Bark-shaped nano zinc oxide and preparation method thereof

Abstract

The invention relates to bark-like nano-zinc oxide and a preparation method thereof, and belongs to the technical field of liquid-phase synthesis of nano-zinc oxide. According to the invention, the nano zinc oxide material with bark-like microstructure is prepared by regulating and controlling the liquid phase environment and the thermodynamic and kinetic parameters of the reaction. The material has obvious layering sense and pore characteristics, the material is endowed with significantly enhanced physicochemical characteristics, for example, the BET specific surface area is significantly increased, and meanwhile, the high porosity and the nanocrystal boundary effect have a synergistic effect, so that active oxygen species and zinc ion antibacterial active species can be efficiently generated, and the antibacterial performance of the material is significantly improved. An antibacterial experiment shows that the antibacterial rate of the material to escherichia coli and staphylococcus aureus exceeds 99.9%, and the antibacterial rate of the material to candida albicans exceeds 99.0%. The material has application potential in the fields of medical dressings, antibacterial textiles, water purification and the like.

Description

Technical Field

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

[0002] Nano zinc oxide is a new type of inorganic material with multiple functions, having unique physical and chemical properties, such as excellent photocatalytic activity, nano-scale effect, etc., and 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, and their antibacterial performance can be further improved by adjusting parameters such as their particle morphology, particle size, and surface modification methods. 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, the nano zinc oxide obtained by traditional preparation methods such as hydrothermal method and chemical vapor deposition often faces problems such as particle agglomeration, uneven size, poor controllability of its morphology, and limited specific surface area, resulting in insufficient active sites and restricting the further improvement of its antibacterial performance.

[0003] The nano zinc oxide-coated nano silver antibacterial composite material prepared in Patent CN111185170A has a 99% bactericidal 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 cetyltrimethylammonium bromide as a template and synthesizes two-dimensional sheet-like nano zinc oxide by a hydrothermal method; Patent CN103560238A uses an aqueous solution of zinc nitrate and hexamethylenetetramine as a precursor and a quaternary ammonium salt as a cationic surfactant, but most quaternary ammonium salts such as cetyltrimethylammonium bromide and hexamethylenetetramine are toxic and harmful chemical substances, which will cause environmental pollution.

[0005] Therefore, it is of great significance to develop a preparation method of nano zinc oxide with a specific morphology and excellent antibacterial performance. Summary of the Invention

[0006] Aiming at the problems of insufficient antibacterial performance and poor controllability of the morphology and structure of zinc oxide at present, 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 batch production, and the prepared nano zinc oxide has good dispersibility and excellent antibacterial performance.

[0007] The object of the present invention can be achieved by the following technical solutions: A bark-like nano zinc oxide, wherein the bark-like nano zinc oxide is formed by interweaving and connecting or stacking nano zinc oxide fibers with a length of 10 - 1000 nm and a diameter of 1 - 10 nm to form a continuous lamellar structure and then laminating them.

[0008] Further, the bark-like nano zinc oxide has a length of 0.1 μm - 1 μm, a width of 0.1 μm - 0.8 μm, and an aspect ratio of 1:1 - 10:1.

[0009] Further, the gap size between the nano zinc oxide fibers or layers is 1 nm - 200 nm.

[0010] A preparation method of bark-like nano zinc oxide, the specific steps of the preparation method are as follows. S1: Dissolve the zinc precursor and the base in polyol respectively to form a zinc precursor solution and a base solution. S2: Heat both solutions to 75 °C - 85 °C. S3: Add deionized water to the zinc precursor solution, pour the base solution into the zinc precursor solution, and continue heating and stirring for 1 - 5 h. S4: Centrifuge, wash, and dry the reaction product to obtain bark-like nano zinc oxide.

[0011] Further, the molar ratio of the zinc precursor to the base is 1:1 - 1:3.

[0012] Further, the molar concentration of the zinc precursor solution is 0.01 mol / L - 2.5 mol / L, and the molar concentration of the base solution is 0.01 mol / L - 7.5 mol / L.

[0013] Further, the zinc precursor is one or more of zinc chloride, zinc nitrate hexahydrate, and zinc acetate dihydrate.

[0014] Further, the base is one or more of sodium hydroxide and potassium hydroxide.

[0015] Further, the polyol is one or more of ethylene glycol, propylene glycol, 1,4-butanediol, and glycerol.

[0016] Further, the volume ratio of the deionized water to the polyol is 1:10 - 1:100.

[0017] The present invention adopts a polyol-water biphasic regulation mechanism to synergistically control the nucleation and growth of nano-zinc oxide. Through the synergistic effect of deionized water and polyol, a unique microemulsion reaction environment is constructed: the polyol, as a solvent, not only provides hydroxyl coordination sites to promote the uniform dispersion of zinc ions, but also precisely regulates the nucleation rate through its volume ratio with water, forming a crystallization process of "instantaneous burst nucleation - slow growth" to ensure the self-assembly of nanofibers to form a bark-like hierarchical structure. At the same time, the present invention also optimizes the reaction conditions based on the thermodynamic reaction. The setting of the reaction temperature ensures the dehydration conversion of zinc hydroxide to zinc oxide while avoiding the Ostwald ripening effect caused by high temperature from damaging the fine morphology. In addition, the present invention also realizes the controllable modulation of the nano-crystallite size and porosity through the gradient design of the zinc precursor concentration and the alkali concentration, and by adjusting the solution supersaturation.

[0018] The special bark-like morphology of the nano-zinc oxide prepared by the present invention endows it with great functional advantages. It exhibits a three-dimensional network with the coexistence of micron-scale flaky units and nano-scale pores, which significantly increases the BET specific surface area of the nano-zinc oxide. The hierarchical pore structure generates an "edge effect", which significantly increases the dissolution rate of zinc ions. At the same time, the ROS quantum yield of the bark-like nano-zinc oxide is effectively increased under photocatalysis. When combined with fabric fibers, the tree-like morphology forms a mechanical lock with the fabric fibers, and the interfacial interaction is significantly strengthened. The antibacterial rate remains at a high level after multiple washes, far higher than that of traditional nano-zinc oxide coatings.

[0019] The technological process of the present invention also has the following advantages: The three-step process of dissolution - mixing - crystallization shortens the reaction time by more than 60% compared with the traditional hydrothermal method. Through a simple temperature-time dual-control strategy, the morphology is directionally transformed from nano-particles to micron-scale bark; cheap polyols are used to replace organic templating agents, and combined with the mother liquor recycling technology, the single synthesis cost is significantly reduced.

[0020] The beneficial effects of the present invention: The bark-like nano-zinc oxide prepared by the present invention has a micro-nano composite multi-level structure. Its open pore network and nano-scale rough surface synergistically construct a high specific surface area reaction interface, effectively promoting the explosive generation of reactive oxygen species and accelerating the controllable slow release of zinc ions, forming a structure-enhanced antibacterial mechanism. Experiments have confirmed that this material exhibits excellent broad-spectrum antibacterial activity against Gram-negative bacteria, Gram-positive bacteria, and fungi, and has broad application prospects in the field of antibacterial materials. Brief Description of the Drawings

[0021] For the convenience of those skilled in the art to understand, the present invention will be further described below in conjunction with the accompanying drawings.

[0022] Figure 1 It is a low-magnification scanning electron micrograph of the nano-zinc oxide prepared in Example 1; Figure 2High-magnification scanning electron micrograph of the nano-zinc oxide prepared in Example 1; Figure 3 X-ray diffraction pattern of the nano-zinc oxide prepared in Example 1. Detailed implementation manners

[0023] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation manners, structures, features and their effects according to the present invention as follows.

[0024] Example 1 Weigh 1.634 g of zinc acetate dihydrate and 0.596 g of sodium hydroxide, and dissolve them in 30 mL of ethylene glycol respectively to form a zinc precursor solution and an alkali solution. Subsequently, both are heated to 75 °C. Add 2 mL of deionized water to the zinc precursor solution, pour the sodium hydroxide solution into the zinc precursor solution, the rotational speed of the constant-temperature heating device is 600 r / min, the temperature is 75 °C, react for 2 h to obtain a white nano-zinc oxide suspension. Centrifuge the product, wash the separated nano-zinc oxide with deionized water and absolute ethanol three times respectively, and then place it in an oven at 80 °C for drying for 2 h to obtain bark-like nano-zinc oxide.

[0025] Example 2 Weigh 3.268 g of zinc acetate dihydrate and 1.672 g of potassium hydroxide, and dissolve them in 30 mL of 1,4-butanediol respectively to form a zinc precursor solution and an alkali solution. Subsequently, both are heated to 75 °C. Add 1 mL of deionized water to the zinc precursor solution, pour the potassium hydroxide solution into the zinc precursor solution, the rotational speed of the constant-temperature heating device is 700 r / min, the temperature is 75 °C, react for 3 h to obtain a white nano-zinc oxide suspension. Centrifuge the product, wash the separated nano-zinc oxide with deionized water and absolute ethanol three times respectively, and then place it in an oven at 80 °C for drying for 2 h to obtain bark-like nano-zinc oxide.

[0026] Example 3 Weigh 6.646 g of zinc nitrate hexahydrate and 2.6808 g of sodium hydroxide, and dissolve them in 30 mL of glycerol respectively to form a zinc precursor solution and an alkali solution. Subsequently, both are heated to 85 °C. Add 3 mL of deionized water to the zinc precursor solution, pour the sodium hydroxide solution into the zinc precursor solution, the rotational speed of the constant-temperature heating device is 700 r / min, the temperature is 85 °C, react for 2.5 h to obtain a white nano-zinc oxide suspension. Centrifuge the product, wash the separated nano-zinc oxide with deionized water and absolute ethanol three times respectively, and then place it in an oven at 80 °C for drying for 2 h to obtain bark-like nano-zinc oxide.

[0027] Example 4 Weigh 0.252 g of zinc chloride and 0.147 g of sodium hydroxide, and dissolve them separately in 30 mL of ethylene glycol to form a zinc precursor solution and an alkali solution. Subsequently, both are heated to 75 °C. Add 3 mL of deionized water to the zinc precursor solution, and pour the sodium hydroxide solution into the zinc precursor solution. The constant-temperature heating device rotates at a speed of 500 r / min and the temperature is 75 °C. React for 1.5 h to obtain a white nano-zinc oxide suspension. Centrifuge the product, wash the separated nano-zinc oxide with deionized water and absolute ethanol three times respectively, and then place it in an oven at 80 °C for drying for 2 h to obtain bark-like nano-zinc oxide.

[0028] Performance Test Perform specific surface area and porosity tests on the bark-like nano-zinc oxide prepared in Example 1. The test results are shown in Table 1: Table 1 Perform antibacterial effect tests on the bark-like nano-zinc oxide prepared in Examples 1 to 4. Refer to Appendix A of GB / T 21510-2008 Test Method for Antibacterial Properties of Nano-inorganic Materials - Powder Antibacterial Property Test Method: Oscillation Method. The killing rates of the prepared bark-like nano-zinc oxide against Escherichia coli, Staphylococcus aureus and Candida albicans are shown in Table 2: Table 2 The above experimental data show that the bark-like nano-zinc oxide material prepared by the present invention has good antibacterial effects against Gram-positive bacteria, Gram-negative bacteria and fungi.

[0029] The above is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention still fall 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.

2. The bark-like nano zinc oxide according to claim 1, characterized in that: 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.

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

4. A method for preparing bark-like nano zinc oxide according to any one of claims 1 to 3, characterized in that: The specific steps of the preparation method are as follows: S1: dissolving a zinc precursor and a base in a polyol to form a zinc precursor solution and a base solution respectively; S2: Heat both solutions to 75 ℃~85 ℃; 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 to 5 hours; S4: The product after the reaction is separated by centrifugation, washed and dried to obtain bark-like nano zinc oxide.

5. The method for preparing bark-like nano zinc oxide according to claim 4, characterized in that: The molar ratio of the zinc precursor to the base is 1:1 to 1:

3.

6. The method for preparing bark-like nano zinc oxide according to claim 4, characterized in that: 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.

7. The method for preparing bark-like nano zinc oxide according to claim 4, characterized in that: The zinc precursor is one or more of zinc chloride, zinc nitrate hexahydrate and zinc acetate dihydrate.

8. The method for preparing bark-like nano zinc oxide according to claim 4, characterized in that: The alkali is one or more of sodium hydroxide and potassium hydroxide.

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

10. The method for preparing bark-like nano zinc oxide according to claim 4, characterized in that: The volume ratio of the deionized water to the polyol is 1:10 to 1:100.

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