Nano zinc oxide and preparation method thereof
By using a continuous preparation process of circulating reactors in the preparation of nano zinc oxide, the problems of high cost and low yield in the existing technology are solved, and efficient and low-cost preparation of nano zinc oxide is achieved.
Patent Information
- Application Number
- CN202311794649.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-25
- Publication Date
- 2025-06-27
AI Technical Summary
The existing nano zinc oxide preparation methods have problems such as high cost and low yield, and it is difficult to put into use in actual production.
The continuous preparation process of nano zinc oxide is carried out by a cyclic reaction kettle. Through the cyclic reaction and separation process, the supernatant and solvent are reused, reducing production costs.
The efficient preparation of nano zinc oxide is achieved, which reduces production costs, increases yield, and improves resource utilization through solvent recovery.
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Figure CN120208281A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the technical field of zinc oxide preparation, and particularly relates to a nano zinc oxide and a preparation method thereof. Background Art
[0002] As a new type of direct bandgap wide-bandgap semiconductor material, ZnO has a bandgap width of 3.37 eV at room temperature and an exciton binding energy as high as 60 meV. Its performance is relatively stable and has biological safety, which makes it have a relatively wide application prospect in the fields of optoelectronic materials, antibacterial materials, etc. At present, the preparation methods of zinc oxide nanomaterials mainly include chemical vapor deposition method, solution method, thermal evaporation method, hydrothermal synthesis method, sol-gel method, template method, etc. However, due to the above-mentioned preparation having disadvantages such as complex process, high energy consumption, large equipment investment cost and environmental pollution, it is difficult to be further put into actual production. Summary of the Invention
[0003] This application provides a nano zinc oxide and a preparation method thereof to solve the technical problems such as high preparation cost and low yield of existing nano zinc oxide.
[0004] This application provides a preparation method of nano zinc oxide, including the following steps:
[0005] Prepare a mixed solution of surfactant and alcohol solvent;
[0006] Heat the mixed solution to a set temperature in the circulation reactor, add a precursor and a promoter for reaction; pump out the reaction solution from the bottom of the circulation reactor, and separate the reaction solution to obtain a supernatant and a solid product;
[0007] At the same time, add the supernatant, the supplemented surfactant and alcohol solvent mixed solution, the precursor, and the promoter to the top of the circulation reactor in proportion for circulation reaction;
[0008] Wash and dry the solid product to obtain nano zinc oxide.
[0009] Optionally, the precursor is any one of zinc acetate, zinc sulfate, and zinc nitrate.
[0010] Optionally, the promoter is water.
[0011] Optionally, the surfactant is any one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, and sodium oleate.
[0012] Optionally, the alcohol solvent is any one of ethanol, ethylene glycol, n-butanol, and n-hexanol.
[0013] Optionally, the molar ratio of the surfactant to the precursor is 2:1 to 1:1.
[0014] Optionally, the molar ratio of the alcohol solvent to the surfactant is 15:1 to 16:1.
[0015] Optionally, the molar ratio of the precursor to the promoter is 2:1 to 1:1;
[0016] Optionally, the reaction temperature of the circulation reactor is 80 °C to 140 °C;
[0017] Optionally, the addition ratio of the supernatant in the circulation reaction is 50% to 70%;
[0018] Optionally, the pumping rate of the reaction solution is 16 mL / min to 34 mL / min;
[0019] Optionally, the addition rate of the mixed solution of the supplementary surfactant and the solvent is 16 mL / min to 33 mL / min.
[0020] Optionally, the addition rate of the mixed solution of the supplementary precursor and the promoter is 0.2 mL / min to 0.7 mL / min.
[0021] In a second aspect, the present invention also provides a nano-zinc oxide prepared by using the preparation method described in the first aspect.
[0022] Optionally, the particle size of the nano-zinc oxide is 4 nm to 10 nm.
[0023] The above technical solution provided by the present invention has the following advantages compared with the prior art:
[0024] The present invention provides a nano-zinc oxide and a preparation method thereof. The method uses a circulation reactor to realize the continuous preparation process of nano-zinc oxide. Most of the supernatant separated by the reaction can re-participate in the continuous reaction, and part of the solution that does not participate in the cycle can be recovered by vacuum distillation; the solid obtained by distillation can effectively separate and recover the surfactant by using the difference in solvent solubility. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.
[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.
[0027] Figure 1 It is a schematic diagram of the principle of a continuous circulation preparation method of nano-zinc oxide provided in Embodiment 1 of the present application;
[0028] Figure 2 SEM image of the nano-zinc oxide provided in Embodiment 1 of the present application;
[0029] Figure 3 SEM image of the nano-zinc oxide provided in Embodiment 2 of the present application;
[0030] Figure 4 SEM image of the nano-zinc oxide provided in Embodiment 3 of the present application;
[0031] Figure 5 SEM image of the nano-zinc oxide provided in Embodiment 4 of the present application;
[0032] Figure 6 SEM image of the nano-zinc oxide provided in Embodiment 5 of the present application. Detailed implementation manners
[0033] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts shall fall within the protection scope of the present application.
[0034] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and the individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.
[0035] In this application, unless otherwise stated, terms such as "including" mean "including but not limited to". In this text, relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this text, "and / or" describes the associated relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural. In this text, "at least one" means one or more, and "multiple" means two or more. "At least one kind", "at least one of the following items" or similar expressions refer to any combination of these items, including any combination of single item or plural items. For example, "at least one of a, b, or c", or, "at least one of a, b, and c" can both mean: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.
[0036] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this application can all be obtained through market purchase or can be prepared by existing methods.
[0037] In a first aspect, this application provides a method for preparing nano - zinc oxide, comprising the following steps:
[0038] Prepare a mixed solution of surfactant and alcohol solvent;
[0039] Heat the mixed solution to a set temperature in a circulating reactor, add the precursor and promoter for reaction; pump out the reaction solution from the bottom of the circulating reactor, and separate the reaction solution to obtain a supernatant and a solid product;
[0040] At the same time, add the supernatant, supplementary surfactant, alcohol solvent mixed solution, precursor, and promoter to the top of the circulating reactor in proportion for circulating reaction;
[0041] Clean and dry the solid product to obtain nano - zinc oxide.
[0042] In an optional embodiment, the molar ratio of the surfactant to the precursor is 2:1 to 1:1.
[0043] In an optional embodiment, the cleaning and drying of the solid product specifically include: washing three times with ethanol - water and then placing it in a constant - temperature air - box for drying at room temperature.
[0044] In an alternative embodiment, the supernatant can also be separated into a solvent and a surfactant by vacuum distillation to recycle ethanol and sodium oleate.
[0045] In an alternative embodiment, the precursor is any one of zinc acetate, zinc sulfate, and zinc nitrate.
[0046] In an alternative embodiment, the promoter is water.
[0047] In an alternative embodiment, the surfactant is any one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, and sodium oleate.
[0048] In an alternative embodiment, the alcohol solvent is any one of ethanol, ethylene glycol, n-butanol, and n-hexanol.
[0049] In an alternative embodiment, the molar ratio of the alcohol solvent to the surfactant is 15:1 to 16:1.
[0050] In the above embodiment, the molar ratio of the alcohol solvent to the surfactant can be 15:1 or 16:1.
[0051] In an alternative embodiment, the molar ratio of the precursor to the promoter is 2:1 to 1:1.
[0052] In the above embodiment, the molar ratio of the precursor to the promoter can be 2:1 or 1:1.
[0053] In an alternative embodiment, the reaction temperature in the reaction kettle is 80°C to 140°C;
[0054] In the above embodiment, the reaction temperature in the reaction kettle can be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, or 140°C.
[0055] In an alternative embodiment, the addition ratio of the supernatant in the cyclic reaction is 50% to 70%;
[0056] In the above embodiment, the addition ratio of the supernatant in the cyclic reaction can be 50%, 55%, 60%, 65%, or 70%.
[0057] In an alternative embodiment, the pumping rate of the reaction solution is 16 mL / min to 34 mL / min;
[0058] In the above embodiments, the pumping rate of the solution at the bottom of the circulation reactor can be 16 mL / min, 18 mL / min, 20 mL / min, 22 mL / min, 24 mL / min, 26 mL / min, 28 mL / min, 30 mL / min, 32 mL / min or 34 mL / min.
[0059] In an alternative embodiment, the addition rate of the mixed solution of the supplementary surfactant and the solvent is 16 mL / min to 33 mL / min.
[0060] In the above embodiments, the addition rate of the mixed solution of the supplementary surfactant and the solvent can be: 16 mL / min, 18 mL / min, 20 mL / min, 22 mL / min, 24 mL / min, 26 mL / min, 28 mL / min, 30 mL / min, 32 mL / min or 33 mL / min.
[0061] In an alternative embodiment, the addition rate of the mixed solution of the supplementary precursor and the promoter is 0.2 mL / min to 0.7 mL / min.
[0062] In the above embodiments, the addition rate of the mixed solution of the supplementary precursor and the promoter can be: 0.2 mL / min, 0.3 mL / min, 0.4 mL / min, 0.5 mL / min, 0.6 mL / min or 0.7 mL / min.
[0063] In a second aspect, based on the same inventive concept, the present invention also provides a nano-zinc oxide prepared by the method for preparing nano-zinc oxide in the first aspect.
[0064] In an alternative embodiment, the particle size of the nano-zinc oxide is 4 nm to 10 nm.
[0065] During the preparation process of the present invention, due to the high surface activity of the nano-zinc oxide, a bridging effect is likely to occur at the positions without surfactant adsorption, promoting particle agglomeration. The hydrophilic groups of the anionic surfactant added in the reaction form hydrogen bond links with the hydrogen ions on the surface of the alcohol in the solvent, that is, the hydrophilic groups of the surfactant face inward and the hydrophobic groups face outward. Part of the surfactant in the solution is adsorbed on the surface of the water, providing a micro-reaction structure for the formation of nano-zinc oxide, and at the same time forming a spatial barrier for the formed nano-zinc oxide, thereby improving the dispersibility between nano-particles.
[0066] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. For the experimental methods without specific conditions indicated in the following embodiments, they are generally determined according to industry standards. If there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.
[0067] Example 1
[0068] This example provides a method for preparing nano-zinc oxide. The principle is as Figure 1 shown, and it includes the following steps:
[0069] S1. Weigh a certain mass of the surfactant sodium oleate in proportion and add it to a beaker. Measure an appropriate amount of anhydrous ethanol as a solvent and add it to the beaker to obtain a mixed solution of the surfactant and the solvent, where the molar ratio of ethanol to sodium oleate is 15.55:1.
[0070] S2. Weigh an appropriate amount of the precursor zinc acetate and add it to deionized water, and stir until it is completely dissolved to obtain a precursor solution, where the molar ratio of zinc acetate to water is 2:1.
[0071] S3. Put the above-mentioned mixed solution of the surfactant and the solvent into a circulating reaction kettle, heat it to 80 °C, add an appropriate amount of the precursor solution and a catalyst, keep it at a constant temperature and stir for 30 min;
[0072] Among them, the molar ratio of the surfactant to the precursor is 2:1.
[0073] S4. Pump out the solution from the bottom of the circulating reaction kettle at a pumping rate of 16.67 ml / min; at the same time, add a certain proportion of the supernatant, and the supplemented surfactant, solvent, precursor and promoter to the top of the circulating reaction kettle respectively, and start the circulating reaction.
[0074] Among them, the replenishment ratio of the supernatant is 50%. The remaining supernatant is recovered for ethanol and sodium oleate respectively by vacuum distillation and can be recycled. The molar ratio of the supplemented surfactant to the precursor is 2:1. The pumping rate of the supplemented sodium oleate-ethanol solution is 16.4 ml / min, and the pumping rate of the supplemented zinc acetate aqueous solution: 0.27 ml / min.
[0075] S5. After the pumped-out solution is naturally cooled to room temperature and precipitation appears, the supernatant and the solid product are separated by centrifugation; the solid product is washed three times with ethanol water and then put into a constant temperature air box and dried at room temperature to obtain white nano-zinc oxide powder.
[0076] Characterize the nano-zinc oxide to obtain the scanning electron microscope image as Figure 2 shown. It can be seen from the figure that the product is circular and the particle size range is less than 10 nm.
[0077] Example 2
[0078] This example provides a method for preparing nano-zinc oxide, including the following steps:
[0079] S1, Weigh a certain mass of the surfactant sodium dodecyl sulfate according to the proportion and add it to a beaker. Measure an appropriate amount of ethylene glycol as a solvent and add it to the beaker. Mix the surfactant and the solvent, where the molar ratio of ethylene glycol to sodium dodecyl sulfate is 15.55:1.
[0080] S2, Weigh an appropriate amount of the precursor zinc acetate and add it to deionized water, stir until it is completely dissolved, and the molar ratio of zinc acetate to water is 1:1.
[0081] S3, Put the mixed solution of the surfactant and the solvent into a reaction kettle, heat it to 120 °C, add zinc acetate and water, keep it at a constant temperature and stir for 30 min;
[0082] Among them, the molar ratio of the surfactant to the precursor is 1:1.
[0083] S4, Pump out the solution from the bottom of the circulating reaction kettle at a certain rate; at the same time, add a certain proportion of the supernatant, and the supplemented sodium dodecyl sulfate, ethylene glycol, zinc acetate and water to the top of the circulating reaction kettle respectively, and start the circulating reaction.
[0084] Among them, the addition ratio of the supernatant is 60%. The remaining supernatant can be recycled after being recovered from ethanol and sodium oleate by vacuum distillation. The pumping rate of the supplemented sodium dodecyl sulfate-ethylene glycol solution: 16.4 ml / min, and the pumping rate of the supplemented zinc acetate aqueous solution: 0.54 ml / min.
[0085] S5, After the pumped reaction solution is naturally cooled to room temperature and precipitation appears, the supernatant and the solid product are separated by centrifugation; the solid product is washed three times with ethanol water and then put into a constant temperature air oven and dried at room temperature to obtain white nano-zinc oxide powder.
[0086] Perform morphological observation on the nano-zinc oxide obtained in this example by transmission electron microscopy, as Figure 3 shown. It can be seen from the figure that the nano-zinc oxide in this example has a relatively large particle size, about 10 nm.
[0087] Example 3
[0088] This example provides a method for preparing nano-zinc oxide, including the following steps:
[0089] S1, Weigh a certain mass of the surfactant sodium dodecyl sulfonate proportionally and add it to a beaker. Measure an appropriate amount of ethylene glycol as the solvent and add it to the beaker. Mix the surfactant and the solvent. The molar ratio of sodium dodecyl sulfonate to ethylene glycol is 15:1.
[0090] S2, Weigh an appropriate amount of the precursor zinc nitrate and add it to deionized water. Stir until it is completely dissolved. The molar ratio of zinc nitrate to water is 2:1.
[0091] S3, Put the mixed solution of the surfactant and the solvent into a reaction kettle and heat it to 140 °C. Add zinc nitrate and water, keep it at a constant temperature and stir for 30 min;
[0092] Among them, the molar ratio of the surfactant to the precursor is 2:1.
[0093] S4, Pump out the solution from the bottom of the reaction kettle at a certain rate; at the same time, add a certain proportion of the supernatant, the supplemented sodium dodecyl sulfonate, ethylene glycol, zinc nitrate and water to the top of the circulating reaction kettle respectively, and start the circulating reaction.
[0094] Among them, the addition ratio of the supernatant is 60%. The remaining supernatant can be recycled after being recovered from ethanol and sodium oleate by vacuum distillation. The pumping rate of the supplemented sodium dodecyl sulfonate-ethylene glycol solution: 16.4 ml / min, the pumping rate of the supplemented zinc acetate aqueous solution: 0.27 ml / min.
[0095] S5, After the pumped reaction solution is naturally cooled to room temperature and precipitation occurs, the supernatant and the solid product are separated by centrifugation; the solid product is washed three times with ethanol water and then put into a constant temperature air box and dried at room temperature to obtain white nano zinc oxide powder.
[0096] Perform morphological observation on the nano zinc oxide obtained in this example by transmission electron microscopy, as Figure 4 shown.
[0097] Example 4
[0098] This example provides a preparation method of nano zinc oxide, including the following steps:
[0099] S1, Weigh a certain mass of the surfactant sodium dodecyl benzene sulfonate proportionally and add it to a beaker. Measure an appropriate amount of n-butanol as the solvent and add it to the beaker. Mix the surfactant and the solvent. The molar ratio of n-butanol to sodium dodecyl sulfonate is 16:1.
[0100] S2, Weigh an appropriate amount of the precursor zinc acetate and add it to deionized water. Stir until it is completely dissolved. The molar ratio of zinc acetate to water is 2:1.
[0101] S3. Put the mixed solution of surfactant and solvent into a circulating reactor, heat it to 100 °C, add zinc acetate and water, keep it at a constant temperature and stir for 30 min;
[0102] Among them, the molar ratio of the surfactant to the precursor is 2:1.
[0103] S4. Pump out the solution from the bottom of the circulating reactor at a certain rate; at the same time, add a certain proportion of the supernatant, supplemented sodium dodecylbenzenesulfonate, ethylene glycol, zinc acetate and water to the top of the reactor, and start the circulating reaction.
[0104] Among them, the addition ratio of the supernatant is 60%. The remaining supernatant can be recycled after recovering ethanol and sodium oleate by vacuum distillation. The pumping rate of the supplemented sodium dodecyl sulfate-ethylene glycol solution: 33 ml / min, and the pumping rate of the supplemented zinc acetate aqueous solution: 0.7 ml / min.
[0105] S5. After the pumped reaction solution is naturally cooled to room temperature and precipitation occurs, the supernatant and the solid product are separated by centrifugation; the solid product is washed three times with ethanol and water, then put into a constant temperature air oven and dried at room temperature to obtain white nano-zinc oxide powder.
[0106] The morphology of the nano-zinc oxide obtained in this example was observed by transmission electron microscopy, as Figure 5 shown.
[0107] Comparative Example
[0108] This comparative example provides a method for preparing nano-zinc oxide, including the following steps:
[0109] S1. Measure an appropriate amount of n-hexanol as a solvent and put it into a reactor, heat it to 100 °C.
[0110] S2. Weigh an appropriate amount of precursor zinc sulfate and add it to deionized water, stir until completely dissolved.
[0111] S3. Add the mixed solution of surfactant and solvent, add zinc acetate and water, keep it at a constant temperature and stir for 30 min; the molar ratio of zinc sulfate to water is 2:1.
[0112] S4. Pump out the solution from the bottom of the circulating reactor at a pumping rate of 16.4 ml / min; at the same time, add a certain proportion of the supernatant, supplemented n-hexanol, zinc sulfate and water to the top of the circulating reactor, and start the circulating reaction. The pumping rate of the supplemented n-hexanol solution: 16.4 ml / min; the pumping rate of the supplemented zinc sulfate aqueous solution: 0.27 ml / min.
[0113] In S5, after the pumped-out solution was naturally cooled to room temperature and precipitated, the supernatant and the solid product were separated by centrifugation. The solid product was washed three times with ethanol-water and then placed in a constant-temperature air oven and dried at room temperature to obtain white nano-zinc oxide powder.
[0114] The morphology of the nano-zinc oxide obtained in this comparative example was observed by transmission electron microscopy, as Figure 6 shown.
[0115] The obtained nano-zinc oxide product was observed for its morphology by transmission electron microscopy and the particle size was fitted. The obtained data are shown in Table 1.
[0116] Table 1 Product yields, particle sizes, and solvent recovery results of the products in Examples 1-4 and the comparative example
[0117]
[0118] As can be seen from Table 1, in the preparation methods of Examples 1-4, as the alcohol-water ratio decreased, due to the increase in water content in the reaction system, the particle size of the obtained nano-zinc oxide gradually increased. This may be because with the increase in water volume, the growth rate of nano-zinc oxide accelerated and further led to more severe agglomeration of zinc oxide. The nano-zinc oxide surface-modified with surfactants such as sodium oleate in Examples 1-4 could effectively prevent agglomeration and achieve a surface modification effect. In Comparative Example 1, without adding a surface modifier, the particle size of the prepared nano-zinc oxide increased significantly due to agglomeration, and the yield was significantly lower than that in Examples 1-4. In addition, as the carbon chain length of the alcohol solvent increased in the examples, the particle size of the prepared nano-zinc oxide also gradually decreased.
[0119] In summary, the continuous cyclic preparation method of nano-zinc oxide provided in the present invention successfully prepared nano-zinc oxide by the solution chemical method. The particle size of its product is 4 nm - 10 nm, the product yield is not less than 75%, the solvent recovery rate is not less than 95%, and the purity is greater than 97%.
[0120] The above are only specific embodiments of the present application, enabling those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel features claimed herein.
Claims
1. A preparation method of nano-zinc oxide, characterized in that, It includes the following steps: Prepare a mixed solution of surfactant and alcohol solvent; Heat the mixed solution to a set temperature in a circulating reaction kettle, add a precursor and a promoter for reaction; pump out the reaction solution from the bottom of the circulating reaction kettle, and separate the reaction solution to obtain a supernatant and a solid product; At the same time, add the supernatant, the supplemented mixed solution of surfactant and alcohol solvent, the precursor, and the promoter to the top of the circulating reaction kettle in proportion for circulating reaction; Clean and dry the solid product to obtain nano zinc oxide.
2. The preparation method according to claim 1, characterized in that, The precursor is any one of zinc acetate, zinc sulfate, and zinc nitrate.
3. The preparation method according to claim 1, characterized in that, The surfactant is any one of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, and sodium oleate; and / or The alcohol solvent is any one of ethanol, ethylene glycol, n-butanol, and n-hexanol.
4. The preparation method according to claim 1, characterized in that, The molar ratio of the alcohol solvent to the surfactant is 15:1 to 16:1; and / or The molar ratio of the precursor to the promoter is 2:1 to 1:
1.
5. The preparation method according to claim 1, characterized in that, The reaction temperature of the reaction kettle is 80°C to 140°C.
6. The preparation method according to claim 1, characterized in that, The addition ratio of the supernatant in the circulating reaction is 50% to 70%.
7. The preparation method according to claim 1, characterized in that, The pumping rate of the reaction solution: 16 mL / min to 34 mL / min.
8. The preparation method according to claim 1, characterized in that, The addition rate of the supplemented mixed solution of surfactant and solvent: 16 mL / min to 33 mL / min; and / or The addition rate of the supplemented mixed solution of precursor and promoter: 0.2 mL / min to 0.7 mL / min.
9. Nano zinc oxide prepared by the preparation method according to any one of claims 1 to 8.
10. The nano-zinc oxide according to claim 9, wherein The particle size of the nano zinc oxide is 4 nm to 10 nm.