Silver cluster zeolite as well as preparation method and application thereof

Abstract

The invention provides silver cluster zeolite as well as a preparation method and application thereof, and belongs to the technical field of bactericides. The preparation method comprises the following steps: mixing a sodium hydroxide solution and sodium metaaluminate, dropwise adding silica sol, and then carrying out 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 into the aged mixture, and carrying out microwave in-situ reaction to obtain the silver cluster zeolite. According to the method, seed crystals are synthesized in advance, and high-temperature rapid synthesis of ZSM-5 zeolite is carried out in a microwave in-situ reaction mode, so that the synthesis speed of zeolite is approximate to the generation speed of silver nanoparticles, the silver nanoparticles and a zeolite framework are synthesized synchronously, the size difference of the formed silver nanoparticles is small, and the particle size is uniform. And the silver nanoparticles are uniformly distributed in a framework of the zeolite.

Description

Technical Field

[0001] The 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, posing 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, and they pose a serious threat to human health. Staphylococcus aureus is a Gram-positive bacterium that resides in the nares, skin, and gastrointestinal tract, and frequently invades the human skin, soft tissues, and blood. Escherichia coli is a commensal in the vertebrate intestine and is increasingly involved in various intestinal and extraintestinal infections as an opportunistic pathogen. Candida albicans is an opportunistic yeast that is the main cause of oral candidiasis and denture stomatitis, and severe conditions can even lead to life-threatening systemic infections. Therefore, the development of new fungicides is of great and far-reaching significance to human life.

[0003] As a new type of bactericidal agent, silver nanoparticles have the advantages of high efficiency, broad-spectrum antibacterial, long duration, and low resistance to drug resistance. Therefore, the antibacterial activity of silver nanoparticles is most valuable in the medical and health care fields. The incorporation of AgNPs into hundreds of products has been studied, including surgical and food handling tools, clothing, cosmetics, dental products, catheters and dressings. However, silver nanoparticles still have the disadvantages of being easy to agglomerate and difficult to recycle. The agglomeration phenomenon not only affects the stability and dispersibility of silver nanoparticles, but also may reduce their bactericidal performance. The recycling of silver nanoparticles is also an environmental and economic issue worthy of attention. Since silver is a precious metal, its effective recycling and reuse after use has important economic value. However, nano-scale silver particles are easy to form colloids due to their small size, making them difficult to recycle and the recycling cost high.

[0004] Zeolite is a porous crystalline aluminosilicate found in nature. Low toxicity, high surface area and good stability make zeolite a commonly used loading material. The common method for synthesizing silver nanoparticles in zeolite is ion exchange. The zeolite structure is first synthesized, and then the zeolite is soaked in a silver particle solution to exchange the silver ions for the sodium ions on the zeolite skeleton. The silver ions are then reduced to silver nanoparticles by heating, microwaves, adding reducing agents, etc. The size of the nanoparticles synthesized by this method varies greatly, and the distribution of the nanosilver particles is uneven. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a silver cluster zeolite and a preparation method and application thereof. In the silver cluster zeolite prepared by the present invention, the size difference of silver nanoparticles is small, and the silver nanoparticles are evenly distributed in the framework of the zeolite.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a silver cluster zeolite, comprising the following steps:

[0008] After mixing sodium hydroxide solution and sodium aluminate, adding silica sol dropwise, and then performing aging treatment to obtain an aged mixture;

[0009] Mix silver nitrate, ammonia and water to obtain a silver ammonia solution;

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

[0011] Preferably, the dosage 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 dosage ratio of the sodium aluminate to the silica sol is 0.05 g:12 mL, and the mass percentage of silicon dioxide in the silica sol is 30%.

[0013] Preferably, the usage ratio of the silica sol to the silver nitrate used to prepare 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 the silver nitrate used to prepare the silver ammonia solution is 12mL: 0.05-0.075g.

[0015] Preferably, the aging treatment is carried out at a temperature of 90° C. and for a time of 16 hours.

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

[0017] Preferably, after the silver ammonia solution is added dropwise to the aged mixture, stirring and ultrasonication are sequentially performed, wherein the stirring time is 30 minutes and the ultrasonication time is 10 minutes.

[0018] 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.

[0019] The present invention also provides the application of the silver cluster zeolite described in the above technical solution in the field of sterilization.

[0020] The invention provides a method for preparing a silver cluster zeolite, comprising the following steps: mixing a sodium hydroxide solution and sodium aluminate, dripping 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; dripping the silver ammonia solution into 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 invention synthesizes ZSM-5 zeolite at high temperature and rapidly by pre-synthesizing seed crystals and using microwave in-situ reaction, so that the synthesis speed of zeolite and the generation rate of silver nanoparticles are similar, 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 framework of the zeolite.

[0023] The present invention also provides a silver cluster zeolite prepared by the preparation method described in the above technical solution, which uses the porous structure of the zeolite to limit the silver nanoparticles, so that the silver nanoparticles are evenly dispersed inside the zeolite, so that the silver nanoparticles will not agglomerate. At the same time, because the zeolite as a whole is insoluble in water, it is easy to recycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 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 the embodiment of the present invention;

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

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

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

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

[0031] Figure 8 The bactericidal dose-effect curve of different AGZ-75 addition amounts;

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

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

[0034] After mixing sodium hydroxide solution and sodium aluminate, adding silica sol dropwise, and then performing aging treatment 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 performed to obtain the silver cluster zeolite.

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

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

[0039] In the present invention, the dosage ratio of the sodium hydroxide solution to sodium aluminate 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 dosage ratio of the sodium aluminate 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, it is preferred to further add a template agent, and the template agent 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 40wt%. 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 hours. The function of the aging treatment is to form ZSM-5 zeolite microcrystals 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 dissolved in water first, and then ammonia water is added dropwise until the solution becomes clear to obtain the silver ammonia solution. The present invention has no particular limitation on the concentration and amount of the ammonia water, as long as a clear solution can be obtained. In a specific embodiment of the present invention, the mass concentration of the ammonia water 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 min.

[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 0.51-1.98 wt %, more preferably 1.25-1.75 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 technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part 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 creative work are within the scope of protection of the present invention.

[0062] Figure 1 The flowchart of the preparation method of silver cluster zeolite in the embodiment of the present invention is shown in FIG.

[0063] Example 1

[0064] Silver cluster zeolite was synthesized in one pot from the reactants: 3 mL of 20 wt% sodium hydroxide solution and 3 mL of 40 wt% tetrapropylammonium hydroxide solution were added with 0.05 g of sodium aluminate and stirred for 5 min, 12 mL of 30% (mass percentage of silicon dioxide in the silica sol) of silica sol was added dropwise and stirring was continued for 5 min, and then the mixture was aged at 90°C for 16 h.

[0065] Dissolve 0.025 g, 0.050 g, 0.075 g, and 0.100 g of silver nitrate in 1 mL of deionized water, and add ammonia water dropwise until the solution becomes clear to prepare a silver ammonia solution.

[0066] The silver ammonia solution was added dropwise to the aged mixture, stirred vigorously for 30 minutes, ultrasonicated for 10 minutes, placed in a microwave reactor, reacted at 190°C for 5 minutes, centrifuged, and dried at 90°C for 24 hours. The samples were named AGZ-25, AGZ-50, AGZ-75, and AGZ-100, of which the silver loading mass fraction of AGZ-25 was 0.51%, the silver loading mass fraction of AGZ-50 was 1.03%, the silver loading mass fraction of AGZ-75 was 1.48%, and the silver loading mass fraction 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, it shows that adding silver ammonia solution during the zeolite synthesis process will not affect the crystal structure of the zeolite. At the same time, as the amount of silver added increases, it can be seen that the characteristic peak of the Ag (111) plane at 38.1° gradually becomes obvious, proving that as the amount of silver added increases, the silver loading of the zeolite also gradually increases.

[0068] High-resolution transmission electron microscopy (HRTEM) was used to characterize the size distribution and elemental distribution of silver nanoparticles in zeolite. STEM characterization was performed as Figure 3 As shown, it shows that with the increase of the amount of silver ammonia solution added, the particle size and number of the formed silver nanoparticles gradually increase, and the larger particle size reduces the specific surface area of ​​the silver clusters. Fewer silver clusters will also cause waste of zeolite. It can be seen from the electron microscope that AGZ-50 and AGZ-75 can better achieve a balance between quantity and particle size.

[0069] The particle size distribution of silver clusters in AGZ-75 was analyzed. Figure 4 As shown, it can be seen that the particle size Gaussian fitting is 2.98nm and the average value is 3.22nm.

[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 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 uses 5×10 3 CFU / mL of Escherichia coli in aqueous solution.

[0074] Cyclic sterilization process: Take 3g AGZ-75 and add it to 100mL E. coli aqueous solution and soak it for 24h. Recover AGZ-75 in 24h, take out 30mg AGZ-75, which is called the first-recovery zeolite, and put the remaining zeolite into 100mL E. coli aqueous solution again. Cycle 5 times to get the first-recovery AGZ-75, the second-recovery AGZ-75, the third-recovery AGZ-75, the fourth-recovery AGZ-75 and the fifth-recovery AGZ-75. Test the sterilization rate according to the minimum inhibitory concentration. Sterilization rate test process: Prepare E. coli culture solution, take 5mL E. coli culture solution and add AGZ-75 with different recovery times, shake it at 37℃ for 24h, and calculate the sterilization rate by plate counting method after 24h.

[0075] Figure 8The bactericidal dose-effect curves of different AGZ-75 addition amounts show that the bactericidal rate of Escherichia coli is high when the addition amount of AGZ-75 is 6 mg / mL, reaching 99.99%; Fig. 9 This is the AGZ-75 cycle sterilization test curve. It can be seen that after five cycles, the sterilization rate of the zeolite against Escherichia 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 can achieve uniform distribution of silver nanoparticles inside zeolite through the strategy of microwave in-situ reaction, and the silver zeolite AGZ-75 with uniform size and distribution has shown good bactericidal effect in the bactericidal test. Through multiple cycles of recycling and use, the silver cluster zeolite can still show good bactericidal effect.

[0078] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing silver cluster zeolite, characterized in that: The following steps are involved: After mixing sodium hydroxide solution and sodium aluminate, adding silica sol dropwise, and then performing aging treatment to obtain an aged mixture; Mix silver nitrate, ammonia and water to obtain a silver ammonia solution; The silver ammonia solution is added dropwise to the aged mixture, and microwave in-situ reaction is performed to obtain the silver cluster zeolite.

2. The preparation method according to claim 1, characterized in that: The dosage 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 %.

3. The preparation method according to claim 1 or 2, characterized in that: The dosage ratio of the sodium aluminate to the silica sol is 0.05 g:12 mL, and the mass percentage of silicon dioxide in the silica sol is 30%.

4. The preparation method according to claim 1, characterized in that: The dosage ratio of the silica sol to the 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%.

5. The preparation method according to claim 4, characterized in that: The dosage ratio of the silica sol to the silver nitrate used to prepare the silver ammonia solution is 12mL: 0.05-0.075g.

6. The preparation method according to claim 1, characterized in that: The temperature of the aging treatment is 90° C. and the time is 16 hours.

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

8. 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, wherein the stirring time is 30 minutes and the ultrasonication time is 10 minutes.

9. The silver cluster zeolite obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The invention comprises zeolite and silver clusters, wherein the silver clusters are confined within the framework of the zeolite.

10. Use of the silver cluster zeolite according to claim 9 in the field of sterilization.

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