Method for preparing ZIF-67 / Ni-MOF (at) TiO2 composite material photocatalyst and application of ZIF-67 / Ni-MOF (at) TiO2 composite material photocatalyst in antibacterial and mildew-removing aspects

Abstract

The invention relates to a ZIF-67 / Ni-MOF (at) TiO2 photocatalyst, and the ZIF-67 / Ni-MOF (at) TiO2 photocatalyst is prepared by taking TiO2 as a precursor through a hydrothermal synthesis method. Staphylococcus aureus, escherichia coli and aspergillus are used as tested strains, and the antibacterial performance of the composite photocatalyst within 3 hours is measured. Results show that compared with other photocatalysts, the ZIF-67 / Ni-MOF (at) TiO2 composite material shows the strongest photocatalytic antibacterial performance, when the concentration of bacterial liquid is 105 CFU / mL and 107 CFU / mL and the exposure time is 3 h, aspergillus is completely removed within 2 h, the removal rate of staphylococcus aureus and escherichia coli is 100% within 1.5 h, and the ZIF-67 / Ni-MOF (at) TiO2 composite material has a great application prospect as an environment-friendly antibacterial material in the furniture industry.

Description

Technical Field

[0001] The present invention relates to the technical field of photocatalysts, and in particular to a method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst and its application in antibacterial and mildew removal. Background Art

[0002] In recent years, photocatalytic antibacterial technology has become a research hotspot due to its high efficiency and environmental friendliness. Compared with traditional antibacterial methods, photocatalytic technology can not only quickly inactivate pathogenic microorganisms, but also effectively degrade bacterial metabolites, avoiding secondary pollution.

[0003] Metal-organic frameworks (MOFs) have become important vehicles for the design of functional materials due to their unique topological structure. Their high specific surface area and pore volume provide an ideal microenvironment for the loading of photocatalysts. Their three-dimensional, hierarchical pores not only physically retain microorganisms, but also enhance bacterial adsorption through coordination via open metal sites. When combined with TiO2, ZIF-67 / Ni-MOF@TiO2 forms a dynamic synergistic "adsorption-photocatalysis" system: the MOF framework rapidly accumulates bacteria attached to the mattress surface, while the TiO2, under visible light excitation, produces reactive oxygen species (ROS), which directly damage the integrity of bacterial cell membranes. This dual mechanism enables the material to achieve rapid antibacterial activity even under low-intensity conditions, making it particularly suitable for furniture interiors with limited light conditions.

[0004] Numerous studies have shown that photocatalytic antibacterial technology has become a mature technology. Immobilizing a photocatalyst on two metal-organic frameworks (MOFs) allows for the construction of a hierarchical porous system. This system leverages the MOFs' enormous surface area and high porosity to unleash their unique adsorption properties, helping the loaded photocatalyst capture bacteria or mold, achieving a synergistic adsorption-photocatalytic effect and enhancing its photocatalytic performance. However, current research on the application of dual-MOF composite systems for the inactivation of mold and bacteria is relatively limited.

[0005] Based on this background, the inventors successfully developed a modified TiO2 (ZIF-67 / Ni-MOF@TiO2) composite photocatalyst. Through the synergistic effect of metal-organic framework materials and semiconductor materials, the band gap of TiO2 was adjusted to 2.06 eV. The solar energy utilization efficiency after the modification was increased by 44%. Experiments were carried out using Staphylococcus aureus, Escherichia coli and Aspergillus as typical test bacteria. The results showed that the material had a significant effect on the bacterial solution concentration of 10 5 CFU / mL and 10 7 The mixed bacterial community with a CFU / mL has a significant removal effect. Aspergillus was completely eliminated within 2 hours, and the removal rates of Gram-positive and Gram-negative bacteria reached 100% within 1.5 hours, showing great potential as an antibacterial material for bed boards. Summary of the Invention

[0006] The present invention aims to provide a modified TiO2 (ZIF-67 / Ni-MOF@TiO2) composite photocatalyst and its preparation method. TiO2 is surface-modified and then loaded with the metal-organic framework (ZIF-67) and Ni-MOF via a solvothermal method to form a ZIF-67 / Ni-MOF@TiO2 composite. Its highly effective visible-light photocatalytic antibacterial properties against Staphylococcus aureus, Escherichia coli, and Aspergillus fusiformis were verified. By manipulating the crystalline structure and surface properties of TiO2 and combining them with the multi-level pores of ZIF-67 / Ni-MOF, the composite material is endowed with significant adsorption and enrichment capabilities, achieving a dual-functional "adsorption-photocatalytic" synergistic antibacterial mechanism. The introduction of ZIF-67 / Ni-MOF reduces the composite's band gap to 2.06 eV, improving its solar energy utilization efficiency in the visible light region by 44% compared to pure TiO2, thereby enhancing the composite's visible light utilization capability. This invention utilizes the ZIF-67 / Ni-MOF composite TiO2 photocatalyst to inactivate bacteria and molds, enhancing antibacterial activity.

[0007] The technical solution of the present invention is: A method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst comprises the following steps: Step 1: Dissolve 1.56 g of thiourea in 60 mL of deionized water with magnetic stirring. Subsequently, add 40 mL of anhydrous ethanol and 5 mL of triethanolamine. After complete dissolution, add 10 mL of butyl titanate dropwise to the mixture, followed by 0.1 mL of phosphoric acid. Stir magnetically for 30 minutes, transfer to an autoclave, heat to 210°C over 90 minutes, and maintain for 4 hours. After cooling, collect the precipitate by centrifugation and wash twice with deionized water and anhydrous ethanol. Dry under vacuum at 50°C to obtain modified TiO2.

[0008] Step 2: Dissolve 11.35 g of NiSO4·6H2O in 72 mL of N,N-dimethylformamide to prepare solution A, dissolve 1.20 g of terephthalic acid in 72 mL of N,N-dimethylformamide to prepare solution B, and then add solution B to solution A and stir for 30 min. Then add 1 g of modified TiO2, and seal the resulting mixture in a 150 ml autoclave and heat. After cooling, centrifuge and wash with N,N-dimethylformamide and ethanol three times respectively. Finally, vacuum dry at 70°C to obtain Ni-MOF@TiO2; Step three: 1 g of Ni-MOF@TiO2 was dissolved in 500 mL of ethanol by ultrasonic for 30 min, 9.99 g of Co(NO3)2·6H2O was added, and continuous stirring was carried out for 3 h to prepare solution A. 20 g of 2-methylimidazole was dissolved in 500 mL of ethanol and stirred for 25 min to prepare solution B. Solution B was added to solution A, stirred, centrifuged at 4500 rpm for 15 min with ethanol, washed 3 times to remove impurities, and finally vacuum dried to obtain a stable composite ZIF-67 / Ni-MOF@TiO2.

[0009] Preferably, in step two, the heating condition of the reaction kettle is heating at 160℃ for 18 h.

[0010] Preferably, in step three, the stirring time is 24 h, and the vacuum drying temperature is 70℃.

[0011] The ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared by the above preparation method is disclosed. The composite photocatalyst prepared by the present application is confirmed to have crystal face characteristic peaks belonging to ZIF-67 and Ni-MOF respectively in the X-ray diffraction spectrum (XRD), and the scanning electron microscope picture proves that the prepared photocatalyst is a rhombic dodecahedron with perfect morphology. Containing C=N, Ti-O, O-H and other functional groups, indicating the structural stability of the photocatalyst. The incorporation of ZIF-67 and Ni-MOF materials reduces the intrinsic band gap of TiO2 to 2.06 eV, and greatly improves the visible light absorption capacity of the photocatalyst. X-ray photoelectron spectroscopy (XPS) confirms that the high binding energy peak (~533.2 eV) of ZIF-67 / Ni-MOF@TiO2 belongs to the active oxygen chemisorbed on the surface in the photocatalytic process, which is closely related to the generation ability of oxygen vacancies and free radicals.

[0012] The application of the ZIF-67 / Ni-MOF@TiO2 photocatalyst in bacteriostasis is disclosed. Preferably, the test bacteria are Staphylococcus aureus, Escherichia coli and Aspergillus. When inactivating the bacteria, the addition amount of the catalyst is 4 g / L, and the treatment time is 3 h.

[0013] In the present application, the test bacteria are Staphylococcus aureus, Escherichia coli and Aspergillus, because their individual body size is small and easy to observe, the growth and reproduction speed is fast, the generation cycle is short, and they are easy to cultivate, and many antibacterial material test standards (such as ISO20743, JIS Z 2801) recommend using Escherichia coli and Staphylococcus aureus as typical bacteria, and Aspergillus as a representative of fungi, to ensure the universality and recognition of the experimental results. Therefore, the present application uses the three as the experimental test bacteria. Under laboratory conditions, the preparation of potato glucose agar for cultivating Aspergillus adopts the following technical scheme: 1) First, prepare 200 g / L potato extract, mix it with 20 g / L glucose, and distribute it in conical flasks. Autoclave the mixture at 121℃ for 20 minutes, cool it down, transfer it to centrifuge tubes, and pour off the supernatant after centrifugation to obtain potato glucose agar.

[0014] 2) After the Aspergillus is cultured for 3-7 days at 37℃, the Aspergillus spore suspension is adjusted to about 10 5 CFU / mL and 10 7 CFU / mL in standby.

[0015] The activation, amplification, and identification steps of Staphylococcus aureus and Escherichia coli are as follows: 1) First, plate the refrigerated Staphylococcus aureus and Escherichia coli strains on solid LB medium, and place them in an artificial climate incubator for 24 hours. Then, pick a single colony with a sterile toothpick and place it in liquid LB medium, and incubate it in a shaking incubator for 12 hours.

[0016] 2) Transfer the cultured bacterial solution to a centrifuge tube, centrifuge it, and pour off the supernatant. Wash the bacterial cells in the centrifuge tube twice with PBS buffer, and adjust the concentration of the bacterial suspension to about 10 5 CFU / mL and 10 7 CFU / mL in standby.

[0017] The composite photocatalyst prepared by the present application can be used to inhibit mold and bacteria on bed boards in a humid environment. To strengthen the antibacterial treatment, first dilute the Aspergillus, Staphylococcus aureus, and Escherichia coli suspensions to the target concentration (10 5 and 10 7 CFU / mL), then a certain amount of photocatalyst can be weighed and placed in the three suspensions for ultrasonic dispersion, and the mixture is shaken regularly to increase the contact area between the photocatalyst and the bacterial strains, and further prevent the settlement of the photocatalyst particles. The mixture is exposed to natural light for photocatalytic reaction Compared with existing antibacterial technologies, the present application has the following advantages: 1. The ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared by the present application has high photocatalytic activity, wide light absorption range, excellent adsorption performance, and can perform photocatalytic reaction under visible light, and the required treatment conditions are simple and easy to obtain.

[0018] 2. The present application shortens the band gap of the initial photocatalyst TiO2 to 2.06 eV, significantly increases the visible light absorption range, and significantly reduces the recombination efficiency of photo-generated electron-hole pairs 3. MOF materials provide a huge specific surface area and a high-porosity mesoporous structure, which gives the composite material special adsorption properties, making the photocatalytic antibacterial effect the result of adsorption-photocatalytic synergistic effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a scanning electron microscope image of the prepared modified TiO2 photocatalyst.

[0020] Figure 2 This is a scanning electron microscope image of the prepared Ni-MOF@TiO2 photocatalyst.

[0021] Figure 3 This is a scanning electron microscope image of the prepared ZIF-67 / Ni-MOF@TiO2 photocatalyst.

[0022] Figure 4 This is the XPS spectrum of the prepared ZIF-67 / Ni-MOF@TiO2 photocatalyst.

[0023] Figure 5 The ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared in Example 1 and the TiO2 and Ni-MOF@TiO2 prepared under the same conditions were treated under visible light for 3 h, and the suspension concentration was 10 5 Line graph of the inactivation rate of Aspergillus, Staphylococcus aureus, and Escherichia coli in CFU / mL.

[0024] Figure 6 The ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared in Example 1 and the TiO2 and Ni-MOF@TiO2 prepared under the same conditions were treated under visible light for 3 h, and the suspension concentration was 10 7 Line graph of the inactivation rate of Aspergillus, Staphylococcus aureus, and Escherichia coli in CFU / mL. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1 A preparation method of ZIF-67 / Ni-MOF@TiO2 photocatalyst, the specific steps are as follows: 1) Dissolve 1.56 g of thiourea in 60 mL of deionized water with magnetic stirring. Subsequently, add 40 mL of anhydrous ethanol and 5 mL of triethanolamine. Once completely dissolved, add 10 mL of butyl titanate dropwise to the mixture, followed by 0.1 mL of phosphoric acid. Stir magnetically for 30 minutes, transfer to an autoclave, heat to 210°C over 90 minutes, and maintain for 4 hours. After cooling, collect the precipitate by centrifugation and wash twice with deionized water and anhydrous ethanol. Dry under vacuum at 50°C to obtain modified TiO2.

[0027] 2) Dissolve 11.35 g of NiSO4·6H2O in 72 mL of N,N-dimethylformamide to prepare solution A. Dissolve 1.20 g of terephthalic acid in 72 mL of N,N-dimethylformamide to prepare solution B. Add solution B to solution A and stir for 30 minutes. Then, add 1 g of TiO2. The resulting mixture is sealed in a 150 ml autoclave and heated at 160°C for 18 hours. After cooling, the mixture is washed by centrifugation three times with N,N-dimethylformamide and ethanol. Finally, vacuum dry at 70°C to obtain Ni-MOF@TiO2. 3) 1 g of Ni-MOF@TiO2 was dissolved in 500 mL of ethanol by ultrasonication for 30 minutes. 9.99 g of Co(NO3)2·6H2O was added and stirred continuously for 3 hours to prepare Solution A. 20 g of 2-methylimidazole was dissolved in 500 mL of ethanol and stirred for 25 minutes to prepare Solution B. Solution B was added to Solution A and stirred for 24 hours. The mixture was then centrifuged at 4500 rpm for 15 minutes with ethanol and washed three times to remove impurities. Finally, the mixture was dried under vacuum at 70°C to obtain a stable ZIF-67 / Ni-MOF@TiO2 composite material.

[0028] Test 1: Aspergillus, Staphylococcus aureus, and Escherichia coli were tested, and colony-forming units (CFU / mL) were calculated based on the number of colonies. Samples were collected at 0.5, 1, 1.5, 2, 2.5, and 3 hours, and bacterial concentrations were immediately determined using a standard plate count method: 100 μL of the diluted sample was plated on LB agar plates, incubated at 37°C for 24 hours, and CFU / mL was calculated. Three replicates were performed at each time point, and the results were averaged. The formula for calculating bacterial concentration is: Bacterial concentration (CFU / mL) = colony count × 10 × dilution factor Test 2: Aspergillus, Staphylococcus aureus and Escherichia coli were used as the test bacteria, and the inactivation rate was used as the indicator to explore the antibacterial effect of ZIF-67 / Ni-MOF@TiO2 photocatalyst. The suspensions of Aspergillus, Staphylococcus aureus and Escherichia coli (E. coli) were diluted to the target concentration (10 5 CFU / mL and 10 7CFU / mL). Aliquot into 250 mL conical flasks. Set up three replicates for each experimental group, and take the average of the replicate groups. Add a photocatalyst and expose to natural light for the photocatalytic reaction. Count every 0.5 h, plot the inactivation curve, and calculate the inactivation rate. The inactivation rate is calculated as follows: R=(C0-C) / C0 R: degradation efficiency; C0: initial concentration of bacterial solution; C: bacterial solution concentration at a certain time point Example 2: Antibacterial effect of TiO2 photocatalyst prepared under the same conditions The modified TiO2 photocatalyst prepared under the same conditions obtained modified TiO2 white powder.

[0029] The experimental conditions of Test 1 and Test 2 were the same as those of Example 1. Aspergillus, Staphylococcus aureus and Escherichia coli were used as the test strains, and the inactivation rate of the strains was used as an indicator to explore the antibacterial effect of the TiO2 photocatalyst.

[0030] Example 3: Antibacterial effect of Ni-MOF@TiO2 photocatalyst prepared under the same conditions The Ni-MOF@TiO2 photocatalyst was prepared under the same conditions to obtain Ni-MOF@TiO2 photocatalyst powder.

[0031] The experimental conditions of Test 1 and Test 2 were the same as those of Example 1. Aspergillus, Staphylococcus aureus and Escherichia coli were used as the test strains, and the inactivation rate of the strains was used as an indicator to explore the antibacterial effect of the TiO2 photocatalyst.

[0032] Example 4: Antibacterial effect of ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared under the same conditions The ZIF-67 / Ni-MOF@TiO2 photocatalyst was prepared under the same conditions to obtain ZIF-67 / Ni-MOF@TiO2 photocatalyst powder.

[0033] The experimental conditions of Test 1 and Test 2 were the same as those of Example 1. Aspergillus, Staphylococcus aureus and Escherichia coli were used as the test strains, and the inactivation rate of the strains was used as an indicator to explore the antibacterial effect of the TiO2 photocatalyst.

[0034] Depend on Figure 5 It can be seen that the results show that when the concentration of Aspergillus, Staphylococcus aureus and Escherichia coli suspension is 10 5 CFU / mL increased with time, and within 3 h of the photocatalytic reaction process, ZIF-67 / Ni-MOF@TiO2 showed excellent antibacterial performance. Figure 5In (a), ZIF-67 / Ni-MOF@TiO2 achieved 100% inactivation of Staphylococcus aureus within 1.5 h, Ni-MOF@TiO2 achieved it within 3 h, while the inactivation rate of TiO2 within 3 h only reached 90%. Figure 5 In (b), ZIF-67 / Ni-MOF@TiO2 has a clear advantage in inactivating Aspergillus, achieving complete inactivation within 2 h. Ni-MOF@TiO2 requires 3 h for complete removal, while modified TiO2 requires more than 3 h. Figure 5 (c) The inactivation rates of ZIF-67 / Ni-MOF@TiO2, Ni-MOF@TiO2 and TiO2 within 1.5 h were 100%, 65% and 62.5%, respectively, with significant photocatalytic performance.

[0035] Depend on Figure 6 It can be seen that the results show that when the concentration of Aspergillus, Staphylococcus aureus and Escherichia coli suspension is 10 7 CFU / mL, ZIF-67 / Ni-MOF@TiO2 showed excellent photocatalytic antibacterial effect. Figure 6 (a) The inactivation rates of ZIF-67 / Ni-MOF@TiO2, Ni-MOF@TiO2 and TiO2 within 1.5 h were 100%, 60% and 55%, respectively. At the same time, ZIF-67 / Ni-MOF@TiO2 showed excellent antifungal properties ( Figure 6 (b) ), completely eradicated Aspergillus within 2 h. This represents a 33% reduction in treatment time compared to other photocatalysts that require ≥3 h to achieve equivalent removal efficiency. ZIF-67 / Ni-MOF@TiO2 exhibited the fastest E. coli inactivation kinetics among all tested materials ( Figure 6 (c)), which means that it has the best photocatalytic antibacterial performance.

[0036] The above description is only a preferred embodiment of the present invention, and all changes and modifications made according to the scope of the patent application of the present invention are within the scope of the present invention.

Claims

1. A method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst, characterized in that: The following steps are involved: Step 1: dissolve thiourea in deionized water, add anhydrous ethanol and triethanolamine, add butyl titanate dropwise after dissolution, add phosphoric acid after the addition is complete, heat, cool and dry to obtain modified TiO2; Step 2: Dissolve NiSO4·6H2O in N,N-dimethylformamide to prepare solution A, dissolve terephthalic acid in N,N-dimethylformamide to prepare solution B, then add solution B to solution A and stir; then add TiO2 prepared in step 1, seal the resulting mixture and heat it; cool, centrifuge, wash, and dry to obtain Ni-MOF@TiO2; Step 3: Dissolve Ni-MOF@TiO2 in ethanol by ultrasonication, add Co(NO3)2·6H2O, and stir continuously to obtain solution A; dissolve 2-methylimidazole in ethanol and stir to obtain solution B; add solution B to solution A, stir, centrifuge for 15, wash and dry to obtain the composite material ZIF-67 / Ni-MOF@TiO2.

2. The method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 1, characterized in that: Step 1: Dissolve 1.56 g of thiourea in 60 mL of deionized water and stir magnetically; then, add 40 mL of anhydrous ethanol and 5 mL of triethanolamine; after complete dissolution, drop 10 mL of butyl titanate into the mixture, and then add 0.1 mL of phosphoric acid; stir magnetically for 30 minutes, transfer to an autoclave, heat to 210°C over 90 minutes, and maintain for 4 hours; after cooling, collect the precipitate by centrifugation, wash twice with deionized water and anhydrous ethanol; and vacuum dry at 50°C to obtain modified TiO2.

3. The method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 2, characterized in that: Step 2: Dissolve 11.35 g of NiSO4·6H2O in 72 mL of N,N-dimethylformamide to prepare solution A, and dissolve 1.20 g of terephthalic acid in 72 mL of N,N-dimethylformamide to prepare solution B. Then, add solution B to solution A and stir for 30 min; then add 1 g of modified TiO2, seal the resulting mixture in a 150 ml high-pressure reactor and heat; after cooling, centrifuge and wash with N,N-dimethylformamide and ethanol three times respectively; finally, vacuum dry at 70°C to obtain Ni-MOF@TiO2.

4. The method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 3, characterized in that: Step 3: Dissolve 1 g of Ni-MOF@TiO2 in 500 mL of ethanol by ultrasonication for 30 min, add 9.99 g of Co(NO3)2·6H2O, and stir continuously for 3 h to prepare solution A; dissolve 20 g of 2-methylimidazole in 500 mL of ethanol and stir for 25 min to prepare solution B; add solution B to solution A, stir, centrifuge with ethanol at 4500 rpm for 15 min, wash three times to remove impurities, and finally vacuum dry to obtain a stable composite material ZIF-67 / Ni-MOF@TiO2.

5. The method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 3, characterized in that: The heating condition of the reactor in step 2 is heating at 160°C for 18 h.

6. The method for preparing a ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 4, characterized in that: In step 3, the stirring time is 24 h and the vacuum drying temperature is 70°C.

7. A ZIF-67 / Ni-MOF@TiO2 photocatalyst prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the ZIF-67 / Ni-MOF@TiO2 photocatalyst according to claim 7 in antibacterial applications.

9. The use according to claim 8, characterized in that The tested bacterial species are Staphylococcus aureus, Escherichia coli and Aspergillus.

10. The use according to claim 8, characterized in that The amount of catalyst added to the tested strain is 4 g / L.

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