Preparation method and application of wide pH response type MIL-88 coated CuS heterojunction material
By preparing MIL-88@CuS heterojunction material, the problems of narrow pH adaptability and rapid recombination of photogenerated charges of MIL-88 photocatalyst were solved, and efficient degradation of tetracycline was achieved over a wide pH range, with good stability and economy.
Patent Information
- Application Number
- CN202511122361.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-12
- Publication Date
- 2025-11-21
Smart Images
Figure CN120984348A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to a preparation method and application of a photocatalyst. BACKGROUND
[0002] The massive discharge of antibiotic drugs into natural water environments has become a major problem that threatens aquatic ecosystems and human health. Fenton oxidation, as a traditional AOP advanced oxidation catalytic technology, can effectively degrade stubborn organic pollutants in an acidic environment. However, the accumulation of iron-containing sludge, secondary pollution, and especially the strict requirement of acidic pH value have severely limited its large-scale application. Photocatalytic Fenton degradation is an environmentally friendly and cost-effective environmental remediation technology. The combination of Fenton oxidation and heterogeneous photocatalysts can accelerate the electron redox cycle, thereby significantly improving the degradation efficiency. MIL-88A has attracted attention in the application of photo-Fenton due to its visible light absorption ability and abundant Fe-O sites for H2O2 activation. However, MIL-88A itself has some challenges, including low electrical conductivity and rapid recombination of photo-generated charges, which limit its photocatalytic activity, especially the narrow pH adaptability. Under acidic conditions, the MOF ligand is protonated and dissolved, and under alkaline conditions, the MOF framework is easily hydrolyzed and destabilized, making it only maintain structural integrity and catalytic activity in a very narrow pH range. Therefore, developing a new photo-Fenton material with high-efficiency charge separation and wide pH stability has become a key breakthrough in solving antibiotic pollution in water bodies. SUMMARY
[0003] The present application aims to solve the technical problems of high pH requirement, rapid recombination of photo-generated charges, and slow reaction kinetics of MIL-88 photocatalysts, and provides a preparation method and application of a wide-pH-responsive MIL-88@CuS heterojunction material.
[0004] The preparation method of the wide-pH-responsive MIL-88@CuS heterojunction material of the present application is carried out according to the following steps:
[0005] I. Fe(NO3)2·9H2O and fumaric acid are added to water, heated and stirred to dissolve, obtaining a solution; the solution is transferred to a polytetrafluoroethylene-lined high-pressure reactor, then the reactor is placed in an oven, and the hydrothermal reaction is carried out at a temperature of 100-110℃ for 6-8h; then centrifugal separation is carried out, the solid phase is washed clean with deionized water, dried, and MIL-88 powder is obtained;
[0006] II. MIL-88 powder and copper chloride are added to water, ultrasonic stirring is carried out until complete dissolution, obtaining a mixed solution A;
[0007] III. Thiourea is placed in N,N-dimethylformamide (DMF), ultrasonic stirring is carried out until uniform, then deionized water is added to accelerate dissolution, obtaining a solution B;
[0008] IV. Solution B is added to the mixed solution A by a constant flow pump, and then stirred vigorously, and then transferred to a high-pressure reactor with a polytetrafluoroethylene liner, and then the reactor is placed in an oven, and then the hydrothermal reaction is carried out at a temperature of 140-150°C for 6-8h, and then the solid phase is separated by centrifugation, and then washed with DMF and ethanol in sequence, and then dried to obtain the wide pH response type MIL-88@CuS heterojunction material.
[0009] Further, the heating temperature of Fe(NO3)2·9H2O and fumaric acid in step one is 65-75°C.
[0010] Further, the mass ratio of Fe(NO3)2·9H2O to fumaric acid in step one is (3.7-4.1):1.
[0011] Further, the volume ratio of the total mass of Fe(NO3)2·9H2O and fumaric acid to water in step one is 1g:(29-47)mL.
[0012] Further, the drying in step one is in an oven at a temperature of 60-70°C for 10-12h.
[0013] Further, the mass ratio of MIL-88 to copper chloride in step two is (1.2-1.4):1.
[0014] Further, the volume ratio of the mass of thiourea to N,N-dimethylformamide in step three is 1g:(125-152)mL.
[0015] Further, the mass ratio of copper chloride in step two to thiourea in step three is 1:(1.6-1.8).
[0016] Further, the volume ratio of N,N-dimethylformamide to deionized water in step three is (2-3.5):1.
[0017] Further, the speed of the constant flow pump in step four is 90-100 mL / min.
[0018] Further, the vigorous stirring speed of the stirrer in step four is 800-900 r / min.
[0019] Further, the drying in step four is in an oven at a temperature of 60-65°C for 10-12h.
[0020] The application of the wide pH response type MIL-88@CuS heterojunction material prepared by the above method is that the wide pH response type MIL-88@CuS heterojunction material is used for photo-Fenton degradation of tetracycline.
[0021] The prepared wide pH response type MIL-88@CuS heterojunction material is constructed by MIL-88 and CuS, and CuS is a narrow-band-gap semiconductor, which is not only matched with the energy band of MIL-88A (Fe) and suitable for constructing a Z-type heterojunction, but also introduces Cu + / Cu 2+ Oxidation-reduction pairs. The Z-type heterojunction has a more stable structure, which not only inhibits the recombination of carriers, but also enhances the light absorption efficiency and improves the carrier separation efficiency, and most importantly, ensures the continuous Fenton oxygen activity in a wider pH range, solves the limitations of the traditional Fenton system, and improves the activity of the photo-Fenton degradation of tetracycline.
[0022] The wide pH response type MIL-88@CuS heterojunction material prepared by the application is used for tetracycline degradation experiment, which significantly improves the efficiency of tetracycline degradation, and the degradation rate of the MIL-88@CuS heterojunction material is increased by 21% and 28% compared with single component, which shows excellent photo-Fenton performance. At the same time, the experimental environment pH is in the range of 3-9, and the degradation rate of tetracycline is more than 80%, and when the pH is 3, the degradation rate of tetracycline reaches 98%, which greatly expands the application environment range. The photocatalytic system is driven by solar energy and operates at normal temperature and pressure, which meets the concept of sustainable development and green chemistry, and has the advantages of low energy consumption and no environmental pollution. The wide pH response type MIL-88@CuS heterojunction material used in the process of degrading tetracycline shows excellent stability and reusability, which greatly enhances the practical application prospect of the system.
[0023] The synthesis method of the heterojunction composite material of the application has a simple and efficient process route, simple and easy operation steps, significantly reduces the cost of raw materials and energy consumption, and the required equipment is conventional and has low investment threshold. This good process economy and scalability effectively overcome the cost and technical obstacles in large-scale production, and provide strong support for realizing large-scale and sustainable preparation of the material and its practical application in the field of environmental pollution control. It can be used in the field of photocatalytic degradation of tetracycline. BRIEF DESCRIPTION OF DRAWINGS
[0024] Figure 1 The SEM image of MIL-88 prepared in step one of Example 1 is shown in the figure;
[0025] Figure 2 The SEM image of CuS on the surface of the wide pH response type MIL-88@CuS heterojunction material in Example 1 is shown in the figure;
[0026] Figure 3 The SEM image of the wide pH response type MIL-88@CuS heterojunction material prepared in Example 1 is shown in the figure;
[0027] Figure 4 is an XRD spectrum of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1;
[0028] Figure 5 is a Kelvin probe diagram of MIL-88, CuS and MIL-88@CuS in the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1;
[0029] Figure 6 is a schematic diagram of Z-type heterostructure mechanism transfer between MIL-88 and CuS in the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1;
[0030] Figure 7 is a performance diagram of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1, MIL-88 and CuS respectively as catalysts for photocatalytic degradation of tetracycline;
[0031] Figure 8 is a performance diagram of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1 for degradation of tetracycline at different pH values;
[0032] Figure 9 is a performance diagram of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1 for five cycles of photocatalytic degradation of tetracycline;
[0033] Figure 10 is a performance diagram of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 2 for photocatalytic degradation of tetracycline. DETAILED DESCRIPTION
[0034] The application will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0035] Example 1: The preparation method of the wide pH-responsive MIL-88@CuS heterojunction material in this embodiment is carried out according to the following steps:
[0036] I. 0.5252 g of Fe(NO3)2·9H2O and 0.1393 g of fumaric acid were added to 30 mL of deionized water, and the solution was stirred and dissolved at 70°C to obtain an orange yellow solution; the solution was transferred to a polytetrafluoroethylene lined high-pressure reaction kettle, and then the reaction kettle was placed in an oven at a temperature of 110°C for 6 h for hydrothermal reaction; then the solid phase was separated by centrifugation and washed with deionized water until clean, and then dried in an oven at 60°C for 12 h to obtain MIL-88 powder;
[0037] II. 0.1775 g of MIL-88 powder and 0.134 g of copper chloride were added to 30 mL of deionized water, and ultrasonic stirring was performed until complete dissolution to obtain a mixed solution A;
[0038] III. 0.23 g of thiourea was placed in 30 mL of N,N-dimethylformamide (DMF), and ultrasonic stirring was performed until uniform, and then 10 mL of deionized water was added to accelerate dissolution to obtain a solution B;
[0039] IV. The solution B was added dropwise to the mixed solution A at a speed of 100 mL / min using a constant flow pump, and then vigorous stirring was performed at a rotation speed of 900 r / min, and then the reaction kettle was transferred into a polytetrafluoroethylene lined high-pressure reaction kettle, and then the reaction kettle was placed into an oven, and then a hydrothermal reaction was performed at a temperature of 150℃ for 8 h, and then the solid phase was separated by centrifugation, and then the solid phase was washed with DMF and ethanol three times in sequence, and then the solid phase was placed into an oven at a temperature of 60℃ for drying for 12 h to obtain a wide pH responsive MIL-88@CuS heterojunction material.
[0040] The scanning electron microscope photograph of the MIL-88 prepared in step I of the example is shown in Figure 1 It can be seen from Figure 1 that the MIL-88 is rod-shaped and has a smooth surface, which is beneficial to the subsequent loading of the material.
[0041] The SEM graph of the surface CuS of the wide pH responsive MIL-88@CuS heterojunction material prepared in step IV of the example is shown in Figure 2 It can be seen from Figure 2 that the CuS is flower-shaped structure with uniform size, and the size is 3-4 microns, and the surface is slightly rough.
[0042] The SEM graph of the wide pH responsive MIL-88@CuS heterojunction material prepared in step IV of the example is shown in Figure 3 It can be seen from Figure 3 that the CuS is uniformly coated on the outer surface of the MIL-88, and the MIL-88@CuS presents a typical core-shell structure.
[0043] The XRD spectrum of the wide pH responsive MIL-88@CuS heterojunction material prepared in step IV of the example is shown in Figure 4 It can be seen from Figure 4It can be seen that the characteristic peaks of the copper sulfide sample at 27.6°, 29.3°, 31.8°, 32.8°, 47.9°, 52.7° and 59.3° correspond to the (101), (102), (103), (006), (110), (108) and (116) planes of the typical hexagonal structure of copper sulfide (JCPDS No. 06-0464). MIL-88 shows characteristic peaks at about 9.4°, 11.1°, 12.1° and 15.2°, which are characteristic peaks of MIL-88A (Fe). After coupling copper sulfide with MIL-88, the characteristic peaks still exist, but the peak intensity decreases slightly, which proves that the core-shell MIL-88@CuS nanocomposite material is successfully constructed.
[0044] The Kelvin probe images of MIL-88 and CuS in the wide pH responsive MIL-88@CuS heterojunction material prepared in this example are shown in Figure 5 It can be seen that the work functions of copper sulfide and MIL-88 are 5.16 eV and 5.34 eV, respectively. When copper sulfide and MIL-88 are in contact in the MIL-88@CuS sample, a contact potential difference is generated at the interface due to the difference in their work functions, which promotes the transfer of electrons from copper sulfide to MIL-88 until the Fermi levels of the two reach equilibrium.
[0045] The schematic diagram of the Z-type heterostructure mechanism transfer between MIL-88 and CuS in the wide pH responsive MIL-88@CuS heterojunction material prepared in this example is shown in Figure 6 Due to the difference in the work functions of MIL-88 and CuS, a contact potential difference is generated at the interface, which promotes the transfer of electrons until the Fermi levels of the two reach equilibrium. Therefore, an internal electric field is formed at the interface from copper sulfide to MIL-88. Under the action of this electric field, holes accumulate on the side of copper sulfide, causing the energy band to bend upwards; on the contrary, the accumulation of electrons on the interface of MIL-88 causes the energy band to bend downwards. Therefore, a Z-type charge transport channel is formed on the MIL-88 / CuS interface, i.e. the photo-generated electrons at the band region (CB) of MIL-88 can be combined with the holes in the band region (VB) of copper sulfide through the interface, thereby effectively promoting charge separation. In addition, the remaining electrons in the band structure of copper sulfide and the holes in the valence band of MIL-88 have strong redox ability, which is beneficial to the photodegradation reaction. The energy band structure of MIL-88 and CuS can achieve good band matching, promoting the separation of photo-generated electrons and holes, thereby reducing the recombination and enhancing the effective utilization rate of carriers.
[0046] The photocatalytic degradation of tetracycline was carried out simultaneously using the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1, MIL-88, and CuS as catalysts. All batch experiments were conducted at room temperature (25°C) in 100 mL glass beakers with continuous magnetic stirring. 10 mg of catalyst was dispersed in 100 mL of a 20 ppm tetracycline solution to obtain a suspension. After stirring in the dark for 30 minutes, 10 μL of a 30% hydrogen peroxide solution was rapidly injected into the suspension, and the suspension was irradiated with a 300 W xenon lamp equipped with a 420 nm cutoff filter. Subsequently, 3 mL of the suspension was collected every 5 minutes, filtered through a 0.22 μm filter membrane, and the tetracycline concentration was analyzed using a UV-Vis spectrophotometer at 357 nm to calculate the tetracycline removal rate. The wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1, and the performance of MIL-88 and CuS as catalysts for photo-Fenton degradation of tetracycline are shown in the figure. Figure 7 As shown, from Figure 7 As can be seen, the tetracycline degradation rate of the pH-responsive MIL-88@CuS heterojunction material is 93%, compared to 72% for MIL-88 and 65% for CuS. The degradation rate of the pH-responsive MIL-88@CuS heterojunction material is 21% and 28% higher than that of MIL-88 and CuS, respectively, demonstrating excellent photo-Fenton performance. The construction of a photocatalytic-Fenton-like bifunctional synergistic system based on the Z-type MIL-88@CuS heterojunction overcomes the limitations of traditional photocatalysis and single Fenton reaction systems. This breakthrough effectively solves the serious problems of charge recombination and insufficient metal cycling kinetics in traditional photocatalytic-Fenton systems, significantly improving the tetracycline degradation efficiency.
[0047] The performance of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1 in degrading tetracycline at different pH values is shown in the figure. All batch experiments were conducted at room temperature (25°C) using 100 mL glass beakers with continuous magnetic stirring at pH 3, 5, 7, and 9. Typically, 10 mg of MIL-88@CuS was dispersed in 100 mL of a 20 ppm TC solution. After stirring in the dark for 30 minutes, hydrogen peroxide solution was rapidly injected into the suspension. Simultaneously, the suspension was irradiated with a 300 W xenon lamp equipped with a 420 nm cutoff filter. Subsequently, 3 mL of the suspension was collected at regular intervals. The resulting solution was then diluted with a 0.22 μm filter membrane and analyzed using a UV-Vis spectrophotometer at 357 nm. The performance of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1 in degrading tetracycline at different pH values is shown in the figure. Figure 8As shown in the figure, it can be seen that the pH value of the solution is reduced from 9 to 3, and the degradation efficiency of TC shows a monotonic increasing trend, and when pH = 3, the removal rate of TC reaches 98%, which proves that the material has a wide pH range and a wide application range.
[0048] Five cycles of photocatalytic degradation experiments were performed using the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1. All batch experiments were performed in a 100-milliliter glass beaker at room temperature (25°C) with constant magnetic stirring. Typically, a certain amount of MIL-88@CuS was dispersed in 100 milliliters of a TC solution with a concentration of 20 ppm. After stirring in the dark for 30 minutes, hydrogen peroxide solution was rapidly injected into the suspension. At the same time, the suspension was irradiated using a 300W xenon lamp with a 420nm cutoff filter. Then, 3 milliliters of the suspension were collected at regular intervals. Subsequently, the resulting solution was filtered using a 0.22-micron filter and analyzed using a UV-Vis spectrophotometer at a wavelength of 357 nanometers. The remaining catalyst in the beaker was then centrifuged and dried, and the dried catalyst was subjected to the experimental process repeatedly for five times. The performance graph of the wide pH-responsive MIL-88@CuS heterojunction material prepared in Example 1 in five cycles of photocatalytic degradation of tetracycline is shown in Figure 2. Figure 9 As shown in the figure, it can be seen that after five cycles, the recovered catalyst still maintains good photocatalytic activity, further demonstrating that the catalyst has good stability and is suitable for long-term application in actual catalytic processes.
[0049] Example 2: This example is different from Example 1 in that step four is replaced by the following operation:
[0050] IV. The B solution was added to the mixed solution A at a speed of 100 mL / min using a constant flow pump, and then stirred vigorously at a speed of 900 r / min. Subsequently, the reaction kettle was transferred to a polytetrafluoroethylene-lined high-pressure reaction kettle, and the reaction kettle was placed in an oven at a temperature of 150°C for 6h for hydrothermal reaction. Then, the solid phase was separated by centrifugation, washed with DMF and ethanol three times in turn, and then placed in an oven at a temperature of 60°C for drying for 12h to obtain a core-shell structure MIL-88@CuS heterojunction material.
[0051] The other steps and parameters are the same as in Example 1 to obtain a wide pH-responsive MIL-88@CuS heterojunction material.
[0052] The MIL-88@CuS heterojunction material prepared in Example 2 was used for the photo-Fenton degradation of tetracycline. The photo-Fenton degradation of tetracycline was carried out using a 300 W xenon lamp at room temperature (25 °C) in a 100 mL glass beaker with continuous magnetic stirring. 10 mg of catalyst was dispersed in 100 mL of a tetracycline solution with a concentration of 20 ppm to obtain a suspension; after stirring in the dark for 30 min, 10 μL of a 30% mass fraction hydrogen peroxide solution was rapidly injected into the suspension, and at the same time, the suspension was irradiated using a 300 W xenon lamp with a 420 nm cut-off filter. Then, every 5 min, 3 mL of the suspension was collected, filtered using a 0.22 μm filter membrane, and the obtained solution was analyzed for the concentration of tetracycline at a wavelength of 357 nm using a UV-visible spectrophotometer, and the removal rate of tetracycline was calculated. The performance of the MIL-88@CuS heterojunction material prepared in Example 2 in the photocatalytic degradation of tetracycline is shown in the graph of Figure 10 Figure 10 It can be seen that the MIL-88@CuS heterojunction material prepared in Example 2 has a tetracycline degradation rate of 82.8% within 30 min.
[0053] The above description of the examples is intended to facilitate the understanding and use of the invention by those of ordinary skill in the art. Those skilled in the art can obviously make various modifications to these examples and apply the general principles described herein to other examples without having to go through creative labor. Therefore, the present invention is not limited to the above examples, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.
Claims
1. A method for preparing a wide pH-responsive MIL-88@CuS heterojunction material, characterized in that, The method is carried out according to the following steps: I. Fe(NO3)2·9H2O and fumaric acid are added to water, heated and stirred to dissolve, to obtain a solution; the solution is transferred to a polytetrafluoroethylene-lined high-pressure reaction kettle, and then the reaction kettle is placed in an oven, and the hydrothermal reaction is carried out at a temperature of 100-110℃ for 6-8h; then centrifugal separation is carried out, the solid phase is washed clean with deionized water, and dried to obtain MIL-88 powder; II. MIL-88 powder and copper chloride are added to water, and ultrasonic stirring is carried out until completely dissolved, to obtain a mixed solution A; III. Thiourea is placed in N,N-dimethylformamide, and ultrasonic stirring is carried out until uniform, and then deionized water is added to accelerate dissolution, to obtain a solution B; IV. Solution B is added dropwise to mixed solution A using a constant flow pump, and then vigorous stirring is carried out, and then transferred to a polytetrafluoroethylene-lined high-pressure reaction kettle, and then the reaction kettle is placed in an oven, and the hydrothermal reaction is carried out at a temperature of 140-150℃ for 6-8h, and then the solid phase is centrifugally separated, and sequentially washed clean with DMF and ethanol, and then dried, to obtain a wide pH response type MIL-88@CuS heterojunction material.
2. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1, characterized in that, The dissolution temperature of Fe(NO3)2·9H2O and fumaric acid in step I is 65-75℃.
3. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The mass ratio of Fe(NO3)2·9H2O to fumaric acid in step I is (3.7-4.1):
1.
4. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The total mass of Fe(NO3)2·9H2O and fumaric acid to the volume of water in step I is 1g:(29-47)mL.
5. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The drying in step I is carried out in an oven at a temperature of 60-70℃ for 10-12h.
6. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The mass ratio of MIL-88 to copper chloride in step II is (1.2-1.4):
1.
7. The preparation method of the wide pH response MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The ratio of the mass of thiourea to the volume of N,N-dimethylformamide in step III is 1g:(125-152)mL.
8. The preparation method of the wide pH-responsive MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The volume ratio of N,N-dimethylformamide to deionized water in step III is (2-3.5):
1.
9. The preparation method of the wide pH-responsive MIL-88@CuS heterojunction material according to claim 1 or 2, characterized in that, The vigorous stirring speed of the stirrer in step IV is 800-900r / min.
10. The use of the wide pH-responsive MIL-88@CuS heterojunction material prepared by the method of claim 1, characterized in that, The application is to use the wide pH response type MIL-88@CuS heterojunction material for photo-Fenton degradation of tetracycline.