Bark-like nano zinc oxide and preparation method thereof

Abstract

The present invention relates to a bark-like nano zinc oxide and a preparation method thereof, belonging to the technical field of liquid-phase synthesis of nano zinc oxide. The present invention prepares a nano zinc oxide material with a bark-like microscopic morphology by regulating the liquid-phase environment, reaction thermodynamics and kinetic parameters. The material has obvious layering and pore characteristics, giving the material significantly enhanced physical and chemical properties, such as a significant increase in the BET specific surface area. At the same time, the high porosity and the nano-grain boundary effect work synergistically, enabling it to efficiently generate active oxygen species and zinc ion antibacterial active species, thereby significantly improving the antibacterial performance of the material. Antibacterial experiments have shown that the antibacterial rate of the material against Escherichia coli and Staphylococcus aureus exceeds 99.9%, and the antibacterial rate against Candida albicans exceeds 99.0%. The material shows application potential in the fields of medical dressings, antibacterial textiles and water purification.

Description

Technical Field

[0001] The invention belongs to the technical field of liquid phase synthesis of nano zinc oxide and relates to bark-shaped nano zinc oxide and a preparation method thereof. Background Art

[0002] Nano-zinc oxide is a new type of multifunctional inorganic material with unique physical and chemical properties, such as excellent photocatalytic activity and nanoscale effects. It has broad application prospects in the fields of antibacterial, photocatalysis, sensors, etc. At present, ZnO NPs have excellent antibacterial properties against both bacteria and fungi. Their antibacterial properties can be further improved by adjusting their particle morphology, particle size and other parameters, as well as surface modification. At present, research on the antibacterial mechanism of zinc oxide nanoparticles has also made progress, mainly focusing on the generation mechanism of reactive oxygen species. However, nano-zinc oxide obtained by traditional preparation methods such as hydrothermal method and chemical vapor deposition often faces problems such as particle agglomeration and uneven size. In addition, the controllability of its morphology is poor and the specific surface area is limited, resulting in insufficient active sites, which limits the further improvement of its antibacterial properties.

[0003] The nano-zinc oxide-coated nano-silver antibacterial composite material prepared by patent CN111185170A has a 99% sterilization rate against Staphylococcus aureus, but the high cost and potential biological toxicity of nano-silver limit its application in industrial production and biomedical fields.

[0004] Patent CN108439458A uses hexadecyltrimethylammonium bromide as a template and adopts a hydrothermal method to synthesize two-dimensional sheet-like nano-zinc oxide; Patent CN103560238A uses an aqueous solution of zinc nitrate and hexamethylenetetramine as a precursor and a quaternary ammonium salt as a cationic surfactant. However, most quaternary ammonium salts such as hexadecyltrimethylammonium bromide and hexamethylenetetramine are toxic and harmful chemicals that will pollute the environment.

[0005] Therefore, it is of great significance to develop a method for preparing nano-ZnO with specific morphology and excellent antibacterial properties. Summary of the Invention

[0006] In response to the current problems of insufficient antibacterial performance of zinc oxide and poor controllability of morphology and structure, the present invention proposes a bark-like nano zinc oxide and a preparation method thereof. The preparation method of the present invention has the characteristics of simple operation, low cost and mass production. The prepared nano zinc oxide has good dispersibility and excellent antibacterial properties.

[0007] The purpose of the present invention can be achieved through the following technical solutions:

[0008] The invention discloses a bark-like nano zinc oxide, which is formed by interweaving or stacking nano zinc oxide fibers with a length of 10 to 1000 nm and a diameter of 1 to 10 nm to form a continuous sheet structure and then stacking them.

[0009] Furthermore, the bark-shaped nano zinc oxide has a length of 0.1 μm to 1 μm, a width of 0.1 μm to 0.8 μm, and an aspect ratio of 1:1 to 10:1.

[0010] Furthermore, the gap size between the nano zinc oxide fibers or layers is 1 nm to 200 nm.

[0011] A method for preparing bark-like nano zinc oxide, the specific steps of the preparation method are as follows:

[0012] S1: dissolving a zinc precursor and an alkali in a polyol to form a zinc precursor solution and an alkali solution, respectively;

[0013] S2: Heat both solutions to 75°C~85°C;

[0014] S3: Add deionized water to the zinc precursor solution, pour the alkaline solution into the zinc precursor solution, and continue heating and stirring for 1-5 h;

[0015] S4: The product after the reaction is centrifuged, washed, and dried to obtain bark-like nano zinc oxide.

[0016] Furthermore, the molar ratio of the zinc precursor to the base is 1:1 to 1:3.

[0017] Furthermore, the molar concentration of the zinc precursor solution is 0.01 mol / L to 2.5 mol / L, and the molar concentration of the alkaline solution is 0.01 mol / L to 7.5 mol / L.

[0018] Furthermore, the zinc precursor is one or more of zinc chloride, zinc nitrate hexahydrate and zinc acetate dihydrate.

[0019] Furthermore, the base is one or more of sodium hydroxide and potassium hydroxide.

[0020] Furthermore, the polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol and glycerol.

[0021] Furthermore, the volume ratio of the deionized water to the polyol is 1:10 to 1:100.

[0022] The present invention adopts a polyol-water two-phase regulation mechanism to synergistically control the nucleation and growth of nano zinc oxide. Through the synergistic effect of deionized water and polyols, a unique microemulsion reaction environment is constructed: polyols as solvents not only provide hydroxyl coordination sites to promote the uniform dispersion of zinc ions, but also their volume ratio with water accurately controls the nucleation rate, forming an "instantaneous burst nucleation-slow growth" crystallization process, ensuring that the nanofibers self-assemble to form a bark-like hierarchical structure. At the same time, the present invention also optimizes the reaction conditions based on thermodynamic reactions. The setting of the reaction temperature ensures that zinc hydroxide is dehydrated and converted into zinc oxide while avoiding the Oswald ripening effect caused by high temperature that destroys the fine morphology. In addition, the present invention also achieves controllable modulation of nano-grain size and porosity through the gradient design of zinc precursor concentration and alkali concentration, and by adjusting the supersaturation of the solution.

[0023] The unique bark-like morphology of the nano-zinc oxide prepared by the present invention imparts significant functional advantages. It exhibits a three-dimensional network of coexisting micron-scale sheet units and nano-scale pores, significantly increasing the BET specific surface area of ​​the nano-zinc oxide. The hierarchical pore structure produces an "edge effect" that significantly increases the dissolution rate of zinc ions. Furthermore, the bark-like nano-zinc oxide effectively enhances the ROS quantum yield under photocatalysis. When combined with textile fibers, the crown-like morphology forms a mechanical bond with the fibers, significantly enhancing interfacial interactions. The antibacterial rate remains high even after multiple washes, far exceeding that of conventional nano-zinc oxide coatings.

[0024] The process flow of the present invention also has the following advantages: the three-step dissolution-mixing-crystallization process shortens the reaction time by more than 60% compared with the traditional hydrothermal method, and through a simple temperature-time dual-control strategy, it achieves a directional transformation of the morphology from nanoparticles to micron bark; the use of cheap polyols instead of organic templates, combined with mother liquor recycling technology, significantly reduces the cost of a single synthesis.

[0025] Beneficial effects of the present invention:

[0026] The bark-like nano-zinc oxide prepared in this invention possesses a multi-level micro-nano composite structure. Its open pore network and nanoscale rough surface synergistically create a high-surface-area reaction interface, effectively promoting the explosive generation of reactive oxygen species and accelerating the controlled release of zinc ions, forming a structurally enhanced antibacterial mechanism. Experiments have confirmed that this material exhibits excellent broad-spectrum antibacterial activity against Gram-negative and Gram-positive bacteria, as well as fungi, suggesting broad application prospects in the field of antibacterial materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0028] Figure 1 This is a low-magnification scanning electron microscope image of the nano zinc oxide prepared in Example 1;

[0029] Figure 2 This is a high-magnification scanning electron microscope image of the nano zinc oxide prepared in Example 1;

[0030] Figure 3 This is the X-ray diffraction pattern of the nano zinc oxide prepared in Example 1. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and preferred embodiments.

[0032] Example 1

[0033] 1.634g of zinc acetate dihydrate and 0.596g of sodium hydroxide were weighed and dissolved in 30mL of ethylene glycol to form a zinc precursor solution and an alkaline solution, respectively. Both were then heated to 75°C. 2mL of deionized water was added to the zinc precursor solution, and the sodium hydroxide solution was poured into the zinc precursor solution. The constant temperature heating device was set at 600r / min and the temperature was 75°C. The reaction was carried out for 2 hours to obtain a white nano-zinc oxide suspension. The product was centrifuged and the separated nano-zinc oxide was washed three times with deionized water and anhydrous ethanol, respectively, and then placed in an oven at 80°C for 2 hours to obtain bark-like nano-zinc oxide.

[0034] Example 2

[0035] 3.268g of zinc acetate dihydrate and 1.672g of potassium hydroxide were weighed and dissolved in 30mL of 1,4-butanediol to form a zinc precursor solution and an alkaline solution, respectively. Both were then heated to 75°C. 1mL of deionized water was added to the zinc precursor solution, and the potassium hydroxide solution was poured into the zinc precursor solution. The constant temperature heating device was set at 700r / min and the temperature was 75°C. The reaction was carried out for 3h to obtain a white nano-zinc oxide suspension. The product was centrifuged and the separated nano-zinc oxide was washed three times with deionized water and anhydrous ethanol, respectively, and then placed in an oven at 80°C for 2h to obtain bark-like nano-zinc oxide.

[0036] Example 3

[0037] 6.646g of zinc nitrate hexahydrate and 2.6808g of sodium hydroxide were weighed and dissolved in 30mL of glycerol to form a zinc precursor solution and an alkaline solution, respectively. Both were then heated to 85°C. 3mL of deionized water was added to the zinc precursor solution, and the sodium hydroxide solution was poured into the zinc precursor solution. The constant temperature heating device was set at 700r / min and the temperature was 85°C. The reaction was continued for 2.5 hours to obtain a white nano-zinc oxide suspension. The product was centrifuged and the separated nano-zinc oxide was washed three times with deionized water and anhydrous ethanol, respectively, and then dried in an oven at 80°C for 2 hours to obtain a bark-like nano-zinc oxide.

[0038] Example 4

[0039] 0.252g of zinc chloride and 0.147g of sodium hydroxide were weighed and dissolved in 30mL of ethylene glycol to form a zinc precursor solution and an alkaline solution, respectively. Both were then heated to 75°C. 3mL of deionized water was added to the zinc precursor solution, and the sodium hydroxide solution was poured into the zinc precursor solution. The constant temperature heating device was set at 500r / min and the temperature was 75°C. The reaction was carried out for 1.5 hours to obtain a white nano-zinc oxide suspension. The product was centrifuged and the separated nano-zinc oxide was washed three times with deionized water and anhydrous ethanol, respectively, and then placed in an oven to dry at 80°C for 2 hours to obtain bark-like nano-zinc oxide.

[0040] Performance Testing

[0041] The specific surface area and porosity of the bark-like nano zinc oxide prepared in Example 1 were tested. The test results are shown in Table 1:

[0042] Table 1

[0043] The antibacterial effect of the bark-like nano zinc oxide prepared in Examples 1 to 4 was tested according to Appendix A of GB / T 21510-2008, Test Methods for Antibacterial Performance of Nano-inorganic Materials, Test Method for Antibacterial Performance of Powders: Oscillation Method. The killing rates of the bark-like nano zinc oxide against Escherichia coli, Staphylococcus aureus, and Candida albicans were measured, as shown in Table 2:

[0044] Table 2

[0045] The above experimental data show that the bark-like nano zinc oxide material prepared by the present invention has a good antibacterial effect on Gram-positive bacteria, Gram-negative bacteria and fungi.

[0046] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A bark-like nano zinc oxide, characterized in that: The bark-like nano zinc oxide is formed by interweaving or stacking nano zinc oxide fibers with a length of 10 to 1000 nm and a diameter of 1 to 10 nm to form a continuous sheet structure, which is then stacked. The bark-like nano zinc oxide has a length of 0.1 μm to 1 μm, a width of 0.1 μm to 0.8 μm, and an aspect ratio of 1:1 to 10:

1. The specific steps of the bark-like nano zinc oxide preparation method are as follows: S1: dissolving a zinc precursor and an alkali in a polyol to form a zinc precursor solution and an alkali solution, respectively; S2: Heat both solutions to 75°C~85°C; S3: Add deionized water to the zinc precursor solution, pour the alkaline solution into the zinc precursor solution, and continue heating and stirring for 1-5 h; S4: centrifugally separating, washing, and drying the reaction product to obtain bark-like nano zinc oxide; Wherein, the volume ratio of the deionized water to the polyol is 1:10 to 1:

100.

2. The bark-like nano zinc oxide according to claim 1, characterized in that: The size of the gap between the nano zinc oxide fibers or layers is 1 nm to 200 nm.

3. The method for preparing bark-like nano zinc oxide according to claim 1, wherein: The molar ratio of the zinc precursor to the base is 1:1 to 1:

3.

4. The method for preparing bark-like nano zinc oxide according to claim 1, wherein: The molar concentration of the zinc precursor solution is 0.01 mol / L to 2.5 mol / L, and the molar concentration of the alkaline solution is 0.01 mol / L to 7.5 mol / L.

5. The method for preparing bark-like nano zinc oxide according to claim 1, wherein: The zinc precursor is one or more of zinc chloride, zinc nitrate hexahydrate and zinc acetate dihydrate.

6. The method for preparing bark-like nano zinc oxide according to claim 1, wherein: The alkali is one or more of sodium hydroxide and potassium hydroxide.

7. The method for preparing bark-like nano zinc oxide according to claim 1, wherein: The polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol and glycerol.

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