Silver cluster zeolite, method for preparing the same, and use thereof

Abstract

The application provides a silver cluster zeolite and a preparation method and application thereof, and belongs to the technical field of bactericides. A sodium hydroxide solution and sodium metaaluminate are mixed, then silica sol is added dropwise, and then aging treatment is performed to obtain an aged mixture; silver nitrate, ammonia water and water are mixed to obtain a silver ammonia solution; the silver ammonia solution is added dropwise into the aged mixture, and microwave in-situ reaction is performed to obtain the silver cluster zeolite. The application performs high-temperature rapid synthesis of ZSM-5 zeolite by means of pre-synthesis of seeds and microwave in-situ reaction, so that the synthesis speed of the zeolite and the generation rate of silver nanoparticles are approximately equal, the silver nanoparticles and the zeolite framework are synchronously synthesized, the size difference of the formed silver nanoparticles is small, and the silver nanoparticles are uniformly distributed in the framework of the zeolite.

Description

Technical Field

[0001] The present invention relates to the technical field of fungicides, and in particular to a silver cluster zeolite and a preparation method and application thereof. Background Art

[0002] Bacterial infections have always been a major challenge in the field of human health, placing a serious burden on public health and medical systems worldwide. Bacteria such as Staphylococcus aureus, Escherichia coli, and Candida albicans are among the main pathogens causing various infections, posing a serious threat to human health. Staphylococcus aureus is a Gram-positive bacterium that resides in the nares, skin, and gastrointestinal tract, frequently invading human skin, soft tissues, and blood. Escherichia coli is a commensal in the vertebrate intestine and, as an opportunistic pathogen, is increasingly involved in various intestinal and extraintestinal infections. Candida albicans is an opportunistic yeast that is the main cause of oral candidiasis and denture stomatitis. Severe conditions can even lead to life-threatening systemic infections. Therefore, the development of new fungicides has significant and far-reaching significance for human life.

[0003] Silver nanoparticles (ANPs) are novel antimicrobial agents with advantages such as high efficacy, broad-spectrum antimicrobial activity, long-lasting efficacy, and resistance to drug resistance. Therefore, the antimicrobial activity of ANPs is particularly valuable in the medical and healthcare sectors, and the incorporation of AgNPs into hundreds of products, including surgical and food handling tools, clothing, cosmetics, dental products, catheters, and dressings, has been studied. However, ANPs still have the disadvantages of being easily aggregated and difficult to recycle. Agglomeration not only affects the stability and dispersibility of ANPs but can also reduce their bactericidal properties. The recycling of ANPs is also a significant environmental and economic concern. As silver is a precious metal, its effective recovery and reuse after use is of great economic value. However, due to their tiny size, nanoscale silver particles tend to form colloids, making their recovery difficult and costly.

[0004] Zeolites are porous crystalline aluminosilicates found in nature. Their low toxicity, high surface area, and excellent stability make them a popular loading material. The most common method for synthesizing silver nanoparticles in zeolites is ion exchange. This involves first synthesizing the zeolite structure, then immersing the zeolite in a silver particle solution to exchange the silver ions for the sodium ions in the zeolite framework. The silver ions are then reduced to silver nanoparticles through heating, microwaves, or the addition of a reducing agent. However, this method produces nanoparticles with a wide range of sizes and uneven distribution. Summary of the Invention

[0005] Therefore, the present application aims to provide a silver cluster zeolite, a preparation method and application thereof.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions.

[0007] The present application provides a preparation method of a silver cluster zeolite, comprising the following steps.

[0008] The sodium hydroxide solution and sodium aluminate are mixed, then the silica sol is added dropwise, and then aging treatment is performed to obtain an aged mixture;

[0009] The silver nitrate, ammonia water and water are mixed to obtain a silver ammonia solution;

[0010] The silver ammonia solution is added dropwise into the aged mixture, microwave in-situ reaction is performed, and the silver cluster zeolite is obtained.

[0011] Preferably, the amount ratio of the sodium hydroxide solution to sodium aluminate is 3 mL:0.05 g, and the concentration of the sodium hydroxide solution is 20 wt%.

[0012] Preferably, the amount ratio of the sodium aluminate to silica sol is 0.05 g:12 mL, and the mass percentage of silicon dioxide in the silica sol is 30%.

[0013] Preferably, the amount ratio of the silica sol to silver nitrate used for preparing the silver ammonia solution is 12 mL:0.025-0.1 g, and the mass percentage of silicon dioxide in the silica sol is 30%.

[0014] Preferably, the amount ratio of the silica sol to silver nitrate used for preparing the silver ammonia solution is 12 mL:0.05-0.075 g.

[0015] Preferably, the temperature of the aging treatment is 90℃, and the time is 16 h.

[0016] Preferably, the temperature of the microwave in-situ reaction is 190℃, and the time is 5 min.

[0017] Preferably, after the silver ammonia solution is added dropwise into the aged mixture, stirring and ultrasonic treatment are sequentially performed, the time of the stirring is 30 min, and the time of the ultrasonic treatment is 10 min.

[0018] The present application also provides a silver cluster zeolite prepared by the preparation method, comprising a zeolite and a silver cluster, and the silver cluster is confined in the framework of the zeolite.

[0019] The present application also provides an application of the silver cluster zeolite in the field of sterilization.

[0020] The invention provides a preparation method of silver cluster zeolite, comprising the following steps: mixing sodium hydroxide solution and sodium metaaluminate, dropwise adding silica sol, and then performing an aging treatment to obtain an aged mixture; mixing silver nitrate, ammonia water and water to obtain a silver ammonia solution; and dropwise adding the silver ammonia solution to the aged mixture, performing a microwave in-situ reaction, and obtaining the silver cluster zeolite.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention performs high-temperature rapid synthesis of ZSM-5 zeolite by pre-synthesizing seed crystals and using microwave in-situ reaction, so that the synthesis rate of zeolite and the generation rate of silver nanoparticles are similar, and the silver nanoparticles and the zeolite framework are synthesized synchronously. The size difference of the formed silver nanoparticles is small, and the silver nanoparticles are evenly distributed in the zeolite framework.

[0023] The present invention also provides a silver cluster zeolite prepared by the preparation method described in the above technical solution. The porous structure of the zeolite is used to confine silver nanoparticles, allowing them to be evenly dispersed within the zeolite, thereby preventing the silver nanoparticles from agglomerating. Furthermore, because the zeolite as a whole is insoluble in water, it is easily recyclable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of preparing silver cluster zeolite according to an embodiment of the present invention;

[0025] Figure 2 The XRD spectrum of the silver cluster zeolite prepared in the embodiment of the present invention;

[0026] Figure 3 This is a STEM spectrum of the silver cluster zeolite prepared in an embodiment of the present invention;

[0027] Figure 4 is the particle size distribution of silver clusters in AGZ-75;

[0028] Figure 5 This is the element distribution map of AGZ-75;

[0029] Figure 6 TEM spectrum of AGZ-75;

[0030] Figure 7 is the XRD spectrum of AGZ-75;

[0031] Figure 8 This is the bactericidal dose-effect curve for different AGZ-75 addition amounts;

[0032] Figure 9 This is the AGZ-75 cyclic sterilization test curve. DETAILED DESCRIPTION

[0033] The present invention provides a method for preparing silver cluster zeolite, comprising the following steps:

[0034] After mixing sodium hydroxide solution and sodium metaaluminate, silica sol is added dropwise, and then an aging treatment is performed to obtain an aged mixture;

[0035] Mix silver nitrate, ammonia and water to obtain a silver ammonia solution;

[0036] The silver ammonia solution is added dropwise to the aged mixture, and microwave in-situ reaction is carried out to obtain the silver cluster zeolite.

[0037] In the present invention, unless otherwise specified, the raw materials used are commercially available products in the art.

[0038] The method comprises mixing a sodium hydroxide solution and sodium metaaluminate, dropping silica sol therein, and then performing an aging treatment to obtain an aged mixture.

[0039] In the present invention, the usage ratio of the sodium hydroxide solution to sodium metaaluminate is preferably 3 mL:0.05 g, and the concentration of the sodium hydroxide solution is preferably 20 wt %.

[0040] In the present invention, the usage ratio of the sodium metaaluminate to the silica sol is preferably 0.05 g:12 mL, and the mass percentage of silicon dioxide in the silica sol is preferably 30%.

[0041] In the present invention, a template is preferably added, and the template is preferably tetrapropylammonium hydroxide (TPAOH). The tetrapropylammonium hydroxide is preferably used in the form of a tetrapropylammonium hydroxide solution. The concentration of the tetrapropylammonium hydroxide solution is preferably 40 wt %. The volume ratio of the sodium hydroxide solution to the tetrapropylammonium hydroxide solution is preferably 1:1.

[0042] In the present invention, the temperature of the aging treatment is preferably 90° C., and the time is preferably 16 h. The function of the aging treatment is to form ZSM-5 zeolite crystallites in advance and accelerate the subsequent reaction rate.

[0043] The invention mixes silver nitrate, ammonia water and water to obtain a silver ammonia solution.

[0044] In the present invention, the water is preferably deionized water.

[0045] In the present invention, the silver nitrate is preferably first dissolved in water, and then aqueous ammonia is added dropwise until the solution becomes clear, thereby obtaining the silver ammonia solution. The present invention does not particularly limit the concentration and amount of aqueous ammonia, as long as a clear solution is obtained. In a specific embodiment of the present invention, the mass concentration of aqueous ammonia is 2.5% or 3%.

[0046] After obtaining the silver ammonia solution and the aged mixture, the present invention drips the silver ammonia solution into the aged mixture, performs microwave in-situ reaction, and obtains the silver cluster zeolite.

[0047] In the present invention, the dosage ratio of the silica sol to the silver nitrate used to prepare the silver ammonia solution is preferably 12 mL: 0.025-0.1 g, more preferably 12 mL: 0.05-0.075 g, specifically 12 mL: 0.025 g, 12 mL: 0.05 g, 12 mL: 0.075 g or 12 mL: 0.1 g, and the mass percentage of silicon dioxide in the silica sol is preferably 30%.

[0048] In the present invention, the temperature of the microwave in-situ reaction is preferably 190° C., and the time is preferably 5 minutes.

[0049] In the present invention, the power of the microwave in-situ reaction is preferably 1000W.

[0050] In the present invention, the microwave in-situ reaction is preferably carried out in a microwave digestion instrument.

[0051] In the present invention, after the silver ammonia solution is added dropwise to the aged mixture, stirring and ultrasonication are preferably performed in sequence. The stirring time is preferably 30 minutes, and the ultrasonication time is preferably 10 minutes.

[0052] After the microwave in-situ reaction is completed, the present invention preferably centrifuges and dries the obtained microwave in-situ reaction product in sequence to obtain the silver cluster zeolite.

[0053] In the present invention, the drying temperature is preferably 90° C., and the drying time is preferably 24 hours.

[0054] The present invention also provides a silver cluster zeolite prepared by the preparation method described in the above technical solution, comprising zeolite and silver clusters, wherein the silver clusters are confined within the framework of the zeolite.

[0055] In the present invention, the particle size of the silver clusters (silver nanoparticles) is preferably 2 to 5 nm.

[0056] In the present invention, the loading amount of silver clusters in the silver cluster zeolite is preferably 0.51 to 1.98 wt%, more preferably 1.25 to 1.75 wt%, and most preferably 1.48 wt%.

[0057] The present invention also provides the application of the silver cluster zeolite described in the above technical solution in the field of sterilization.

[0058] In the present invention, the silver cluster zeolite is preferably used to kill Escherichia coli, Staphylococcus aureus or Candida albicans.

[0059] In the present invention, when used, the addition amount of the silver cluster zeolite is preferably 0 to 8 mg / mL, specifically 2, 4, 6 or 8 mg / mL.

[0060] In the present invention, the silver cluster zeolite is preferably recycled, and the number of times of recycling is preferably 3 to 5 times.

[0061] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0062] Figure 1 This is a flow chart of the preparation method of silver cluster zeolite in an embodiment of the present invention.

[0063] Example 1

[0064] Silver cluster zeolite was synthesized in one pot by adding 0.05 g of sodium aluminate to 3 mL of 20 wt% sodium hydroxide solution and 3 mL of 40 wt% tetrapropylammonium hydroxide solution, stirring for 5 min, adding 12 mL of 30% (mass percentage of silica in silica sol) silica sol dropwise, and continuing stirring for 5 min. Then, the mixture was aged at 90°C for 16 h.

[0065] Silver ammonia solutions were prepared by dissolving 0.025 g, 0.050 g, 0.075 g, and 0.100 g of silver nitrate in 1 mL of deionized water and adding ammonia water dropwise until the solution just became clear.

[0066] The silver ammonia solution was added dropwise to the aged mixture, stirred vigorously for 30 minutes, and then sonicated for 10 minutes. The mixture was then placed in a microwave reactor, reacted at 190°C for 5 minutes, centrifuged, and dried at 90°C for 24 hours. The resulting samples were named AGZ-25, AGZ-50, AGZ-75, and AGZ-100. The silver loading mass fraction of AGZ-25 was 0.51%, that of AGZ-50 was 1.03%, that of AGZ-75 was 1.48%, and that of AGZ-100 was 1.98%.

[0067] The XRD results were collected using an X-ray diffractometer (Cu-Kα radiation), such as Figure 2 As shown in the figure, it shows that the addition of silver ammonia solution during the zeolite synthesis process does not affect the crystal structure of the zeolite. At the same time, as the amount of silver added increases, the characteristic peak of the Ag(111) plane at 38.1° gradually becomes more obvious, proving that the silver loading of the zeolite gradually increases with the increase in the amount of silver added.

[0068] The size distribution and element distribution of silver nanoparticles in zeolite were characterized by high-resolution transmission electron microscopy (HRTEM), and STEM characterization was performed as follows. Figure 3 As shown, as the amount of silver ammonia solution added increases, the particle size and number of the formed silver nanoparticles gradually increase. Larger particle sizes reduce the specific surface area of ​​the silver clusters. Fewer silver clusters also result in wasted zeolite. Electron micrographs show that AGZ-50 and AGZ-75 achieve a better balance between number and particle size.

[0069] The particle size distribution of silver clusters in AGZ-75 was analyzed, and the results are as follows: Figure 4 As shown, the particle size Gaussian fitting is 2.98 nm and the average value is 3.22 nm.

[0070] The element distribution analysis diagram of AGZ-75 is as follows Figure 5 As shown, it can be seen that in AGZ-75, the silver element is evenly distributed throughout the entire zeolite.

[0071] Figure 6 This is the TEM spectrum of AGZ-75. From the lattice diffraction fringes, it can be seen that the in situ synthesized silver clusters exhibit a good crystal structure. Based on the lattice spacing of 0.234nm, it can be confirmed that this is the Ag(111) plane.

[0072] Figure 7 This is the XRD spectrum of AGZ-75.

[0073] The concentration of the E. coli solution used in the sterilization rate test was 7.5×10 5 CFU / mL, the cycle sterilization used is 5×10 3 CFU / mL of Escherichia coli in aqueous solution.

[0074] Cyclic sterilization process: 3g of AGZ-75 is added to 100mL of an aqueous solution of E. coli and soaked for 24 hours. The AGZ-75 is then recovered over 24 hours, and 30mg of AGZ-75, known as the primary-recovery zeolite, is removed. The remaining zeolite is then added to the 100mL aqueous solution of E. coli. This cycle is repeated five times to obtain primary-recovery AGZ-75, secondary-recovery AGZ-75, tertiary-recovery AGZ-75, quadruple-recovery AGZ-75, and quintuple-recovery AGZ-75, respectively. The sterilization rate is then tested using the minimum inhibitory concentration (MIC). Sterilization rate testing process: Prepare E. coli culture medium, add 5mL of the culture medium to AGZ-75 at different recovery times, and shake on a shaker at 37°C for 24 hours. After 24 hours, the sterilization rate is calculated using the plate count method.

[0075] Figure 8The sterilization dose-effect curves of different AGZ-75 addition amounts show that the sterilization rate of E. coli is high when the addition amount of AGZ-75 is 6 mg / mL, reaching 99.99%. Figure 9 This is the AGZ-75 cycle sterilization test curve. It can be seen that after five cycles, the zeolite's sterilization rate against E. coli is still above 90%, showing excellent durability and high economic benefits.

[0076] At the same time, the bactericidal rates (E. coli solution) of AGZ-25, AGZ-50 and AGZ-100 were tested. When the equivalent silver addition amounts of AGZ-25, AGZ-50 and AGZ-100 were the same, the bactericidal rates against E. coli were 87.9%, 93.4% and 83.5% of that of AGZ-75 with the equivalent silver addition amount, respectively.

[0077] In summary, the present invention, through the microwave in-situ reaction strategy, achieves uniform distribution of silver nanoparticles within the zeolite. The uniform size and distribution of silver zeolite AGZ-75 demonstrated excellent bactericidal efficacy in bactericidal tests. The silver cluster zeolite maintains its excellent bactericidal efficacy even after repeated recycling.

[0078] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing silver cluster zeolite for sterilization, characterized in that: The following steps are involved: After mixing sodium hydroxide solution and sodium metaaluminate, silica sol is added dropwise, and then an aging treatment is performed to obtain an aged mixture; Mix silver nitrate, ammonia and water to obtain a silver ammonia solution; adding the silver ammonia solution dropwise to the aged mixture and performing microwave in-situ reaction to obtain the silver cluster zeolite; The dosage ratio of the sodium hydroxide solution to sodium metaaluminate is 3 mL:0.05 g, and the concentration of the sodium hydroxide solution is 20 wt %; The ratio of sodium metaaluminate to silica sol is 0.05 g:12 mL, and the mass percentage of silicon dioxide in the silica sol is 30%; The amount ratio of the silica sol to the silver nitrate used to prepare the silver ammonia solution is 12 mL: 0.075 g.

2. The preparation method according to claim 1, characterized in that The aging treatment was performed at a temperature of 90° C. and for 16 hours.

3. The preparation method according to claim 1, characterized in that The temperature of the microwave in-situ reaction is 190° C. and the reaction time is 5 minutes.

4. The preparation method according to claim 1, characterized in that After the silver ammonia solution is added dropwise to the aged mixture, stirring and ultrasonication are performed in sequence. The stirring time is 30 minutes, and the ultrasonication time is 10 minutes.

5. The silver cluster zeolite prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The invention comprises zeolite and silver clusters, wherein the silver clusters are confined within the framework of the zeolite.

6. Use of the silver cluster zeolite according to claim 5 in the preparation of a sterilization product.

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