Zinc oxide / metal antibacterial powder and method for preparing the same

Abstract

The application relates to the technical field of antibacterial powder and discloses a preparation method of zinc oxide / metal antibacterial powder, which comprises the following steps: firstly, preparing a zinc salt aqueous solution with a concentration of 0.1-2 mol / L; secondly, preparing an alkali metal hydroxide aqueous solution with a concentration of 0.1-4 mol / L; thirdly, adding an ultrafine metal inner core into the zinc salt aqueous solution and heating to 60-90 DEG C; fourthly, adding a certain amount of the hydroxide aqueous solution, so that the molar ratio of the hydroxide to the zinc salt in the mixed solution is 1:2-1:4; and fifthly, stirring for 20-180 minutes, filtering and drying to obtain the zinc oxide / metal antibacterial powder. The application further discloses the microstructure of the zinc oxide / metal antibacterial powder prepared by the above method. The low-temperature preparation method can make the nano zinc oxide form a semiconductor-metal interface and improve the antibacterial performance.

Description

Technical Field

[0001] This invention relates to the field of antibacterial powder technology, and in particular to a zinc oxide / metal antibacterial powder and its preparation method. Background Technology

[0002] Nano zinc oxide is a novel, environmentally friendly, and multifunctional material with excellent properties in magnetism, optics, electricity, sensitivity, antibacterial disinfection, and ultraviolet shielding.

[0003] It is non-toxic, odorless, non-irritating to the skin, and has good thermal stability. It can be used as a topical drug for the skin, as well as a sunscreen in cosmetics to prevent ultraviolet damage and to have antibacterial and deodorizing properties. It can be used to produce deodorizing, antibacterial, and UV-resistant fibers, and to manufacture surgical gowns, nurses' uniforms, underwear, outerwear, shoes, hats, socks, etc. It can also be added to organic materials such as coatings to make antibacterial boards, coatings, etc.

[0004] Currently, doping or modification methods are often used to improve the antibacterial activity of nano zinc oxide. For example, the Chinese invention patent (publication number CN112499664A) proposes a method of doping cuprous oxide, which can significantly improve its antibacterial activity under light conditions. However, cuprous oxide has poor stability and is easily oxidized to copper oxide in the air, resulting in a short service life.

[0005] Chinese invention patent (publication number CN112320835A) discloses a method for preparing tungsten-doped nano zinc oxide, which requires high-temperature calcination, causing the nano powder to easily sinter and agglomerate.

[0006] Chinese invention patent (publication number 113412841A) discloses a zinc oxide nanomaterial modified with 4-mercaptophenylboronic acid and its preparation method. It was found that it has significantly enhanced antibacterial properties. However, organically modified zinc oxide, such as that used in ceramic products fired at high temperatures, loses its properties because the modified layer is burned off at high temperatures.

[0007] There are many existing methods for preparing nano-zinc oxide, including one-step and two-step methods. One-step methods, such as laser methods, mechanical ball milling, hydrothermal methods, spray pyrolysis, and chemical vapor deposition, require complex mechanical equipment and are costly. Two-step methods include chemical precipitation, emulsion or microemulsion methods, colloidal chemistry methods, sol-gel methods, solid-phase chemical reaction methods, thermal explosion methods, and critical drying methods. These methods typically form zinc hydroxide, zinc carbonate, etc., in the first step, followed by high-temperature sintering, which can easily cause agglomeration and requires dispersion processes.

[0008] Chinese invention patent (publication number CN112573560A) discloses a method for preparing highly dispersed zinc oxide, which is carried out in four steps. Under hydrothermal reaction conditions, 1,3,5-tris(1-triazolyl-methylene)-2,4,6-trimethylbenzene and 5-(1-tetraazole)isophthalic acid are added in the first two steps, respectively, and then the mixture is calcined at high temperature. The process is complex and the cost is high.

[0009] Chinese invention patent (publication number CN112777627A) discloses a method for preparing nano zinc oxide, which uses a V-type microchannel reactor to prepare zinc hydroxide and then calcines it. However, the yield is limited and the energy consumption is high.

[0010] Chinese invention patent (publication number CN112266010A) discloses a zinc oxide production process, including the following steps: crushing zinc ingots to obtain zinc blocks, grinding the zinc blocks, heating and stirring zinc powder, adding deionized water to the high-temperature zinc powder, then adding sulfuric acid to the zinc powder aqueous solution to obtain zinc sulfate, drying the zinc sulfate and adding it to a container, then adding sodium carbonate to the container to react and obtain zinc carbonate, washing the zinc carbonate with water, then drying it, calcining it at 400°C, hammering it during the calcination process to obtain zinc oxide, ball milling, and finally obtaining zinc oxide. The process is relatively complex, requires high-temperature treatment, and has high energy consumption. Summary of the Invention

[0011] The purpose of this invention is to solve the above-mentioned problems and provide a zinc oxide / metal antibacterial powder and its preparation method. By using a low-temperature preparation method, nano-zinc oxide forms a semiconductor-metal interface, thereby improving its antibacterial properties.

[0012] The technical solution adopted in this invention is: A zinc oxide / metal antibacterial powder, characterized in that it comprises an ultrafine metal core, on which nano-zinc oxide is grown in various directions to form a fluffy structure, wherein the ultrafine metal core is one of zinc, copper, and aluminum, and its particle size is 20-500 nm; the size of the nano-zinc oxide is 10-2000 nm, the mass ratio of the ultrafine metal core to zinc oxide is 9:1-1:99, and a semiconductor-metal interface is formed between the zinc oxide and the ultrafine metal core.

[0013] Furthermore, the nano zinc oxide is in the form of flakes, with a thickness of 10-100 nm.

[0014] Furthermore, the nano zinc oxide is fibrous, with a diameter of 10-80 nm and a length of 200-2000 nm.

[0015] Furthermore, the nano zinc oxide is rod-shaped, with a diameter of 30-200 nm and a length of 100-2000 nm.

[0016] Furthermore, the smallest surface of the nano-zinc oxide is in contact with the ultrafine metal core.

[0017] A method for preparing zinc oxide / metal antibacterial powder, characterized by comprising the following steps: Step (1) Prepare a zinc salt aqueous solution with a concentration of 0.1-2 mol / L, wherein the zinc salt is one or more of zinc chloride, zinc sulfate, and zinc nitrate; Step (2): Prepare an aqueous solution of alkali metal hydroxide with a concentration of 0.1-4 mol / L, wherein the hydroxide is one or more of sodium hydroxide and potassium hydroxide; Step (3): Add the ultrafine metal core to the zinc salt aqueous solution and heat to 60-90°C; Step (4): Add a measured amount of the hydroxide aqueous solution to make the molar ratio of hydroxide to zinc salt in the mixture 1:2-1:4; Step (5): Stir for 20-180 minutes; Step (6): After filtration and drying, zinc oxide / metal antibacterial powder is obtained.

[0018] The beneficial effects of this invention are: (1) By utilizing the semiconductor-metal interface, the antibacterial and antiviral properties of nano zinc oxide are greatly improved; (2) The production process is simple, zinc oxide is synthesized at low temperature, no calcination is required, energy consumption is low, cost is low, product dispersibility is good, and it is easy to industrialize. (3) It self-assembles into a fluffy structure on the metal surface, which has a large specific surface area and improves antibacterial and antiviral properties. Attached Figure Description

[0019] Appendix Figure 1 This is the X-ray diffraction pattern of Example 1; Appendix Figure 2 These are magnified micrographs of the powder generated in Example 1 at different magnifications; Appendix Figure 3 These are magnified micrographs of the powder generated in Example 2 at different magnifications; Appendix Figure 4 This is a magnified micrograph of the powder generated in Example 3. Detailed Implementation

[0020] The specific embodiments of the zinc oxide / metal antibacterial powder and its preparation method of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] Example 1: Prepare 100 ml of 0.1 mol / L zinc chloride aqueous solution and 100 ml of 0.4 mol / L sodium hydroxide aqueous solution. Add 7.32 g of ultrafine Zn powder to the zinc chloride solution, heat to 90 °C, add the prepared sodium hydroxide solution, stir for 20 minutes, centrifuge and filter the precipitate, and dry at 100 °C to obtain zinc oxide / zinc antibacterial powder.

[0022] The powder was formulated into a water-based coating, and its antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the HG / T 3950-2007 standard, with results showing a value greater than 99.92%. Its antiviral activity against H1N1 influenza A virus was tested using ISO 21702:2019, with a result greater than 99.92%.

[0023] Example 2: Prepare 100 ml of 2 mol / L zinc nitrate aqueous solution and 100 ml of 4 mol / L potassium hydroxide aqueous solution. Add 0.16 g of ultrafine Cu powder to the zinc chloride solution, heat to 70 °C, add the prepared potassium hydroxide solution, stir for 180 minutes, centrifuge and filter the precipitate, and dry at 100 °C to obtain zinc oxide / copper antibacterial powder.

[0024] The powder was formulated into a water-based coating, and its antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the HG / T 3950-2007 standard, with results showing a value greater than 99.95%. Its antiviral activity against H1N1 influenza A virus was tested using ISO 21702:2019, with a result greater than 99.95%.

[0025] Example 3: Prepare 100 ml of 1 mol / L zinc sulfate aqueous solution and 100 ml of 2 mol / L sodium hydroxide aqueous solution. Add 8.14 g of ultrafine Al powder to the zinc chloride solution, heat to 60°C, add the prepared sodium hydroxide solution, stir for 60 minutes, centrifuge and filter the precipitate, and dry at 100°C to obtain zinc oxide / aluminum antibacterial powder.

[0026] The powder was formulated into a water-based coating, and its antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the HG / T 3950-2007 standard, with results greater than 99.90%. Its antiviral activity against H1N1 influenza A virus was tested using ISO 21702:2019, with results greater than 99.90%.

[0027] Example 4: Prepare 100 ml of 0.1 mol / L zinc chloride aqueous solution and 200 ml of 0.1 mol / L sodium hydroxide aqueous solution. Add 1.62 g of ultrafine Zn powder to the zinc chloride solution, heat to 80 °C, add the prepared sodium hydroxide solution, stir for 20 minutes, centrifuge and filter the precipitate, and dry at 100 °C to obtain zinc oxide / zinc antibacterial powder.

[0028] The powder was formulated into a water-based coating, and its antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the HG / T 3950-2007 standard, with results showing a value greater than 99.92%. Its antiviral activity against H1N1 influenza A virus was tested using ISO 21702:2019, with a result greater than 99.92%.

[0029] Example for comparison: Prepare 100 ml of 0.1 mol / L zinc chloride aqueous solution and 100 ml of 0.4 mol / L sodium hydroxide aqueous solution. Heat to 90°C, add the prepared sodium hydroxide solution, stir for 20 minutes, centrifuge and filter the precipitate, and dry at 100°C to obtain zinc oxide powder.

[0030] The powder was formulated into a water-based coating, and its antibacterial rate against Escherichia coli and Staphylococcus aureus was tested using the HG / T 3950-2007 standard, with results showing greater than 80%. Its antiviral activity against H1N1 influenza A virus was tested using ISO 21702:2019, with results showing greater than 80%.

[0031] By comparing the four examples with the control examples, the antibacterial rate and antiviral rate of zinc oxide / metal antibacterial powder are much higher than those of zinc oxide powder alone.

[0032] In summary, the preparation method can be summarized as follows: Step (1) Prepare a zinc salt aqueous solution with a concentration of 0.1-2 mol / L, wherein the zinc salt is one or more of zinc chloride, zinc sulfate, and zinc nitrate.

[0033] Step (2) prepare an aqueous solution of an alkali metal hydroxide with a concentration of 0.1-4 mol / L, wherein the hydroxide is one or more of sodium hydroxide and potassium hydroxide. If the concentration of these two solutions is below 0.1 mol / L, the yield will be too low; if it is above 4 mol / L, the reaction will be too fast and particles will form, and a fluffy structure cannot be obtained.

[0034] Step (3): The ultrafine metal core is added to the zinc salt aqueous solution and heated to 60-90°C. Below 60°C, zinc oxide cannot be obtained, and above 90°C, the fluffy structure cannot be obtained.

[0035] Step (4): Add a measured amount of the hydroxide aqueous solution to make the molar ratio of hydroxide to zinc salt in the mixture 1:2-1:4. Zinc oxide cannot be obtained if the ratio is lower than 1:2 or higher than 1:4.

[0036] Step (5): Stir for 20-180 minutes. If the time is less than 20 minutes, the zinc oxide purity will be low and it will contain zinc hydroxide. If the time is more than 180 minutes, the yield will be reduced.

[0037] Step (6): After filtration and drying, zinc oxide / metal antibacterial powder is obtained.

[0038] The final zinc oxide / metal antibacterial powder should have a metal to zinc oxide mass ratio of 9:1 to 1:99. If the ratio is higher than 9:1, the metal content will be too high and it will easily settle. If the ratio is lower than 1:99, the metal cannot be used to form a semiconductor-metal interface.

[0039] See appendix Figure 1 , 2 The zinc oxide / zinc antibacterial powders generated in Examples 1 and 4 have a core of zinc powder particles with a diameter of 20-500 nm. The zinc oxide grown in all directions of the zinc powder particles is in the form of plates with a thickness of 10-100 nm. The sides of the plate-shaped zinc oxide are in contact with the zinc powder particles to form a semiconductor-metal interface, and the whole structure forms a fluffy ball-like structure.

[0040] See appendix Figure 3 The zinc oxide / copper antibacterial powder generated in Example 2 has a core of copper powder particles with a diameter of 20-500 nm. The zinc oxide growing in all directions of the copper powder particles is fibrous, with a diameter of 10-80 nm and a length of 200-2000 nm. The roots of the fibrous zinc oxide are connected to the copper powder particles to form a semiconductor-metal interface, and the whole structure forms a fluffy ball structure.

[0041] See appendix Figure 4 The zinc oxide / aluminum antibacterial powder generated in Example 3 has an aluminum powder core with a particle size of 20-500 nm. The zinc oxide growing in all directions of the aluminum powder particles is rod-shaped, with a diameter of 30-200 nm and a length of 100-2000 nm. One end of the rod-shaped zinc oxide is connected to the aluminum powder particle to form a semiconductor-metal interface, and the whole structure forms a fluffy ball-like structure.

[0042] Considering production and cost factors, metal powder with a particle size of 20-500nm is most suitable. If it is smaller than 20nm, the cost of metal powder is too high, and if it is larger than 500nm, the density is too high, and it is easy to settle during use.

[0043] The above are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A zinc oxide / metal antibacterial powder, characterized in that: The device includes an ultrafine metal core, in which nano-zinc oxide is grown in various directions as sheets, fibers, or rods. The ultrafine metal core is one of zinc, copper, or aluminum, with a particle size of 20-500 nm. The nano-zinc oxide has a size of 10-2000 nm. The mass ratio of the ultrafine metal core to zinc oxide is 9:1-1:

99. A semiconductor-metal interface is formed between the zinc oxide and the ultrafine metal core, and the whole device forms a fluffy structure. The zinc oxide / metal antibacterial powder is prepared by the following method: Step (1) Prepare a zinc salt aqueous solution with a concentration of 0.1-2 mol / L, wherein the zinc salt is one or more of zinc chloride, zinc sulfate, and zinc nitrate; Step (2): Prepare an aqueous solution of alkali metal hydroxide with a concentration of 0.1-4 mol / L, wherein the hydroxide is one or more of sodium hydroxide and potassium hydroxide; Step (3): Add the ultrafine metal core to the zinc salt aqueous solution and heat to 60-90°C; Step (4): Add a measured amount of the hydroxide aqueous solution to make the molar ratio of hydroxide to zinc salt in the mixture 1:2-1:4; Step (5): Stir for 20-180 minutes; Step (6): After filtration and drying, zinc oxide / metal antibacterial powder is obtained.

2. The zinc oxide / metal antibacterial powder according to claim 1, characterized in that: The nano zinc oxide is in the form of flakes, with a thickness of 10-100 nm.

3. The zinc oxide / metal antibacterial powder according to claim 1, characterized in that: The nano zinc oxide is fibrous, with a diameter of 10-80 nm and a length of 200-2000 nm.

4. The zinc oxide / metal antibacterial powder according to claim 1, characterized in that: The nano zinc oxide is rod-shaped, with a diameter of 30-200 nm and a length of 100-2000 nm.

5. The zinc oxide / metal antibacterial powder according to any one of claims 1 to 4, characterized in that: The smallest surface of the nano-zinc oxide is connected to the ultrafine metal core.

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