation. However, it is worth noting that adsorption technology cannot completely "eliminate" pollutants, while advanced oxidation technology can degrade pollutants without producing secondary pollutants. The adsorption catalyst is key to combining adsorption and advanced oxidation technologies. These materials can adsorb pollutants and then catalyze in-situ oxidation to more effectively decompose the pollutants, thereby achieving efficient pollutant removal and partial material regeneration.

[0004] Carbon-based materials are widely used in the treatment of antibiotic wastewater due to their stable structure, easy availability, and large specific surface area. However, their high preparation cost and low removal efficiency limit their application. Therefore, developing a low-cost catalyst with good removal effect is of great significance to the development of antibiotic wastewater removal technology.

[0005] Porous carbon materials (PCs) are a class of carbon-based materials with abundant pore structures, formed from carbon-rich precursors through processes such as pyrolysis, activation, or template methods. As an important functional material, porous carbon materials possess advantages such as ultra-high specific surface area, tunable pore size distribution, good electrical and thermal conductivity, excellent chemical stability, and abundant resources, making them a focus of attention in adsorption separation, electrochemical energy storage, and catalysis. Most existing technologies employ cobalt-doped porous carbon, utilizing cobalt as the active site for catalytic removal, thus enhancing the catalytic activity of porous carbon materials. However, cobalt metal is relatively scarce, increasing material costs and hindering large-scale applications. Furthermore, the degradation efficiency of the catalytic system decreases significantly under strong acid or strong alkaline conditions, indicating limited resistance to acid and alkali shocks and difficulty in coping with the complex pH fluctuations in real-world wastewater. Therefore, comprehensively improving the shortcomings of existing porous carbon materials and obtaining a porous carbon material with excellent stability, adsorption, and catalytic activity is of great significance for expanding the application range of porous carbon materials in antibiotic wastewater treatment. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an iron-modified carbon quantum dot embedded zinc-doped porous carbon material with high processing efficiency, good removal effect, high reusability and clean and pollution-free, as well as its preparation method and application.

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

[0008] A method for preparing an iron-modified carbon quantum dot embedded zinc-doped porous carbon material includes the following steps: S1. Polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine are dispersed in anhydrous ethanol, and after stirring and sonication, a precursor solution is obtained. S2. The precursor solution is subjected to a solvothermal reaction at 180℃~200℃. After the reaction, the solution is centrifuged, dialyzed and filtered to obtain an iron-modified carbon quantum dot solution. S3. The iron-modified carbon quantum dot solution is mixed with polyethylene terephthalate, and after the first stirring and sonication, it is centrifuged and washed to obtain a mixed precipitate. Anhydrous ethanol solution of zinc chloride is added dropwise to the obtained mixed precipitate, and after the second stirring and drying, a precursor mixture is obtained. S4. The precursor mixture is calcined at 600℃~700℃ under N2 atmosphere. The resulting product is washed and dried to obtain iron-modified carbon quantum dot embedded zinc-doped porous carbon material.

[0009] In the above-mentioned method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon materials, preferably, in step S1, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:1.351-5.406:0.8-1, and the mass-volume ratio of polyethylene terephthalate to anhydrous ethanol is 1g:50mL-100mL.

[0010] In the above-mentioned method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon materials, preferably, the mass ratio of polyethylene terephthalate, zinc chloride in step S3 to polyethylene terephthalate in step S1 is 1:0.682 to 1.364:1, and the mass concentration of zinc chloride in the anhydrous ethanol solution of zinc chloride is 0.068 g / mL to 0.136 g / mL.

[0011] In the above-mentioned method for preparing iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials, preferably, in step S1, the stirring speed is 300 r / min to 400 r / min, the stirring time is 20 min to 30 min, and the ultrasonication time is 20 min to 30 min; In step S2, the solvothermal reaction time is 8h to 12h, the centrifugation speed is 8500r / min to 10000r / min, the centrifugation time is 20min to 30min, the dialysis uses a 1000Da dialysis bag, the dialysis solution is water, the dialysis time is 2d to 3d, and the dialysis solution is changed every 8h to 12h.

[0012] In the preferred embodiment of the above-mentioned method for preparing iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials, in step S3, the first stirring speed is 300 r / min to 400 r / min, the first stirring time is 0.5 h to 1 h, the ultrasonication time is 0.5 h to 1 h, the centrifugation speed is 4000 r / min to 5000 r / min, the centrifugation time is 5 min to 10 min, the washing refers to washing with water and anhydrous ethanol sequentially, the number of times the water is washed is 2 to 3 times, the number of times the anhydrous ethanol is washed is 2 to 3 times, the drying temperature is 60℃ to 80℃, and the drying time is 1 h to 2 h.

[0013] In the preferred embodiment of the above-mentioned method for preparing iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials, in step S4, the heating rate is 5℃ / min to 10℃ / min, the calcination time is 2h to 3h, the washing refers to washing with water and H2SO4 solution sequentially, the number of times the water is washed is 2 to 3 times, the number of times the H2SO4 solution is washed is 2 to 3 times, the concentration of the H2SO4 solution is 1mol / L to 2mol / L, the drying is vacuum drying, the vacuum drying temperature is 60℃ to 80℃, and the vacuum drying time is 8h to 12h.

[0014] As a general technical concept, the present invention also provides a method for preparing iron-modified carbon quantum dot-embedded zinc-doped porous carbon material as described above.

[0015] Preferably, the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material comprises iron-modified carbon quantum dots and zinc-doped porous carbon, wherein the iron-modified carbon quantum dots are embedded in the zinc-doped porous carbon. More preferably, the iron-modified carbon quantum dots are further doped with nitrogen (N).

[0016] As a general technical concept, the present invention also provides an application of iron-modified carbon quantum dot embedded zinc-doped porous carbon material prepared by the above-mentioned preparation method, or the application of the above-mentioned iron-modified carbon quantum dot embedded zinc-doped porous carbon material in the treatment of antibiotic wastewater.

[0017] The above-mentioned application, preferably, includes the following steps: adding the iron-modified carbon quantum dots embedded in zinc-doped porous carbon material to antibiotic wastewater, shaking until adsorption equilibrium is reached, then adding an oxidant, and continuing to shake to carry out an advanced oxidation reaction to achieve the treatment of antibiotic wastewater; The mass-to-volume ratio of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material to the antibiotic wastewater is 0.2g-0.3g:1L. The concentration of the antibiotic wastewater is 10mg / L-20mg / L, the pH value of the antibiotic wastewater is 3-11, the antibiotic wastewater is oxytetracycline wastewater, the oscillation speed is 150r / min-200r / min, the oscillation time is 30min-60min, the oscillation speed is 150r / min-200r / min, the oscillation time is 30min-60min, the oscillation continues at 150r / min-200r / min for 30min-60min, the oxidant is potassium peroxymonosulfate complex salt, the potassium peroxymonosulfate content in the potassium peroxymonosulfate complex salt is 46%, and the addition concentration of the potassium peroxymonosulfate complex salt is 0.2g / L-0.3g / L.

[0018] Compared with the prior art, the advantages of the present invention are as follows: (1) This invention provides a method for preparing iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials. First, iron-modified carbon quantum dots are prepared using polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine. Then, the obtained iron-modified carbon quantum dots are mixed with polyethylene terephthalate and zinc chloride, and calcined and carbonized to form iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials. This invention selects polyethylene terephthalate as the carbon source, not only because its high carbon content and inherent aromatic framework are conducive to constructing highly graphitized, multi-defect porous carbon networks, but also because it aims to provide a practical technical path for plastic recycling through a "waste-to-waste" strategy. Furthermore, the preparation of iron-modified carbon quantum dots using these three raw materials has a high yield. The iron-modified carbon quantum dots prepared by the method of the present invention can provide active sites for activating potassium persulfate (PMS), while the incorporation of zinc helps to form a hierarchical porous carbon structure after calcination. Zinc-doped porous carbon serves as an effective supporting framework, which significantly improves the utilization rate of active sites of iron-modified carbon quantum dots and ultimately effectively enhances the PMS activation ability.

[0019] In the preparation method of this invention, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine was systematically optimized (preferred range: 1:1.351–5.406:0.8–1, optimal: 1:2.703:0.8) to ensure that iron ions obtain a suitable doping amount in carbon quantum dots, thereby endowing the material with excellent catalytic activity. This invention also systematically optimized the mass ratio of zinc chloride to polyethylene terephthalate to ensure the best pore structure is obtained during calcination, thereby improving catalytic performance. In this invention, the solvothermal reaction temperature is selected at 180–200°C to ensure the best quantum dot yield, thereby improving the catalytic effect; the calcination temperature is selected at 600–700°C to ensure a well-developed pore structure while preventing the collapse of the formed pore structure, thus obtaining the best catalytic effect. The preparation method of the present invention is simple to operate and has a short synthesis process. It not only has high yield and good reproducibility, but also uses few types of raw materials and has low cost, thus having good prospects for industrialization.

[0020] (2) The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material prepared by this invention has both structural advantages and functional synergistic effects. On the one hand, the doping of zinc ions effectively regulates the pore structure and specific surface area of ​​porous carbon. On the other hand, the iron-modified carbon quantum dots embedded in the pores can not only act as electron donors / acceptors to accelerate metal redox cycles and promote the generation and transport of valence band electrons, but also directly activate peroxy bonds (such as potassium persulfate) through surface defect sites. At the same time, the porous carbon matrix provides a physical isolation space for the carbon quantum dots, effectively preventing their aggregation and deactivation. More importantly, the confinement effect significantly prolongs the residence time of active free radicals and induces the generation of long-lived non-free radical species such as singlet oxygen (¹O2), thereby greatly improving the oxidant utilization efficiency and resistance to background interference. Compared with existing carbon-based materials, the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of this invention has outstanding advantages such as large specific surface area, good dispersibility, high stability, and excellent adsorption and catalytic performance.

[0021] (3) The iron-modified carbon quantum dot embedded zinc-doped porous carbon material of the present invention can be applied to the treatment of antibiotic wastewater, especially oxytetracycline wastewater. By mixing the iron-modified carbon quantum dot embedded zinc-doped porous carbon material with wastewater and performing oscillation adsorption, antibiotics can be efficiently enriched. After reaching adsorption equilibrium, advanced oxidation reactions can be directly introduced into the suspension to achieve in-situ catalytic degradation of adsorbed antibiotics. The application of the present invention integrates adsorption enrichment and catalytic degradation. It is not only simple in process, low in equipment requirements, and easy to operate, but also has high removal efficiency, good treatment effect, and the material can be reused. The whole process is clean and has no secondary pollution, which has significant environmental benefits and commercial application value. Attached Figure Description

[0022] Figure 1 Scanning electron microscope (SEM) images of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2, wherein... Figure 1 (a) is a scanning electron microscope image of PC. Figure 1 (b) is a scanning electron microscope image of Fe-CQD@PC. Figure 1 (c) is a scanning electron microscope image of Fe-CQD@Zn-PC-2.

[0023] Figure 2 This is a transmission electron microscope (TEM) image of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention. Figure 2 (a) is a transmission electron microscope image of Fe-CQD@Zn-PC-2 at a magnification of 150,000x. Figure 2(b) is a transmission electron microscope (TEM) image of Fe-CQD@Zn-PC-2 at a magnification of 600,000x, i.e. Figure 2 (a) Magnified transmission electron microscope image of the area within the dashed box.

[0024] Figure 3 The energy dispersive spectrum of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention is shown below. Figure 3 (a) is the original transmission electron microscope image corresponding to the energy-dispersive spectrum, magnified 80,000 times. Figure 3 (b) is the energy dispersive spectrum of C element contained in Fe-CQD@Zn-PC-2. Figure 3 (c) is the energy dispersive spectrum of N element contained in Fe-CQD@Zn-PC-2. Figure 3 (d) is the energy dispersive spectrum of O element contained in Fe-CQD@Zn-PC-2. Figure 3 (e) is the energy dispersive spectrum of Fe element contained in Fe-CQD@Zn-PC-2. Figure 3 (f) is the energy dispersive spectrum of Zn contained in Fe-CQD@Zn-PC-2.

[0025] Figure 4 X-ray diffraction patterns of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of the present invention, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2.

[0026] Figure 5 Infrared absorption spectra of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of the present invention, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2.

[0027] Figure 6 The image shows the electron paramagnetic resonance spectrum of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention; wherein, Figure 6 (a) is the electron paramagnetic resonance spectrum of the TEMP-¹O2 signal peak. Figure 6 (b) DMPO–O2 •− Electron paramagnetic resonance spectrum of the signal peak.

[0028] Figure 7The graph shows the removal effect of Fe-CQD@Zn-PC-1, Fe-CQD@Zn-PC-2, Fe-CQD@Zn-PC-3, Fe-CQD@Zn-PC-4, Fe-CQD@PC, PC and the blank group on oxytetracycline wastewater in Example 5 of the present invention.

[0029] Figure 8 The image shows the removal effect of Fe-CQD@Zn-PC-2 on oxytetracycline wastewater with different pH values ​​(pH values ​​of 3, 5, 7, 9, and 11) in Example 6 of this invention.

[0030] Figure 9 The image shows the removal effect of Fe-CQD@Zn-PC-2 on oxytetracycline wastewater of different concentrations (10 mg / L, 30 mg / L, 50 mg / L, 70 mg / L, and 90 mg / L, respectively) in Example 7 of this invention.

[0031] Figure 10 The graph shows the removal effect of Fe-CQD@Zn-PC-2 on oxytetracycline wastewater in five experiments in Example 8 of this invention. Detailed Implementation

[0032] 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. All materials and instruments used in the following embodiments are commercially available. Unless otherwise specified, the data obtained in the following embodiments are the average values ​​of three or more repeated experiments.

[0033] Example 1 A method for preparing an iron-modified carbon quantum dot-embedded zinc-doped porous carbon material according to the present invention includes the following steps: S1. Disperse polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine in anhydrous ethanol, stir at 300 r / min for 30 min, and then sonicate for 20 min to obtain a precursor solution; wherein, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:1.351:0.8, and the mass-volume ratio of polyethylene terephthalate to anhydrous ethanol is 1 g:50 mL. In this embodiment, 0.005 mol (1.351 g) of ferric chloride hexahydrate was used.

[0034] S2. Add the precursor solution obtained in step S1 to the reaction vessel and perform a solvothermal reaction at 180℃ for 8 hours. After the reaction, allow the reaction vessel to cool naturally, open it, and collect the crude product solution. Centrifuge the obtained solution at 8500 r / min for 30 minutes, then take 25 mL of the supernatant and dialyze it with ultrapure water for two days, changing the water every 12 hours. Use a 1000 Da dialysis bag for dialysis. Filter the dialyzed solution through a 0.22 μm filter membrane, and dilute the filtrate to 100 mL in a 100 mL volumetric flask to obtain an iron-modified carbon quantum dot solution.

[0035] S3. The iron-modified carbon quantum dot solution obtained in step S2 is mixed with polyethylene terephthalate and stirred at 300 r / min for 1 h, then sonicated for 1 h, and then centrifuged at 4000 r / min for 5 min. After washing with water and anhydrous ethanol three times each, a mixed precipitate is obtained. Anhydrous ethanol solution of zinc chloride is added dropwise to the mixed precipitate, stirred, and dried at 60 °C for 2 h to obtain a precursor mixture. The mass ratio of polyethylene terephthalate, zinc chloride and polyethylene terephthalate in step S3 to that in step S1 is 1:0.682:1. The anhydrous ethanol solution of zinc chloride is prepared by dissolving zinc chloride in anhydrous ethanol. The mass concentration of zinc chloride in the anhydrous ethanol solution of zinc chloride is 0.068 g / mL.

[0036] S4. The precursor mixture obtained in step S3 is placed in a tube furnace and calcined at 700°C for 2 hours under N2 atmosphere at a heating rate of 5°C / min. The resulting product is first washed three times each with pure water and 1 mol / L H2SO4 solution, and then vacuum dried at 60°C for 12 hours to obtain iron-modified carbon quantum dot embedded zinc-doped porous carbon material, denoted as Fe-CQD@Zn-PC-1.

[0037] The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-1) prepared in this embodiment comprises iron-modified carbon quantum dots and zinc-doped porous carbon. The iron-modified carbon quantum dots are embedded in the zinc-doped porous carbon, and a small amount of nitrogen is also doped into the iron-modified carbon quantum dots. BET analysis shows that the specific surface area of ​​the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-1) is 434.57 m². 2 / g.

[0038] Example 2 A method for preparing iron-modified carbon quantum dot-embedded zinc-doped porous carbon material according to the present invention is basically the same as that in Example 1, except that: in step S1, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:2.703:0.8, and 0.01 mol of ferric chloride hexahydrate is used. The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material obtained is denoted as Fe-CQD@Zn-PC-2.

[0039] Example 3 A method for preparing iron-modified carbon quantum dot-embedded zinc-doped porous carbon material according to the present invention is basically the same as that in Example 1, except that: in step S1, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:4.054:0.8, and 0.015 mol of ferric chloride hexahydrate is used. The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material obtained is denoted as Fe-CQD@Zn-PC-3.

[0040] Example 4 A method for preparing iron-modified carbon quantum dot-embedded zinc-doped porous carbon material according to the present invention is basically the same as that in Example 1, except that: in step S1, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:5.406:0.8, and 0.02 mol of ferric chloride hexahydrate is used. The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material obtained is denoted as Fe-CQD@Zn-PC-4.

[0041] Comparative Example 1 A method for preparing an iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) is basically the same as the preparation process of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) in Example 2, except that: in this comparative example, step S3 involves mixing the iron-modified carbon quantum dot solution obtained in step S2 with polyethylene terephthalate, stirring at 300 r / min for 1 h, then sonicating for 1 h, centrifuging at 4000 r / min for 5 min, washing with water and anhydrous ethanol three times each to obtain a mixed precipitate, and drying at 60 °C for 2 h to obtain a precursor mixture. The mass ratio of polyethylene terephthalate in step S3 to polyethylene terephthalate in step S1 is 1:1. The final iron-modified carbon quantum dot-doped porous carbon material is denoted as Fe-CQD@PC.

[0042] Comparative Example 2 A method for preparing porous carbon material (PC) includes the following steps: placing polyethylene terephthalate in a tube furnace and calcining it at 700°C for 2 hours under N2 atmosphere at a heating rate of 5°C / min; washing the obtained product three times each with pure water and 1 mol / L H2SO4 solution; and then drying it under vacuum at 60°C for 12 hours to obtain porous carbon material, denoted as PC.

[0043] Characterization and Analysis: Figure 1 The images show scanning electron microscope (SEM) images of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2. Figure 1 (a) represents PC. Figure 1 (b) is Fe-CQD@PC, Figure 1 (c) is Fe-CQD@Zn-PC-2. (From...) Figure 1 (a) Figure 1 (b) Figure 1 (c) It can be seen that PC exhibits a blocky carbon structure with partial layered exfoliation. After the addition of Fe-CQD, Fe-CQD@PC exhibits a rougher surface with irregular wrinkles and particulate deposits. Compared with Fe-CQD@PC, Fe-CQD@Zn-PC-2 with the introduction of zinc exhibits a loose three-dimensional porous network with abundant interconnected pores and wrinkled nanosheets, forming a hierarchical porous structure. It is evident that the introduction of zinc may promote pore formation during pyrolysis through its volatilization and activation effects, transforming the dense carbon skeleton into a sponge-like porous structure.

[0044] Figure 2 This is a transmission electron microscope (TEM) image of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention. Figure 2 (a) Figure 2 (b) Transmission electron microscopy (TEM) images of Fe-CQD@Zn-PC-2 at different magnifications. For example... Figure 2 As shown in (a), the carbon matrix exhibits a thin, wrinkled, sheet-like structure embedded with dark particles, as further magnified... Figure 2 As shown in (b), a large number of ultra-small nanoparticles with a particle size of about 4-6 nm are uniformly dispersed in the carbon matrix. Based on subsequent energy dispersive spectroscopy measurements, it can be inferred that they are ZnO and Fe-CQD.

[0045] Figure 3The energy dispersive spectrum of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention is shown below. Figure 3 (a) is the original transmission electron microscope image corresponding to the energy-dispersive spectrum. Figure 3 (b) to Figure 3 (f) is the energy dispersive spectrum of the elements contained in Fe-CQD@Zn-PC-2. Figure 3 The results show that O and Zn elements are mainly enriched in the larger particle regions, while Fe elements are uniformly distributed throughout the carbon matrix without obvious agglomeration. A small amount of N elements is doped into the material, which can effectively promote the adsorption and activation of PMS. Based on the elemental distribution characteristics and the material synthesis conditions, it can be inferred that the larger particles are likely ZnO, while the ultrasmall nanoparticles can be classified as Fe-CQDs, indicating that they may have formed in situ during carbonization. The uniform dispersion of Fe elements and the coexistence of the two types of particles are consistent with the expected composite structure.

[0046] Figure 4 X-ray diffraction patterns of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2. Figure 4 As shown, all three samples exhibited distinct amorphous carbon characteristic diffraction peaks at 2θ≈22°, indicating that the introduction of metal species did not significantly disrupt the low crystallinity structure of the carbon substrate. Compared to the XRD pattern of PC, Fe-CQD@PC showed only weak and broad bulging peaks in the 2θ range of 30°–45°, which may be due to the relatively low Fe-CQD content and the fact that Fe species were loaded onto the carbon substrate in a highly dispersed, low-crystallinity form. In contrast, Fe-CQD@Zn-PC-2 exhibited distinct characteristic peaks in the 2θ range of 30°–80°, which were consistent with the characteristic diffraction pattern of zinc oxide, proving that zinc had been successfully loaded onto the catalyst.

[0047] Figure 5 The infrared absorption spectra of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2, the iron-modified carbon quantum dot-doped porous carbon material (Fe-CQD@PC) prepared in Comparative Example 1, and the porous carbon material (PC) prepared in Comparative Example 2 are shown below. Figure 5 It can be seen that the FT-IR spectrum at 3450 cm⁻¹ -1 1629cm -1 and 1165cm -1 A distinct characteristic absorption band is observed at 3450 cm⁻¹.-1 The strong and broad absorption band at this location is attributed to the stretching vibrations of the O–H groups on the material surface. Notably, the intensity of this absorption band in Fe-CQD@Zn-PC-2 is higher than that in PC and Fe-CQD@PC, indicating an increased specific surface area of ​​the sample. (1629 cm⁻¹) -1 The absorption band at 1165 cm⁻¹ corresponds to the contributions of aromatic C=C framework vibrations and some C=O carbonyl vibrations in the carbon material, confirming the structural integrity of the carbon framework. -1 The absorption band at the point is attributed to the superposition vibration of C–O bond and Fe–O / Zn–O metal-oxygen bond. The absorption intensity order is Fe-CQD@Zn-PC-2>Fe-CQD@PC>PC, indicating that the Fe and Zn active components are successfully loaded onto the carbon substrate through chemical bonding.

[0048] Figure 6 The image shows the electron paramagnetic resonance (EPR) spectrum of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention. Figure 6 (a) is the TEMP-¹O2 signal peak. Figure 6 (b) is DMPO–O2 •- Signal peaks were measured at 0 min, 1 min, and 5 min after adding the trapping agent and mixing. Electron paramagnetic resonance (EPR) was used to identify active species in the Fe-CQD@Zn-PC-2 / PMS system, among which DMPO (5,5-dimethyl-1-pyrrolline-N-oxide) was used to capture O2. •- TEMP (2,2,6,6-tetramethylpiperidine) is used for capture 1 O2, after adding TEMP, in Figure 6 (a) shows a clear characteristic signal of the TEMP–¹O2 adduct, indicating that it was generated during PMS activation. 1 O2. For example... Figure 6 As shown in (b), only a very weak DMPO–O2 attributable to DMPO was detected after the addition of DMPO. •- The fourfold characteristic signal of the adduct indicates that only a small amount of O2 is generated in the Fe-CQD@Zn-PC-2 / PMS system. •- The above analysis shows that in the Fe-CQD@Zn-PC / PMS system, the free radical pathway (O2) •- ) and non-radical pathways ( 1 O2) coexists, and the active species produced by catalysis are... 1 O2 is the main component.

[0049] Example 5 The porous carbon materials (hereinafter referred to as adsorption catalysts) prepared in Examples 1-4, Comparative Example 1, and Comparative Example 2 were used to treat antibiotic wastewater. Specifically, the iron-modified carbon quantum dot-embedded zinc-doped porous carbon materials prepared in Examples 1-4, the iron-modified carbon quantum dot-doped porous carbon materials prepared in Comparative Example 1, and the porous carbon materials prepared in Comparative Example 2 were used to catalyze the degradation of oxytetracycline (OTC) wastewater, including the following steps:

[0050] 20 mg of adsorption catalyst was added to 100 mL of oxytetracycline wastewater with a concentration of 20 mg / L and a pH of 6. The mixture was shaken at 180 r / min for 30 min until adsorption equilibrium was reached. Then, 30 mg of potassium peroxymonosulfate complex salt (2 KHSO5·KHSO4·K2SO4) was added, with a potassium peroxymonosulfate (PMS) content of 46%. The mixture was shaken at 180 r / min for another 30 min to carry out an advanced oxidation reaction and achieve the treatment of oxytetracycline.

[0051] During the shaking process, 4 mL of sample was taken every 10 minutes (i.e., at 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min after the addition of the adsorption catalyst). The sample was centrifuged, and the absorbance of the supernatant was measured using a UV-Vis spectrophotometer to determine the concentration of oxytetracycline after degradation. This determined the catalytic degradation effect of the adsorption catalyst on oxytetracycline. The blank group consisted of no adsorption catalyst added, with all other steps performed identically. The results are as follows: Figure 7 As shown.

[0052] Figure 7 The images show the removal effects of iron-modified carbon quantum dot-embedded zinc-doped porous carbon materials from Examples 1-4 of this invention, the iron-modified carbon quantum dot-doped porous carbon material from Comparative Example 1, and the porous carbon material from Comparative Example 2 on oxytetracycline wastewater. Figure 7 It can be seen that the removal rates of oxytetracycline after 1 h of reaction for Fe-CQD@Zn-PC-1, Fe-CQD@Zn-PC-2, Fe-CQD@Zn-PC-3, Fe-CQD@Zn-PC-4, Fe-CQD@PC, PC, and the blank group were 91.31%, 92.70%, 91.29%, 90.21%, 71.30%, 65.10%, and 56.80%, respectively. This shows that the iron-modified carbon quantum dot embedded zinc-doped porous carbon material of the present invention can greatly enhance the catalytic degradation effect of oxytetracycline, and the iron-modified carbon quantum dot embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) has the best catalytic effect.

[0053] Example 6 An application of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of the present invention in the treatment of antibiotic wastewater includes the following steps: Five portions of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2, each 20 mg, were weighed and added to oxytetracycline wastewater with pH values ​​of 3, 5, 7, 9, and 11, respectively. The volume of each oxytetracycline wastewater was 100 mL and the concentration was 20 mg / L. The mixture was shaken at 180 r / min for 30 min until adsorption equilibrium was reached. Then, 30 mg of potassium peroxymonosulfate composite salt was added. The potassium peroxymonosulfate content in the potassium peroxymonosulfate composite salt was 46%. The mixture was shaken at 180 r / min for another 30 min to carry out an advanced oxidation reaction, thereby treating the oxytetracycline.

[0054] During the oscillation process, 4 mL samples were taken every 10 minutes (i.e., at 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min after catalyst addition) and centrifuged. The absorbance of the supernatant obtained after centrifugation was measured using a UV-Vis spectrophotometer to determine the concentration of oxytetracycline after adsorption. This yielded the catalytic degradation effect of iron-modified carbon quantum dots embedded with zinc-doped porous carbon materials on oxytetracycline wastewater at different pH values. The results are as follows: Figure 8 As shown.

[0055] Figure 8 The figure shows the removal effect of the iron-modified carbon quantum dot embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention on oxytetracycline wastewater at different pH values. As can be seen from the figure, Fe-CQD@Zn-PC-2 exhibits good removal effects in acidic, alkaline and neutral environments. The removal effect is the highest at pH 11, reaching 90.76%. This may be due to the following reasons: (1) Under acidic conditions, the protonation of functional groups on the catalyst surface enhances the adsorption of OTC and promotes the activation of PMS, thereby improving the pollutant removal efficiency; (2) Under neutral conditions, the abundant active sites provided by Fe-CQD and Zn-regulated carbon structure can stabilize with PMS, maintaining high degradation performance of the system; (3) In alkaline environments, PMS may partially decompose, generating SO5. •- It may further participate in the reaction formation. 1 O2. In summary, the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of the present invention exhibits good catalytic degradation effect on oxytetracycline under different pH conditions.

[0056] Example 7 An application of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of the present invention in the treatment of antibiotic wastewater includes the following steps: Five portions (20 mg each) of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 were weighed and added to oxytetracycline wastewater at concentrations of 10 mg / L, 30 mg / L, 50 mg / L, 70 mg / L, and 90 mg / L, respectively. The volume of each oxytetracycline wastewater was 100 mL and the pH value was 6. The mixture was shaken at 180 r / min for 30 min until adsorption equilibrium was reached. Then, 30 mg of potassium peroxymonosulfate composite salt was added. The potassium peroxymonosulfate content in the potassium peroxymonosulfate composite salt was 46%. The mixture was shaken at 180 r / min for another 30 min to carry out an advanced oxidation reaction, thereby treating the oxytetracycline.

[0057] During the oscillation process, 4 mL samples were taken every 10 minutes (i.e., at 0 min, 10 min, 20 min, 30 min, 40 min, 50 min, and 60 min after catalyst addition) and centrifuged. The absorbance of the supernatant obtained after centrifugation was measured using a UV-Vis spectrophotometer to determine the concentration of oxytetracycline after adsorption. This yielded the adsorption effect of iron-modified carbon quantum dots embedded with zinc-doped porous carbon materials on wastewater of different concentrations of oxytetracycline. The results are as follows: Figure 9 As shown.

[0058] Figure 9 The image shows the removal effect of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 of this invention on wastewater containing different concentrations of oxytetracycline. Figure 9 It was found that when the oxytetracycline wastewater concentrations were 10 mg / L, 30 mg / L, 50 mg / L, 70 mg / L, and 90 mg / L, the removal rates of oxytetracycline by Fe-CQD@Zn-PC-2 were 94.31%, 81.15%, 72.91%, 70.39%, and 67.57%, respectively. This indicates that the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of this invention exhibits good catalytic effects on oxytetracycline wastewater of different concentrations, with better removal effects on low-concentration oxytetracycline wastewater. This is because as the oxytetracycline concentration increases, the free radicals generated by catalysis are insufficient to effectively degrade all pollutants, thus reducing the removal efficiency to some extent. Furthermore, higher oxytetracycline concentrations may lead to the accumulation of intermediate byproducts, which can competitively consume active species or inhibit the degradation process, further resulting in a decrease in catalytic performance.

[0059] Example 8 An application of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of the present invention in the treatment of antibiotic wastewater includes the following steps:

[0060] (1) Weigh 20 mg of the iron-modified carbon quantum dot embedded zinc-doped porous carbon material (Fe-CQD@Zn-PC-2) prepared in Example 2 and add it to 100 mL of oxytetracycline wastewater with a concentration of 20 mg / L. The pH value of the oxytetracycline wastewater is 6. Shake for 30 min at a speed of 180 r / min. Add 30 mg of potassium persulfate composite salt. The potassium persulfate content in the potassium persulfate composite salt is 46%. Continue to shake for 30 min at 180 r / min to carry out advanced oxidation reaction and achieve the treatment of oxytetracycline. Take 4 mL of sample after treatment.

[0061] (2) The above-treated oxytetracycline adsorption catalyst was washed three times with pure water and three times with anhydrous ethanol, and then vacuum dried at 60°C for 12 hours. The obtained Fe-CQD@Zn-PC-2 was added to the oxytetracycline wastewater. The process of step (1) was repeated, and 4 mL of sample was taken.

[0062] (3) Repeat step (2) three times, taking 4 mL of sample each time.

[0063] The samples were centrifuged, and the absorbance of the supernatant was measured using a UV-Vis spectrophotometer to determine the concentration of oxytetracycline after degradation. This allowed for the determination of the catalytic degradation effect of iron-modified carbon quantum dot-embedded zinc-doped porous carbon material on oxytetracycline wastewater after different cycles. The results are as follows: Figure 10 As shown. By Figure 10 The removal rates in the five experiments were 92.80%, 91.88%, 89.26%, 87.94%, and 85.43%, respectively. After multiple consecutive cycles, the removal rate of oxytetracycline remained above 85%, indicating that the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material of this invention has excellent cycle stability, confirming its good structural and performance durability during potassium persulfate activation.

[0064] As described above, the iron-modified carbon quantum dots embedded in zinc-doped porous carbon materials prepared in this invention are applied to the treatment of antibiotic wastewater. This is achieved by mixing the iron-modified carbon quantum dots embedded in the zinc-doped porous carbon material with the antibiotic wastewater, followed by agitation and the addition of potassium persulfate, resulting in highly efficient degradation of antibiotics. This method is not only simple in its process and equipment, easy to operate, and low in cost, but also highly efficient, with good catalytic effect, high reusability, and cleanliness. It is a widely applicable and highly efficient method for removing antibiotics, possessing significant application and commercial value.

[0065] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the spirit and technical essence of the present invention. Therefore, any simple modifications, equivalent substitutions, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A method for preparing an iron-modified carbon quantum dot embedded zinc-doped porous carbon material, characterized in that, Includes the following steps: S1. Polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine are dispersed in anhydrous ethanol, and after stirring and sonication, a precursor solution is obtained. S2. The precursor solution is subjected to a solvothermal reaction at 180℃~200℃. After the reaction, the solution is centrifuged, dialyzed and filtered to obtain an iron-modified carbon quantum dot solution. S3. The iron-modified carbon quantum dot solution is mixed with polyethylene terephthalate, and after the first stirring and sonication, it is centrifuged and washed to obtain a mixed precipitate. Anhydrous ethanol solution of zinc chloride is added dropwise to the obtained mixed precipitate, and after the second stirring and drying, a precursor mixture is obtained. S4. The precursor mixture is calcined at 600℃~700℃ under N2 atmosphere. The resulting product is washed and dried to obtain iron-modified carbon quantum dot embedded zinc-doped porous carbon material.

2. The method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to claim 1, characterized in that, In step S1, the mass ratio of polyethylene terephthalate, ferric chloride hexahydrate, and triethanolamine is 1:1.351-5.406:0.8-1, and the mass-volume ratio of polyethylene terephthalate to anhydrous ethanol is 1g:50mL-100mL.

3. The method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to claim 1, characterized in that, The mass ratio of polyethylene terephthalate and zinc chloride in step S3 to that in step S1 is 1:0.682 to 1.364:1, and the mass concentration of zinc chloride in the anhydrous ethanol solution of zinc chloride is 0.068 g / mL to 0.136 g / mL.

4. The method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to any one of claims 1 to 3, characterized in that, In step S1, the stirring speed is 300 r / min to 400 r / min, the stirring time is 20 min to 30 min, and the ultrasonication time is 20 min to 30 min; In step S2, the solvothermal reaction time is 8h to 12h, the centrifugation speed is 8500r / min to 10000r / min, the centrifugation time is 20min to 30min, the dialysis uses a 1000Da dialysis bag, the dialysis solution is water, the dialysis time is 2d to 3d, and the dialysis solution is changed every 8h to 12h.

5. The method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to any one of claims 1 to 3, characterized in that, In step S3, the first stirring speed is 300 r / min to 400 r / min, the first stirring time is 0.5 h to 1 h, the ultrasonic time is 0.5 h to 1 h, the centrifugation speed is 4000 r / min to 5000 r / min, the centrifugation time is 5 min to 10 min, the washing refers to washing with water and anhydrous ethanol in sequence, the number of times the water is washed is 2 to 3 times, the number of times the anhydrous ethanol is washed is 2 to 3 times, the drying temperature is 60℃ to 80℃, and the drying time is 1 h to 2 h.

6. The method for preparing iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to any one of claims 1 to 3, characterized in that, In step S4, the heating rate is 5℃ / min to 10℃ / min, the calcination time is 2h to 3h, the washing refers to washing with water and H2SO4 solution sequentially, the number of times the water is washed is 2 to 3 times, the number of times the H2SO4 solution is washed is 2 to 3 times, the concentration of the H2SO4 solution is 1mol / L to 2mol / L, the drying is vacuum drying, the temperature of the vacuum drying is 60℃ to 80℃, and the time of the vacuum drying is 8h to 12h.

7. The iron-modified carbon quantum dot-embedded zinc-doped porous carbon material prepared by the preparation method of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material as described in any one of claims 1 to 6.

8. The iron-modified carbon quantum dot embedded zinc-doped porous carbon material according to claim 7, characterized in that, The iron-modified carbon quantum dot embedded zinc-doped porous carbon material comprises iron-modified carbon quantum dots and zinc-doped porous carbon, wherein the iron-modified carbon quantum dots are embedded in the zinc-doped porous carbon.

9. The application of an iron-modified carbon quantum dot-embedded zinc-doped porous carbon material prepared by any one of claims 1 to 6, or the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material as described in claim 7 or 8, in the treatment of antibiotic wastewater.

10. The application according to claim 9, characterized in that, The application includes the following steps: embedding the iron-modified carbon quantum dots into zinc-doped porous carbon material and adding it to antibiotic wastewater, shaking until adsorption equilibrium is reached, then adding an oxidant, and continuing to shake to carry out an advanced oxidation reaction to achieve the treatment of antibiotic wastewater; The mass-to-volume ratio of the iron-modified carbon quantum dot-embedded zinc-doped porous carbon material to the antibiotic wastewater is 0.2g-0.3g:1L. The concentration of the antibiotic wastewater is 10mg / L-20mg / L, the pH value of the antibiotic wastewater is 3-11, the antibiotic wastewater is oxytetracycline wastewater, the oscillation speed is 150r / min-200r / min, the oscillation time is 30min-60min, the oscillation speed is 150r / min-200r / min, the oscillation time is 30min-60min, the oscillation continues at 150r / min-200r / min for 30min-60min, the oxidant is potassium peroxymonosulfate complex salt, the potassium peroxymonosulfate content in the potassium peroxymonosulfate complex salt is 46%, and the addition concentration of the potassium peroxymonosulfate complex salt is 0.2g / L-0.3g / L.

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