Cqd-mof stabilized polysulfone hollow porous microspheres, preparation and application thereof

Abstract

The application belongs to the technical field of material chemistry and water treatment, and provides a CQD-MOF stable polysulfone hollow porous microsphere and preparation and application thereof. The CQD@UiO-66-NH2 is prepared by condensation synthesis, then the polysulfone and PVP are dissolved, CQD@UiO-66-NH2 is added and mixed, and then a coagulation bath is carried out to form CQD@UiO-66-NH2 / PSF composite hollow microspheres. The composite hollow microspheres not only have the inherent high specific surface area and a large number of active sites of UiO-66-NH2, but also show the advantageous properties of excellent photocatalytic capacity and low-density recyclable characteristics of CQD, and have excellent degradation efficiency on tetracycline and methylene blue, and have good industrial application prospect.

Description

Technical Field

[0001] This invention belongs to the fields of materials chemistry and water treatment technology, specifically relating to the preparation of polysulfone microspheres stabilized by nanoparticles and their application in photocatalytic degradation of organic pollutants. Background Technology

[0002] The information disclosed in this background section is intended to enhance understanding of the overall background of the present invention.

[0003] The widespread use of organic pollutants, particularly organic dyes and antibiotics such as methylene blue and tetracycline, has led to a continuous increase in their prevalence in aquatic systems, causing serious environmental damage. These organic dyes and antibiotics are characterized by exogenous bases and complex aromatic configurations, making them highly stable under light, difficult to degrade, and requiring oxidation for degradation. Previous academic research has demonstrated that traditional water treatment methods, including adsorption, membrane filtration, chemical flocculation, ion exchange, and microwave catalysis, encounter inherent limitations in removing these organic pollutants. Therefore, developing effective, eco-friendly, and sustainable water treatment technologies is crucial.

[0004] Photocatalysis, hailed as a promising water treatment method, has attracted increasing attention from the academic community in recent years. This technology differs from traditional water purification strategies due to its rapid reaction kinetics, eliminating the need for chemical reagents and avoiding the generation of secondary wastewater. Simultaneously, to enhance the efficiency of the photocatalytic process, researchers are constantly seeking innovation and combining novel photocatalytic materials to enhance its photoreactivity. Against this backdrop, metal-organic frameworks (MOFs) have attracted considerable interest due to their large specific surface area, abundant active sites, and modifiable pore structure. UiO-66-NH2, an amino-functionalized MOF, not only exhibits excellent stability but also provides an optimal adsorption environment for organic pollutants due to its porous structure. UiO-66-NH2 can serve as a photocatalyst capable of generating reactive oxygen species (ROS); however, the lack of active sites, the rapid recombination of photogenerated charges, and poor visible light absorption remain obstacles to its catalytic activity.

[0005] The carbonaceous and hydrophilic properties of carbon quantum dots (CQDs) significantly enhance photocatalytic efficiency by absorbing visible light and suppressing the recombination of photogenerated electron / hole pairs. Composites of MOFs and quantum dots (QDs) exhibit even higher photocatalytic activity. QD-MOF composites have applications in various fields, including compound synthesis and pollutant degradation, such as water splitting for hydrogen production, carbon dioxide (CO2) reduction to methane (CH4), organic dye degradation, Cr(VI) reduction and oxidation, and comprehensive treatment of nitric oxide (NO). However, most carbon quantum dot-modified MOF composites are prepared in powder form, and how to better recycle and utilize them is a problem that needs to be solved. Summary of the Invention

[0006] To address the problems of poor photocatalytic degradation of organic pollutants by metal-organic frameworks (MOFs), difficulty in recycling, and easy secondary pollution, this invention provides a method for preparing polysulfone hollow porous microspheres stabilized by MOF nanoparticles modified with carbon quantum dots. This method effectively enhances the photocatalytic performance of UiO-66-NH2, and the microspheres are stable and easy to recycle, eliminating the need for chemical reagents and avoiding the generation of secondary wastewater.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] A method for preparing polysulfone hollow porous microspheres stabilized by carbon quantum dot-modified MOF nanoparticles includes the following steps: (1) ZrCl4 and 2-aminoterephthalic acid (NH2-BDC) were added to N,N-dimethylformamide (DMF) and dispersed evenly. Then, an organic weak acid was added to pH 3-4, and after mixing, a hydrothermal reaction was carried out. The product was separated and purified to obtain UiO-66-NH2. (2) Dissolve citric acid and ethylenediamine in water, heat to react, and separate the product by dialysis to obtain functionalized CQD; (3) Functionalized CQD and UiO-66-NH2 aqueous solution were mixed and reacted in the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS). The reaction solution was separated and purified to obtain CQD@UiO-66-NH2. (4) Polysulfone (PSF) and polyvinylpyrrolidone (PVP) are added to N-methylpyrrolidone (NMP) and dichloromethane (DCM) in a volume ratio of 1:5 to obtain a mixture; then CQD@UiO-66-NH2 is added and mixed, and then placed in a coagulation bath to form CQD@UiO-66-NH2 / PSF composite hollow microspheres. The microspheres are filtered, washed and dried to obtain CQD@UiO-66-NH2 / PSF.

[0009] In step (1), the molar ratio of ZrCl4 to 2-aminoterephthalic acid is 1:1 to 1:3, preferably 1:1. The added mass of N,N-dimethylformamide is 5 to 10 times the sum of the masses of ZrCl4 and 2-aminoterephthalic acid, preferably 8 to 10 times. The organic weak acid is selected from formic acid or acetic acid.

[0010] In step (1), the temperature of the hydrothermal reaction is 120℃-150℃; the reaction time is 20-26 hours.

[0011] In step (2), the mass ratio of citric acid to ethylenediamine is 1:1-3:1; preferably 2:1.

[0012] In step (2), the reaction temperature is 150℃-170℃ and the reaction time is 5-8 hours.

[0013] In step (2), the molecular weight cutoff for dialysis is 500-2000; such as 500, 800, 1000, 1200, 1500, 2000 or any value between the above.

[0014] In step (1) or (3), the separation and purification are carried out by solvent washing and centrifugation of the precipitate; the washing solvent can be DMF, anhydrous ethanol or water; the centrifugation speed is 6000 rpm-12000 rpm and the time is 5-10 min.

[0015] In step (3), the mass ratio of CQD to UiO-66-NH2 is 1:500-1:50; preferably 1:100. The amounts of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) are 0.1 wt%-0.3 wt% and 0.2 wt%-0.5 wt% of UiO-66-NH2, respectively; preferably 0.1 wt% and 0.3 wt%.

[0016] In step (4), the mass ratio of CQD@UiO-66-NH2 to PSF is 0.08:1-0.88:1; preferably 0.1:1-0.88:1; more preferably 0.4:1-0.8:1.

[0017] In step (4), the content of PSF in the mixture is 1 wt%-5 wt%; the content of PVP in the mixture is 0.5 wt%-5 wt%.

[0018] PVP can form a uniform film in an NMP / DCM mixed solution, serving as a template for polysulfone and CQD@UiO-66-NH2 in the coagulation bath. During the polymerization of polysulfone in the coagulation bath, it grows on the PVP film, forming hollow microspheres. Therefore, PVP of any molecular weight can be used as a template. Selection can be made based on the intended use of the final product. For example, using PVP K30 yields better microsphere morphology and dispersibility, using PVP K60 yields more stable microspheres, and using PVP K90 yields microspheres with higher permeability.

[0019] In step (4), the coagulation bath is a 1 wt%-2 wt% aqueous solution of polyvinyl alcohol.

[0020] A type of polysulfone hollow porous microsphere obtained by the above preparation method has a hollow center and densely packed small pores on its wall.

[0021] The porosity of the aforementioned microspheres is over 50%, and the total pore area is 50-60 m².2 / g, with an average diameter of 10 μm-30 μm for the hollow center, an average pore size of 80-150 nm for the pores in the sphere wall, a packing density not exceeding 0.6 g / mL, and an apparent density of 0.8 g / mL-1.2 g / mL.

[0022] The aforementioned polysulfone hollow porous microspheres can be used for the degradation of organic pollutants.

[0023] The present invention also provides a method for removing contaminants using the above-mentioned polysulfone hollow porous microspheres, comprising the following steps: Organic pollutants are contacted with polysulfone hollow porous microspheres under dark or light conditions.

[0024] The organic pollutant is an organic dye or antibiotic; preferably, the organic pollutant is methylene blue or tetracycline.

[0025] The present invention has the following advantages: The preparation method of this invention covalently links the amino group of UiO-66-NH2 with the carboxyl group of CQD, thereby functionalizing UiO-66-NH2 and CQD. By applying the Pickering emulsion template method, a polysulfone (PSF) emulsion stabilized by CQD@UiO-66-NH2 is prepared, thus creating a novel composite porous hollow microsphere encapsulated and stabilized by CQD-modified MOF composite nanoparticles. The N-methylpyrrolidone (NMP) and dichloromethane (DCM) in the Pickering emulsion with CQD-MOF as a stabilizer are evaporated to obtain the final CQD@UiO-66-NH2 / PSF composite solid microspheres. These innovative composite hollow microspheres not only possess the inherent high specific surface area and numerous active sites of UiO-66-NH2, but also exhibit excellent photocatalytic activity and the advantageous properties of CQD's low density and recyclability. Furthermore, they demonstrate excellent degradation efficiency for tetracycline and methylene blue, showing promising prospects for industrial application. Attached Figure Description

[0026] Figure 1 These are scanning electron microscope (SEM) images of the CQD@UiO-66-NH2 / PSF composite microspheres in Example 1 and the PSF microspheres in Comparative Example 1. Figure 2 It is CQD@UiO-66-NH in Example 1 2 / Adsorption curve of methylene blue (MB) on PSF composite microspheres; Figure 3 This refers to the degradation change of MB (C / CO) over time by the CQD@UiO-66-NH2 / PSF composite microspheres in Example 3. Figure 4It is the kinetic rate constant of the CQD@UiO-66-NH2 / PSF composite microspheres on methylene blue (MB) solution in Example 3; Figure 5 These are fluorescence and appearance images of the CQD@UiO-66-NH2 / PSF composite microspheres in Example 4; Figure 6 The degradation curve of tetracycline by CQD@UiO-66-NH2 / PSF composite microspheres in Example 4; Figure 7 It is the kinetic rate constant for the degradation of tetracycline by CQD@UiO-66-NH2 / PSF composite microspheres in Example 4; Figure 8 The recovery rate of tetracycline after five cycles of degradation by CQD@UiO-66-NH2 / PSF composite microspheres in Example 4; Figure 9 This refers to the adsorption and catalytic degradation efficiency of tetracycline by the CQD@UiO-66-NH2 / PSF composite microspheres after five cycles in Example 4. Detailed Implementation

[0027] The present invention will be further described below with reference to the embodiments and accompanying drawings, but the present invention is not limited to the following embodiments.

[0028] Example 1: Preparation of CQD@UiO-66-NH2 / PSF (1) Preparation of UiO-66-NH2 0.6438 g of ZrCl4 and 0.5108 g of NH2-BDC were added to 50 mL of DMF and sonicated for 15 minutes. Then, 10 mL of glacial acetic acid was added to adjust the pH and the mixture was stirred for 2 hours. The mixture was then transferred to a high-pressure reactor and reacted at 150 °C for 24 hours. The resulting product was then washed with DMF and anhydrous ethanol and dried under vacuum at 100 °C for 12 hours to obtain UiO-66-NH2. (2) Preparation of carbon quantum dots (CQDs) 5 g of citric acid and 2.5 g of ethylenediamine were dissolved in 50 mL of deionized water in a round-bottom flask. The mixture was then stirred and heated to 160 °C for 6 hours. The reaction solution was then cooled to room temperature and dialyzed using a dialysis bag (1500 MWCO) with the water changed every 12 hours for a total of 48 hours. The retentate was then freeze-dried to obtain functionalized CQD. (3) Preparation of CQD@UiO-66-NH2 Functionalized CQD was added to 1000 g of UiO-66-NH2 aqueous solution (1 wt%) at a mass ratio of 1:50 and mixed with magnetic stirring for 24 hours. UiO-66-NH2 was then reacted with functionalized CQD in the presence of 0.01 g N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and 0.03 g N-hydroxysuccinimide (NHS). After the reaction was complete, the reaction solution was centrifuged at 8000 rpm and washed three times with deionized water to remove unreacted raw materials. After drying, CQD@UiO-66-NH2 was obtained. (4) Preparation of CQD@UiO-66-NH2 / PSF 0.125 g of polysulfone (PSF) and 0.1 g of polyvinylpyrrolidone (PVP K90) were dissolved in 6.0 mL of N-methylpyrrolidone / dichloromethane (NMP:DCM=1:5v / v); then 0.11 g of CQD@UiO-66-NH2 was added and stirred for 30 minutes; the mixture was then slowly introduced into a coagulation bath containing 50 mL of 1% polyvinyl alcohol (PVA) aqueous solution through a microchannel to form CQD@UiO-66-NH2 / PSF composite hollow microspheres. After filtration through a 500-mesh filter cloth, the microspheres were washed with ethanol and distilled water respectively, and then filtered again. The filter residue was dried to obtain CQD@UiO-66-NH2 / PSF microspheres.

[0029] Obtain micrographs of microspheres, such as Figure 1 As shown, a densely clustered layer of nanoparticles forms on the surface of the microspheres; a micrograph of the hemispherical cross-section of the microspheres reveals numerous pores permeating their structure; the hollow nature of the microspheres greatly enhances their photocatalytic activity, as it allows reactants and products to flow effectively within the spheres, while providing a large surface area for the adsorption of pollutants. The microspheres exhibit a completely covered textured surface and are hollow and porous, with a total pore area of ​​55.98 m². 2 / g, with a specific surface area of ​​44.98 m². 2 The microspheres have an intermediate pore diameter of 18.95 μm, an average surface pore diameter of 111.07 nm, a bulk density of 0.45 g / mL, an apparent density of 1.04 g / mL, and a porosity of 56.61%.

[0030] Comparative Example 1: Preparation of PSF Microspheres 0.125 g of polysulfone (PSF) and 0.1 g of polyvinylpyrrolidone (PVP K90) were dissolved in 6.0 mL of N-methylpyrrolidone and dichloromethane (NMP:DCM=1:5v / v). The mixture was then slowly introduced through a microchannel into a coagulation bath containing 50 mL of 1% polyvinyl alcohol (PVA) aqueous solution to form PSF composite hollow microspheres. The microspheres were then filtered through a 500-mesh filter cloth and rinsed with ethanol and distilled water, respectively. After filtration again, the filter residue was dried to obtain PSF microspheres.

[0031] Example 2 Adsorption of methylene blue (MB) by CQD@UiO-66-NH2 / PSF microspheres To evaluate the adsorption capacity of CQD@UiO-66-NH2 / PSF microspheres for methylene blue (MB), 10 mg of CQD@UiO-66-NH2 / PSF microspheres were added to 20 mL of a 20 mg / L MB solution. The solution was stirred in the dark at 25°C, and samples were taken at 5-minute intervals. The absorbance at 665 nm was measured using a UV-Vis spectrophotometer for a total of 30 minutes. CQD@UiO-66-NH2 microspheres prepared in Example 1 and PSF microspheres prepared in Comparative Example 1 were used as controls.

[0032] The results are as follows Figure 2 As shown, at a catalyst dosage of 0.5 g / L, adsorption equilibrium for the adsorption and degradation of methylene blue (20 mg / L) was reached within 30 minutes. Compared with CQD@UiO-66-NH2 or PSF alone, the adsorption capacity of CQD@UiO-66-NH2 / PSF microspheres showed a rapid initial increase, followed by stabilization until equilibrium was reached. The porous nature of CQD@UiO-66-NH2 / PSF microspheres and the presence of CQD@UiO-66-NH2 increased the surface area, thereby increasing the adsorption capacity of methylene blue (MB). + The number of potential adsorption sites. Furthermore, positively charged MB... + The electrostatic attraction between the negatively charged PSF material and the microspheres significantly enhanced the adsorption process, resulting in a markedly higher adsorption rate compared to PSF microspheres alone. Because the electrostatic adsorption promoted by the negatively charged PSF material is weaker than that promoted by porous materials such as CQD@UiO-66-NH2, Figure 2 The results show that CQD@UiO-66-NH2 / PSF exhibits excellent adsorption capacity for dye molecules. This enhanced adsorption is due to the increased surface area provided by the inherent porous structure of CQD@UiO-66-NH2 and its associated CQD@UiO-66-NH2 / PSF particles, coupled with the presence of active sites that effectively attract dye molecules.

[0033] Example 3: Preparation of CQD@UiO-66-NH2 / PSF and photocatalytic degradation of methylene blue (1) Preparation of UiO-66-NH2 0.6438 g of ZrCl4 and 0.5108 g of NH2-BDC were added to 50 mL of DMF and sonicated for 15 minutes. Then, 5 mL of formic acid was added to adjust the pH and the mixture was stirred for 2 hours. The mixture was then transferred to a high-pressure reactor and reacted at 130 °C for 24 hours. The resulting product was then washed with DMF and anhydrous ethanol and dried under vacuum at 100 °C for 12 hours to obtain UiO-66-NH2. (2) Preparation of carbon quantum dots (CQDs) 5 g of citric acid and 2.5 g of ethylenediamine were dissolved in 50 mL of deionized water in a round-bottom flask. The mixture was then stirred and heated to 160 °C for 6 hours. The reaction solution was then cooled to room temperature and dialyzed using a dialysis bag (1 K MWCO) with the water changed every 12 hours for a total of 48 hours. The retentate was then freeze-dried to obtain functionalized CQD. (3) Preparation of CQD@UiO-66-NH2 Functionalized CQD was added to 1000 g of UiO-66-NH2 aqueous solution (1 wt%) at a mass ratio of 1:100 and mixed with magnetic stirring for 24 hours. UiO-66-NH2 was then reacted with functionalized CQD in the presence of 0.015 g N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and 0.045 g N-hydroxysuccinimide (NHS). After the reaction was complete, the reaction solution was centrifuged at 10000 rpm and washed three times with deionized water to remove unreacted raw materials. After drying, CQD@UiO-66-NH2 was obtained. (4) Preparation of CQD@UiO-66-NH2 / PSF 0.125 g of polysulfone (PSF) and 0.05 g of polyvinylpyrrolidone (PVP K30) were dissolved in 6.0 mL of N-methylpyrrolidone / dichloromethane (NMP:DCM=1:5v / v); then 0.05 g of CQD@UiO-66-NH2 was added and stirred for 30 minutes; the mixture was then slowly introduced through a microchannel into a coagulation bath containing 50 mL of 2 wt% polyvinyl alcohol (PVA) aqueous solution to form CQD@UiO-66-NH2 / PSF composite hollow microspheres. After filtration through a 500-mesh filter cloth, the microspheres were washed with ethanol and distilled water respectively, and then filtered again. The filter residue was dried to obtain CQD@UiO-66-NH2 / PSF microspheres.

[0034] 10 mg of CQD@UiO-66-NH2 / PSF prepared in this example was added to 20 mL of MB solution (CO = 20 mg / L), and the solution was shaken on a shaker in the dark for 30 min to reach adsorption equilibrium. The suspension was then exposed to ultraviolet light (350W xenon lamp) for photocatalytic degradation. 1.0 mL of the reaction solution was collected every 10 min, centrifuged, and the absorbance at 665 nm was measured using a UV-Vis spectrophotometer. The absorbance was converted to concentration (C0). t ); where C t / C0 refers to the ratio of the concentration of methylene blue at degradation time t to the initial concentration C0. t The smaller the / C0 value, the higher the degradation rate of methylene blue. Therefore, using C... t / C0 was used to characterize the degradation effect of methylene blue, in order to analyze the degradation efficiency of MB by CQD@UiO-66-NH2 / PSF, CQD@UiO-66-NH2 and PSF.

[0035] Figure 3 The degradation change of MB(C / C0) over time was shown, with each material exhibiting a decrease in C / C0, indicating that each material effectively carried out the adsorption and catalytic process. Compared with the individual components CQD@UiO-66-NH2 or PSF, the degradation efficiency of the CQD@UiO-66-NH2 / PSF composite material was enhanced, indicating that the integration of CQD@UiO-66-NH2 enhanced the photocatalytic activity.

[0036] Figure 4 The kinetics of the photocatalytic process were investigated by plotting the natural logarithm of the MB concentration ratio (ln(C / CO)) versus time. The slope of the curve represents the rate constant of the photocatalytic degradation reaction; a steeper slope indicates a faster reaction rate. This kinetic analysis reflects that the reaction rate of the CQD@UiO-66-NH2 / PSF composite material is improved compared to the base material, indicating that the composite hollow microspheres enhance the photocatalytic efficiency. The CQD@UiO-66-NH2 / PSF composite material prepared in this invention has strong application potential in environmental remediation, especially in the photocatalytic treatment of wastewater.

[0037] Example 4: Preparation of CQD@UiO-66-NH2 / PSF (1) Preparation of UiO-66-NH2 0.6438 g of ZrCl4 and 0.5108 g of NH2-BDC were added to 50 mL of DMF and sonicated for 15 minutes. Then, 10 mL of glacial acetic acid was added to adjust the pH and the mixture was stirred for 2 hours. The mixture was then transferred to a high-pressure reactor and reacted at 130 °C for 24 hours. The resulting product was then washed with DMF and anhydrous ethanol and dried under vacuum at 100 °C for 12 hours to obtain UiO-66-NH2. (2) Preparation of carbon quantum dots (CQDs) 5 g of citric acid and 2.5 g of ethylenediamine were dissolved in 50 mL of deionized water in a round-bottom flask. The mixture was then stirred and heated to 160 °C for 6 hours. The reaction solution was then cooled to room temperature and dialyzed using a dialysis bag (1 K MWCO) with the water changed every 12 hours for a total of 48 hours. The retentate was then freeze-dried to obtain functionalized CQD. (3) Preparation of CQD@UiO-66-NH2 Functionalized CQD was added to 1000 g of UiO-66-NH2 aqueous solution (1 wt%) at a mass ratio of 1:500 and mixed with magnetic stirring for 24 hours. UiO-66-NH2 was then reacted with functionalized CQD in the presence of 0.015 g N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and 0.045 g N-hydroxysuccinimide (NHS). After the reaction was complete, the reaction solution was centrifuged at 10000 rpm and washed three times with deionized water to remove unreacted raw materials. After drying, CQD@UiO-66-NH2 was obtained. (4) Preparation of CQD@UiO-66-NH2 / PSF 0.125 g of polysulfone (PSF) and 0.02 g of polyvinylpyrrolidone (PVP K60) were dissolved in 6.0 mL of N-methylpyrrolidone / dichloromethane (NMP:DCM=1:5v / v); then 0.1 g of CQD@UiO-66-NH2 was added and stirred for 30 minutes; the mixture was then slowly introduced through a microchannel into a coagulation bath containing 50 mL of 1.5 wt% polyvinyl alcohol (PVA) aqueous solution to form CQD@UiO-66-NH2 / PSF composite hollow microspheres. After filtration through a 500-mesh filter cloth, the microspheres were washed with ethanol and distilled water respectively, and then filtered again. The filter residue was dried to obtain CQD@UiO-66-NH2 / PSF microspheres.

[0038] The appearance of CQD@UiO-66-NH2 / PSF composite microspheres at different concentrations under ultraviolet (top) and visible (bottom) light are shown in the following figures. Figure 5As shown: Blue fluorescence was observed at the lowest concentration (0.001 g / L), and the fluorescence intensity gradually increased with increasing concentration to the highest concentration (0.1 g / L).

[0039] Comparative Example 2: Preparation of UiO-66-NH2 / PSF UiO-66-NH2 was prepared according to the method in Example 1, and UiO-66-NH2 / PSF was prepared according to the following method: 0.125 g of polysulfone (PSF) and 0.02 g of polyvinylpyrrolidone (PVP K60) were dissolved in 6.0 mL of N-methylpyrrolidone / dichloromethane (NMP:DCM=1:5v / v) mixed solvent; then 0.1 g of UiO-66-NH2 was added and stirred for 30 minutes; then the mixture was slowly introduced into a coagulation bath containing 50 mL of 1% polyvinyl alcohol (PVA) aqueous solution through a microchannel to form UiO-66-NH2 / PSF microspheres, which were then filtered through a 500-mesh filter cloth and washed with ethanol and distilled water respectively, and then filtered again. The obtained filter residue was dried to obtain UiO-66-NH2 / PSF microspheres.

[0040] Example 5: Degradation of tetracycline by CQD@UiO-66-NH2 / PSF 10 mg of CQD@UiO-66-NH2 / PSF (or UiO-66-NH2 / PSF) prepared in Example 4 was added to 20 mL of tetracycline (TC) solution (C0 = 20 mg / L), and the solution was shaken on a shaker in the dark for 30 min to reach adsorption equilibrium. The suspension was then exposed to ultraviolet light (350 W xenon lamp) for photocatalytic degradation. 1.0 mL of the reaction solution was collected every 20 min, centrifuged, and the absorbance at 276 nm was measured using a UV-Vis spectrophotometer. The absorbance was converted to concentration (C0). t ); where C t / C0 refers to the ratio of the concentration of tetracycline at degradation time t to the initial concentration C0. t The smaller the / C0 value, the higher the degradation rate of TC. Therefore, using C... t / C0 was used to characterize the degradation effect of tetracycline, in order to analyze the degradation efficiency of TC by CQD@UiO-66-NH2 / PSF and UiO-66-NH2 / PSF.

[0041] The results are as follows Figure 6 As shown, CQD@UiO-66-NH2 / PSF exhibits particularly outstanding photocatalytic performance, achieving a 100% degradation efficiency of tetracycline with a rate constant of 0.02768 min⁻¹ at a catalyst dosage of 0.5 g / L. -1Without a photocatalyst, the TC concentration decreased only slightly, attributed to the direct photolysis effect of light. However, the introduction of a photocatalyst significantly enhanced TC removal. Due to the porous structure of CQD@UiO-66-NH2, it facilitated the absorption of approximately 18% of TC before degradation. The addition of CQD significantly increased the final TC removal rate of CQD@UiO-66-NH2 / PSF to 100%, which is 1.4 times that of UiO-66-NH2 / PSF, achieving an optimal removal rate of 0.05 mg·L⁻¹. -1 ·min -1 .

[0042] Figure 7 The degradation kinetics of TC follow a pseudo-first-order reaction mode, indicating typical heterogeneous catalysis. ln(C0 / C) t The relationship between time and CQD@UiO-66-NH2 highlights that CQD@UiO-66-NH2 significantly accelerates the degradation of TC. The reaction rate constant (k) of CQD@UiO-66-NH2 / PSF is 0.02768 min. -1 The reaction rate constant (k) for direct photolysis is 0.02768 min. -1 The reaction rate constant (k) for UiO-66-NH2 / PSF is 0.00672 min. -1 The reaction rate constant (k) for direct photolysis is 0.00351 min. -1 This indicates that CQD@UiO-66-NH2 / PSF exhibits excellent catalytic efficiency in the decomposition of TC molecules.

[0043] Example 6: Recycling performance of CQD@UiO-66-NH2 / PSF The CQD@UiO-66-NH2 / PSF (or UiO-66-NH2 / PSF) prepared in Example 4 was subjected to adsorption and photocatalytic degradation of tetracycline according to the method in Example 5. The catalyst was then recovered by centrifugation, thoroughly washed with deionized water to remove residual contaminants, and dried for reuse in subsequent experiments. The catalyst recovery rate was obtained by dividing the mass of the separated catalyst by the initial mass of the catalyst. (C...) t The adsorption rate and degradation rate are calculated using (-C0) / C0.

[0044] Figure 8 The high level of microsphere recovery after each cycle demonstrates the durability of photocatalytic activity and highlights the recyclability of organic pollutants by the CQD@UiO-66-NH2 / PSF composite microspheres. Figure 9By comparing the dark adsorption and photocatalytic degradation efficiencies of different microspheres during cycling, CQD@UiO-66-NH2 / PSF exhibited excellent structural durability and consistent photocatalytic performance across multiple cycles. This demonstrates that the microspheres prepared in this invention have excellent performance in terms of stability and recyclability.

Claims

1. A method for preparing polysulfone hollow porous microspheres stabilized by carbon quantum dot-modified MOF nanoparticles for photocatalytic degradation of organic pollutants, characterized in that, Includes the following steps: (1) ZrCl4 and 2-aminoterephthalic acid NH2-BDC were added to DMF and dispersed evenly. Then, an organic weak acid was added to pH 3-4. After mixing, a hydrothermal reaction was carried out. The product was separated and purified to obtain UiO-66-NH2. (2) Dissolve citric acid and ethylenediamine in water, heat to react, and separate the product by dialysis to obtain functionalized CQD; (3) Functionalized CQD and UiO-66-NH2 aqueous solution were mixed and reacted in the presence of N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride EDC and N-hydroxysuccinimide NHS. The reaction solution was separated and purified to obtain CQD@UiO-66-NH2. (4) Polysulfone and polyvinylpyrrolidone (PVP) were added to N-methylpyrrolidone (NMP) and dichloromethane at a volume ratio of 1:5 to obtain a mixture; CQD@UiO-66-NH2 was then added and mixed, followed by a coagulation bath to form CQD@UiO-66-NH2 / PSF hollow porous microspheres. The microspheres were then filtered, washed, and dried to obtain CQD@UiO-66-NH2 / PSF hollow porous microspheres. In step (2), the mass ratio of citric acid to ethylenediamine is 1:1-3:1; the reaction temperature is 150℃-170℃; and the reaction time is 5-8 hours. In step (3), the mass ratio of CQD to UiO-66-NH2 is 1:500-1:50; In step (4), the mass ratio of CQD@UiO-66-NH2 to polysulfone is 0.08:1-0.88:

1.

2. The preparation method according to claim 1, characterized in that, In step (1), the molar ratio of ZrCl4 to NH2-BDC is 1:2-1:3; the added mass of DMF is 5-10 times the sum of the masses of ZrCl4 and NH2-BDC; the organic weak acid is selected from formic acid or acetic acid; In step (1), the temperature of the hydrothermal reaction is 120℃-150℃; the reaction time is 20-26 hours. In step (2), the mass ratio of citric acid to ethylenediamine is 2:1; In step (2), the molecular weight cutoff for dialysis is 500-2000; In step (3), the mass ratio of CQD to UiO-66-NH2 is 1:100; the amount of EDC used is 0.1 wt%-0.3 wt% of UiO-66-NH2; and the amount of NHS used is 0.2 wt%-0.5 wt% of UiO-66-NH2. In step (4), the mass ratio of CQD@UiO-66-NH2 to polysulfone is 0.4:1-0.8:1; the content of PVP in the mixture is 0.5 wt%-5 wt%.

3. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of ZrCl4 to NH2-BDC is 1:2; the added mass of DMF is 8-10 times the sum of the masses of ZrCl4 and NH2-BDC. In step (3), the amount of EDC used is 0.1 wt% of UiO-66-NH2; the amount of NHS used is 0.3 wt% of UiO-66-NH2.

4. The preparation method according to claim 1, characterized in that, In step (1) or (3), the separation and purification are carried out by solvent washing and centrifugation of the precipitate; the washing solvent is DMF, anhydrous ethanol or water; the centrifugation speed is 6000 rpm-12000 rpm and the time is 5-10 min.

5. A polysulfone hollow porous microsphere stabilized by carbon quantum dot-modified MOF nanoparticles, obtained by the preparation method according to any one of claims 1-4.

6. The application of polysulfone hollow porous microspheres stabilized by carbon quantum dot-modified MOF nanoparticles as described in claim 5 in the photocatalytic degradation of organic pollutants, characterized in that, The organic pollutants are organic dyes or antibiotics.

7. The application according to claim 6, characterized in that, The organic pollutant is methylene blue or tetracycline.

Images